The role of hemorheologic factors in the coronary circulation

Abstract

Coronary resistances of dogs with normal coronaries were measured before and after the hematocrit values were increased by exchange transfusion of packed red blood cell suspensions. Coronary resistances increased about 9% in this group. In a second group of dogs, experiments were performed after the coronary arteries were critically stenosed. The changes in coronary resistances were more prominent in the critical stenosis group. Blood viscosity measured at a hematocrit of 45% and erythrocyte deformability indexes were also increased in the coronary sinus blood after the exchange transfusion of packed cells. These findings imply that there is a close relationship between the rheologic properties of blood and coronary circulation. This relationship may include a positive feed-back, which will result in detrimental etTects on blood rheologic parameters.