Recurrent supraventricular tachycardia. Success and subsequent failure of termination by implanted endocardial pacemaker.

After repeatedly establishing the efficacy of competitive premature atrial and ventricular stimuli in terminating supraventricular tachycardia (SVT) in a patient with recurrent and refractory SVT, a permanent right ventricular endocardial demand generator set at 81 beats per minute was implanted. During the subsequent months, many tachycardic episodes, ranging between 160 to 185 beats per minute, were promptly terminated by activating the pacemaker unit with an external magnet and competitively pacing the right ventricle. However, 16 months after implantation, magnetically induced ventricular capture failed to control the SVT. Magnetically induced competitive pacing in SVT should be reserved for the most intractable and refractory cases.