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Kenneth A Ellenbogen - One of the best experts on this subject based on the ideXlab platform.
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benefits of permanent his bundle pacing combined with Atrioventricular Node ablation in atrial fibrillation patients with heart failure with both preserved and reduced left ventricular ejection fraction
Journal of the American Heart Association, 2017Co-Authors: Weijian Huang, Lan Su, Shengjie Wu, Lei Xu, Fangyi Xiao, Xiaohong Zhou, Kenneth A EllenbogenAbstract:Background Clinical benefits from His bundle pacing (HBP) in heart failure patients with preserved and reduced left ventricular ejection fraction are still inconclusive. This study evaluated clinical outcomes of permanent HBP in atrial fibrillation patients with narrow QRS who underwent Atrioventricular Node ablation for heart failure symptoms despite rate control by medication. Methods and Results The study enrolled 52 consecutive heart failure patients who underwent attempted Atrioventricular Node ablation and HBP for symptomatic atrial fibrillation. Echocardiographic left ventricular ejection fraction and left ventricular end‐diastolic dimension, New York Heart Association classification and use of diuretics for heart failure were assessed during follow‐up visits after permanent HBP. Of 52 patients, 42 patients (80.8%) received permanent HBP and Atrioventricular Node ablation with a median 20‐month follow‐up. There was no significant change between native and paced QRS duration (107.1±25.8 versus 105.3±23.9 milliseconds, P =0.07). Left ventricular end‐diastolic dimension decreased from the baseline ( P <0.001), and left ventricular ejection fraction increased from baseline ( P <0.001) in patients with a greater improvement in heart failure with reduced ejection fraction patients (N=20) than in heart failure with preserved ejection fraction patients (N=22). New York Heart Association classification improved from a baseline 2.9±0.6 to 1.4±0.4 after HBP in heart failure with reduced ejection fraction patients and from a baseline 2.7±0.6 to 1.4±0.5 after HBP in heart failure with preserved ejection fraction patients. After 1 year of HBP, the numbers of patients who used diuretics for heart failure decreased significantly ( P <0.001) when compared to the baseline diuretics use. Conclusions Permanent HBP post–Atrioventricular Node ablation significantly improved echocardiographic measurements and New York Heart Association classification and reduced diuretics use for heart failure management in atrial fibrillation patients with narrow QRS who suffered from heart failure with preserved or reduced ejection fraction.
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benefits of permanent his bundle pacing combined with Atrioventricular Node ablation in atrial fibrillation patients with heart failure with both preserved and reduced left ventricular ejection fraction
Journal of the American Heart Association, 2017Co-Authors: Weijian Huang, Fangyi Xiao, Xiaohong Zhou, Kenneth A EllenbogenAbstract:Background Clinical benefits from His bundle pacing (HBP) in heart failure patients with preserved and reduced left ventricular ejection fraction are still inconclusive. This study evaluated clinical outcomes of permanent HBP in atrial fibrillation patients with narrow QRS who underwent Atrioventricular Node ablation for heart failure symptoms despite rate control by medication. Methods and Results The study enrolled 52 consecutive heart failure patients who underwent attempted Atrioventricular Node ablation and HBP for symptomatic atrial fibrillation. Echocardiographic left ventricular ejection fraction and left ventricular end‐diastolic dimension, New York Heart Association classification and use of diuretics for heart failure were assessed during follow‐up visits after permanent HBP. Of 52 patients, 42 patients (80.8%) received permanent HBP and Atrioventricular Node ablation with a median 20‐month follow‐up. There was no significant change between native and paced QRS duration (107.1±25.8 versus 105.3±23.9 milliseconds, P =0.07). Left ventricular end‐diastolic dimension decreased from the baseline ( P <0.001), and left ventricular ejection fraction increased from baseline ( P <0.001) in patients with a greater improvement in heart failure with reduced ejection fraction patients (N=20) than in heart failure with preserved ejection fraction patients (N=22). New York Heart Association classification improved from a baseline 2.9±0.6 to 1.4±0.4 after HBP in heart failure with reduced ejection fraction patients and from a baseline 2.7±0.6 to 1.4±0.5 after HBP in heart failure with preserved ejection fraction patients. After 1 year of HBP, the numbers of patients who used diuretics for heart failure decreased significantly ( P <0.001) when compared to the baseline diuretics use. Conclusions Permanent HBP post–Atrioventricular Node ablation significantly improved echocardiographic measurements and New York Heart Association classification and reduced diuretics use for heart failure management in atrial fibrillation patients with narrow QRS who suffered from heart failure with preserved or reduced ejection fraction.
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tachycardia related cardiomyopathy a common cause of ventricular dysfunction in patients with atrial fibrillation referred for Atrioventricular ablation
Mayo Clinic Proceedings, 2000Co-Authors: Margaret M Redfield, Louise S Jenkins, Marcus Mianulli, Nick D Jensen, Kenneth A EllenbogenAbstract:Objective To determine the frequency of tachycardia-related cardiomyopathy in patients with atrial fibrillation and systolic dysfunction referred for Atrioventricular Node ablation . Patients and Methods This prospective multicenter cohort study was conducted at 16 tertiary care centers. The ejection fraction was measured before and 3 and 12 months after Atrioventricular Node ablation. Patients with reduced systolic function (ejection fraction ≤45 %) before Atrioventricular ablation were included in this study. Patients whose ejection fraction increased by at least 15 percentage points and to higher than 45% were considered to have tachycardia-related cardiomyopathy. Results Of 63 patients with systolic dysfunction, 48 had at least 1 adequate follow-up echocardiographic study. Sixteen (25%) of the 63 had marked improvement in the ejection fraction (mean ± SD change, 2718 percentage points) to a value higher than 45% after ablation. Conclusions Tachycardia-related cardiomyopathy is common in patients with atrial fibrillation and systolic dysfunction referred for Atrioventricular Node ablation. This diagnosis should be considered in all patients in whom systolic dysfunction occurs subsequent to or concomitant with onset of atrial fibrillation.
Eric N Prystowsky - One of the best experts on this subject based on the ideXlab platform.
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differentiating Atrioventricular reentry tachycardia and Atrioventricular Node reentry tachycardia using premature his bundle complexes
Circulation-arrhythmia and Electrophysiology, 2020Co-Authors: Benzy J Padanilam, Asim Ahmed, Brad A Clark, Jasen Lee Gilge, Parin J Patel, Eric N Prystowsky, Leonard A SteinbergAbstract:Background: Current maneuvers for differentiation of Atrioventricular Node reentry tachycardia (AVNRT) and Atrioventricular reentry tachycardia (AVRT) lack sensitivity and specificity for AVRT circ...
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differentiating junctional tachycardia and Atrioventricular Node re entry tachycardia based on response to atrial extrastimulus pacing
Journal of the American College of Cardiology, 2008Co-Authors: Benzy J Padanilam, Leonard A Steinberg, Joseph A Manfredi, Jeff A Olson, Richard I Fogel, Eric N PrystowskyAbstract:Objectives The purpose of this study was to differentiate non–re-entrant junctional tachycardia (JT) and typical Atrioventricular Node re-entry tachycardia (AVNRT). Background JT may mimic AVNRT. Ablation of JT is associated with a lower success rate and a higher incidence of heart block. Electrophysiologic differentiation of these tachycardias is often difficult. Methods We hypothesized that JT can be distinguished from AVNRT based on specific responses to premature atrial complexes (PACs) delivered at different phases of the tachycardia cycle: when a PAC is timed to His refractoriness, any perturbation of the subsequent His indicates that anterograde slow pathway conduction is involved and confirms a diagnosis of AVNRT. A PAC that advances the His potential immediately after it without terminating tachycardia indicates that retrograde fast pathway is not essential for the circuit and confirms a diagnosis of JT. This protocol was tested in 39 patients with 44 tachycardias suggesting either JT or AVNRT based on a short ventriculo-atrial interval and apparent AV Node dependence. Tachycardias were divided into 3 groups: clinically obvious AVNRT, clinically obvious JT, and clinically indeterminate rhythm. Results In the 26 cases of clinically obvious AVNRT, the sensitivity and specificity of the test were 61% and 100%, respectively. In the 9 cases of clinically obvious JT, the sensitivity and specificity were 100% and 100%, respectively. In the 9 cases of clinically indeterminate rhythm, the technique indicated AVNRT in 1 patient and JT in 7 patients, and the test was indeterminate in 1 patient. Conclusions The response to PACs during tachycardia can distinguish JT and AVNRT with 100% specificity in adult patients.
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differentiating junctional tachycardia and Atrioventricular Node re entry tachycardia based on response to atrial extrastimulus pacing
Journal of the American College of Cardiology, 2008Co-Authors: Benzy J Padanilam, Leonard A Steinberg, Joseph A Manfredi, Jeff A Olson, Richard I Fogel, Eric N PrystowskyAbstract:Objectives The purpose of this study was to differentiate non–re-entrant junctional tachycardia (JT) and typical Atrioventricular Node re-entry tachycardia (AVNRT). Background JT may mimic AVNRT. Ablation of JT is associated with a lower success rate and a higher incidence of heart block. Electrophysiologic differentiation of these tachycardias is often difficult. Methods We hypothesized that JT can be distinguished from AVNRT based on specific responses to premature atrial complexes (PACs) delivered at different phases of the tachycardia cycle: when a PAC is timed to His refractoriness, any perturbation of the subsequent His indicates that anterograde slow pathway conduction is involved and confirms a diagnosis of AVNRT. A PAC that advances the His potential immediately after it without terminating tachycardia indicates that retrograde fast pathway is not essential for the circuit and confirms a diagnosis of JT. This protocol was tested in 39 patients with 44 tachycardias suggesting either JT or AVNRT based on a short ventriculo-atrial interval and apparent AV Node dependence. Tachycardias were divided into 3 groups: clinically obvious AVNRT, clinically obvious JT, and clinically indeterminate rhythm. Results In the 26 cases of clinically obvious AVNRT, the sensitivity and specificity of the test were 61% and 100%, respectively. In the 9 cases of clinically obvious JT, the sensitivity and specificity were 100% and 100%, respectively. In the 9 cases of clinically indeterminate rhythm, the technique indicated AVNRT in 1 patient and JT in 7 patients, and the test was indeterminate in 1 patient. Conclusions The response to PACs during tachycardia can distinguish JT and AVNRT with 100% specificity in adult patients.
Leonard A Steinberg - One of the best experts on this subject based on the ideXlab platform.
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differentiating Atrioventricular reentry tachycardia and Atrioventricular Node reentry tachycardia using premature his bundle complexes
Circulation-arrhythmia and Electrophysiology, 2020Co-Authors: Benzy J Padanilam, Asim Ahmed, Brad A Clark, Jasen Lee Gilge, Parin J Patel, Eric N Prystowsky, Leonard A SteinbergAbstract:Background: Current maneuvers for differentiation of Atrioventricular Node reentry tachycardia (AVNRT) and Atrioventricular reentry tachycardia (AVRT) lack sensitivity and specificity for AVRT circ...
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differentiating junctional tachycardia and Atrioventricular Node re entry tachycardia based on response to atrial extrastimulus pacing
Journal of the American College of Cardiology, 2008Co-Authors: Benzy J Padanilam, Leonard A Steinberg, Joseph A Manfredi, Jeff A Olson, Richard I Fogel, Eric N PrystowskyAbstract:Objectives The purpose of this study was to differentiate non–re-entrant junctional tachycardia (JT) and typical Atrioventricular Node re-entry tachycardia (AVNRT). Background JT may mimic AVNRT. Ablation of JT is associated with a lower success rate and a higher incidence of heart block. Electrophysiologic differentiation of these tachycardias is often difficult. Methods We hypothesized that JT can be distinguished from AVNRT based on specific responses to premature atrial complexes (PACs) delivered at different phases of the tachycardia cycle: when a PAC is timed to His refractoriness, any perturbation of the subsequent His indicates that anterograde slow pathway conduction is involved and confirms a diagnosis of AVNRT. A PAC that advances the His potential immediately after it without terminating tachycardia indicates that retrograde fast pathway is not essential for the circuit and confirms a diagnosis of JT. This protocol was tested in 39 patients with 44 tachycardias suggesting either JT or AVNRT based on a short ventriculo-atrial interval and apparent AV Node dependence. Tachycardias were divided into 3 groups: clinically obvious AVNRT, clinically obvious JT, and clinically indeterminate rhythm. Results In the 26 cases of clinically obvious AVNRT, the sensitivity and specificity of the test were 61% and 100%, respectively. In the 9 cases of clinically obvious JT, the sensitivity and specificity were 100% and 100%, respectively. In the 9 cases of clinically indeterminate rhythm, the technique indicated AVNRT in 1 patient and JT in 7 patients, and the test was indeterminate in 1 patient. Conclusions The response to PACs during tachycardia can distinguish JT and AVNRT with 100% specificity in adult patients.
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differentiating junctional tachycardia and Atrioventricular Node re entry tachycardia based on response to atrial extrastimulus pacing
Journal of the American College of Cardiology, 2008Co-Authors: Benzy J Padanilam, Leonard A Steinberg, Joseph A Manfredi, Jeff A Olson, Richard I Fogel, Eric N PrystowskyAbstract:Objectives The purpose of this study was to differentiate non–re-entrant junctional tachycardia (JT) and typical Atrioventricular Node re-entry tachycardia (AVNRT). Background JT may mimic AVNRT. Ablation of JT is associated with a lower success rate and a higher incidence of heart block. Electrophysiologic differentiation of these tachycardias is often difficult. Methods We hypothesized that JT can be distinguished from AVNRT based on specific responses to premature atrial complexes (PACs) delivered at different phases of the tachycardia cycle: when a PAC is timed to His refractoriness, any perturbation of the subsequent His indicates that anterograde slow pathway conduction is involved and confirms a diagnosis of AVNRT. A PAC that advances the His potential immediately after it without terminating tachycardia indicates that retrograde fast pathway is not essential for the circuit and confirms a diagnosis of JT. This protocol was tested in 39 patients with 44 tachycardias suggesting either JT or AVNRT based on a short ventriculo-atrial interval and apparent AV Node dependence. Tachycardias were divided into 3 groups: clinically obvious AVNRT, clinically obvious JT, and clinically indeterminate rhythm. Results In the 26 cases of clinically obvious AVNRT, the sensitivity and specificity of the test were 61% and 100%, respectively. In the 9 cases of clinically obvious JT, the sensitivity and specificity were 100% and 100%, respectively. In the 9 cases of clinically indeterminate rhythm, the technique indicated AVNRT in 1 patient and JT in 7 patients, and the test was indeterminate in 1 patient. Conclusions The response to PACs during tachycardia can distinguish JT and AVNRT with 100% specificity in adult patients.
Benzy J Padanilam - One of the best experts on this subject based on the ideXlab platform.
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differentiating Atrioventricular reentry tachycardia and Atrioventricular Node reentry tachycardia using premature his bundle complexes
Circulation-arrhythmia and Electrophysiology, 2020Co-Authors: Benzy J Padanilam, Asim Ahmed, Brad A Clark, Jasen Lee Gilge, Parin J Patel, Eric N Prystowsky, Leonard A SteinbergAbstract:Background: Current maneuvers for differentiation of Atrioventricular Node reentry tachycardia (AVNRT) and Atrioventricular reentry tachycardia (AVRT) lack sensitivity and specificity for AVRT circ...
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differentiating junctional tachycardia and Atrioventricular Node re entry tachycardia based on response to atrial extrastimulus pacing
Journal of the American College of Cardiology, 2008Co-Authors: Benzy J Padanilam, Leonard A Steinberg, Joseph A Manfredi, Jeff A Olson, Richard I Fogel, Eric N PrystowskyAbstract:Objectives The purpose of this study was to differentiate non–re-entrant junctional tachycardia (JT) and typical Atrioventricular Node re-entry tachycardia (AVNRT). Background JT may mimic AVNRT. Ablation of JT is associated with a lower success rate and a higher incidence of heart block. Electrophysiologic differentiation of these tachycardias is often difficult. Methods We hypothesized that JT can be distinguished from AVNRT based on specific responses to premature atrial complexes (PACs) delivered at different phases of the tachycardia cycle: when a PAC is timed to His refractoriness, any perturbation of the subsequent His indicates that anterograde slow pathway conduction is involved and confirms a diagnosis of AVNRT. A PAC that advances the His potential immediately after it without terminating tachycardia indicates that retrograde fast pathway is not essential for the circuit and confirms a diagnosis of JT. This protocol was tested in 39 patients with 44 tachycardias suggesting either JT or AVNRT based on a short ventriculo-atrial interval and apparent AV Node dependence. Tachycardias were divided into 3 groups: clinically obvious AVNRT, clinically obvious JT, and clinically indeterminate rhythm. Results In the 26 cases of clinically obvious AVNRT, the sensitivity and specificity of the test were 61% and 100%, respectively. In the 9 cases of clinically obvious JT, the sensitivity and specificity were 100% and 100%, respectively. In the 9 cases of clinically indeterminate rhythm, the technique indicated AVNRT in 1 patient and JT in 7 patients, and the test was indeterminate in 1 patient. Conclusions The response to PACs during tachycardia can distinguish JT and AVNRT with 100% specificity in adult patients.
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differentiating junctional tachycardia and Atrioventricular Node re entry tachycardia based on response to atrial extrastimulus pacing
Journal of the American College of Cardiology, 2008Co-Authors: Benzy J Padanilam, Leonard A Steinberg, Joseph A Manfredi, Jeff A Olson, Richard I Fogel, Eric N PrystowskyAbstract:Objectives The purpose of this study was to differentiate non–re-entrant junctional tachycardia (JT) and typical Atrioventricular Node re-entry tachycardia (AVNRT). Background JT may mimic AVNRT. Ablation of JT is associated with a lower success rate and a higher incidence of heart block. Electrophysiologic differentiation of these tachycardias is often difficult. Methods We hypothesized that JT can be distinguished from AVNRT based on specific responses to premature atrial complexes (PACs) delivered at different phases of the tachycardia cycle: when a PAC is timed to His refractoriness, any perturbation of the subsequent His indicates that anterograde slow pathway conduction is involved and confirms a diagnosis of AVNRT. A PAC that advances the His potential immediately after it without terminating tachycardia indicates that retrograde fast pathway is not essential for the circuit and confirms a diagnosis of JT. This protocol was tested in 39 patients with 44 tachycardias suggesting either JT or AVNRT based on a short ventriculo-atrial interval and apparent AV Node dependence. Tachycardias were divided into 3 groups: clinically obvious AVNRT, clinically obvious JT, and clinically indeterminate rhythm. Results In the 26 cases of clinically obvious AVNRT, the sensitivity and specificity of the test were 61% and 100%, respectively. In the 9 cases of clinically obvious JT, the sensitivity and specificity were 100% and 100%, respectively. In the 9 cases of clinically indeterminate rhythm, the technique indicated AVNRT in 1 patient and JT in 7 patients, and the test was indeterminate in 1 patient. Conclusions The response to PACs during tachycardia can distinguish JT and AVNRT with 100% specificity in adult patients.
Mark R Boyett - One of the best experts on this subject based on the ideXlab platform.
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Three-Dimensional Computer Model of the Right Atrium Including the Sinoatrial and Atrioventricular Nodes Predicts Classical Nodal Behaviours
2016Co-Authors: Shin Inada, Halina Dobrzynski, Henggui Zhang, Jurgen E. Schneider, Mark R BoyettAbstract:The aim of the study was to develop a three-dimensional (3D) anatomically-detailed model of the rabbit right atrium containing the sinoatrial and Atrioventricular Nodes to study the electrophysiology of the Nodes. A model was generated based on 3D images of a rabbit heart (atria and part of ventricles), obtained using high-resolution magnetic resonance imaging. Segmentation was carried out semi-manually. A 3D right atrium array model (,3.16 million elements), including eighteen objects, was constructed. For description of cellular electrophysiology, the Rogers-modified FitzHugh-Nagumo model was further modified to allow control of the major characteristics of the action potential with relatively low computational resource requirements. Model parameters were chosen to simulate the action potentials in the sinoatrial Node, atrial muscle, inferior nodal extension and penetrating bundle. The block zone was simulated as passive tissue. The sinoatrial Node, crista terminalis, main branch and roof bundle were considered as anisotropic. We have simulated normal and abnormal electrophysiology of the two Nodes. In accordance with experimental findings: (i) during sinus rhythm, conduction occurs down the interatrial septum and into the Atrioventricular Node via the fast pathway (conduction down the crista terminalis and into the Atrioventricular Node via the slow pathway is slower); (ii) during atrial fibrillation, the sinoatrial Node is protected from overdrive by its long refractory period; and (iii) during atrial fibrillation, the Atrioventricular Node reduces the frequency of action potentials reaching the ventricles. The model is able to simulate ventricular ech
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characterization and influence of cardiac background sodium current in the Atrioventricular Node
Journal of Molecular and Cellular Cardiology, 2016Co-Authors: Hongwei Cheng, Stéphanie C.m. Choisy, Andrew F. James, Mark R Boyett, Shin Inada, Henggui Zhang, Clive H Orchard, Jules C. HancoxAbstract:Background inward sodium current (IB,Na) that influences cardiac pacemaking has been comparatively under-investigated. The aim of this study was to determine for the first time the properties and role of IB,Na in cells from the heart's secondary pacemaker, the Atrioventricular Node (AVN). Myocytes were isolated from the AVN of adult male rabbits and mice using mechanical and enzymatic dispersion. Background current was measured using whole-cell patch clamp and monovalent ion substitution with major voltage- and time-dependent conductances inhibited. In the absence of a selective pharmacological inhibitor of IB,Na, computer modelling was used to assess the physiological contribution of IB,Na. Net background current during voltage ramps was linear, reversing close to 0 mV. Switching between Tris- and Na+-containing extracellular solution in rabbit and mouse AVN cells revealed an inward IB,Na, with an increase in slope conductance in rabbit cells at − 50 mV from 0.54 ± 0.03 to 0.91 ± 0.05 nS (mean ± SEM; n = 61 cells). IB,Na magnitude varied in proportion to [Na+]o. Other monovalent cations could substitute for Na+ (Rb+ > K+ > Cs+ > Na+ > Li+). The single-channel conductance with Na+ as charge carrier estimated from noise-analysis was 3.2 ± 1.2 pS (n = 6). Ni2 + (10 mM), Gd3 + (100 μM), ruthenium red (100 μM), or amiloride (1 mM) produced modest reductions in IB,Na. Flufenamic acid was without significant effect, whilst La3 + (100 μM) or extracellular acidosis (pH 6.3) inhibited the current by > 60%. Under the conditions of our AVN cell simulations, removal of IB,Na arrested spontaneous activity and, in a simulated 1D-strand, reduced conduction velocity by ~ 20%. IB,Na is carried by distinct low conductance monovalent non-selective cation channels and can influence AVN spontaneous activity and conduction.
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Connexins and the Atrioventricular Node
Heart rhythm, 2012Co-Authors: Ian P. Temple, Shin Inada, Halina Dobrzynski, Mark R BoyettAbstract:The structure and functioning of the Atrioventricular (AV) Node has remained mysterious owing to its high degree of complexity. In this review article, we integrate advances in knowledge regarding connexin expression in the AV Node. Complex patterning of 4 different connexin isoforms with single channel conductances ranging from ultralow to high explains the dual pathway electrophysiology of the AV Node, the presence of 2 nodal extensions, longitudinal dissociation in the penetrating bundle, and, most importantly, how the AV Node maintains slow conduction between the atria and the ventricles. It is shown that the complex patterning of connexins is the consequence of the embryonic development of the cardiac conduction system. Finally, it is argued that connexin dysregulation may be responsible for AV Node dysfunction.
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one dimensional mathematical model of the Atrioventricular Node including atrio nodal nodal and nodal his cells
Biophysical Journal, 2009Co-Authors: Shin Inada, Jules C. Hancox, Henggui Zhang, Mark R BoyettAbstract:Mathematical models are a repository of knowledge as well as research and teaching tools. Although action potential models have been developed for most regions of the heart, there is no model for the Atrioventricular Node (AVN). We have developed action potential models for single atrio-nodal, nodal, and nodal-His cells. The models have the same action potential shapes and refractoriness as observed in experiments. 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. The multicellular model has slow and fast pathways into the AVN and using it we have analyzed the rich behavior of the AVN. Under normal conditions, action potentials were initiated in the SAN center and then propagated through the atrium and AVN. The relationship between the AVN conduction time and the timing of a premature stimulus (conduction curve) is consistent with experimental data. After premature stimulation, Atrioventricular nodal reentry could occur. After slow pathway ablation or block of the L-type Ca2+ current, Atrioventricular nodal reentry was abolished. During atrial fibrillation, the AVN limited the number of action potentials transmitted to the ventricle. In the absence of SAN pacemaking, the inferior nodal extension acted as the pacemaker. In conclusion, we have developed what we believe is the first detailed mathematical model of the AVN and it shows the typical physiological and pathophysiological characteristics of the tissue. The model can be used as a tool to analyze the complex structure and behavior of the AVN.
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ion channel transcript expression at the rabbit Atrioventricular conduction axis
Circulation-arrhythmia and Electrophysiology, 2009Co-Authors: I D Greener, James O Tellez, Halina Dobrzynski, Mitsuru Yamamoto, Gillian M Graham, Rudi Billeter, Mark R BoyettAbstract:Background— Little is known about the distribution of gap junctions and ion channels in the Atrioventricular Node, even though the physiology and pathology of the Atrioventricular Node is ultimately dependent on them. Methods and Results— The abundance of 30 transcripts for markers, gap junctions, ion channels, and Ca2+-handling proteins in different regions of the rabbit Atrioventricular Node (nodal extension and proximal and distal penetrating bundle of His as well as atrial and ventricular muscle) was measured using a novel quantitative polymerase chain reaction technique and in situ hybridization. The expression profile of the nodal extension (slow pathway into penetrating bundle) was similar to that of the sinoatrial Node. For example, in the nodal extension, in contrast to the atrial muscle and as expected for a slowly conducting tissue with pacemaker activity, there was no or reduced expression of Cx43, Nav1.5, Cav1.2, Kv1.4, KChIP2, and RYR3 and high expression of Cav1.3 and HCN4. The expression profile of the penetrating bundle was less specialized. In situ hybridization revealed a transitional zone with reduced expression of Cx43, Nav1.5, and KChIP2 that may form the fast pathway into the penetrating bundle. Conclusions— At the Atrioventricular Node, the expression of gap junctions and ion channels in the nodal extension (slow pathway) and a transitional zone (putative fast pathway) as well as the penetrating bundle (output pathway) is specialized and heterogeneous and roughly matches the electrophysiology of the different regions. Received January 28, 2008; accepted February 4, 2009.