Ageing and wave reflection

Abstract

To determine the effects of wave reflection on the increase in arterial pressure that occurs with age and its association with concomitant changes in both the magnitude and contour of the arterial pressure pulse. While age-related changes in mean pressure are similar in central and peripheral arteries, changes in pulse pressure and pulse waveform features are different. Because of the specific architectural, geometrical and elastic properties of the arterial vasculature, wave reflection plays an important role in determining peak pressure, the value usually specified as systolic pressure. While the late systolic increase usually determines peak systolic pressure in the central aorta, it is not necessarily related to the peak pressure in the periphery. Peak pressure depends on the timing and intensity of wave reflection, which is a function of the state of the peripheral microvasculature and the elastic properties of the large conduit arteries. Ageing causes changes in both the terminal and central vasculature, so that the intensity of the wave reflection and the transmission properties of arteries affect the arterial pulse to different degrees. Therefore, age-related changes that are observed in the central pressure pulse are different from those observed in the pulse when measured in a limb. Thus the contribution of wave reflection to the determination of peak arterial pressure is not the same at all locations. These findings have profound implications for therapeutic strategies aimed at altering systolic pressure and for a proper assessment of the alteration in cardiac load that occurs with age or with antihypertensive therapy, when measurements are taken in a limb.