Thrombosis of popliteal artery aneurysms can produce limb-threatening ischemia. In this setting we have found preoperative thrombolytic therapy to be beneficial. Methods: Thirty-three patients with 54 popliteal artery aneurysms were studied (mean follow-up 62 months). Twenty-one patients (62%) had bilateral popliteal artery aneurysms, and 20 patients (61%) had extrapopliteal arterial aneurysms. Thirty-three (61 %) aneurysms had symptoms of compression or ischemia, and 21 (39%) aneurysms had thrombosis. A trend toward thrombosis for larger aneurysms was noted (p < 0.068). Results: Forty-five aneurysms were treated with bypass grafting. Five-year graft patency and limb salvage rates were 71% and 90%, respectively. Factors favoring graft patency and limb salvage included presence of two-or three-vessel runoff compared with patients with single-or no-vessel runoff (p < 0.025 graft patency;p < 0.003 limb salvage) and presence of a patent aneurysm (p < 0.005 graft patency and limb salvage). Seven patients diagnosed with thrombosis of their aneurysm and all runoff vessels were treated with preoperative thrombolytic therapy. Complete clearing of thrombus from these arteries was achieved in six of these patients (and from two of these runoff vessels in the remaining patient). These patients had better graft patency (p < 0.005) and limb salvage (p < 0.01) than comparable patients treated with emergency operations. Six amputations were performed in the follow-up interval, none of which were performed in patients having undergone thrombolytic therapy. Conclusions: It is concluded that popliteal aneurysms are managed best by elective repair of patent aneurysms with good runoff. In that difficult situation of the thrombosed popliteal artery aneurysm associated with acute leg ischemia, thrombolytic therapy safely and effectively provides patients with a more favorable alternative than emergency surgery.

Background and PurposeWe compared two-dimensional time-of-flight magnetic resonance angiography (MRA) and duplex ultrasonography with arteriography for the detection of 70% to 99% stenoses at the carotid artery bifurcation (ie, surgical disease according to findings of the North American Carotid Endarterectomy Trial).Methods Three blinded readers independently measured stenoses on MRA in 73 vessels from 38 patients. Duplex ultrasonography was available in 66 vessels from 35 of these patients, and blinded reading was performed by one reader. Comparison was made to arteriography.Results Magnetic resonance angiography demonstrated a sensitivity of 92.4%, specificity of 74.5%, and negative predictive value of 95.8% for 70% to 99% stenoses. Interobserver agreement was high (K=0.91). Absence of signal at stenoses with evidence of distal flow usually, but not always, corresponded to surgical disease. Duplex ultrasonography demonstrated a sensitivity of 81.0%, specificity of 82.2%, and negative predictive value of 90.2% for surgical disease. There was

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Conscientious surveillance ofintrainguinal bypass grafts is mandatory to detect vein graft stenoses, which, ifuncorrected, can lead to graft occlusion. It is now widely accepted that noninvasive vascular laboratory studies are the best way to detect these lesions. However, controversy still exists over treatment, specifically whether balloon angioplasty is an acceptable substitute for surgery (patch angioplasty or short jump grafts) in the treatment ofthese lesions. We have always favored balloon angioplasty as primary treatment and have summarized our experience with treating 72 stenotic reversed femoropopliteal and femorotibial vein grafts, which represent 12% of 521 bypass grafts performed at our institution. Prosthetic and in situ grafts are specifically excluded from this report, as well as occluded grafts, found to have stenotic lesions after lytic therapy. The most common stenotic lesion occurred within 4 cm of the proximal anastomosis (29/72 = 40%). The other sites were near the distal anastomosis (7/72 =10%), and in the middle of the graft (15/72 =12%). Eighty-one percent (58/72) ofthe lesions were treated initially by balloon angioplasty with a 31% recurrence. Twenty-nine percent ofthe 14 grafts treated surgically by vein patch angioplasty or short jump grafts experienced recurrence. Overall 61% (44/72) of the stenotic grafts were treated by balloon angioplasty alone. The 5-year life-table assisted primary patency after correction of the stenotic lesion was 61%. The patency of the grafts from the time ofinitial bypass surgery, however, was 80%. Location ofthe stenosis within the graft was a major determinant ofpatency. Lesions in the proximal graft, proximal anastomosis, and distal graft taken as a group had significantly better patency than the midgraft and distal anastomotic lesions (5-year patency, 65% vs 48%, P < 0.001 log rank test). We continue to recommend balloon angioplasty as primary therapy for vein graft stenosis except for those occurring in the midgraft and distal "anastomosis. Fortunately, this group accounts for only 36% oflesions seen with reversed veins. Recurrent stenosis after balloon angioplasty should be repaired surgically. (J VAse SURG 1992;15:130-42).

The biochemical effects of peripheral vascular disease on skeletal muscle have not been characterized precisely because of the lack of satisfactory noninvasive analytic methods. 31P nuclear magnetic resonance (NMR) spectroscopy was used to measure the high-energy phosphate compounds, phosphocreatine (PCr) and adenosine triphosphate, as well as metabolic byproducts, such as inorganic phosphates (Pi) and phosphate monoesters in calf muscles of 214 limbs with peripheral vascular disease. Intracellular pH was also measured. The NMR index (Pi[PCr + Pi]) was used to quantitate the impairment of oxidative phosphorylation as a result of ischemia. Studies done at rest documented the impairment of oxidative metabolism only in limbs with severe ischemia (ankle-brachial pressure index (API) less than 0.4). Exercise resulted in a significant elevation of the NMR index in all limbs and the rate of return of this value toward normal following exercise was prolonged even in limbs with moderate ischemia (0.4 less than or equal to API less than or equal to 0.9). Correlation of 31P NMR parameters with arteriograms showed that infrapopliteal occlusions resulted in prolonged recovery times only when the superficial femoral artery was occluded and emphasized the metabolic consequences of multisegmental disease. Accumulation of glycolytic pathway intermediates correlated with the decrease in muscle cell pH observed with exercise. Despite immediate improvement in symptoms and hemodynamic parameters following revascularization, return to normal biochemical function occurs over a prolonged period of time. This study demonstrates that 31P NMR spectroscopy can successfully measure noninvasively the important phosphorus-containing compounds involved in the bioenergetics of skeletal muscle in vivo rapidly enough to permit real-time determination during exercise and recovery.