ALTERNATION OF PARTIAL AND TOTAL ATRIAL STANDSTILL

A 45 yr old man with longstanding rheumatic heart disease whose surface ECG showed absent P waves and 2 alternating QRS complex rhythms, 1 regular and the other irregular, was studied electrophysiologically. For regular QRS complex rhythm these studies revealed presence of total and bilateral atrial standstill and regular ventricular rhythm originating in the AV [atrioventricular] junction. For irregular QRS complex rhythm the studies showed presence of atrial standstill in the area of the upper right atrium, and approximately 150 beats/min atrial rate in the intracavitary and esophageal electrogram and 300 beats/min rate in the epicardial mapping. The spread of conduction of atrial activity showed that it originated within an atrial area near the tricuspid valve. The presence of an alternating partial and total atrial standstill is a unique feature which was not previously reported.