Circulatory changes in muscle and skin arteries in primary hypertension

This review deals with circulatory adjustments occurring in the limb arteries of hypertensive patients. Measurements of regional blood flow are mandatory, because conclusions drawn from calculated total peripheral resistance often are not applicable to local vascular beds. Limb arteries, which can be followed by easy and noninvasive methods, often are the first choice for study of regional circulation. In this discussion, a few historic studies are cited first; next, the data available on skeletal muscle (forearm and calf) and skin (finger) circulation are reviewed, to show that flow through both muscle and skin is increased in mild and moderate hypertension, while there is a trend to lower values in more severe hypertension. Our own data are derived from 51 untreated patients showing mild to moderate hypertension, matched to 23 normotensive subjects. Flow is measured simultaneously with an ECG-triggered venous occlusion plethysmograph at calf and finger. At rest, calf and finger blood flows are significantly higher and calculated resistance is lower in hypertensive subjects; during reactive hyperemia, blood flow remains higher in hypertensive subjects but calculated resistance increases up to values that are higher, compared to normotensive control subjects; these data are compatible with structural changes in the vascular wall.