INTRAARTERIAL THROMBOLYSIS USING RT-PA FO R THE TREATMENT OF OCCLUDEDINFRAINGUINAL BYPASSES

From July 1990 to July 1993, we performed 41 percutaneous intra-arteri al thrombolysis procedures for the treatment of obstructed infra-ingui nal bypass grafts in 32 patients. There were 27 men and rive women wit h a mean age of 63 +/- 17 years (range 21 to 83 years). The symptoms o f occlusion were intermittent claudication in three cases, rest pain i n 12 cases, severe ischemia without sensitivo-motory loss in 26 cases. Bypasses were achieved using a prosthesis in 18 cases (43.9 %), a sap henous vein in 10 cases (24.4 %), an arterial allograft in nine cases (21.9 %), and a composite prosthesis-vein graft in four cases (9.8 %) (table I). The distal anastomosis of the bypass graft was located on t he popliteal artery in 26 cases (63.4 %) and a crural artery in 15 cas es (36.6 %). The mean duration of the occlusion was 4.9 +/- 3.4 days ( range 1 to 15 days). The percutaneous approach was through the contral ateral common femoral artery in 26 cases (63.4 %), through the ipsilat eral common femoral artery in seven cases (17,1 %), through the left h umeral artery in eight cases (19,5 %). In all cases the thrombolytic a gent was the recombinant tissue-type plasminogen activator (rt-PA). Ea ch procedure began with the injection of a five milligram bolus of rt- PA into or onto the thrombus followed by infusion of rt-PA into the th rombus at a dose of 0.05 mg/kg/h. Intravenous heparin was simultaneous ly administered. Serum fibrinogen, prothrombin time, and partial throm boplastin time (PTT) were measured every three hours. Arteriography wa s performed firstly after injection of the rt-PA bolus and then every three hours during the first nine hours to assess the progress of thro mbolysis and to adjust the position of the thrombolysis catheter. Ther eafter arteriography was performed as mandated by clinical or laborato ry findings. Lytic therapy was discontinued either when flow in the by pass had been completely restored, when no further progress could be a scertained by arteriography, or when complications occurred. If the pr ocedure was sucessful, the dose of heparin was increased in order to m aintain PTT at twice the baseline value. The intra-arterial introducer valve was left in place until normalization of fibrin levels. Thrombo lysis was considered as successful when angiograms demonstrated that t he bypass graft was patent and when no residual thrombus could be dete cted in the bypass graft or distal arteries (fig. 1). The procedure wa s considered as unsuccessful when catheterization of the occluded bypa ss graft failed, when flow was not restored, when lysis was incomplete , and/or when residual thrombus was detected in the bypass graft or di stal arteries. The mean duration of infusion was 10.8 +/- 10.3 hours ( range 1 to 58 hours). In four cases the procedure lasted more than 24 hours. The mean total dose of rt-PA was 30.6 +/- 13.5 mg (range 8 to 7 0 mg). The mean minimum serum fibrogen level during the procedure was 1.9 +/- 1.1 g/l (range 0.2 to 4.5 g/l). In nine cases fibrogen level f ell below one g/l. The outcome of thrombolysis was considered as succe ssful in 30 cases (73.2 %) (table II). In 20 of these cases, the cause of occlusion was identified and treated. In the remaining 10 cases th e cause of bypass graft occlusion could not be determined. The outcome of thrombolysis was considered as unsuccessful in 11 cases (26.8 %)(t able III). In six of these cases, the cause of occlusion was identifie d. Success rate in function of graft material is shown in table IV. Ei ght patients (19.5 %) presented procedure-related complications. In on e case, acute ischemia with sensitivomotory loss occured. Severe hemor rhage due to a decline in fibrogen levels below 0.5 g/l was successful ly controlled by intravenous administration of fresh plasma in three c ases but led to death by intracranial hemorrhage in one case. Hematoma s at the puncture site required blood transfusion in three cases. In o ur series thrombolysis achieved a success rate in about 75 % of cases of occluded bypasses (table V). In more than 50 % of cases, even if th e procedure was unsuccessfull, the cause of occlusion could be determi ned (fig. 2, 3 and 4) and additional procedure simplified. Intra-arter ial thrombolysis should not be considered as a risk-free, minimally in vasive alternative to conventional surgery. Prevention of complication s requires careful patient selection and close surveillance of clinica l signs and laboratory findings during the procedure