vivo and post mortem dissolution rates of pulmonary emboli and venus thrombi in the dog

Post mortem and in vivo dissolution rates of freshly induced venous thromboemboli were de-termined in 87 dogs. In 63, fresh thrombi formed in the inferior vena cava (IVC) were embo-lized to the lungs. Dissolution rates were determined by comparing the embolic volume recovered at autopsy with the volume of a second (control) thrombus formed in the IVC. Embolic vol-ume recovered at 3 hr post mortem averaged 50.2 % of control. In dogs maintained alive, em-bolic volume fell to 48.4 % of control at 3 hr. With concomitant heparinization, only 34 % of con-trol embolic volume remained at 3 hr. In 24 dogs, thrombi were formed in the jugular veins. No dissolution of these thrombi occurred up to 6 hr post mortem. When they were exposed to circulating blood in vivo, only 67.2 % of control volume was recovered at 3 hr. The rapid re-duction of thromboembolic volume observed appears to be due to thrombolysis via the fibrino-lytic system. The prompt and substantial post mortem and in vivo reduction of embolic volume should be considered in studies dealing with the cardiopulmonary responses following em-bolism in experimental animals, and perhaps, in man. Additional Indexing Words: Pulmonary emboli Post mortem lysis of pulmonary embol