Basic concepts for the understanding of large arteries in hypertension.

The conventional approach to hypertension considers only the peak and trough of the pressure wave in the brachial artery (systolic and diastolic pressure). An alternate (or supplementary) approach considers mean pressure and fluctuation around this mean. Such an approach permits separation of pulsatile phenomena from steady flow phenomena; it is the basis for description of hydraulic load as vascular impedance and for application of engineering principles to the study of fatigue and degeneration of arteries; it readily explains disturbed arterial function in hypertension in terms of increased peripheral resistance and of increased arterial stiffness. The major effects of hypertension on pressure wave contour, on arterial degeneration, and on left ventricular load are consequences of arterial stiffening rather than of increased resistance. Logical therapy for hypertension should include measures to increase arterial distensibility as well as those to decrease peripheral resistance.