A Complication of an Implanted Electric Pacemaker.

T HIS 56-YEAR-OLD MAN WAS ADMITTED to Hahnemann Hospital because of frequent Adams-Stokes attacks. He had experienced an acute myocardial infarction in 1958 and again in 1961. Frequent convulsions occurred in spite of administration of atropine, isoproterenol, and chlorothiazide. On January 3, 1962, an electric pacemaker was implanted on the left ventricle. The following electrocardiographic strips are presented to illustrate an unusual combination of rhythms following the implantation of an electric pacemaker and to demonstrate the absolute refractory period of the human ventricle. 1. On admission (A) sinus tachycardia was present at l40/min. The ventricles are under control of a ventricular pacemaker (30/min.). Failure of the subsidary pacemaker engendered periods of asystole and Adarns-Stokes attacks. Following the insertion of the pacemaker (B) a regular ventricular response (60/min. ) was present. The atria are under control of the sinus node ( 100/min.) while the ventricles are entirely controlled by the electrical pacemaker.