Arterial compliance in hypertension.

The arterial system has two distinct functions: to deliver an adequate supply of blood to body tissues (conduit function) and to smooth the pulsations resulting from intermittent ventricular ejection. A reduction in lumen diameter leads to an abnormal conduit function and has adverse effects (ischaemia) downstream, whilst stiffening of the vessel wall results in abnormal cushioning function and has adverse effects on the heart (increased ventricular stress and myocardial oxygen consumption). Arterial compliance, which may be evaluated using propagative models of the pulse and pulse wave velocity (PWV), is significantly reduced in hypertensive patients compared with age-matched control subjects. The use of antihypertensive drugs is not always associated with differing effects on arterial compliance. Whereas calcium channel blockers and ACE inhibitors decrease PWV for an equivalent fall in blood pressure, dihydralazine-like drugs are unable to modify PWV. This suggests that effects on the structure and function of the heart and blood vessels are dissociated from blood pressure lowering effects.