Effect of heparin, tissue plasminogen activator, and increased intracaval pressure on the acute morbidity of Greenfield filter insertion.
The effects of anticoagulation, thrombolytic therapy, and augmented intracaval pressure on the risks of acute caval hemorrhage from Greenfield filter insertion have not been rigorously investigated. To examine these risk factors, the device was placed in three groups of five dogs. Group 1 served as controls, with filter placement only. Groups 2 and 3 received anticoagulants before surgery. Group 3 was additionally given a continuous infusion of tissue plasminogen activator begun immediately after filter insertion. Animals were killed after a 6-hour period of observation and measurement. A second phase was carried out at autopsy in group 3: intracaval pressure was augmented and its effects on caval integrity noted. During the period of observation there were no significant decrements in central venous pressure or hematocrit. At autopsy, no evidence of caval hemorrhage and no caval perforations were found. Increased intracaval pressure did not alter these findings. These results support the clinical experience with the device, and suggest that the risk of acute hemorrhage from a properly seated filter is minimal, even with concurrent use of heparin and thrombolytic agents or high caval pressures.