Incidence and clinical significance of repetitive ventricular response in patients without identifiable organic heart disease.

We determined the incidence of repetitive ventricular response (RVR) after programmed electrical stimulation and the incidence of spontaneous ventricular arrhythmias during 24 hr Holter monitoring in 38 patients in whom extensive non-invasive and invasive diagnostic tests had excluded abnormalities suggestive of organic heart disease. A standardized stimulation protocol with single (S1S2) and double (S1S2S3) extrastimuli during ventricular drive at cycle lengths of 600, 500 and 430 msec with a current strength below 5 mA at the right ventricular apex was employed. RVR occurred in 20 patients (58%) after S1S2 and in 30 patients (79%) after S1S2S3 stimulation. Eighteen patients (47%) showed RVR with 2 echo beats and 1 patient had 3 echo beats. RVR was due to bundle branch reentry (BBR) in 20 patients independent of the mode of stimulation. RVR due to intraventricular reentry (IVR) was found in 17 patients (47%) only after S1S2S3 stimulation. The incidence of both BBR and IVR was influenced by the basic ventricular driving rate, decreasing with shorter basic cycle lengths. 17 patients had no ventricular premature depolarizations (VPDs), 12 patients had uniform, 4 multiform (Lown III), 2 consecutive (Lown IVA) VPDs, and 1 patient had parasystolic rhythm. There was no relation to the incidence of repetitive ventricular response. We conclude that in patients without identifiable organic heart disease RVR with more than 2 consecutive beats is rarely found if single and double extrastimuli are employed during ventricular drive. Both bundle branch and intraventricular reentry with one or two echo beats are a common finding in this population without relation to the incidence of spontaneous ventricular arrhythmias.