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Invasive Cardiology Board Review > Intravascular Ultrasound > Flashcards

Intravascular Ultrasound Flashcards

1
Q

What is the lumen area defined as?

A

The area bound by the leading edge of the intima or the interface between the echo-dense intima and the echolucent blood elements in the lumen

Line B on Fig. Q27-1B illustrates this definition.

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2
Q

What does the vessel area represent?

A

The area bound by the EEM, identified as the interface between the leading edge of the echo-dense adventitia and the echo-lucent medial layer

Line C on Fig. Q27-1B illustrates this definition.

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3
Q

What does the difference between the lumen and EEM areas represent?

A

The atheroma area

This includes both the atheroma and the thickness of the media.

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4
Q

What is the minimum thickness of the atheroma measured from?

A

Line D on Fig. Q27-1B

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5
Q

True or False: The catheter artifact is used for clinical measurement.

A

False

The catheter tracing is not used for any clinical measurement.

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6
Q

What are the two important features of the true lumen?

A
  • Trilaminar appearance of the wall
  • Presence of side branches
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7
Q

What is IVUS-derived VH based on?

A

Advanced analysis of the radiofrequency backscatter of the ultrasound signal using a larger number of parameters

This includes a complex mathematical autoregressive model.

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8
Q

What is the predictive value of an FFR ≥ 0.75?

A

Predicts a low risk of death or cardiac events in the ensuing 2 to 3 years on medical therapy alone.

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9
Q

What does an IVUS left main lumen area ≥5.9 m² correlate with?

A

An FFR ≥ 0.75, both measures strongly predict event-free survival over a 3-year period.

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10
Q

What was the primary endpoint of the REVERSAL trial?

A

Percentage change in TAV

TAV was calculated as the sum of differences between EEM and lumen areas.

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11
Q

What is the remodeling response in lesions treated with balloon angioplasty or atherectomy?

A
  • Adaptive remodeling: Increase in vessel area between 24 hours and 1 month
  • Constrictive remodeling: Decrease in vessel area between 1 and 6 months
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12
Q

Define positive remodeling.

A

Expansion of the EEM of the arterial wall at sites of atherosclerosis to accommodate atheroma volume and preserve lumen size.

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13
Q

What indicates a remodeling index of >1.05?

A

Positive remodeling

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14
Q

What is the significance of a positively remodeled atheroma?

A

Usually larger in size and more likely to present with unstable coronary syndromes.

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15
Q

What is the definition of negative remodeling?

A

Local shrinkage of the vessel size at the site of disease.

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16
Q

What was the main finding in the ASTEROID trial regarding very intensive lipid-lowering therapy?

A

Significant reduction in PAV after 24 months of therapy, indicating regression of disease.

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17
Q

What does significant plaque burden with minimal calcification indicate in IVUS imaging?

A

Potential hemodynamically severe stenosis.

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18
Q

What should be done if there is a left main trunk dissection?

A

Urgent management is required.

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19
Q

Fill in the blank: The IVUS catheter artifact is seen in the _______.

A

true lumen of the vessel.

20
Q

What is the role of IVUS in imaging false channels during cases of dissection or plaque rupture?

A

IVUS provides better visualization of false channels when saline or contrast is injected, enhancing echo density differences.

This allows real-time observation of fluid movement from the true to the false lumen.

21
Q

What is the recommended management for left main coronary dissection if the patient is hemodynamically stable?

A

Urgent coronary bypass surgery is probably the treatment of choice.

If stabilization with IABP is possible, this may be pursued.

22
Q

What is the acceptable alternative management for a patient with left main coronary dissection considered too unstable?

A

Emergent stenting of the left main is an acceptable alternative.

Immediate notification of the cardiac surgeon is essential in both scenarios.

23
Q

What does IVUS imaging provide in comparison to contrast angiography?

A

IVUS imaging offers a detailed tomographic perspective of both the lumen and the wall of the artery.

It clarifies and complements the understanding of luminal silhouettes from angiography.

24
Q

List some clinical situations where IVUS imaging is beneficial according to ACC/AHA guidelines.

A
  • Assessment of stent deployment adequacy
  • Evaluation of suboptimal angiographic results
  • Determination of restenosis mechanisms
  • Evaluation of difficult-to-image coronary anatomy
  • Preinterventional assessment of coronary calcium extent

IVUS is the gold standard for identifying cardiac allograft vasculopathy.

25
Q

What characterizes intimal hyperplasia as seen on IVUS imaging?

A

Intimal hyperplasia appears as echolucent tissue distinct from the speckle of blood elements in the lumen.

It indicates prior stent implantation.

26
Q

What are the typical characteristics of vein graft lesions seen on IVUS?

A

Vein graft lesions are typically echolucent, heterogeneous in density, and represent mixtures of lipid pools, collagen, and thrombotic material.

Heavy calcification is rare in these lesions.

27
Q

What is the significance of a minimum lumen diameter of <2 mm as seen on IVUS?

A

It indicates a hemodynamically significant stenosis likely to cause ischemia on a stress test.

This measurement correlates well with an FFR of <0.75.

28
Q

What is the relationship between neointimal hyperplasia and late lumen loss in stented segments?

A

Late lumen loss is directly proportional to the degree of neointimal hyperplasia within stented segments.

Slot-tube stents reduce the negative remodeling response that contributes to restenosis.

29
Q

What were the findings of the PROSPECT trial regarding adverse events related to nonculprit lesions?

A

Adverse events were related to an originally nonculprit lesion in 11.6% of patients.

Plaque burden ≥70%, MLA ≤ 4 m², and thin-cap fibroatheroma (TCFA) were predictors of future events.

30
Q

What is the definition of underexpansion in stenting?

A

Underexpansion occurs when the minimal stent area is <5 m², indicating insufficient expansion during the procedure.

This can lead to significant intimal hyperplasia and diameter reduction over time.

31
Q

What is a key predictor of target vessel revascularization (TVR) following stenting?

A

A small postprocedure minimum in-stent lumen area is the most important predictor of TVR.

Larger in-stent lumen areas are associated with lower rates of stent thrombosis and restenosis.

32
Q

What did IVUS findings reveal about very late stent thrombosis in DES patients?

A

Patients with very late stent thrombosis had longer stents, more overlapping stents, and a higher prevalence of incomplete strut apposition.

The in-stent vessel area was significantly larger in the thrombosis group.

33
Q

What are the FFR cutoff values correlated with clinical outcomes?

A

FFR cutoff values of 0.75 to 0.80 are associated with favorable clinical outcomes and a reduced need for revascularization.

Lesions with an FFR > 0.80 generally do not require revascularization.

34
Q

What functional assessments can be used when encountering an intermediate lesion?

A

Pressure or flow measurements, morphologic delineation using IVUS imaging

IVUS stands for Intravascular Ultrasound, a technique for imaging blood vessels.

35
Q

What are the FFR cutoff values associated with favorable clinical outcomes?

A

0.75 to 0.80

FFR stands for Fractional Flow Reserve, a measurement used to assess the significance of coronary artery lesions.

36
Q

What IVUS measurements maximize sensitivity and specificity for identifying hemodynamically significant lesions?

A

Minimum lumen area <3.0 m², area stenosis >60%

Sensitivity refers to the ability to correctly identify significant lesions, while specificity refers to correctly identifying non-significant lesions.

37
Q

What combination of IVUS criteria had 100% sensitivity and specificity in identifying significant lesions?

A

Lumen area <3.0 m² and area stenosis >60%

This finding was reported in a study by Takagi A, et al. in Circulation.

38
Q

In another study, what minimal luminal area and area stenosis were the best indicators of hemodynamic significance?

A

Minimal luminal area ≤4 m², area stenosis >70%

This data was reported by Briguori C, et al. in the American Journal of Cardiology.

39
Q

What were the independent predictors of events after deferring PCI in a retrospective analysis?

A

IVUS minimum lumen area, area stenosis

PCI stands for Percutaneous Coronary Intervention, a non-surgical method used to treat narrowing of the coronary arteries.

40
Q

What minimum lumen area allows for reasonably safe deferral of PCI?

A

≥4.0 m²

A study indicated that with this minimum area, the event rate was acceptably low.

41
Q

What does IVUS imaging help determine in complex CTO PCI?

A

Whether the wire is in the true or false lumen, extent of dissection

CTO stands for Chronic Total Occlusion, a condition where a coronary artery is completely blocked.

42
Q

What advantage does IVUS imaging provide in assessing reference segments?

A

Typically results in selection of a larger stent diameter than angiography alone

This is important for ensuring proper fit and function of stents in coronary arteries.

43
Q

What association has been suggested between IVUS use and clinical outcomes in stenting of the left main trunk?

A

Improved clinical outcomes, including reduction in overall mortality, need for revascularization, and stent thrombosis

Most evidence is derived from retrospective analyses.

44
Q

What is a significant advantage of OCT over IVUS imaging?

A

Improved spatial resolution (20 to 40 μm)

This allows better definition of thin-cap fibroatheromas (TCFA) and dissection flaps.

45
Q

What limitation does OCT have compared to IVUS imaging?

A

Does not allow penetration and imaging of the full thickness of the arterial wall

OCT provides exquisite resolution but only of the luminal 1 to 2 mm of the wall.

46
Q

What deeper structures can IVUS measure that OCT cannot?

A

EEM, plaque thickness, and volume

EEM stands for External Elastic Membrane, crucial for assessing plaque burden.

47
Q

What are the implications of measuring plaque thickness and volume?

A

Define future risk of clinical events, study remodeling, disease progression, and response to interventions

This was highlighted in the PROSPECT trial.

Invasive Cardiology Board Review (42 decks)

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