Tachycardias that are successfully ablated in the vicinity of the atrioventricular (AV) node are common, and although frequently successfully treated, are among the most difficult arrhythmias to understand in cardiac electrophysiology. Even AV node reentrant tachycardia (AVNRT), despite near universal cure, is complex with the anatomic constructs for typical, atypical forms, left-sided AVNRT, u...

The reentrant pathways underlying different types of atrioventricular (AV) nodal reentrant tachycardia have not yet been elucidated. This study was performed to optically map Koch's triangle and surrounding atrial tissue in an isolated canine AV nodal preparation. Multiple preferential AV nodal input pathways were observed in all preparations (n=22) with continuous (73%, n=16) and discontinuous...

Previous studies have demonstrated that the extracellular space (ECS) component of the atrioventricular (AV) node and His bundle region is larger than the ECS in adjacent contractile myocardium. The potential physiological significance of this observation was examined in a canine blood-perfused AV nodal preparation. Mannitol, an ECS osmotic expander, was infused directly into either the AV node...

Cardiac and coronary vasodilator effects of gentamicin (GM) were investigated in isolated, blood-perfused papillary muscle, sino-atrial (SA) node and atrioventricular (AV) node preparations of dogs. GM (0.3-100 mumol) was injected intraarterially. GM produced an increase in coronary blood flow in all preparations. In paced papillary muscle preparations, GM reduced the force of contraction. In s...

Tachycardias that are successfully ablated in the vicinity of the atrioventricular (AV) node are common, and although frequently successfully treated, are among the most difficult arrhythmias to understand in cardiac electrophysiology. Even AV node reentrant tachycardia (AVNRT), despite near universal cure, is complex with the anatomic constructs for typical, atypical forms, left-sided AVNRT, u...

Introduction: Electrophysiological studies have demonstrated a relationship between aging and atrioventricular (AV) nodal conduction and refractoriness. The aim of the present study was to determine the effects of nodal aging on dynamic AV nodal field potential recording during atrial fibrillation (AF) in rabbit. Methods: Two groups of male New Zealand rabbits (neonatal 2-week-olds and adult...

We used intracellular microelectrodes to study the effects of hypoxia on the isolated, superfused sinoatrial (SA) node, atrium, and atrioventricular (AV) node of the rabbit heart. Hypoxia decreased the rate of spontaneous impulse initiation in SA nodal fibers by decreasing the slope of diastolic depolarization. With gradually decreasing Po2, the sinus rate was reduced; concomitantly, the correc...

OBJECTIVES This study sought to investigate electrophysiologic characteristics and possible anatomic sites of multiple anterograde slow atrioventricular (AV) node pathways and to compare these findings with those in dual anterograde AV node pathways. BACKGROUND Although multiple anterograde AV node pathways have been demonstrated by the presence of multiple discontinuities in the AV node cond...

The mechanisms responsible for slowing cardiac impulse conduction through the atrioventricular (AV) node are not well understood but include anatomical architecture, presence of cells with diverse electrophysiological characteristics, and modulation by autonomic nervous system. The present study was designed to determine the site of vagally induced slowing of conduction through the AV node. We ...

Diltiazem, verapamil and nifedipine suppress sinoatrial (SA) nodal function in the excised rabbit heart. Clinically, however, their suppressive effect on the SA node is modified considerably by the reflex increase in sympathetic tone as a result of the fall in blood pressure caused by the vasodilating action of the calcium antagonists. Diltiazem, verapamil and nifedipine suppress atrioventricul...