Increased Skin Capillary Density in Treated Essential Hypertensive Patients

Background Microvascular rarefaction is a hallmark of essential hypertension. We measured the skin capillary density in nondiabetic hypertensive subjects with effective antihypertensive treatment and evaluated possible correlations with arterial blood pressure (BP). Methods This cross-sectional observational study included 76 (55 ± 1 years) consecutive outpatients with essential hypertension under chronic antihypertensive drug treatment (BP < 140/90 mm Hg), 24 age- and sex-matched patients with recently discovered and never-treated hypertension and 70 normotensive (BP < 140/90 mm Hg) age- and sex-matched healthy controls. We used intravital video-microscopy to measure basal and maximal (during venous congestion) skin capillary densities in the dorsum of the fingers. Aortic stiffness was evaluated using pulse wave velocity and central aortic pressure calculated from radial artery applanation tonometry. Results Baseline and maximal capillary densities (number/mm2) were significantly lower (59.6 ± 2.0 and 62.0 ± 1.9) in untreated than in treated hypertensive patients (74.0 ± 1.4 and 79.4 ± 1.5; P< .001) and than in normotensives (68.2 ± 1.5 and 72.4 ± 1.5; P< .001). Based on multiple regression analysis, after adjustment to tobacco consumption, aortic (and not brachial) systolic BP was inversely correlated with basal and postocclusive capillary densities in normotensive subjects. In hypertensives, this correlation disappears and capillary density was influenced by two independent variables, antihypertensive drug treatment and overweight. Conclusions In nondiabetic hypertensive patients, capillary density is reduced in association with a cluster of cardiovascular risk factors involving tobacco consumption and obesity. The finding of an increased capillary density in effectively treated antihypertensives suggests that a cause-to-effect relationship between BP and capillary density should be evaluated in a long-term prospective follow-up.