Introduction: Microvascular free tissue transfer is a widespread method of reconstruction of complex surgical defects. However, there is still a small risk of flap compromise necessitating urgent re-exploration. The purpose of this study was to review a single institution incidence of microvascular complications in an effort to elucidate common causes as well as methods to avoid and manage these complications.

Methods and Materials: This was a retrospective review of 1193 free flaps performed between 1991-2002 for reconstruction of surgical defects of the head and neck (883), breast (155), trunk (38) and extremities (117) at a single cancer center. All patients who required emergent re-exploration were identified and their charts as well as a prospectively maintained flap database were reviewed. Vascular complications and methods used for their management were reviewed. Statistical analysis was performed using the Chi squared test with p < 0.05 considered significant. Results: A total of 82 (8.0%) patients required emergent re-exploration. The complete flap salvage rate in this group was 57%, partial salvage rate was 25%, and failure rate was 18%. Common causes for re-exploration were venous thrombosis (31%), hematoma or bleeding (33%), arterial thrombosis (10%), and complete flap loss (10%). The negative re-exploration rate was 7%. Arterial Thrombosis: Eight re-explorations were performed for suspected arterial thrombosis (mean 2.9 days). All re-explorations required arterial thrombectomy (Fogarty catheter), and anastomotic revision including vein grafts in 5 patients. Simultaneous venous thrombectomy and/or vein revisions were required in 5 cases. Intraoperative thrombolysis (strepto/urokinase) was utilized in 3 patients with established or extensive clot. The flap salvage rates were as follows: complete 38%, partial salvage 50%. There was 1 flap failure (12%). The single flap loss required delayed free flap reconstruction. Venous Thrombosis: There were 26 re-explorations for venous congestion or thrombosis (24 patients; mean 2.6 days). 23 re-explorations required thrombectomy and venous anastomotic revision including vein grafts (n=6). Intraoperative thrombolysis was used in 52% of patients all of whom had extensive clot. The flap salvage rates for venous thrombosis were as follows: complete 50% and partial 35%. Four flaps (15%) ultimately failed 2 of which required immediate second tissue transfer. The most common causes for venous thrombosis were extrinsic compression, pedicle kinking related to head position and tunneling, and intimal debris. There was no significant difference in salvage rate in flaps requiring secondary vein grafting as compared with those with anastomotic revision only. 45% of vascular thrombosis occurred more than 48 hours postoperatively; 10 thromboses (30%) occurred on postoperative day 4 or later. 93% of late thromboses occurred in the head and neck. There was no significant correlation between the time of re-exploration and salvage rate. Complete Flap Loss: Seven patients had necrotic non-salvageable flaps upon initial re-exploration (mean 8.6 days). Immediate secondary flap reconstruction was performed in 5 patients (local flap or second microvascular transfer). Delayed reconstruction was performed in 2 cases (second free flap, delayed bone graft).

Conclusions: Microvascular free tissue transfer is a reliable reconstructive technique with low failure rates. Head and neck free flaps should be monitored for at least 7 days due to the potential for pedicle kinking with neck movement. Salvage of free flaps is feasible even if they occur after post operative day 4 and should be attempted. Intraoperative thrombolytics should be used for patients with established or extensive clot. Vein grafts should be used for revision of anastomotic failure when indicated.