Abstract
The right ventricular moderator band (MB) is increasingly being
recognized as a source for PVCs and PVC-mediated ventricular
fibrillation. Monomorphic PVCs, non-sustained monomorphic VT and
ventricular fibrillation are all documented arrhythmias originating from
the MB. The benign PVCs usually have a coupling interval in excess of
400 msec. When PVCs trigger VF, coupling intervals are typically short,
less than 300 msec.
We report here a case of long-standing frequent monomorphic PVCs with a
coupling interval of > 400 msec from the right ventricular
distal conduction system embedded in the moderator band that progressed
to non-sustained ventricular tachycardia. Following suppression of the
arrhythmia with RF ablation, the arrhythmia recurred with PVCs at a
shorter coupling interval (<300 msec), with frequent
repetitive non-sustained polymorphic VT and triggering of sustained
ventricular fibrillation. The use of a cryoballoon to ablate over the
course of the moderator band resulted in complete and durable
suppression of ventricular arrhythmias.