INTRAATRIAL DEFIBRILLATION OF HUMAN ATRIAL-FIBRILLATION

Intra-Atrial Defibrillation. Low-energy intra-atrial defibrillation is a new therapeutic option for restoring sinus rhythm in patients with atrial fibrillation (AF), The success rate is quite high when right at rium-coronary sinus or right atrium-pulmonary artery electrode configu rations are used, although the former is associated with a slightly lo wer defibrillation threshold. Several issues regarding the safety and tolerability of the procedure remain unresolved. Our experience and th at of others indicate that low-energy intra-atrial cardioversion is sa fe even during exercise, provided the shock is well synchronized with the QRS and the preshock RR interval is > 500 msec. Reported defibrill ation thresholds in patients with persistent AF range from 4 to 8 J, a nd shocks of this type inevitably are associated with some degree of d iscomfort. Measures aimed at lowering the defibrillation threshold (e, g,, use of biphasic waveforms, antiarrhythmic pretreatment, and use of a single effective shock, as opposed to the multiple shocks delivered in research settings) can be expected to increase patient tolerance a nd extend the indications for low-energy intra-atrial cardioversion, T he procedure currently is indicated for patients with persistent AF wh o are resistant to external defibrillation unable or unwilling to unde rgo general anesthesia. The procedure could be expanded to patients af fected by obesity in whom the efficacy of external cardioversion is lo wer.