Intravascular ultrasonography (IVUS) provides essential information for treating complex aortic dissections. IVUS can identify intimal entry tears, assess true lumen size for endograft sizing, confirm stent apposition, and determine if the primary endpoint of endograft coverage is achieved. It also aids in understanding branch vessel involvement and the mechanism of malperfusion. IVUS is particularly useful when malperfusion is present, as it can help differentiate static from dynamic obstruction and guide intervention. In complex cases, IVUS provides critical imaging of vessel wall anatomy not visible on other modalities like CT, helping operators successfully treat dissections and reestablish organ perfusion.

1. Utility of Intravascular Ultrasonography (IVUS)
in Complex Aortic Dissections
Roy M. Fujitani, MD, RVT, DFSVS, FACS
Professor of Surgery
Vice-Chair, Surgical Education and Faculty Development
Department of Surgery
Division of Vascular & Endovascular Surgery
University of California - Irvine

2. No Disclosures

3. Acute Aortic Syndrome (AAS)1
Global Grand Rounds | © 2017 Medtronic, plc. All Rights Reserved
2 Clough, RE & Nienaber, CA. Nat Rev Cardiol. 2015;12(2):103-
14
% of AAS2 62 – 88% (~1/3 Type B) 10 – 30% 2 – 8%
1 Mussa FF, et al. JAMA. 2016;316(7):754-763

4. Dissection happens usually within the media layer of the aortic wall
PATHOGENESIS: WHERE IN THE VESSEL WALL?

5. DEFINITIONS OF COMPLICATED TYPE B DISSECTION
• Refractory hypertension/pain
– Hypertension resistant to > 3 agents not present before the onset of the
dissection
• Viscerals: Mesenteric and celiac
– Increase in LFTS, amylase, bilirubin, nausea or vomiting with appropriate
BP control
• Renal: Imaging findings
– Absence of nephrogenic effect on the delayed phase of the CT
• Imminent Rupture
– Increase in the amount of peri-aortic hematoma and/or hemorrhagic
pleural effusion in 2 successive CT scans

6. PRESENTATION
~ 30% Type B dissection are complicated
>2/3: malperfusion
• 56% lower extremity
• 36% Renal
• 20% visceral
• 3% spinal cord
• 8% Other malperfusion
1/3: rupture
• Different priority
• Algorithm directed at stopping bleeding
• Then you look for malperfusion
Multiple strategies:
“Stepwise Approach”
Pape LA, etal, J Am Coll Cardiol 2015 Jul 28; 66(4): 350-8

7. Society Guidelines for Aortic Dissection and IMH – Type B
Global Grand Rounds | © 2017 Medtronic, plc. All Rights Reserved
1 Hiratzka LF, et al. JACC. 2010;55(14):e27-e129
2 Erbel R, et al. Eur Heart J. 2014;35(41):2873-2926
Stanford Type ACCF/AHA/AATS/ACR/ASA/SCA/SC
AI/SIR/STS/SVM 2010 1 Level (Grade) ESC 2014 2 Level (Grade)
Aortic Dissection, Type B
Complicated Surgical procedure I (B) TEVAR I (C)
Uncomplicated Medical therapy I (B) Medical therapy or TEVAR I (C) or IIA (B)
Intramural Hematoma, Type B
Complicated Surgical procedure IIA (C) TEVAR IIA (C)
Uncomplicated Medical therapy I (B) Medical therapy I (C)

8. DIAGNOSTIC STRATEGIES
Tools
1. CT
2. MRI
3. TEE
4. IVUS
Goals of Imaging Studies
1. Confirmation of the diagnosis
2. Localization of the entry tear
3. Extent of aortic dissection
4. Classification of aortic dissection
5. Indication of hemorrhage
6. Branch vessel involvement

9. AIMS OF ENDOVASCULAR TREATMENT FOR ACUTE AORTIC
DISSECTION
1. Cover the entry tear
2. Treat or prevent rupture
3. Reestablish organ / limb perfusion
4. Restore flow in true lumen
5. Induce aortic remodeling
• Shrink false lumen, expand
true lumen

10. INTIMAL ENTRY TEAR:
Location: Descending aorta
Size: > 10 mm

11. SIZING RULES FOR TYPE B DISSECTION
• Measure diameter of healthy aorta
immediately proximal to the dissection
• May need to “correct” the size depending
the location of measurement
• Use CTA and IVUS for more accurate sizing
• 10% or less oversizing

12. ESSENTIAL IMAGING ADJUNCTS FOR TREATMENT
– Imaging
• TEE
• IVUS
• MRA
Essential
Adjuncts
for
Treatment

13. IMAGING OPTIONS: IVUS
• ↓ contrast media (pts with ↑ creatinine)
• Most accurate for vessel sizing
• ↓ fluoroscopy exposure to the patient
• Shows plaque morphology, calcium &
thrombus
• Identify ideal landing areas
Images
courtesy
of
Ali
Khoynezhad,
MD
Essential
Adjuncts
for
Treatment

14. IVUS – CORE ENDOVASCULAR TECHNOLOGY
• Transmural vessel wall anatomy
• Identification of side branch and intraluminal wall
lesion characterization
• CRITICAL APPLICATIONS
– Define dissection anatomy and flow lumen
– Size thoracic aorta during endograft deployment for
transections
– Identify device deployment site
Essential
Adjuncts
for
Treatment

15. X-SECTIONAL IMAGE: 3-LAYER NORMAL MUSCULAR ARTERY
Ultrasound
Probe
Wire artifact
Vessel Wall
Vessel Wall
Images
courtesy
of
Rodney
White,
MD
Essential
Adjuncts
for
Treatment

16. INTRAVASCULAR ULTRASOUND (IVUS)
• Navigate true lumen
• Confirm vessel diameters
• Size endograft
• Identify entry tear(s)
• Assess stent apposition
PRE
POST
False
lumen
Images
courtesy
of
Rodney
White,
MD
Essential
Adjuncts
for
Treatment
• Determine primary endpoint of
endograft coverage
• Confirm no retrograde type A
• Assess endograft expansion/lumen
gain

17. CTA COMPARED TO IVUS
Images courtesy of Rodney White, MD
Essential
Adjuncts
for
Treatment

18. DISSECTION CTA COMPARED TO IVUS
Celiac SMA IMA
Images
courtesy
of
Rodney
White,
MD
Essential
Adjuncts
for
Treatment

19. Device in true lumen
Images
courtesy
of
Rodney
White,
MD
Essential
Adjuncts
for
Treatment
PROCEDURAL
ANGIO AND IVUS
IN THE AORTIC
ARCH

20. AORTIC DISSECTION
Images
courtesy
of
Rodney
White,
MD
Essential
Adjuncts
for
Treatment

21. AORTIC DISSECTION
Probe in true
lumen
False Lumen
Fenestration of
the flap at the
branch vessel
Images
courtesy
of
Rodney
White,
MD
Essential
Adjuncts
for
Treatment

22. Carotid Subclavian
Chronic
Dissection
Renal
Perfusion
Images
courtesy
of
Rodney
White,
MD
AORTIC DISSECTION
Essential
Adjuncts
for
Treatment

23. MALPERFUSION
• Lower extremity < renal < mesenteric ischemia
• Differential diagnosis
– anatomic (static)
– dynamic obstruction
– both
• Procedural tools
– Angiographic
– IVUS
– Manometry
Williams DM, et al., Op Tech in Thor and Cardiovasc Surg. pp. 2-11. 2009

24. Complication directed
procedures decrease
mortality.
MALPERFUSION
Operative mortality
increased from 9% to
38% with
malperfusion

25. UNDERSTANDING MALPERFUSION:
MECHANISM OF BRANCH COMPROMISE
Dynamic obstruction Static obstruction
Cleavage plane of dissection
extends into ostium
Prolapsed septum into ostium
during cardiac cycle
Trimarchi S et al, Ann Cardiothorac Surg 2014;3(4):418-422

26. MALPERFUSION: SITUATIONAL ANALYSIS
Have the dynamics of the true lumen changed on IVUS?

27. PATIENT INFORMATION
JR
• 57 yr old male with 18 hr history of severe chest
& back pain
• Absent femoral pulses & abdominal pain with
WBC 30,000
• CTA confirmed acute Type B Dissection with
occlusion distal thoracic aorta
Essential
Adjuncts
for
Treatment

28. Essential
Adjuncts
for
Treatment

29. Preliminary Diagnostic IVUS

30. Essential
Adjuncts
for
Treatment
Images courtesy of Rodney White, MD

31. Celiac Artery
Renal Arteries
SMA
Images courtesy of Rodney White, MD
Essential
Adjuncts
for
Treatment

37. Post TEVAR Completion IVUS

38. Images
courtesy
of
Rodney
White,
MD
POST TEVAR
Essential
Adjuncts
for
Treatment

39. Celiac Artery
Renal Arteries
SMA
Images courtesy of Rodney White, MD
Essential
Adjuncts
for
Treatment

43. Summary
• IVUS provides imaging of transmural vessel wall anatomy and
critical applications toward defining dissection anatomy and
definition of flow lumen.
• IVUS provides for verification of aortic diameters at attachment
zones, location of branch vessels, and dynamic assessment of
septal behavior (branch patency; static vs dynamic septal
movements)
• Intravascular ultrasonography (IVUS) provides an integral
adjunct for the treatment of complex thoracoabdominal aortic
dissections particularly when malperfusion is clinically
encountered.

44. “
Division of Vascular and Endovascular Surgery
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