1. Copyright ©2013 American Heart Association INTRAVASCULAR ULTRASOUND Sripal Bangalore, M.D., M.H.A. and Deepak L. Bhatt, M.D., M.P.H., F.A.H.A

2. Copyright ©2013 American Heart Association Overview  Intravascular Ultrasound (IVUS)  Rationale for use  Indications  Equipment  Technique  Image Interpretation  Qualitative Analysis  Quantitative Analysis  Artifacts

3. Copyright ©2013 American Heart Association Rationale for use Limitations of angiography:  Under/over estimation of lesion extent and severity  Poor intra/inter observer correlation  Low resolution  Less sensitive to assess plaque characteristics  Two dimensional  Images the lumen and not the vessel wall  QCA measurements prone to magnification errors Advantages of IVUS:  Precise quantification of disease extent and severity  Good intra/inter observer correlation  High resolution  Ability to assess plaque characteristics  360 degree measurement  Images the vessel wall  Accurate sizing of vessel

4. Copyright ©2013 American Heart Association Class IIa  IVUS is reasonable for the assessment of angiographically indeterminate left main CAD. (Level of Evidence: B)  IVUS and coronary angiography are reasonable 4 to 6 weeks and 1 year after cardiac transplantation to exclude donor CAD, detect rapidly progressive cardiac allograft vasculopathy, and provide prognostic information. (Level of Evidence: B)  IVUS is reasonable to determine the mechanism of stent restenosis. (Level of Evidence: C) Indications Levine GN, et al. 2011 ACCF/AHA/SCAI guideline for percutaneous coronary intervention. Circulation. 2011;124:2574-2609.

5. Copyright ©2013 American Heart Association Class IIb  IVUS may be reasonable for the assessment of non–left main coronary arteries with angiographically intermediate coronary stenoses (50% to 70% diameter stenosis). (Level of Evidence: B)  IVUS may be considered for guidance of coronary stent implantation, particularly in cases of left main coronary artery stenting. (Level of Evidence: B)  IVUS may be reasonable to determine the mechanism of stent thrombosis. (Level of Evidence: C) Indications Levine GN, et al. 2011 ACCF/AHA/SCAI guideline for percutaneous coronary intervention. Circulation. 2011;124:2574-2609.

6. Copyright ©2013 American Heart Association Class III NO BENEFIT  IVUS for routine lesion assessment is not recommended when revascularization with PCI or CABG is not being contemplated. (Level of Evidence: C) Indications Levine GN, et al. 2011 ACCF/AHA/SCAI guideline for percutaneous coronary intervention. Circulation. 2011;124:2574-2609.

7. Copyright ©2013 American Heart Association Equipment Mechanical IVUS System:  A single rotating transducer driven by a flexible drive cable  Smaller size compared to solid state systems  More artifacts – Guidewire, NURD, etc.  Higher resolution Solid State System:  Annular array of multiple (64) imaging elements providing imaging by sequentially activating the imaging elements  Larger size compared to mechanical systems  Less artifacts  Ring-down artifact

8. Copyright ©2013 American Heart Association Technique  Anticoagulation: bivalirudin or heparin as per routine clinical practice  6Fr guide catheter to engage the coronary ostium  Standard 0.014 inch guidewire to cross the lesion  Intracoronary nitroglycerin before acquisition of IVUS images to prevent artifacts from catheter induced coronary spasm  A well defined imaging protocol is vital for proper IVUS interpretation and reproducibility  Imaging should be acquired starting at least 10 mm distal to the lesion and preferably at the site of a branch vessel (as a reference marker) with pullback to the proximal vessel

9. Copyright ©2013 American Heart Association Technique  Pullback using motorized transducer pullback (usually at 0.5 mm/s) can be used to survey the artery all the way back to the aorta  Manual transducer pullback can then be used to better interrogate areas of interest  The guiding catheter should be disengaged from the coronary ostium while interrogating an ostial lesion  The motorized pullback technique allows for L-mode (longitudinal) display and estimation of lesion length

10. Copyright ©2013 American Heart Association  Proximal and distal reference segments and the lesion should be identified  Proximal reference: The site with the largest lumen proximal to a stenosis but within the same segment (usually within 10 mm of the stenosis with no major intervening branches)  Distal reference: The site with the largest lumen distal to a stenosis but within the same segment (usually within 10 mm of the stenosis with no intervening branches)  Normal structures: Look for branches, veins and pericardium Image Interpretation - Qualitative

11. Copyright ©2013 American Heart Association Image Interpretation - Qualitative Anterior Interventricular Vein Guidewire IVUS Catheter IVUS of Proximal LAD 1.Innermost layer (intima): Relatively echogenic compared with lumen or media and is comprised of intima, atheroma, and internal elastic lamina 2.Middle layer (media): Less echogenic than the intima 3.Outer layer (adventitia and periadventitial tissue): Relatively echogenic compared with media Trilaminar Image Intima Media Adventitia

12. Copyright ©2013 American Heart Association Image Interpretation-Qualitative IVUS of LAD Acoustic shadowing Calcium Branch vessel

13. Copyright ©2013 American Heart Association Plaque Characterization Soft Plaque - EccentricSoft Plaque - Concentric Soft Plaque  Hypoechoic compared to adventitia  High lipid content

14. Copyright ©2013 American Heart Association Plaque Characterization Fibrous Plaque  Similar/more echogenicity compared with adventitia  Rarely produce acoustic shadowing  Most common type of plaque

15. Copyright ©2013 American Heart Association 180 0 Arc of Calcium360 0 Arc of Calcium Fibrocalcific Plaque  Hyperechoic compared to adventitia  Acoustic shadowing seen  180 0 of calcification must be present before it can be visualized by angiography Plaque Characterization Shadowing

16. Copyright ©2013 American Heart Association Thrombus  Echolucent or variable grey scale appearance  Usually layered, lobulated, or pedunculated  Micro-channels are occasionally present  Diagnosis of thrombus by IVUS is always PRESUMPTIVE Stent Strut Thrombus Subacute stent thrombosis (IVUS after mechanical thrombus aspiration)

17. Copyright ©2013 American Heart Association  Classification of Coronary Dissection  Intimal  Medial  Adventitial  Intramural Hematoma  Intra-stent Dissection n True Lumen (TL): 3-layer appearance (intima, media, adventitia); branches communicating with the lumen n False Lumen (FL): Not all layers are present; branches do not communicate with the lumen Reproduced with permission from Ohlmann, P. et al. Circulation 2006;113:e403-e405 Angiographic and IVUS images of the LAD (1-4): Arrow points at the intimal flap. IVUS catheter is in the true lumen. The false lumen is filled with contrast (black-image 1), blood (gray-image 4) and both contrast and blood (images 2 and 3)

18. Copyright ©2013 American Heart Association Plaque Rupture Fibrous cap Lipid core Reproduced with permission from Tanaka, A. et al. Circulation 2002;105:2148-2152 Plaque rupture at the shoulder

19. Copyright ©2013 American Heart Association Reproduced with permission from Rioufol, G. et al. Circulation 2004;110:2875-2880 A and B show ulcerated plaque. Follow up IVUS 21 months later shows the same ulcerated plaque (non healed). Ulcerated Plaque

20. Copyright ©2013 American Heart Association IVUS of LAD Intramural Hematoma  Accumulation of blood within medial space  Displacement of internal elastic membrane inwards and EEM outwards

21. Copyright ©2013 American Heart Association  True aneurysm: Includes all layers of the vessel wall with an EEM and lumen diameter ≥ 50% larger than the proximal reference segment  Pseudoaneurysm: Does not include all layers of vessel wall and with disruption of the EEM Aneurysms Reproduced with permission from Noguchi, T. et al. Circulation 1999;99:162-163 Coronary angiogram and IVUS imaging of left circumflex artery True Aneurysm Prox Reference

22. Copyright ©2013 American Heart Association Reproduced with permission from Oxford University Press - Ge, J. et al. EHJ 1999; 20: 1707–1716 The white arrows point to a ‘half-moon’ like crest shaped area of the bridge which maintains its shape during systole Myocardial Bridge Diastole Systole

23. Copyright ©2013 American Heart Association Reproduce with permission from Shah, V. M. et al. Circulation 2002;106:1753-1755 Stent Malapposition Stent malapposition (white arrows): 1 or more struts clearly separated from vessel wall with evidence of blood speckles behind the strut

24. Copyright ©2013 American Heart Association Reproduced with permission from Tanabe, K. et al. Circulation 2003;107:559-564 Restenosis: Neointimal Hyperplasia Neointimal hyperplasia in the gap between two stents Neointimal hyperplasia Stent Struts

25. Copyright ©2013 American Heart Association  Quantitative measurements are performed from “leading edge to leading edge” Image Interpretation - Quantitative EEM CSA Lumen CSA Maximal Lumen Diameter Minimal Lumen Diameter Max Plaque Thickness

26. Copyright ©2013 American Heart Association Image Interpretation - Quantitative Definitions  Proximal reference: The site with the largest lumen proximal to a stenosis but within the same segment (usually within 10 mm of the stenosis with no major intervening branches)  Distal reference: The site with the largest lumen distal to a stenosis but within the same segment (usually within 10 mm of the stenosis with no intervening branches)  Largest reference: The largest of either the proximal or distal reference sites  Average reference lumen size: The average value of lumen size at the proximal and distal reference sites

27. Copyright ©2013 American Heart Association Image Interpretation - Quantitative Definitions  Lumen CSA: The area bounded by the luminal border  Minimum lumen diameter: The shortest diameter through the center point of the lumen  Maximum lumen diameter: The longest diameter through the center point of the lumen  Lumen eccentricity: Max lumen dia - Min lumen diameter Max lumen diameter  Lumen area stenosis: Ref lumen CSA - Min lumen CSA Ref lumen CSA  EEM CSA: The area bounded by the external elastic membrane border

28. Copyright ©2013 American Heart Association Image Interpretation - Quantitative Definitions  Atheroma (plaque+media) CSA: EEM CSA - lumen CSA  Max atheroma (plaque+media) thickness: The largest distance from the intimal leading edge to the EEM  Min atheroma (plaque+media) thickness: The shortest distance from intimal leading edge to the EEM  Atheroma eccentricity: (max atheroma thickness – min atheroma thickness)/max atheroma thickness  Atheroma burden: Plaque + media CSA EEM CSA  Remodeling index: Lesion EEM CSA Ref EEM CSA Remodeling index > 1.05  Positive remodeling Remodeling index < 0.95  Negative remodeling Remodeling index 0.95-1.05  No remodeling

29. Copyright ©2013 American Heart Association Reproduced with permission from Dangas, G. et al. Circulation 1999;99:3149-3154 Remodeling Positive Remodeling Negative Remodeling

30. Copyright ©2013 American Heart Association ApplicationIVUS (MLA)CFRFFR Ischemia detection (proximal coronaries except Left Main and SVG) < 2.7 - 4.0 mm 2 < 2.0< 0.75-0.80 Ischemia detection (Left Main) < 6.0 mm 2 < 2.0< 0.75-0.80 Adequacy of stenting> 9.0 mm 2 > 80% Reference Area -≥ 0.90* ≥ 0.94** Image Interpretation - Quantitative * Hanekamp et al. Circulation 1999;99:1015–21 ** Pijls et al. Circulation 2002;105:2950–4

31. Copyright ©2013 American Heart Association Artifacts: NURD Non Uniform Rotational Distortion  Seen with mechanical transducers and results from mechanical binding of the drive cable that rotates the transducer (due to frictional forces)  Due to excessive vessel tortuosity, catheter twisting, calcified arteries, or excessive tightening of the hemostatic valve (O-ring)  Smudging of portions of the image  Fix: Loosening the O-ring

32. Copyright ©2013 American Heart Association Artifacts: Ring-down Ring Down Artifact  Produced by acoustic oscillations in the transducer  Bright halos around the catheter  Creates a zone of uncertainty around the transducer  Less with solid state transducers  Fix: Adjusting the time gain control

33. Copyright ©2013 American Heart Association Artifacts: Blood Speckle Blood Speckle Artifact  Due to increased transducer frequency or decreased velocity of blood (in the region of severe stenosis)  Increased intensity of blood speckle makes delineation of lumen difficult as well as identification of plaques  Fix: Adjusting the time gain control or flushing the catheter with saline or contrast

34. Copyright ©2013 American Heart Association Artifacts: Guidewire Guide Wire Artifact  Seen mainly with mechanical transducers  Acoustic shadow < 12 0 arc