Pharmacological thrombolysis: the last choice for salvaging free flaps

Microvascular free flap transfer has become a prevailing surgery with a failure rate of <5%. However, pedicle thrombosis occurs more frequently than indicated by the failure rate. This difference is due to the successful salvage of failing flaps. During exploration, thrombi are often encountered at anastomotic sites, whereas these causes could not explain vascular compromise in other patients. Thus, we hypothesized that thrombogenic processes might occur at remote sites, specifically within microvessels of the transferred flap. This study retrospectively evaluated 323 patients who underwent microvascular free flap transfer between March 2012 and October 2016 at Korea University Guro Hospital. All patients requiring emergency exploration within 7 days after surgery were retrospectively reviewed. Of patients, 15 required explorative surgery for suspected circulatory compromise. Eight were diagnosed with thrombosis at the perianastomotic site and salvaged in accordance with our protocol. There was no detectable thrombosis at the anastomotic site in seven patients, including one patient in whom thrombosis resolved with topical papaverine application and heparinization. The remaining six patients were diagnosed with intra-flap microthrombosis without discernable thrombosis at the anastomotic site. All patients were treated following our urokinase administration protocol and salvaged without complications. Possible external causes should first be evaluated when salvaging free flaps; in the absence of such evidence, urokinase administration may be utilized as a last resort. This study is the first report describing the effectiveness of pharmacological thrombolysis in resolving intra-flap microthrombosis. Furthermore, a safe and efficient urokinase administration protocol is suggested for perianastomotic thrombosis and intra-flap microthrombosis.