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Carotid Artery Disease and Stroke

The Carotid arteries, located in the neck, are a major part of the blood supply of the brain. Atherosclerotic disease of these arteries may result in narrowing/constriction (stenosis), ulceration, or complete occlusion. These conditions significantly increase the risk of TIA or STROKE (permanent injury to brain tissue).

There are approximately 700,000 strokes in the United States each year, about one out of every four is related to Carotid Artery Disease. As Carotid Atherosclerosis worsen, the severity of stenosis increases and the risk of stroke increases. Plaque or accumulations of thrombus may fragment and travel (embolus) to the brain, impairing blood flow resulting in a TIA (Transient ischemic attack or “mini stroke”) or STROKE.

Risk Factors

Smoking, High Blood Pressure(hypertension), Diabetes, Hyperlipidemia (Cholesterol and Triglycerides), Heart Disease/Atrial Fibrillation, Carotid artery disease, Increasing Age, Family History, Other peripheral vascular conditions (Aortic Aneurysm, PAD), Obesity.

Symptoms and Diagnosis

Carotid Artery Disease may be suspected in the absence of symptoms by the finding of a noise in the neck heard with a stethoscope (Bruit), or simply the presence of risk factors.

The signs and symptoms of TIA and STROKE are the same, distinguished by duration and imaging. TIA lasts less than twenty four hours and is associated with negative imaging studies. A STROKE is associated with abnormalities lasting longer than twenty four hours and is usually associated with a positive imaging study. There may be:

  • Loss of vision in one eye only
  • Difficulty with speech
  • Numbness, weakness, or paralysis of one side of the body or face
  • Problems with balance or coordination

Specific diagnostic testing of the arteries themselves may include:

  • Duplex Ultrasound Examination-a non invasive test which images the artery with ultrasound and evaluates blood flow with a Doppler
  • CTA or CT Angiogram-A CAT Scan with injection of contrast material timed to image the arteries themselves
  • MRA or MR Angiogram-Magnetic resonance imaging of the vessels resulting in a “flow map”
  • Catheter Angiogram or Arteriogram-Introduction of a small tube into the arteries themselves to directly visualize the anatomy and flow channel

Imaging of the brain may be valuable to identify the actual presence of an area of infarction (stroke), or to exclude other causes for stroke-like symptoms.

Medical Treatment

Medical treatment is directed at controlling the systemic condition (Atherosclerosis): Cholesterol, Blood Pressure, Blood Sugar management, cessation of smoking, identification and management of heart disease, life style modification, and weight loss. Symptoms may be controlled with anti platelet medication (Aspirin, Clopidogrel), or anticoagulation (Heparin, Lovenox, Coumadin/Warfarin). Statins for control of cholesterol are also important stroke management medications. Reduction in the risk of Stroke or Recurrent stroke depends on treating the Plaque itself which usually occurs in the neck at the site where the Carotid artery divides into Internal and External branches.

Surgical and Endovascular Treatment

Carotid Endarterectomy (CEA) is a surgical procedure, usually done with general anesthesia, that uses an incision in the neck to directly expose the Carotid Artery, and remove the plaque in the artery. The Procedure is long established and associated with a low risk, short hospital stay, and high degree of effectiveness.

Carotid Stenting (CAS) with Embolic Protection is an endovascular procedure, in which a catheter is introduced into the artery, usually from the groin. It is done with local anesthesia and intravenous medication as needed, in an interventional suite, under fluoroscopic control. The Catheter is directed into the Carotid Artery, Radiographic imaging is performed, an embolic protection device (EPD) is introduced and a STENT is deployed which re opens the flow channel and stabilizes the plaque. The embolic protection device is intended to trap any minute particles that might be dislodged at the time of stenting. The CAS has rapidly accumulated large experience. Two recent trials have evaluated the safety and efficacy of CAS compared to CEA. Both have demonstrated a slightly higher risk of stroke with CAS. However, CAS in one study was associated with a lower incidence of heart attack either immediately after or during the procedure. Both procedures are very safe with the incidence of stroke, death or heart attack less than 6 percent    

 

Top figure is picture of carotid stent and protection device, the figures below demonstrate and angiogram of a carotid stenosis (arrow reader’s right) and angiogram following stent placement Top figure: Diagram of a carotid stent and protection device.
Bottom left: Angiogram following stent placement.
Bottom right: Angiogram of a carotid stenosis.

 

The TCAR Procedure: TransCarotid Artery Revascularization

TCAR is a clinically proven procedure combining surgical principles of neuroprotection with minimally invasive endovascular techniques to treat blockages in the carotid artery at risk of causing a stroke. A potential complication of both surgery and stenting is a stroke during the procedure itself. Studies have shown a slightly higher risk of stroke during stenting as compared to surgery. TCAR is a surgically inspired procedure and is designed to mimic the arterial access and safeguards of surgery. In carotid artery surgery, the arteries are clamped above and below the blockage to block blood flow and prevent plaque from traveling to the brain during treatment. Similarly, the ENROUTE® Transcarotid Neuroprotection System isolates the blockage from forward blood flow during stent placement by actually reversing blood flow away from the brain. Because the flow reversal method does not rely on a distally placed filter to capture emboli before they reach the brain, it collects both small and large debris. The ENROUTE® Transcarotid Stent NPS is a first in class device used to directly access the common carotid artery and initiate high rate temporary blood flow reversal to protect the brain from stroke while delivering and implanting the ENROUTE Transcarotid Stent.

CEA TCAR incision

TCAR Flow Reversal Illustration
TCAR flow reversal illustration

The TCAR procedure is performed through a small incision at your neckline just above your clavicle. This incision is much smaller than a typical CEA incision. Your surgeon will place a tube directly into your carotid artery and connect it to a system that will direct blood flow away from your brain, to protect against plaque that may come loose reaching your brain. Your blood will flow through the system and any material will be captured in a filter outside the body. Your filtered blood will then be returned through a second tube in your upper leg. After the stent is placed successfully, flow reversal is turned off and blood flow resumes in its normal direction.


* Animation and TCAR content courtesy of Silk Road Medical

When treatment is indicated the choice of procedure depends upon a number of factors including age, artery anatomy, condition of the neck, systemic illness and medical co-morbidities. Having a variety of tools in our “toolbox” permits us to advise a particular patient of the preferable procedure or permit a choice in the event of equivalence.

Conclusion

Carotid artery disease is a major cause of stroke. Both carotid endarterectomy and carotid stenting have been proven to reduce the risk of stroke in patients with significant carotid artery disease. Center specialists have extensive experience with both techniques and can provide guidance and treatment for patients who are risk for stroke.

Definitions

TIA: Symptoms similar to stroke, fully resolved within 25 hours. May include numbless and or weakness of one side of the body or face. May include difficulty with speech.

Amaurosis fugax: Loss of vision in one eye only, lasting less than 24 hours, commonly related to small embolus from Carotid Artery plaque.

Stent: A stent is a delicate metallic device which is permanently placed within a blood vessel for the purpose of stabilizing atherosclerotic plaque and re establishing a normal channel for blood flow. They are usually made of a nickel-titanium alloy and these are safe for MRI imaging

Stenosis: Narrowing or constriction of an artery. Usually expressed in terms of %. Not the same as blood flow, but severe stenosis will limit blood flow.

Plaque: A complex mixture of cells, fibrous tissue, fatty deposits, calcium and other elements, accumulating in the wall of an artery in response to the systemic condition of atherosclerosis. Can result in stenosis or occlusion, or may fragment sending particles of plaque into the blood stream.

Angioplasty (PTA-Percutaneous transluminal angioplasty):  The procedure of introducing and inflating a balloon catheter into a narrowed location of an artery for the purpose of enlarging the channel of blood flow to normal dimension. PTA fractures atherosclerotic plaque permittint the artery to enlarge or dilate. It does not remove plaque.

Endovascular procedure: Diagnostic and therapeutic procedures based on catheter guidewire technology working within the interior lumen of an artery, usually from femoral access. As distinct from open surgery where the artery is approached from the outside and opened with an incision.

Ischemia: Tissue injury from lack of blood supply, may be reversible, or may lead to infarction.

Infarct (Infarction): death of tissue resulting from lack of blood supply.

Embolic protection device: a mesh, net, filter, or occluding balloon which is placed as a barrier to emboli.

CAT Scan (CT scan): A radiographic study using X Rays to produce body images which may be reconstructed in three dimensions.

Angiogram: A general term meaning images of a blood vessel. CT can produce an angiogram image when performed with radiographic contrast material, some limitations. Magnetic Resonance (MR) may produce an “angiogram”, which is more like a “flow map”. Catheter based angiography produces a radiographic image with injection of contrast material into the artery very close to the location being studied permitting finely detailed images, an “invasive” procedure requiring needle puncture of an atery to gain access. An angiogram may image arteries in any part of the body.

Platelets: Formed elements in the circulating blood stream, representing fragments of cells that are normally present and participate in the first steps of blood coagulation (clotting)

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Email: vascular@med.usc.edu
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