Apparent dual exit pathways during ventricular tachycardia recorded by an ICD.

Ventricular tachycardia (VT) with dual exit pathways has been demonstrated in many ways. In this respect we found suggestive evidence of dual exit behavior during VT in a patient with an implanted cardioverter-defibrillator. The evaluation was done with continuous recordings of the right ventricular (RV) and left ventricular (LV) electrograms. The recordings documented the varying duration of the LV to RV delay and no change in the RV rate during increases in the LV-RV delay. The unchanged rate ruled out RV participation in the VT circuit. This ruled out the presence of VT with dual exit pathways and provided proof of an unusual RV bystander that did not participate in the VT circuit.