Catheter ablation of atrioatrial conduction as cure for atrial arrhythmi after orthotopic heart transplantation

Objectives. We present three patients in whom atrial arrhythmi was treated by ablation of electrical conduction across surgical suture line. Background. Conduction across the suture line separating the donor and native right atri has recently been described after orthotopic heart transplantation. Methods. Mapping and pacing of both grafted and recipient right atrium was performed to assess the relation between both atri and its relevance to clinical arrhythmia, prior to successful radiofrequency at the site of electrical communication. Results. In cases 1 and 3, atrioatrial conduction was bidirectional. In both, two types of P waves were observed during sinus rhythm. In case 2, conduction from the recipient to the grafted atrium yielded very particular surface ECG pattern of atrial extrasystole. The block being unidirectional, the recipient atrial sinus rhythm was not perturbed and behaved like an atrial parasystole. Ablation was performed during sinus rhythm in case 1, recipient right atrial pacing in case 2 and grafted right atrial pacing in case 3 at the site with the shortest conduction time to the other tissue. At the successful ablation site multiple component potentials were recorded. Respectively, 1, 4 and 2 radiofrequency pulses were followed by total atrioatrial conduction interruption. No tachycardi could be induced at the end of the procedure and late follow-up was event free. Conclusions. The existence of arrhythmogenic atrioatrial conduction should be taken into account when evaluating atrial arrhythmias in the transplanted heart because it is potentially curable by radiofrequency catheter ablation.