Noninvasive VascularD iagnostic Laboratory. Controversies
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).
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Noninvasive Vascular Diagnostic Laboratory. Peripheral Arterial Occlusive Disease
PERIPHERAL ARTERIAL OCCLUSIVE DISEASE
11. What is the primary test for diagnosis of lower extremity ischemia?
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The ankle brachial index (ABI) or systolic pressure ratio is normally greater than or equal to 1.0. Typically, Doppler ultrasound is used (instead of a stethoscope) as the flow sensor distal to the pressure cuff, but plethysmographic instruments also may be used. Doppler signals are usually monitored at the posterior tibial artery or dorsalis pedis artery.
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Noninvasive Vascular Diagnostic Laboratory. Venous Disease
VENOUS DISEASE
7. What noninvasive test is used to diagnose acute DVT?
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Duplex ultrasound has replaced venous occlusion plethysmography as the accepted standard. Colorflow duplex is useful because it helps to identify small veins from the muscle and fascial layers. The ultrasound assessment involves the following steps:
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Noninvasive Vascular Diagnostic Laboratory. Cerebrovascular Disease
CEREBROVASCULAR DISEASE
3. Which noninvasive tests should be used to diagnose extracranial carotid artery disease?
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Duplex ultrasound has a sensitivity of 97% in detecting carotid artery disease and an accuracy of 95% in correctly classifying carotid stenoses as > 50% reduction in diameter. No other noninvasive test has comparable accuracy.
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Noninvasive Vascular Diagnostic Laboratory
73 NONINVASIVE VASCULAR DIAGNOSTIC LABORATORY
Darrell N. Jones Ph.D.
1. What is the role of the vascular diagnostic laboratory (VDL) in the assessment and treatment of patients with suspected vascular disease?
Venous Disease
72 VENOUS DISEASE
Thomas A. Whitehill M.D., Mark Nehler M.D.
1. Where does deep venous thrombosis (DVT) originate?
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More than 95% of DVTs develop in the deep veins of the lower extremities; the majority originate in the valve sinuses of the calf veins.
2. What is the usual source of a pulmonary embolus?
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Calf vein thrombosis may propagate proximally into the deep venous system to involve the popliteal, femoral, or iliac veins (or a combination of veins). These proximal DVTs are the culprits in > 90% of pulmonary emboli.
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Abdominal Aortic Aneurysm
71 ABDOMINAL AORTIC ANEURYSM
Mark Nehler M.D., William C. Krupski M.D.
1. What is an abdominal aortic aneurysm (AAA)?
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A ≥ 50% increase in normal aortic diameter. Normal infrarenal aortic diameter is 2.0 cm for men. A definition of AAA as an aorta ≥ 3.0 cm in diameter is appropriate.
2. What is the incidence of AAA?
Abdominal Aortic Controversy
CONTROVERSY
29. What is the role of CEA?
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Although CEA remains the standard of care for carotid artery disease, percutaneous angioplasty with stenting has been investigated as an alternative. The underlying rationale is to decrease morbidity, hospital costs, and anesthetic risks and to improve long-term patency. Reported rates of success, morbidity, and mortality run the gamut from stroke and death rates comparable to CEA (2.4%) to significantly higher neurologic risk (stroke rate, 8.8%) and higher cost. One randomized trial is currently under way in Great Britain, and applications for two other studies are being considered in the United States. Carotid angioplasty has no apparent benefit compared with CEA.
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CAROTID DISEASE
70 CAROTID DISEASE
Rao Gutta M.D., B. Timothy Baxter M.D.
1. What diseases affect the carotid arteries?
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Atherosclerosis is by far the most common (accounting for 90% of lesions in the Western world). The carotid also can be affected by fibromuscular dysplasia, inflammatory arteriopathies (e.g., Takayasu’s arteritis), extrinsic compression (e.g., neoplasm), and trauma.
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ARTERIAL INSUFFICIENCY
69 ARTERIAL INSUFFICIENCY
Mark Nehler M.D., William C. Krupski M.D.
1. Describe claudication and its physiology.
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Intermittent claudication consists of reproducible lower extremity muscular pain induced by exercise and relieved by short periods of rest. It is caused by arterial obstruction to affected muscular beds, which restricts the normal exercise-induced increase in blood flow, producing transient muscle ischemia. Studies have shown that more than half of patients with intermittent claudication have never complained of this symptom to their physicians, assuming that difficulty with walking is a normal consequence of aging.
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What Is Atherosclerosis
68 WHAT IS ATHEROSCLEROSIS?
Craig H. Selzman M.D.
1. Are elderly individuals the only ones who have atherosclerosis?
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No. The initial (or type I) lesion, consisting of lipid deposits in the intima, has been well characterized in infants and children.
2. What is a fatty streak?
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Fatty streaks or type II lesions are visible as yellow-colored streaks, patches, or spots on the intimal surface of arteries. Microscopically, they are characterized by the intracellular accumulation of lipid.
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Abernathy’s Surgical Secrets, Updated Edition (Book w / Student Consult)
Author / s: Harken Alden H., Abernathy Charles, Moore Ernest Eugene
Year: 2004
Pages: 473
Publishers: Elsevier Mosby; 5th Bk & Acc edition
ISBN: 0323034160
