When and how to shunt the coronary circulation in off-pump coronary artery bypass grafting

Abstract

To assess the sequelae of temporary coronary artery occlusion in off-pump, beating heart CABG, i.e. ischemia, hemodynamic instability and the need for conversion to cardiopulmonary bypass. In 200 patients (150 male), mean age 60 (range 35-81) years, 365 distal anastomoses were performed, i.e. 1.8 anastomoses per patient through limited and full access. One hundred seventy six LAD, 61 diagonal, 71 RCA, 7 RPD and 50 circumflex branches were grafted. Patients were pretreated with calcium antagonists, long-acting beta-blockade and had thoracic epidural blockade. The anastomosis was constructed using two microvascular clamps, preceded by ischemic preconditioning in non-occlusive disease. Myocardial ischemia was defined as > 1 mm S-T segment elevation. A simple aorto-coronary shunt, consisting of two intravenous catheters and a 10 cm connecting tube (flow > 20 ml/min), was used in critical ischemia. Ischemia occurred during 35 (10%) temporary coronary artery occlusions. Fifteen of these (43%) were RCA. In five of these 15 patients, all with non-occlusive disease, critical ischemia occurred with bradycardia, third-degree heart block and subsequently severe hypotension, which normally requires conversion to cardio-pulmonary bypass. Following introduction of the shunt (4 patients) electrocardiographic and hemodynamic parameters normalized within 30 s. The off-pump procedures could be continued uneventfully. There were no peri-operative infarctions. Temporary segmental occlusion is an effective method for anastomosis suturing in off-pump, beating heart CABG. Critical ischemia was observed rarely, only in the RCA and in non-occlusive disease. Temporary aorto-coronary shunting could avoid conversion to cardiopulmonary bypass and myocardial infarction.