Studies on blood rheology in patients with primary pulmonary hypertension.

The rheologic properties of blood were studied in 6 patients with primary pulmonary hypertension (PPH) and compared with those of a control group of 10 healthy subjects. Blood viscosity was studied with a rotational viscometer and blood cell deformability with a filtrometer giving values for clogging particles (CP) and red cell transit time (RCTT). Blood viscosity at varying shear rates was found to be increased both at natural (p less than 0.025-0.005) and standardized hematocrit, 45% (p less than 0.05 at 40 s-1) in patients with PPH. Red cell deformability was reduced as indicated by a significant increase of RCTT (p less than 0.01). Increased values for hematocrit (p less than 0.001), hemoglobin concentration (p less than 0.001), and erythrocyte count (p less than 0.005) were found and decreased values for mean corpuscular hemoglobin concentration (MCHC) (p less than 0.025) and HDL cholesterol (p less than 0.005). Plasma viscosity, white cell deformability, white cell count, mean corpuscular volume (MCV), and plasma fibrinogen concentration did not significantly differ from the values found in the control group. It is concluded that patients with PPH have impaired blood rheology. The hemorheologic abnormalities in these patients may be of hemodynamic significance.