Heparin therapy for thromboembolic disorders. A prospective evaluation of 134 cases monitored by the activated coagulation time.

One hundred thirty-four patients with venous thrombosis or pulmonary embolism, confirmed by radiological techniques, received continuous-pump heparin therapy while their responses were monitored by the activated coagulation time (ACT). The suggested protocol was as follows: (1) give an intravenous bolus of about 50 units/kg; (2) follow with 15 to 25 units/kg/hr; (3) modify infusion rate to maintain ACT of 150 to 190 s; (4) after two or three days with ACT in target range, start oral warfarin sodium therapy; (5) after three to five days of warfarin therapy, if prothrombin time is two to 2 1/2 times the control value, discontinue heparin administration. One hundred thirty-two patients responded, with no heparin failures. Dangerous bleeding occurred in two who received excessive amounts of heparin. Some patients, mostly with short ACTs, responded slowly; some, many with long ACTs, had minor bleeding. The protocol proved successful and safe when followed closely.