Effects of inhibitors of angiotensin-converting enzyme on regional hemodynamics

Inhibitors of angiotensin-converting enzyme (ACE) exert favorable regional hemodynamic effects at various sites. In patients with essential hypertension, ACE inhibitors reduce renal vascular resistance while enhancing renal blood flow, glomerular filtration rate, and acute and sustained natriuresis. Whereas these agents may either reduce or have no effect on hepatic blood flow, they are associated with reduced splanchnic resistance. ACE inhibitors reduce total peripheral resistance and may maintain limb blood flow. In normal subjects, they augment blood flow to skeletal muscle and skin and reduce peripheral resistance in vessels supplying these regions. ACE inhibitors appear to exert a vasodilatory effect on large arteries as well as arterioles. Dilatation is often accompanied by significant improvements in arterial compliance, possibly due to direct effects of the renin—angiotensin system on the arterial wall. Reduction of blood pressure is generally not accompanied by reduced cerebral blood flow. Enhanced tissue effects of newer ACE inhibitors such as quinapril may result in improved regional hemodynamic effects.