A small nodular mass of specialized muscle fibers located in the interatrial septum near the opening of the coronary sinus. It gives rise to the atrioventricular bundle of the conduction system of the heart.
Abnormally rapid heartbeats caused by reentry of atrial impulse into the dual (fast and slow) pathways of ATRIOVENTRICULAR NODE. The common type involves a blocked atrial impulse in the slow pathway which reenters the fast pathway in a retrograde direction and simultaneously conducts to the atria and the ventricles leading to rapid HEART RATE of 150-250 beats per minute.
Small band of specialized CARDIAC MUSCLE fibers that originates in the ATRIOVENTRICULAR NODE and extends into the membranous part of the interventricular septum. The bundle of His, consisting of the left and the right bundle branches, conducts the electrical impulses to the HEART VENTRICLES in generation of MYOCARDIAL CONTRACTION.
Compounds that contain a BENZENE ring fused to a furan ring.
The small mass of modified cardiac muscle fibers located at the junction of the superior vena cava (VENA CAVA, SUPERIOR) and right atrium. Contraction impulses probably start in this node, spread over the atrium (HEART ATRIUM) and are then transmitted by the atrioventricular bundle (BUNDLE OF HIS) to the ventricle (HEART VENTRICLE).
Impaired conduction of cardiac impulse that can occur anywhere along the conduction pathway, such as between the SINOATRIAL NODE and the right atrium (SA block) or between atria and ventricles (AV block). Heart blocks can be classified by the duration, frequency, or completeness of conduction block. Reversibility depends on the degree of structural or functional defects.
Removal of tissue with electrical current delivered via electrodes positioned at the distal end of a catheter. Energy sources are commonly direct current (DC-shock) or alternating current at radiofrequencies (usually 750 kHz). The technique is used most often to ablate the AV junction and/or accessory pathways in order to interrupt AV conduction and produce AV block in the treatment of various tachyarrhythmias.
Regulation of the rate of contraction of the heart muscles by an artificial pacemaker.
Abnormally rapid heartbeats with sudden onset and cessation.
Recording of the moment-to-moment electromotive forces of the HEART as projected onto various sites on the body's surface, delineated as a scalar function of time. The recording is monitored by a tracing on slow moving chart paper or by observing it on a cardioscope, which is a CATHODE RAY TUBE DISPLAY.
They are oval or bean shaped bodies (1 - 30 mm in diameter) located along the lymphatic system.
Methods to induce and measure electrical activities at specific sites in the heart to diagnose and treat problems with the heart's electrical system.
Abnormally rapid heartbeat, usually with a HEART RATE above 100 beats per minute for adults. Tachycardia accompanied by disturbance in the cardiac depolarization (cardiac arrhythmia) is called tachyarrhythmia.
A form of ventricular pre-excitation characterized by a short PR interval and a long QRS interval with a delta wave. In this syndrome, atrial impulses are abnormally conducted to the HEART VENTRICLES via an ACCESSORY CONDUCTING PATHWAY that is located between the wall of the right or left atria and the ventricles, also known as a BUNDLE OF KENT. The inherited form can be caused by mutation of PRKAG2 gene encoding a gamma-2 regulatory subunit of AMP-activated protein kinase.
A generic expression for any tachycardia that originates above the BUNDLE OF HIS.
The chambers of the heart, to which the BLOOD returns from the circulation.
A rare form of supraventricular tachycardia caused by automatic, not reentrant, conduction initiated from sites at the atrioventricular junction, but not the ATRIOVENTRICULAR NODE. It usually occurs during myocardial infarction, after heart surgery, or in digitalis intoxication with a HEART RATE ranging from 140 to 250 beats per minute.
Abnormal cardiac rhythm that is characterized by rapid, uncoordinated firing of electrical impulses in the upper chambers of the heart (HEART ATRIA). In such case, blood cannot be effectively pumped into the lower chambers of the heart (HEART VENTRICLES). It is caused by abnormal impulse generation.
The hemodynamic and electrophysiological action of the HEART ATRIA.
Procedures using an electrically heated wire or scalpel to treat hemorrhage (e.g., bleeding ulcers) and to ablate tumors, mucosal lesions, and refractory arrhythmias. It is different from ELECTROSURGERY which is used more for cutting tissue than destroying and in which the patient is part of the electric circuit.
A condition caused by dysfunctions related to the SINOATRIAL NODE including impulse generation (CARDIAC SINUS ARREST) and impulse conduction (SINOATRIAL EXIT BLOCK). It is characterized by persistent BRADYCARDIA, chronic ATRIAL FIBRILLATION, and failure to resume sinus rhythm following CARDIOVERSION. This syndrome can be congenital or acquired, particularly after surgical correction for heart defects.
Rapid, irregular atrial contractions caused by a block of electrical impulse conduction in the right atrium and a reentrant wave front traveling up the inter-atrial septum and down the right atrial free wall or vice versa. Unlike ATRIAL FIBRILLATION which is caused by abnormal impulse generation, typical atrial flutter is caused by abnormal impulse conduction. As in atrial fibrillation, patients with atrial flutter cannot effectively pump blood into the lower chambers of the heart (HEART VENTRICLES).
The period of time following the triggering of an ACTION POTENTIAL when the CELL MEMBRANE has changed to an unexcitable state and is gradually restored to the resting (excitable) state. During the absolute refractory period no other stimulus can trigger a response. This is followed by the relative refractory period during which the cell gradually becomes more excitable and the stronger impulse that is required to illicit a response gradually lessens to that required during the resting state.
A diverticulum from the fourth pharyngeal pouch of an embryo, regarded by some as a rudimentary fifth pharyngeal pouch and by others as a lateral thyroid primordium. The ultimobranchial bodies of lower vertebrates contain large amounts of calcitonin. In mammals the bodies fuse with the thyroid gland and are thought to develop into the parafollicular cells. (Stedman, 25th ed)
An enzyme substrate which permits the measurement of peptide hydrolase activity, e.g. trypsin and thrombin. The enzymes liberate 2-naphthylamine, which is measured by colorimetric procedures.
Abnormally rapid heartbeats originating from one or more automatic foci (nonsinus pacemakers) in the HEART ATRIUM but away from the SINOATRIAL NODE. Unlike the reentry mechanism, automatic tachycardia speeds up and slows down gradually. The episode is characterized by a HEART RATE between 135 to less than 200 beats per minute and lasting 30 seconds or longer.
Stable blood coagulation factor involved in the intrinsic pathway. The activated form XIa activates factor IX to IXa. Deficiency of factor XI is often called hemophilia C.
The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.
A device designed to stimulate, by electric impulses, contraction of the heart muscles. It may be temporary (external) or permanent (internal or internal-external).
The 10th cranial nerve. The vagus is a mixed nerve which contains somatic afferents (from skin in back of the ear and the external auditory meatus), visceral afferents (from the pharynx, larynx, thorax, and abdomen), parasympathetic efferents (to the thorax and abdomen), and efferents to striated muscle (of the larynx and pharynx).
Electromagnetic waves with frequencies between about 3 kilohertz (very low frequency - VLF) and 300,000 megahertz (extremely high frequency - EHF). They are used in television and radio broadcasting, land and satellite communications systems, radionavigation, radiolocation, and DIATHERMY. The highest frequency radio waves are MICROWAVES.
Impaired impulse conduction from HEART ATRIA to HEART VENTRICLES. AV block can mean delayed or completely blocked impulse conduction.
Agents used for the treatment or prevention of cardiac arrhythmias. They may affect the polarization-repolarization phase of the action potential, its excitability or refractoriness, or impulse conduction or membrane responsiveness within cardiac fibers. Anti-arrhythmia agents are often classed into four main groups according to their mechanism of action: sodium channel blockade, beta-adrenergic blockade, repolarization prolongation, or calcium channel blockade.
Modified cardiac muscle fibers composing the terminal portion of the heart conduction system.
The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)
Any disturbances of the normal rhythmic beating of the heart or MYOCARDIAL CONTRACTION. Cardiac arrhythmias can be classified by the abnormalities in HEART RATE, disorders of electrical impulse generation, or impulse conduction.
The lower right and left chambers of the heart. The right ventricle pumps venous BLOOD into the LUNGS and the left ventricle pumps oxygenated blood into the systemic arterial circulation.
Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.
The number of times the HEART VENTRICLES contract per unit of time, usually per minute.
A group of homologous proteins which form the intermembrane channels of GAP JUNCTIONS. The connexins are the products of an identified gene family which has both highly conserved and highly divergent regions. The variety contributes to the wide range of functional properties of gap junctions.
Recording of regional electrophysiological information by analysis of surface potentials to give a complete picture of the effects of the currents from the heart on the body surface. It has been applied to the diagnosis of old inferior myocardial infarction, localization of the bypass pathway in Wolff-Parkinson-White syndrome, recognition of ventricular hypertrophy, estimation of the size of a myocardial infarct, and the effects of different interventions designed to reduce infarct size. The limiting factor at present is the complexity of the recording and analysis, which requires 100 or more electrodes, sophisticated instrumentation, and dedicated personnel. (Braunwald, Heart Disease, 4th ed)
Surgical excision of one or more lymph nodes. Its most common use is in cancer surgery. (From Dorland, 28th ed, p966)
Studies in which individuals or populations are followed to assess the outcome of exposures, procedures, or effects of a characteristic, e.g., occurrence of disease.
Tumors in any part of the heart. They include primary cardiac tumors and metastatic tumors to the heart. Their interference with normal cardiac functions can cause a wide variety of symptoms including HEART FAILURE; CARDIAC ARRHYTHMIAS; or EMBOLISM.
Electrodes with an extremely small tip, used in a voltage clamp or other apparatus to stimulate or record bioelectric potentials of single cells intracellularly or extracellularly. (Dorland, 28th ed)
Theoretical representations that simulate the behavior or activity of the cardiovascular system, processes, or phenomena; includes the use of mathematical equations, computers and other electronic equipment.
The valve consisting of three cusps situated between the right atrium and right ventricle of the heart.
The hollow, muscular organ that maintains the circulation of the blood.
A diagnostic procedure used to determine whether LYMPHATIC METASTASIS has occurred. The sentinel lymph node is the first lymph node to receive drainage from a neoplasm.
The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.
Elements of limited time intervals, contributing to particular results or situations.
A nucleoside that is composed of ADENINE and D-RIBOSE. Adenosine or adenosine derivatives play many important biological roles in addition to being components of DNA and RNA. Adenosine itself is a neurotransmitter.

A comparison of an A1 adenosine receptor agonist (CVT-510) with diltiazem for slowing of AV nodal conduction in guinea-pig. (1/783)

1. The purpose of this study was to compare the pharmacological properties (i.e. the AV nodal depressant, vasodilator, and inotropic effects) of two AV nodal blocking agents belonging to different drug classes; a novel A1 adenosine receptor (A1 receptor) agonist, N-(3(R)-tetrahydrofuranyl)-6-aminopurine riboside (CVT-510), and the prototypical calcium channel blocker diltiazem. 2. In the atrial-paced isolated heart, CVT-510 was approximately 5 fold more potent to prolong the stimulus-to-His bundle (S-H interval), a measure of slowing AV nodal conduction (EC50 = 41 nM) than to increase coronary conductance (EC50 = 200 nM). At concentrations of CVT-510 (40 nM) and diltiazem (1 microM) that caused equal prolongation of S-H interval (approximately 10 ms), diltiazem, but not CVT-510, significantly reduced left ventricular developed pressure (LVP) and markedly increased coronary conductance. CVT-510 shortened atrial (EC50 = 73 nM) but not the ventricular monophasic action potentials (MAP). 3. In atrial-paced anaesthetized guinea-pigs, intravenous infusions of CVT-510 and diltiazem caused nearly equal prolongations of P-R interval. However, diltiazem, but not CVT-510, significantly reduced mean arterial blood pressure. 4. Both CVT-510 and diltiazem prolonged S-H interval, i.e., slowed AV nodal conduction. However, the A1 receptor-selective agonist CVT-510 did so without causing the negative inotropic, vasodilator, and hypotensive effects associated with diltiazem. Because CVT-510 did not affect the ventricular action potential, it is unlikely that this agonist will have a proarrythmic action in ventricular myocardium.  (+info)

Modulation of AV nodal and Hisian conduction by changes in extracellular space. (2/783)

Previous studies have demonstrated that the extracellular space (ECS) component of the atrioventricular (AV) node and His bundle region is larger than the ECS in adjacent contractile myocardium. The potential physiological significance of this observation was examined in a canine blood-perfused AV nodal preparation. Mannitol, an ECS osmotic expander, was infused directly into either the AV node or His bundle region. This resulted in a significant dose-dependent increase in the AV nodal or His-ventricular conduction time and in the AV nodal effective refractory period. Mannitol infusion eventually resulted in Wenckebach block (n = 6), which reversed with mannitol washout. The ratio of AV nodal to left ventricular ECS in tissue frozen immediately on the development of heart block (n = 8) was significantly higher in the region of block (4.53 +/- 0.61) compared with that in control preparations (2.23 +/- 0.35, n = 6, P < 0.01) and donor dog hearts (2.45 +/- 0.18, n = 11, P < 0.01) not exposed to mannitol. With lower mannitol rates (10% of total blood flow), AV nodal conduction times increased by 5-10% and the AV node became supersensitive to adenosine, acetylcholine, and carbachol, but not to norepinephrine. We conclude that mannitol-induced changes in AV node and His bundle ECS markedly alter conduction system electrophysiology and the sensitivity of conductive tissues to purinergic and cholinergic agonists.  (+info)

Ventricular excitation maps using tissue Doppler acceleration imaging: potential clinical application. (3/783)

OBJECTIVES: The purpose of this study is to validate the use of tissue Doppler acceleration imaging (TDAI) for evaluation of the onset of ventricular contraction in humans. BACKGROUND: Tissue Doppler acceleration imaging can display the distribution, direction and value of ventricular acceleration responses to myocardial contraction and electrical excitation. METHODS: Twenty normal volunteers underwent TDAI testing to determine the normal onset of ventricular acceleration. Two patients with paroxysmal supraventricular tachycardia and 30 patients with permanent pacemakers underwent introduction of esophageal and right ventricular pacing electrodes, respectively, and were studied to visualize the onset of pacer-induced ventricular acceleration. Eight patients with dual atrioventricular (AV) node and 20 patients with Wolff-Parkinson-White (WPW) syndrome underwent TDAI testing to localize the abnormal onset of ventricular acceleration, and the results were compared with those of intracardiac electrophysiology (ICEP) tests. RESULTS: The normal onset and the onset of dual AV node were localized at the upper interventricular septum (IVS) under the right coronary cusp within 25 ms before the beginning of the R wave in the electrocardiogram (ECG). In all patients in the pacing group, the location and timing of the onset conformed to the positions and timing of electrodes (100%). In patients with WPW syndrome, abnormal onset was localized to portions of the ventricular wall other than the upper IVS at the delta wave or within 25 ms after the delta wave in the ECG. The agreement was 90% (18 of 20) between the abnormal onset and the position of the accessory pathways determined by ICEP testing. CONCLUSIONS: These results suggest that TDAI is a useful noninvasive method that frequently is successful in visualizing the intramural site of origin of ventricular mechanical contraction.  (+info)

Anatomical study of truncus arteriousus communis with embryological and surgical considerations. (4/783)

Twelve specimens of truncus arteriosus communis have been studied anatomically, with special reference to the conal anatomy and to the associated cardiac anomalies which can create additional problems if surgical repair is planned. A wide spectrum of conal morphology has been observed, suggesting that differential conal absorption is a developmental characteristic of truncus arteriousus as well as of transposition complexes. The invariable absence of septation of the ventricular infundibula and semilunar valves, in spite of the variable anatomy of the free wall of the conus, indicates that all types of truncus arteriosus, ontogenetically, should be considered as a single undivided conotruncus. Various types of ventircular septal defect were found: (a) ventricular septal defect with absent crista, in which no remnants of conal septum are present; (b) supracristal ventricular septal defect, in which vestigial conal septum is seen in front of the membranous septum; (c) bulloventricular foramen, associated with univentricular origin of the truncus from the right ventricle. Frequent associated anomalies are underdevelopment of the aortic arch, truncal valve malformations, and obstructive ventricular septal defect. The AV conduction system studied in one case showed an arrangement similar to Fallot's tetralogy with the His bundle and the left bundle-branch in a safe position behind the posteroinferior rim of the defect. The postoperative fate of the frequently abnormal truncal valve and the theoretical indications for total repair for Type IV truncus are also discussed.  (+info)

Electrophysiological effects of mexiletine in man. (5/783)

The electrophysiological effects of intravenous mexiletine in a dose of 200 to 250 mg given over 5 minutes, followed by continuous infusion of 60 to 90 mg per hour, were studied in 5 patients with normal conduction and in 20 patients with a variety of disturbances of impulse formation and conduction, by means of His bundle electrography, atrial pacing, and the extrastimulus method. In all but 2 patients the plasma level was above the lower therapeutic limit. Mexiletine had no consistent effects on sinus frequency and atrial refractoriness. The sinoatrial recovery time changed inconsistently in both directions; however, of the 5 patients in whom an increase was evident, 3 had sinus node dysfunction. In most patients mexiletine increased the AV nodal conduction time at paced atrial rates and shifted the Wenckebach point to a lower atrial rate. The effective refractory period of the AV node was not consistently influenced, while the functional refractory period increased in 12 out of 14 patients. The HV intervals increased by a mean of 11 ms in 8 patients and were unchanged in 17. Both the relative and effective refractory period of the His-Purkinje system increased after mexiletine. Non-cardiac side effects occurred in 7 out of 25 patients, and cardiac side effects, including one serious, in 2. The results indicate that mexiletine shares some electrophysiological properties with procainamide and quinidine, when given to patients with conduction defects, and that the drug should not be used in patients with pre-existing impairment of impulse formation or conduction. It has additional effects on AV nodal conduction which may be of value in the treatment of re-entrant tachycardias involving the AV node.  (+info)

Monophasic action potentials of right atrium and electrophysiological properties of AV conducting system in patients with hypothyroidism. (6/783)

In 12 patients with manifest hypothyroidism right atrial monophasic action potentials showed a significant prolongation in comparison with data from normal or euthyroid patients. Atrial effective refractory periods were also significantly prolonged. After thyroid treatment the monophasic action potential duration and the effective refractory period of the right atrium were within normal ranges. In 6 hypothyroid patients studies of AV conduction with the aid of His bundle electrography and atrial pacing showed a supraHisian conduction delay which was manifest in one case and latent in another two. InfraHisian conduction delay was encountered in 2 cases.  (+info)

The nerve supply and conducting system of the human heart at the end of the embryonic period proper. (7/783)

The nerve supply and conducting system were studied in a stage 23 human embryo of exceptional histological quality. The nerves on the right side arose from cervical sympathetic and from cervical and thoracic vagal filaments. Out of their interconnexions vagoxympathetic nerves emerged, which (1) sent a branch in front of the trachea to the aorticopulmonary ganglion, thereby supplying arterial and venous structures, and (2) formed the right sinal nerve, which supplied the sinu-atrial node, and gave filaments to the interatrial septum which could be traced to the atrioventricular node and pulmonary veins. The nerves on the left side arose similarly from cervical sympathetic and from cervical and thoracic vagal filaments. These formed several descending, ganglionated, vagosympathetic filaments that descended to the right of the arch of the aorta and entered the aorticopulmonary ganglion. Filaments leaving the ganglion supplied the pulmonary trunk, ascending aorta, interatrial septum, pulmonary veins, and, as the left sinal nerve, the fold of the left vena cava. The thoracic vagal filaments descended to the left of the arch of the aorta and supplied chiefly the arterial end of the heart. No thoracic sympathetic cardiac filaments were found. The sinu-atrial node began as a crescentic mass in front of the lower part of the superior vena cava. It gradually extended on each side of the superior vena cava and came to form its posterior wall at a more caudal level. The atrial myocardium that formed the septum spurium, venous valves, and interatrial septum could be traced from the sinu-atrial to the atrioventricular node. Myocardium also encircled the atrial aspects of the atrioventricular orifices, and could be traced caudally to the atrioventricular nde. The atrioventricular node was a conspicuous mass in the anterior and lower part of the interatrial septum, from which a clearly defined bundle left to enter the interventricular septum. Right and left limbs were observed, the former being a rounded bundle that passed immediately in front of the root of the aorta.  (+info)

Atrioventricular nodal conduction during atrial fibrillation: role of atrial input modification. (8/783)

BACKGROUND: Posteroseptal ablation of the atrioventricular node (AVN) has been proposed as a means to slow the ventricular rate during atrial fibrillation (AF). The suggested mechanism is elimination of the AVN "slow pathway." On the basis of the unpredictable success of the procedure, we hypothesize that, in fact, the slow pathway is preserved. Therefore, the slowing of the ventricular rate results from reduced bombardment of the AVN. METHODS AND RESULTS: In 8 rabbit heart atrial-AVN preparations, cooling of the posterior and/or the anterior AVN approaches revealed nonspecific effects on the slow and fast pathway portions of the AVN conduction curve. In 13 other preparations, simulated AF during posterior cooling (n=6) prolonged the His-His (H-H) intervals but did not reveal specific slow pathway injury. In the remaining 7 preparations, AF was applied before and after posteroseptal surgical cuts. During AF with posterior origin, the cuts resulted in longer mean H-H along with slowing of the AVN bombardment rate. However, there was no change in the minimum observed H-H, suggesting an intact slow pathway. During AF with anterior origin, the mean and the shortest H-H remained unchanged before and after the cuts in all preparations. This was associated with the maintenance of high-rate AVN bombardment. CONCLUSIONS: Posteroseptal ablation does not eliminate the slow pathway. Ventricular rate slowing can be obtained if the ablation procedure results in a posteroanterior intra-atrial block leading to a reduction of the rate of AV nodal bombardment.  (+info)

The atrioventricular (AV) node is a critical part of the electrical conduction system of the heart. It is a small cluster of specialized cardiac muscle cells located in the lower interatrial septum, near the opening of the coronary sinus. The AV node receives electrical impulses from the sinoatrial node (the heart's natural pacemaker) via the internodal pathways and delays their transmission for a brief period before transmitting them to the bundle of His and then to the ventricles. This delay allows the atria to contract and empty their contents into the ventricles before the ventricles themselves contract, ensuring efficient pumping of blood throughout the body.

The AV node plays an essential role in maintaining a normal heart rhythm, as it can also function as a backup pacemaker if the sinoatrial node fails to generate impulses. However, certain heart conditions or medications can affect the AV node's function and lead to abnormal heart rhythms, such as atrioventricular block or atrial tachycardia.

Atrioventricular (AV) nodal reentrant tachycardia (AVNRT) is a type of supraventricular tachycardia (SVT), which is a rapid heart rhythm originating at or above the atrioventricular node. In AVNRT, an abnormal electrical circuit in or near the AV node creates a reentry pathway that allows for rapid heart rates, typically greater than 150-250 beats per minute.

In normal conduction, the electrical impulse travels from the atria to the ventricles through the AV node and then continues down the bundle branches to the Purkinje fibers, resulting in a coordinated contraction of the heart. In AVNRT, an extra electrical pathway exists that allows for the reentry of the electrical impulse back into the atria, creating a rapid and abnormal circuit.

AVNRT is classified based on the direction of the reentry circuit:

1. Typical or common AVNRT: The most common form, accounting for 90% of cases. In this type, the reentry circuit involves an "anterior" and a "posterior" loop in or near the AV node. The anterior loop has slower conduction velocity than the posterior loop, creating a "short" reentry circuit that is responsible for the rapid heart rate.
2. Atypical AVNRT: Less common, accounting for 10% of cases. In this type, the reentry circuit involves an "outer" and an "inner" loop around the AV node. The outer loop has slower conduction velocity than the inner loop, creating a "long" reentry circuit that is responsible for the rapid heart rate.

AVNRT can present with symptoms such as palpitations, dizziness, lightheadedness, shortness of breath, chest discomfort, or syncope (fainting). Treatment options include observation, vagal maneuvers, medications, and catheter ablation. Catheter ablation is a curative treatment that involves the destruction of the abnormal electrical pathway using radiofrequency energy or cryotherapy.

The Bundle of His is a bundle of specialized cardiac muscle fibers that conduct electrical impulses to the Purkinje fibers, which then stimulate contraction of the ventricles in the heart. It is named after Wilhelm His, Jr., who first described it in 1893.

The Bundle of His is a part of the electrical conduction system of the heart that helps coordinate the contraction of the atria and ventricles to ensure efficient pumping of blood. The bundle originates from the atrioventricular node, which receives electrical impulses from the sinoatrial node (the heart's natural pacemaker) and transmits them through the Bundle of His to the Purkinje fibers.

The Bundle of His is divided into two main branches, known as the right and left bundle branches, which further divide into smaller fascicles that spread throughout the ventricular myocardium. This ensures a coordinated contraction of the ventricles, allowing for efficient pumping of blood to the rest of the body.

Benzofurans are a class of organic compounds that consist of a benzene ring fused to a furan ring. The furan ring is a five-membered aromatic heterocycle containing one oxygen atom and four carbon atoms. Benzofurans can be found in various natural and synthetic substances. Some benzofuran derivatives have biological activity and are used in medicinal chemistry, while others are used as flavorings or fragrances. However, some benzofuran compounds are also known to have psychoactive effects and can be abused as recreational drugs.

The sinoatrial (SA) node, also known as the sinus node, is the primary pacemaker of the heart. It is a small bundle of specialized cardiac conduction tissue located in the upper part of the right atrium, near the entrance of the superior vena cava. The SA node generates electrical impulses that initiate each heartbeat, causing the atria to contract and pump blood into the ventricles. This process is called sinus rhythm.

The SA node's electrical activity is regulated by the autonomic nervous system, which can adjust the heart rate in response to changes in the body's needs, such as during exercise or rest. The SA node's rate of firing determines the heart rate, with a normal resting heart rate ranging from 60 to 100 beats per minute.

If the SA node fails to function properly or its electrical impulses are blocked, other secondary pacemakers in the heart may take over, resulting in abnormal heart rhythms called arrhythmias.

Heart block is a cardiac condition characterized by the interruption of electrical impulse transmission from the atria (the upper chambers of the heart) to the ventricles (the lower chambers of the heart). This disruption can lead to abnormal heart rhythms, including bradycardia (a slower-than-normal heart rate), and in severe cases, can cause the heart to stop beating altogether. Heart block is typically caused by damage to the heart's electrical conduction system due to various factors such as aging, heart disease, or certain medications.

There are three types of heart block: first-degree, second-degree, and third-degree (also known as complete heart block). Each type has distinct electrocardiogram (ECG) findings and symptoms. Treatment for heart block depends on the severity of the condition and may include monitoring, medication, or implantation of a pacemaker to regulate the heart's electrical activity.

Catheter ablation is a medical procedure in which specific areas of heart tissue that are causing arrhythmias (irregular heartbeats) are destroyed or ablated using heat energy (radiofrequency ablation), cold energy (cryoablation), or other methods. The procedure involves threading one or more catheters through the blood vessels to the heart, where the tip of the catheter can be used to selectively destroy the problematic tissue. Catheter ablation is often used to treat atrial fibrillation, atrial flutter, and other types of arrhythmias that originate in the heart's upper chambers (atria). It may also be used to treat certain types of arrhythmias that originate in the heart's lower chambers (ventricles), such as ventricular tachycardia.

The goal of catheter ablation is to eliminate or reduce the frequency and severity of arrhythmias, thereby improving symptoms and quality of life. In some cases, it may also help to reduce the risk of stroke and other complications associated with arrhythmias. Catheter ablation is typically performed by a specialist in heart rhythm disorders (electrophysiologist) in a hospital or outpatient setting under local anesthesia and sedation. The procedure can take several hours to complete, depending on the complexity of the arrhythmia being treated.

It's important to note that while catheter ablation is generally safe and effective, it does carry some risks, such as bleeding, infection, damage to nearby structures, and the possibility of recurrent arrhythmias. Patients should discuss the potential benefits and risks of the procedure with their healthcare provider before making a decision about treatment.

Artificial cardiac pacing is a medical procedure that involves the use of an artificial device to regulate and stimulate the contraction of the heart muscle. This is often necessary when the heart's natural pacemaker, the sinoatrial node, is not functioning properly and the heart is beating too slowly or irregularly.

The artificial pacemaker consists of a small generator that produces electrical impulses and leads that are positioned in the heart to transmit the impulses. The generator is typically implanted just under the skin in the chest, while the leads are inserted into the heart through a vein.

There are different types of artificial cardiac pacing systems, including single-chamber pacemakers, which stimulate either the right atrium or right ventricle, and dual-chamber pacemakers, which stimulate both chambers of the heart. Some pacemakers also have additional features that allow them to respond to changes in the body's needs, such as during exercise or sleep.

Artificial cardiac pacing is a safe and effective treatment for many people with abnormal heart rhythms, and it can significantly improve their quality of life and longevity.

Paroxysmal Tachycardia is a type of arrhythmia (abnormal heart rhythm) characterized by rapid and abrupt onset and offset of episodes of tachycardia, which are faster than normal heart rates. The term "paroxysmal" refers to the sudden and recurring nature of these episodes.

Paroxysmal Tachycardia can occur in various parts of the heart, including the atria (small upper chambers) or ventricles (larger lower chambers). The two most common types are Atrial Paroxysmal Tachycardia (APT) and Ventricular Paroxysmal Tachycardia (VPT).

APT is more common and typically results in a rapid heart rate of 100-250 beats per minute. It usually begins and ends suddenly, lasting for seconds to hours. APT can cause symptoms such as palpitations, lightheadedness, shortness of breath, chest discomfort, or anxiety.

VPT is less common but more serious because it involves the ventricles, which are responsible for pumping blood to the rest of the body. VPT can lead to decreased cardiac output and potentially life-threatening conditions such as syncope (fainting) or even cardiac arrest.

Treatment options for Paroxysmal Tachycardia depend on the underlying cause, severity, and frequency of symptoms. These may include lifestyle modifications, medications, cardioversion (electrical shock to restore normal rhythm), catheter ablation (destroying problematic heart tissue), or implantable devices such as pacemakers or defibrillators.

Electrocardiography (ECG or EKG) is a medical procedure that records the electrical activity of the heart. It provides a graphic representation of the electrical changes that occur during each heartbeat. The resulting tracing, called an electrocardiogram, can reveal information about the heart's rate and rhythm, as well as any damage to its cells or abnormalities in its conduction system.

During an ECG, small electrodes are placed on the skin of the chest, arms, and legs. These electrodes detect the electrical signals produced by the heart and transmit them to a machine that amplifies and records them. The procedure is non-invasive, painless, and quick, usually taking only a few minutes.

ECGs are commonly used to diagnose and monitor various heart conditions, including arrhythmias, coronary artery disease, heart attacks, and electrolyte imbalances. They can also be used to evaluate the effectiveness of certain medications or treatments.

Lymph nodes are small, bean-shaped organs that are part of the immune system. They are found throughout the body, especially in the neck, armpits, groin, and abdomen. Lymph nodes filter lymph fluid, which carries waste and unwanted substances such as bacteria, viruses, and cancer cells. They contain white blood cells called lymphocytes that help fight infections and diseases by attacking and destroying the harmful substances found in the lymph fluid. When an infection or disease is present, lymph nodes may swell due to the increased number of immune cells and fluid accumulation as they work to fight off the invaders.

Electrophysiologic techniques, cardiac, refer to medical procedures used to study the electrical activities and conduction systems of the heart. These techniques involve the insertion of electrode catheters into the heart through blood vessels under fluoroscopic guidance to record and stimulate electrical signals. The information obtained from these studies can help diagnose and evaluate various cardiac arrhythmias, determine the optimal treatment strategy, and assess the effectiveness of therapies such as ablation or implantable devices.

The electrophysiologic study (EPS) is a type of cardiac electrophysiologic technique that involves the measurement of electrical signals from different regions of the heart to evaluate its conduction system's function. The procedure can help identify the location of abnormal electrical pathways responsible for arrhythmias and determine the optimal treatment strategy, such as catheter ablation or medication therapy.

Cardiac electrophysiologic techniques are also used in device implantation procedures, such as pacemaker or defibrillator implantation, to ensure proper placement and function of the devices. These techniques can help program and test the devices to optimize their settings for each patient's needs.

In summary, cardiac electrophysiologic techniques are medical procedures used to study and manipulate the electrical activities of the heart, helping diagnose and treat various arrhythmias and other cardiac conditions.

Tachycardia is a medical term that refers to an abnormally rapid heart rate, often defined as a heart rate greater than 100 beats per minute in adults. It can occur in either the atria (upper chambers) or ventricles (lower chambers) of the heart. Different types of tachycardia include supraventricular tachycardia (SVT), atrial fibrillation, atrial flutter, and ventricular tachycardia.

Tachycardia can cause various symptoms such as palpitations, shortness of breath, dizziness, lightheadedness, chest discomfort, or syncope (fainting). In some cases, tachycardia may not cause any symptoms and may only be detected during a routine physical examination or medical test.

The underlying causes of tachycardia can vary widely, including heart disease, electrolyte imbalances, medications, illicit drug use, alcohol abuse, smoking, stress, anxiety, and other medical conditions. In some cases, the cause may be unknown. Treatment for tachycardia depends on the underlying cause, type, severity, and duration of the arrhythmia.

Wolff-Parkinson-White (WPW) Syndrome is a heart condition characterized by the presence of an accessory pathway or abnormal electrical connection between the atria (the upper chambers of the heart) and ventricles (the lower chambers of the heart). This accessory pathway allows electrical impulses to bypass the normal conduction system, leading to a shorter PR interval and a "delta wave" on the electrocardiogram (ECG), which is the hallmark of WPW Syndrome.

Individuals with WPW Syndrome may experience no symptoms or may have palpitations, rapid heartbeat (tachycardia), or episodes of atrial fibrillation. In some cases, WPW Syndrome can lead to more serious heart rhythm disturbances and may require treatment, such as medication, catheter ablation, or in rare cases, surgery.

It is important to note that not all individuals with WPW Syndrome will experience symptoms or complications, and many people with this condition can lead normal, active lives with appropriate monitoring and management.

Supraventricular tachycardia (SVT) is a rapid heart rhythm that originates above the ventricles (the lower chambers of the heart). This type of tachycardia includes atrial tachycardia, atrioventricular nodal reentrant tachycardia (AVNRT), and atrioventricular reentrant tachycardia (AVRT). SVT usually causes a rapid heartbeat that starts and stops suddenly, and may not cause any other symptoms. However, some people may experience palpitations, shortness of breath, chest discomfort, dizziness, or fainting. SVT is typically diagnosed through an electrocardiogram (ECG) or Holter monitor, and can be treated with medications, cardioversion, or catheter ablation.

The heart atria are the upper chambers of the heart that receive blood from the veins and deliver it to the lower chambers, or ventricles. There are two atria in the heart: the right atrium receives oxygen-poor blood from the body and pumps it into the right ventricle, which then sends it to the lungs to be oxygenated; and the left atrium receives oxygen-rich blood from the lungs and pumps it into the left ventricle, which then sends it out to the rest of the body. The atria contract before the ventricles during each heartbeat, helping to fill the ventricles with blood and prepare them for contraction.

Tachycardia refers to a rapid heart rate, typically defined as over 100 beats per minute in adults. Ectopic junctional tachycardia (EJT) is a specific type of abnormal heart rhythm that originates from the junction between the atria (the upper chambers of the heart) and ventricles (the lower chambers).

In EJT, the electrical impulse arises from an ectopic focus (an area outside of the normal conduction system) located in or near the atrioventricular (AV) node. This results in a rapid heart rate that can range from 100 to 250 beats per minute.

EJT is often seen in patients after cardiac surgery, and it can also occur in other conditions such as myocarditis, digoxin toxicity, or following congenital heart disease repair. It may cause symptoms such as palpitations, shortness of breath, chest discomfort, or dizziness. Treatment options for EJT include medications, cardioversion, or ablation therapy, depending on the underlying cause and severity of symptoms.

Atrial fibrillation (A-tre-al fi-bru-la'shun) is a type of abnormal heart rhythm characterized by rapid and irregular beating of the atria, the upper chambers of the heart. In this condition, the electrical signals that coordinate heartbeats don't function properly, causing the atria to quiver instead of contracting effectively. As a result, blood may not be pumped efficiently into the ventricles, which can lead to blood clots, stroke, and other complications. Atrial fibrillation is a common type of arrhythmia and can cause symptoms such as palpitations, shortness of breath, fatigue, and dizziness. It can be caused by various factors, including heart disease, high blood pressure, age, and genetics. Treatment options include medications, electrical cardioversion, and surgical procedures to restore normal heart rhythm.

Atrial function in a medical context refers to the role and performance of the two upper chambers of the heart, known as the atria. The main functions of the atria are to receive blood from the veins and help pump it into the ventricles, which are the lower pumping chambers of the heart.

The atria contract in response to electrical signals generated by the sinoatrial node, which is the heart's natural pacemaker. This contraction helps to fill the ventricles with blood before they contract and pump blood out to the rest of the body. Atrial function can be assessed through various diagnostic tests, such as echocardiograms or electrocardiograms (ECGs), which can help identify any abnormalities in atrial structure or electrical activity that may affect heart function.

Electrocoagulation is a medical procedure that uses heat generated from an electrical current to cause coagulation (clotting) of tissue. This procedure is often used to treat a variety of medical conditions, such as:

* Gastrointestinal bleeding: Electrocoagulation can be used to control bleeding in the stomach or intestines by applying an electrical current to the affected blood vessels, causing them to shrink and clot.
* Skin lesions: Electrocoagulation can be used to remove benign or malignant skin lesions, such as warts, moles, or skin tags, by applying an electrical current to the growth, which causes it to dehydrate and eventually fall off.
* Vascular malformations: Electrocoagulation can be used to treat vascular malformations (abnormal blood vessels) by applying an electrical current to the affected area, causing the abnormal vessels to shrink and clot.

The procedure is typically performed using a specialized device that delivers an electrical current through a needle or probe. The intensity and duration of the electrical current can be adjusted to achieve the desired effect. Electrocoagulation may be used alone or in combination with other treatments, such as surgery or medication.

It's important to note that electrocoagulation is not without risks, including burns, infection, and scarring. It should only be performed by a qualified medical professional who has experience with the procedure.

Sick Sinus Syndrome (SSS) is a term used to describe a group of abnormal heart rhythm disturbances that originates in the sinoatrial node (the natural pacemaker of the heart). This syndrome is characterized by impaired functioning of the sinoatrial node, resulting in various abnormalities such as sinus bradycardia (abnormally slow heart rate), sinus arrest (complete cessation of sinus node activity), and/or sinoatrial exit block (failure of the electrical impulse to leave the sinus node and spread to the atria).

People with SSS may experience symptoms such as palpitations, dizziness, fatigue, shortness of breath, or syncope (fainting) due to inadequate blood supply to the brain caused by slow heart rate. The diagnosis of SSS is typically made based on the patient's symptoms and the results of an electrocardiogram (ECG), Holter monitoring, or event recorder that shows evidence of abnormal sinus node function. Treatment options for SSS may include lifestyle modifications, medications, or implantation of a pacemaker to regulate the heart rate.

Atrial flutter is a type of abnormal heart rhythm or arrhythmia that originates in the atria - the upper chambers of the heart. In atrial flutter, the atria beat too quickly, usually between 250 and 350 beats per minute, which is much faster than the normal resting rate of 60 to 100 beats per minute.

This rapid beating causes the atria to quiver or "flutter" instead of contracting effectively. As a result, blood may not be pumped efficiently into the ventricles - the lower chambers of the heart - which can lead to reduced cardiac output and symptoms such as palpitations, shortness of breath, fatigue, dizziness, or chest discomfort.

Atrial flutter is often caused by underlying heart conditions, such as coronary artery disease, hypertension, valvular heart disease, or congenital heart defects. It can also be a complication of cardiac surgery or other medical procedures. In some cases, atrial flutter may occur without any apparent underlying cause, which is known as lone atrial flutter.

Treatment for atrial flutter typically involves medications to control the heart rate and rhythm, electrical cardioversion to restore a normal heart rhythm, or catheter ablation to destroy the abnormal electrical pathways in the heart that are causing the arrhythmia. In some cases, surgical intervention may be necessary to treat atrial flutter.

The refractory period, electrophysiological, refers to the time interval during which a cardiac or neural cell is unable to respond to a new stimulus immediately after an action potential has been generated. This period is divided into two phases: the absolute refractory period and the relative refractory period.

During the absolute refractory period, the cell cannot be re-stimulated, regardless of the strength of the stimulus, due to the rapid inactivation of voltage-gated sodium channels that are responsible for the rapid depolarization during an action potential. This phase is crucial for maintaining the unidirectional conduction of electrical impulses and preventing the occurrence of re-entry circuits, which can lead to life-threatening arrhythmias in the heart or hyperexcitability in neural tissue.

The relative refractory period follows the absolute refractory period and is characterized by a reduced excitability of the cell. During this phase, a stronger than normal stimulus is required to elicit an action potential due to the slower recovery of voltage-gated sodium channels and the partial activation of potassium channels, which promote repolarization. The duration of both the absolute and relative refractory periods varies depending on the cell type, its physiological state, and other factors such as temperature and pH.

In summary, the electrophysiological refractory period is a fundamental property of excitable cells that ensures proper electrical signaling and prevents uncontrolled excitation or re-entry circuits.

The ultimobranchial body is a term used in human embryology to refer to a vestigial structure present during fetal development. It is the remnant of the fifth pharyngeal pouch, which eventually forms a part of the thyroid gland called the parafollicular or C cells. These cells are responsible for producing calcitonin, a hormone that helps regulate calcium levels in the body.

It's important to note that the term 'ultimobranchial body' is not commonly used in modern medical literature, and the structure it refers to is typically just referred to as the parafollicular cells or C cells of the thyroid gland.

Benzoylarginine-2-Naphthylamide is a synthetic substance that is used in laboratory settings as a reagent for the detection and measurement of certain enzymes, specifically proteases such as trypsin. It is a colorless to pale yellow crystalline powder that is soluble in water and alcohol. When treated with an enzyme that can cleave it, such as trypsin, it produces a colored product that can be measured and used to quantify the enzyme's activity. This compound is not used for medical purposes in humans or animals.

Tachycardia is a heart rate that is faster than normal when resting. In adults, a normal resting heart rate is typically between 60 and 100 beats per minute (bpm). Tachycardia is generally considered to be a heart rate of more than 100 bpm.

Ectopic atrial tachycardia (EAT) is a type of supraventricular tachycardia (SVT), which means that the abnormal rapid heartbeats originate in the atria, the upper chambers of the heart. EAT is caused by an ectopic focus, or an abnormal electrical focus outside of the sinoatrial node (the heart's natural pacemaker). This ectopic focus can be located in one of the pulmonary veins or in other atrial tissue.

EAT may present with symptoms such as palpitations, lightheadedness, shortness of breath, chest discomfort, or syncope (fainting). In some cases, EAT may not cause any symptoms and can be an incidental finding on an electrocardiogram (ECG) or Holter monitor.

The diagnosis of EAT is typically made based on the ECG findings, which show a regular narrow QRS complex tachycardia with P waves that are inverted in the inferior leads and often dissociated from the QRS complexes. Treatment options for EAT include observation, pharmacologic therapy, cardioversion, or catheter ablation.

Factor XI, also known as plasma thromboplastin antecedent (PTA) or antihemophilic factor C, is a protein involved in blood coagulation. It is one of the factors in the intrinsic pathway of coagulation, which is activated when blood comes into contact with negatively charged surfaces, such as damaged blood vessels.

When Factor XI is activated (usually by thrombin or activated Factor XII), it activates more Factor XI and also activates Factor IX, leading to the formation of a complex that converts Factor X to its active form, Factor Xa. This ultimately leads to the formation of a fibrin clot and helps to stop bleeding.

Deficiencies in Factor XI can lead to an increased risk of bleeding, although the severity of the bleeding disorder can vary widely among individuals with Factor XI deficiency. Treatment for Factor XI deficiency typically involves replacement therapy with fresh frozen plasma or recombinant Factor XI concentrate.

Electrophysiology is a branch of medicine that deals with the electrical activities of the body, particularly the heart. In a medical context, electrophysiology studies (EPS) are performed to assess abnormal heart rhythms (arrhythmias) and to evaluate the effectiveness of certain treatments, such as medication or pacemakers.

During an EPS, electrode catheters are inserted into the heart through blood vessels in the groin or neck. These catheters can record the electrical activity of the heart and stimulate it to help identify the source of the arrhythmia. The information gathered during the study can help doctors determine the best course of treatment for each patient.

In addition to cardiac electrophysiology, there are also other subspecialties within electrophysiology, such as neuromuscular electrophysiology, which deals with the electrical activity of the nervous system and muscles.

An artificial pacemaker is a medical device that uses electrical impulses to regulate the beating of the heart. It is typically used when the heart's natural pacemaker, the sinoatrial node, is not functioning properly and the heart rate is too slow or irregular. The pacemaker consists of a small generator that contains a battery and electronic circuits, which are connected to one or more electrodes that are placed in the heart.

The generator sends electrical signals through the electrodes to stimulate the heart muscle and cause it to contract, thereby maintaining a regular heart rhythm. Artificial pacemakers can be programmed to deliver electrical impulses at a specific rate or in response to the body's needs. They are typically implanted in the chest during a surgical procedure and can last for many years before needing to be replaced.

Artificial pacemakers are an effective treatment for various types of bradycardia, which is a heart rhythm disorder characterized by a slow heart rate. Pacemakers can significantly improve symptoms associated with bradycardia, such as fatigue, dizziness, shortness of breath, and fainting spells.

The vagus nerve, also known as the 10th cranial nerve (CN X), is the longest of the cranial nerves and extends from the brainstem to the abdomen. It has both sensory and motor functions and plays a crucial role in regulating various bodily functions such as heart rate, digestion, respiratory rate, speech, and sweating, among others.

The vagus nerve is responsible for carrying sensory information from the internal organs to the brain, and it also sends motor signals from the brain to the muscles of the throat and voice box, as well as to the heart, lungs, and digestive tract. The vagus nerve helps regulate the body's involuntary responses, such as controlling heart rate and blood pressure, promoting relaxation, and reducing inflammation.

Dysfunction in the vagus nerve can lead to various medical conditions, including gastroparesis, chronic pain, and autonomic nervous system disorders. Vagus nerve stimulation (VNS) is a therapeutic intervention that involves delivering electrical impulses to the vagus nerve to treat conditions such as epilepsy, depression, and migraine headaches.

Radio waves are not a medical term, but rather a type of electromagnetic radiation with frequencies ranging from about 30 kilohertz (kHz) to 300 gigahertz (GHz). They have longer wavelengths and lower frequencies than other types of electromagnetic radiation such as microwaves, infrared light, visible light, ultraviolet light, X-rays, and gamma rays.

In the medical field, radio waves are used in various diagnostic and therapeutic applications, including:

* Diagnostic imaging: Magnetic resonance imaging (MRI) uses radio waves in combination with a strong magnetic field to generate detailed images of internal organs and tissues.
* Radiation therapy: High-energy radio waves are used to destroy cancer cells or shrink tumors in radiation therapy.
* Cardiac ablation: Radiofrequency ablation is a medical procedure that uses radio waves to destroy small areas of heart tissue that cause abnormal heart rhythms.

It's important to note that while radio waves have many medical applications, they are not themselves a medical term or condition.

Atrioventricular (AV) block is a disorder of the electrical conduction system of the heart that causes a delay or interruption in the transmission of electrical signals from the atria (the upper chambers of the heart) to the ventricles (the lower chambers of the heart). This results in an abnormal heart rhythm, also known as an arrhythmia.

There are three degrees of AV block:

1. First-degree AV block: In this type of AV block, there is a delay in the conduction of electrical signals from the atria to the ventricles, but all signals are eventually conducted. This condition may not cause any symptoms and is often discovered during a routine electrocardiogram (ECG).
2. Second-degree AV block: In this type of AV block, some electrical signals from the atria are not conducted to the ventricles. There are two types of second-degree AV block: Mobitz type I and Mobitz type II. Mobitz type I is characterized by a progressive prolongation of the PR interval (the time between the electrical activation of the atria and ventricles) until a QRS complex (which represents the electrical activation of the ventricles) is dropped. Mobitz type II is characterized by a constant PR interval with occasional non-conducted P waves.
3. Third-degree AV block: In this type of AV block, no electrical signals are conducted from the atria to the ventricles. The atria and ventricles beat independently of each other, resulting in a slow heart rate (bradycardia) and an irregular rhythm. This condition can be life-threatening if not treated promptly.

The causes of AV block include aging, heart disease, medications, and certain medical conditions such as hypothyroidism and Lyme disease. Treatment depends on the severity of the condition and may include medication, a pacemaker, or surgery.

Anti-arrhythmia agents are a class of medications used to treat abnormal heart rhythms or arrhythmias. These drugs work by modifying the electrical activity of the heart to restore and maintain a normal heart rhythm. There are several types of anti-arrhythmia agents, including:

1. Sodium channel blockers: These drugs slow down the conduction of electrical signals in the heart, which helps to reduce rapid or irregular heartbeats. Examples include flecainide, propafenone, and quinidine.
2. Beta-blockers: These medications work by blocking the effects of adrenaline on the heart, which helps to slow down the heart rate and reduce the force of heart contractions. Examples include metoprolol, atenolol, and esmolol.
3. Calcium channel blockers: These drugs block the entry of calcium into heart muscle cells, which helps to slow down the heart rate and reduce the force of heart contractions. Examples include verapamil and diltiazem.
4. Potassium channel blockers: These medications work by prolonging the duration of the heart's electrical cycle, which helps to prevent abnormal rhythms. Examples include amiodarone and sotalol.
5. Digoxin: This drug increases the force of heart contractions and slows down the heart rate, which can help to restore a normal rhythm in certain types of arrhythmias.

It's important to note that anti-arrhythmia agents can have significant side effects and should only be prescribed by a healthcare professional who has experience in managing arrhythmias. Close monitoring is necessary to ensure the medication is working effectively and not causing any adverse effects.

Purkinje fibers are specialized cardiac muscle fibers that are located in the subendocardial region of the inner ventricular walls of the heart. They play a crucial role in the electrical conduction system of the heart, transmitting electrical impulses from the bundle branches to the ventricular myocardium, which enables the coordinated contraction of the ventricles during each heartbeat.

These fibers have a unique structure that allows for rapid and efficient conduction of electrical signals. They are larger in diameter than regular cardiac muscle fibers, have fewer branching points, and possess more numerous mitochondria and a richer blood supply. These features enable Purkinje fibers to conduct electrical impulses at faster speeds, ensuring that the ventricles contract simultaneously and forcefully, promoting efficient pumping of blood throughout the body.

I believe there might be a misunderstanding in your question. "Dogs" is not a medical term or condition. It is the common name for a domesticated carnivore of the family Canidae, specifically the genus Canis, which includes wolves, foxes, and other extant and extinct species of mammals. Dogs are often kept as pets and companions, and they have been bred in a wide variety of forms and sizes for different purposes, such as hunting, herding, guarding, assisting police and military forces, and providing companionship and emotional support.

If you meant to ask about a specific medical condition or term related to dogs, please provide more context so I can give you an accurate answer.

Cardiac arrhythmias are abnormal heart rhythms that result from disturbances in the electrical conduction system of the heart. The heart's normal rhythm is controlled by an electrical signal that originates in the sinoatrial (SA) node, located in the right atrium. This signal travels through the atrioventricular (AV) node and into the ventricles, causing them to contract and pump blood throughout the body.

An arrhythmia occurs when there is a disruption in this electrical pathway or when the heart's natural pacemaker produces an abnormal rhythm. This can cause the heart to beat too fast (tachycardia), too slow (bradycardia), or irregularly.

There are several types of cardiac arrhythmias, including:

1. Atrial fibrillation: A rapid and irregular heartbeat that starts in the atria (the upper chambers of the heart).
2. Atrial flutter: A rapid but regular heartbeat that starts in the atria.
3. Supraventricular tachycardia (SVT): A rapid heartbeat that starts above the ventricles, usually in the atria or AV node.
4. Ventricular tachycardia: A rapid and potentially life-threatening heart rhythm that originates in the ventricles.
5. Ventricular fibrillation: A chaotic and disorganized electrical activity in the ventricles, which can be fatal if not treated immediately.
6. Heart block: A delay or interruption in the conduction of electrical signals from the atria to the ventricles.

Cardiac arrhythmias can cause various symptoms, such as palpitations, dizziness, shortness of breath, chest pain, and fatigue. In some cases, they may not cause any symptoms and go unnoticed. However, if left untreated, certain types of arrhythmias can lead to serious complications, including stroke, heart failure, or even sudden cardiac death.

Treatment for cardiac arrhythmias depends on the type, severity, and underlying causes. Options may include lifestyle changes, medications, cardioversion (electrical shock therapy), catheter ablation, implantable devices such as pacemakers or defibrillators, and surgery. It is essential to consult a healthcare professional for proper evaluation and management of cardiac arrhythmias.

The heart ventricles are the two lower chambers of the heart that receive blood from the atria and pump it to the lungs or the rest of the body. The right ventricle pumps deoxygenated blood to the lungs, while the left ventricle pumps oxygenated blood to the rest of the body. Both ventricles have thick, muscular walls to generate the pressure necessary to pump blood through the circulatory system.

An action potential is a brief electrical signal that travels along the membrane of a nerve cell (neuron) or muscle cell. It is initiated by a rapid, localized change in the permeability of the cell membrane to specific ions, such as sodium and potassium, resulting in a rapid influx of sodium ions and a subsequent efflux of potassium ions. This ion movement causes a brief reversal of the electrical potential across the membrane, which is known as depolarization. The action potential then propagates along the cell membrane as a wave, allowing the electrical signal to be transmitted over long distances within the body. Action potentials play a crucial role in the communication and functioning of the nervous system and muscle tissue.

Heart rate is the number of heartbeats per unit of time, often expressed as beats per minute (bpm). It can vary significantly depending on factors such as age, physical fitness, emotions, and overall health status. A resting heart rate between 60-100 bpm is generally considered normal for adults, but athletes and individuals with high levels of physical fitness may have a resting heart rate below 60 bpm due to their enhanced cardiovascular efficiency. Monitoring heart rate can provide valuable insights into an individual's health status, exercise intensity, and response to various treatments or interventions.

Connexins are a family of proteins that form the structural units of gap junctions, which are specialized channels that allow for the direct exchange of small molecules and ions between adjacent cells. These channels play crucial roles in maintaining tissue homeostasis, coordinating cellular activities, and enabling communication between cells. In humans, there are 21 different connexin genes that encode for these proteins, with each isoform having unique properties and distributions within the body. Mutations in connexin genes have been linked to a variety of human diseases, including hearing loss, skin disorders, and heart conditions.

Body Surface Potential Mapping (BSPM) is a non-invasive medical technique used to record and analyze the electrical activity of the heart from the surface of the body. It involves placing multiple electrodes on the skin of the chest, back, and limbs to measure the potential differences between these points during each heartbeat. This information is then used to create a detailed, visual representation of the electrical activation pattern of the heart, which can help in the diagnosis and evaluation of various cardiac disorders such as arrhythmias, myocardial infarction, and ventricular hypertrophy.

The BSPM technique provides high-resolution spatial and temporal information about the cardiac electrical activity, making it a valuable tool for both clinical and research purposes. It can help identify the origin and spread of abnormal electrical signals in the heart, which is crucial for determining appropriate treatment strategies. Overall, Body Surface Potential Mapping is an important diagnostic modality that offers unique insights into the electrical functioning of the heart.

Lymph node excision is a surgical procedure in which one or more lymph nodes are removed from the body for the purpose of examination. This procedure is often conducted to help diagnose or stage various types of cancer, as malignant cells may spread to the lymphatic system and eventually accumulate within nearby lymph nodes.

During a lymph node excision, an incision is made in the skin overlying the affected lymph node(s). The surgeon carefully dissects the tissue surrounding the lymph node(s) to isolate them from adjacent structures before removing them. In some cases, a sentinel lymph node biopsy may be performed instead, where only the sentinel lymph node (the first lymph node to which cancer cells are likely to spread) is removed and examined.

The excised lymph nodes are then sent to a laboratory for histopathological examination, which involves staining and microscopic evaluation of the tissue to determine whether it contains any malignant cells. The results of this examination can help guide further treatment decisions and provide valuable prognostic information.

Follow-up studies are a type of longitudinal research that involve repeated observations or measurements of the same variables over a period of time, in order to understand their long-term effects or outcomes. In medical context, follow-up studies are often used to evaluate the safety and efficacy of medical treatments, interventions, or procedures.

In a typical follow-up study, a group of individuals (called a cohort) who have received a particular treatment or intervention are identified and then followed over time through periodic assessments or data collection. The data collected may include information on clinical outcomes, adverse events, changes in symptoms or functional status, and other relevant measures.

The results of follow-up studies can provide important insights into the long-term benefits and risks of medical interventions, as well as help to identify factors that may influence treatment effectiveness or patient outcomes. However, it is important to note that follow-up studies can be subject to various biases and limitations, such as loss to follow-up, recall bias, and changes in clinical practice over time, which must be carefully considered when interpreting the results.

Heart neoplasms are abnormal growths or tumors that develop within the heart tissue. They can be benign (noncancerous) or malignant (cancerous). Benign tumors, such as myxomas and rhabdomyomas, are typically slower growing and less likely to spread, but they can still cause serious complications if they obstruct blood flow or damage heart valves. Malignant tumors, such as angiosarcomas and rhabdomyosarcomas, are fast-growing and have a higher risk of spreading to other parts of the body. Symptoms of heart neoplasms can include shortness of breath, chest pain, fatigue, and irregular heart rhythms. Treatment options depend on the type, size, and location of the tumor, and may include surgery, radiation therapy, or chemotherapy.

A microelectrode is a small electrode with dimensions ranging from several micrometers to a few tens of micrometers in diameter. They are used in various biomedical applications, such as neurophysiological studies, neuromodulation, and brain-computer interfaces. In these applications, microelectrodes serve to record electrical activity from individual or small groups of neurons or deliver electrical stimuli to specific neural structures with high spatial resolution.

Microelectrodes can be fabricated using various materials, including metals (e.g., tungsten, stainless steel, platinum), metal alloys, carbon fibers, and semiconductor materials like silicon. The design of microelectrodes may vary depending on the specific application, with some common types being sharpened metal wires, glass-insulated metal microwires, and silicon-based probes with multiple recording sites.

The development and use of microelectrodes have significantly contributed to our understanding of neural function in health and disease, enabling researchers and clinicians to investigate the underlying mechanisms of neurological disorders and develop novel therapies for conditions such as Parkinson's disease, epilepsy, and hearing loss.

Cardiovascular models are simplified representations or simulations of the human cardiovascular system used in medical research, education, and training. These models can be physical, computational, or mathematical and are designed to replicate various aspects of the heart, blood vessels, and blood flow. They can help researchers study the structure and function of the cardiovascular system, test new treatments and interventions, and train healthcare professionals in diagnostic and therapeutic techniques.

Physical cardiovascular models may include artificial hearts, blood vessels, or circulation systems made from materials such as plastic, rubber, or silicone. These models can be used to study the mechanics of heart valves, the effects of different surgical procedures, or the impact of various medical devices on blood flow.

Computational and mathematical cardiovascular models use algorithms and equations to simulate the behavior of the cardiovascular system. These models may range from simple representations of a single heart chamber to complex simulations of the entire circulatory system. They can be used to study the electrical activity of the heart, the biomechanics of blood flow, or the distribution of drugs in the body.

Overall, cardiovascular models play an essential role in advancing our understanding of the human body and improving patient care.

The tricuspid valve is the heart valve that separates the right atrium and the right ventricle in the human heart. It is called "tricuspid" because it has three leaflets or cusps, which are also referred to as flaps or segments. These cusps are named anterior, posterior, and septal. The tricuspid valve's function is to prevent the backflow of blood from the ventricle into the atrium during systole, ensuring unidirectional flow of blood through the heart.

In medical terms, the heart is a muscular organ located in the thoracic cavity that functions as a pump to circulate blood throughout the body. It's responsible for delivering oxygen and nutrients to the tissues and removing carbon dioxide and other wastes. The human heart is divided into four chambers: two atria on the top and two ventricles on the bottom. The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs, while the left side receives oxygenated blood from the lungs and pumps it out to the rest of the body. The heart's rhythmic contractions and relaxations are regulated by a complex electrical conduction system.

A sentinel lymph node biopsy is a surgical procedure used in cancer staging to determine if the cancer has spread beyond the primary tumor to the lymphatic system. This procedure involves identifying and removing the sentinel lymph node(s), which are the first few lymph nodes to which cancer cells are most likely to spread from the primary tumor site.

The sentinel lymph node(s) are identified by injecting a tracer substance (usually a radioactive material and/or a blue dye) near the tumor site. The tracer substance is taken up by the lymphatic vessels and transported to the sentinel lymph node(s), allowing the surgeon to locate and remove them.

The removed sentinel lymph node(s) are then examined under a microscope for the presence of cancer cells. If no cancer cells are found, it is unlikely that the cancer has spread to other lymph nodes or distant sites in the body. However, if cancer cells are present, further lymph node dissection and/or additional treatment may be necessary.

Sentinel lymph node biopsy is commonly used in the staging of melanoma, breast cancer, and some types of head and neck cancer.

The myocardium is the middle layer of the heart wall, composed of specialized cardiac muscle cells that are responsible for pumping blood throughout the body. It forms the thickest part of the heart wall and is divided into two sections: the left ventricle, which pumps oxygenated blood to the rest of the body, and the right ventricle, which pumps deoxygenated blood to the lungs.

The myocardium contains several types of cells, including cardiac muscle fibers, connective tissue, nerves, and blood vessels. The muscle fibers are arranged in a highly organized pattern that allows them to contract in a coordinated manner, generating the force necessary to pump blood through the heart and circulatory system.

Damage to the myocardium can occur due to various factors such as ischemia (reduced blood flow), infection, inflammation, or genetic disorders. This damage can lead to several cardiac conditions, including heart failure, arrhythmias, and cardiomyopathy.

In the field of medicine, "time factors" refer to the duration of symptoms or time elapsed since the onset of a medical condition, which can have significant implications for diagnosis and treatment. Understanding time factors is crucial in determining the progression of a disease, evaluating the effectiveness of treatments, and making critical decisions regarding patient care.

For example, in stroke management, "time is brain," meaning that rapid intervention within a specific time frame (usually within 4.5 hours) is essential to administering tissue plasminogen activator (tPA), a clot-busting drug that can minimize brain damage and improve patient outcomes. Similarly, in trauma care, the "golden hour" concept emphasizes the importance of providing definitive care within the first 60 minutes after injury to increase survival rates and reduce morbidity.

Time factors also play a role in monitoring the progression of chronic conditions like diabetes or heart disease, where regular follow-ups and assessments help determine appropriate treatment adjustments and prevent complications. In infectious diseases, time factors are crucial for initiating antibiotic therapy and identifying potential outbreaks to control their spread.

Overall, "time factors" encompass the significance of recognizing and acting promptly in various medical scenarios to optimize patient outcomes and provide effective care.

Adenosine is a purine nucleoside that is composed of a sugar (ribose) and the base adenine. It plays several important roles in the body, including serving as a precursor for the synthesis of other molecules such as ATP, NAD+, and RNA.

In the medical context, adenosine is perhaps best known for its use as a pharmaceutical agent to treat certain cardiac arrhythmias. When administered intravenously, it can help restore normal sinus rhythm in patients with paroxysmal supraventricular tachycardia (PSVT) by slowing conduction through the atrioventricular node and interrupting the reentry circuit responsible for the arrhythmia.

Adenosine can also be used as a diagnostic tool to help differentiate between narrow-complex tachycardias of supraventricular origin and those that originate from below the ventricles (such as ventricular tachycardia). This is because adenosine will typically terminate PSVT but not affect the rhythm of VT.

It's worth noting that adenosine has a very short half-life, lasting only a few seconds in the bloodstream. This means that its effects are rapidly reversible and generally well-tolerated, although some patients may experience transient symptoms such as flushing, chest pain, or shortness of breath.

The atrioventricular node or AV node electrically connects the heart's atria and ventricles to coordinate beating in the top of ... This activates the AV node. The atrioventricular node delays impulses by approximately 0.09s. This delay in the cardiac pulse ... November 2007). "Abnormal Conduction and Morphology in the Atrioventricular Node of Mice With Atrioventricular Canal-Targeted ... Atrioventricular nodal re-entry tachycardia, which is caused by a dual AV node physiology and AVNRT can only occur in people ...
Current then passes from the atria through the atrioventricular node and into the bundle of His, from which it travels along ... AV node), the "junction" between atria and ventricles. Under normal conditions, the heart's sinoatrial node(SA node) determines ... When this happens, the heart's atrioventricular node or bundle of His can take over as the pacemaker, starting the electrical ... If there is a blockage between the AV node and the SA node, the atria may not contract at all. Junctional rhythm can be ...
The atrioventricular node position differs from other fowl. It is located in the endocardium of the atrial surface of the right ... 10 (1): 21-7. Parto P. (2012). "The Structure of the Atrioventricular Node in the Heart of the Female Laying Ostrich (Struthio ... The AV node connects the atrial and ventricular chambers. It functions to carry the electrical impulse from the atria to the ... The sinoatrial node shows a small concentration of Purkinje fibers, however, continuing through the conducting pathway of the ...
A dromotrope affects atrioventricular node (AV node) conduction. A positive dromotrope increases AV nodal conduction, and a ... such as by changing the rhythm produced by the sinoatrial node. Positive chronotropes increase heart rate; negative ...
In this circumstance, an alteration in the F-wave to QRS relationship is seen.[citation needed] Atrioventricular node ... However, this AV node stimulation can cause a delay in subsequent AV conduction by modifying the AV node's subsequent ... As a result of the rapid atrial rate, some of the atrial activity fails to get through the AV node in an antegrade direction ... because the retrograde impulse from the PVC does not completely penetrate the AV node. ...
It is also known as mesothelioma of the atrioventricular node. It may present as a cardiac arrhythmia or as sudden cardiac ... tumour of the atrioventricular nodal region is a very rare tumour of the heart in the region of the atrioventricular node. ... Cystic tumours of the atrioventricular nodal region, true to their name, have cystic spaces, which are lined by a single layer ... Apr 2000). "Cystic tumour of the atrioventricular nodal region: report of a case successfully treated with surgery". Heart. 83 ...
"Fatal Lyme carditis and endodermal heterotopia of the atrioventricular node". Postgraduate Medical Journal. 66 (772): 134-6. ... Lyme carditis in 19-87% of people adversely impacts the heart's electrical conduction system, causing atrioventricular block ...
... also has important parasympathetic effects, particularly on the atrioventricular node. While it does increase the ... The slowed AV node gives the ventricles more time to fill before contracting. This negative chronotropic effect is synergistic ... The refractory period of the atria and ventricles is decreased, while it increases in the sinoatrial and AV nodes. A less ... The conduction velocity increases in the atria, but decreases in the AV node. The effect upon Purkinje fibers and ventricles is ...
SA node). The impulse initially causes both atria to contract, then activates the atrioventricular node (AV node), which is ... Rhythms produced by an ectopic focus in the atria, or by the atrioventricular node, are the least dangerous dysrhythmias; but ... Bradyarrhythmias are due to sinus node dysfunction or atrioventricular conduction disturbances. Arrhythmias are due to problems ... These cells are found in the conduction system of the heart and include the SA node, AV node, Bundle of His, and Purkinje ...
Ludwig Aschoff (1866-1942), German pathologist, discoverer of the Aschoff body and the Atrioventricular node in the heart. Max ... discoverer of the Atrioventricular node. Donald Teare (1911-1979), British pathologist. Jacques-René Tenon (1724-1816), French ... Louis-Antoine Ranvier (1835-1922), French physician, pathologist, anatomist and histologist, discoverer of nodes of Ranvier. ...
These abnormal rhythms start from either the atria or atrioventricular node. They are generally due to one of two mechanisms: ... Sinoatrial node reentrant tachycardia (SANRT) is caused by a reentry circuit localised to the SA node, resulting in a P-wave of ... Cryoablation is a newer treatment involving the AV node directly. SVT involving the AV node is often a contraindication to ... at the atrioventricular node, which allows only a proportion of the fast impulses to pass through to the ventricles. An ...
Pacemaker cells in the sinoatrial node, and atrioventricular node are smaller and conduct at a relatively slow rate between the ... Other pacemaker cells are found in the atrioventricular node (secondary pacemaker). Pacemaker cells carry the impulses that are ... ISBN 0-13-193480-5. Kashou AH, Basit H, Chhabra L (January 2020). "Physiology, Sinoatrial Node (SA Node)". StatPearls. PMID ... They are located in the sinoatrial node (the primary pacemaker) positioned on the wall of the right atrium, near the entrance ...
In contrast, expression is low in the sinoatrial node and atrioventricular node. Within the heart, a transmural expression ...
Additionally, high degrees of transcription occur in the adrenal cortex and atrioventricular node. The Human Protein Atlas ... CLIP4 mRNA expression occurs largely in the adrenal cortex and atrioventricular node. The literature encompassing CLIP4's ...
The apex of Koch's triangle is the location of the atrioventricular node. During atrial systole, blood flows from the atria to ... Chordae tendineae are relaxed because the atrioventricular valves are forced open. When the ventricles of the heart contract in ... The chordae tendineae connect the atrioventricular valves (tricuspid and mitral), to the papillary muscles within the ...
In the atrioventricular node, the resting potential is lowered, which facilitates conduction. This is seen as a shortened PR- ... It causes tachycardia by blocking vagal effects on the sinoatrial node. Acetylcholine hyperpolarizes the sinoatrial node; this ...
The atrioventricular nodal branch is a coronary artery that supplies arterial blood to the atrioventricular node, which is ... The atrioventricular nodal branch supplies the atrioventricular node, allowing for excitation of the ventricles. Coronary ... In approximately 2% of people, the vascular supply to the atrioventricular node arises from both the right coronary artery and ... The artery of the atrioventricular node: an anatomic study based on 38 injection-dissections. Surg Radiol Anat 1996;18:183-187 ...
"Preoperative secundum atrial septal defect with coexisting sinus node and atrioventricular node dysfunction". Circulation. 65 ( ... Both of these can cause an increased distance of internodal conduction from the SA node to the AV node. In addition to the PR ... but it is more commonly classified as an atrioventricular septal defect. Ostium primum defects are less common than ostium ...
The atrioventricular node (AV node) is another node in the cardiac conduction system. This is located between the atria and the ... The sinoatrial node (SA node) is located in the posterior aspect of the right atrium, next to the superior vena cava. This is a ... The blood in the atria is pumped into the heart ventricles through the atrioventricular mitral and tricuspid heart valves. ... left atrioventricular valve) for pumping out through the aorta for systemic circulation. High in the upper part of the left ...
... and septal leaflet of the right atrioventricular valve. It is anatomically significant because the atrioventricular node is ... "Koch's Triangle and the Atrioventricular Node in Ebstein's Anomaly: Implications for Catheter Ablation". Revista Española de ...
Together they discovered and described the atrioventricular node (AV node, Aschoff-Tawara node). Numerous travels abroad, to ...
These electrical pathways contain the sinoatrial node, the atrioventricular node, and the Purkinje fibers. (Exceptions such as ... The electrical activity of ventricular systole is coordinated by the atrioventricular node, which is a discrete collection of ... The sinoatrial node (S-A Node) is the heart's natural pacemaker, issuing electrical signaling that travels through the heart ... the signals of which then coalesce at the atrioventricular node, there to be organized to provide a rhythmic electrical pulse ...
Widran J, Lev M (December 1951). "The dissection of the atrioventricular node, bundle and bundle branches in the human heart". ...
When it is administered intravenously, adenosine causes transient heart block in the atrioventricular (AV) node. This is ... This includes any re-entrant arrhythmias that require the AV node for the re-entry, e.g., AV reentrant tachycardia (AVRT) and ... Because of the effects of adenosine on AV node-dependent SVTs, adenosine is considered a class V antiarrhythmic agent. When ... and do not involve the AV node as part of the re-entrant circuit, are not typically converted by adenosine. However, the ...
From there, the electrical stimulus is transmitted via internodal pathways to the atrioventricular (AV) node. After a brief ... Problems arise when this pathway creates an electrical circuit that bypasses the AV node. The AV node is capable of slowing the ... thus bypassing the atrioventricular node. About 60% of people with the electrical problem developed symptoms, which may include ... electrical activity that is initiated in the SA node travels through the accessory pathway, as well as through the AV node to ...
... "atrioventricular connecting system". The atrioventricular connecting system starts in the atrioventricular node, moves into the ... The monograph revealed the existence of the atrioventricular node and the function of Purkinje cells. It was used by Arthur ... Encouraged by their initial success and inspired by Tawara's discovery of the atrioventricular node, Keith and Flack extended ... Silverman, M. E.; Hollman, A. (1 October 2007). "Discovery of the sinus node by Keith and Flack: on the centennial of their ...
AVNRT occurs when a reentrant circuit forms within or just next to the atrioventricular node. The circuit usually involves two ... The fundamental mechanism of AVNRT is a presence of a dual atrioventricular node physiology (present in half of the population ... which acts as a re-entrant circuit within the atrioventricular node. This can take several forms. "Typical", "common", or "slow ... These pathways are formed from tissue that behaves very much like the AV node, and some authors regard them as part of the AV ...
The signal travels from the SA node to the ventricles through the atrioventricular node (AV node). In an AV block, this ... Normally, the sinoatrial node (SA node) produces an electrical signal to control the heart rate. ... The electrical signal then travels to the AV node located on the lower portion of the interatrial septum. At the AV node there ... Atrioventricular block (AV block) is a type of heart block that occurs when the electrical signal traveling from the atria, or ...
The signal then travels to the atrioventricular node. This is found at the bottom of the right atrium in the atrioventricular ... The right coronary artery also supplies blood to the atrioventricular node (in about 90% of people) and the sinoatrial node (in ... Tawara's discovery of the atrioventricular node prompted Arthur Keith and Martin Flack to look for similar structures in the ... These generate an electric current that causes the heart to contract, traveling through the atrioventricular node and along the ...
... node and propagating to the atrioventricular (AV) node, the signal is conducted both to the ventricle and back to the SA node ... However, if the atrial beat is premature enough, it may reach the atrioventricular node during its refractory period, in which ... This can be either a premature atrial contraction or a premature impulse from the atrioventricular node. SVES should be viewed ... Typically, the atrial impulse propagates normally through the atrioventricular node and into the cardiac ventricles, resulting ...
The atrioventricular node or AV node electrically connects the hearts atria and ventricles to coordinate beating in the top of ... This activates the AV node. The atrioventricular node delays impulses by approximately 0.09s. This delay in the cardiac pulse ... November 2007). "Abnormal Conduction and Morphology in the Atrioventricular Node of Mice With Atrioventricular Canal-Targeted ... Atrioventricular nodal re-entry tachycardia, which is caused by a dual AV node physiology and AVNRT can only occur in people ...
... is a form of re-entrant rhythm within the region of the atrioventricular (AV) node. Re-entrant rhythms account for most ... Atrioventricular Node Reentry Supraventricular Tachycardia * Sections Atrioventricular Node Reentry Supraventricular ... Atrioventricular Node Reentry Supraventricular Tachycardia. Low voltage bridge in atrioventricular node reentry tachycardia ( ... encoded search term (Atrioventricular Node Reentry Supraventricular Tachycardia) and Atrioventricular Node Reentry ...
Synonyms and keywords: AVN; AV node; junctional node; AV junction; Aschoff-Tawara node ... The atrioventricular node is an area of specialized tissue between the atria and the ventricles of the heart, which conducts ... Sinoatrial node (SA node). References. *↑ ACC/AHA/ESC Guidelines for the Management of Patients with Atrial Fibrillation - ... The atrioventricular node delays impulses for ~0.1 second before allowing impulses through to the His-Purkinje conduction ...
Imaging of the atrioventricular node using optical coherence tomography. Meghna Gupta, Andrew M. Rollins, Joseph A. Izatt, Igor ... Imaging of the atrioventricular node using optical coherence tomography. / Gupta, Meghna; Rollins, Andrew M.; Izatt, Joseph A. ... Gupta, M., Rollins, A. M., Izatt, J. A., & Efimov, I. R. (2002). Imaging of the atrioventricular node using optical coherence ... Gupta, M, Rollins, AM, Izatt, JA & Efimov, IR 2002, Imaging of the atrioventricular node using optical coherence tomography, ...
One-dimensional mathematical model of the atrioventricular node including atrio-nodal, nodal, and nodal-his cells (Nodal Cell) ... One-dimensional mathematical model of the atrioventricular node including atrio-nodal, nodal, and nodal-his cells, S. Inada, J. ... One-dimensional mathematical model of the atrioventricular node including atrio-nodal, nodal, and nodal-his cells (Nodal-His ... One-dimensional mathematical model of the atrioventricular node including atrio-nodal, nodal, and nodal-his cells (Atrio-Nodal ...
Atrioventricular (AV) node ablation is a cardiac catheterisation procedure to treat atrial fibrillation, which prevents the ... Before the procedure, several tests are undertaken and in all cases patients are fitted with a pacemaker prior to the AV node ...
Translations of ATRIOVENTRICULAR NODE from English to Persian and index of ATRIOVENTRICULAR NODE in the bilingual analogic ... Definition and meaning of ATRIOVENTRICULAR NODE. Translation (Wikipedia). Atrioventricular node. گره دهلیزی-بطنی ...
The catheter-based radiofrequency ablation procedure of the atrio-ventricular node is aimed at patients suffering from ... What are the effects of the ablation procedure for modulating the atrio-ventricular node?. The "ablate-and-pace" approach is ... How is the ablation procedure performed for the atrio-ventricular node modulation? After local anesthesia in the femoral site, ... What is the ablation procedure for modulating the atrio-ventricular node? The catheter-based radiofrequency ablation procedure ...
Cardiac atrial fibrillation clinics have a multidisciplinary team that takes referrals and provides teaching for patients with a new or previous diagnosis of Atrial Fibrillation or Atrial Flutter.
A spatially extended model of the human atrioventricular node. Wallman, M. & Sandberg, F., 2017 Jan 1, 2017 Computing in ... Multilevel Modeling of the Atrioventricular Node for Personalized Treatment of Atrial Fibrillation. *Sandberg, Frida ( ... Preliminary results from clinical validation study of a method for non-invasive assessment of atrioventricular node ...
Current then passes from the atria through the atrioventricular node and into the bundle of His, from which it travels along ... AV node), the "junction" between atria and ventricles. Under normal conditions, the hearts sinoatrial node(SA node) determines ... When this happens, the hearts atrioventricular node or bundle of His can take over as the pacemaker, starting the electrical ... If there is a blockage between the AV node and the SA node, the atria may not contract at all. Junctional rhythm can be ...
The Atrioventricular valves perform a very important task in the heart as they prevents blood from flowing back into the atria ... This signal then reaches the atrioventricular node, which delays the impulse before transmitting it to the ventricles through ... D. Sinoatrial node. Explanation. The sinoatrial node is considered the functional pacemaker of the heart because it initiates ... This is the correct answer because the AV node is located near the SA node in the heart, and the electrical impulse generated ...
keywords = "Atrioventricular node, Morphometry, P cells, Sinus node, T cells",. author = "G{\o}mez-Torres, {F. A.} and ... The region of the sinus and atrioventricular nodes was sectioned serially, and the block of tissue removed for study. The ... The region of the sinus and atrioventricular nodes was sectioned serially, and the block of tissue removed for study. The ... Histological and morphometric study of the components of the sinus and atrioventricular nodes in horses and dogs. / Gómez- ...
If the sinoatrial (SA) node fails, then at what rate (depolarizations per minute) can the atrioventricular (AV) node depolarize ... If the sinoatrial (SA) node fails, then at what rate (depolarizations per minute) can the atrioventricular (AV) node depolarize ...
Atrioventricular (AV) node (a-tree-oh-ven-TRICK-ular):. Node of specialized tissue lying near the bottom of the right atrium ... The system includes another node, the atrioventricular or AV node, located near the bottom of the right atrium just above the ... Sinoatrial (SA) node (sigh-no-A-tree-al):. Node of specialized tissue lying in the upper area of the right atrium that fires an ... A small node of specialized muscle tissue located in the upper area of the right atrium is called the sinoatrial or SA node. ...
Inferior Extensions of the Atrioventricular Node. Anderson RH, Hikspoors JP, Tretter JT, Macías Y, Spicer DE, Lamers WH, ...
AVN atrioventricular node bpm beats per minute CARE-HF Cardiac REsynchronization in Heart Failure CDSR Cochrane Database of ... Abbreviations: AF = atrial fibrillation; AVN = atrioventricular node; KQ = key question; PICOTS = populations, interventions, ... the 2006 ACC/AHA/ESC Guidelines recommend ablation of the atrioventricular node (AVN) in conjunction with permanent pacemaker ... Assessment of atrioventricular junction ablation and VVIR pacemaker versus pharmacological treatment in patients with heart ...
47%, odds ratio 2.12, p = 4.9 × 10−26). Corrected sinus node recovery time (CSRT) was longer and left atrial volume index (LAVI ... These findings strongly implicate rs6817105 minor allele in sinus node dysfunction and left atrial enlargement. ... The atrial effective refractory period and atrioventricular node effective refractory period were also measured. ... Relationship between sinus node function and PITX2 have been reported in animals. Wang et al. reported that PITX2 positively ...
Only verapamil and diltiazem delay atrioventricular conduction or cause sinus node depression at doses in common use clinically ... In vitro, all CCB subclasses both depress sinus node activity and slow atrioventricular conduction. ...
The signals go through the upper heart chambers to the atrioventricular (AV) node. Next, the signals pass into the lower heart ... They pass through a pathway between the upper and lower heart chambers called the atrioventricular (AV) node. The movement of ... Sick sinus syndrome. The sinus node sets the pace of the heart. If the node doesnt work properly, the heart rate may switch ... Sick sinus syndrome can be caused by scarring near the sinus node that slows, disrupts or blocks heartbeat signals. The ...
The signal travels through the hearts upper chambers to the atrioventricular (AV) node. The signal then passes into the lower ... Inside the upper right heart chamber is a group of cells called the sinus node. The sinus node makes the signals that starts ... The AV node is flooded with signals trying to get through to the lower heart chambers. This causes a fast and irregular heart ... Next, the signals arrive at a group of cells called the AV node, where they usually slow down. The signals then go to the lower ...
... or interruption of atrial impulse conduction to the ventricles through the atrioventricular node (AVN). ... Second-degree atrioventricular (AV) block, or second-degree heart block, is a disorder characterized by disturbance, delay, ... Second-degree block at the level of the atrioventricular node (AVN) may be due to digoxin, beta-blockers, or calcium channel ... Second-Degree Atrioventricular Block. Mobitz II atrioventricular (AV) block with intermittent periods of 2:1 AV block. If only ...
Patients with sinus node dysfunction causing bradycardia and patients with bradycardia or syncope due to atrioventricular ... Electrophysiologic effects of flecainide acetate on sinus node function, anomalous atrioventricular connections, and pacemaker ... seem to affect normal sinus node function but in patients with sinus node dysfunction an increase of the corrected sinus node ... In patients with evidence of dual atrioventricular node pathway physiology, flecainide has shown to prolong mainly the ...
The mechanism of this type of tachycardia is believed to be circus movement re-entry involving the atrioventricular node and an ... Because of its selective class III antiarrhythmic effect, dofetilide has no effect on atrioventricular conduction or sinus node ... Sustained atrioventricular re-entrant tachycardia was induced in all 51 patients before dofetilide infusion. The tachycardia ... Atrioventricular re-entrant tachycardia is currently treated with various pharmacological agents. While class I antiarrhythmic ...
... is a disorder of the cardiac conduction system where there is no conduction through the atrioventricular node (AVN). Therefore ... Third-degree atrioventricular (AV) block, also referred to as third-degree heart block or complete heart block, ... Third-Degree Atrioventricular Block (Complete Heart Block) * Sections Third-Degree Atrioventricular Block (Complete Heart Block ... encoded search term (Third-Degree Atrioventricular Block (Complete Heart Block)) and Third-Degree Atrioventricular Block ( ...
The electrical current then goes to the atrioventricular (AV) node, which signals the ventricles to contract. The current then ...
Then the impulses travel down to the atrioventricular (or AV) node, which acts as a kind of relay station. From here, the ... During systole, the atrioventricular valves close, creating the first sound (the lub) of a heartbeat. When the atrioventricular ... This node is called the pacemaker of the heart because it sets the rate of the heartbeat and causes the rest of the heart to ... The sinus (or sinoatrial) node is a small area of tissue in the wall of the right atrium. It sends out an electrical signal to ...
Then the impulses travel down to the atrioventricular (or AV) node, which acts as a kind of relay station. From here, the ... During systole, the atrioventricular valves close, creating the first sound (the lub) of a heartbeat. When the atrioventricular ... This node is called the pacemaker of the heart because it sets the rate of the heartbeat and causes the rest of the heart to ... The sinus (or sinoatrial) node is a small area of tissue in the wall of the right atrium. It sends out an electrical signal to ...
  • The cardiac conduction system (and AV node part of it) coordinates myocyte mechanical activity. (wikipedia.org)
  • A wave of excitation spreads out from the sinoatrial node through the atria along specialized conduction channels. (wikipedia.org)
  • An important property that is unique to the AV node is decremental conduction, in which the more frequently the node is stimulated the slower it conducts. (wikipedia.org)
  • This is the property of the AV node that prevents rapid conduction to the ventricle in cases of rapid atrial rhythms, such as atrial fibrillation or atrial flutter. (wikipedia.org)
  • This property is important because loss of the conduction system before the AV node should still result in pacing of the ventricles by the slower pacemaking ability of the AV node. (wikipedia.org)
  • Atrioventricular conduction disease (AV block) describes impairment of the electrical continuity between the atria and ventricles. (wikipedia.org)
  • The slow pathway(s) approach the compact AV node from inferiorly and have a relatively longer conduction time and an ERP that typically is short when compared to the fast pathway ERP. (medscape.com)
  • The atrioventricular node delays impulses for ~0.1 second before allowing impulses through to the His-Purkinje conduction system, which spreads impulses to the ventricular walls. (wikidoc.org)
  • citation needed] In junctional rhythm, however, the sinoatrial node does not control the heart's rhythm - this can happen in the case of a block in conduction somewhere along the pathway described above, or in sick sinus syndrome, or many other situations. (wikipedia.org)
  • Depending on where the rhythm originates in the AV node, the atria can contract before ventricular contraction due to retrograde conduction, during ventricular contraction, or after ventricular contraction. (wikipedia.org)
  • The lower cell density in any of the cardiac nodes, especially in P cells of sinus node, can decrease electrical conduction within the nodes and in the internodal tracts, which would reflect the presence of cardiac arrhythmias derived from poor conduction, even in morphologically normal hearts. (unab.edu.co)
  • Outcomes in patients with dual antegrade conduction in the atrioventricular node: insights from a multicentre observational study. (ikf.hamburg)
  • In vitro, all CCB subclasses both depress sinus node activity and slow atrioventricular conduction. (medscape.com)
  • Only verapamil and diltiazem delay atrioventricular conduction or cause sinus node depression at doses in common use clinically. (medscape.com)
  • Because of its selective class III antiarrhythmic effect, dofetilide has no effect on atrioventricular conduction or sinus node function. (bmj.com)
  • Third-degree atrioventricular (AV) block, also referred to as third-degree heart block or complete heart block (CHB), is an abnormal heart rhythm resulting from a defect in the cardiac conduction system in which there is no conduction through the atrioventricular node (AVN), leading to complete dissociation of the atria and ventricles. (medscape.com)
  • Following intra-atrial conduction to the area of the lower intra-atrial septum, this wavefront reaches the inputs to the atrioventricular node (AVN). (medscape.com)
  • Cardiac Conduction Abnormalities: May worsen sinus node dysfunction and atrioventricular (AV) block, especially in patients taking other sympatholytic drugs. (nih.gov)
  • The heart rate during atrial fibrillation (AF) is highly dependent on the conduction properties of the atrioventricular (AV) node, which can be affected using β-blockers or calcium channel blockers, often chosen empirically. (lu.se)
  • We have created a mathematical network model of the AV node where continuous estimation of the refractory period and conduction delay from 24-hour ambulatory ECGs from patients with permanent AF (n=59) was achieved using a problem-specific genetic algorithm. (lu.se)
  • The proposed method enables analysis of circadian variation in AV node conduction delay and refractoriness from 24h ambulatory ECG, which can be used to monitor and possibly predict the effect of rate control drugs. (lu.se)
  • The transition of atrioventricular blockade of the II-III degree to the 1st degree or complete normalization of atrioventricular conduction at the sinus rhythm. (who.int)
  • [ 1 ] The impulse is then conducted through the atrium to the atrioventricular junction from where, after a delay, the electrical signal is propagated to the ventricles along bundles of specialized conduction tissue to the distal Purkinje fibers, which ramify among the contractile myocardium. (medscape.com)
  • The atrioventricular node delays impulses by approximately 0.09s. (wikipedia.org)
  • During AVNRT, the circuit typically involves both a fast and a slow pathway within the region of the AV node, which allows the impulses to proceed down the His-Purkinje system to the ventricles while simultaneously proceeding in a retrograde fashion to depolarize the atria and reenter the node. (medscape.com)
  • Atrioventricular (AV) node ablation is a cardiac catheterisation procedure to treat atrial fibrillation, which prevents the upper chambers (atria) sending faulty electrical impulses to the lower chambers (ventricles). (dorsetheartclinic.co.uk)
  • Junctional rhythm describes an abnormal heart rhythm resulting from impulses coming from a locus of tissue in the area of the atrioventricular node(AV node), the "junction" between atria and ventricles. (wikipedia.org)
  • In a typical heartbeat, a tiny cluster of cells at the sinus node sends out electrical signals, called impulses. (mayoclinic.org)
  • Then the impulses travel down to the atrioventricular (or AV) node , which acts as a kind of relay station. (kidshealth.org)
  • These nerve-like conduits receive impulses from a modified muscle structure called the atrioventricular node. (microscopyu.com)
  • Impulses from the upper chambers of the heart are relayed by this node to large bundles of Purkinje fibers referred to as the Bundle of His . (microscopyu.com)
  • Electrical impulses move from the sinoatrial node down to the bundle branches, stimulating a normal heartbeat in which the ventricles contract slightly later than the atria. (medlineplus.gov)
  • A specialized cluster of cells called the atrioventricular node conducts electrical impulses from the heart's upper chambers (the atria) to the lower chambers (the ventricles). (cooperhealth.org)
  • Impulses move through the atrioventricular node during each heartbeat, stimulating the ventricles to contract slightly later than the atria. (cooperhealth.org)
  • Cholinesterase inhibitors may have vagotonic effects on the sinoatrial and atrioventricular nodes manifesting as bradycardia or heart block ( 5.2 ). (nih.gov)
  • Cystic tumour of atrioventricular nodal region (CTAVN) CTAVN is of endodermal origin and occurs exclusively in the area of the AV node, tricuspid valve, and interatrial septum. (wikipedia.org)
  • The right atrioventricular valve is the tricuspid valve . (daviddarling.info)
  • The left-sided atrioventricular valve, in this case, the tricuspid valve, showed apical displacement of the septal valve suggesting Ebstein's anomaly. (scirp.org)
  • The catheter-based radiofrequency ablation procedure of the atrio-ventricular node is aimed at patients suffering from persistent atrial fibrillation, in which drug therapies for rhythm and heart rate control are not effective. (af-ablation.org)
  • It occurs commonly in patients with sinus node dysfunction. (wikipedia.org)
  • 1/600 cardiology patients over the age of 65 have sinus node dysfunction. (wikipedia.org)
  • These findings strongly implicate rs6817105 minor allele in sinus node dysfunction and left atrial enlargement. (nature.com)
  • The blood supply of the AV node is from the atrioventricular nodal branch. (wikipedia.org)
  • Atrioventricular nodal re-entry tachycardia, which is caused by a dual AV node physiology and AVNRT can only occur in people with it, however almost half of the population have it, though only a few of them will develop AVNRT at some point in life. (wikipedia.org)
  • it is not synonymous with AV node reentrant tachycardia (AVNRT) because the incidental finding of dual AV nodal physiology does not predict AVNRT in children and adolescents after successful accessory pathway ablation. (medscape.com)
  • The blood supply of the AV node is from a branch of the right coronary artery in 85% to 90% of individuals (a branch off of the posterolateral artery , the AV nodal artery , and from a branch of the left circumflex artery in 10% to 15% of individuals. (wikidoc.org)
  • After premature stimulation, atrioventricular nodal reentry could occur. (cellml.org)
  • After slow pathway ablation or block of the L-type Ca(2+) current, atrioventricular nodal reentry was abolished. (cellml.org)
  • The AV node lies at the lower back section of the interatrial septum near the opening of the coronary sinus, and conducts the normal electrical impulse from the atria to the ventricles. (wikipedia.org)
  • The atrioventricular node is an area of specialized tissue between the atria and the ventricles of the heart , which conducts the normal electrical impulse from the atria to the ventricles. (wikidoc.org)
  • People with Wolff-Parkinson-White syndrome are born with an extra connection in the heart, called an accessory pathway, that allows electrical signals to bypass the atrioventricular node and move from the atria to the ventricles faster than usual. (cooperhealth.org)
  • Junctional bradycardia is a rhythm that still originates in the AV node or bundle of His, but simply beats at a rate less than 40 beats per minute. (wikipedia.org)
  • Enlarged including sinus bradycardia and grade of C. ulcerans -infected pigs may lead cervical lymph nodes were palpable I atrioventricular block, were present. (cdc.gov)
  • Symptomatic sinus bradycardia or bradycardia due to atrioventricular blockade, including transient. (who.int)
  • When this happens, the heart's atrioventricular node or bundle of His can take over as the pacemaker, starting the electrical signal that causes the heart to beat. (wikipedia.org)
  • The signal travels through the heart's upper chambers to the atrioventricular (AV) node. (mayoclinic.org)
  • These signals begin in a specialized cluster of cells called the sinoatrial node (the heart's natural pacemaker) located in the heart's upper chambers (the atria). (medlineplus.gov)
  • Atrioventricular node reentrant tachycardia (AVNRT) is a form of reentrant rhythm within the region of the atrioventricular (AV) node. (medscape.com)
  • Nonsustained atrioventricular node reentry tachycardia (AVNRT). (medscape.com)
  • OBJECTIVE To assess the efficacy and safety of intravenous dofetilide in preventing induction of atrioventricular re-entrant tachycardia. (bmj.com)
  • Fifty one patients with electrically inducible atrioventricular re-entrant tachycardia were allocated to one of five doses of dofetilide (1.5, 3, 6, 9, and 15 μg/kg), two thirds of the dofetilide dose being given over a 15 minute loading period and the remainder over a 45 minute maintenance period. (bmj.com)
  • MAIN OUTCOME MEASURE Responders were defined as patients in whom dofetilide prevented reinduction of atrioventricular re-entrant tachycardia at the end of the infusion. (bmj.com)
  • In non-responders, dofetilide increased the cycle length of induced atrioventricular re-entrant tachycardia. (bmj.com)
  • CONCLUSIONS Dofetilide shows promise as an agent for the prevention of atrioventricular re-entrant tachycardia in patients without structural heart disease. (bmj.com)
  • Atrioventricular re-entrant tachycardia is currently treated with various pharmacological agents. (bmj.com)
  • 14-16 However, to date there have been no studies on the dose dependent effects of dofetilide on atrioventricular re-entrant tachycardia. (bmj.com)
  • Our goal in this study was to assess the efficacy of intravenous dofetilide, in five different dosing regimens, for treating patients with inducible atrioventricular re-entrant tachycardia, by determining its ability to prevent reinduction of the tachycardia. (bmj.com)
  • What is the ablation procedure for modulating the atrio-ventricular node? (af-ablation.org)
  • How is the ablation procedure performed for the atrio-ventricular node modulation? (af-ablation.org)
  • The signals go through the upper heart chambers to the atrioventricular (AV) node. (mayoclinic.org)
  • Sick sinus syndrome can be caused by scarring near the sinus node that slows, disrupts or blocks heartbeat signals. (mayoclinic.org)
  • Since the AV node doesn't prevent all of these chaotic signals from entering the lower chambers, the heart beats faster and irregularly. (mayoclinic.org)
  • The electrical current then goes to the atrioventricular (AV) node , which signals the ventricles to contract. (healthline.com)
  • From there, a group of cells called the atrioventricular node carries the electrical signals to another cluster of cells called the bundle of His. (medlineplus.gov)
  • The Atrioventricular valves perform a very important task in the heart as they prevents blood from flowing back into the atria from the ventricles. (proprofs.com)
  • Why don't you take up the test below and get to see what you know about atrioventricular valves? (proprofs.com)
  • The valves between the atria and ventricles are called atrioventricular valves (also called cuspid valves), while those at the bases of the large vessels leaving the ventricles are called semilunar valves . (daviddarling.info)
  • When the ventricles contract, atrioventricular valves close to prevent blood from flowing back into the atria. (daviddarling.info)
  • The cardiac nodes are the source of the electrical impulse that is transmitted to the heart, the aim of this work is study the histological and morphometric characteristics of the different components of the sinus and atrioventricular nodes in horses and dogs that help to know the physiopathology of these nodes. (unab.edu.co)
  • The normal cardiac impulse of the vertebrate heart originates in the pacemaker cells of the sinoatrial node, located in the right atrium. (medscape.com)
  • The AV node receives two inputs from the right atrium: posteriorly, via the crista terminalis, and anteriorly, via the interatrial septum. (wikipedia.org)
  • Node of specialized tissue lying near the bottom of the right atrium that fires an electrical impulse across the ventricles, causing them to contract. (encyclopedia.com)
  • The sinus (or sinoatrial) node is a small area of tissue in the wall of the right atrium. (kidshealth.org)
  • After modulation of the atrioventricular node in general, an intrinsic escapement rhythm at the junctional level can remain, the frequency of which is generally between 30 and 50 bpm. (af-ablation.org)
  • Anything that impairs the SA node can potentially lead to a junctional rhythm. (wikipedia.org)
  • Current then passes from the atria through the atrioventricular node and into the bundle of His, from which it travels along Purkinje fibers to reach and depolarize the ventricles. (wikipedia.org)
  • In types IA and IB, the heart block originates in the bundle branch, and in type II, the heart block originates in the atrioventricular node. (medlineplus.gov)
  • If the sinoatrial (SA) node fails, then at what rate (depolarizations per minute) can the atrioventricular (AV) node depolarize? (assignmentblock.com)
  • The electrical activity of sinus rhythm originates in the sinoatrial node and depolarizes the atria. (wikipedia.org)
  • The region of the sinus and atrioventricular nodes was sectioned serially, and the block of tissue removed for study. (unab.edu.co)
  • Second-degree atrioventricular (AV) block in the asymptomatic patient does not require any specific therapy in the prehospital setting. (medscape.com)
  • Second-degree block at the level of the atrioventricular node (AVN) may be due to digoxin, beta-blockers, or calcium channel blockers. (medscape.com)
  • Traditionally, atrioventricular (AV) block can be classified into first-, second-, and third-degree block. (medscape.com)
  • Transient atrioventricular block of II-III degree or permanent block of II degree. (who.int)
  • Before the procedure, several tests are undertaken and in all cases patients are fitted with a pacemaker prior to the AV node ablation procedure. (dorsetheartclinic.co.uk)
  • If pharmacological therapy is insufficient or associated with side effects, the 2006 ACC/AHA/ESC Guidelines recommend ablation of the atrioventricular node (AVN) in conjunction with permanent pacemaker implantation to control heart rate. (ahrq.gov)
  • This node is called the pacemaker of the heart because it sets the rate of the heartbeat and causes the rest of the heart to contract in its rhythm. (kidshealth.org)
  • Through this venous access, a scaler catheter is advanced near the atrium ventricular node (compact part). (af-ablation.org)
  • In a typical heart, a tiny group of cells at the sinus node sends out an electrical signal. (mayoclinic.org)
  • The SA node has a property called "automaticity", which means it can generate an electrical spark, called an action potential, all by itself. (cosmosmagazine.com)
  • The sinoatrial (sinus) node (1) initiates an electrical impulse that flows through the right and left atria (2), making them contract. (msdmanuals.com)
  • When the electrical impulse reaches the atrioventricular node (3), it is delayed slightly. (msdmanuals.com)
  • The AV node's normal intrinsic firing rate without stimulation (such as that from the SA node) is 40-60 times/minute. (wikipedia.org)
  • The AV node receives two inputs from the atria: posteriorly via the crista terminalis , and anteriorly via the interatrial septum . (wikidoc.org)
  • [ 3 ] Multiple atypical AVNRT circuits using rightward and leftward inferior extensions of the AV node have been described. (medscape.com)
  • Retrograde, or inverted, P waves refers to the depolarization from the AV node back towards the SA node. (wikipedia.org)
  • In the heart, normal impulse initiation begins in the sinoatrial node (SAN). (medscape.com)
  • In this procedure, an area of the heart called the atrioventricular - or AV - node is destroyed. (epnet.com)
  • If there is a blockage between the AV node and the SA node, the atria may not contract at all. (wikipedia.org)
  • In four-chamber view, atrioventricular discordance was detected with severe tricuspid regurgitation (vena contracta = 9.3 mm) and dysplasia of the mitral leaflets with severe mitral regurgitation (vena contracta = 10.3 mm) by color Doppler, Video 1. (scirp.org)
  • When the RCA supplies the AV node, the coronary system is said to be "right dominant," and when the AV node is supplied by the LCX, the system is "left dominant. (wikidoc.org)
  • The left atrioventricular valve is the mitral valve (also called the bicuspid valve). (daviddarling.info)
  • Although action potential models have been developed for most regions of the heart, there is no model for the atrioventricular node (AVN). (cellml.org)
  • Using these models, together with models for the sinoatrial node (SAN) and atrial muscle, we have developed a one-dimensional (1D) multicellular model including the SAN and AVN. (cellml.org)