Understanding hypertension. The contribution of direct ambulatory blood pressure monitoring

Summary

The description of a fundamental rhythm of circadian variation of blood pressure which is dependant for its expression upon the alpha adrenoreceptor in the peripheral arteriole presents an entirely different way of looking at blood pressure and it is apparent that the effects of drugs which are used to control hypertension upon this rhythm may well be of fundamental importance. The description of this rhythm would not have been possible without the technique of ambulatory intra-arterial blood pressure recording, and there is every possibility that more fundimental discoveries will follow. The abnormality which underlies essential hypertension has yet to be elucidated; these sudies suggest that the abnormality lies in the central nervous system. If it is a primary autonomic defect, then we must look to the hypothalamus rather than the smooth muscle of the peripheral arteriole, the kidney, or genetically — controlled abnormalities of the sodium pump for the “cause” of essential hypertension.

Whatever its mechanism, this rhythm quite clearly presents a much more acceptable method for examining the effects of drugs on blood pressure than taking one-off casual recordings in an out-patient clinic. In particular, the introduction of a time element is bound to provide information missing from conventional clinical trials.