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Supraventricular paroxysmal tachycardia interrupted by repeated episodes of total cardiac standstill with syncopal attacks.

Periods of total cardiac standstill may interrupt bouts of supraventricular tachycardia and cause syncopal attacks especially in elderly persons. Three cases of this syndrome are reported, all based on a background of ischemic heart disease, but not obviously ischemic in origin. Infection and drugs which depress myocardial activity may in some cases be responsible for the pauses as shown in a review of the literature which reveals a few similar but less extreme examples of "total cardiac standstill" or "pacemaker block" during supraventricular tachycardia. Restoration of sinus rhythm abolishes the periods of total cardiac standstill.