Persistent atrial standstill.

The authors present a case of permanent atrial standstill with syncopal attacks, in a patient with chronic Chagas' Heart Disease. The recognition of this dysrhythmia was based upon the conventional and intracavity electrocardiographic tracings in addition to phonomecanographic and hemodynamic data. The recording of the His Bundle electrogram demonstrated the absence of atrial activity, with the His potential preceding all ventricular complexes and an advanced conduction defect distal to the bundle of His. A diffuse type of atrial involvement was suggested by the lack of response to pacemaker stimulation. An increase in ventricular rate following intravenous atropine administration, led to the diagnosis of an a-v junctional rhythm with a widened QRS complex due to an associated right bundle branch block. Following the implantation of an epicardial ventricular pacemaker, the patient became completely asymptomatic despite the persistence of electrical and mechanical atrial standstill.