Ventricular Fibrillation Without Hemodynamic Deterioration: An Electrocardiographic Paradox Explained by Heterotopic...

Heterotopic heart transplantation (HHT) is rarely performed in contemporary practice and poses distinct electrophysiological challenges due to the coexistence of the patient's native heart and the transplanted donor organ.

We present the case of a 56-year-old man who experienced recurrent ventricular arrhythmias 6 years post-HHT. The patient initially presented with a syncope and ventricular tachyarrhythmia originating from the donor heart while the native heart maintained sinus rhythm. The arrhythmogenic substrate was attributed to transplant vasculopathy in the donor heart. Management required implantable cardioverter-defibrillator placement and antiarrhythmic therapy.

This case demonstrates the fundamental electrophysiological principle that simultaneous documentation of 2 different cardiac rhythms necessitates the presence of 2 independent cardiac rhythms. Although HHT is now rarely performed, this case provides insights into the cardiac electrophysiology and management of dual arrhythmogenic substrates.

Two simultaneously detectable rhythms in the surface electrocardiogram provide compelling evidence of the presence of 2 independent cardiac excitation systems. Even a dysfunctional native heart may maintain consciousness during sustained polymorphic ventricular tachycardia of the donor heart through parallel circulation over a limited period of some hours.