[Hypertension: microvascular complications].

The arterioles, vessels situated before the capillary bed, are responsible for the increased systemic resistances characteristic of hypertension. In short, three abnormalities are observed in the arterioles of hypertensives: abnormally high vasoconstrictor tone, essentially due to sympathetic hyperactivity, hypertrophic remodelling or increased wall thickness/radius ratio of the arteriole promoting both the increase in vasoconstriction tone and reduction of the vascular lumen, rarefaction of the microvascular bed which contributes to the increase in the haemodynamic resistances. These three factors are observed to different degrees in all forms of hypertension; their influence varies with the organ involved and the stage of the disease. A change in therapeutic strategy has occurred over the last 20 years in the field of hypertension. Before the 1980's, anti-hypertensive therapy was essentially aimed at a vasomotor target: the drugs used had a vasodilatory effect on the resistive arterioles or decreased their response to vasoconstrictor agents. From the mid-1980's, a lot of research was made into the therapeutic possibilities of limiting or correcting the hypertrophic remodelling of the arteries and arterioles of hypertensive patients. In the last few years, the vascular rarefaction in hypertension has been considered to be a significant factor and the possibility of correcting the structural abnormality has become a new therapeutic option.