Contribution of cardiac output to renovascular hypertension in man. Relation to surgical treatment

Although cardiac output was on the average higher (P <0.001) in patients with renal arterial disease (42 patients) than in those with essential hypertension (88 patients), levels varied widely within the 2 groups. To determine the possible role of cardiac output variations in the hypertension associated with renovascular lesions, 2 studies were undertaken: (1) Preoperative hemodynamic indexes were studied in relation to arterial pressure response to surgical treatment of the renovascular lesion (12 patients). After anatomically successful surgery (nephrectomy or arterial repair), blood pressure was substantially reduced in 6 patients, and in 5 of the 6 the reduction was associated with a decrease in peripheral resistance. In the other 6 with persistent postoperative hypertension, hemodynamic changes were mixed. Response to surgery was not related to preoperative levels of cardiac output. (2) Correlations between cardiac output and arterial pressure were examined in hypertensive patients of the same age group, 67 with essential hypertension and 35 with renal arterial disease. Among patients with essential hypertension, arterial pressure correlated significantly only with peripheral resistance (r = 0.596, P < 0.001); in contrast, arterial pressure in patients with renovascular hypertension correlated with both cardiac index and total peripheral resistance (P <0.025 and <0.05, respectively). Along with increased output, patients with renal arterial disease also had increased total peripheral resistance (P < 0.001). Thus, although increased cardiac output is a frequent finding in, and possibly a contributor to, renovascular hypertension, it does not appear to be the major factor responsible for its maintenance.