|Critical carotid artery stenosis|
|Carotid artery stent in place|
|Restored brain blood flow after
stroke using multiple techniques
|Carotid plaque removed during
Stroke affects over 600,000 Americans annually and is the third leading cause of death and the leading cause of disability in the United States. For strokes that occur within regions of the brain fed by the carotid arteries, 17% of patients die within 30 days of their stroke while 40% die within 5 years. Of the long term survivors, the impact is significant as 15% require institutional care, 1/3 require assistance with activities of daily living, and 2/3 have decreased socialization. The economic effects stroke, including both the cost of additional care and lost productivity, are estimated at $30 billion annually in the US alone.
There are primarily 2 types of stroke: ischemic (lack of blood supply) and hemorrhagic (bleeding in the brain). Hemorrhagic strokes account for about 15% of all stroke events and are due to chronic hypertension (burst blood vessel), trauma, ruptured cerebral aneurysm, arteriovenous malformations, and bleeding disorders. Ischemic strokes account for 85% of strokes and are related to progressive narrowing or occlusions of the arteries that feed the brain, most commonly, the carotid arteries. A transient ischemic attack (TIA), otherwise known as a mini stroke, is an event in which the stroke symptoms last less than 24 hours. By definition, the symptoms of a TIA will be temporary. Characteristically, TIA symptoms tend to last only for several minutes then completely resolve. If any of the neurologic symptoms or deficits persists beyond 24 hours, this constitutes a stroke. TIAs may precede an actual stroke as much as 30% of the time. TIA’s should be considered a warning sign of an impending stroke and demand immediate attention.
In patients presenting with neurologic deficits, one must also consider that those symptoms could be related to other conditions such as seizure, brain tumors, abscess, migraine headaches, or subdural hematoma. CT scans or MRI scans of the brain are helpful in identifying many of these causes and can often times identify the stroke itself. In some cases, early small strokes may not be identified on the imaging studies. Ultrasound examinations of the carotid arteries are also helpful in identifying the degree of narrowing present within these vessels and the likelihood of carotid artery disease causing or contributing to the neurologic event.
Most strokes affect the brain territory fed by the carotid artery while a small percentage are related to the vertebrobasilar system feeding the back of the brain. Classic symptoms of TIA and stroke (carotid territory) include weakness, numbness, or tingling of the face, arm, and leg (alone or in combination) affecting one side of the body; or blindness in one eye described as a black curtain coming down through the field of vision. When strokes or TIA’s are related to carotid artery disease, visual changes are usually on the same side as the diseased carotid artery while the face, arm, and leg symptoms on the side opposite the affected carotid. Left brain events can also affect the patient’s speech. Strokes or TIA’s affecting the vertebrobasilar circulation can cause symptoms of ataxia (staggering gait), double vision, vertigo, and weakness or paralysis that can affect all the extremities.
There are several risk factors commonly associated with stroke. Hypertension (systolic and diastolic) increases one’s risk for stroke. Reducing systolic hypertension (systolic BP >170 mmHg) by 11mmHg has been shown to reduce the risk of stroke by 35% while reducing diastolic hypertension by 6mmHg is associated with a 40% stroke risk reduction (Collins et al, Lancet 335:827-38, 1990). Diabetes has been shown to increase the risk of stroke by 2.5-3.5 times over non-diabetics as well as increasing the risk of carotid atherosclerosis. Smoking and hyperlipidemia are associated with a 2 times increase in stroke risk, primarily related to their affect on atherosclerosis. Aspirin is an effective antiplatelet agent for stroke prevention in patients with peripheral vascular disease, angina, and symptomatic atherosclerotic vascular disease.
In patients with symptoms of TIA or stroke who have more than 50% narrowing of their carotid artery, or in patients with more than 70% narrowing and no symptoms, the preferred treatment is to eliminate the carotid artery obstruction by either a carotid endarterectomy (surgical removal) or a stent. The purpose of treatment is to prevent additional symptoms of TIA or stroke. Strokes can occur with either types of treatment in up to 4% of patients. At EvergreenHealth Heart & Vascular Care, we are regionally recognized leaders in the treatment of carotid artery disease. Our stroke rates are over 4 times less than the national average. We also are the only practitioners on the eastside qualified to place carotid stents and are part of the SAPHIRRE carotid artery stent registry sponsored by Cordis.