Intravascular Ultrasound

Question 1

What is the lumen area defined as?

Answer 1

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.

Question 2

What does the vessel area represent?

Answer 2

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.

Question 3

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

Answer 3

The atheroma area

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

Question 4

What is the minimum thickness of the atheroma measured from?

Answer 4

Line D on Fig. Q27-1B

Question 5

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

Answer 5

False

The catheter tracing is not used for any clinical measurement.

Question 6

What are the two important features of the true lumen?

Answer 6

• Trilaminar appearance of the wall
• Presence of side branches

Question 7

What is IVUS-derived VH based on?

Answer 7

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

This includes a complex mathematical autoregressive model.

Question 8

What is the predictive value of an FFR ≥ 0.75?

Answer 8

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

Question 9

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

Answer 9

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

Question 10

What was the primary endpoint of the REVERSAL trial?

Answer 10

Percentage change in TAV

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

Question 11

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

Answer 11

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

Question 12

Define positive remodeling.

Answer 12

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

Question 13

What indicates a remodeling index of >1.05?

Answer 13

Positive remodeling

Question 14

What is the significance of a positively remodeled atheroma?

Answer 14

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

Question 15

What is the definition of negative remodeling?

Answer 15

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

Question 16

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

Answer 16

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

Question 17

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

Answer 17

Potential hemodynamically severe stenosis.

Question 18

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

Answer 18

Urgent management is required.

Question 19

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

Answer 19

true lumen of the vessel.

Question 20

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

Answer 20

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.

Question 21

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

Answer 21

Urgent coronary bypass surgery is probably the treatment of choice.

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

Question 22

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

Answer 22

Emergent stenting of the left main is an acceptable alternative.

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

Question 23

What does IVUS imaging provide in comparison to contrast angiography?

Answer 23

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.

Question 24

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

Answer 24

• 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.

Question 25

What characterizes intimal hyperplasia as seen on IVUS imaging?

Answer 25

Intimal hyperplasia appears as echolucent tissue distinct from the speckle of blood elements in the lumen. ## Footnote It indicates prior stent implantation.

Question 26

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

Answer 26

Vein graft lesions are typically echolucent, heterogeneous in density, and represent mixtures of lipid pools, collagen, and thrombotic material. ## Footnote Heavy calcification is rare in these lesions.

Question 27

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

Answer 27

It indicates a hemodynamically significant stenosis likely to cause ischemia on a stress test. ## Footnote This measurement correlates well with an FFR of <0.75.

Question 28

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

Answer 28

Late lumen loss is directly proportional to the degree of neointimal hyperplasia within stented segments. ## Footnote Slot-tube stents reduce the negative remodeling response that contributes to restenosis.

Question 29

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

Answer 29

Adverse events were related to an originally nonculprit lesion in 11.6% of patients. ## Footnote Plaque burden ≥70%, MLA ≤ 4 m², and thin-cap fibroatheroma (TCFA) were predictors of future events.

Question 30

What is the definition of underexpansion in stenting?

Answer 30

Underexpansion occurs when the minimal stent area is <5 m², indicating insufficient expansion during the procedure. ## Footnote This can lead to significant intimal hyperplasia and diameter reduction over time.

Question 31

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

Answer 31

A small postprocedure minimum in-stent lumen area is the most important predictor of TVR. ## Footnote Larger in-stent lumen areas are associated with lower rates of stent thrombosis and restenosis.

Question 32

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

Answer 32

Patients with very late stent thrombosis had longer stents, more overlapping stents, and a higher prevalence of incomplete strut apposition. ## Footnote The in-stent vessel area was significantly larger in the thrombosis group.

Question 33

What are the FFR cutoff values correlated with clinical outcomes?

Answer 33

FFR cutoff values of 0.75 to 0.80 are associated with favorable clinical outcomes and a reduced need for revascularization. ## Footnote Lesions with an FFR > 0.80 generally do not require revascularization.

Question 34

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

Answer 34

Pressure or flow measurements, morphologic delineation using IVUS imaging ## Footnote IVUS stands for Intravascular Ultrasound, a technique for imaging blood vessels.

Question 35

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

Answer 35

0.75 to 0.80 ## Footnote FFR stands for Fractional Flow Reserve, a measurement used to assess the significance of coronary artery lesions.

Question 36

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

Answer 36

Minimum lumen area <3.0 m², area stenosis >60% ## Footnote Sensitivity refers to the ability to correctly identify significant lesions, while specificity refers to correctly identifying non-significant lesions.

Question 37

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

Answer 37

Lumen area <3.0 m² and area stenosis >60% ## Footnote This finding was reported in a study by Takagi A, et al. in Circulation.

Question 38

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

Answer 38

Minimal luminal area ≤4 m², area stenosis >70% ## Footnote This data was reported by Briguori C, et al. in the American Journal of Cardiology.

Question 39

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

Answer 39

IVUS minimum lumen area, area stenosis ## Footnote PCI stands for Percutaneous Coronary Intervention, a non-surgical method used to treat narrowing of the coronary arteries.

Question 40

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

Answer 40

≥4.0 m² ## Footnote A study indicated that with this minimum area, the event rate was acceptably low.

Question 41

What does IVUS imaging help determine in complex CTO PCI?

Answer 41

Whether the wire is in the true or false lumen, extent of dissection ## Footnote CTO stands for Chronic Total Occlusion, a condition where a coronary artery is completely blocked.

Question 42

What advantage does IVUS imaging provide in assessing reference segments?

Answer 42

Typically results in selection of a larger stent diameter than angiography alone ## Footnote This is important for ensuring proper fit and function of stents in coronary arteries.

Question 43

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

Answer 43

Improved clinical outcomes, including reduction in overall mortality, need for revascularization, and stent thrombosis ## Footnote Most evidence is derived from retrospective analyses.

Question 44

What is a significant advantage of OCT over IVUS imaging?

Answer 44

Improved spatial resolution (20 to 40 μm) ## Footnote This allows better definition of thin-cap fibroatheromas (TCFA) and dissection flaps.

Question 45

What limitation does OCT have compared to IVUS imaging?

Answer 45

Does not allow penetration and imaging of the full thickness of the arterial wall ## Footnote OCT provides exquisite resolution but only of the luminal 1 to 2 mm of the wall.

Question 46

What deeper structures can IVUS measure that OCT cannot?

Answer 46

EEM, plaque thickness, and volume ## Footnote EEM stands for External Elastic Membrane, crucial for assessing plaque burden.

Question 47

What are the implications of measuring plaque thickness and volume?

Answer 47

Define future risk of clinical events, study remodeling, disease progression, and response to interventions ## Footnote This was highlighted in the PROSPECT trial.