The nature of a microcirculatory change in hypertensive patients during increased blood pressure

Abstract

Aim. To evaluate changes in the microcirculation (MC) of hypertensive patients during increased blood pressure (BP). Subjects and methods. The investigation enrolled 66 patients with grades 2-3 hypertension and 57 apparently healthy individuals. After 2-day discontinuation of antihypertensive drugs, the patients were divided into 2 groups: 1) BP ≤140/90 mm Hg; 2) BP ≥160/100 mm Hg. MC was examined by laser Doppler flowmetry. Results. In the hypertensive patients, the episodes of higher BP are accompanied by the constriction of meta-arterioles and precapillaries, resulting in diminished capillary blood flow. A compensatory increase in pulse blood filling is attended by accelerated blood flow with decreased vessel diameters and increased shear stress. This creates conditions for the endothelial release of vasodilator mediators. However, the limited reserves of an endothelial relaxing effect are not enough to normalize BP. This resultant increase in tissue hemoperfusion is nonproductive since it is due to intensified shunt blood flow and venous plethora. Conclusion. Severe MC disorders in hypertensive patients with increased BP are characterized by incompetent compensatory mechanisms, reduced endothelial relaxing potential, and depressed capillary tissue diffusion. It may be believed that these disorders appreciably determine target organ involvements in hypertension.

Keywords

• microcirculation
• hypertension