Anticoagulation during use of a left ventricular assist device

Thirty-six mongrel dogs underwent 24hr left ventricular assist. The VAD was placed between the left atrium and the descending aorta, and the dogs were divided into four groups according to type of anticoagulation: no anticoagulation, argatroban, nafamostat mesylate, and nafamostat mesylate + prostacyclin analog. Results of this animal experiment revealed that a newly developed synthetic thrombin inhibitor argatroban can prevent activation of the intrinsic coagulation pathway. Argatroban is efficient under any blood coagulative condition, even lack of anti-thrombin III, because of its direct inhibitory effect on thrombin, making argatroban more useful than heparin as an anticoagulant for LVAD. Argatroban, as well as heparin, provides marked and significant prolongation of the prothrombin time from early assisted circulation, but produces a bleeding tendency. Nafamostat mesylate can maintain blood coagulation parameters within the acceptable range. Combined administration of nafamostat mesylate and a prostacyclin analog cause the least decrease in fibrinogen and alpha2-plasmin inhibitor among the four groups and causes no significant prolongation of prothrombin time.