A Hemodynamic Comparison of Essential and Renovascular Hypertension

Systemic hemodynamic measurements were obtained in 15 normal subjects and 30 untreated hypertensive patients (15 with essential hypertension and 15 with fibrosing stenosis of renal arteries). The essential hypertensives were selected from a larger group solely on the basis of matching their mean arterial pressures and ages with those of the patients with renal arterial disease in matched pairs; cardiac index was consistently higher in patients with renovascular hypertension than in those with essential hypertension. The higher cardiac output was maintained in the group with renal arterial disease even when reduced by tilting the subjects to a 50° head-up position. Total peripheral resistance was increased in both hypertensive groups. The low cardiac indices and mean rates of left ventricular ejection found in essential hypertension may also implicate the heart in this form of hypertension. Hence, increased total peripheral resistance, long thought to be the hemodynamic hallmark of hypertension, may not be the sole systemic abnormality; cardiac output may be increased in renal arterial disease and even reduced in essential hypertension.