For Referring Physicians
Newsletter

October 1999

Non-invasive Vascular Laboratory What test should I order?

Advances in Doppler color flow duplex imaging have made possible the rapid, noninvasive assessment of vascular abnormalities. The use of color flow imaging has simplified the examination, and the new generation of equipment provides intricate, direct anatomic imaging that allows physicians to make accurate and precise diagnoses.

As was stated in the last Vascular Newsletter, the Lower Extremity "arterial" Doppler study employs the measurement of pressure and flow to evaluate patients with symptoms of claudication, rest pain, ulcer/gangrene, or for follow-up of revascularization. These non-imaging, physiologic studies are adequate for localization of infrainguinal arterial occlusive disease and determination of disease severity. However, for assessment of the aorta and/or iliac arterial segments and for direct follow-up of arterial bypasses, color flow Arterial Duplex ultrasound must be employed.

Color flow Abdominal "arterial" Duplex is used to assess the abdominal aorta and iliac vessels for aneurysm, arterial stenosis, or occlusive disease. Arterial duplex ultrasound fulfills an important role in clinical practice in the initial diagnosis, treatment planning, and follow-up after intervention. This will be especially important in evaluating patients following intravascular stenting procedures. In our laboratory, infrainguinal Lower Extremity Aterial Duplex exams are reserved for bypass graft follow-up only. We feel that color flow duplex imaging is unnecessary since any patient requiring intervention will undergo an extremity angiogram.

A wide variety of vascular abnormalities can affect the upper extremities. Upper Extremity "arterial" Doppler studies are non-imaging, physiologic tests that are used to aid in the diagnostic investigation of ischemic syndromes of the arms and hands, permit vasospasm to be distinguished from arterial obstruction, help locate the site or sites of arterial obstruction, evaluate its severity, and suggest etiologies. U.E. Arterial Duplex examinations can provide direct visualization of the vessels from the level of the aortic arch to the hand. This study is directed to diagnosing atherosclerotic lesions, aneurysms, detecting complications secondary to iatragenic injury, and for evaluation of dialysis shunts.

The vascular laboratory has an established role in detecting the presence and determining the location of a deep vein thrombosis. A "Doppler of the leg" is not enough information when ordering a vascular study for the evaluation of deep vein thrombosis. Venous Duplex ultrasound is the best choice for diagnosing DVT and has all but replaced conventional ascending venography. The vascular laboratory can provide direct venous imaging of the deep or superficial veins of the legs, arms or the deep veins of the abdomen. Color flow duplex imaging allows identification of occlusive and nonocclusive venous thrombi and provides an accurate diagnosis so that appropriate treatment can be initiated.

Extracranial Carotid Artery Duplex imaging is the most common vascular laboratory study. This study provides a very accurate assessment of the extracranial carotid and vertebral arteries in patients with cerebrovascular symptoms, asymptomatic carotid bruits, following known carotid occlusive disease, or for patients who are about to undergo major cardiovascular surgery. Ultrasound makes it possible to characterize the plaque and determine the hemodynamic effect of the plaque on the extracranial circulation. The accuracy of this exam now enables carotid endarterectomy to be performed without angiography in most cases.

Over the past decade, visceral duplex evaluations including Renal Artery Duplex and Mesenteric Artery Duplex have been proven to be very accurate and reliable diagnostic tools. Renal color flow duplex imaging aids in the evaluation of patients suspected of renal artery stenosis, which may contribute to renovascular hypertension or decreased renal function. Patients suspected of mesenteric ischemia can be assessed by color flow duplex ultrasound. Many of the individuals who are studied in the vascular laboratory have problems such as pain with eating, weight loss, or other signs of arterial insufficiency. Color flow duplex allows rapid evaluation and if found to be positive, prompt intervention can be initiated.

The choice of noninvasive vascular tests should be based on the questions to be answered. These studies must be ordered with a clinically appropriate diagnosis code as found in the American Medical Association's listing, ICD-9-CM. If you or your office staff need any additional information regarding the types of studies available to you, please contact us at Apple Hill Vascular Associates, Ltd.

Thank you for your continued support!