Effects of coumadin on the resolution of canine venous thrombi

Experimental thrombosis of the inferior vena cava was induced in 39 dogs to create a thrombus that could be embolized to a Greenfield filter for measurement of thrombolytic activity. In the series of 17 control animals, thrombus weight had decreased from 0.871 +/- 0.10 g to 0.477 +/- 0.08 g (P less than 0.05) at 2 weeks and from 0.884 +/- 0.097 g to 0.106 +/- 0.025 g (P less than 0.001) at 4 weeks representing 56 and 12%, respectively, of initial weight. In the series of 22 animals treated with coumadin, the resolution in thrombus weight was from 0.849 +/- 0.13 g to 0.171 +/- 0.14 g (P less than 0.02) at 2 weeks and from 1.031 +/- 0.34 g to 0.013 +/- 0.013 g (P less than 0.05) at 4 weeks representing 20 and 1%, respectively, of initial weight. These results show that in this model where venous flow is preserved around a trapped thrombus, lysis proceeds at a significant rate, yet can be accelerated by therapeutic levels of coumadin.