in a recent issue of critical care , we presented a series of 13 patients undergoing post - cardiotomy extracorporeal membrane oxygenation ( ecmo ) with bivalirudin - based anticoagulation . after this series , we satisfactorily continued this experience , reaching about 20 patients treated . however , we think that a word of caution should be added to our recently published experience . owing to its pharmacological profile , bivalirudin is rapidly cleaved by proteolytic enzymes , and its half - life is about 25 minutes when the renal function is normal . the use of bivalirudin for cardiopulmonary bypass ( cpb )   and ecmo   is a feasible option . however , it is recommended that , during cpb , blood stagnation in the circuit be avoided because the rapid cleavage of bivalirudin may result in thrombosis . the ecmo circuit is devoid of a reservoir , and therefore blood stagnation is usually not a circuit- related problem . conversely , under some circumstances , the cardiac chambers may act as a ' natural reservoir ' , which entails blood stagnation and the risk for spontaneous intracardiac thrombosis . this is particularly true in the case of a very large right or left atrium with insufficient venous drainage or the case of very poor ventricular systolic function with intraventricular blood stagnation . to avoid this condition , we think that maintaining a partial ecmo support , leaving a minimal degree of intracardiac blood flow , may be a reasonable choice . this may be checked by echocardiographic view of heart valve movement or simply by the observation of some degree of pulsatile arterial blood pressure . we think that , in the event of echocardiographic evidence of a ' smoke effect ' within one or more cardiac chambers , bivalirudin should be replaced by standard heparin anticoagulation . intracardiac thrombus formation during ecmo with heparin anticoagulation has been described as well , but the pharmacokinetic properties of heparin may limit the risk of thrombus formation due to blood stagnation .
bivalirudin has been proposed as the sole anticoagulant in patients under extracorporeal membrane oxygenation ( ecmo ) or cardiopulmonary bypass . 
 owing to the pharmacodynamic properties of bivalirudin , areas of blood stagnation should be carefully avoided in order to limit the risk of thrombosis . 
 the ecmo circuit has no reservoir and is usually devoid of blood stagnation areas . 
 conversely , under some circumstances , intracardiac blood stagnation areas may exist . in this case 
 , there is a potential risk for the spontaneous formation of an intracardiac thrombus . 
 we suggest that , under bivalirudin anticoagulation , a minimal degree of intracardiac blood flow with left heart valve movement is allowed .