European Journal of Cardio-Thoracic Surgery, Vol 4, 613-617, Copyright © 1990 by European Association for Cardio-thoracic Surgery
Myocardial protection by simple systemic hypothermia without aortic occlusion
AW Susilo, A Rocher, R Mohan and A van der Laarse
Department of Cardiovascular Surgery, St. Jan Hospital, Brugge, Belgium.
Systemic hypothermia at 25 degrees-28 degrees C without chemical
cardioplegia was used in 908 patients undergoing coronary artery bypass
grafting. Local coronary artery flow was interrupted only during grafting
of a distal anastomosis. Systemic perfusion pressure was maintained at
80-100 mmHg, hematocrit at 20%-25%, and pCO2 and pH were monitored during
hypothermia according to the alpha-stat principle, while the left ventricle
was vented routinely. Proximal anastomoses were performed just before
extracorporeal circulation was started by only partially occluding the
ascending aorta. Preoperatively 61.9% of the patients had had a myocardial
infarction, and 44% had unstable angina. In 14% a severe lesion of the main
stem of the left coronary artery was present. Left ventricular function was
moderately depressed in 25% and severely depressed in 8% of the patients.
Forty-eight patients (5.3%) were aged 70 years or older. The mean number of
grafts placed per patient was 3.3. Perioperative myocardial infarction
occurred in 3%. Death due to left ventricular failure occurred in 0.4%. No
left ventricular assist devices were needed; an intra-aortic balloon pump
was used in 1%; positive inotropic support was required in 3.8% of the
patients. These results indicate that systemic hypothermia alone provides
safe myocardial protection and in certain cases may be the method of
choice, particularly if aortic cross clamping or administration of
cardioplegic solution is contraindicated. In addition, this method provides
rapid revascularization of a severely ischemic zone, as present after
unsuccessful PTCA procedures.
