Essential hypertension: hemodynamic and therapeutic changes over 20 years.

The hemodynamic disturbances in essential hypertension depend on the age of the subjects and the severity of the hypertensive state. In a 20-year follow-up study, we demonstrated a shift in the hemodynamic characteristics from a high output/normal resistance pattern in the early phase toward a low-flow/high-resistance pattern in the later period. The arteriovenous oxygen difference increased, particularly during exercise, and the oxygen reserve in venous blood decreased. Treatment with conventional drugs (beta-blockers and/or diuretics) for 20 years with satisfactory control of diastolic blood pressure did not prevent a marked increase in total peripheral resistance and a reduction in stroke index and cardiac index. In recent years, beta-blockers with vasodilating activity have been introduced in the treatment of hypertension (labetalol, acebutolol, dilevalol, celiprolol, and carvedilol). The hemodynamic effects of these compounds clearly differ from the changes induced during acute and chronic conventional beta-blocking treatment. In contrast to the usual beta-blockers, these drugs reduce total peripheral resistance acutely, and reduce cardiac index considerably less; arteriovenous oxygen difference is more normal. In an acute study of carvedilol in 18 patients with essential hypertension, total peripheral resistance was reduced 8% at rest (supine) and 6% during exercise. Exercise heart rate was reduced 12%, but due to an increase in stroke index, the reduction in cardiac index was only 6%-considerably less than what is seen during treatment with conventional beta-blockers.