[Hypertension and microcirculation]

The importance of the microcirculation (comprising the smallest arteries, arterioles, capillaries and venules) in hypertension and other cardiovascular diseases is well known. The small resistance arteries develop structural changes such as an increase in the wall/lumen ratio and the capillary networks of different vascular beds become rarefied in response to increased blood pressure. These changes not only contribute to hypertensive lesions of target organs but also maintain or amplify the increased blood pressure by increasing peripheral resistances, so creating a vicious circle. Microvascular changes in hypertension may also lead to an increased reflection of the pressure wave towards the heart from the peripheral reflecting sites. This reflected wave also increases systolic blood pressure without increasing the diastolic pressure, thereby increasing the pulse pressure. A high pulse pressure may induce lesions of the vessel walls and of the endothelium of the large arteries, and this is known to be a significant independent risk factor for cardiovascular mortality, especially in the elderly. Microvascular rarefaction could possibly be reversed by therapeutic angiogenesis with cytokines but this treatment is difficult to deliver to the myocardium and is not yet available in clinical practice. Some conventional antihypertensive therapies, including the association of a low dose angiotensin converting enzyme inhibitor, perindopril, and a diuretic, indapamide, may have a beneficial effect on the microcirculation. It has been demonstrated clinically that these drugs specifically reduce the pulse pressure, probably by decreasing the reflected pressure wave, and, therefore, additional benefits in terms of a reduction of cardiovascular risk can be expected.