SYSTEMIC HYPERTENSION FOLLOWING MYOCARDIAL REVASCULARIZATION - METHOD OF TREATMENT USING EPIDURAL ANESTHESIA

Abstract

Seven of 12 patients (58%) undergoing myocardial revascularization surgery became hypertensive in the immediate postoperative period. The hypertensive patients had significant elevations in peripheral vascular resistance (22.0 .+-. 2.0 SE resistance units) compared to measurements in normotensive patients (15.6 .+-. 1.3 SE resistance units) P < 0.05), whereas the heart rates and cardiac indices were similar. Administration of thoracic epidural anesthesia to postoperatively hypertensive patients lowered systemic arterial pressure by decreasing peripheral vascular resistance (P < 0.006) but not affecting the pulse rate and cardiac index. The ratio diastolic pressure-time index/systemic pressure-time index (DPTI/SPTI), an indirect measurement of subendocardial oxygenation, increased from preanesthetic values of 0.80 .+-. 0.08 SE to 1.09 .+-. 0.09 SE (P < 0.025) after the systemic arterial pressure was lowered in postoperatively hypertensive patients. Hypertensive episodes following myocardial revascularization procedures appear related to increased .alpha.-adrenergic activity, which produces elevations in peripheral vascular resistance. Decreasing peripheral vascular resistance by chemical sympathectomy with thoracic epidural anesthesia lowers the systemic arterial pressure and improves the DPTI/SPTI ratio.