VSITE Review - Cerebrovascular

  1. Updated Society for Vascular Surgery guidelines for management of extracranial carotid disease
    1. Updated guidelines in development
    1. What is the definition of crescendo TIAs
      1. Frequent repetitive neurologic attacks without complete resolution of the deficit between the episodes, producing the same deficit but no progressive deterioration in neurologic function
      2. If a progressive deterioration then it is a stroke in evolution
    2. Who needs to be screened?
      1. Only 15% of stroke victims have a warning TIA before a stroke so waiting until symptoms occur is not ideal. The purpose of carotid bifurcation imaging is to detect “stroke-prone” carotid bifurcation plaque and identify a high-risk patient likely to benefit from therapy designed to reduce stroke risk
      2. The absence of a neck bruit does not exclude the possibility of a significant carotid bifurcation lesion - focal ipsilateral carotid bruits in symptomatic patients has a sensitivity of 63% and a specificity of 61% for high-grade carotid stenosis (range, 70%-99%).
      3. Screening of the general population is not indicated. Screening should be considered for patients with:
        1. Evidence of clinically significant peripheral vascular disease regardless of age
        2. Patients aged >65 years with a history of one or more of the following atherosclerotic risk factors:
          1. CAD
          2. Smoking
          3. Hypercholesterolemia.
          4. In general, the more risk factors present, the higher the yield of screening should be expected.
    3. US findings that confirm disease
      1. 50-69% stenosis of ICA - Low sensitivity for 50-69% stenosis - a negative ultrasound in symptomatic patients necessitates additional imaging
        1. PSV 125-229 cm/sec
        2. EDV 40-100
        3. Internal/Common Carotid PSV Ratio 2-4
      2. 70-99% stenosis of ICA
        1. PSV >/= 230 cm/sec
        2. EDV >100 (EDV > 140 cm/sec most sensitive for stenosis >80%)
        3. Internal/Common Carotid PSV Ratio > 4
      3. Velocity-based estimation of carotid artery stenosis may need to be adjusted in certain circumstances
        1. Higher velocities in women than in men
        2. Higher velocities in the presence of contralateral carotid artery occlusion.
      4. High carotid bifurcation, severe arterial tortuosity, extensive vascular calcification, and obesity may also reduce the accuracy of DUS imaging
    4. Other Imaging Modalities
      1. CTA
        1. Pro - fast, submillimeter spatial resolution, visualize surrounding structures
        2. Con - cost, contrast exposure
      2. MRA
        1. Pro - no contrast administered; analyze plaque morphology
        2. Con - Does not visualize calcium in plaque; overestimates the degree of stenosis (False positive for 50-69% to be read as >70%)
      3. Catheter-based digital subtraction imaging (DSA)
        1. Still considered by many the gold-standard imaging modality
        2. Reserved for individuals with conflicting less-invasive imaging or those considered for CAS
        3. Con - cost and risk of stroke
    1. Optimal medical therapy
      1. Hypertension
        1. Lowering blood pressure to a target <140/90 mmHg by lifestyle interventions and antihypertensive treatment is recommended in individuals who have hypertension with asymptomatic carotid atherosclerosis or those with TIA or stroke after the hyperacute period.
        2. Each 10-mm Hg reduction in blood pressure amongst hypertensive patients decreases the risk for stroke by 33%.
      2. Diabetes - Glucose control to nearly normoglycemic levels (target hemoglobin A1C <7%) is recommended among diabetic patients to reduce microvascular complications and, with lesser certainty, macrovascular complications other than stroke.
      3. Lipid abnormalities
        1. Risk of stroke decreased by >15% for every 10% reduction in serum LDL in patients with known coronary or other atherosclerosis
        2. Statin agents are recommended targeting LDL of 100 mg/ dL, for those with coronary heart disease or symptomatic atherosclerotic disease, and LDL of 70 mg/dL for very high-risk persons with multiple risk factors
      4. Smoking - Physician counseling is an important and effective intervention that reduces smoking in patients by 10% to 20%
      5. Antithrombotic therapy - There is no evidence to suggest that antiplatelet agents other than aspirin have improved benefit in asymptomatic patients with carotid atherosclerosis
    2. Carotid endarterectomy general principles
      1. TIMING
        1. Recommendations on when to operate after a stroke
          1. Acute stroke with a fixed neurologic deficit of >6h duration:
          2. When the patient is medically stable, less than or equal to 2 weeks after the stroke is preferable to a longer delay
          3. Consider urgent intervention in a medically stable patient with mild-moderate neurologic deficit, if there is a significant area of ischemic penumbra at risk for progression  
          4. Stroke in evolution (fluctuating / evolving neuro deficit) or crescendo TIA (repetitive transient ischemia w improvement between events):
            1. If neuro status is not stabilized by medical intervention consider urgent CEA
          5. CEA is preferred to CAS based on an increased embolic potential of carotid lesions that present in this fashion
        2. What is the only emergent indication for CEA
          1. Crescendo TIAs or a stroke in evolution with a surgically correctable lesion that is identified
        1. General concepts
          1. Patch angioplasty or eversion endarterectomy are recommended rather than primary closure to reduce the early and late complications of CEA (GRADE 1, Level of Evidence A).
        2. Neuromonitoring/Shunting options during a carotid endarterectomy
          1. Local anesthesia with direct neuro monitoring - the patient is awake and moving to command throughout the case. Though improved neuromonitoring has not been shown to reduce MI rate with CEA
          2. Stump pressure
            1. Clamp the inflow and place butterfly attached to a-line tubing into the internal carotid
            2. If stump pressure is > 40 mmHg can proceed, if < 40 place shunt
          3. EEG Neuromonitoring - EEG tech places neuromonitoring, monitored by intraop tech and neurologist remotely, generally clamp ICA for 3 minutes before proceeding, if any deficits unclamp, await normalization of EEG then proceed
          4. Non-selective shunting - shunt all carotids
        3. Techniques to reach internal carotid lesions that are high?
          1. Nasotracheal intubation will help extend the neck to reach higher lesions
          2. Divide posterior belly of digastric to reach high lesions with care to watch for glossopharyngeal
          3. Styloidectomy
          4. Mandible subluxation with assistance from ENT if previous techniques fail.
        4. What is the best technique for a patient with a kinked internal carotid artery?
          1. Eversion carotid endarterectomy will allow you to reduce the redundancy
          2. Otherwise, no advantage has been shown between eversion or patch, both can be shunted
        5. Discuss nerve injuries – where you would encounter these and what deficit would be seen
          1. Hypoglossal
            1. Just above the bifurcation of the carotid artery
            2. Will see tongue deviation to the side of injury
          2. Glossopharyngeal
            1. High dissections under digastric
            2. Difficulty swallowing, aspiration risk, can be devastating
          3. Vagus
            1. Adjacent and lateral to carotid, injury occurs with carotid clamping,
            2. Hoarseness is noted as RLN is a branch off of vagus
          4. Marginal Mandibular (Off of facial nerve)
            1. Retraction at the angle of the jaw for high dissections
            2. Leads to the corner of lip drooping, can be confused with a neuro deficit following the case
        1. What to do if neuro deficits following your carotid endarterectomy
          1. If in OR – perform duplex, if normal open wound and shoot cerebral angiogram
          2. If in PACU or on the floor – many would consider CTA first vs duplex to look for thrombosis
        2. Risk factors and how to manage hyperperfusion syndrome
          1. Defined as an ipsilateral headache, hypertension, seizures, and focal neurological deficits can present 2-3 days out from surgery
          2. Pts with uncontrolled hypertension are at risk for hyperperfusion syndrome, clinical practice guidelines by SVS recommend strict BP control following CEA, maintain a pressure less than 140/80
        1. Recommend f/u US at </=30 days.  >/= 50% stenosis requires further imaging.
        2. Contralateral stenosis
          1. The risk of progression for moderate stenosis at the initial surveillance to severe stenosis can be as high as five times
          2. Requires post-operative surveillance.
    3. Carotid Artery Stenting
      1. In patients aged >70 undergoing CAS the risk of stroke was the highest, presumably due to calcific disease in the arch
        1. Lesion-specific characteristics are thought to increase the risk of cerebral vascular events after CAS and include a “soft” lipid-rich plaque identified on noninvasive imaging, extensive (15 mm or more) disease, a pre-occlusive lesion, and circumferential heavy calcification
        2. This can be reduced, but not eliminated, by using flow-reversal embolic protection rather than distal filter protection
      2. Limited data on CAS in asymptomatic patients - currently is not supported by guidelines or considered reimbursable
      3. Consider CAS in symptomatic patients with >50% stenosis who are poor candidates for CEA due to severe uncorrectable medical comorbidities and/or anatomic considerations (h/o ipsilateral neck dissection or XRT, contralateral vocal cord paralysis, lesions that extend proximally to the clavicle or distal to C2)
      4. Transfemoral Approach vs Transcarotid approach
        1. ROADSTER Trial - single arm study with flow reversal for cerebral protection.  Suggest lower rates of post-op stroke
      5. Post-op follow up - Dual-platelet therapy should be continued for 1 month after the procedure, and aspirin should be continued indefinitely
    4. Management of uncommon disease presentations
      1. Occluded Carotid What to do for occluded carotid?
        1. Leave it alone
      2. What if occluded carotid is still causing TIAs
        1. External carotid endarterectomy and ligation of internal
        2. The addition of oral anticoagulation is likely to reduce the rate of recurrent CVA
      3. What if the patient has severe vertebrobasilar insufficiency and carotid artery disease?
        1. Should undergo carotid revascularization first to improve flow
      4. What about tandem lesions in the carotid in a symptomatic patient, carotid bulb and carotid siphon lesion (high ICA)? How should you treat this?
        1. Treat carotid bulb first, likely the embolic source
      5. Carotid artery dissection
        1. Patients with carotid dissection should be initially treated with antithrombotic therapy (antiplatelet agents or anticoagulation) (GRADE 1, Level of Evidence C).
        2. Patients who remain symptomatic on medical therapy may be considered for intervention. Although data are insufficient to make firm recommendations, the committee unanimously agreed that balloon angioplasty and stenting is currently preferred over open surgery after failed medical management (GRADE 2, Level of Evidence C)
      6. Simultaneous coronary and carotid disease
        1. Patients with symptomatic carotid stenosis will benefit from CEA before or concomitant with CABG. The timing of the intervention depends on the clinical presentation and institutional experience (GRADE 1, Level of Evidence B).
        2. Patients with severe bilateral asymptomatic carotid stenosis, including stenosis and contralateral occlusion, should be considered for CEA before or concomitant with CABG (GRADE 2, Level of Evidence B)
  4. Prospective Trials - MUST READS
    1. Asymptomatic Carotid Atherosclerosis Study (ACAS)
      1. Compared medical management with CEA in asymptomatic patients with > 60% stenosis
      2. 5-year stroke and death rate was 5.1% vs 11%
      3. In women, the benefit of CEA was not as certain as 5y stroke and death rates were 7.3% vs. 8.7%
      4. This was pre statin and Plavix era
    2. North American Symptomatic Carotid Endarterectomy Trial (NASCET)
      1. Compared medical management vs CEA for symptomatic patients with moderate (50-69%) and severe stenosis (>70%)
      2. Only moderate impact for patients with moderate stenosis (50-69%)
      3. Symptomatic patients with >70 % stenosis benefited from CEA, at 18 months 7% major stroke in surgical arm, and a 24% stroke rate in medical arm. 29% reduction in 5-year risk of stroke or death
        1. Patients with severe >70% stenosis had such a dramatic effect the trial was stopped early for this subset and all referred for endarterectomy
      4. No benefit is shown in symptomatic patients with < 50% stenosis
      5. European studies have shown similar results
        1. ACST = ACAS
        2. ECST = NASCET.
    3. Carotid Revascularization Endarterectomy versus Stenting Trial (CREST)
      1. Compared CEA vs. CAS in both symptomatic and asymptomatic patients.
      2. Composite endpoint of 30-day stroke, MI, death equivalent between CEA and CAS
      3. CAS had a significantly higher incidence of stroke and death than CEA and CEA higher incidence of MI
      4. Subanalyses identified that older patients (>70y) had better outcomes after CEA than CAS, the QOL impact of stroke was more significant than that of MI, and anatomic characteristics of carotid lesions (longer, sequential, remote) were predictive of increased stroke and death after CAS
      5. Unfortunately, this study provides a benchmark to strive for, but no other large trials have achieved these results.
      1. Single arm feasibility trial of transcarotid carotid stenting
      2. The results of the ROADSTER trial demonstrate that the use of the ENROUTE Transcarotid NPS is safe and effective at preventing stroke during CAS. The overall stroke rate of 1.4% is the lowest reported to date for any prospective, multicenter clinical trial of CAS.
    5. Trials to look out for in the next few years
      1. CREST-2 - multicenter, randomized controlled trial is underway that is evaluating revascularization against modern intensive medical management
      2. ACT-1 and ACST-2- the role of intervention in asymptomatic patients, designed to compare the early and long-term results of CEA vs CAS and best medical management
      3. ROADSTER-2 - TCAR