NEW YORK CITY -- More physicians should screen for swelling of the artery behind the knee, an increasingly common condition that, left untreated, could lead to the loss of a leg, a prominent vascular surgeon said recently.Most patients will have successful results if the condition, popliteal artery aneurysm (PAA), is found soon enough and treated, said Enrico Ascher, MD.
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Treating a Popliteal Aneurysm
Rupture is not as common as thrombosis in PAA, so surgical repair is not always called for. Vascular surgeons sometimes perform thrombolysis (the breaking up of a clot) in the artery to improve blood flow. This can be done by infusion of a thombolytic agent like urokinase or streptokinase. This treatment, however, sometimes causes irreversible blockages further down a limb.
Surgery involves attaching a vein graft using a piece of the patient’s own saphenous vein (a secondary leg artery) to replace the weakened portion of the popliteal artery. Manmade materials such as Dacron and PTFE (polytetrafluoroethylene) are also used in some cases.
Endovascular stent grafts are beginning to be used as a minimally invasive treatment as well. A vascular surgeon pushes the stent graft through the artery using a catheter and then withdraws the catheter. This type of repair has its limitations, especially when the stent graft is placed at the level of the knee joint, where repeated flexing of the joint can cause postoperative complications.
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Left untreated it could cause severe blood vessel blockage, gangrene and amputation."We should be pretty aggressive about it," he said. "It is the most common peripheral aneurysm and we have to pay a little more attention to it."
PAA appears as a pulsating mass behind the knee, and can be detected by ultrasound, Doppler imaging, magnetic resonance angiography, computed tomography scan or arteriogram. Sometimes a patient may have pain and tenderness, but by that time there already may be a serious blockage, said Ascher, speaking at the VEITH vascular symposium held here in November. Ascher is professor of surgery at Mount Sinai School of Medicine and director, division of vascular surgery, at Maimonides Medical Center, Brooklyn, NY.
Asher told Veins1.com that 2% of males over the age of 60 have aortic aneurysms, and 15% of that group also have PAAs. Most are found by accident. "We found that very few generalists examine patients for this condition," he said.
PAAs don’t rupture as often as their life-threatening aortic counterparts, but vessel blockage, or thrombosis, is more likely, he said. Once the blood vessel closes there is very little time to save the limb.
Even a small PAA, less than or equal to 2 cm, should not be ignored and should not be considered benign, he said. In these cases there is more likelihood of thrombosis and embolism, the breaking free of blood clots that can block off smaller arteries.
Asher recommended duplex imaging, a combination of ultrasound and Doppler imaging, as a non-invasive alternative to angiography, an imaging technique that requires the injection of a dye. He said angiography often misses a clot and the dye could be harmful to kidneys. "It is important that we give attention to non-invasive screening," he told Veins1.com.
Risk factors for the condition are similar to atherosclerosis risk factors – such as smoking, type 2 diabetes or high LDL cholesterol levels, Asher said. It is more common in males and about half of patients have the condition in both legs.
With treatment in time, there could be a limb salvage rate of 94%. "It’s a very successful operation," he said.
Ascher and other vascular surgeons attending the VEITH Symposium recommended that patients with peripheral artery disease visit a vascular surgeon for a more informed diagnosis and treatment. "A lot of vascular diseases are not well served by us not being identified as an independent specialty," he said. "Once people know that we’re specialists, that we can take care of more vital things like stroke prevention, they become more aware of this."
Source: Hamsho A, Torella F, Lewis MH. Popliteal artery aneurysm – a review of management and its dilemma. Int J Surg Sci. 1999;6:21-6.
