Evaluation of a catheter technique for ablation of accessory pathways near the coronary sinus using a canine model

The production of atrioventricular block by intracardiac discharges at up to 300 W-sec delivered through standard electrophysiologic catheters is a safe and effective treatment for some patients with supraventricular tachycardias. We evaluated the possibility that a similar technique using a catheter in the coronary sinus might be useful in ablating left-sided bypass tracts associated with the Wolff-Parkinson-White syndrome. Acute studies involved one discharge of 35-45 J in the coronary sinus of five dogs; a sixth dog served as a control. These dogs were killed after 6 hours of observation, during which they remained stable. Two and three discharges of 240 J were used in two dogs and caused profound local damage, including exsanguinating hemorrhage in one. Chronic experiments also were conducted. Sixteen dogs received one to four 35-45 J discharges in the middle coronary sinus and two dogs received four 240-J discharges near the ostium of the coronary sinus. One dog suffered a small perforation of the coronary sinus; there was no significant hemorrhage, and the perforation was promptly sealed by thrombus formation. There were no clinical complications. All dogs recovered uneventfully and regained their usual vigor. Before sacrifice 2-11 weeks later, cardiac catheterization, including coronary arteriography, biplane left ventricular angiography and pressure measurements, was performed; the results were normal in each dog. Gross and microscopic examination revealed fibrosis in the atrioventricular sulcus and atrial wall, and preservation of normal coronary anatomy in all but three dogs. The extent and distribution of the fibrosis suggested the possibility of adapting this technique for the ablation of left-sided bypass tracts in patients with Wolff-Parkinson-White syndrome.