Effects of cryothermia during cold cardioplegia on epicardial and intramural coronary arteries

Abstract

Cryosurgery is playing an increasingly important role in the surgical treatment of various supraventricular and ventricular tachyarrhythmias. The short-term and long-term effects of cryogenic injury on epicardial and intramural coronary arteries were studied in 22 dogs. Transmural cryolesions encompassing a posterolateral branch of the circumflex coronary artery were produced in the inferior left ventricular wall during extracorporeal circulation and cold cardioplegic arrest. The mean epicardial cryolesion area ± standard deviation was 10.4 ± 1.8 cm 2. The mean epicardial coronary artery diameter ± standard deviation measured 1.2 ± 0.4 mm. At 6 hours, no important structural changes were noted in any of 6 dogs. At 48 hours, 1 of 2 epicardial coronary arteries showed recent thrombus. At 1, 3, and 6 months, the epicardial coronary arteries were occluded due to thrombosis and intimal hyperplasia in 13 of 14 dogs. A limited degree of recanalization was observed. At all follow-up intervals, the intramural coronary arteries exhibited a histologic pattern similar to that of the epicardial coronary arteries. It is concluded that the exposure of major epicardial coronary arteries to cryoinjury during cold cardioplegic arrest should be avoided where possible.