Systemic hypertension following myocardial revascularization. A method of treatment using epidural anesthesia

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 S.E. resistance units) compared to measurements in normotensive patients (15.6 +/- 1.3 S.E. resistance units) (p less than 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 less than 0.005) 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 S.E. to 1.09 +/- 0.09 S.E. (p less than 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 products elevation 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.