Small artery structure adapts to vasodilatation rather than to blood pressure during antihypertensive treatment

Correction of the abnormal structure of resistance arteries in essential hypertension may be an important treatment goal in addition to blood pressure (BP) reduction. We investigated how this may be achieved in a prospective clinical study.

Plethysmography was used to measure forearm resting vascular resistance (Rrest) and minimum vascular resistance (Rmin) as a measure of vascular structure. Two different groups of patients with essential hypertension were examined at baseline and after 6 months of antihypertensive treatment. In group A, 21 patients with never-treated essential hypertension were treated by their general practitioners using a variety of drugs to allow an assessment of the drug-independent effects. In group B, 28 beta-blocker-treated patients were shifted to angiotensin II receptor blocker treatment (eprosartan) to allow vasodilatation with no change in BP.

In group A, mean ambulatory blood pressure (ABP) fell from 119 +/- 2 (SE) to 103 +/- 2 mmHg (P < 0.01), whereas mean ABP was unchanged in group B (100 +/- 1 to 99 +/- 1 mmHg, P = NS). Both groups showed similar reductions in Rrest (-33.4 and -28.5%, respectively) and in Rmin (-15.4 and -15.6%, respectively). There was a strong correlation between changes in Rrest and Rmin within both groups (r = 0.57, P < 0.01 and r = 0.68, P < 0.0001, respectively), whereas the change in BP in group A was not correlated to the change in Rmin (r = -0.03).

The correction of forearm resistance artery structure during antihypertensive treatment depends on the vasodilatation achieved rather than BP reduction.