Resynchronization Therapy During Sustained Ventricular Tachycardia

Abstract

A 62-year-old gentleman with a history of an ischemic cardiomyopathy and previous implantation of a biventricular cardioverter-defibrillator presented with complaints of palpitations and a wide complex ventricular paced rhythm at 120 bpm. This was originally thought to be ventricular tracking of an atrial tachycardia at the upper tracking rate, as the patient remained hemodynamically stable for three consecutive days in this rhythm. On the third day, the patient's implantable cardioverter-defibrillator (ICD) was interrogated and it was found that he was indeed in a sustained ventricular tachycardia with biventricular pacing being delivered as a function of the ventricular sense response feature. When this feature was turned off, the patient immediately deteriorated hemodynamically and required a commanded shock through the ICD to terminate the tachycardia. This is an extremely rare presentation of this pacing feature found in biventricular ICDs, which in this case provided significant hemodynamic benefit during a malignant arrhythmia.

Keywords: Biventricular implantable cardioverter-defibrillator; resynchronization therapy; ventricular sense response; ventricular tachycardia.

Figure 1:

A 12-lead electrocardiogram that demonstrates a wide complex rhythm with pacemaker spikes preceding QRS complexes. The ventricular rate is approximately 440 ms (125 bpm).

Figure 2:

Intracardiac markers from the patient with the presenting arrhythmia’s implantable cardioverter-defibrillator demonstrate an ongoing ventricular sensed rhythm at a cycle length of 490–560 ms with atrioventricular dissociation and biventricular pacing on sensed beats. An atrial tachycardia at a cycle length of 500 msec is also evident. Markers are suggestive of a ventricular sense response algorithm. Ab = atrial blanking; as = atrial sensing; TS = ventricular tachycardia sense; BVS = biventricular pacing on a ventricular sensed beat.

Figure 3:

A 12-lead electrocardiogram with inhibition of pacing that demonstrates an underlying ventricular tachycardia at a cycle length of 540 ms (112 bpm) of a right bundle branch, left superior axis morphology.