Abstract
Background
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.
Purpose
To determine the ability of duplex scanning to differentiate embolic from thrombotic acute arterial occlusion.
Methods
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.
Results
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).
Conclusion
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.
1
Introduction
Acute limb ischemia (ALI) denotes a sudden reduction in limb perfusion, usually producing new or worsening symptoms and signs and often threatening limb viability . In the whole population, acute ischemia of limbs happens in 14 cases per 100,000 inhabitants .
ALI is usually caused by atherosclerotic disease but can also arise from nonatherosclerotic causes (e.g., arteritis, dissection, etc.); however, the most important causes are either embolic or thrombotic occlusion.
Management of ALI is largely based on the etiology of arterial occlusion (embolic vs. thrombotic). Outcomes and prognosis of ALI largely depend on the rapid diagnosis and initiation of appropriate and effective therapy .
It is often difficult to distinguish an embolus from a thrombosis, but embolic occlusions are usually suspected in patients with acute onset or with previous history of embolization; however, thrombosis can be dramatically sudden and emboli can be silent particularly in obtunded or sleeping patients.
Arteriography often allows a distinction to be made between embolus and thrombus; however, the fear of contrast media harming an acutely ischemic leg, causing renal damage, allergy with risk of vascular complications from invasive procedure, and the delay in performing formal angiography represent the major drawbacks of arteriography in ALI, where rapid and accurate diagnosis is essential for saving the ischemic limb .
Many previous studies proposed that duplex scanning can replace effectively preoperative contrast angiography and to be the sole preoperative imaging in the setting of chronic limb ischemia ; however, to the best of our knowledge, the ability of duplex scanning to differentiate embolic from thrombotic acute arterial occlusion has not been properly evaluated or reported .
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