Left hemispheric strokes in coronary surgery: implications for end-hole aortic cannulas

Background. Perioperative stroke (POS) is a devastating complication of coronary artery bypass grafting (CABG). Many studies have been published concerning risk factors and possible causes of POS but none have studied which side of the brain is more frequently involved. The finding of a strong preponderance of left-sided strokes calls into question some widely held theories as to the cause of POS and implicates end-hole aortic perfusion catheters as a major factor. Methods. During a 3-year period (1996 to 1998), prospective data were collected on all 2,217 consecutive CABG patients at one hospital (with surgery by different surgeons in different groups). Strokes were classified as perioperative (within 3 days of surgery) or late (beyond 3 days but during hospitalization). Results. There were a total of 51 strokes (2.3%): 21 left, 10 right, 7 bilateral, 7 lacunar, 1 brainstem, and 5 indeterminate. There were 18 major territorial perioperative strokes on the left side and 6 on the right side. Thus, 75% (18 of 24) of POS were left-sided. Stroke patients were significantly younger than nonstroke patients (66.3 ± 10.52 versus 71.4 ± 8.47 years, p = 0.009). Other demographic data did not differ significantly. Conclusions. If aortic clamping, cannulation, or manipulation were responsible for most strokes, then right-sided strokes should predominate, as the innominate artery is closest to the source of such emboli. In contrast, end-hole aortic cannulas direct a high-velocity jet at the left carotid orifice and may be responsible for a large proportion of POS. Side-hole aortic cannulas may reduce the incidence of this complication.