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Trends in Cardiovascular Medicine Jul 2010The sinus node generates the electrical impulse, which spreads rapidly over both atria, causing them to contract simultaneously. In the normal heart, a layer of... (Review)
Review
The sinus node generates the electrical impulse, which spreads rapidly over both atria, causing them to contract simultaneously. In the normal heart, a layer of connective tissue electrically insulates the atria and ventricles. The only pathway that crosses this plane is the atrioventricular conduction axis, through which the impulse reaches the ventricles. Within the axis, the atrioventricular node delays the impulse, allowing the ventricles to be filled before their contraction is initiated. Moreover, the atrioventricular node protects the ventricles from rapid atrial arrhythmias and may take over pacemaker function when the sinus node fails. In pathological conditions, these complex physiological properties contribute to several types of arrhythmias that originate from the atrioventricular conduction system. One example is atrioventricular block, which requires electronic pacemaker implantation because there is currently no cure for this arrhythmia. Because conduction system defects may arise during embryonic development, the mechanisms of conduction system development have been intensively studied. Nevertheless, its developmental origin, molecular composition, and phenotype have remained fertile subjects of research and debate. Lineage and expressional analyses have indicated that the atrioventricular node develops from a subpopulation of precursor cells in the dorsal part of the embryonic atrioventricular canal. These cells become distinct early in development, are less well differentiated compared to the developing working myocardium, and, in addition to their cardiogenic gene program, activate and maintain a neurogenic gene program.
Topics: Atrioventricular Node; Growth and Development; Heart Conduction System; Humans
PubMed: 21742272
DOI: 10.1016/j.tcm.2011.02.001 -
Pacing and Clinical Electrophysiology :... Aug 1994With the advent of RF catheter modification of AV node conduction for the treatment of AV node reentrant tachycardia, considerable advances have been made with better... (Review)
Review
With the advent of RF catheter modification of AV node conduction for the treatment of AV node reentrant tachycardia, considerable advances have been made with better understanding of the AV junctional anatomy, electrophysiology, and mechanism responsible for AV node reentrant tachycardia. Future studies should be designed to uncover the basic cellular electrophysiological mechanisms responsible for fast and slow AV node conduction, to define the exact tissue components of the reentrant circuit in order to make ablative procedures safer, and to study the long-term effects of RF catheter ablation on AV conduction. Special caution should be directed toward pediatric patients with more stringent indications for catheter ablation of the AV junctional area in these patients.
Topics: Animals; Atrioventricular Node; Catheter Ablation; Electrocardiography; Electrophysiology; Humans; Tachycardia, Atrioventricular Nodal Reentry
PubMed: 7971402
DOI: 10.1111/j.1540-8159.1994.tb02461.x -
British Heart Journal Apr 1989
Review
Topics: Atrial Fibrillation; Atrioventricular Node; Biological Clocks; Heart Conduction System; Humans; Models, Biological; Tachycardia, Sinus
PubMed: 2653390
DOI: 10.1136/hrt.61.4.309 -
Critical Care Nursing Clinics of North... Sep 2016In this article, the authors outline the key components behind the automated generation of the cardiac impulses and the effect these impulses have on cardiac myocytes.... (Review)
Review
In this article, the authors outline the key components behind the automated generation of the cardiac impulses and the effect these impulses have on cardiac myocytes. Also, a description of the key components of the normal cardiac conduction system is provided, including the sinoatrial node, the atrioventricular node, the His bundle, the bundle branches, and the Purkinje network. Finally, an outline of how each stage of the cardiac conduction system is represented on the electrocardiogram is described, allowing the reader of the electrocardiogram to translate background information about the normal cardiac conduction system to everyday clinical practice.
Topics: Atrioventricular Node; Bundle of His; Critical Care Nursing; Electrocardiography; Heart Conduction System; Heart Rate; Humans; Sinoatrial Node
PubMed: 27484656
DOI: 10.1016/j.cnc.2016.04.001 -
Current Opinion in Cardiology Mar 2009Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common arrhythmia in patients with regular supraventricular tachycardia. Selective radio frequency... (Review)
Review
PURPOSE OF REVIEW
Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common arrhythmia in patients with regular supraventricular tachycardia. Selective radio frequency catheter ablation of the slow pathway has afforded an ideal method to treat most patients with AVNRT. However, there are still some controversies and recent developments concerning the ablation for patients with AVNRT. The purpose of this review is to elucidate the anatomy and physiology of the atrioventricular node and implications for the ablation of AVNRT.
RECENT FINDINGS
The sequential ablation sites for slow pathway ablation are suggested as the isthmus between tricuspid annulus and coronary sinus ostium, the tricuspid edge of coronary sinus ostium by moving the ablation catheter tip slightly in and out of the coronary sinus, the septum lower than coronary sinus ostium, moving higher up on the half of Koch's triangle along the septum, one or two burns inside the first centimeter of the coronary sinus, left side of the septum.
SUMMARY
It is imperative to recognize the detailed anatomy and physiology of the atrioventricular node in every individual patient before the ablation of AVNRT.
Topics: Adult; Atrioventricular Node; Catheter Ablation; Child; Electrophysiological Phenomena; Humans; Tachycardia, Atrioventricular Nodal Reentry
PubMed: 19225293
DOI: 10.1097/HCO.0b013e328323d83f -
Journal of Cardiovascular... Jul 2021
Topics: Atrioventricular Node; Humans; Tachycardia, Atrioventricular Nodal Reentry
PubMed: 34053142
DOI: 10.1111/jce.15118 -
Physiological Reviews Apr 1988The AV node of those mammalian species in which it has been thoroughly investigated (rabbit, ferret, and humans) consists of various cell types: transitional cells,... (Comparative Study)
Comparative Study Review
The AV node of those mammalian species in which it has been thoroughly investigated (rabbit, ferret, and humans) consists of various cell types: transitional cells, midnodal (or typical nodal cells), lower nodal cells, and cells of the AV bundle. There are at least two inputs to the AV node, a posterior one via the crista terminalis and an anterior one via the interatrial septum, where atrial fibers gradually merge with transitional cells. The role of a possible third input from the left atrium has not been investigated. Since the transition from atrial fibers to nodal fibers is gradual, it is very difficult to define the "beginning" of the AV node, and gross measurements of AV nodal length may be misleading. Histologically, the "end" of the AV node is equally difficult to define. At the site where macroscopically the AV node ends, at the point where the AV bundle penetrates into the membranous septum, typical nodal cells intermingle with His bundle cells. A conspicuous feature, found in all species studied, is the paucity of junctional complexes, most marked in the midnodal area. The functional counterpart of this is an increased coupling resistance between nodal cells. An electrophysiological classification of the AV nodal area, based on transmembrane action potential characteristics during various imposed atrial rhythms (rapid pacing, trains of premature impulses), into AN (including ANCO and ANL), N, and NH zones has been described by various authors for the rabbit heart. In those studies in which activation patterns, transmembrane potential characteristics, and histology have been compared, a good correlation has been found between AN and transitional cells, N cells and the area where transitional cells and cells of the beginning of the AV bundle merge with midnodal cells, and NH cells and cells of the AV bundle. Dead-end pathways correspond to the posterior extension of the bundle of lower nodal cells and to anterior overlay fibers. During propagation of a normal sinus beat, activation of the AN zone accounts for at least 25% of conduction time from atrium to His bundle, the small N zone being the main source of AV nodal delay. Cycle length-dependent conduction delay is localized in the N zone. Conduction block of premature atrial impulses can occur both in the N zone and in the AN zone, depending on the degree of prematurity. Several factors determining AV nodal conduction delay have been identified.(ABSTRACT TRUNCATED AT 400 WORDS)
Topics: Animals; Atrial Fibrillation; Atrioventricular Node; Biomechanical Phenomena; Cardiac Complexes, Premature; Electrophysiology; Heart Block; Heart Conduction System; Humans; Mammals; Nerve Fibers; Neural Conduction; Neurotransmitter Agents
PubMed: 2451833
DOI: 10.1152/physrev.1988.68.2.608 -
Journal of Cardiovascular... Nov 1998Concomitant with the development of catheter ablation techniques for the treatment of atrial arrhythmias, there is renewed interest in the morphologic arrangement of the... (Review)
Review
Concomitant with the development of catheter ablation techniques for the treatment of atrial arrhythmias, there is renewed interest in the morphologic arrangement of the cardiac conduction system. In this article, we revisit the anatomy of the specialized tissues, making special reference to the descriptions given at the time of their discovery. According to criteria for histologic distinction of morphologically specialized tracts set nearly 100 years ago, the penetrating bundle (of His) and the ventricular bundle branches are tracts of specialized cells encased by insulating sheaths of fibrous tissue. In contrast, the sinus and AV nodes are recognized histologically but are not insulated from the working atrial myocardium. At its distal extent, the AV node is distinguished from the penetrating bundle not so much by cellular characteristics, but by the presence of a fibrous collar that surrounds the specialized cells. At the atrial part, a zone of histologically transitional cells interposes between the compact node and the working atrial myocardium. Transitional cells enter the triangle of Koch to join the compact node from superiorly, inferiorly, posteriorly, and from the left. Transitional cells of the sinus node, in contrast, are limited to short tongues that interdigitate with musculature of the terminal crest. Apart from a variable extension of its tail, there are no prominent histologically discrete extensions from the sinus node into the working atrial musculature. The internodal myocardium does not contain discrete conducting tracts comparable with the ventricular bundle branches. Preferential conduction more likely reflects the arrangement of the working internodal cells and their related cellular properties.
Topics: Atrioventricular Node; Heart; Heart Conduction System; Humans; Sinoatrial Node
PubMed: 9835269
DOI: 10.1111/j.1540-8167.1998.tb00097.x -
Chinese Medical Journal Dec 2012Cystic tumour of the atrioventricular node is a rare primary cardiac tumour that can cause complete heart block and sudden death. Here, we describe a male case aged 42... (Review)
Review
Cystic tumour of the atrioventricular node is a rare primary cardiac tumour that can cause complete heart block and sudden death. Here, we describe a male case aged 42 years who suddenly died without a medical and family history of cardiac illnesses. After detailed macroscopic and microscopic examinations, a cystic mass was found in the atrioventricular nodal region. The small lesion was less than 1 cm in diameter, and consisted of small and large cystic spaces and tubular structures lined by flat, cuboidal or squamous epithelium. Immunohistochemical staining revealed the tumour epithelium positive for epithelial membrane antigen, carcinoembryonic antigen, antigen epitopes AE1/AE3, cytokeratins CK5/6 and CK7, but negative for calretinin, HBME-1, Wilms' tumor 1, factor VIII, chromogranin, synaptophysin or smooth muscle actin, suggesting an endodermal rather than mesothelial origin.
Topics: Adult; Atrioventricular Node; Heart Neoplasms; Humans; Immunohistochemistry; Male
PubMed: 23253729
DOI: No ID Found -
Medicine, Science, and the Law Apr 2023
Topics: Humans; Atrioventricular Node; Neoplasms
PubMed: 36373753
DOI: 10.1177/00258024221138748