Pseudoaneurysm of the sural artery: a rare complication of lower limb angioplasty

Introduction

Percutaneous transluminal angioplasty (PTA) is a common therapeutic option for many patients with peripheral vascular disease. It is estimated that approximately 8800 femoral angioplasties were performed in England and Wales between 2010 and 2011. ¹

Previous studies have shown that the overall rate of all complications following lower limb PTA is between 2.3% and 9.1%.^1,2 The relatively minor complications include small haematomas, muscular spasms and pain. More serious complications include dissection, thrombosis, distal emboli and limb loss. We present a very rare case of a pseudoaneurysm of the sural branch of the popliteal artery following a routine popliteal PTA.

Case report

A diabetic 78-year-old woman presented with a 24-h history of severely increasing pain behind the left knee and calf, following a left popliteal PTA performed four days previously. She also described stiffness and swelling of the lower leg, affecting her ability to mobilise. The patient’s observations were within normal ranges. A full cardio-respiratory examination was unremarkable. On examination of the peripheral vascular system, the left lower leg was diffusely tender and erythematous, especially in the calf. Measurements of the left lower leg revealed a 5 cm difference in diameter compared to the right lower leg. Both lower limbs were well perfused, with a full complement of pulses bilaterally. Based on the findings, a working diagnosis of deep vein thrombosis (DVT) was considered as per the Wells criteria. ³ A full blood count, clotting profile and D-dimer were performed, all of which were unremarkable.

A venous Doppler ultrasound scan of the left lower leg was subsequently performed. This did not show a DVT. Surprisingly, a possible aneurysmal lesion within the body of the soleus muscle was visualised; however, optimal views could not be obtained due to pain. Consequently, an urgent computed tomography (CT) angiogram was performed to characterise the nature of this lesion (Figures 1 and 2). This confirmed a 4.5 cm pseudoaneurysm located in the popliteal fossa, arising 4 cm from the sural branch of the popliteal artery. OPEN IN VIEWER

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Figure 2.

Three-dimensional reconstruction of the arterial supply of the lower limbs, demonstrating the pseudoaneurysm (arrow A).

The findings were discussed with the interventional radiologists in our unit. On review of the original PTA, we discovered that the sural artery had been catheterised (Figures 3 and 4). Unfortunately, the post-procedure contrast images only viewed above and below the origin of the sural artery which otherwise would have shown contrast leakage. OPEN IN VIEWER

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Figure 4.

Inflated balloon within the popliteal artery and traversing the origin of the sural artery (arrow A), leading to unintentional catheterisation of the sural artery.

Subsequently, the patient was urgently transferred to the interventional radiology suite. The pseudoaneurysm was successfully treated endovascularly with a thrombin injection (Figure 5). Following the procedure, the patient made a full recovery with no long-term sequelae. OPEN IN VIEWER

Discussion

PTA is a well-accepted treatment option for peripheral vascular disease. However, like all procedures, it can be associated with many complications. Our case demonstrates a truly rare complication that was managed successfully. This case also highlights the anatomical and technical considerations when performing a PTA.

The popliteal artery is a continuation of the superficial femoral artery from which the two sural arteries arise at the level of the knee joint to supply the gastrocnemius, soleus and plantaris muscles. ⁴ These large branches of the popliteal artery arise inferiorly to the inferior geniculate arteries and run adjacent to the sural nerve. Occlusion of the sural arteries can lead to ischaemia and necrosis of the superficial calf muscles.

There are two previous reports of sural artery pseudoaneurysms following orthopaedic knee procedures ⁵ in the published literature. The popliteal artery is at increased risk of damage in arthroscopy due to its close relationship to the knee capsule. In these cases, obliteration was performed with coils and thrombin injection. ⁵ However, a thorough literature search revealed no previously reported cases of iatrogenic sural artery pseudoaneurysms following PTA. We therefore believe this to be the first ever reported case of sural artery pseudoaneurysm following a PTA. In addition, compared to previous reports, this case is further unique due to the mechanism of injury. Previous cases report extra-luminal trauma such as compression or blunt trauma. Our case involved iatrogenic catheterisation and then ‘intra-luminal’ puncture of the sural artery.

This case has generated key learning points for vascular surgeons and interventional radiologists, as the possibility of iatrogenic arterial injury should be suspected in patients presenting with swelling, pain or ecchymosis following a PTA. Diagnosis should be based on non-invasive imaging with colour-flow duplex and a CT angiogram.

Treatment options for pseudoaneurysm depend on the site, size, morphology and symptoms. Surgical repair, ultrasound-guided compression therapy, thrombin injection and coiling are treatment options as well as non-interventional active observation when the neck of the aneurysm is small, and there is a likelihood of spontaneous thrombosis.^6,7 In our case, the pseudoaneurysm was not amenable for compression therapy in view of the location and size. For the same reason, an interventional radiological method for embolisation was preferred over surgical treatment which would have been challenging due to the location, extensive bruising and haematoma in the lower leg.

Conclusion

Although rare, arterial injury, dissection and pseudoaneurysms after PTA at a site distal to the puncture site are recognised complications. To avoid iatrogenic injury during the procedure, screening with contrast should be performed before balloon deployment as well as following the procedure. This will ensure that the catheter has remained within the intended vessel.

Early intervention certainly reduces morbidity, which in this case could be compartment syndrome and limb loss.