Carotid disease
Difference between TIA and Stroke
TIA is a global or focal disturbance of brain function lasting less than 24 hours, while stroke has deficits that are not reversed within 24 hours
Causes of stroke
– 25%: Atheroembolism of large vessels (including carotid arteries)
– 25%: Intracranial small vessel diseases
– 20%: Cardiogenic embolism
– 5%: Causes not defined
– 25%: Unknown causes
Arterial Embolization
Thrombus and debris originating from atherosclerotic plaques migrate and obstruct intracranial vessels, triggering symptoms.
Symptoms
Symptoms depend on the location of the obstruction and the affected brain function. The most common obstructions occur in the middle and anterior cerebral arteries.
Anatomy and Symptoms
– Anterior Cerebral: Irrigates the medial surface of the frontal lobe, anterior portion of the basal ganglia, and internal capsule. Ischemia causes lower limb weakness, sensory loss, and apathy.
– Middle Cerebral: Irrigates the lateral surface of the brain, causing hemiplegia, hemianopsia, aphasia, and dyspraxia.
Embolization to the retinal artery, a branch of the ophthalmic artery. Remember that the carotid injury is on the same side as the symptoms. Its symptoms are amaurosis fugax.
Symptoms such as dizziness, pre-syncope, seizures, and peripheral neurological symptoms are not attributed to carotid arteries.
Diagnosis and Screening
– Ultrasonography: Method of choice for screening, with high sensitivity and specificity.
– Risk Criteria: All patients over 65 with two or more risk factors must be screened.
The intimal medium complex, which gives an average of 1.6, we know that above 1.5 is plaque.
Angiography
Angiography is the gold standard for diagnosis
The NASCET (North American Symptomatic Carotid Endarterectomy Trial) and ECST (European Carotid Surgery Trial) methods are two approaches to measuring carotid stenosis.
NASCET method
The NASCET method calculates stenosis by comparing the diameter of the narrowest point of the carotid artery with the diameter of the normal artery distal to the stenosis. The formula is as follows:
1. Measure the diameter at the point of most significant stenosis: The measurement is made at the narrowest part of the carotid artery.
2. Measure the diameter of the distal normal artery: The measurement is made in the part of the artery that is beyond the stenosis and appears normal.
3. Apply the formula: The percentage of stenosis is calculated using the above formula.
ECST method
The ECST method calculates stenosis by comparing the diameter of the narrowest point of the carotid artery with the estimated diameter of the original carotid artery before any disease. The formula is as follows:
Measure the diameter at the point of greatest stenosis: This is the narrowest part of the carotid artery.
1. Estimate the diameter of the original normal artery: The measurement is an estimate of the diameter of the carotid artery before any disease.
2. Apply the formula: The percentage of stenosis is calculated using the above formula.
Comparison between NASCET and ECST
• NASCET: Tends to provide lower stenosis percentages because it compares to a regular portion of the artery distal to the stenosis.
• ECST: Tends to give higher stenosis percentages because it compares to an estimate of the original diameter of the artery before any disease.
Practical example
Let us assume an example where the diameter at the point of most significant stenosis is 2 mm, the normal distal diameter is 6 mm (for NASCET), and the original diameter estimate is 8 mm (for ECST).
The NASCET method calculated a stenosis of 67%, while the ECST method calculated 75%.
Clinical Treatment
All patients with carotid atherosclerosis, whether symptomatic or asymptomatic, should receive optimized medical treatment.
Best Medical Therapy (BMT)
– Blood pressure control (<140/90)
– Diabetes control (HbA1c <7)
– Quit smoking
– Physical activity
– Reduction of alcohol
– Control of dyslipidemia (LDL <70)
– Use of antiplatelet agents (AAS 100 mg/day)
– Use of high-potency statin (atorvastatin 40 mg/day)
Indication for Surgical Treatment
Asymptomatic and Symptomatic Patients with Carotid Stenosis
A patient is considered asymptomatic when they have an extracranial carotid stenosis greater than 50% without evidence of clinical or radiological atheroembolism within the last six months. This means that the patient may not have symptoms. However, if an MRI shows an ischemic area corresponding to carotid stenosis, that patient is considered symptomatic even without clinical symptoms.
Therefore, the absence of clinical symptoms does not exclude the symptomatic condition. It is essential to stratify patients using complementary exams. Symptomatic patients are those with extracranial carotid stenosis greater than 50% and with an episode of clinical or radiological atheroembolism in the last six months.
Asymptomatic Patients Who May Benefit from Surgical Intervention
There are clinical and imaging findings that can predict which asymptomatic patients are at greater risk of developing a stroke. These findings include:
-Microembolization on transcranial Doppler
-Hypoechogenic plaque
-Progression in the degree of stenosis observed in serial examinations
-Silent infarction on computed tomography (CT) associated with stenosis, also detectable on magnetic resonance imaging (MRI)
-Reduced cerebrovascular reserve
-Luminal fair hypoechoic area size
-Intraplate hemorrhage, detectable by resonance or ultrasound
-Contralateral stroke with this is associated with reduced cerebrovascular reserve
If an asymptomatic patient requires treatment, endarterectomy is the preferred option unless the patient is at high surgical risk.
Asymptomatic Patients
The current trend is to avoid surgery for asymptomatic patients, except in high-risk cases.
Symptomatic Patients
Symptomatic patients are divided into three groups based on the severity of the stenosis:
-Stenosis less than 50%
-Stenosis between 50-69%
-Stenoses greater than 70%
The intervention is indicated for stenoses greater than 50%, with a preference for endarterectomy. Patients with carotid subocclusion and occlusion do not indicate revascularization.
Anesthesia Decisions
The surgical team must choose the type of anesthesia. General anesthesia is more comfortable and makes the team’s work easier as the patient sleeps. Local anesthesia allows immediate neurological assessment of the patient.
Carotid Bulb Block
Blocking the carotid bulb is not recommended, as there is no evidence that it reduces hemodynamic events, hypertension, or arrhythmia. Some professionals use 1% lidocaine without vasoconstrictor to anesthetize the carotid bulb.
Shunt
The decision to use a shunt should be based on the case’s particularities and the surgical team’s experience. Some mandatory indications include contralateral occlusion or contralateral critical stenosis. The reflux pressure must be measured; if it is less than 45 mmHg, a shunt is recommended to ensure adequate supply through the circle of Willis.
Endarterectomy Techniques
The team must decide whether to use traditional or eversion techniques, as there is no evidence of benefit or harm between them.
Patch Usage
Routine patch use is recommended over primary closure, but there is no conclusive evidence about the best material.
Clamping Procedure
In endarterectomy, the internal carotid artery is the first clamped and the last unclamped. Some services unclamp the internal carotid artery gradually to prevent clot formation.
Cervical Drain
A large-caliber cervical drain is mandatory and can be removed on the same day or after 24 hours.
Heparin Reversal
Reversal of unfractionated heparin with protamine should be considered to prevent neck hematoma and the need for re-exploration.
Angioplasty
Angioplasty should be considered an alternative to endarterectomy when the risk of stroke or death is less than 6%. This is a second option for patients with:
-Unfavorable anatomy
-Hostile neck
-Very low or very severe ejection fraction
Angioplasty Procedures
Study of the Aortic Arch
Access: Preferably through the common femoral artery, but can be through the brachial artery.
The use of brain protection devices is recommended.
Complications
Main cause of death: Acute Myocardial Infarction (AMI)
Neurological Events: Second cause of death.
Cervical Hematoma: Early re-approach necessary.
Neuronal Injury: Injuries to the hypoglossal nerve, vagus nerve, mandibular branch of the facial nerve, superior laryngeal nerve, and accessory nerve.
Versão 13.06.2024
