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Radiology
Popliteal aneurysms: Endovascular Management
Case 34: Contributed by Dr. Nikhil Karnik
Case 1
A 65-year-old male presented with history of swelling behind the right knee and difficulty in walking of one month’s duration. There was no history of trophic changes in the leg. His general examination was normal. On local examination, mild fullness of popliteal fossa was seen.A color Doppler examination of the right leg showed atherosclerotic changes in the leg vessels with a 3 cm x 4 cm aneurysm arising from the right popliteal artery.
Selective angiogram of the right lower limb showed a saccular aneurysm arising from the medial wall of the popliteal artery. The right leg showed good three vessel distal run off. (Fig 1 & 2).
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Fig 1 |
Fig 2 |
Endovascular treatment was planned, to exclude the aneurysm from the popliteal artery. Through a 8 Fr., left transfemoral access, a Balkin sheath was placed in the right external iliac artery. After approximate caliberation of the size of the stent (fig 3) , the lesion was negotiated using a 0.018” “Stabilizer “ wire after obtaining a road map.
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Fig 3 |
The catheter was then advanced over the wire across the lesion after which the “Stabilizer” wire was exchanged with a stiffer wire. A stent graft was placed and deployed across the aneurysm. Thereafter balloon dilatation of the stent graft was done using 6 x 40 mm balloon angioplasty catheter (fig 4).
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Fig 4 |
The post-procedure angiogram revealed complete exclusion of the aneurysm from the circulation with a good three vessel distal runoff in the leg. (Fig 5)
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Fig 5 |
Case 2
A 45-year-old female patient, non diabetic non hypertensive, with a history of road traffic accident with trauma to the right leg a few months back, presented with a swelling in the right popliteal fossa gradually increasing in size since two months. There was mild pain associated with the swelling and difficulty in walking. On general examination, the patient was febrile and on local examination, the swelling was tender with the overlying skin showing inflammatory change. On colour Doppler there was a fairly large pseudoaneurysm seen arising from the popliteal artery extending inferiorly to involve its bifurcation and the proximal right anterior tibial artery.
A selective right lower limb angiogram revealed a fairly large saccular pseudoaneurysm with a wide neck arising from the right popliteal artery.. Theer was immediate occlusion extending into distal popliteal, its bifurcation and origins of leg branches. (figure 6,7) with reformation of the leg braches in distal calf through multiple collaterals and three vessel distal runoff in the leg.
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Fig 6 |
Fig 7 |
Endovascular treatment was planned for this lesion with the aim of excluding it from the circulation while maintaining the distal runoff in the calf and leg. After a selective angiogram using a 5 Fr. head-hunter catheter via a left transfemoral access, the catheter was advanced into the distal most portion of the native popliteal artery just proximal to the mouth of the pseudoaneurysm (figure 6 and 7). Proximal popliteal artery embolisation was decided as there was no patent popliteal artery distally to consider stentgraft placement & surgery was defered as this was tense swelling with inflammatory changes in the region secondary to infection. Two coils of 38-5-5 and 35-5-5 size were placed in the native popliteal artery with the aim of occluding it (figure 8 and 9).
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Fig 8 |
Fig 9 |
The post procedure angiogram revealed complete occlusion of the native right popliteal artery, complete exclusion of the pseudoaneurysm from circulation and a good distal reformation of the calf arteries through multiple collaterals.(figure 10,11).
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Fig 10 |
Fig 11 |
On clinical and imaging follow up after one week, there was remarkable reduction in size of swelling with no signs of arterial insufficiency.
DISCUSSION:
Aneurysms can be categorized as either true or false. True aneurysms occur when all layers of the arterial wall are abnormally dilated. False aneurysms (pseudoaneurysms) are due to a defect in the arterial wall related to trauma or (mycotic) infection. Under the influence of sustained arterial pressure, blood dissects into the tissues around the damaged artery and forms a perfused sac, which communicates with the arterial lumen; The perfused sac is lined by the media and the adventitia or simply by the soft tissue structures surrounding the damaged artery.
The popliteal artery is considered to be aneurismal when it measures more than 7mm in diameter. True aneurysms of the popliteal artery are the most common peripheral arterial aneurysms. Almost all true aneurysms are non specific. Historically, the nonspecific form of aneurysmal disease that affects the abdominal aorta and the iliac, femoral and popliteal arteries has been described as “atherosclerotic.” Less commonly they may be associated with connective tissue diseases like Marfan’s and Ehlers-Danlos syndrome. Popliteal artery aneurysms are often associated with aneurysms at other locations like the abdominal aorta and the contralateral popliteal artery.
Although popliteal artery aneurysms may be asymptomatic in as much as 45% of patients, they present with symptoms of lower limb ischemia like claudication , rest pain, non healing ulcers or distal embolic occlusion. Though the advent of non invasive diagnostic modalities has increased the sensitivity for diagnosis of asymptomatic disease, conventional angiography remains the standard of reference for diagnosis. The significant advantage of angiography is real time haemodynamic assessment of a vascular bed, which includes identifying collaterals and assessing the expendability of the donor artery, which plays an important role in treatment planning.
Endoluminal management serves to exclude an aneurysm from the circulation. Selecting the optimal method depends on the size of the aneurysmal neck and the expendability of the donor artery .Exclusion methods fall into two broad categories: embolization and stentgraft placement. A pseudoaneurysm that arises from an expendable donor artery is treated with emblisation of the parent artery. A pseudoaneurysm arising from an inexpendable parent artery must be excluded from the circulation while preserving the donor artery. Another important determinant used in management is the width of the pseudoaneurysm neck relative to the diameter of the donor artery. Narrow necked pseudoaneurysms are treated with catheter based delivery of coils into the sac itself. A potential disadvantage of using coils is the potential for recanalization if the embolised sac not been tightly packed. Wide necked pseudoaneurysms are treated with either stentgraft placement across the lesion to exclude it from circulation. Stentgrafts are generally contraindicated in mycotic aneurysms due to the potential risk of stentgraft infection. Another method often used is stent or ballon assisted embolization of the aneurysm sac.
In conclusion, the use of endovascular methods in the treatment of aneurysms have encouraging results and are effective, minimally invasive techniques that can be used for definitive treatment of these lesions.