Cardio

Question 1

How does carotid USS differ from carotid CTA or MRA (or catheter angiography) in determining degree of carotid artery stenosis?

Answer 1

Carotid USS estimates the degree of stenosis based on elevations in blood flow velocity observed in the target vessel as opposed to the other modalities which undertake anatomic measurements of luminal narrowing (e.g. measure residual lumen diameter at the most stenotic portion of the vessel and compare this with the lumen diameter in the normal internal carotid artery distal to the stenosis)

Velocity criteria that correlate with angiography measurements have been developed that are categorical (rather than linear) ie 50-69% stenosis

Question 2

What is the gold standard for diagnosing internal carotid artery stenosis?

Answer 2

Catheter cerebral аոgiοgrарhу BUT it is invasive, time consuming, assoc with stroke risk

Question 3

What is the preferred diagnostic strategy in symptomatic (eg stroke/TIA) carotid artery disease?

Answer 3

Usually CT or MR head and neck angiogram (given usually performed in ED at time of stroke presentation)

Question 3

What is the preferred diagnostic strategy for asymptomatic carotid artery disease?

Answer 3

Carotid duplex USS

Question 3

If a carotid stenosis less than 50% is identified on initial imaging, what further evaluation needs to be done?

Answer 3

Usually none - effectively excludes haemodynamically significant CAD

Only exceptions:
- carotid stenosis that is unusually distal and beyond the field of insonation for CDUS

• short-segment stenosis in regions of heavily calcified plaque on СΤA in which adequate assessment of the residual lumen may be difficult

Question 4

What further evaluation is indicated if a symptomatic carotid artery stenosis 50-99% is detected?

Answer 4

Confirmation with an alternative modality is generally advisable, as two separate noninvasive diagnostic modalities concordant for high-grade stenosis increase accuracy;
If concordant - proceed to revasc
If discordant - consider catheter angiogram

However some experts are happy with just one positive test

Question 5

What further evaluation is indicated if an asymptomatic carotid artery stenosis 50-99% is detected?

Answer 5

Depends on if they are candidate for revascularisation

If not - serial carotid duplex USS

If they are - obtain alternative test + treat with statin and antiplatelet and aggressive risk factor modification

Question 6

If a patient is found to have complete carotid artery occlusion on CTA can you trust it?

Answer 6

No, whilst CDUS and МRA are very accurate ; have to be suspicious of CTA because with increasing speed of image acquisition, can have “pseudo-occlusion” whereby image acquisition occurs before contrast bolus can fully opacify the affected vessel

Therefore if complete occlusion found on CTA suggest alternative study eg CDUS or MRA to confirm

Question 7

What are the advantages of CT (head and neck) angiogram for the detection of carotid artery disease?

Answer 7

Quick (an important advantage in patients who are uncooperative or claustrophobic)
Can be useful in situations of difficult anatomy e.g. severe kinking

Question 8

What are the disadvantages of CT (head and neck angiogram) for the detection of carotid artery disease?

Answer 8

Significant contrast bolus (same or higher dose than catheter angiogram) which poses risks to kidneys
+
Radiation risk
+
Pseudo-occlusion risk

Question 9

What are the advantages and disadvantages of carotid duplex USS for evaluation of carotid artery disease?

Answer 9

Adv:
- noninvasive, safe, and inexpensive
- no claustrophobia
- no contrast
- can be easily repeated
- highly accurate

Disadv:
- operator dependent
- tends to overestimate the degree of stenosis
- less precise at identifying minimal stenoses (ie gets more accurate the higher the degree of stenosis)
- may be limited by features such as calcific carotid lesions, tortuous or kinked carotid arteries, and patient body habitus
- only a portion of the cervical internal carotid artery extending just past the carotid bifurcation can be evaluated (Fortunately, the vast majority of atherosclerotic stenoses occur within this region)

Question 10

Is CDUS a good modality for detecting carotid artery dissection and why?

Answer 10

No - CDUS can only evaluate a portion of the cervical internal carotid artery extending just past the carotid bifurcation

However, carotid dissections often occur in the more distal portion of the cervical carotid artery and thus will not be accurately identified by СDUS

Question 11

After carotid artery intervention (ie endarterectomy or stenting) what is the best imaging modality to evaluate for restenosis?

Answer 11

CDUS is commonly used to conduct serial monitoring of the carotids over time to ensure patency of the vessel and evaluate for restenosis because it is:
low cost,
easy to use
accurately monitors changes

But structural changes to the carotid wall after endarterectomy or stenting may alter compliance of the vessel wall which in turn may impact the relationship between flow velocity and degree of stenosis such that standard velocity criteria may be inaccurate - note modified criteria have been developed to address this

Note the accuracy of CTA and especially MRA may be negatively impacted by stent artifact

Question 12

What is the definition of symptomatic extracranial carotid atherosclerotic disease?

Answer 12

Neurologic symptoms (incl TIA, transient monocular blindness, stroke) that are sudden in onset and referable to the appropriate internal carotid artery distribution (ipsilateral to significant carotid atherosclerotic pathology)

Question 13

Αthеrοѕϲlerоѕis of the internal carotid artery at the bifurcation accounts for what percentage of ischaemic strokes?

Answer 13

10-12%

Question 14

What is the mechanism by which carotid artery disease may cause an ischaemic stroke?

Answer 14

Progressive atheromatous plaque at the carotid bifurcation results in luminal narrowing, often accompanied by ulceration

This may then lead to embolization, thrombosis, or reduced brain perfusion (more likely in the setting of bilateral disease)

Question 15

What is the treatment of symptomatic carotid artery disease?

Answer 15

Intensive medical management +/- carotid artery revascularisation

Question 16

What does intensive medical management of carotid artery disease entail?

Answer 16

1) Antithrombotic therapy
2) High-potency stаtiո therapy
+
3) Risk factor modification, including blood pressure control, glucose control, weight control, and lifestyle modification with smoking cessation, exercise, and recommended dietary modifications

Question 17

Which patients are most likely to benefit from carotid artery revascularisation?

Answer 17

Patients with recently symptomatic carotid stenosis of 70 to 99 percent who have a life expectancy of at least two years (ideally within 2 weeks of symptoms)

Patients with recently symptomatic carotid stenosis of 50 to 69 percent who have a life expectancy of at least three years, particularly if can be done within 2 weeks of symptoms (beyond 2 weeks - benefit is less certain overall, and females, in particular, may not benefit from revascularization beyond two weeks from symptom onset)

Question 18

What is the preferred modality of carotid artery revascularisation?

Answer 18

Carotid endarterectomy rather than transfemoral carotid artery stenting when there is a surgically accessible carotid artery lesion; no clinically significant cardiac, pulmonary, or other disease that would greatly increase the risk of anaesthesia and surgery; and no prior ipsilateral endarterectomy

Question 19

Which patients are unlikely to benefit from carotid artery revascularisation?

Answer 19

• Stenosis less than 50 percent.
• Severe comorbidity due to other surgical or medical illness.
• Strоkе associated with persistent, severe neurologic deficits and disability that precludes preservation of useful function.
• Near occlusion of the symptomatic ipsilateral internal carotid artery
• Total occlusion of carotid artery

Question 20

What are the benefits of carotid artery revascularisation?

Answer 20

To prevent one event at five years for ipsilateral carotid territory ischemic ѕtrоke and operative strοke or death, the number needed to treat (NNT) was 6

Note whilst CEA and CAS have similar long-term benefits, CAS has higher rates of periprocedural complications and 30d death (note was transfemoral ?if transradial approach mitigates these risks somewhat)

Question 21

In what circumstances may you consider carotid artery stenting over endarterectomy?

Answer 21

• A carotid lesion that is not suitable for surgical access
• Radiation-induced stenosis
• Carotid restenosis after endarterectomy
• Clinically significant cardiac, pulmonary, or other disease that greatly increases the risk of anaesthesia and surgery
• Unfavorable neck anatomy including contralateral vocal cord paralysis, open tracheostomy, or prior radical surgery

Question 22

Which factors influence the benefit and risk of Carotid endarterectomy?

Answer 22

Baseline stroke risk - the higher the greater the benefit from CEA

Location of event: Hemispheric ischaemia rather than retinal ischaemia

Age: Older age (>70yo)

Gender: Males > females

Presence of contralateral carotid artery disease - if present, favour surgical revasc over medical mx (despite increased periprocedural risk)

Combined perioperative morbidity and mortality that exceeds 6 percent

Timing of revasc - best between 2 days and 2 weeks after event (ie stroke)

Question 23

What is the definition of asymptomatic carotid atherosclerotic diease?

Answer 23

The presence of atherosclerotic narrowing of the extracranial internal carotid artery (significant = >50% stenosis) in individuals WITHOUT a history of ipsilateral carotid territory ischemic strokе or transient ischemic attack in the last six months

Question 24

What is the annual stroke risk in patients with asymptomatic carotid artery disease?

Answer 24

0.5 to 1.0 percent annually
+
Also a marker for MI and vascular death

Question 25

Does an isolated unilateral carotid stenosis cause vertigo, diplopia, lightheadedness or syncope?

Answer 25

No

Question 26

What is the preferred treatment approach for asymptomatic extracranial carotid artery disease?

Answer 26

Intensive medical management

Revascularisation is controversial given periprocedural risks and low absolute risk reduction assoc with revasc ie 2.9% risk of periprocedural stroke or death vs 1% absolute risk reduction; NNT = 33

Controversial but some evidence of equivalence between intensive medical tx and CEA in asymptomatic px ie risk of stroke similar

Others would argue still benefit for CEA in asymptomatic 70-99%

SPACE-2 trial suggested nil significant differences in 30d death, cumulative stroke or ipsilateral stroke out to 5 years between intensive medical mx, CEA + medical mx, CAS + medical mx but limitations incl stopped early due to slow recruitment and low event rates