Rheological study on vascular occlusion and cellular hyperviscosity syndrome in polycythemia vera

Whole blood viscosity was determined in 10 patients with polycythemia vera and 129 normal controls using a cone-plate type rotational viscometer at 37 degrees C. Three of the patients with polycythemia vera exhibited vascular occlusions including cerebral and myocardial infarction. The remaining patients had transient complications such as headache, short of breath and hot flush probably due to the circulatory disturbance. All patients had a blood viscosity higher than normal determined at a shear rate between 37.5 and 375 sec-1. This indicated that the patient might be in the imminent danger of occlusion when the viscosity is above twice the normal mean value. Clinical symptoms appeared in all patients at least over the value of the mean plus 3 standard deviations of the normal controls in the viscosity at a shear rate between 37.5 and 375 sec-1. The present study represented a close relationship between the occurrence of occlusive and/or reversible lesions and the elevated values of whole blood viscosity in polycythemia vera. The phlebotomy and fluid infusion therapy was valuable in most cases because the viscosity was decreased at once to the normal level. In addition an extended classification of hyperviscosity syndrome consisting of cell, plasma and combined hyperviscosity is proposed.