Reflex cardiac asystole.

In this report we present the case of a patient with recurrent syncopal episodes. During one of the attacks the patient was monitored by telemetry and the ECG lead showed asystole for more than 7 seconds. As in cases of the cardioinhibitory type of hypersensitive carotid sinus syndrome (HCSS), asystole may represent suppression of the sinus node or suppression of both sinus and atrioventricular (AV) node. Unfortunately, in contrast to HCSS, there is no maneuver that can reproducibly induce episodes of asystole. Consequently, very little is known about the occurrence of AV block in the presence of sinus arrest. In the patient described in this report, we were able to demonstrate that suppression of sinus and AV nodes occurred simultaneously. It is interesting to note that in this type of syncope data from noninvasive and invasive techniques in assessing sinus nodal and AV nodal conduction may not be conclusive. In the group of patients with this type of syncope, permanent atrial demand pacing is contraindicated.