Irreversible Limb Ischemia Due to Embolizing Aneurysm of the Superficial Femoral Artery

Introduction

True aneurysms of the superficial femoral artery (SFA) are considered a rare entity, often presenting in concurrence with other peripheral or abdominal aortic aneurysms. ¹ SFA aneurysms may remain undetected due to their deep location; once symptomatic, disastrous complications may occur, with rupture being the most common manifestation. In this report, we describe a case of a 75-year-old male patient presenting with irreversible limb ischemia due to massive distal embolization from a large proximal SFA aneurysm, resulting in limb loss. Informed consent has been obtained from the patient and patient’s family for publication of the case report and accompanying images.

Case Presentation

A 75-year old male presented to the Emergency Department due to painful left lower limb and multiple sites of bluish discoloration in the foot, calf and knee (Figure 1A-C). His previous medical history included coronary disease but no previous history of intermittent claudication.

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Figure 1.

Irreversible foot ischemia with skin lesions at the foot (A), posterior tibial surface, (B) and at the knee (C), due to thromboembolization from the large aneurysm of the superficial femoral artery (D).

Upon clinical examination, paralysis (drop foot), profound sensory loss and inaudible arterial and venous Doppler signals in the foot were revealed, consistent with irreversible ischemia (Grade III in the Rutherford scale). ² A large mass in the upper thigh was detected upon palpation (Figure 1D). Computed tomography angiography (CTA) revealed a 5-cm aneurysm of the proximal SFA with abundant intraluminal thrombus (Figure 2A). A small abdominal aortic aneurysm (AAA) of 5 cm with intraluminal thrombus was also discovered in the CTA. The SFA lumen was patent along its entire length (Figure 2B-D). On the contrary, the popliteal artery was thrombosed. Since the patient had no previous history of intermittent claudication or other embolizing source, the embolizing origin was attributed to the SFA aneurysm.

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Figure 2.

A. The computed tomography angiography showed a 5 cm aneurysm at the proximal segment of the ipsilateral superficial artery with abundant intraluminal thrombus. The vessel lumen was patent along the entire length of the thigh, from the end of the aneurysm (B) to the mid-(C) and distal thigh (D).

Laboratory examination revealed high levels of creatine phosphokinase (CPK: 18.000 IU/L) along with elevated values of glutamic-oxaloacetic transaminase (SGOT) and glutamic pyruvic transaminase (SGPT), 427 and 333 IU/L, respectively. Accordingly, the patient was subjected urgently to limb amputation above the knee and excision of the femoral aneurysm (Figure 3). Unfortunately, despite the uneventful operation, the patient suffered from cardiac arrest and died on the second postoperative day.

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Figure 3.

Intraoperative image of the excised aneurysm with the intraluminal thrombus.

Discussion

Aneurysms of the SFA comprise a rare entity accounting for 1-2.6% of peripheral arterial aneurysms and occurring more often in elderly. They comprise 15% of all femoral aneurysms, with common femoral artery (CFA) and profunda femoral artery (PFA) affected in 80% an 5%, respectively.^1,3 The deep location of the SFA and PFA in the thigh and coverage by muscle layers may contribute to the low recorded incidence of these aneurysms. Synchronous presence of AAA and SFA aneurysms has been reported to be as high as 40%. ⁴

Cutler and Darling in 1973 and Amer et al., more recently, classified the aneurysms of the upper thigh based on their location in the femoral bifurcation. Type-I consists of CFA aneurysms, type-II includes aneurysms of the femoral bifurcation, type-III refers to sole SFA aneurysms and type-IV involves aneurysms of the PFA.^5,6 Comparing to CFA and PFA, SFA aneurysms can be located in various locations in the thigh. Perini et al. identified the middle and distal third of SFA as the commonest location of aneurysm presentation, with 15% of the aneurysms detected in the proximal SFA, 22% and 59% in the mid and distal third, respectively, while only 4% involved the entire SFA length. ⁷ Acute limb ischemia was reported in 22% of patients with an amputation rate of 7% and limb salvage rate of 88% at 5 years. ⁷

Despite the available diagnostic modalities, the deep location of SFA aneurysms renders them undetected to physical examination, unless significantly enlarged at presentation. ¹ They can present as pulsating mass accompanied with local discomfort and pain or claudication and compression effects such as deep venous thrombosis; yet, devastating outcomes of rupture and acute limb ischemia may also occur. ¹ Interestingly, thrombosed SFA aneurysms may be underappreciated, since such patients may present with symptoms of an atherosclerotic SFA thrombosis. Comparing to SFA, popliteal aneurysms can be often diagnosed while asymptomatic.^3,4 Leon et al. reported that more cases of SFA aneurysms presented with rupture than distal ischemia. ³

Our case involved the proximal SFA without involvement of the femoral bifurcation. As reported, an AAA with intraluminal thrombus was also discovered in the CTA. Even though distal embolization has been rarely described as first manifestation of AAA, the presence of aberrant thrombus -as seen intraoperatively- in the SFA aneurysm of our patient was considered the cause of the massive distal embolization. In contrast with the high incidence of rupture accompanying SFA aneurysms, limb loss is uncommon with prompt surgical intervention, even after ligation of the artery; yet, there are no pooled long-term data in the literature to date. ² In our case, the clinical and laboratory findings, as well as the absence of revascularization target rendered amputation as the procedure of choice. Unfortunately, the severity of the ischemia in association with the patient’s medical history of coronary disease led to cardiac arrest on the 2nd postoperative day.

The rationale of treating SFA aneurysms follows the same pattern as with any aneurysm: prevent or treat rupture and distal embolization and restore lower extremity perfusion. SFA aneurysm should be always treated when symptomatic, but, there is no consensus for asymptomatic ones. Generally, treatment is indicated for SFA aneurysms larger than 35 mm.^3,8-10 According to Cutler and Darling, 3 factors should be taken into consideration to treat SFA aneurysms: the location of the PFA origin, the patency of the femoropopliteal segment and the patency of the aneurysm. ⁵ Open and endovascular options are available based on the location of the aneurysm. Femoropopliteal synthetic or saphenous vein bypass is implemented in case of mid-distal aneurysms; if anastomosis below-the-knee is required, it would be advisable to use an autologous saphenous vein graft.^8-11 When presenting with massive life-threatening bleeding, sole aneurysm ligation is advisable. Furthermore, hematoma drainage is described to avoid tissue compression. Endovascular repair with stent-grafts is a considerable option given the fact that the localization of the SFA prevents kinking of the stent-graft. ¹²

Conclusion

Degenerative SFA aneurysms are usually large and symptomatic at presentation, occurring in elderly. Although their commonest manifestations are rupture and thrombosis, they can attribute to massive peripheral thrombosis, leading to irreversible limb ischemia and representing rarely life-threatening situations.