CONTROVERSIES

15. Can carotid endarterectomy be performed on the basis of duplex study alone?

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The argument for elimination of arteriography in selected cases is persuasive because the carotid arteriogram alone has a morbidity rate > 1%. This rate may represent 25% of the usual total morbidity associated with carotid endarterectomy. However, to realize the benefit of surgery based on duplex ultrasound, the duplex study must have a high positive predictive value (PPV). Fortunately, the PPV is high for severe lesions that meet suitably strict criteria (e.g., peak systolic velocities > 290 cm/sec and end-diastolic velocities > 80 cm/sec).

16. Does duplex ultrasound have a role in the diagnosis of peripheral arterial disease?

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Its role is limited. Peripheral arterial disease must be assessed functionally, not anatomically. Duplex ultrasound can be used to localize disease that has already been assessed for its functional significance (exercise, not surgery, is typically prescribed for claudication alone).

17. Does transcranial Doppler have a role in the noninvasive diagnosis of cerebrovascular disease?

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No. Although the technique is widely touted, recent large studies emphasize that the Doppler evaluation of the intracranial arteries does not change the clinical management of any patient.

18. Should D-dimer blood tests be required before patients are evaluated by ultrasound for DVT?

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D-dimer is a degradation product of cross-linked fibrin. Blood plasma levels of D-dimer are often elevated in patients with DVT. However, DVT is not the only cause of elevated D-dimers and cannot be used instead of ultrasound to diagnose the presence of DVT. Conversely, in selected patient subgroups, a low D-dimer level has a very high negative predictive value and can prevent unnecessary ultrasound testing. The test should be restricted to nonsurgical patients, patients who are not anticoagulated, patients in the outpatient setting, and patients in whom there is a low clinical suspicion of DVT such as a painful limb without swelling or bilateral ankle swelling.

References
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BIBLIOGRAPHY
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5. Zierler RE, Sumner DS: Physiologic assessment of peripheral arterial occlusive disease. In Rutherford RB (ed): Vascular Surgery, 5th ed. Philadelphia, W.B. Saunders, 2000, pp 140-165.