TY - JOUR T1 - Low energy internal cardioversion of atrial fibrillation resistant to transthoracic shocks. JF - Heart JO - Heart SP - 635 LP - 638 DO - 10.1136/hrt.75.6.635 VL - 75 IS - 6 AU - S. M. Sopher AU - F. D. Murgatroyd AU - A. K. Slade AU - I. Blankoff AU - E. Rowland AU - D. E. Ward AU - A. J. Camm Y1 - 1996/06/01 UR - http://heart.bmj.com/content/75/6/635.abstract N2 - OBJECTIVE: To investigate the efficacy of internal cardioversion using low energy shocks delivered with a biatrial electrode configuration in chronic atrial fibrillation resistant to transthoracic shocks. METHODS: Low energy internal cardioversion was attempted in 11 patients who had been in atrial fibrillation for 233 (SD 193) days and had failed to cardiovert with transthoracic shocks of 360 J in both apex-base and anterior-posterior positions. Synchronised biphasic shocks of up to 400 V (approximately 6 J) were delivered, usually with intravenous sedation only, between high surface area electrodes in the right atrium and the left atrium (coronary sinus in nine, left pulmonary artery in one, left atrium via patent foramen ovale in one). RESULTS: Sinus rhythm was restored in 8/11 patients. The mean leading edge voltage of successful shocks was 363 (46) V [4.9 (1.2) J]. Higher energy shocks induced transient bradycardia [time to first R wave 1955 (218) ms]. No proarrhythmia or other acute complications were observed. CONCLUSIONS: Low energy internal cardioversion of atrial fibrillation can restore sinus rhythm in patients in whom conventional transthoracic shocks have failed. ER -