Outcome of popliteal artery aneurysms after exclusion and bypass: significance of residual patent branches mimicking type II endoleaks.

Purpose: Popliteal aneurysms (PAs) often are treated with exclusion and bypass. However, excluded aneurysms can transmit systemic pressure from persistent flow through collateral arteries (endoleak), resulting in aneurysm growth and rupture. We used duplex ultrasound scanning for postoperative surveillance more than 2 years after PA repair with exclusion and bypass, to determine the presence of flow and aneurysm growth.

Methods: From 1995 to 2001, 23 patients with 26 PAs (mean diameter, 3.2 cm; range, 1.6-5.6 cm) underwent surgical repair and were available for more than 2 years of follow-up. The popliteal artery was ligated proximal and distal to the aneurysm, and autogenous revascularization was performed. All patients who underwent PA endoaneurysmorrhaphy through a posterior approach were excluded from the study. During long-term follow-up, aneurysm sac flow and size were evaluated with duplex ultrasound scanning, computed tomography, or magnetic resonance angiography, and standard angiography. Patients with increased PA size and persistent flow were offered repair through a posterior approach.

Results: Over 7 years, 26 PAs (symptomatic, 11; asymptomatic, 15) treated with aneurysm exclusion and bypass were available for more than 2 years of follow-up (mean, 38 months; range, 24-78 months). In the postoperative period 16 PAs (62%) became thrombosed, 10 (38%) had persistent collateral flow through geniculate vessels, 6 (23%) increased in size, and 3 (12%) ruptured; 1 (4%) resulted in limb loss. Operative findings for all ruptured PAs and 3 of 6 PAs with increased sac size that underwent aneurysm sac exploration and endoaneurysmorrhaphy revealed retrograde flow through geniculate vessels, mimicking type II endoleak.

Conclusions: These findings question the effectiveness of PA exclusion through proximal or distal ligation and bypass. In addition, retrograde flow into the aneurysm sac (ie, type II endoleak after endovascular abdominal aortic aneurysm repair) may transmit systemic pressure that can result in aneurysm rupture. We recommend PA treatment with aneurysm sac decompression and ligation of geniculate vessels whenever possible and routine postoperative surveillance of the excluded aneurysm sac.