Value of duplex scanning in differentiating embolic from thrombotic arterial occlusion in acute limb ischemia

Management of acute limb ischemia (ALI) is largely based on the etiology of arterial occlusion (embolic vs. thrombotic). To our knowledge, the ability of duplex scanning to differentiate embolic from thrombotic occlusion has not been previously reported.

To determine the ability of duplex scanning to differentiate embolic from thrombotic acute arterial occlusion.

We prospectively recruited 97 patients (50.3 ± 19.7 years; 55% males) with 107 nontraumatic ALI in native arteries. All patients underwent surgical revascularization. Preoperative duplex scan detected arterial occlusion in the following arteries: iliac (11), femoral (38), popliteal (38), infrapopliteal (3), subclavian (3), axillary (1), brachial (9), and forearm arteries (4). We measured the arterial diameters at the site of occlusion (d(occl)) and at the corresponding contralateral healthy side (d(CONTRA)). The difference (Δ) between the two diameters was calculated as d(OCCL)-d(CONTRA). Duplex scan was also used to assess the state of the arterial wall whether healthy or atherosclerotic and the presence of calcification or collaterals. According to surgical findings, limbs were classified into embolic (E group=55 limbs) and thrombotic (T group=52 limbs) groups.

Both groups were comparable regarding age, diabetes, hypertension, smoking, atrial fibrillation, and time of presentation. The status of arterial wall at the site of occlusion and presence of calcification or collaterals were all similar in both groups. Δ in the E group was 0.95 ± 0.92 mm vs. -0.13 ± 1.02 mm in the T group (P<.001). A value of ≥ 0.5 mm for Δ had 85% sensitivity and 76% specificity for the diagnosis of embolic occlusion (CI 0.72-0.90, P<.001), whereas a value of less than -0.5 mm for Δ had 85% sensitivity and 76% specificity for thrombotic occlusion (CI 0.72-0.90, P<.001).

In acute arterial occlusion, ≥ 0.5 mm dilatation or diminution in the occluded artery diameter is a useful duplex sign for diagnosing embolic or thrombotic occlusion, respectively.