Risks of cerebrovascular events related to open heart surgery

Prevention of perioperative cerebrovascular injury in patients undergoing open heart surgery is a serious task for the surgeon, especially as age and severity of atherosclerotic disease increases. The most significant predisposing factors have been identified as existing carotid arterial disease or prior stroke, heavy calcification of the aorta, renal dysfunction, advanced age, and diabetes mellitus. We have studied a series of 600 open heart patients from 1992 to 1995 from the incidence of peri-operative stroke and mortality, evaluating 16 risk factors: heavy calcification of the ascending aorta, asymptomatic carotid disease, insulin-dependent diabetes mellitus, prior CVA, left ventricular function (ejection fraction of 20% or less), age greater than 70, renal dysfunction, transmural myocardial infarction, fluid balance index greater than 2500 ccs, smoking, type of procedure, emergency procedure, non-insulin-dependent diabetes mellitus, cardiopulmonary bypass time, gender, and hypertension Stroke occurred in 8 patients (1.3%), one of whom die postoperatively. Full or near-full recovery was experienced by 5 patients; 2 patients remained partially dysfunctional at the end of the study period. The operative mortality was 2.0% (12 patients); 10 deaths occurred in hospital and 2 following discharge within 30 days postoperatively. The risk of stroke was 15 times greater in patients over age 70; 16 times greater in older males (> or = 70 years); 5 times greater in patients with prior stroke or existing (asymptomatic) carotid artery disease; 8 times greater in patients with renal dysfunction; 4 times greater with a positive fluid balance index; and twice greater when cardiopulmonary bypass exceeded 110 minutes. Four of the stroke patients had diabetes mellitus. Two of 9 patients with heavy calcification of the aortic arch suffered cerebrovascular injury. Six or more of the risk factors studied were present in 81 patients; all 8 stroke patients (9.9%) came from this subgroup. The study suggests the importance of pre-operative evaluation of cerebrovascular atherosclerotic disease and the minimal manipulation ("minimal touch" technique) of a calcific aortic arch.