Selective Hemapheresis, an Effective New Approach in the Therapeutic Management of Disorders Associated with Rheological Impairment: Mode of Action and Possible Clinical Indications

Abstract

The in vitro measurement of whole-blood viscosity, plasma viscosity, and erythrocyte aggregability is easy to perform, but they only allow a partial insight into the complexity of blood flow characteristics; however, they permit definition of the rheological properties of new hemorheological therapeutic modalities such as extracorporeal plasma therapy as described in this paper. Under more theoretical aspects, it becomes obvious that such hemorheological approaches should either improve the vasomotoric properties of blood vessels, reduce the circulating red blood cell concentration, or improve the viscosity by reducing the concentration of hemorheologically relevant plasma proteins. In this review, the rheological effect of a single apheresis treatment with different devices was compared. Due to their differences in selectivity, the extracorporeal methods have different effects on the rheologically relevant plasma proteins, and, therefore, their rheological effectiveness differs remarkably. Today, the classical blood letting and plasma exchange treatment have been replaced by erythrapheresis and selective devices for extracorporeal plasma treatment, respectively. For more than 10 years, the following 5 more-or-less selective apheresis procedures are commercially available: immunoadsorption, differential filtration, polyanion adsorption by dextrane sulfate as well as by polyacrylate, and polyanion precipitation by heparin as polyanion. The last three procedures are semiselective and, therefore, relatively unspecific whereas immunoadsorption only affects the plasma lipoprotein concentration. Several studies have shown the effective use of extracorporeal hemorheotherapy for the treatment of various diseases including macro- and cryoglobulinemia, Raynaud's disease, hyperlipoproteinemia (often characterized by premature atherosclerosis and coronary heart disease and peripheral arterial occlusive disease), cerebral multi-infarct demention and acute ischemic stroke, sudden hearing loss, and acute occlusion of the central retinal artery.