High and low molecular weight heparins do not modify red blood cell aggregability in vitro.

The usefulness of heparins as anticoagulants has been demonstrated, but their effects on hemorheological parameters, such as erythrocyte aggregability, are under discussion. If the heparins had adverse effect on erythrocyte aggregability, its use would be especially undesirable in patients with pathologies involving red blood cell hyperaggregability as is the case of cardiac disease. In the present study we examine the in vitro effect of unfractionated and fractionated heparins on red blood cell aggregability. The results show that heparins do not increase this rheological parameter but show a slight tendency to lower it.