Paroxysmal tachycardia with episodic unconsciousness.

Unconsciousness due to disturbed cardiac output is seen most often as a result of acquired heart block with unstable ventricular rhythm. Less often it occurs as a result of an arrhythmia which may appear to be primary or else be associated with some obvious cardiac disease. Although unconsciousness due to this cause is relatively uncommon, it is important that the basic condition be recognized. Two such cases are reported and discussed with particular reference to the unusual arrhythmias recorded. Case Reports