Changes in Blood Viscosity , Hematocrit Value , and Fibrinogen Concentration in Subjects with Congestive Heart Failure

THE increased incidence of thrombo-occlusive complications in subjects with congestive heart failure is clearly recognized. Thus, pulmonary, cerebral, and myocardial infarction, thrombophlebitis, and mesenteric thrombosis are sufficiently frequent complications to compel some to include anticoagulant therapy in the routine management of cardiac decompensation. The fundamental cause of this tendency toward thrombosis has not been elucidated; hypercoagulability has been suggested but never clearly demonstrated. It has been observed that the critical period for thrombotic complications is during diuresis and restoration of compensation.' The present study was therefore undertaken to examine day-to-day changes in blood viscosity during this treatment interval, to assess the role, if any, of these changes in the tendency toward thrombosis. Measurements were made at the height of the congestive syndrome and were repeated at frequent intervals as compensation was restored. Attempts were made to correlate the changes encountered with alterations in hematocrit level, plasma volume, and fibrinogen concentration. Problems inherent in the measurement of blood viscosity have been amply reviewed by others.2 4 Inasmuch as blood is a "non-Newtonian" suspension of erythrocytes in a 7per cent protein solution, the viscosity of this fluid, by definition, is dependent upon the rate