exam 4 new material

Carotid Endarterectomy

Invasive procedure that is performed in the OR. It is the removal of fatty plaque from the neck artery. A tube is inserted above & below the blockage to reroute blood flow.

Recommended if you have a severe narrowing in your CCA.

Angiogram

Imaging technique that uses xray imaging of vessels with an injectable die contrast (radio plaque) to visualize blocks

Vascular surgeon navigates through blockage with a wire with inflatable balloon

Angioplasty

Non invasive. Mechanical dilation of a blocked site in an artery.

After balloon device is positioned across blocked portion of the artery, the vascular surgeon inflates the balloon to expand the artery. The balloon is then deflated & removed.

Which vessels is angioplasty performed?

• femoral artery in the groin

• radial artery in wrist

• reopening of a blocked artery

Which lab is angioplasty performed?

Cath lab with a balloon tipped catheter. Called non invasive because it is catheter based and is minimally invasive.

Carotid stents

Tube made of metal that is inserted into a vessel to keep it open. Stents are used during an angioplasty. Non invasive & performed in femoral or radial artery. Self expanding or balloon deployed.

Extracranial

Arteries that lay outside of the skull or cranium

• vertebral

• ICA

• ECA

• CCA

Intracranial

Arteries that lay inside the skull of cranium

• ICA

• vertebrals

• Circle of Willis

Circle of Willis

Circle of vessels that lie at the base of the brain connecting the anterior & posterior circulatory systems. Provides important collateral pathway in cases of stenosis or occlusion. Developed through enlargement of secondary vessels after obstruction of a main channel.

% of normal circle of Willis

18%-20% of the time

Anterior circulatory system

Consists of the carotid arteries and their branches

Posterior circulatory system

Consists of the vertebral and basilar arteries & their branches

Posterior vessels of the circle of Willis

VA, basilar artery, posterior cerebral artery (PCA), posterior communicating artery (PCoA)

Vertebral Artery

• 1st branch off the SUB A

• Enter the transverse process of the 6th cervical vertebra

• Bend medically before entering cranial cavity through foramen magnum

• R & L VA enter skull through foramen magnum and join to form a singular basilar artery

  • Forms the “Vertebrobasilar” circulation- supplies circle of willis

• Supply the posterior portion of the brain with O2 rich blood

Basilar artery

• forms the union of the two intracranial vertebral arteries

• 3cm long

• BA extends anterior and superior from its origin

• Terminates by diving into the posterior cerebral arteries

Posterior Cerebral Artery (PCA)

• Perfuses the posterior hemisphere (occipital lobe) of the brain

• Divided into 4 segments (P1-P4)

• Only P1 & P2 are seen in transcranial Doppler

• P1- origin to the PCoA

• P2- distal to the PCoA

Posterior Communicating Artery (PCoA)

• Courses posterior & medically from the posterior cerebral artery to join the ICA

• 2nd most common site for intracranial aneurysms

• Most common collateral pathway, connecting the carotid and basilar

Anterior vessels of circle of Willis

ICA, OA, ACA, ACoA

ICA- anterior vessel of Circle of Willis

Supplies anterior portion of brain & eyes

• 4 segments

  • Cervical segment: ICA originates at the bifurcation & ends as the artery enters the base of the skull

  • Petrous segment: begins when ICA enters carotid canal

  • Cavernous segment: portion that forms the “S-shape” is termed the carotid siphone

  • Cerebral/Supraclinoid segment: termination into 4 branches

    • anterior cerebral

    • middle cerebral

    • posterior communicating

    • anterior choroidal

Ophthalmic artery- anterior vessel of Circle of Willis

• 1st branch off of ICA

• Occurs at level of carotid siphon

• Several branches- supraorbital, frontal, nasal

Anterior Cerebral Artery (ACA)

• smaller of the terminal branches of the ICA

• Carries 20%-30% of blood → brain

• A1 connects the R and L sided ACAs

• A2 joins branches of the PCA

Anterior Communication Artery (ACoA)

• Short vessel that connected the anterior cerebral arteries (A1-A2)

• Most common site for intracranial aneurysms

• Most common collateral pathway between R and L hemispheres

Middle Cerebral Artery (MCA)

• Larger terminal branches of the ICA

• Courses laterally towards the temporal bone

• Carries 75%-80% of ICA flow

• Larger than ACoAs

• 4 segments (M1-M4)

• Only vessel that lays on the outside of Circle of Willis

• Initial MCA bifurcation is the 3rd most common site for congenital aneurysms

• The ACoA and PCoA are the 1st and 2nd most common sites for aneurysm formation

Transcranial Doppler (TCD)

Performed with a blind probe; will not see image (only waveform). 1-2MHz pulsed wave transducer

Transcranial Duplex Imaging (TCCD or TCDI)

Usually performed with phased array transducer 2-4MHz

Reasons for doing TCCD/TCDI

• Stroke

• Aneurysm

• Cerebral microemboli

• Stenosis

• Sickle cell disease- disorders of hemoglobin; molecule in RBCs distort into sickle shape

TCD windows

• Transtemporal

• Transorbital

• Suboccipital (transforiminal)

• Submandibular

Transtemporal window

• over the temporal bone

• vessels identified:

  • MCA, ACA, PCA, TICA (terminal ICA), PCoA & ACoA

Transorbital window

Vessels identified:

• ICA siphon, OA

Submandibular window

Vessel identified:

• distal ICA

Sub-Occipital Window

Vessels identified:

• VA, Basilar Artery (BA)

What is window A?

Transtemporal

What is window B?

Transorbital

What is window C?

Suboccipital (transforiminal)

What is window D?

Submandibular

Temporal approach: which vessels, directions, & depths? (MCA)

arterial segment: MCA (M1 & prox M2)

flow direction: towards transducer (M1), away from transducer (M2)

sample volume depth ranges: 30-60

Temporal approach: which vessels, directions, & depths? (ACA- A1)

arterial segment: ACA (A1)

flow direction: away from transducer

sample volume depth ranges: 60-75

Temporal approach: which vessels, directions, & depths? (PCA- P1)

arterial segment: PCA (P1)

flow direction: towards transducer

sample volume depth ranges: 60-75

Temporal approach: which vessels, directions, & depths? (PCA- P2)

arterial segment: PCA (P2)

flow direction: away from transducer

sample volume depth ranges: 60-65

Orbital approach: which vessels, directions, & depths?

arterial segment: OA

flow direction: toward transducer

sample volume depth ranges: 35-55

Foramen Magnum approach: which vessels, directions, & depths? (VA)

arterial segment: VA

flow direction: away from transducer

sample volume depth ranges: 60-90

Foramen Magnum approach: which vessels, directions, & depths? (BA)

arterial segment: BA

flow direction: away from transducer

sample volume depth ranges: 70-120

Anatomy 1-5

1. Brachiocephalic A

2. RCCA

3. R Sub A

4. R ECA

5. R Vert A

Anatomy 6-10

6. R ICA

7. R PCA

8. R PCoA

9. R MCA

10. R ACA

Anatomy 11-15

11. ACoA

12. L ACA

13. L MCA

14. L PCoA

15. L PCA

Anatomy 16-21

16. Basilar A

17. L ICA

18. L ECA

19. L Vert A

20. LCCA

21. L Sub A

What are vessels 1-10?

1. Anterior Communicating Artery

2. Anterior Cerebral Artery

3. Ophthalmic Artery

4. Internal Carotid Artery

5. Anterior Choroidal Artery

6. Posterior Cerebral Artery

7. Basilar Artery

8. Vertebral Artery

9. Posterior Communicating Artery

10. Middle Cerebral Artery