[Variability of blood pressure and baroreceptor function; clinical and scientific relevance].

The human arterial blood pressure shows not only exogenic alterations, but also spontaneous fluctuations. This blood pressure variability has both scientific and clinical relevance. A well-known phenomenon is the so-called "white coat hypertension" which may severely affect diagnosis and therapy of essential hypertension. Furthermore, several studies have provided evidence that the degree of end-organ damage in hypertensive patients is closely related to the circadian blood pressure variability. Therefore, it is tempting to suggest that an optimal antihypertensive treatment should take an improvement of the blood pressure variability into consideration. Among other mechanisms modulating the arterial blood pressure, the baroreflex function has to be mentioned. Diseases like chronic renal failure, treatment with drugs like ciclosporine A and also smoking have been shown to reduce the baroreflex sensitivity. As the baroreflex sensitivity mainly reflects interactions between the blood pressure variability on the one hand and the heart rate variability on the other hand, it is not surprising that also a reduced baroreflex function is an independent cardiovascular risk factor.