ABPM ALLOWS TO ESTIMATE BLOOD-PRESSURE VARIABILITY

The blood pressure variability is usually given as standard deviation (or ''variance'' resp. ''variation coefficient'') of the systolic and diastolic mean values from different intervals (e.g. daytime, nighttime, 24 hour period). Compared to the superior, but less practical invasive ''beat-to-beat''-recording, giving the ''true'' blood pressure variability, the extend of the every day blood pressure variability may also be estimated by the intermittent ABPM recording, whereby measurements should be undertaken every 15 minutes in daytime and every 30 minutes in nighttime. There is a positive correlation between blood pressure variability and physical resp. mental activity, the wake-sleep-rhythm, the extend of the blood pressure elevation, and the patients age, as well as to concomitant and consecutive diseases in hypertension. Definite upper normal limits do not exist yet; for middle age subjects and an usual every day activity the upper normal limits of the blood pressure variability may be in day time 17 / 13, and 13 / 10 mmHg (syst. / diast.) during the night. Knowing, that arterial hypertension does not only lead to left ventricular hypertrophy, but as well to vascular (media-) thickening, a reduced arterial compliance may be disclosed by a greater blood pressure variability, having possibly prognostic implications. Furthermore, it seems likely, that in future antihypertensive drugs are not only validated by the blood pressure lowering effect, but as well by reducing the blood pressure variability, e.g. as a consequence of the regression of vascular hypertrophy (e.g. with calcium antagonists? ACE-inhibitors?).