The cardiac conduction system is a complex network of cells that together orchestrate the rhythmic and coordinated depolarization of the heart. The molecular mechanisms regulating the specification and patterning of cells that form this conductive network are largely unknown. Studies in avian models have suggested that components of the cardiac conduction system arise from progressive recruitment of cardiomyogenic progenitors, potentially influenced by inductive effects from the neighboring coronary vasculature. However, relatively little is known about the process of conduction system development in mammalian species, especially in the mouse, where even the histological identification of the conductive network remains problematic. We have identified a line of transgenic mice where lacZ reporter gene expression delineates the developing and mature murine cardiac conduction system, extending proximally from the sinoatrial node to the distal Purkinje fibers. Optical mapping of cardiac electrical ...
Disease of the CCS is common and can result from congenital abnormalities or can be acquired later in life. As such, a better understanding of the basic biology and molecular pathways underlying cardiac conduction tissue development, maintenance, and function may have significant impact on the clinical care of patients with conduction disorders.. In this report, we show that Hop is highly expressed in the adult CCS of mice and modulates cardiac conduction system function. Hop is a transcriptional target of Nkx2-5, which is also highly expressed in the CCS12 and is required for normal development and maintenance of adult cardiac conduction tissue.4,5 Mutations in Nkx2-5 are associated with proximal conduction system defects in humans and with congenital heart disease.6 Tissue-specific inactivation of Nkx2-5 in adult mouse hearts leads to progressive loss of conduction tissue and downregulation of Hop.4 Our data suggest that Hop is robustly expressed in the adult CCS. However, unlike Nkx2-5, Hop ...
The development and structure of the cardiac conduction system, including the known molecular and cellular factors that regulate development of the conduction system are outlined. Part II includes...
Purpose Nocturnal cardiac conduction abnormalities are commonly observed in patients with sleep-disordered breathing (SDB). However, few population-based studies have examined the association between...
As to a mechanism other than ionic remodeling for AF associated with heart failure, Lie et al18 showed in canine hearts that the key change appeared to involve alteration in local atrial conduction properties caused by interstitial fibrosis. Thus, what are some of the known local conduction abnormalities associated with atrial fibrosis?. We found premature stimuli to initiate anisotropic conduction abnormalities that led to reentry within areas as small as 1.6 mm2 in aging human atrial bundles.19,20 There were 2 major underling conduction disturbances that produced the reentry in such a small area: one was a very low effective velocity with conduction across fibers (as low as in the AV node), and the other was decremental conduction to failure. Similar conduction disturbances and reentry did not occur in younger adult bundles. These conduction differences were related to the aging proliferation of connective tissue septa. In the younger adult bundles collagenous septa were short and scattered, ...
Many transgenic mouse models show abnormal conduction with PR prolongation and/or high-degree heart block.8-11 Decreased connexin abundance accounts for the conduction defect in some8-11 but not all21,23 transgenic models. Slow conduction in the ventricle could lead to reentrant arrhythmias and sudden death. Here, we report the first in vivo model in which chronic dephosphorylation of cardiac connexins, without loss of expression, is associated with defective cardiac conduction.. Conductance of connexin40 gap junctions in cultured cells is increased on phosphorylation of human connexin40 by PKA.12 Consistent with phosphorylation controlling gap-junction conductance, dephosphorylation of connexin40 is associated with defective atrial conduction in RTEF-1 mice. As in connexin40-null mice,5,6 burst pacing induces atrial arrhythmias in RTEF-1 mice. With age, RTEF-1 mice develop spontaneous atrial arrhythmias that probably contribute to progressive atrial dilatation. The extent of PR prolongation is ...
A method and system for ascertaining the condition of the hearts conduction system in a patient treated for congestive heart failure with pacing therapy. In accordance with the invention, changes in ventricular activation patterns are monitored over time in order to detect changes in the hearts conduction system that may occur due to physiological regeneration of conduction pathways. The activation patterns are reflected by electrogram signals detected from different ventricular locations. By measuring the difference in conduction times of an excitation impulse traveling from the AV node to the different ventricular locations, a parameter representative of the hearts conduction system is obtained that may be used to adjust the pacing therapy in accordance therewith.
Individual compartments of cardiac conduction system (CCS) became functional in order which correlates with cardiac morphogenesis. Ventricular CCS compartments mature with ventricular septation and it is accompanied by shift of activation pattern from primitive base to apex, which follows blood flow
Proarrhythmic properties of antiarrhythmic drugs have been known for years. Some antiarrhythmics have the ability to slow electric conduction through the myocardium, which is the mechanism proposed to cause sudden cardiac arrhythmic death reported in selected patients taking antiarrhythmics (IC) agents. This is usually observed in the presence of structural abnormalities predisposing to reentry phenomena.1 In addition, IC antiarrhythmic drugs are the most powerful sodium channel blockers. As a consequence, they produce the strongest myocardial conduction delay and therefore prolongation in conduction intervals.2. The prolongation of conduction intervals is dose-dependent, and it can reach up to 20% of baseline duration at maximum doses of propafenone.3 Higher prolongations should worry clinicians because it can reflect a risk of drug toxicity and proarrhythmic effects. Dose reduction may be sufficient to deal with mild prolongations, often observed in the face of poor metabolizers or drug ...
Cardiac conduction system - Animation A network of specialized muscle cells is found in the hearts walls. These muscle cells send signals to the rest of the heart muscle causing a contraction. This group of muscle cells is called the cardiac conduction system. The main parts of the system are the SA node, AV node, bundle of HIS, bundle branches, and Purkinje fibers. Lets follow a signal through the contraction process. The SA node starts the sequence by causing the atrial muscles to contract. Thats why doctors sometimes call it the anatomical pacemaker. Next, the signal travels to the AV node, through the bundle of HIS, down the bundle branches, and through the Purkinje fibers, causing the ventricles to contract. This signal creates an electrical current that can be seen on a graph called an electrocardiogram, or EKG. Doctors use an EKG to see how well the cardiac conduction system works. Any changes on the EKG can mean serious problems. ...
Fingerprint Dive into the research topics of Impact of intracellular delay, immune activation delay and nonlinear incidence on viral dynamics. Together they form a unique fingerprint. ...
ALA Reduces diabetes-induced myocardial activation of JNK and P38. Total protein was obtained from the hearts of STZ-induced diabetic rats and vehicle rats. Pho
Despite remarkable progress in the past few years, the gene regulatory networks underlying formation and function of the cardiac conduction system (CCS) remain incompletely understood. Transcription factors such as NXK2.5 and TBX2/3/5 that control various aspects of heart development have emerged as key regulators of cardiac conduction gene expression and function. By showing alterations in the structure of the atrioventricular node (AVN) and the electrophysiological parameters of mice harboring a mutated GATA-binding factor 6 (GATA6) protein, Liu et al1 add a new player to the growing list of transcription factors involved in cardiac rhythm regulation. This finding provides insight that will help advance efforts to elucidate the pathogenesis of cardiac rhythm disturbances.. Article see p 284. In human, cardiac rhythm disturbances are a major cause of mortality and morbidity from fetal to adult life. They can develop in response to numerous conditions, such as electrolyte imbalance, ...
Conduction System. Development of the conduction system. Cardiomyocytes form the conduction system of the heart. Molecular genetic studies have revealed the requirement of a functional network of transcription factors to determine whether a myocardial precursor cell turns into either a working cell or a cell belonging to the conduction system. Contrary to previous assumptions, the conduction system itself has no neural crest influence during development. The innervation of the conduction system in adults though is ensured through cardiac ganglia originating from the neural crest. In embryos, the innervation of this system is still missing.. Cells located in the caudal heart tube, derived from the common cardinal vein or right sinus venosus in the sinoatrial region, differentiate to form the sinoatrial node near the left venous valve. This node acts as a pacemaking component of the cardiac conduction pathway. During early development, the entire sinus venosus has a pacemaker activity. In fact, ...
The bundle of His or His bundle is a collection of heart muscle cells specialized for electrical conduction. As part of the electrical conduction system of the heart, it transmits the electrical impulses from the AV node (located between the atria and the ventricles) to the point of the apex of the fascicular branches via the bundle branches. The fascicular branches then lead to the Purkinje fibers, which provide electrical conduction to the ventricles, causing the cardiac muscle of the ventricles to contract at a paced interval. The bundle of His is an important part of the electrical conduction system of the heart, as it transmits impulses from the atrioventricular node, located at the inferior end of the interatrial septum, to the ventricles of the heart. The intrinsic rate of the bundle of His is 20 or less beats per minute. The bundle of His branches into the left and the right bundle branches, which run along the interventricular septum. The left bundle branch further divides into the left ...
The present study has several limitations. First, electrograms from the region of Kochs triangle were recorded simultaneously only from two atrial sites (i.e., the His bundle recording site and the CS orifice), and simple broad anatomic terms (anterior, middle and posterior) were used to define the anatomic sites of the atrial septum. More detailed endocardial mapping over the triangle of Koch or along the tendon of Todaro (31)may have yielded more information about the exact FP and SP location. However, unlike intraoperative computerized mapping (32), fluoroscopy cannot identify precise endocardial anatomy and, therefore, the presumed FP or SP location has only been inferential, even with the use of decapolar electrode catheters-an inherent limitation to clinical electrophysiologic study. In addition, mapping restricted over the right endocardial surface can only provide limited information about the excitation of the AV node and the atrial septum, which are three-dimensional subendocardial ...
Introduction to the 12-lead ECG Gustav Schellack SASOCP Workshop 10 March 2012 © G Schellack; 2012 Electrocardiogram (ECG)    The ECG is a graphic recording of the electrical activity of the heart, at a specific moment in time. Note: Electrical activity refers to the depolarisation and repolarisation of the atria and ventricles. Note: The ECG cannot tell us anything about the mechanical activity (i.e. contraction and relaxation) of the myocardium. Cardiac Conduction System Anatomical orientation: Figure 1: (Marquette Electronics, 1996) (From: Yanowitz, FG. The Alan E Lindsay ECG Learning Centre in Cyberspace [homepage on the Internet]. c2012. Available from: http://library.med.utah.edu/kw/ecg/index.html.) The Cardiac Impulse Originates from the SA-node (in the RA) Spreads through both atria [virtually] simultaneously RA Spreads through both atria [virtually] simultaneously LA Activates both ventricles via the His-Purkinje network; first the septum from (L) to (R), then the RV, then ...
The Conduction System of the Mammlian Heart: An Anatomico-Histological Study of the Atrioventricular Bundle and the Purkinje Fibers (Cardiopulmonary Medicine from I*C*P*, Volume 234) http://s10.postimg.org/ws4yk7trt/The_Conduction_System_of_the_Mammlian_Heart.jpg By Sunao Tawara, Kozo Suma, Munehiro Shimada Hardcover: 256 pages Publisher: WSP Co; 1 edition (September 1, 1998) Language: English ISBN-10: 1860941168 ISBN-13: 978-1860941160
TY - JOUR. T1 - Anisotropic conduction in the myocardium due to fibrosis: the effect of texture on wave propagation. AU - Nezlobinsky, T.. AU - Solovyova, O.. AU - Panfilov, A. V.. PY - 2020/1/21. Y1 - 2020/1/21. KW - FRACTIONATED ELECTROGRAMS. KW - CARDIAC FIBROSIS. KW - ORGANIZATION. KW - REENTRY. KW - HEART. KW - MODEL. KW - VF. UR - http://www.scopus.com/inward/record.url?scp=85078163392&partnerID=8YFLogxK. UR - https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=tsmetrics&SrcApp=tsm_test&DestApp=WOS_CPL&DestLinkType=FullRecord&KeyUT=000512142100002. U2 - 10.1038/s41598-020-57449-1. DO - 10.1038/s41598-020-57449-1. M3 - Article. AN - SCOPUS:85078163392. VL - 10. JO - Scientific Reports. JF - Scientific Reports. SN - 2045-2322. IS - 1. M1 - 764. ER - ...
Many cardiac excitation problems can be diagnosed from the information in a single lead of an electrocardiogram. The lead II electrocardiogram traces at the top of Figure 5-1 and 5-2 are identified as normal sinus rhythms based on the following characteristics: (1) the frequency of QRS complexes is approximately 1 per second, indicating a normal beating rate; (2) the shape of the QRS complex is normal for lead II and its duration is less than 120 ms, indicating rapid depolarization of the ventricles via normal conduction pathways; (3) each QRS complex is preceded by a P wave of proper configuration, indicating sinoatrial (SA) nodal origin of the excitation; (4) the PR interval is less than 200 ms, indicating proper conduction delay of the impulse propagation through the atrioventricular (AV) node; (5) the QT interval is less than half of the R-to-R interval, indicating normal ventricular repolarization; and (6) there are no extra P waves, indicating that no AV nodal conduction block is present. ...
Regular electrical activation waves in cardiac tissue lead to the rhythmic contraction and expansion of the heart that ensures blood supply to the whole body. Irregularities in the propagation of these activation waves can result in cardiac arrhythmias, like ventricular tachycardia (VT) and ventricular fibrillation (VF), which are major causes of death in the industrialised world. Indeed there is growing consensus that spiral or scroll waves of electrical activation in cardiac tissue are associated with VT, whereas, when these waves break to yield spiral- or scroll-wave turbulence, VT develops into life-threatening VF: in the absence of medical intervention, this makes the heart incapable of pumping blood and a patient dies in roughly two-and-a-half minutes after the initiation of VF. Thus studies of spiral- and scroll-wave dynamics in cardiac tissue pose important challenges for in vivo and in vitro experimental studies and for in silico numerical studies of mathematical models for cardiac tissue. A
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Learn about aberrant ventricular conduction (aberration, aberrancy), emphasis on causes, ECG characteristics, clinical implications, management.
Electrogram (EGM) terms pertain to invasive electrophysiologic recording of cardiac impulse conduction. Expand them at first mention. |
Electrogram (EGM) terms pertain to invasive electrophysiologic recording of cardiac impulse conduction. Expand them at first mention. |
Study cardiac conduction flashcards from alexandra colvin's class online, or in Brainscape's iPhone or Android app. ✓ Learn faster with spaced repetition.
Study of the cardiac conduction system at the macroscopic (layer-preparation, organometry), histological (layered serial histological sections), histochemical, immunohistochemical and ultrastructural ...
clinical significance from merely annoying to instantly life threatening. Antidysrhythmics include all xenobiotics that are used to treat any of these various dysrhythmias. The importance of dysrhythmia management in the modern practice of medicine cannot be overstated because dysrhythmias are among the most common causes of preventable sudden cardiac death.30,53 Despite an incomplete understanding of the underlying mechanisms of dysrhythmia formation, an abundance of antidysrhythmics have been developed, each attempting to alter specific electrophysiologic components of the cardiac impulse generating or conducting system. In addition to the predictable, mechanism-based adverse effect of each xenobiotic, unique and often unanticipated effects also occur.96 Experience with overdose of many of these xenobiotics is limited, and management is generally based on the underlying pharmacologic principles, existing case reports, and the experimental literature. ...
As cardiac impulse passes through the heart, electrical currents spread into tissue surrounding the heart and a small proportion spreads all the way to the s...
AXON - A long extension in the nerve. DENDRITES - Small parts of a cell. MYELIN - Sheath. The nervous system can coordinate a response to a stimulus, using nerve cells.. Nerve cells, or neurons are specialized cells that transmit electrical impulses around the body.. How are responses coordinated. 1. Specific receptors in a sense organ detect a stimulus.. 2. An electrical impulse is sent to the brain.. 3. The brain processes the information.. 4. An electrical impulse is sent to an effector (e.g. muscle or gland.). 5. The effector produces a response.. ...
The reentrant circuit is seen as a consequence of the inhomogeneity in refractoriness in Figure 24.2D. Such conditions (along with short refractory periods, and slow conduction) are found in ischemic myocardium. An examination of successive beats shows the position around which propagation takes place to shift continuously. The reason is that the cells in the region of the vortex during one cycle may show a large action potential (hence be part of the circulating wave) in the following cycle. In spite of this beat-to-beat variation the reentry in the case of tachycardia is relatively orderly and results in a regular rhythm. Random reentry, which characterizes fibrillation, is characterized by pathways whose size and location are continually changing. In addition, several independent wavefronts may be present simultaneously and interact with one another. The resulting rhythm is consequently relatively irregular and chaotic ...
The combination of the nonspecific F-type channels and the closing of K+ channels results in a steady depolarization when membrane potential is negative, these channels paired with the effects of T-type Ca+2 channels allow recurring depolarization following repolarization and therefore facilitate the pacemaker ...
The Cardiovascular & Blood Circulatory System Facts. Pictures of the circulatory, heart conduction system, arteries & blood vessels.
I left the room, wrote a thorough note and pondered the situation as I walked to get the programmer. Usually some other metabolic derangement assists us in stopping the heart of patients with pacemakers - we dont usually turn them off. The natural consequence of other confounding diseases work to cause a lack of oxygen, too much potassium, or another metabolic problem that disconnects the electrical activity from the mechanical. When the mechanical stops, it really doesnt matter what the electrical system does, since the pumping stops irrespective of the electrical impulses applied to the heart ...
สโมสรอินเตอร์ มิลาน ทีมชื่อดังแห่งเวทีกัลโช่ เซเรีย อิตาลี มีข่าวว่าพวกเขาทำการติดต่อไปหา เลโอนาร์โด้ ชาร์ดิม นายใหญ่ของสโมสรอาแอส โมนาโก ทีมในลีกเอิง ฝรั่งเศส เพื่อหวังคว้าตัวมาคุมทีมในซีซั่นหน้า หลังจากที่พวกเขา อดได้ อันโตนิโอ คอนเต้,เมาริซิโอ โปเช็ตติโน่ รวมไปถึง ดีเอโก้ ซิเมโอเน่ แน่นอนแล้ว และทีมงูใหญ่ ...
Looking for online definition of conduction system in the Medical Dictionary? conduction system explanation free. What is conduction system? Meaning of conduction system medical term. What does conduction system mean?
Loop recorder may detect cardiac conduction abnormalities in systemic sclerosis patients in European League Against Rheumatism (EULAR) 2016 Annual Congress | MIMS Malaysia
For patient information, click here Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mugilan Poongkunran M.B.B.S [2] Synonyms and Keywords: QRS prolongation; wide QRS; wide QRS complex; wide QRS complexes; IVCD; IVCDs; intraventricular conduction defect; non-specific intraventricular conduction delay; non-specific intraventricular conduction defect ...
The AV node receives two inputs from the atria: posteriorly via the crista terminalis, and anteriorly via the interatrial septum.[1] 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. 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. 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. The reason it is important to delay the cardiac impulse is to ensure that the atria have ejected their blood into the ventricles before the ventricles contract.[2] ...
The objective of the study was to evaluate the effect of ibutilide on canine cardiac sinoatrial and atrioventricular nodes (AVNs). For this purpose, 18 mongrel dogs were injected intravenously with ibutilide and the changes in heart rate, sinus node recovery time, and AVN were measured. Our data show that ibutilide administration caused significant suppression of the sinus atrial node, the peak response time was 20-30 min, and the heart rate was restored to pre-drug administration level. After receiving ibutilide, 1 animal had a 5 s sinus pause, and after 5 min of ibutilide administration, 1 dog showed 2:1 atrioventricular conduction. Therefore, it was concluded that ibutilide had a suppressive effect on the sinoatrial node and AVN. ...
Electrical conduction system of the heart: | | | |Electrical conduction system of the heart| | | ... World Heritage Encyclopedia, the aggregation of the largest online encyclopedias available, and the most definitive collection ever assembled.
Definition of Purkinje system in the Legal Dictionary - by Free online English dictionary and encyclopedia. What is Purkinje system? Meaning of Purkinje system as a legal term. What does Purkinje system mean in law?
Disturbances of interatrial conduction have been proposed as one of the contributing mechanisms of postoperative atrial fibrillation (AF). P-wave dispersion has been recognized as a sensitive tool for detecting interatrial conduction disturbances. Doppler myocardial imaging (DMI) has been validated as a non-invasive tool to indirectly reflect electrical atrial activation and therefore is used in this study to detect possible interatrial electromechanical disturbances after cardiac surgery. 30 patients (23 men, age 62 ± 1 years) admitted for coronary bypass surgery with no prior history of AF were included in this investigation. Echocardiography and electrocardiograms (ECG) were obtained on the day before and after surgery. In addition to standard echocardiography, DMI-loops were acquired from the apical window. The following time intervals were derived off-line from the free right atrial (RA), left atrial (LA) lateral and LA posterior wall: onset P-wave to start (P to Astart), to peak (P to Apeak)
TY - JOUR. T1 - Myocardial activation of the human cardiac α-actin promoter by helix- loop-helix proteins. AU - Sartorelli, V.. AU - Hong, N. A.. AU - Bishopric, N. H.. AU - Kedes, L.. PY - 1992/1/1. Y1 - 1992/1/1. N2 - The cardiac α-actin gene is expressed in both heart and skeletal muscle. In skeletal myogenic cells, the 177-base-pair promoter of the human cardiac α-actin (HCA) gene requires three transcription factors for activation: Sp1, serum response factor (SRF), and MyoD. However, MyoD is undetectable in heart. To search for a functional equivalent of MyoD, we analyzed the transcriptional regulation of the HCA promoter in primary cultures of rat cardiac myocytes. The same DNA sequence elements recognized by SRF, Sp1, and MyoD and required for HCA transcription in skeletal muscle cells were also found to be necessary for expression in cardiomyocytes. Overexpression of Id, a negative regulator of basic helix-loop-helix proteins, selectively attenuated expression of the HCA promoter. ...
The electrocardiograms of a 69-year-old woman with severe heart failure showed a left-sided nonspecific intraventricular conduction delay (QRS duration, 0.13 seconds) characterized by notches and slurrings in the descending part of the R waves in the
The methodologic limitations of low density in vivo mapping in humans, however, should not be underestimated. Though the observation of split potentials associated with an alteration of the activation sequence of the second component strongly suggests conduction block, a marked conduction delay cannot be excluded. Actually, conduction delays have been proved to be the cause of double potentials in different settings (i.e., intrahisian block). However, the alteration of the activation sequence of the second component gives further evidence of conduction block and findings from experimental studies with high density epicardial mapping support the interpretation of our observations (15,16,32).. Aside from that, conduction was determined during pacing in the lateral right atrium adjacent to the anterior edge of the CT in patients with documented atrial tachyarrhythmias. Pulse propagation in the opposite direction (from posterior to anterior) or in healthy subjects or after pacing apart from the ...
The classification of cardiac conduction disease has long been dominated by concepts anchored in macroscopic anatomical structures within the heart. The sinoatrial node, atrioventricular (AV) node and proximal His-Purkinje system can each be seen with the naked eye in humans, and in the most commonly used large animal models. Early physiologic data established the distinctive cellular electrical properties of these tissues and enshrined the fundamentals of physiologic and pathophysiologic conduction.1 Clinical cases where conduction disease was the predominant presenting feature were recognised as electrocardiography spread. Painstaking postmortem histomorphometric reconstructions of hearts from such cases resulted in the concepts of focal fibrosis, or a restricted degenerative process, as the mechanisms of isolated conduction disease.2. Parallel early work in surface electrocardiography and intracardiac recording documented the electrophysiologic correlates of proximal conduction-system ...
The preface of this text indicates that it would be of value as a guide for people starting to perform His bundle electrocardiography and also useful to those established in the field. Unfortunately, it has not reached these goals. Anatomical description has been stretched out over four chapters, but it lacks such pertinent details as the dimensions of the His bundle and bundle branches, and histology of the sinus node, A-V node, and accessory pathways. Chapter four on methodology for recording His bundle electrograms fails to mention the arm approach or the left heart techniques. The methodology used by the ...
Systole (when the heart squeezes) happens because the muscle cells of the heart gets smaller in size. When they get smaller we also say they contract. Electricity going through the heart makes the cells contract. The electricity starts in the sino-atrial node (acronym SA Node) The SA Node is a group of cells in the right atria. These cells start an electrical impulse. This electrical impulse sets the rate and timing at which all cardiac muscle cells contract. This motion is called atrial systole. Once electrical impulse goes through the atrio-ventricular node (AV Node). The AV Node makes the impulse slow down. Slowing down makes the electrical impulses get to the ventricles later. That is what makes the ventricular systole occur after atrial systole, and lets all the blood leave the atria before ventricle contracts (meaning squeeze). After the electrical impulse goes through the AV Node, the electrical impulse will go through the conduction system of the ventricle. Conduction means heat or ...
what does sinus arrhythmia non specific intraventricular conduction delay mean?what is its causes? This discussion is related to |a href=http://www.medhelp.org/posts/show/409489|abnormal ekg|/a|.
View Notes - Electrical Conduction Notes from MSE 2001 at Georgia Tech. Chapter 10 Notes Electrical Properties 1. Electrical Conduction a. Types of Charge Carriers i. Electrons ii. Holes (missing
In normal individuals, electrical activity in the heart is initiated in the sinoatrial (SA) node (located in the right atrium), propagates to the atrioventricular (AV) node, and then through the bundle of His to the ventricles of the heart. (See electrical conduction system of the heart).. The AV node acts as a gatekeeper, limiting the electrical activity that reaches the ventricles of the heart. This function of the AV node is important, because if the signals generated in the atria of the heart were to increase in rate (as they do during atrial fibrillation or atrial flutter), the AV node will limit the electrical activity that conducts to the ventricles. For instance, if the atria are electrically activated at 300 beats per minute, half those electrical impulses are blocked by the AV node, so that the ventricles are activated at 150 beats per minute (giving a pulse of 150 beats per minute). Another important property of the AV node is that it slows down individual electrical impulses. This is ...
Properties of the cardiac muscle AUTOMATICITY CONDUCTIVITY CONTRACTILITY EXCITABILITY REFRACTORY PERIODS 1. AUTOMATICITY is the unique ability of the cells in the SA node (pacemaker cells) to generate an action potential without being stimulated.
Primary cardiac neoplasms (PCNs) represent the rarest form of neoplastic growths worldwide with an incidence ranging from 0.001 - 0.3% in autopsy series (Yu et al., 2014) (Primary Cardiac Neoplasms, 2014). The rarity of these tumors has contributed to the challenges associated with their diagnosis and treatment (Primary Cardiac Neoplasms, 2014). Primary heart tumors are generally classified as benign or malignant based on whether or not the tumors cells invade their surrounding tissue. Primary benign heart tumors can be further sub-classified as non-complicated or complicated. Non-complicated tumors are those that are stable, occur alone, and do not invade the cardiac conduction system. Conversely, complicated primary benign cardiac neoplasms are those that tend to break off into systemic circulation increasing the risk for embolization, have multicentered origins within the heart and/ or invade the cardiac conduction system which may lead to heart block and sudden death (Cardiac Tumors: ...
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To determine the effect of cardiac conduction defects on the signal-averaged electrocardiogram (ECG) and on its ability to noninvasively identify patients predisposed to ventricular tachycardia (VT), standard 12-lead ECGs and signal-averaged ECGs wer
TY - GEN. T1 - Time response of electrical conduction block in novel cardiomyocyte wire by extra-cellular photosensitization reaction at various irradiances. AU - Kurotsu, Mariko. AU - Ogawa, Emiyu. AU - Arai, Tsunenori. PY - 2014/1/1. Y1 - 2014/1/1. N2 - We studied time response of electrical conduction (EC) block in a novel cardiomyocyte wire by extra-cellular photosensitization reaction (EPR) at various irradiances. This EC block using the EPR has been studied to develop a non-thermal arrhythmia therapeutic methodology. Despite the EC block in acute phase is needed to judge therapeutic endpoint in clinical arrhythmia therapy, time response of the EC block by the EPR in acute phase hasn’t been studied. We measured the time to EC block occurrence by the EPR with intra-cellular Ca2+ concentration change using Fluo-4 AM fluorescence measurement by a confocal laser microscope system. The pattern cultivation cover glass with 10 mm Φ which had 60 μm width cultivation areas with 300 μm ...
Left Anterior Fascicular Block (LAFB) is a condition that affects the hearts conduction system, which is responsible for generating electrical impulses (waves) that propagate throughout the musculature of the heart, stimulating the heart muscles to contract and pump blood. If the conduction system is disrupted, not only will contraction of the heart muscles be affected, but the timing and frequency of heartbeats too.
Cardiac tissue engineering has a potential to provide functional, synchronously contractile tissue constructs for heart repair, and for studies of development and disease using in vivo-like yet controllable in vitro settings. In both cases, the utilization of bioreactors capable of providing biomimetic culture environments is instrumental for supporting cell differentiation and functional assembly. In the present study, neonatal rat heart cells were cultured on highly porous collagen scaffolds in bioreactors with electrical field stimulation. A hallmark of excitable tissues such as myocardium is the ability to propagate electrical impulses. We utilized the method of optical mapping to measure the electrical impulse propagation. The average conduction velocity recorded for the stimulated constructs (14.4 +/- 4.1 cm/s) was significantly higher than that of the nonstimulated constructs (8.6 +/- 2.3 cm/s, p = 0.003). The measured electrical propagation properties correlated to the contractile behavior and
A DNA nonbinding mutant of the NK2 class homeoprotein Nkx2.5 dominantly inhibits cardiogenesis in Xenopus embryos, causing a small heart to develop or blocking heart formation entirely. Recently, ten heterozygous CSX/NKX2.5 homeoprotein mutations were identified in patients with congenital atrioventricular (AV) conduction defects. All four missense mutations identified in the human homeodomain led to markedly reduced DNA binding. To examine the effect of a DNA binding-impaired mutant of mouse Csx/Nkx2.5 in the embryonic heart, we generated transgenic mice expressing one such allele, I183P, under the β-myosin heavy chain promoter. Unexpectedly, transgenic mice were born apparently normal, but the accumulation of Csx/Nkx2.5(I183P) mutant protein in the embryo, neonate, and adult myocardium resulted in progressive and profound cardiac conduction defects and heart failure. P-R prolongation observed at 2 weeks of age rapidly progressed into complete AV block as early as 4 weeks of age. Expression of ...
TY - JOUR. T1 - Mechanistic insight into spontaneous transition from cellular alternans to arrhythmia-A simulation study. AU - Wang, Wei. AU - Zhang, Shanzhuo. AU - Ni, Haibo. AU - Garratt, Clifford J. AU - Boyett, Mark R. AU - Hancox, Jules C. AU - Zhang, Henggui. PY - 2018/11/30. Y1 - 2018/11/30. N2 - Cardiac electrical alternans (CEA), manifested as T-wave alternans in ECG, is a clinical biomarker for predicting cardiac arrhythmias and sudden death. However, the mechanism underlying the spontaneous transition from CEA to arrhythmias remains incompletely elucidated. In this study, multiscale rabbit ventricular models were used to study the transition and a potential role of INa in perpetuating such a transition. It was shown CEA evolved into either concordant or discordant action potential (AP) conduction alternans in a homogeneous one-dimensional tissue model, depending on tissue AP duration and conduction velocity (CV) restitution properties. Discordant alternans was able to cause conduction ...
Besides enhanced automaticity, ischemia also provides the substrate for reentry by increasing dispersion of excitability, reducing conduction velocities, and shortening refractory periods in ischemic areas (Coronel, 1994). Occlusion of the LAD resulted in a significant increase in Q-J time. The Q-J time reflects ventricular activation, the time needed for the electrical impulse to travel through the fast-conducting His-Purkinje system to the cardiomyocytes, and to activate the majority of these cells so that their action potential is in phase 2. Regional ischemic injury within the myocardium disturbs intraventricular conduction (Gettes and Cascio, 1992), in both space and time, leading to an altered spectrum of the QRS complex (Hatala et al., 1995) and an increase in Q-J time. The latter is mainly due to the slower or even blocked impulse conduction in the ischemic region. An altered spectrum of the QRS complex and an increase in the Q-J time have been demonstrated in the ischemic control group ...
Bundle branches are clusters of pathways that carry electrical impulses to different parts of your heart. A bundle branch block is a delay or obstruction in one of the pathways. These can keep your heart from pumping normally. Many blocks are caused by heart disease, some are there at birth. If the condition is serious, a pacemaker may be prescribed.   The key bundle is the bundle of His, the him in question being the discoverer, Wilhelm His, Jr. This bundle distributes the electrical impulse from the AV node to each ventricle, where it branches into the left and right bundle branches.
Background: The post-infarct ventricular tachycardia (VT) substrate is characterized by structural and electrical heterogeneities. Repolarization heterogeneity contributes to VT arrhythmogenesis but the impact of repolarization gradients on post-infarct VT dynamics is not well-characterized. Objective: The goal of this study is to assess the effects of repolarization gradients on post-infarct VT dynamics using patient-specific heart models. Methods: 3D late gadolinium-enhanced magnetic resonance images were acquired from 7 patients with ischemic heart disease. Baseline models were reconstructed along with the patient-specific scar and infarct border zone distributions. Models with physiological action potential duration (APD) gradients along apicobasal (AB) and transmural (TM) axes were reconstructed. Rapid pacing from the right ventricular apex was applied to induce VTs. For models with APD gradients, two pacing protocols were applied: (1) exact timed stimulus that matched the timing of ...
Functional reentry has been hypothesized to be an underlying mechanism of ventricular fibrillation (VF); however, its contribution to activation patterns during fully developed VF is unclear. We applied new quantitative pattern analysis techniques to mapping data acquired from a 21 x 24 unipolar electrode array (2-mm spacing) located on the ventricular epicardium of 7 open-chest, unsupported pigs. Data epochs 4 seconds long beginning 1, 10, 20, 30, and 40 seconds after electrical induction were analyzed. Reentrant circuits were automatically identified and quantified. We found that 2.3% of activation pathways could unambiguously be classified as reentrant. From scaling analysis, an additional 28% of the pathways may also have been reentrant. Reentry was short-lived with 1.5 ± 1.5 (mean ± SD) complete cycles per circuit. The fraction of reentrant pathways, number of cycles per circuit, cycle duration, and area and perimeter of the cores all increased significantly as VF progressed. Core drift ...
This is a randomized, partially-blinded, placebo and moxifloxacin-controlled, single dose, 4-period, balanced crossover study. The primary objective of this study is to separately assess the effects of a therapeutic and supratherapeutic dose of GSK1322322 on the cardiac conduction (corrected QT interval [QTc]) compared with placebo in eligible healthy male and female subjects. Avelox (moxifloxacin hydrochloride) will be used as an open-label positive control in order to validate the sensitivity of the study in detecting QTc change. Approximately 56 healthy subjects will participate in the study for approximately 9 weeks i.e. 30 day Screening period, 4-week Treatment period, and a 7-10 day Follow-up period. There will be 4 treatment periods separated by at least 1 week. Subjects will be admitted to the clinical unit on Day -1 of each dosing period. Each subject will receive each of the four treatment sequences (GSK1322322 1200 milligram [mg] intravenous [IV] over 60 minutes x 1 dose, GSK1322322 ...
An electrophysiological study (EP study) is an invasive procedure that tests the hearts electrical system. The electrical system of the heart generates the heart beat.. During an EP study, a small, plastic catheter (tube) is inserted through a vein in the groin (or neck, in some cases) and is threaded into the heart, using a special type of X-ray, called fluoroscopy, to guide the catheter. Once in the heart, electrical signals are sent through the catheter to the heart tissue to evaluate the electrical conduction system contained within the heart muscle tissue.. There are several ways in which EP studies may be performed to assist in diagnosing electrical conduction system abnormalities of the heart. For example, a dysrhythmia/arrhythmia (an abnormal rhythm) may be deliberately stimulated by a doctor during the EP study so that the underlying abnormal electrical circuitry can be identified. Likewise, in order to evaluate the effectiveness of an antiarrythmic medication, an attempt may be made ...
The NK2 class homeoprotein Csx/Nkx2.5 is among the earliest cardiogenic markers from fly to vertebrate (1-9). In this study, we generated transgenic mice expressing a putative dominant inhibitory mutant of Csx/Nkx2.5 (13, 14) under the β-MHC promoter in order to examine Csx/Nkx2.5 function in the mammalian embryonic heart. Overexpression of a DNA-nonbinding mutant of XNkx2.5 in Xenopus embryos resulted in small hearts or a complete loss of heart (13). We anticipated similar results in mice, but that was not the case. The accumulation of Csx/Nkx2.5(I183P) mutant protein in the embryo, neonate, and adult myocardium resulted in progressive and profound cardiac conduction defects and heart failure.. One possible explanation for the phenotypic difference observed in the Xenopus system and in our transgenic mice is the different experimental conditions in the different species. In Xenopus, the mutant mRNA was injected in dorsal-vegetal blastomeres of the eight-cell stage (2.25 hours after ...
At Dawns request, this months ECG is laying down the foundation for a topic she wanted me to eventually talk about on the ECG Guru. On this ECG, Im not just looking for the obvious disturbance of rhythm. This type of ECG is literally begging for a laddergram to help reveal the mechanism responsible for a couple of very subtle and rare findings ...
Resting electrocardiogram (ECG) - a test used to check heart rhythm and electrical activity. This simple investigation helps to diagnose cardiovascular system diseases. The electrocardiogram shows various cardiac arrhythmias, cardiac conduction system injury, ischemic heart muscle changes (previous myocardial infarction ...
Measuring the electrical conductivity through a specific strand of DNA is of great interest to the nano-science and engineering community. This work focuses on the electrical conduction through 15 base-pair, double helix oligo-nucleotides with various sequences. The current-voltage characteristics of the double strands are measured in a metal(Au)/ds-DNA/metal(Au) structure fabricated by immobilizing the dithiol derivatized double-stranded DNA oligionuleotide sequences in nanoscale gaps between pairs of gold (Au) electrodes, achieved through an electromigration-induced break-junction (EIBJ) technique performed at room temperature.
The present invention enables hemodynamic efficiencies for patients suffering from intraventricular conduction delays or conduction blockage. The invention effectively overcomes such conduction delay or block (e.g., left bundle branch block,
abstract = Connexin 43 (Cx43), a gap junction protein seemingly fit to support cardiac impulse propagation and synchronic contraction, is phosphorylated in normoxia by casein kinase 1 (CK1). However, during cardiac ischemia or pressure overload hypertrophy, this phosphorylation fades, Cx43 abundance decreases at intercalated disks and increases at myocytes lateral borders, and the risk of arrhythmia rises. Studies in wild-type and transgenic mice indicate that enhanced CK1-phosphorylation of Cx43 protects from arrhythmia, while dephosphorylation precedes arrhythmia vulnerability. The mechanistic bases of these Cx43 (de)phosphoform-linked cardiac phenotypes are unknown. We used patch-clamp and dye injection techniques to study the channel function (gating, permeability) of Cx43 mutants wherein CK1-targeted serines were replaced by aspartate (Cx43-CK1-D) or alanine (Cx43-CK1-A) to emulate phosphorylation and dephosphorylation, respectively. Cx43-CK1-D, but not Cx43-CK1-A, displayed high ...