Systemic hypertension following myocardial revascularization

Abstract

Systemic hypertension was noted to be particularly frequent in the immediate postoperative period following myocardial revascularization procedures. A sustained increase in diastolic pressure to 100 mm. Hg or more occurred in 29 of 80 preoperatively normotensive patients (36 per cent); of 22 patients who were hypertensive before surgery, 5 (23 per cent) had pressure rises of 30 mm. Hg or more above their preoperative levels. Thus, of 102 patients undergoing aortocoronary bypass or internal mammary artery implant, 34 or one third had a hypertensive episode following surgery. There was no significant difference between the two procedures in the incidence of postoperative hypertension (35.5 per cent and 26.9 per cent, respectively, p > 0.10). In contrast, similar episodes were significantly less common following other types of surgery, occurring in only 4 of 107 patients after major noncardiac operations (p < 0.001) and in 2 out of 38 (5 per cent) following cardiac valve replacement (p < 0.005). This difference was not related to anesthetic agents used, to cardiopulmonary bypass, or to preoperative blood pressure levels. The postoperative rise in pressure was not associated with increase in central venous or left atrial pressures or with signs of hypervolemia or of renal dysfunction. It persisted despite adequate analgesia but was usually controlled by intravenous promazine, although sodium nitroprusside had to be used in a few instances. Its frequency after coronary-arterial surgery, its transient course, and the apparent absence of other causes suggest that this hypertension might be related to some coronary pressor reflexes.