A comparison was made between several characteristics of tissue-type plasminogen activator (t-PA) and urokinase (UK), potentially useful in microsurgery to restore perfusion to ischemic free-tissue transfers. An intraarterial infusion of one of the drugs (or normal saline [NS] as a control) was performed in conjunction with a rat femoral vein clot model. Both t-PA and urokinase were effective in lysing 100 percent of the venous clots on the side of infusion. This occured in only 25 percent of controls (p = .0035). Thrombolysis on the contralateral side, a measure of systemic effect, occurred in 38 percent, 50 percent, and 13 percent of veins using t-PA, UK, and NS, respectively (t-PA vs. UK p = 1.0, t-PA vs. NS p = .28, UK vs. NS p = .14). Rethrombosis occurred in 13 percent and 25 percent of ipsilateral veins treated with t-PA and urokinase, respectively, and in one of the two veins that had resumed flow during saline infusion (t-PA vs. UK p = .30) Scanning electron microscopy was performed 4 hr and 48 hr after thrombolysis. No differences between thrombolytic agents was noted in terms of residual thrombus and vessel characteristics. The data suggest that t-PA and urokinase are effective, with no clear advantage of one agent over the other.
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