Electrophysiologic evaluation of sinus node function and atrioventricular conduction in patients with prolonged ventricular asystole during obstructive sleep apnea.

In 15 patients with ventricular asystole of 8.5 +/- 3.5 seconds (range 5.0 to 16.8) occurring exclusively during obstructive sleep apnea, electrophysiologic study of sinus node function and atrioventricular conduction before and after administration of intravenous atropine (0.02 mg/kg) was performed. Electrophysiologic parameters of sinus node function were normal in 12 of 15 patients (80%) and atrioventricular (AV) nodal function was normal in 7 patients (47%). Almost all abnormal findings of sinus node function and AV nodal function were reversible by administration of atropine. The HisPurkinje system function was normal in 6 patients (40%). Prolonged HV intervals (57 to 73 ms) were found in 9 patients (60%). Intra- or infra-His block was not observed in any patient. In summary, electrophysiologic parameters of sinus node function and AV conduction were normal or only slightly abnormal in all 15 study patients, which suggests that prolonged ventricular asystole during obstructive sleep apnea is not due to fixed or anatomic disease of the sinus node or the AV conduction system.