Predictors of Limb Outcome Following Arterial Ligation of Infected Femoral Pseudoaneurysms in Drug Addicts

Introduction - Infected femoral pseudoaneurysms in intravenous drug abusers present a challenging situation to the vascular surgeon. Infection renders the arterial wall unreconstructable and arterial ligation usually remains the only viable option. Following ligation however, the decision whether immediate revascularization is deemed necessary or not remains controversial. Primary revascularization carries a high risk of infection and secondary haemorrhage, while delaying revascularization can jeopardize limb viability with subsequent risk of limb loss. In the absence of objective predictors that can guide decision making, there is no worldwide consensus regarding the optimum management. Method - We prospectively studied the outcomes of 20 intravenous drug abusers presenting with infected femoral pseudoaneurysms who underwent arterial ligation, evacuation of haematoma, and local wound debridement. We aimed mainly to identify certain potential predictors affecting overall limb outcome namely: 1)Mode of presentation (impending vs. ruptured); 2)Anatomical site of arterial ligation (above vs. below inguinal ligament); 3)Pedal doppler flow post-ligation; 4)Ankle brachial pressure index (ABI) pre and post ligation Results - Following ligation the overall outcome was as follows: 14/20 patients (70%) were compensated; 6/20 patients (30%) were critically ischemic following ligation where four patients required revascularization by extra-anatomical bypass, while two patients were deemed unreconstructable (due to extensive skin and soft tissue necrosis) requiring hip disarticulation. While eight patients presented with impending rupture (7/8 were compensated), twelve patients presented with frank ruptured pseudoaneurysms (7/12 were compensated) which was statistically insignificant. All four patients who had arterial ligation performed proximal to the inguinal ligament were critically ischemic after ligation while when the level of ligation was below the inguinal ligament 14 out of 16 patients were compensated (significant). Pedal doppler flow signal was detected in ten patients only intraoperatively. However, four more patients regained Doppler signal in the ward few hours after the operation. All 14 patients with Doppler signal were compensated and required no further revascularization for limb salvage till discharge from hospital. In compensated patients the mean pre-operative ABI was 0.88 and the mean post-operative ABI was 0.49 with an average ABI drop of 0.39. However, in patients who required revascularization or amputation, the mean pre-operative ABI was 0.83 and the mean post-operative ABI was 0.00 with an average ABI drop of 0.83 Conclusion - In drug addicts with infected femoral pseudoaneurysms, arterial ligation with local debridement without revascularization salvaged 70% of limbs in our study. The detection of pedal Doppler flow after ligation can stratify patients in whom revascularization might not be required for limb salvage. Additionally all efforts should be made to ligate the femoral artery below the inguinal ligament to preserve important juxta-inguinal collateral branches that can have great impact on limb outcome after ligation.