REGIONAL AND TRANSMURAL MYOCARDIAL TEMPERATURE DISTRIBUTION IN COLD CHEMICAL CARDIOPLEGIA - SIGNIFICANCE OF CRITICAL CORONARY ARTERIAL-STENOSIS

  • 1 January 1981
    • journal article
    • research article
    • Vol. 81  (6) , 851-859
Abstract
There is a growing recognition of discrepancies in myocardial temperatures during cold chemical cardioplegia. This study was designed to determine the extent to which coronary arterial stenosis sufficient to abolish vasodilatory reserve in the working heart, but still compatible with myocardial viability (critical stenosis), limits heat transfer from the heart during cardioplegic infusion compared to complete coronary occlusion and no stenosis (control). In 9 dogs temperatures were measured from the subepicardium, midwall and subendocardium of the left ventricle in the distributions of the circumflex (CCA) and left anterior descending (LAD) coronary arteries plus the aortic root, septum, mediastinum and ventricular cavities. Cardiopulmonary bypass was instituted with core cooling to 28.degree. C. Three infusions of cold (4.degree. C), radioactive microsphere-labeled, KCl arresting solution were administered with no stenosis, CCA critical stenosis and CCA occlusion, with intervening periods of reperfusion. The data (mean .+-. standard error of the mean) indicate that myocardial cooling was transmurally uniform under all conditions, but was significantly impaired (P < 0.01) in the CCA region by critical stenosis (17.4.degree. .+-. 1.2.degree. C) and occlusion (23.6.degree. .+-. 0.4.degree. C) compared to control (8.3.degree. .+-. 0.5.degree. C), because of reduced perfusate flow to regional tissues (r = 0.62, P < 0.001). Coronary artery lesions, including those compatible with myocardial viability, impose a severe constraint on myocardial heat transfer and point to a need for improved cardioplegic technique.