Prophylaxis for postoperative deep-vein thrombosis. Synergistic effect of heparin and dihydroergotamine.

Randomized clinical trials in 300 patients undergoing major abdominal surgery or hip replacement arthroplasty were performed to investigate the efficacy of dihydroergotamine mesylate, heparin calcium, or a combination of dihydroergotamine with heparin in preventing postoperative deep-vein thrombosis (DVT). The diagnosis of DVT was established by an uptake test using fibrinogen labeled with iodine 125; in patients undergoing hip replacement, phlebography was also employed to confirm or refute the presence of isotopic thrombi. The data indicate that the combination of dihydroergotamine and heparin is more effective than heparin or dihydroergotamine alone in preventing DVT.