ARTERIAL STIFFNESS AND WAVE REFLECTIONS FOLLOWING ACUTE CALCIUM BLOCKADE IN ESSENTIAL-HYPERTENSION

Antihypertensive agents are routinely studied in terms of changes in t he level of systolic, diastolic, and mean arterial pressure. Pulse pre ssure may be independently modified from these parameters as a consequ ence of specific changes in the mechanical properties of the large art eries and in the timing of incident and reflected pressure waves. The aim of this study was to evaluate the changes in pulse pressure produc ed by acute calcium blockade by the dihydropiridine derivative, lacidi pine, in a double-blind design versus placebo in 18 subjects with mild to moderate hypertension. Carotid and femoral pressure waveforms were recorded noninvasively by applanation tonometry using a Millar microm anometer-tipped probe. Early (Pi) and mid-to-late (Ppk) systolic peaks of carotid pressure waveform were evaluated, enabling the effect of i ncident pressure wave to be quantified as the ratio of Pi to the total height of carotid pulse wave (PP) (Pi/PP) and the effect of wave refl ections as the ratio (Ppk - Pi)/PP. Travel time of the reflected wave (Delta tp) was timed from the foot of the pressure wave to the foot of the late systolic peak. Pulsatile changes in diameter were studied us ing noninvasive echo-tracking techniques. Whereas mean arterial pressu re significantly decreased following lacidipine, pulse pressure measur ed at three different sites (brachial, carotid, and femoral arteries) was unchanged. Carotid-femoral pulse wave velocity, carotid and femora l arterial stiffness, and Delta tp were not modified, whereas the (Ppk - Pi)/PP ratio and left ventricular ejection time were significantly reduced and the Pi/PP ratio was significantly increased. The study pro vides evidence that the unchanged pulse pressure following acute calci um blockade involves both an increase in ventricular ejection and inci dent pressure wave and a significant modification in the timing betwee n ventricular ejection and the return of arterial wave reflections. Du ring antihypertensive therapy by acute calcium blockade, unchanged pul se pressure in the presence of reduced mean arterial pressure may cont ribute to maintaining or even increasing the pulsatile component of th e cardiac work in the early phase of treatment.