Carotid artery stenosis

There is no benefit for routine screening of populations with no clinical manifestations or risk factors for atherosclerosis.

The attributable risk of carotid artery stenosis for stroke in those older than 60 years of age is 0.9%.

In a symptomatic individuals between a 40-54 years almost 1/3rd have ultrasound evidence of atherosclerosis in the carotid arteries.

There is no validated risk stratification tool or physical findings, including the presence of the cervical bruit that is useful to identify those who do or do not have clinically important asymptomatic carotid artery stenosis.

When atherosclerosis become severe enough in the carotid artery to cause stenosis, it may be a source of embolism and, by extension because ischemic stroke.

When cerebral infarction or reversible cerebral ischemia occurs distal to carotid stenosis, carotid stenosis is symptomatic.

The risk of future stroke increases with greater degree of stenosis in patients whose stenosis is symptomatic.

In a study of 3737 participants with 70 to 99% asymptomatic carotid stenosis followed for five years the estimated rate of ipsilateral carotid related acute ischemic stroke was 4.7% (Chang RW).

Anterior cervical bruit is an indicator of generalized atherosclerosis and is a greater risk factor for death due to coronary heart disease than stroke.

Causes about 10-20% of all ischemic strokes and transient ischemic attacks.

Appropriate intervention is important for secondary and possibly primary stroke prevention.

Degree of stenosis is the strongest determinant of stroke risk.

Atherosclerosis is the most common disease affecting the carotid artery and occurs most frequently at the bifurcation.

Carotid atherosclerotic plaques cause symptoms by distal embolism to branches of the cerebral arteries including the retinal artery.

In patients with carotid artery plaque in which micro plastics and nano plastics(MNPs) were detected, had a higher risk of myocardial infarction, stroke, or death from any cause at 34 months of follow up than those in whomMNP’s were not detected (Marfella R).

Hemodynamically significant stenosis of carotid artery lumen may result in reduction of vascular perfusion.

Internal carotid artery occlusion causes approximately 10% if TIAs and 15-25% of ischemic strokes in the carotid distribution.

Prevalence of asymptomatic carotid artery disease of at least 50% occurs in 4.2% of the general population, increasing with age to 7% of women and 12% of men older than seventy years.

CAS is it usually asymptomatic and its first manifestations are frequently TIAs or stroke.

Asymptomatic internal carotid artery stenosis develops in 7-9% of patients by 75 years.

There is a higher risk of five-year carotid territory artery stroke in individuals with stenosis of 70% narrowing, severe stenosis, a degree present in only 0.5-1% of US cohorts.

1-2% age 65-84 will have sufficiently severe asymptomatic internal carotid artery stenosis to consider carotid artery revascularization.

The 2 year risk of subsequent ipsilateral ischemic stroke in patients with internal artery occlusion while a patient receives medical therapy is 10-15%.

Clinical separation between symptomatic and asymptomatic stenosis is required.

Most embolic phenomenon from carotid arteries result from activation platelets on plaques and less frequently from cholesterol particles.

A patient is considered symptomatic, if the patient has had a transient or permanent neurologic symptoms related to the ipsilateral retina or cerebral hemisphere.

Symptoms include: ipsilateral transient visual disturbance, known as amaurosis fugax, from retinal ischemia, contralateral weakness or numbness of an arm, legs, face, or any combination of these sites, visual field defect, dysarthia, and dominant hemisphere involvement with a aphasia.

Most patients with carotid artery stenosis never have symptoms, but some may be at risk of stroke.

While clinically many patients present with weakness, dizziness, syncope, blurred vision, near syncope, transient positive visual phenomenon, such as floaters, they are nonspecific symptoms, and are not necessarily symptomatic ischemic events and are therefore not considered symptomatic, even in the presence of severe carotid stenosis.

Quantification of the degree of stenosis is essential to select proper treatment, and this process is particularly important for patients who are asymptomatic, because of the marginal benefit they receive from surgery.

Ultrasound is the first diagnostic imaging tool and is used to screen for carotid artery stenosis.

Doppler ultrasound has a sensitivity of 86% and a specificity of 87% for the detection of hemodynamic significant stenosis (Nederkoorn PI).

Angiography is the standard procedure for determining the degree of stenosis and morphologic features of the plaque.

CT angiography, and magnetic resonance angiography have replaced conventional catheter angiography in many cases.

Invasive treatment is considered for symptomatic patients with stenosis of greater than 50% and for asymptomatic patients with stenosis of greater than 60%.

Patients with 50% stenosis of the carotid artery and symptoms or patients with no symptoms but 70% stenosis may be considered for surgery.

Carotid orderly solution suspected by ultrasound study was confirmed with noninvasive or invasive angiography, especially in patients with symptoms.

Occluded carotid arteries should not be subject to invasive therapies.

Recurrent stroke within 2 years following a stroke is 20% if medically treated.

Women with carotid artery stenosis less likely to have evidence of coronary artery disease, more likely to have hypertension, and have a significantly greater risk of diabetes than men with carotid disease.

Atherosclerotic lesions may fracture and cause an intrauminal thrombus resulting in an embolism to the brain.

Lowering the risk of stroke in patients with carotid artery stenosis includes management with antiplatelet agents and other drugs to treat factors associated with accelerated atherosclerosis including hypertension, diabetes, and hyperlipidemia.

Stopping smoking is an important management in this process.

Nearly half of patients with either symptomatic or asymptomatic carotid disease have coexisting coronary artery disease.

Endarterectomy for asymptomatic stenosis greater than 60% reduces the 5-year ipsilateral stroke rate from 11% to 5%.

Endarterectomy preferred over angioplasty.

In patients  that have had previous carotid surgery or radiation on the neck or have severe cardiac of pulmonary disease, or if the plaque is in a difficult place, surgery may not be feasible or safe, and these cases endovascular carotid artery stents may be used.

Among patients undergoing management for carotid stenosis, transcarotid artery vascularization, compared with transfemoral carotid artery stenting, is significantly associated with a lower risk of stroke or death (Schermerhorn ML).

With a stenosis in the range of 90-94%, there is a 35% risk of stroke at 1 year for medically treated patients compared with an 8.7% risk for those treated with carotid endarterectomy.

Endovascular treatment has similar results for major risks and effectiveness at prevention of stroke during 3 year follow-up compared with carotid surgery.

In carotid artery stenting a small basket is placed past disease there are you to catch any plaque that may break off during the procedure to minimize risk of stroke.

Carotid Revascularization Endarterectomy vs Stenting (CREST): Stenting was safe, and effective in preventing stroke, myocardial infarction, or death as carotid endarterectomy.CREST study randomized 2502 individuals with asymptomatic and symptomatic carotid artery disease to endarterectomy or stenting: within 30 days 2.3% of surgical patients and 4.1% of stented patients had a stroke, while 2.3% of surgical patients and 1.1% of stented patients had a myocardial infarction.

CREST was not associated with a significant reduction in MI by stenting and the increase in stroke was more devastating due to its detrimental effect on quality of life.

CREST study: patients less than 69 years did slightly better with stents, and those over age 69 did slightly better with surgery.

A stent allows blood to flow through.

CREST Study is the largest trial comparing carotid endarterectomy and carotid angioplasty and stenting.

CREST Study associated with the lowest rate of perioperative complications of any recent trials.

In a randomized study of symptomatic and asymptomatic patients with carotid stenosis to stenting or carotid endarterectomy: 2502 patients followed for 2.5 years the risk of stroke, myocardial infarction, or death did not differ (Carotid Revascularization Endarterectomy vs Stenting Trial (CREST)).

CREST trial above, the 4 year rate of stroke or death was 6.4% with stenting and 4.7% for endarterectomy group and the rates among symptomatic patients were 8% vs 6.4%, and the rate for asymptomatic patients was 4.5% vs 2.7%.

In the CREST trial above, the periprocedural period associated with a higher risk of stroke for the stenting group and a higher risk of myocardial infarction than with endarterectomy.

A meta-analysis including the Carotid Revascularization Endarterectomy vs Stenting Trial (CREST), International Carotid Stenting Study (ICSS), ans Stent Protected Angioplasty versus Carotid Endarterectomy (SPACE) have concluded stenting compared with CAE increased the risk of stroke (Murah MH et al).

The International Carotid Stenting Study (ICSS) compared endarterectomy and carotid artery stenting found surgery to be superior.

The ICSS study randomized 1713 with symptomatic carotid artery stenosis to endarterectomy or stenting: at 120 days the absolute risk of stroke, myocardial infarction, or death was 8.5% for the stented group and 5.2% for the endarterectomy group.

Carotid stenting has rapidly increased in frequency and approximately 70-90% of placements are in asymptomatic patients.

The ICSS study indicated that risks for any stroke, and all cause death higher for endarterectomy group.

The majority of carotid stenting in the United States is performed by cardiologists, followed by surgeons and then radiologists.

Guidelines on extracranial carotid disease for carotid artery endarterectomy is reasonable in asymptomatic patients who have more than 70% stenosis of the internal carotid artery if the risk of perioperative stroke, myocardial infarction and death is low.

Extracranial-intracranial arterial bypass surgery to prevent stroke by improving hemodynamics distal to the occluded artery does not reduce the risk of recurrent ipsilateral ischemic stroke at 2 years compared to medical therapy (The Carotid Occlusion Surgery Study Randomized Trial).

Guidelines recommend consideration of prophylactic carotid artery stenting in selected patients with asymptomatic internal carotid artery stenosis with 60% minimum by angiography, 70% by Doppler ultrasound, but efficacy compared with medical therapy alone is not well established.

Patients with carotid artery stenosis of greater than 70% have a five year stroke risk of approximally 5%.

Reviews and meta-analyses demonstrate no studies providing information suggesting screening for carotid stenosis reduces stroke.

Age modifies the treatment difference between patients treated with carotid stunting and those with carotid endarterectomy.

Randomized controlled studies reveal carotid endarterectomy is superior to carotid artery stenting in patients aged 70-74 years and older.

In the above studies the difference in older patients is almost fully attributed to increasing periprocedural stroke risk in patients treated with carotid artery stenting.

Age has little effect on carotid endarterectomy periprocedural risk or on postprocedural risk after either procedure.

A trans carotid artery revascularization procedure may reduce the risk of strokes.
During trans carotid artery revascularization a small incision is made in the nick to access the carotid artery directly.
During this trans carotid artery revascularization a device is connected to blood vessels to reverse blood flow during the procedure so debris or fragments of plaque are carried away from the brain rather than toward it.
A stent is subsequently placed in the carotid artery and the flow reversal device is removed. 
The risk of stroke with this procedure is similar to that to open surgery, approximately 2%, but lower than with carotid artery stenting at about 4%.

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