Pathophysiology of Blood Rheology in Ischemic Diseases

Abstract

Some decades ago various authors described increased values of blood and plasma viscosity in ischemic diseases. In 1975 Reid et al. as well as Ehrly and Köhler found an impaired red cell filterability in patients with chronic occlusive peripheral diseases [8, 4]. Reviewing the literature to date, there are a lot of papers describing impaired flow properties of blood in various ischemic diseases [7]. So it is not surprising that the term hyperviscosity is often used in connection with vascular diseases. However, if we analyze these papers, it must be stressed that the finding of impaired flow properties of blood obtained from the antecubital vein is only valid from the statistical point of view. In the individual patient there may be normal values for hemorheological parameters in spite of the presence of ischemic disease. On the other hand, increased blood and plasma viscosity values can be found without any signs of ischemia or hypoxia. The questions which arise from this are: whether impaired hemorheological values are of pathophysiological relevance or whether these in vitro findings are only epiphenomenal, and, what are the pathophysiological mechanisms leading to impaired tissue perfusion and tissue supply.