Myocardial temperature differences as a guide to the order of coronary artery bypass anastomoses in high-risk patients

A technique for increasing the effectiveness of hypothermic, hyperkalemic cardioplegia for myocardial protection during ischemic arrest is described. The essence of the technique is delivery of cold cardioplegic solution directly to areas of the myocardium inadequately perfused through the root of the aorta. The solution is delivered through grafts placed preferentially to the areas identified by temperature measurements as being incompletely cooled. The sequence of all distal anastomoses is determined by the differences in temperature, in order of the warmest to coldest regions. Favorable results were obtained in 200 consecutive high-risk patients through application of this technique. The mortality rate was 3.0 percent. Only three of the six deaths were related to low output failure, and they occurred relatively early in the series. The perioperative myocardial infarction rate was 3.5 percent. No single factor previously reported to increase operative mortality influenced the rate of death or infarction in this series. There were no deaths or infarctions in 41 patients who had only one risk factor. Only when a constellation existed, which consisted of (1) three or more risk factors, (2) the need for extensive surgery (five or more grafts or additional procedures), and (3) advanced age, did the mortality rate approach levels previously reported in patients with any single risk factor. The mortality rate was only 0.76 percent (one death) in 130 patients in this high-risk group in whom surgery was limited, by the extent of disease, to bypass of fewer than five vessels, regardless of age or the number of risk factors.