Effects of anticoagulants on patency of venous graft were studied on dogs.
The following results were obtained.
1. A portion of superior vena cava was replaced with synthetic graft in 32 dogs, of which 20 were given Heparin and/or Warfarin postoperatively. The patency rate of graft was 77% in anticoagulant group compared to 50% in control group. However, there were 7 early deaths (35%) due to bleeding in the former group.
2. A portion of femoral vein was replaced with tetron graft (6mm in diameter) in 14 dogs and anticoagulants were given post-operatively. All grafts except one, were thrombosed within one week. Effects of anticoagulant on graft patency were not observed.
3. Patancy rate of patch graft with synthetic material for reconstruction of femoral and external carotid vein was ranging in from 50 to 60%. No effects of anticoagulants were observed.
4. Synthetic graft is not applicable to reconstruction of small vein and auto-vein graft or patch graft are suitable. Anticoagulants are not helpful in that case.
5. Anticoagulants should be given during operation in venous reconstraction, continued at least two weeks post-operatiovely and then gradually discarded.
Anticoagulant therapy was performed on 37 patients with thromboembolism and cases who underwent vascular surgery between Oct. 1962 and Dec. 1964.
The following conclusion was obtained.
1. Generally, results of anticoagulant therapy were satisfactory.
2. Heparin 1 mg per kilogram of body weight was given as an initial dosis and proper dosis was followed intermittently at 4 hours interval to keep coagulation time 2 or 3 times as normal.
Warfarin, 15.5mg on an average, was given as an initial dosis, then half as the second, and then 3.6mg (0.06 mg/kg in male adult, 0.09 mg/kg in the aged) as an maintanance. Prothrombin time was kept in 10 to 25%, and thrombotest in 5 to 15% during treatment.
3. Anticoagulant therapy should be continued as long as possible in patients with chronic arterial occlusive disease as Buerger's disease and arteriosclerosis obliterans.
It should be used until symptoms subside in patients with venous thrombosis and thrombophleditis.
It is preferable to continue anticoagulant therapy through life in patients with valvular heart disease who developed embolism unless radical operation is applicable.
It is not recommended for possible bleepings after aortic surgery, though it is preferable to use anticoagulants as long as possible after grafing for peripheral artery or vein.
4. Serious side effects are not acompanied to anticoagulant therapy provided it is used with meticulous care.