Carotid Duplex Doppler (M4U1)

What are the primary goals of extracranial duplex doppler? (HINT: 2)

- Identify pts at risk for stroke m/c due to development of atherosclerotic plaque

- Facilitate tx decisions for pts such as conservative, surgical, or interventional methods

What are the seondary goals of extracranial duplex doppler? (HINT: 3)

- Document disease progression

- Document re-stenosis among pts treated w/ endartectomy/interventional procedures

- Detect non-athero conditions (dissections, FMD, artertitis, aneurysm, rad effects, carotid body tumour)

80% of strokes are ischemic. What percent of this is from the carotids?

20%

What is an ischemic stroke?

Embolic/thrombotic occurences that interrupt blood flow to the brain, m/c in smaller intracranial arteries

What is a hemorrhagic stroke?

Small intracranial vessel rupture which deprives brain tissue of blood flow

(makes up 20% of strokes)

What is a TIA?

Transient Ischemic Attack (Mini-stroke)

- Temporary loss of blood supply to the brain (less than 24 hours)

- No permanent damage

- Emergency condition that could lead to CVA (more probable CVA if lasts over an hour)

What is a RIND?

Reversible Ischemic Neurological Defict

- Symptoms lasting b/w 24-72 hours

- Emergency condition b/c it could lead to CVA

- NO permanent damage

What is a CVA?

Cerebrovascular Accident (stroke)

- Significant ischemic event leading to infarct causing long lasting (fixed/permanent) neurological damage and impairment

- Varying degrees of recovery

TRUE or FALSE: The m/c cause of TIA/CVA is downstream hypoperfusion due to high grade stenosis.

FALSE: The m/c cause of TIA/CVA thrombotic and emboli going to smaller terminal branches in the brain or eye

What is a cardiac emboli?

Thrombus forms in the left atrium and gets pumped out into the systemic circulation, ending up smaller terminal branches in the brain

- related to atrial fibrillation

What could atrial fibrillation be a sign of?

Cardiac emboli

What is involved in an extra-cranial cerebrovascular physical exam? (HINT: 3)

- Auscultation for bruits using stethoscope (can be graded 1, 2, 3 depending on degree of stenosis)

- Pulse palpation over carotids, axiala, brachial, and radial arteries

- Bilateral brachial pressures

Name a clinical indication for an extracranial duplex exam.

- Asymptomatic neck bruits

- Hemispheric cerebral/ocular TIA

- Hx of CVA

- Screening prior to major cardiac, peripheral vascular, or other surgery

- Surgical/interventional procedure follow up

- Vertebral-basilar artery related symptoms

TRUE or FALSE: All neck bruits come from the neck.

FALSE: Bruits can be heard at the carotid bulb but can be 'referred' from the heart. Additionally, only 1/3 of bruits are related to hemodynamically significant stenosis of the ICA

What 2 branches of the ICA feed the anterior brain?

- ACA = anterior cerebral artery

- MCA = middle cerebral artery

TRUE or FALSE: A patient presents with right sided numbness (paresthesia). This means that there is potential stenosis in the right ICA causing these symptoms.

FALSE: There is potential stenosis in the LEFT ICA. The left side of the brain controls the right side (and vice versa. Therefore, if a patient presents with right-sided symptoms, there is an issue with the left brain hemisphere, which is supplied by the left ICA.

(Additionally, the chances of the cause being a carotid vessel is low - only 20%)

What are the carotid territory symptoms that could indicate potential stroke? (HINT: 3)

Acute presentation of:

- Unilateral weakness, numbness (paresthesia), or paralysis

- Aphasia

- Dysphasia (partial loss of speech)

What is aphasia?

expressive disorder and speech center deficit that impairs a person's ability to formulate and comprehend language

(carotid territory symptom)

What is dysarthria?

Problems w/ muscles that help produce speech, leading to slurred/garbled speech

(diff to dysphasia, which is a condition from neurological issues with Broca and Wernicke's area)

What is the symptom of an ocular TIA? (HINT: 1)

Amaurosis fugax = loss of vision in one eye due to embolism to opthalamic artery (ischemia of eye)

(occurs in IPSILATERAL ICA/CCA)

TRUE or FALSE: A patient presents with loss of vision in their left eye only. This could be as a result from an embolism from the left ICA.

TRUE: Ipsilateral CCA/ICA is the affected vessel in ocular TIA symptoms/amaurosis fugax.

Name 2 symptoms of non-localizing/non-focal TIA/CVA?

Symptoms DON'T provide clue as to which side of brain/eye affected:

- Unconsciousness

- Amnesia

- Behavioural changes (confusion)

- Severe headaches

- Vertebral-basilar type symptoms

- Diplopia (double vision in one or both eyes)

What are the symptoms of vertebrobasilar insufficiency?

Interruption of blood flow at vertebral or basilar arteries may lead to:

- Dizziness/disorientation

- Vertigo (sensation of spinning)

- Diplopia (double vision in one or both eyes)

- Ataxia (loss of control of voluntary muscle movements, leading to balance issues)

What parts of the brain does vertebrobasilar insufficiency affect?

Posterior circulation - cerebellum, brainstem, midbrain, visual cortex)

(that's why symptoms have to do with balance, vision, etc.)

TRUE or FALSE: Patients must fast before a carotid U/S exam.

FALSE: No specific preparation is needed for this exam. Patients may just need to remove jewelery or anything obstructing access to the neck

What is the patient position for a carotid U/S exam?

Supine, chin titled up and head turned away from the side being imaged

What is the protocol for a carotid U/S exam?

- CCAs

- Carotid bulb (if possible)

- ICAs

- ECAs

- Vertebral arteries

- Subclavian arteries

Why does the vertebral artery appear fractured after C6 during an ultrasound exam?

The vertebra artery enters at C6 of the cervical spine and continues to travel intracranially

Why is the proximal CCA and SCA not well seen?

The sternum and clavicle in front of these vessels obstructs their view

In a carotid exam, there is laminar flow everywhere except...

- Carotid bulb (flow reversal turbulence)

- Rt subclavian origin (due to branching)

Describe the waveform of the CCA.

- Low to moderate resistance

- Sharper peak w/ pan-diastolic flow

Describe the waveform of the ICA and vertebrals.

- Low resistance

- Broad peaks

- Pan-diastolic flow

Describe the waveform of the ECA.

- Moderate resistance

- Sharp peaks

- Temporal tap sometimes (If you tap on superficial temporal artery by ear, may get tapping reverberations in proximal ECA waveform)

Describe the waveform of the subclavian artery.

- Multiphasic

- High-resistance

- Disturbed flow pattern close to branch origin at aortic arch or at brachiocephalic a.

Flow separation is normal in the carotid bulb. Why may there be NO flow separation seen? (HINT: 3)

- Bulb is anatomically small and has little room for blood to be disturbed

- Angle/slice through 3D vessel doesn't include flow separation (may be seen when sweeping the bulb)

- There is plaque development in bulb area

How can you differentiate b/w the ECA and ICA?

- ECA is smaller and more medial

- ECA has multiple branches

- ECA succeptible to temporal tap (not always reliable)

- ECA is moderate resistance (ICA is low resistance)

Why is imaging the carotid bulb and ICA incredibly important? (HINT: 3)

- Hot spot for patho changes (m/c athero)

- Diagnosis at this location drives tx decisions

- ICA feeds the brain