The mechanisms responsible for atrioventricular (AV) delay remain unclear, in part due to the inability to map electrical activity by conventional microelectrode techniques. In this study, voltage-sensitive dyes and imaging techniques were refined to detect action potentials (APs) from the small cells comprising the AV node and to map activation from the "compact" node. Optical APs (124) were r...

The spread of excitation wave fronts over the atrial septum of puppies, adult dogs, and rabbits was studied in vitro by extracellular measurements with a 50/x-diameter electrode. Wave front spread through the AV node of puppies and rabbits was determined, and the functional location of the junctional region between atrial muscle and the AV node was evaluated during antegrade atrial and retrogra...

BACKGROUND The term "concealed conduction" is used in electrocardiography when a proximal (atrial or ventricular) impulse penetrates the atrioventricular (AV) node but fails to traverse it completely. Its penetration into the node is inferred by its after effects on the propagation of succeeding impulses. Concealed AV nodal conduction is a well-established phenomenon, but its precise cellular a...

The effects of verapamil, an antiarrhythmic drug that apparently blocks slow inward currents, were studied on the isolated, superfused sinoatrial (SA) and atrioventricular (AV) nodes of the rabbit heart with intracellular microelectrodes. Verapamil decreased the rate of spontaneous impulse initiation by the SA node. This effect could be overcome with epinephrine. Concomitantly, verapamil decrea...

Circus movements within the AV node as a basis for supraventricular tachycardia as shown by multiple microelectrode recording in the isolated rabbit heart – M. J. Janse and others A subpopulation of cells with unique electrophysiological properties in the deep subepicardium of the canine ventricle. The M cell – S. Sicouri, C. Antzelevitch Membrane current through adenosine-triphosphate–regulate...

introduction: intranodal pathways of atrioventricular (av) node play a vital role in the delay of conduction time in response to various atrial inputs. the present study was aimed to determine the frequency-dependent electrophysiological properties of concealed slow pathway according to a functional model of isolated rabbit atrioventricular node preparation after fast pathway ablation. methods:...

We report results obtained with sera from 58 chronic chagasic patients that were evaluated for effects on heart rate and atrioventricular (AV) conduction in isolated rabbit hearts and screened for the presence of muscarinic and beta-adrenergic activity. We show that sera from 26 patients decreased heart rate, while 10 increased it and 22 had no effect. Additionally, sera from 20 of the 58 patie...

Anatomy of the cardiac conduction system was studied in 15 rabbits with serial histologic sectioning of 4. The rabbit's sinus node is a simple and distinct structure located at the junction of the crista terminalis with the sinus intercavarum nearly midway between the two cavae; it contains an unusually large percentage of P cells but is not organized about a large central artery. The AV node a...