[Significance of the rheological properties of blood in peripheral vascular pathology]

The rationale of the hemorheologic approach to the pathophysiological knowledge and to the treatment of obstructive arterial diseases of the limbs is discussed in this paper. Indeed, the hemodynamic concepts are the natural frame in which the hemorheologic phenomena have to be considered. Proceeding from this background, it seems evident that the viscosity of blood and its major determinants have a limited role in the regulation of blood flow and pressure gradient through a stenotic artery. On the contrary, viscosity factors are of outstanding significance in the regulation of blood flow in the microcirculation, especially in presence of a reduced perfusion pressure and of exhausted arteriolar vasodilation capacity. Consequently, therapeutic measures capable of modifying one or more viscosity determinants may improve blood flow in the microcirculation of territories related to a stenotic artery. Baseline alterations of viscosity or viscosity determinants may be found in patients with obstructive arterial disease, being classified as primary, associated or secondary to arterial obstruction and ischemic damage. However, the presence of such baseline changes is not relevant to the indication of hemorheologic treatments.