The adverse effect of systemic hypertension following myocardial reperfusion.
Transient myocardial ischemia in postoperative hypertension is relatively common with coronary artery bypass surgery. This study examines the effect of hypertension during reperfusion of transiently ischemic myocardium. The animal model was open chest pigs with myocardial ischemia induced by the occlusion of the left anterior descending coronary artery for 30 min followed by 2 hr of reperfusion. A normotensive control group was compared with animals rendered hypertensive with phenylephrine during the ischemic and reperfusion times. In the hypertensive group, systolic blood pressure was raised from 106 to 161 mm Hg and peripheral vascular resistance from normal to 3600 dyn-sec-cm-5. Regional left ventricular wall thickness, mitochondrial function, sarcoplasmic reticulum Ca2+ uptake, tissue calcium, water content, and hemorrhage were evaluated. Compared to controls the hypertensive group had (1) loss of systolic wall thickening with increased diastolic wall thickness in the reperfused zone, (2) intramyocardial hemorrhage in the area of reperfusion, (3) significant impairment of oxidative  phosphorylation by mitochondria isolated from the reperfused zone, (4) a marked reduction in the rate of Ca2+ uptake by sarcoplasmic reticulum vesicles, and (5) an increase in ischemic tissue calcium. Thus, hypertension associated with revascularization of acutely ischemic myocardium may accentuate myocardial damage.
D000818:Animals; D002118:Calcium / Q000032:analysis; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D003331:Coronary Vessels; D004452:Echocardiography; D005260:Female; D006321:Heart / Q000503:physiopathology*; D006439:Hemodynamics; D006973:Hypertension / Q000150:complications*; D007511:Ischemia / Q000209:etiology*; D008297:Male; D008929:Mitochondria, Heart / Q000502:physiology; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D010085:Oxidative Phosphorylation; D012519:Sarcoplasmic Reticulum / Q000502:physiology; D013552:Swine
D002118:Calcium