Termination and Inhibition of Recurrent Tachycardias by Implanted Pervenous Pacemakers

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Abstract
Three patients are described with recurrent paroxysmal tachycardia who required implanted pervenous demand pacemakers for the control of repetitive tachyarrhythmias. One patient had frequent weekly episodes of life-inhibiting supraventricular tachycardia (SVT) lasting hours to days and refractory to antiarrhythmic drugs. A coronary sinus atrial demand pacemaker at 72 beats per minute was implanted. During the subsequent two months, the patient quickly terminated nine episodes of SVT by activating the generator with an external magnet and competitively pacing the atrium. The second patient had frequent daily episodes of SVT and secondary angina despite vigorous antiarrhythmic medication. Demand ventricular pacing at a rate of 88 beats per minute prevented the recurrence of SVT during the seven month follow-up. A third patient with an old myocardial infarction had frequent biweekly episodes of ventricular tachycardia (VT) refractory to conventional treatment. A ventricular demand pacemaker was implanted, and three episodes of VT were terminated by magnetically activated competitive ventricular pacing at 64 beats per minute. Augmentation of the demand pacemaker rate to 86 beats per minute inhibited the recurrence of VT during a five month follow-up. The rates of the tachycardias were less than 160 beats per minute in all three cases, and evidence suggests a re-entrant or reciprocating mechanism for the tachyarrhythmias. The electrophysiologic rationale for pacemaker therapy in certain types of recurrent SVT and VT is discussed.