Left ventricular function in chronic anemia: evidence of noncatecholamine positive inotropic factor in the serum.

The enhanced left ventricular (LV) performance observed in anemia has been attributed to changes in preload and afterload. Whether there is a concomitant increase in contractility is controversial. Seventeen patients with chronic anemia (hematocrit range 17 to 30%) and 17 control subjects, matched by age and sex, were studied. In 10 patients and 10 control subjects (group I), a noninvasive evaluation of LV function through M-mode echocardiography and cuff blood pressure recording was performed. In patients with anemia, stroke volume increased 43% (p less than 0.01), fractional shortening 21% (p less than 0.001), and mean rate of circumferential shortening 32% (p less than 0.001). In patients with anemia, end-systolic stress decrease 27% (p less than 0.05) and diastolic blood pressure 21% (p less than 0.001). The effect of serum from these patients and control subjects on the development of isometric tension by isolated cat papillary muscles was assessed compared with the basal (Ringer-Locke bath) values. Anemia serum increased maximal developed tension 21% and maximal rate of tension development 20% relative to basal levels. These changes were significantly higher (p less than 0.001) than the increases produced by control serum (8% and 7%, respectively). In the 7 patients with anemia in group II and their matched controls, the in vitro isometric tension characteristics were assessed before and after blocking beta adrenoreceptors with propranolol, 10(-6) M. The observed increase in the developed tension persisted after beta blockade, as well as the enhancement of the maximal rate of tension development. Plasma catecholamine levels in this group II were within the normal range.(ABSTRACT TRUNCATED AT 250 WORDS)