Popliteal Aneurysms

A common reason for acute leg ischemia is thrombosis of a popliteal aneurysm. Such aneurysms are also one of the main sources for embolization to the digits in the foot and blue toe syndrome. Besides the clinical signs of acute ischemia discussed previously, a prominent wide popliteal pulse or a mass in the popliteal fossa is often palpated when popliteal aneurysm is the reason for the obstrution.

Popliteal aneurysms are frequent in men but rare in women. They are often bilateral – more than 50% – and associated with the presence of other aneurysms. For instance, 40% of patients with popliteal aneurysms also have an aneurysm in the abdominal aorta. Most popliteal aneurysms are identified during angiography performed as part of the management process for acute leg ischemia. When an aneurysm is suspected during angiography or examination, duplex ultrasound is performed to verify the finding and estimate the aneurysm’s diameter.

If the severity of ischemia corresponds to the “immediately threatened” stage described earlier, the patient needs urgent surgery. The revascularization procedure is then often quite difficult. Exposure of the popliteal artery below the knee, including the origins of the calf arteries, should be followed by intraoperative angiography and an attempt to remove the thrombus. It is hoped that angiography can identify a spared calf artery distally. The calf arteries are sometimes slightly dilated in this patient group and can serve as a good distal landing site for a bypass excluding the aneurysm. Often, however, it is impossible to open up the distal vascular bed due to old embolic occlusions and the prognosis for the leg is poor. In such situations every possible alternative solution should be considered, including local thrombolysis, systemic prostaglandin infusion, and profundaplasty.

If the ischemia is less severe, thrombolysis may be considered following the angiography before surgical exclusion of the aneurysm. While thrombolysis previously has been considered questionable because of the risk for further fragmentation of thrombus within the popliteal aneurysm, this strategy may prove very favorable. Over the last few years several studies reporting restored calf vessels by thrombolysis have been published. This may lead to more successful bypasses and improved limb salvage. Once the bypass is accomplished good long-term results are probable. Interestingly, vein grafts used for bypasses in patients with popliteal aneurysms appear to be wider and stay patent longer than for other patient groups.

Date: 2014-12-29; view: 926