Carotid Arterial Disease
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CAROTID ARTERY DISEASE
The carotid arteries are major blood vessels that lie deep in the neck on both sides of the windpipe. They carry blood from the heart to the brain and other parts of the head.
Normal carotid arteries are smooth inside but as people age the carotid arteries can become diseased due to build up of a fatty substance called plaque. This process is called atherosclerosis or “hardening of the arteries”. The narrowing caused by plaque is called a stenosis.
Plaque can severely obstruct blood flow in the arteries. In carotid arteries that require surgical removal of plaque, the blood flow is often reduced by two-thirds. In severe cases, blood flow can be reduced to a trickle. Ulcers can form on the surface of the plaque. Small blood clots can form on the ulcers. These clots and small particles of plaque can dislodge and travel up into the brain, causing a stroke.
A stroke occurs when blood stops flowing to a part of the brain due to a blockage in an artery. When interruption of blood flow is severe and lasts for more than a few minutes, brain cells will die. Disabling stroke occurs when larger areas of brain are deprived of blood flow. If a less important region of the brain is affected, the stroke will be less disabling. A stroke that affects an important part of the brain can be life threatening.
In some patients, surgical treatment to remove the plaque may be effective in reducing the risk of stroke. The surgical options are:
- carotid endarterectomy
- carotid angioplasty with stent
Although large clinical studies have confirmed that carotid endarterectomy and angioplasty with stenting have significant benefits in well selected patients, the procedure does have risks.
SYMPTOMS
Transient Ischaemic Attack (TIA), (“mini stroke”) or Stroke
A blood clot or piece of plaque can cause a transient stroke by a temporary blockage of blood supply to a part of the brain. A TIA is an important indication that the risk of stroke in the near future is high. The symptoms are usually brief, lasting from a few minutes to a few hours, a stroke results if symptoms last longer than 24 hours. Symptoms may include:
- weakness, numbness or poor coordination on one side of the body, affecting an arm, leg, face or mouth
- garbled or slurred speech
- difficulty understanding spoken words
- difficulty reading and disturbances to vision, particularly temporary loss of vision in one eye (amarosis fugax)
DIAGNOSIS OF ARTERY DISEASE
Accurate diagnosis will greatly assist your doctor in planning the treatment. By knowing the amount of stenosis, your doctor can assess the risk of stroke on that side of the brain. Special tests can reveal whether a carotid artery is severely diseased. The following techniques are most commonly used to diagnose the condition of the carotid arteries. Each has its advantages and disadvantages.
Ultrasound
This is usually the first test given to a patient with a suspected stenosis or occlusion. A probe similar to a microphone is placed on the patient’s neck over the carotid arteries. Abnormal blood flow in the carotid arteries can be detected and images of stenosis can be displayed on a video screen.
Magnetic Resonance Angiography (MRA)
MRA provides images of the carotid arteries and the direction and velocity of blood flow. The patient lies still while computerised pictures are made of the neck.
Spiral Computed Tomography
Often called CT angiography, this technique produces three-dimensional images of the stenosis. It relies on a special dye injected into a vein.
Carotid Angiography
This is an X-ray examination of the inside of the carotid arteries. A catheter (a thin tube) is inserted into the femoral artery in the groin and is guided upwards toward the carotid arteries. A special dye is injected through the catheter into the carotid arteries and an X-ray picture is taken. The locations of defects such as stenosis or blockage are shown on X-ray film.
This technique has a low but important risk of complications, including TIA, stroke, allergic reaction to the dye and kidney toxicity. Your doctor can explain the risks and benefits in greater detail.
TREATMENT OF PAD
Even though the tests may have detected carotid artery disease, surgery may not be recommended, especially in people with mild disease. The doctor may recommend treatment with medicines that lower the risk of stroke, such as aspirin. Some patients with advanced carotid artery disease may have a serious risk of stroke if they do not have treatment. Even in people who have no symptoms yet have severe stenosis, the surgery can be important in reducing the risk of disabling stroke. Treatment options are:
Anti-platelet therapy
Medicines that prevent the formation of blood clots (such as aspirin or clopidogrel) are usually prescribed for at-risk patients, whether or not they have surgical treatment.
Reduction of risk factors
The key risk factors that can worsen plaque formation and vascular disease, and increase the chances of stroke are: smoking, high cholesterol, high blood pressure, obesity, diabetes, heart disease, and a family history of arterial disease. Whether or not their doctor recommends surgery, people should stop smoking, develop healthy eating patterns, lose weight and take medicines to control hypertension, cholesterol, diabetes and other conditions.
Carotid endarterectomy or carotid angioplasty with a stent
For people who have severe stenosis and symptoms, carotid endarterectomy or angioplasty with a stent are treatments most recommended by surgeons and neurologists. The best procedure for you will depend on the shape and condition of your carotid arteries and the risks that apply for you. For people who have severe stenosis but no symptoms, these options are often but not always recommended.
CAROTID ENDARTERECTOMY SURGERY
The surgical removal of plaque from the carotid artery is done in an operating theatre.
After making an incision in the neck, the surgeon exposes the common carotid artery, and the area at which it divides into the internal carotid artery and the external carotid artery.
After clamps are placed around the arteries, the artery is opened by incision.
The surgeon carefully cuts and peels plaque away from the inside wall of the artery.
All of the plaque in the area of the surgery is removed. However, some plaque may still be present in distant parts of the arteries that the surgeon cannot reach.
If a shunt has been used, it is removed, and the incision in the artery is closed using sutures, with placement of a patch.
Carotid endarterectomy usually takes about two to three hours and can be performed with the patient under a general anaesthetic.
Afterwards, the patient is transferred to a ward for monitoring.
CAROTID ANGIOPLASTY AND STENTING
A small puncture is made in the groin and a catheter is introduced into the femoral artery. The catheter is guided to the carotid artery, and an angiogram is obtained to determine the location and severity of the stenosis.
A catheter containing a tiny filter is passed through the stenosis and placed upstream (toward the brain) from the stenosis. The filter traps any blood clots or particles of plaque that may get into the blood while the doctors treats the stenosis. This stops any particles from getting into the brain and causing a stroke.
Once the filter is in place, another catheter with a small balloon at its tip is placed in the stenosis, and the balloon is inflated for a few seconds to open the artery sufficiently to place a self-expanding stent.
As the sheath over the stent is withdrawn, the stent expands, as shown in the illustration. The balloon catheter and filter are removed via the groin puncture site.
The stent stays permanently in place. After several weeks, the artery heals over the stent. The procedure usually takes one to two hours.
An anaesthetist may be present to attend to the patient, who is awake, monitored, sometimes sedated, and kept comfortable. Afterwards, the patient is transferred to a ward for monitoring.
General Risks of any Surgery
Infection: All surgery has a risk of infection. It can be treated with antibiotics and sterile dressings. Rarely, the incision may need to be reopened.
Scarring: Most incisions heal quickly. In some people, healing may be slow, usually because they are elderly. Some people may develop hypertrophic scars or keloids, patches of scar tissue that become inflamed, red and itchy. These can be annoying but are not a threat to health.
Heart attack: During and after the surgery, some patients are at risk of heart attack. This may be due to existing heart disease and the stress of surgery, especially in elderly patients.
Specific risks of carotid endarterectomy
Stroke: If small clots form on the incision in the wall of the artery after surgery, they may be dislodged and swept into the brain by the strong blood flow in the artery, causing a stroke. The risk of a stroke is around 2%. Some strokes can be disabling or life threatening. The risk is lowered by the use of anti-clotting drugs.
Some plaque may be located outside the area of surgery and beyond the reach of the surgeon. That is, it may be high within the internal carotid artery or very low, closer to the chest. During surgery, a small bit of the plaque can dislodge, and be swept into the brain. This can cause a stroke.
Numb patch of skin: A patch of numbness under the chin occurs in most people. It is caused by the cutting of a small nerve during surgery to access the carotid artery. As feeling is the area is then poor, men will have to be careful while shaving.
Nerve damage: Major nerves that lie close to the carotid arteries may be “stressed” or injured by the surgery. Speech and other functions may be disturbed. The nerves will usually return to normal over several days, weeks or months. Permanent major nerve damage is possible but rare.
Bleeding: Bleeding from the carotid artery or wound is rare. Re-operation to stop the bleeding is rarely needed.
Re-stenosis: More plaque can form and cause further stenosis over time which may require surgery. This is uncommon.
Specific risks of carotid angioplasty with stenting
Groin haematoma and bruising, which can take several weeks to resolve.
Damage to the femoral artery at the puncture site and persistent bleeding. The puncture wound in the artery may require surgery to stop heavy bleeding.
Allergy to injected dye.
The risk of stroke is slightly higher than for carotid endarterectomy. Usually a stroke is minor but can be disabling and life threatening.
Recurrent stenosis may occur within the stent and usually can be treated with repeat angioplasty. Open surgery and surgical repair of the carotid artery may be needed but is uncommon.
Heart attack risk is less than for carotid endarterectomy.
If you have any of the following symptoms during your recovery, tell your doctor at once:
- tingling, weakness or numbness of an arm or leg or on one side of the face
- severe headache
- dizziness, unsteadiness, falls
- changes in vision in one or both eyes
- difficulty in concentration and garbled speech
- fever greater than 38 degrees or chills
- redness or drainage from the neck incision which persists.