An example of bilateral bundle-branch block (RBBB) in the presence of WPW syndrome in which diagnosis was established with the aid of His bundle recordings is presented. Complete RBBB and intermittent block of the superior and inferior divisions of the left bundle branch were coexistent for at least 2 years before complete heart block (trifascicular block) occurred. It was demonstrated that the preexcitation pathway conducted and blocked together with the normal pathways. It is suggested that the anomalous bundle in this case traveled with the normal pathways and that this close relationship is more common than has been suspected.. Retrograde V-A conduction at 1:1 ratio was present during electrical stimulation of the right ventricle and the anomalous bundle was used for retrograde spread of activation from the ventricles to the atria. The retrograde P waves, thus produced, conducted antegrade through the His bundle (reciprocation) but reached the ventricles only when they appeared near the end ...
TY - JOUR. T1 - Low-energy transvenous ablation of the canine atrioventricular conduction system with a suction electrode catheter. AU - Saksena, S.. AU - Tarjan, P. P.. AU - Bharati, S.. AU - Boveja, B.. AU - Cohen, D.. AU - Joubert, T.. AU - Lev, M.. N1 - Copyright: Copyright 2017 Elsevier B.V., All rights reserved.. PY - 1987. Y1 - 1987. N2 - A single suction electrode catheter was used for His bundle electrogram recording, His bundle pacing, and low-energy (20 or 30 J) His bundle ablation in seven dogs. The suction electrode catheter was actively fixed to the atrial endocardium at the His bundle level. Electrophysologic studies were performed in the control state, immediately after, and late (, 40 days) after His bundle ablation and results were correlated with histologic findings in the conduction system. Unipolar His bundle recording and pacing were successfully performed in all dogs with the suction electrode catheter before and after ablation. Complete heart block developed after a ...
His bundle electrograms were recorded in three patients with short P-R intervals, narrow QRS complexes, and a history of paroxysmal tachycardias. During sinus rhythm or atrial stimulation with long cycle lengths, the shortening of the P-R interval was due to a decrease in the low right atrium-His (LRA-H) interval (representing A-H conduction time). The latter was also short during retrograde (V-A) conduction. These findings support the existence of an A-V nodal bypass operation in both directions. In one patient, the LRA-H interval did not lengthen when the atrial rate was increased. Intermittent atrial pacing was performed in the two other patients. The LRA-H interval was short at long coupling intervals, but it started to increase (progressively) at a given Stimulus1-Stimulus2 interval. Apparently, the refractory period of the accessory bundle was encountered so that the impulse was propagated, with various degrees of delay, through the A-V node. A James bundle need not be present in all ...
Under normal physiologic conditions, the dominant pacemaker cells of the heart lie within the sinoatrial node; in adults, these pacemaker cells fire at rates between 60 to 100 beats per minute (i.e., faster than cells in any other cardiac region, See Figure 3). Even at rest, modulation by the autonomic nervous system dominates, with the primary drive from the parasympathetics; at rest or during sleep, the sinoatrial nodal rate decreases to about 75 beats per minute (bpm) or even slower.. In addition to pacemaker cells of the sinoatrial node, other cells within the conduction system are capable of developing autorhythmicity, specifically those within the atrioventricular node (junction region) and His-Purkinje system. Yet, rhythms generated within these cells are in a much lower range (25 to 55 bpm), hence not altering the intrinsic atrial rates (Figure 2). These lower rate rhythms are commonly referred to as ventricular escape rhythms and are important for patient survival, since they maintain ...
Several features remained to be clarified concerning the developmental origin of the atrioventricular conduction axis. For example, is the embryonic atrioventricular canal the major source of the atrial part of the conduction axis,10,11,13 or are major contributions made by adjacent tissues, such as the atrial chamber myocardium, the left sinus horn, the dorsal mesenchymal protrusion, or the atrioventricular bundle?15,17,-,20 What are the lineage origins of the atrial and ventricular parts of the axis, respectively?19,20 By our use of genetic lineage tracing, we have excluded the notion that contributions to the atrial part of the axis are made from the sinus horns or the epicardium (Tbx18+), from the ventricular myocardium, including the atrioventricular bundle, or from the dorsal mesenchymal protrusion (Mef2c-AHF-Cre+). The majority of the atrial components is derived from the embryonic atrioventricular canal, except for the lower nodal cells, which are derived from the embryonic ventricular ...
A form of ventricular pre-excitation characterized by a short PR interval and a normal QRS complex. In this syndrome, the atrial impulse conducts via the JAMES FIBERS which connect the atrium to BUNDLE OF HIS bypassing the upper ATRIOVENTRICULAR NODE. HEART VENTRICLES are depolarized normally through the His-Purkinje system ...
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 ...
Out-of-hospital cardiac arrest treated by emergency medical services has an estimated incidence of 54.99 per 100,000 person years, which translates to some 155,000 episodes annually in the United States. Bradyasystole is the first recorded rhythm in up to 52 percent of cardiac arrests, and many additional patients with an initial cardiac arrest rhythm of ventricular fibrillation deteriorate to bradyasystole after defibrillation efforts. Survival to hospital discharge occurs in less than 3 percent of patients presenting with bradyasystole; however, due to its frequency, this rhythm accounts for over 17 percent of all cardiac arrest survivors. As a result, even a small improvement in survival from bradyasystolic cardiac arrest would result in thousands of lives saved annually.. Adenosine is an endogenous purine nucleoside that depresses the sinoatrial node, blocks atrioventricular conduction, inhibits the pacemaker activity of the His-Purkinje system and attenuates the effects of catecholamines. ...
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
Eleven patients with an accessory pathway and reciprocating tachycardia were studied using both fixed rate atrial pacing and the atrial extrastimulus technique. Six of the patients had an accessory pathway that conducted in both the anterograde and r
The purpose of this study is to explore if there is a less harmful way to pace patients with first-degree AV-block to ensure that the negative effects inferred by the pacing do not outweigh the positive effects of AV-synchrony. The main hypothesis of the study is that His-bundle pacing will offer a more physiological mode of pacing in patients with first-degree AV-block than conventional pacing.. Patients scheduled for catheter ablation of atrial fibrillation (AF) in sinus rhythm, with first degree AV-block, normal QRS duration less than 120 ms and normal left ventricular ejection fraction will be included. During the AF ablation three different pacing modes (atrial, AV-synchronous and His-bundle pacing) at two different rates (5 to10 bpm above the basal rate and at 100 bpm) will be performed and evaluated using echocardiography. After the completion of all six pacing protocols (i.e., three modes at two different rates) the experimental part of the procedure ends.. The primary end-point will be ...
Definisi Hambatan Atrioventrikuler (Atrioventricular block) adalah kelainan pada sistem koduksi jantung dimana depolarisasi atrium gagal untuk mencapai ventrikel atau depoilarisasi atrial yang terkonduksikan dengan terlambat. Hambatan Atrioventrikuler (Blok AV) kerap menjadi penyebab bradikardia meskipun lebih jarang dibandingkan dengan kelainan fungsi nodus SA yang juga menyebabkan gejala bradikardia. 2.2. Klasifikasi Berdasarkan derajat hambatan, gangguan ini dibagi menjadi blok AV derajat 1, blok AV derajat 2, dan blok AV derajat 3 ( total ). Blok AV Derajat 1 terjadi bila semua impuls dari atrium dapat dihantarkan ke ventrikel dengan waktu hantaran yang lebih lama ( pada EKG interval PR, 0,20 detik ). Kelainannya biasanya pada tingkat nodus AV dan jarang pada sistem His-Purkinje. Karena semua impuls dari atrium dapat dihantarkan ke ventrikel maka biasanya tidak menimbulkan gejala. Blok AV Derajat 2 terjadi pada keadaan dimana tidak semua impuls dari atrium dapat dihantarkan melalui nodus AV ...
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Right bundle branch block Differential diagnosis of right bundle branch block / causes of right bundle branch block are : -pulmonary embolism
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 ...
Left bundle branch blocks. In left bundle branch block (LBBB) the left ventricle is not directly activated by impulses travelling through the left bundle branch. The right ventricle, however, is still activated as normal by the right bundle branch.. The left ventricle is activated by impulses travelling through the myocardium across the septum. As this occurs more slowly than conduction through the bundle of His the QRS complex becomes widened.. Normally the septum is activated from left to right, which produces small Q waves in the lateral leads. In the presence of LBBB, however, this septal activation is reversed, which eliminates these normal septal Q waves.. The right to left depolarization of the myocardium produces deep S waves in the right praecordial leads (V1-V3) and tall R waves in the lateral leads (I, V5 and V6). It also usually causes left axis deviation. As the ventricles are activated sequentially from right to left, rather than simultaneously, the R wave in the lateral leads is ...
SCN5A_HUMAN] Defects in SCN5A are a cause of progressive familial heart block type 1A (PFHB1A) [MIM:113900]; also known as Lenegre-Lev disease or progressive cardiac conduction defect (PCCD). PFHB1A is an autosomal dominant cardiac bundle branch disorder that may progress to complete heart block. PFHB1A is characterized by progressive alteration of cardiac conduction through the His-Purkinje system with right or left bundle branch block and widening of QRS complexes, leading to complete atrioventricular block and causing syncope and sudden death.[1] [2] [3] [4] [5] [6] Defects in SCN5A are the cause of long QT syndrome type 3 (LQT3) [MIM:603830]. Long QT syndromes are heart disorders characterized by a prolonged QT interval on the ECG and polymorphic ventricular arrhythmias. They cause syncope and sudden death in response to exercise or emotional stress. LQT3 inheritance is an autosomal dominant.[7] [8] [9] [10] [11] [12] [13] [14] [:][15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] ...
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 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 ...
Learn about right bundle branch block, an abnormal finding on the electrocardiogram that is often associated with underlying heart disease.
The most common causes of a right bundle branch block are a previous heart attack, a congenital deformity, cardiovascular disease...
Right bundle branch block treatment is not always necessary but it can be essential to ensure the condition doesnt exacerbate. Complication and prevention is also available.
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...
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] ...
Definition of bundle branch block, complete in the Legal Dictionary - by Free online English dictionary and encyclopedia. What is bundle branch block, complete? Meaning of bundle branch block, complete as a legal term. What does bundle branch block, complete mean in law?
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
Importance of Retrograde Atrial Activation in Atrial Fibrillation Genesis in the Initiation of Atrial Fibrillation in Wolff-Parkinson-White Syndrome. Comparison of Atrial Electrophysiologic Parameters between Patients with Different Atrial Fibrillation Genesis (Initiation Sites) in Atria. (1999 ...
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 ...
Dr. Stern responded: None necessary. No treatment necessary and it is not serious unless other |a href=/topics/heart track_data={
How do the interpretation rules for ST segment proportionality, concordance and discordance apply to right bundle branch block in patients with chest pain ...
There are a lot of things I miss about being pregnant but there are a select few that really stick out and feel ever-present as this year comes to a close. The consistent intense feeling of grief fades a bit over time but the shorter, intermittent bursts of sadness are hella powerful even 6 months…
MalaCards based summary : Right Bundle Branch Block, also known as right bundle branch block with left posterior fascicular block, is related to heart block, progressive, type ia and rheumatic heart disease. An important gene associated with Right Bundle Branch Block is SCN5A (Sodium Voltage-Gated Channel Alpha Subunit 5), and among its related pathways/superpathways are Activation of cAMP-Dependent PKA and Developmental Biology. The drugs Tolvaptan and Arginine Vasopressin have been mentioned in the context of this disorder. Affiliated tissues include heart, testes and spinal cord, and related phenotype is cardiovascular system ...
TY - JOUR. T1 - Effects of the pacing site in sinus node reentrant tachycardia. AU - Castellanos, Agustin. AU - Aranda, Juan. AU - Moleiro, Federico. AU - Mallon, Stephen M.. AU - Befeler, Benjamin. PY - 1976. Y1 - 1976. N2 - His bundle recordings and premature atrial stimulation from coronary sinus, mid-right atrium and high-right atrium were performed in a patient with repetitive supraventricular tachycardias. Regardless of the paced site, there was a range of coupling intervals during which testing stimuli elicited short runs of premature beats. The corresponding P waves were positive in leads I, II and II and had a high-to-low right atrial activation sequence. Their morphology was similar to that of sinus beats. However, sustained tachycardia occurred only when pacing was performed from the coronary sinus. Therefore, it is postulated that the site of stimulation might be important in the genesis and (perhaps) perpetuation of this arrhythmia by changing the site and (or) mode of entry into ...
TY - JOUR. T1 - Clinical and genetic heterogeneity of right bundle branch block and ST-segment elevation syndrome. T2 - A prospective evaluation of 52 families. AU - Priori, Silvia G.. AU - Napolitano, Carlo. AU - Gasparini, Maurizio. AU - Pappone, Carlo. AU - Della Bella, Paolo. AU - Brignole, Michele. AU - Giordano, Umberto. AU - Giovannini, Tiziana. AU - Menozzi, Carlo. AU - Bloise, Raffaella. AU - Crotti, Lia. AU - Terreni, Liana. AU - Schwartz, Peter J.. PY - 2000/11/14. Y1 - 2000/11/14. N2 - Background - The ECG pattern of right bundle branch block and ST-segment elevation in leads V1 to V3 (Brugada syndrome) is associated with high risk of sudden death in patients with a normal heart. Current management and prognosis are based on a single study suggesting a high mortality risk within 3 years for symptomatic and asymptomatic patients alike. As a consequence, aggressive management (implantable cardioverter defibrillator) is recommended for both groups. Methods and Results - Sixty patients ...
The aim of this study was to perform a pilot histological and quantitative analysis of the blood vessels accompanying the epicardial nerves (vasa nervorum) in the porcine hearts. Twenty healthy porcine hearts were used in this study. The blood vessels were analyzed by light microscopy using four different staining techniques in transverse sections taken from the upper, middle, and lower segments of the anterior part of the interventricular region and the adjacent parts of the right and left ventricles containing epicardial nerves and the endocardial peripheral parts of the Purkinje fibers. In total, 317 epicardial nerves were detected. The vasa nervorum were present in 75.7% of these nerves. The vasa nervorum resembled arterioles and postcapillary and collecting venules. One hundred and forty nine epicardial nerves were perivascular, located in the adventitia of the anterior interventricular artery and vein. The remaining 168 nerves ran freely through the epicardial interstitium. The presence of ...
LGL syndrome is diagnosed in a person who has experienced episodes of abnormal heart racing (arrhythmias) who has a PR interval less than or equal to 0.12 second (120 ms) with normal QRS complex configuration and duration on their resting ECG.[1] A short PR interval found incidentally on an ECG without episodes of tachycardia is simply a benign ECG variant. LGL can be distinguished from WPW syndrome because the delta waves seen in WPW syndrome are not seen in LGL syndrome. The QRS complex will also be narrow in LGL syndrome, as opposed to WPW, because ventricular conduction is via the His-Purkinje system. Lown-Ganong-Levine syndrome is a clinical diagnosis that came about before the advent of electrophysiology studies. It is important to be aware that not all WPW ECGs have a delta wave; the absence of a delta wave does not conclusively rule out WPW. ...
FLEC : Flecainide (Tambocor) is a class I cardiac antiarrhythmic agent with electrophysiologic properties similar to lidocaine, quinidine, procainamide, and tocainide. Flecainide produces a dose-related decrease in intracardiac conduction in all parts of the heart, with the greatest effect on the His-Purkinje system. Atrial effects are limited. Flecainide causes a dose-related and plasma concentration-related decrease in single and multiple premature ventricular contractions and can suppress recurrence of ventricular tachycardia.   Flecainide is eliminated from blood by hepatic metabolism as well as renal clearance; significant changes in either organ system will cause impaired clearance. During preclinical trials, patients with congestive heart failure were observed to have radically altered clearance properties. Cardiac toxicity attributed to flecainide is related to its cardiac conduction slowing properties. Excessive prolongation of PR, QRS, and QT intervals occurs with increased amplitude
Arrhythmias that originate in the ventricular myocardium or His-Purkinje system include premature ventricular beats, ventricular tachycardias that can be sustained or nonsustained, and ventricular fibrillation. Arrhythmia may emerge from a focus of myocardial or Purkinje cells capable of automaticity, or triggered automaticity, or from reentry through areas of scar or a diseased Purkinje system. Ventricular arrhythmias are often associated with structural heart disease and are an important cause of sudden death (Chap. 327). They also occur in some structurally normal hearts, in which case they are usually benign. Evaluation and management are guided by the risk of arrhythmic death, which is assessed based on symptoms, type of arrhythmia, and associated underlying heart disease. ...
We report the case of a 56-year-old male with ischemic cardiomyopathy, severe left ventricular dysfunction and right bundle branch block (RBBB) with a wide QRS duration (180ms) who received dual-chamber implantable cardioverter-defibrillator for prim
Question - Is right bundle branch block related to kidney problem?. Ask a Doctor about diagnosis, treatment and medication for Arrhythmogenic right ventricular dysplasia, Ask a Cardiac Surgeon
Dear Doctor, I have been diagnost with an incomplete right bundle branch block. I am 45 and 108 punds. All physical, stress test and blood work is fine. The doctor tells me not to worry. However ...
Karel Frederik Wenckebach (March 24, 1864 - November 11, 1940) was a Dutch anatomist who was a native of the Hague. He studied medicine in Utrecht, and in 1901 become a professor of medicine at the University of Groningen. Later he was a professor at the Universities of Strasbourg (1911-14) and Vienna (1914-29). Wenckebach (pronounced ven-kĕ-bak) is primarily remembered for his work in cardiology. In 1899 he provided a description of irregular pulses due to partial blockage of atrioventricular conduction, creating a progressive lengthening of conduction time in cardiac tissue. The condition was referred to as a second degree AV block and later named the Wenckebach phenomenon and reclassified as Mobitz type I block in Mobitzs 1924 paper. A similar phenomenon can also occur in the Sinoatrial node where it gives rise to Type I second degree SA block, and this is also known as a Wenckebach block; the two have distinct features on an ECG however. Wenckebach is credited for describing the ...
Cardiac conduction in the adult heart begins in the sinoatrial (SA) node, which is located at the junction between the SVC and the right atrium. The impulses generated here spread through the atria, initiating contraction. The impulses travel to the atrioventricular (AV) node which acts to slow the transmission of an impulse between the atria and ventricles. After this time lag, impulses travel to the ventricles via the common atrioventricular bundle (bundle of His) to the bundle branches in the IV septum. The branches split and terminate throughout the myocardium in a network of Purkinje fibres. The adult conduction system is shown below ...
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.
This ECG was obtained from an 84-year-old woman who was scheduled for surgery. When the anesthesiologist did this ECG, the surgery was cancelled. It is a very good example of fascicular-level blocks. The underlying rhythm is a regular sinus rhythm at about 95 bpm. There are some non-conducted P waves which are part of the sinus rhythm (not premature beats). When the P waves DO conduct, the PR interval is steady at about .15 seconds (148 ms).. In addition, there is a LEFT BUNDLE BRANCH BLOCK. The ECG criteria for LBBB are: 1) A supraventricular rhythm, 2) A wide QRS, and 3) A negative QRS in Lead V1 and a positive QRS in Leads I and V6. The QRS duration in this ECG is 136 ms.. There are generally two fascicles (branches) in the left bundle branch, and one main fascicle in the right bundle branch. So, a LBBB represents a bi-fascicular block. That means that A-V conduction is proceeding down only one fascicle (the right bundle branch). In that fascicle, there is an intermittent block. When the ...
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.
The term cardiac preexcitation was originally used to describe premature activation of the ventricles in patients with the Wolff-Parkinson-White (WPW) pattern. This term has been broadened to include all conditions in which antegrade ventricular acti
Aphids ingest their food from sieve tubes (Auclair, 1963; Miles, 1987; Prado and Tjallingii, 1994) that contain a concentrate of nutrients (Hayashi and Chino, 1990; van Bel, 2003). Sieve-tube sap is withdrawn by specialized aphid mouth parts (stylets) (Auclair, 1963; Miyazaki, 1987). Prior to ingestion, aphids secrete watery saliva, probably to interfere with plant occlusion reactions induced by stylet damage (Will and van Bel, 2006; Will et al., 2007; Will et al., 2009; Carolan et al., 2009).. Transmission electron microscopy (TEM) reconstructions demonstrate relatively straightforward stylet progression through the extravascular tissue that occurs largely intercellularly. The stylet orientation becomes increasingly diffuse within the vascular bundle region, as the TEM reconstructions show several dead-end tracks of gel saliva, which is secreted to function as a lubrication and protection sheath for the fragile mouth parts (Tjallingii and Hogen Esch, 1993). Even punctured sieve tubes are ...
Aims We investigated the applicability of the Ventricular Capture Control (VCC) and Atrial Capture Control (ACC) algorithms for automatic management of cardiac stimulation featured by Biotronik pacemakers in a broad, unselected population of pacemaker recipients. Methods and results Ventricular Capture Control and Atrial Capture Control were programmed to work at a maximum adapted output voltage as 4.8 V in consecutive recipients of Biotronik pacemakers. Ambulatory threshold measurements were made 1 and 12 months after pacemaker implant/replacement in all possible pacing/sensing configurations, and were compared with manual measurements. Among 542 patients aged 80 (73-85) years, 382 had a pacemaker implant and 160 a pacemaker replacement. Ventricular Capture Control could work at long term in 97% of patients irrespectively of pacing indication, lead type, and lead service life, performance being superior with discordant pacing/sensing configurations. Atrial Capture Control could work in 93% of ...
Junctional rhythm is an abnormal heart rhythm in the atrioventricular node. Though its not always dangerous, it can be a sign of...
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I have RBBB, and occasional PVCs, sometimes during exercise. Should answer 1 say or you have PVCs with right bundle branch block morphology on EKG?? Could you tell me, are there PVCs with a left and right bbb morphology (and which is visible on the EKG?) The first answer scared me a little bit, to be honest.. Sometimes I have a tachycardia which I cannot explain. It starts with me feeling my heart beating in my throat. It feels like my heart has suddenly shifted 20 cm upwards in my chest and I can feel it beat high in my chest / throat. One time this happened before going to the gym. It started to accelerate to about 160 bpm, then I tried to relax and it went back to about 100 bpm. I refused to give in to anxiety, so I started to work out anyway. However, as soon as I started lifting weights (and thus my heartrate would go up) I would immediately feel it back in my throat. It was so annoying (and still scary) that I gave up working out after 10 mins, because it didnt feel good ...
This information is intended for physicians and related personnel, who understand that medical information is often imperfect, and must be interpreted in the context of a patients clinical data using reasonable medical judgment. This website should not be used as a substitute for the advice of a licensed physician ...
DENVER/November 30, 2018 - Morris Animal Foundation-funded researchers have developed a new treatment for dogs with a rare, but life-threatening, arrhythmia caused by atrioventricular accessory ...
Is there a P Wave before each QRS? Are P waves upright and uniform? occur before, during or after the QRS depending on where the pacemaker is located in the AV junction.; P wave may be inverted ...
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