FEASIBILITY OF RADIOFREQUENCY POWERED, THERMAL BALLOON ABLATION OF ATRIOVENTRICULAR BYPASS TRACTS VIA THE CORONARY SINUS - IN-VIVO CANINE STUDIES

Radiofrequency catheter ablation of left-sided accessory pathways is t echnically demanding and usually requires left heart catheterization. The feasibility of creating lesions from within the coronary sinus of sufficient size to ablate accessory pathways in humans using a thermal balloon catheter was studied in 20 dogs. in group 1 (n = 14), 17 ther mal inflations were performed in 12 dogs at either 70 degrees, 80 degr ees or 90 degrees C each for 30 or 60 seconds (in 2 dogs two non-therm al control inflations were performed). Animals were sacrificed 6.3 +/- 2.6 days later. In group 2 (n = 6), seven thermal inflations were per formed at 90 degrees C each for 180, 300, or 360 seconds. Group 2 anim als received antiplatelet and anticoagulant therapy for 1 week and wer e sacrificed at 13 +/- 10.7 days. In both groups, hemodynamic, angiogr aphic, and electrocardiographic studies were performed at baseline, 1 hour after inflation, and prior to sacrifice. All dogs remained clinic ally stable throughout the procedure and no complications were attribu ted to the effect of thermal inflation. Thermal lesions measured 14.4 +/- 4.4 mm in length and extended from the coronary sinus intima to a mean depth of 2.9 +/- 1.2 mm (range 1.4-6.5 mm). Group 2 lesions were significantly deeper than group 1 lesions (P = 0.03). Of the 24 therma l lesions creased, atrial necrosis was present in 23 and ventricular n ecrosis in 11. In all lesions there was some degree of either atrial n ecrosis, ventricular necrosis, or both. A variable degree of coronary sinus thrombus was present in 18 dogs without clinical sequelae. If is concluded that radiofrequency balloon heating via the coronary sinus can create thermal lesions in she atrioventricular sulcus of dogs that may be of sufficient size to ablate accessory left-sided pathways in humans.