Myocardial Blood Flow and Oxygen Uptake During Acute Red Cell Volume Increments

Abstract

The role of red cell mass in the regulation of coronary blood flow and myocardial oxygen consumption has been examined after acute transfusion of sedimented red cells. Patients with substantial blood-loss anemia had a lower than normal left ventricular oxygen uptake, despite a high myocardial blood flow at rest. A 50% rise of hematocrit reduced coronary flow markedly. Although systemic arterial pressure, cardiac output, and left heart work rose, myocardial oxygen consumption was unchanged. Red cell transfusion of normovolemic dogs resulted in a decrease of both myocardial flow and oxygen uptake associated with an elevation of time-tension index and left ventricular work, accelerated isometric contraction and prolonged systole. There was no evidence of ischemia or change of left ventricular hemodynamic parameters that would account for the reduced myocardial blood flow and oxygen uptake. These findings, in the presence of an increased oxygen carrying capacity and extraction, would appear to be related principally to enhanced blood viscosity.

Blood Replacement

“…On the other hand they have shown that polycythemia in normovolemia does not cause improvement but rather deterioration of the oxygen supply, since the peripheral resistance increases due to a rise in viscosity; and coronary flow decreases [1169, 1702].…”

Circulatory haemodynamics after blood transfusion in chronic severe anaemia.

“…In their patients, however, labour was imminent, and failure occurred during or within a few hours of labour, and it is not unlikely that the stress of labour itself was responsible for untoward reaction and not the transfusion. Regan et al (1963), however, noted no cardiac handicap after rapid transfusion of 800 ml. packed red cells at a rate of 18 ml./min.…”

“…Sharpey-Schafer (1945), Frye andBraunwald (1960), andDuke et al (1964) observed no consistent haemodynamic changes, but Regan et al (1963) found a consistent increase in cardiac output, mean arterial pressure, and left ventricular work after transfusion. The present study also showed no consistent pattern of haemodynamic alterations immediately after transfusion, except that the total blood volume increased in every case.…”

“…Reports of effects of blood transfusion on circulatory haemodynamics in patients with chronic severe anaemia are few, and the number of patients studied in these reports is small (Sharpey-Schafer, 1945;Regan et al, 1963;Duke, Herbert, and Abelmann, 1964). The present investigation was, therefore, undertaken to determine the haemodynamic alterations and possible dangers of circulatory overloading after moderately rapid transfusion of whole citrated blood in patients with chronic severe anaemia, including patients with clinical heart failure, cardiac enlargement, or electrocardiographic abnormalities, and to determine the duration of haemodynamic alterations.…”

Heart

“…Regan et al (109) showed that increasing the red cell mass, by red cell transfusions in both human subjects and in normocytic dogs, produced a linear decrease in coronary blood flow and myocardial oxygen uptake. This decrease was associated with a prolonged systole and with elevation in left ventricular work, cardiac output, and arterial pressure.…”