Vascular Publications

The RBCs of vascular surgery

Repair, Bypass and Chemistry of the Vascular System...
A Quarterly Publication for GPs and Health and Medical Professionals.

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CAROTID ATHEROSCLEROSIS

Part 1: Methods of Measurement (Nov/Dec 1998)
Part 2: Antiplatelet Therapy (Mar/Apr 1999)
Part 3: The Symptomatic Patient (Sept/Oct 1999)
Part 4: Asymptomatic Carotid Stenosis (Mar/Apr 2000)

ABDOMINAL AORTIC ANEURYSMS

Part 1: Pathogenisis, Diagnosis, Screening.(Sept 2000)
Part 2: Treatment. (Sept 2000)

PERIPHERAL ARTERIAL DISEASE (PAD).

Part 1: Epidemiology, Natural History, Risk Factors and Prevention. (Dec 2000)
Part 2: Clinical Evaluation and Investigation. (Mar 2001)
Part 3: Management. (June 2001)

Varicose Veins.

Part 1:Symptoms and diagnosis (Oct 2001)
Part 2:Treatment (Feb 2002)

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Repair, Bypass and Chemistry of the Vascular System... A Quarterly Publication.

CAROTID ATHEROSCLEROSIS
Part 1: Methods of Measurement

Though the prevalence of significant cervical carotid atherosclerotic disease in the elderly population is less that 10%, severe narrowing at the carotid bifurcation is clearly associated with neurological events. The benefits of medical and surgical treatment of various degrees of carotid stenosis have been debated for years. Only recently have large prospective randomised studies demonstrated the benefit of treatment for patients with significant carotid disease. The concomitant development of diagnostic imaging technology now offers the clinician several means of objectively assessing the severity of carotid disease in the process of developing appropriate patient management plans. Duplex ultrasonography and magnetic resonance angiography (MRA) have emerged alongside contrast angiography as practical methods of measuring carotid stenosis. Each method has its own particular advantages and limitations which are compared in the table below:

	Ultrasonography	MRA	Contrast Angiography
Equipment portability	mobile	fixed site	fixed site
Examination cost	low (approx. Ł50)	moderate (approx. Ł150)	high (approx. Ł700)
Operator technique dependence	high	moderate	low
Inter-observer variation in interpretation	low	moderate	moderate
Invasiveness	none	none	high
Accuracy in mild (30%) stenosis	high	moderate	high
Accuracy in moderate stenosis	moderately high	moderate	high
Accuracy in severe (>70%) stenosis	high	high	high
False-positive occlusion diagnosis rate	5% (grey scale method)	<5%	0 to 5%
Ulceration visibility	high for >2mm ulcers	poor	moderate
Extent of anatomic coverage	carotid bifurcation	carotid bifurcation to circle of Willis (aortic arch can be done)	aortic arch to cerebral vessels

Currently, Duplex Ultrasonography is the most commonly used technique, enjoying high diagnostic accuracy in the hands of skilled operators. It is an excellent tool for screening symptomatic patients, and asymptomatic patients with multiple risk factors for atherosclerosis. Continuous and pulsed Doppler techniques may be combined with transcranial Doppler blood flow information to yield highly accurate estimates of luminal diameter reduction.

If cerebral infarction or other intracranial pathology indicates the need for magnetic resonance imaging of the brain, MRA examination of the carotids may easily be added. When noninvasive study results are inconclusive or contradictory, contrast angiography is generally required to settle the diagnosis. However, angiography is not required when ultrasound and MRA studies agree on complete occlusion.

Contrast Angiography is indicated when: [1] duplex examination cannot precisely define the degree of stenosis relative to the distal carotid lummal diameter, and carotid surgery is anticipated, [2] symptomatic patients with mild to moderate carotid bifurcation stenosis have failed to improve with medical therapy, and are being considered for surgery, [3] intracranial lesions are suspected, [4] high grade stenosis cannot otherwise be differentiated from complete occlusion, and [5] vertebrobasilar symptoms are present in addition to occlusive carotid disease.

References

Mittl RL Jr, Broderick M. Carpenter JP, et al: Blinded-reader comparison of magnetic resonance angiography and duplex ultrasonography for carotid artery bifurcation stenosis. Stroke 25:4-10, 1994.

Pan XM, Saloner D, Reilly LM, Bowersox JC, Murray SP, Anderson CM, Gooding GA, Rapp JH: Assessment of carotid artery stenosis by ultrasonography, conventional angtiography, and magnetic resonance angiography: correlation with ex vivo measurement of plaque stenosis. Jour Vasc Surg. 21(1) 82-8, discussion 88-9, 1995 Jan.

Wassennan BA, Haacke em, Li D: Carotid Plaque formation and its evaluation with angiography, ultrasound, and MR angiography. [Review]. Jour Magnetic Res Imag. 4(4):5 15-27, 1994 Jul-Aug.

Toole JF, Castaldo Je: Accurate measurement of carotid stenosis, Chaos in methodology: Jour of Neuroimaging. 4(4):222-30, 1994 Oct.

Mattos MA, Hodgson KJ, Faught WE, Mansour A, Barkmeier LD, Ramsey DE, Sumner DS: Carotid endarterectomy without angiography: is co1or-flow duplex scanning sufficient: Surgery. 1 16(4):776-82, discussion 782-3, 1994 Oct.

Neale ML, Chambers JL, Kelly AT, Connard 5, Lawton MA, Roche J, Appleberg M: Reappraisal of duplex criteria to assess significant carotid stenosis with special reference to reports from the North American Symptomatic Carotid Endarterectomy Trial and the European Carotid Surgeiy Trial. Jour Vase Surg. 20(4):642-9, 1994 Oct.

Faught WE, Mattos MA, Van Bemmelen PS, Hodgson KJ, Barkmeier LD, Ramsey DE, Sumner DS: Color-flow duplex scanning of carotid arteries: new velocity criteria based on receiver operator characteristic analysis for threshold stenoses used in the symptomatic and asymptomatic carotid trials: Jour Vase Surg. 1 9(5):8 1 8-27;discussion 827-8, 1994 May.

Antiplatelet Therapy & Carotid Atherosclerosis

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