Capillary rarefaction in the forearm skin in essential hypertension

Objective: To determine whether there is a reduction in human forearm skin capillary density in essential hypertension. Subjects and methods: We compared the number of capillary loops in the forearm skin of 12 patients with established, uncomplicated essential hypertension (mean blood pressure 180/109 mmHg) with that in carefully matched control subjects, using intravital capillaroscopy and fluorescein angiography. Results: There was a significant reduction in forearm skin capillary density in the hypertensive patients compared with the normotensive subjects. This represents a reduction by approximately 20% in capillary density. Capillary density was inversely correlated with blood pressure in the hypertensive patients alone (r = -0.4, P< 0.05) and in the whole group. Conclusion: The present study demonstrates a reduction in capillary density in the forearm of patients with essential hypertension. If this rarefaction in the forearm is also present in other vascular beds, it could result in an approximately 20% increase in peripheral resistance, which might play an important additional role in determining blood pressure.