CAROTID ARTERY STENOSIS

CAROTID STENOSISDR.SRIRAMA ANJANEYULU

Carotid artery stenosis refers to pathologic atherosclerotic narrowing of the extracranial carotid arteries.
While one might expect that the amount of narrowing of the carotid artery that constitutes a diagnosis of carotid artery stenosis is correlated to the stroke risk, this relationship has not been clearly demonstrated.
The risk is difficult to determine, and consequently CAS is variably defined.
More recent RCTs evaluating the benefit of CEA defined CAS as 60-99% (i.e., ACAS, ACST) while earlier RCTs used 50-99%.
Definition

ANATOMY

ICA stenosis accounts 30% of ischemic strokes.
4-8% of 50-79 yrs old patients have ICA stenosis of >50%.
Approximately 0.5% of people in their 50s and about 10% of those over age 80 have carotid artery stenosis > 50%
2-5% annual ipsilateral stroke risk for people with ICA stenosis of greater than 50% diameter reduction.
Causes –TIA , embolic strokes.
ICA stenosis

Symptomatic
Asymptomatic
CAS

Absolute risk reduction 1.2%/yr
Perioperative complications 2.3%,death-0.1%
CEA not beneficial to women with stenosis of 60-99%.
No incremental benefit for higher stenosis-60-69% has higher reduction than 80-89%.
Limitations of ACAS

Two methods are used to screen for carotid artery stenosis:
clinical auscultation for carotid bruits
noninvasive studies of the carotid arteries.
screening

Imperfect screening test for carotid artery stenosis .
Considerable inter-observer variation among clinicians in the interpretation of the intensity, pitch, and duration of the bruit heard .
A cervical bruit can be heard in 4% of the population over age 40, but the finding is not specific for significant carotid artery stenosis .
Between 40% and 75% of arteries with bruits do not have significant compromise in blood flow .
Bruit can be produced by anatomic variation, tortuosity, venous hum, goiter, and transmitted cardiac murmurs .
Hemodynamically significant stenotic lesions may exist in the absence of an audible bruit .
Using 70-99% stenosis on carotid angiogram as a reference standard, auscultation of a carotid bruit has been found to have a sensitivity of only 63-76% and specificity of only 61-76% for clinically significant stenosis .
The positive predictive value (PPV) for auscultation of a carotid bruit has been found to beonly 34% .
Neck auscultation

Patients with cervical bruits, can be evaluated further with greater accuracy by noninvasive study of the carotid arteries.
Duplex ultrasound combines the capabilities of B-mode and Doppler ultrasound .
Compared with carotid contrast angiography (the reference standard), carotid duplex ultrasound has a sensitivity of 96% and specificity of 66% .
Depending on the underlying population characteristics, the PPV of duplex ultrasound ranges from 82% to 97% .
Magnetic resonance arteriography (MRA) is a newer imaging technique, which provides 100% sensitivity and 76% specificity compared with contrast angiography .
However, MRA is costly which precludes using it as a screening modality.
INVESTIGATIONS

Screening with duplex ultrasound in the primary care setting may be an effective way to reduce morbidity and mortality from stroke.
Statistically, the patients most likely to benefit from screening are men over the age 60 who have other risk factors for stroke, no contraindications to major surgery, and access to highquality vascular surgeons .
DUPLEX SCREENING

TIA
IS
Secondary prevention

High-resolution CE-MRA with centric space filling shows excellent correlation with DSA, offers the benefits of unlimited views and imaging of the arterial circulation from the aortic arch to the circle of Willis, and is almost noninvasive.
It has the potential to replace DSA in the detection of degree of stenosis, vessel occlusion and plaque ulceration. CE-MRA has largely replaced conventional DSA for the investigation of cerebrovascular disease in most centres, but DSA continues to be used in unclear cases.
MayankGoyal, MD; Julie Nicol, MD; Dheeraj Gandhi, MD Can Assoc Radiol J 2004;55(2):111-9.
DSA VS MRA

DSA,CEMRA

DSA,MRA

Distal protection devices such as FilterWire EX have been widely used in carotid artery stenting to prevent distal embolization of plaque debris
Seung Hwan Han, WoongCholKang,TaeHoonAhn, and EakKyun Shin J Korean Med Sci 2009; 24: 967-9
Filter devices in CEA

Stenting and Angioplasty with Protection in Patients At High Risk for Endarterectomy (SAPPHIRE) was the first randomized study comparing endarterectomy and stenting in highrisk patients.
The study revealed that the incidence of cerebral strokes and deaths in the perioperative period and after one year follow-up did not differ statistically after CEA and CAS (8.4% CEA vs 5.5% CAS p = 0.36), however, carotid stenting was associated with lower rate of heart infarcts in the perioperative period.
Bell indicates that this trail was flawed for several reasons i.e. it was commercially funded, it favoured CAS by considering a biochemical myocardial event as an end point.
specific patient subgroups, with significant medical comorbidities, recurrent stenosis, anatomically inaccessible lesions and a hostile neck might benefit from CAS.
CEA VS CAS

Pomegranate juice consumption for 3 years by patients with carotid artery stenosis reduces common carotid intima-media thickness, blood pressure and LDL oxidation.
Michael Aviramaetal,
Clinical Nutrition (2004) 23, 423–433.
Antioxidants-CAS

CAROTID ARTERY STENOSIS

by Srirama Anjaneyulu on Jul 07, 2010

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