Treatment of essential hypertension does not normalize capillary rarefaction.

Objectives: To determine if capillary rarefaction persists when hypertension is treated with angiotensin converting enzyme inhibitor, thiazidic diuretic and/or beta-blocker, and to identify which microcirculatory alterations (structural and functional) persist after anti-hypertensive treatment.

Methods: We evaluated 28 well-controlled essential hypertensive patients and 19 normotensive subjects. Nailfold videocapillaroscopy examination of the fourth finger of the left hand was used to determine the functional capillary densities at baseline, during post-occlusive hyperemia, and after venous congestion. Capillary loop diameters (afferent, apical and efferent) and red blood cell velocity were also quantified.

Results: Compared with normotensive subjects, hypertensive patients showed lower mean functional capillary density at baseline (25.1 +/- 1.4 vs. 33.9 +/- 1.9 cap/mm(2), p<0.01), during post-occlusive reactive hyperemia (29.3 +/- 1.9 vs. 38.2 +/- 2.2 cap/mm(2), p<0.01) and during venous congestion responses (31.4 +/- 1.9 vs. 41.1 +/- 2.3 cap/mm(2), p<0.01). Based on the density during venous congestion, the estimated structural capillary deficit was 25.1%. Mean capillary diameters were not different at the three local points, but red blood cell velocity at baseline was significantly lower in the hypertensive group (0.98 +/- 0.05 vs. 1.17 +/- 0.04 mm/s, p<0.05).

Conclusions: Patients treated for essential hypertension showed microvascular rarefaction, regardless of the type of therapy used. In addition, the reduced red blood cell velocity associated with capillary rarefaction might reflect the increased systemic vascular resistance, which is a hallmark of hypertension.