Catheter ablation of accessory pathways using radiofrequency energy in the canine coronary sinus

Ablation of a left-sided accessory pathway with high energy direct-current shocks delivered by an electrode catheter in the coronary sinus is associated with the risk of coronary sinus rupture. The safety and effectiveness of closed chest catheter desiccation in the coronary sinus with use of radiofrequency energy was studied. Radiofrequency energy (174 +/- 74 J) was applied between the distal electrode of a standard electrode catheter placed 3 to 6 cm inside the coronary sinus and a large posterior chest wall patch in 16 dogs. No arrhythmias or hemodynamic changes were observed. Three dogs were killed approximately 1 h after ablation and 13 after 2 to 4 weeks. Lesions in the atrioventricular (AV) sulcus were observed in 14 of 16 dogs. Lesions were 11.6 +/- 6 mm in length, 4.3 +/- 2.3 mm in width and 2.8 +/- 1.4 mm in depth. Microscopic examination showed well circumscribed areas of necrosis and fibrosis in the fat of the AV sulcus. The media and intima of the circumflex coronary artery were not involved nor was the endocardium or mitral apparatus damaged in any dog. Coronary sinus thrombus was present in 3 of 16 dogs. Large amounts of radiofrequency energy can be safely applied to the coronary sinus. The size and location of the lesions produced suggest that this technique may be useful for the interruption of left-sided accessory AV connections in humans.