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Year 3 Cardiac physiology > CC10: IVUS and OCT > Flashcards

CC10: IVUS and OCT Flashcards

1
Q

Uses of intravascular imaging

A

-Understand mechanism and pathophysiology of coronary syndromes
-Morphology of atherosclerotic plaques
-Optimise stent deployment
-Understand factors responsible in less optimal outcomes (e.g. stent thrombosis, sub deployment, restenosis)

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2
Q

Why is OCT not good for ostial left main disease?

A

-To inject contrast the catheter needs to be engaged
-Catheter will be in region of interest

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3
Q

How are IVUS images produced?

A

-Passing electrical current through a miniature transducer incorporated in tip of specialised catheter
-Transducer contains piezoelectric crystals
-Ultrasound reflected at interfaces between tissues or structures of different density
-Signal returns to transducer to create an electrical impulse

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4
Q

What does colour shading mean on IVUS?

A

-White signal = more reflection
-Black signal = less signal reflected

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5
Q

What are the 2 catheter types for IVUS?

A

Rotational IVUS
-single piezoelectric crystal with 1800rpm
-40-60MHz
-Min 5Fr
-Radiopaque markers to help guide lesion length

Phase array
-Multiple stationary placed piezoelectric transducers
-20MHz
-Plug and play - no catheter prep required
-Min 5Fr
-Radiopaque markers to help guide lesion length

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6
Q

Steps in performing IVUS

A

-Enter patient information on IVUS system
-Guide catheter and guide wire advanced
-Anticoagulation administered at therapeutic dose
-Nitrate given to optimise vessel size
-IVUS catheter advances distal to area of interest
-Go live and recording/pullback started
-Either manually or mechanically pulled back to proximal vessel

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7
Q

What are the views in IVUS?

A

Cross-sectional tomographic view
-Cross section 2D image of vessel lumen

Longitudinal view
-Useful review of plaque burden in vessel
-Useful for lengths (if using pullback sled)

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8
Q

Common lesions in IVUS?

A

-Calcium blocks US signals
-Appears very bright

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9
Q

Concentric vs Eccentric lesion

A

Concentric - lesion all the way round
Eccentric - lesion on one side

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10
Q

Types of artefact in IVUS

A

Ring Down artefact - common with phase array systems
-produced by acoustic oscillations in transducer
-gives bright artefact around catheter

Air artefact - common with rotational catheters
-Air in system, not flushed adequately

Non-uniform rotational distortion - hindered rotation
-can be present in bending or tortuous vessels

Reverberation
-strong reflectors (e.g. calcium, stents, guidewires/catheters may be reflected back and forth to transducer
-Displayed as layers

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11
Q

Indications for IVUS?

A

-Is lesion significant?
-Distal vessel diameter - what size stent?
-Proximal vessel diameter - how much to post dilate?
-Is there ostial disease?
-Associated with large branches?

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12
Q

What does post PCI IVUS check?

A

-Good sizing between stented region and non-stented
-Not stenting into area of disease
-Stent well deployed

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13
Q

What is shown here?

A

-Guidewire artefact

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14
Q

How do you treat malapposed stent?

A

-Post dilation balloon

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15
Q

Air and calcium on IVUS

A

-Air is dark
-Calcium is bright

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16
Q

Things to look out for in IVUS

A

ST elevation
-If lesion is significant, catheter may obstruct flow
-Flushing catheter when intra-coronary may give air embolus

Blunting of arterial pressure
-If using a 5Fr system
-If using a 6Fr system with multiple wires

17
Q

What is OCT?

A

-General principle of operation similar to IVUS
-OCT uses infrared rather than ultrasound
-Infrared light has greater image resolution, but less tissue penetration
-High resolution images
-But more limited on depth (not appropriate for large vessels)

18
Q

Features of OCT catheter

A

Rotational catheter
-Always need to connect to pullback device
-Needs to be pulled back at fast speed due to blood clearance
-Infrared light does not travel through blood so contrast is used

19
Q

Why is IVUS used over OCT?

A

-OCT uses contrast
-Contraindicated in renal disease

20
Q

In what situations is OCT less effective?

A

May produce poor quality images in ostial lesions LMS/RCA
-poor contrast flushing
-less effective in large vessels

Highly tortuous vessels, high calcium burden, severe stenosis
-Hard to advance catheter
-May interfere with blood clearance

21
Q

Steps in OCT

A

1) Enter patient information on OCT machine
2) Cover pullback doc with sterile bag
3) Remove OCT catheter from sheath
4) Purge catheter with 100% contrast using purge syringe
5) Connect catheter to pullback doc
6) Recommend to check live view functioning prior to insertion

22
Q

Guide wire/guide catheter in OCT?

A

Guide catheter
-Preferable 6F for contrast injection
-Needs good coaxial alignment to facilitate effective and safe contrast injection

-Guide wire positioned distally
-Ensure full anticoagulation

23
Q

What are the lengths of acquisition in OCT?

A

-54 or 75mm pullback length
54mm - high definition, slower pullback (3.0 secs)
75mm - faster pullback speed (2.1 secs)

24
Q

What are the types of pullback in OCT?

A

Manual or automatic

-Manual needs operator and controller both ready to ensure good pullback
-Automatic will pullback when contrast is detected

25
Q

What are the 4 Ps in OCT?

A

Position - catheter distal to lesion
Purge - catheter lumen
Puff - inject some contrast to evaluate clearance
Pullback - initiate

26
Q

What indicates sub-optimal clearance in OCT?

A

-Blood swirls

27
Q

What is MLA?

A

-Minimal Lumen Area

28
Q

Types of plaque in OCT

A
29
Q

Therapy for each plaque type in OCT

A

Lipid - Direct stenting
Fibrotic - Compliant balloon
Mild/moderate calcium - NC balloon
Severe calcium - Atherectomy or shockwave

30
Q

What are artefacts in OCT?

A

Non-uniform rotational distortion -rotation of pullback restricted

Saturation - high intensity signal can’t be accurately detected by detector

Discontinuity - in the lumen caused by artery motion or imaging wire movement causing misalignment of lumen

31
Q

Dissection on OCT

A
32
Q

SCAD on OCT

A

Spontaneous Coronary Artery Dissection

33
Q

Is IVUS or OCT better for dissections?

A

OCT

34
Q

IVUS vs OCT

A
35
Q

Pre stent workflow?

A

-Length of lesion?
-Plaque type and does it need modification?
-Vessel size and size of stent?

36
Q

Post stent workflow?

A

-Any edge dissections?
-Malapposition of stent?
-Optimal stent expansion?

37
Q

Are IVUS/OCT physiological assessments?

A

NO
-Pressure wire is

38
Q

Red thrombus and white thrombus vs lipid and calcium

A

Year 3 Cardiac physiology (30 decks)

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