A CRITICAL-ASSESSMENT OF NEUROLOGICAL RISK DURING WARM HEART-SURGERY

A prospective randomized trial comparing retrograde warm blood cardiop legia with cold oxygenated crystalloid cardioplegia in coronary bypass patients at Emery University revealed an increased risk of adverse ne urological events in the warm group (4.5% vs 1.4%, p < 0.005). Multiva riant analysis found four variables to be independent predictors of ad verse neurological outcome: congestive heart failure (p = 0.002); age (p = 0.002); aortic cross-clamp time (p = 0.02); and randomization to the warm group (p = 0.026). In Toronto, a prospective randomized trial compared antegrade warm blood cardioplegia with antegrade cold blood cardioplegia. Compared to the Emery trial, the Toronto series containe d fewer female patients (16% vs 25%), fewer patients older than age 70 (16% vs 30%), and fewer redo operations (4% vs 14%). The other promin ent differences between the Emery series and the Toronto series were: extensive use of retrograde cardioplegia in the Emery series; mild hyp othermia in the warm group in the Toronto series; and elevated serum g lucose in the warm group in the Emery series. The Toronto series showe d no difference in adverse neurological events comparing cold versus w arm cardioplegia groups. A comparison of these two series suggests tha t mild hypothermia in the Toronto series, elevated glucose in the Emer y series, or the use of retrograde cardioplegia may be operative in th e elevated incidence of adverse neurological events seen in the Emery series in addition to a relatively larger number of highrisk patients (female, elderly, and redo) in the Emery series.