Warm Versus Cold Heart Surgery in Diabetics

The aim of the study was to compare the effect of the classic hypothermic perfusion technique with cold crystalloid cardioplegia with the more modern warm heart surgery with warm continuous cardioplegia in a specific risk group, i.e. diabetics. Retrospective study, built around a date (May, 1993) when the technique was uniformly adopted as standard practice in a cardiac surgical unit (Hamilton), at the time a three specialist cardiac surgical unit in a 600-bed central, university-affiliated hospital in Hamilton, New Zealand. Other changes of practice at the time (team, assistance, learning curve, anaesthesia, perfusion, oxygenators) were carefully analysed. No obvious relevant changes were identified in a rigorous analysis. 2198 operations were analysed and 186 consecutive operations on diabetic patients identified. Normothermic (Group W) coronary bypass operations in 117 diabetic patients were compared to 69 similar operations with hypothermia and antegrade crystalloid cardioplegia (Group C). The groups did not differ with regard to age, sex, severity of diabetes or coronary heart disease. There were more urgent operations in Group W (41 vs. 33%). In Group C, mortality was 5.8%, in Group C 2.6%. Stroke rate was 1.4% in Group C and 1.7% in Group W. There were no differences in perioperative myocardial infections. Inotropes were needed less frequently in Group W (13.9 vs. 30.4%, p<0.05). Atrial fibrillation was more common in Group W (43,9 vs. 31.9%, p<0.05). Heart block was less common in Group W (3.4 vs. 23.2%, p<0.05). Transient renal function impairment was significantly more common in Group W (12.8 vs. 4.3%, p<0.05). More sternal wound problems were seen after hypothermic surgery (14.5 vs. 5.1%). Warm heart surgery seemed safe, with reduced use of inotropic agents postoperatively, less heart block and fewer infections. However, atrial fibrillation was more common and renal impairment may present a problem in a high-risk population.