[Retrograde conduction (ventriculo-atrial) in patients with AV or intraventricular block. Electrophysiologic evaluation]

Abstract

The purpose of the study was to evaluate ventriculoatrial conduction in patients with chronic complete AV block (AVB) (35 pts--gr. A), who were qualified for pacemaker implantation and in patients with bifascicular block (BFB) (20 pts--gr. B), who had electrophysiological study performed to determine indications for permanent pacing. Anterograde and retrograde conduction by accessory pathways were excluded in all patients. Incremental ventricular pacing (60-80 bpm to 200-220 bpm) and programmed ventricular stimulation were performed. Ventriculoatrial (VA) conduction was present in 12 of 35 patients in gr. A (34%) and in 15/20 patients in gr. B (75%). Mean VA conduction time was 192 +/- 50 ms in gr. A and 200 +/- 54 ms in gr. B, effective refractory period of right ventricle (ERP-RV) was 270 +/- 30 ms and 250 +/- 29 ms respectively. Mean retrograde Wenckebach point was 128 +/- 41 bpm in gr. A and 132 +/- 30 bpm in gr. B. The level of VA Wenckebach block in gr. A was found at AVN in 4 of 12 patients and in remaining was not directly recognised. Levels in gr. B were: AVN--6, not recognised--9 patients. Ventriculoatrial conduction shows complex properties and dependence on the type of ventricular stimulation. Electrophysiological study enables to find a level of retrograde block in some patients.