Carotid artery disease Flashcards
What diseases affect the carotids?
- Primary
- Atherosclerosis
- Secondary -due to kinking from:
- Arterial elongation
- Fibromuscular dysplasia
- Radiation induced changes
- Extrinsic compression (neoplasm)
- Arteriopathies (temporal arteritis, Takayasus)
Histologic features of atherosclerotic plaques?
- Plaques form in intima and media
- Smooth muscle cells are recruited
- LDL cholesterol, monocytes and platelets are incorporated
- Mature plaque has lipid core and fibrotic cap
How is carotid artery disease classified?
Radiologically by the degreee of stenosis
Clinical sequelae of atherosclerotic disease?
- Thrombosis and embolisation
- Enzymes degrade fibrous cap exposing lipid core
- Core is highly thrombogenic
Most common symptoms of carotid artery disease?
- TIA
- CVA
- Amaurosis fugax
What is a TIA?
Neurologic deficit lasting <24 hours
What is a CVA / stroke?
Neurologic deficit lasting >24 hours
Describe Amaurosis fugax?
- Episode of transient monocular blindness
- (window shade being pulled across the eye)
- Due to acute decrease in blood flow through opthalmic artery to the retina
What are Hollenhorst plaques?
- Cholesterol plaques in the retinal vessels
- Seen at branch points
- Due to arterial to arterial emboli
- Most commonly from a carotid bifurcation plaque
Describe the use of medication on TIA and stroke?
- Antithrombotics (aspirin/clopidogrel/dipyridamole)
- Dual therapy used following TIA
- Statins
- Antihypertensives
- Aim for <140 and <90
Describe a carotid bruit?
- Marker for atherosclerosis
- Indicates risk of cardiac and cerebrovascular events
- Higher degree of stenosis -> higher pitch
Preliminary tests to evaluate a carotid bruit or suspected TIA/CVA?
- Duplex US
- CT angiography
Should a patient with asymptomatic stenosis undergo surgery?
- RCT: Carotid endarectomy (CEA) + aspirin vs. aspirin alone
- Consider surgery if:
- Patient expected to live 3 years
- Low risk of cardiac event
Differentials for carotid artery disease?
- Vasculitis
- Carotid dissection
- Young patients with connective tissue disease/trauma/sudden movement
- Fibromuscular dysplasia
- Young females presenting with focal neuro deficit
Describe the use of carotid artery stenting (CAS) vs CEA?
- Stroke risk higher in perioperative period for CAS
- CEA has a higher risk of MI
- Outcomes for CAS worse in elderly
What cranial nerves can be damaged during CEA and what would this result in?
- Marginal mandibular branch of CN VII:
- Droop of ipsilateral corner of mouth
- CN IX:
- Difficulty swallowing
- RLN of CN X:
- Hoarseness, loss of effective cough
- CN XII:
- Deviation of tongue toward ipsilateral side
Describe when neurological events could occur when performing CEA?
- Dissection => Embolization of material from arterial wall
- Clamping => Ischaemic infarct
- Post-op => Reperfusion
Describe the use of a shunt in CEA?
- Plastic tube which loops around the surgical field
- Provides blood flow during procedure
- Used to avoid intraoperative ischaemia
Describe methods of intraoperative assessment during CEA?
- Neurological status in an awake patient (LA or block)
- Electroencephalogram
- Stump pressure
What is stump pressure?
- Estimates brain blood flow by measuring pressure distal to the clamp
- Mean pressure should be at least 40 mmHg
- Determines need for a shunt during CEA
Describe the risk of resteonsis following surgery?
- Similar long term risk of restenosis in CEA and CAS
- 10yr risk is between 8 and 12%
- First 24 hrs post-surgery: Stenosis due to myointimal hyperplasia
- Beyond this time: Stenosis due to disease progression (atherosclerosis)
Treatment for restenosis after endarterectomy?
- CN injury risk is higher with redo CEA
- Stenting is preferred treatment modality
In which layer of the artery is CEA performed?
Outer layers of the tunica media
When the internal carotid artery is occluded, which branches of the external carotid artery form collaterals and reeestablish circulation in the circle of willis?
- Periorbital branches of the ECA
- Communicates with
- Opthalmic branches of the ICA
Describe both the carotid sinus and carotid body?
- Both located at carotid bifurcation
- Innervated by CN IX and X
Function of the carotid sinus?
- Regulates BP
- Hypertension stimulates efferent impulses to the vasomotor centre in the medulla
- Inhibits sympathetic tone and increases vagal tone
Function of the carotid body?
- Regulates respiratory drive and acid-base status
- Via chemoreceptors
- Induces bradycardia when manipulated (target for carotid massage)
When is surgical intervention strongly indicated in carotid artery disease?
Symptomatic disease with >70% stenosis
Major risk when performing carotid endarectomy?
5% risk of stroke
