1. PROPOSITION OF KNOWN BUT NEW FOR TAVI IMAGING MODALITY
Prof. Armine Zarayelyan
Endovascular Surgery and Diagnostic Center

2. THE THEORETICAL PLANE OF THE PROJECT Developed by Professor Armine Zarayelyan

3. Background I
Aortic stenosis (AS) is the most common valvular disorder and its prevalence is going to increase dramatically with the aging of the population
Surgical aortic valve replacement is the definitive therapy for patients with severe AS who have symptoms or left ventricular dysfunction
TAVI has been developed as an alternative to surgical aortic valve replacement with promising results for patients with severe AS considered to be at high or prohibitive surgical risk
Being less invasive than open-chest aortic valve replacement, good outcome and effectiveness of TAVI procedure, it remains associated with the potential for serious complications and still confined to the treatment of elderly and high-risk patients
Today there is evidence for the link between annulus size measured by methods currently available and such complications as a paravalvular AR (PVAR) and AV conduction disturbance (AVCD).

4. Background II
Accurate aortic annulus size evaluation is difficult and might require different technique.
The knowledge of measuring limitations of the aortic annulus by echocardiography, angiography, or computed tomography and development of new more accurate imaging modalities may decrease the possibility of patient-prosthesis mismatch.
There is no any clinical study of dynamic aortic root anatomy with detailed description of the clinical anatomy and dynamic of aortic root, valves and nearby anatomic structures of the heart, which participates in aortic valve movement because of absence such an imaging technology.

5. AIM
The aim of this proposal is theoretically substantiate the possibilities and advantages of use of IVUS imaging modality in evaluation of structures and measurements of aortic root for TAVI and apply for practical application and check of this theoretical proposition

6. TASKS I (Theoretical plane)
To analyze the advantages and limitations of existing today imaging modalities for TAVI.
To provide the comparison analyses of the technical specifications of IVUS imaging modality and other imaging modalities using today for TAVI.
To theoretically develop the schematics and image models of aortic root that can be obtained by IVUS imaging modality.
To investigate the applicability and develop the technique for IVUS imaging modality use in measurement of aortic root structure’s dimensions and diameters and evaluate its changes during cardiac cycle in patients with and without AS.

7. TASKS II (Practical plane)
To develop the guidance and standard for aortic root structure by IVUS visualization in healthy population and in patients with AS.
To compare the obtained by IVUS imaging modality results with results obtained by other imaging modalities.
To evaluate the value of obtained by IVUS results for TAVI prostheses size proper selection and consequently for TAVI complication rate changes .
To use the anatomic and dynamic specifications of aortic root obtained by IVUS for TAVI prostheses further development and elimination of complication rate.

8. It is important to be familiar not only with the anatomic relationship between aortic root structures but also with its changes during cardiac cycle
It is equally important to be familiar with the complex anatomic relationships between the aortic root and its surrounding cardiac structures and their dynamic during cardiac cycle.

9. SO, WHY THEY ARE CHANGES AND CHANGES IN SO DIFFERENT WAYS???
Different Shapes of TAVI after deployment:
Circular (A), triangular (B), and elliptic (C, D).
SO, WHY THEY ARE CHANGES AND CHANGES IN SO DIFFERENT WAYS???
Influence of Size or Shape of the Orifice on the TAVI
No leaflet distortion is present (A).
Distortion occurred after TAVI deployment in an elliptic (B), a triangular (C), or an undersized circular orifice (D).

10. FOR SUCCESSFUL TAVI IT IS NECESSARY
Accurate measurement of the true sagittal and coronal diameters of the aortic annulus at all level
Knowledge of degree of sagittal and coronal diameters changes during cardiac cycle.
Accurate measurement of aortic root structure’s dimensions and distances such as from basal ring to coronary artery orifice, dimensions of aortic valve leaflets, interleaflet triangles, sinus Valsalva, thickness of aortic wall on different level of aortic root , etc during cardiac cycle.
Determination of degree of participation of such aortic structures as interleaflet triangles, sinus Valsava, aortic wall, aortic valve leaflets, LVOT wall in the aortic annulus diameter changes during cardiac cycle.

11. Coronal / Sagital = 5 - 20 % Sagital & coronal Sagital

12. SPECIFICATIONS, ADVANTAGES & LIMITATIONS OF IMAGING MODALITY I
Adv & Limitation
Specifications
Imaging modality
2D TTE
2D TEE
Angioscopy
3D TEE
CT / MRI
ICE
IVUS
Adv
Dimension 3D
Lim 2D
Measurement diameters
Sagittal & Coronal
Only sagittal
Cut plane
0° PA - coronal
90°LAO - sagittal
At any plane or level (orthogonal or oblique to them planes
At any plane or level (orthogonal or oblique to them planes)
From aortic root near-field cardiac structures – SVC, RA
Perpendicular to aortic root axis – cross-sectional & longitudinal section from inside of aorta
Tangential across the aortic root
Not perpendicular to aortic annulus
Not perpendicular to aortic annulus.
Additive effect of accumulative errors
Perpendicular to body axis, not perpendicular to aortic annulus. Standard orthogonal axial & sagittal views need to be reconstructed for obliquely oriented aortic valve.
Resolution
In-plane <1,0mm
In-plane – ,5 mm
Through plane –
50-150μm
3-5mm
Through plane ,25-1,5mm

13. SPECIFICATIONS, ADVANTAGES & LIMITATIONS OF IMAGING MODALITY II
2D TTE
2D TEE
Angioscopy
3D TEE
CT / MRI
ICE
(UltraICE/AcuNav)
IVUS
Advantages
Easy and widely use, repeatability + -
+/-
- (+)
Have confirmed protocol and guide
-/+
Standardization of aortic root structures visualization
Limitations
Limitation caused by aortic valve calcification
Limitation caused by aortic motion
Radiation exposure
Need in general anesthesia
Need in contrast medium
Under-/over- estimation of aortic annulus
High self-cost

14. How IVUS Works
To obtain 360° cross-sectional image,the ultrasound beam must be scaned through a full circle, and the beam direction and deflection on the display must be synchronized. This can be achieved
- by mechanically rotating the imaging elements, or
- by using electronically switched phased array.

15. Digital, 64 element (Plag&Play)
Company
Boston Scientific 
Volcano Corporation 
Catheter model
Atlantis PV Peripheral 
Sonicath Ultra 9 Peripheral  
Visions PV .018  
Visions PV ” 
Visions PV 8.2 French  
Imaging method
Rotational 
Digital, 64 element  (Plag&Play)
Grayscale IVUS
Yes 
Yes+(ChromaFlow)
Bloodflow imaging
No 
Frequency, MHz
15 MHz 
9 MHz 
20 MHz 
10 MHz 
Maximum imaging diameter
30 mm 
50 mm 
24 mm 
60 mm 
Tip entry profile
.105 
.118 
.030 
.055 
.058 
Tip to transducer
1.5 cm 
1 cm 
10-13 mm 
12 mm 
Diameter at transducer (French) 8  9 
3.5 
8.2 
Maximum outer shaft (French)
8.5 
3.4  7 
Radiopaque markers
One 
25, 1 cm apart 
Wire lumen length
101 cm 
NA 
31 cm 
90 cm 
Working length (cm)
95 
110 
135 
90 
Maximum guide wire
.035 
.018 
.038 
Minimum guide catheter size (Fr)
6 (ID ≥.064) 
Minimum sheath size (French) 6 
Delivery platform
Monorail 
Rapid exchange 
Over the wire 
Catheter list price
$725 
$980 
Available on request 

16. VISIONS® PV 8.2F INTRAVASCULAR ULTRASOUND IMAGING CATHETER
The Visions PV 8.2F catheters may be used only with the In-Vision Imaging System, Volcano s5 or Volcano s5i imaging system, which offers plug and play digital IVUS simplicity for immediate imaging

17. Following removal of the aortic leaflets, three crescentic ridges mark the hinge lines. The broken line indicates the level of the ventriculo-arterial junction. Two of the three interleaflet fibrous triangles (o) are shown. The irregular shape marks the site of the atrioventricular conduction bundle and left bundle branch.
AV conduction bundle
R/N ILT
L/N ILT
VAJ BR
10-12mm below BR
3-5mm below BR
STJ
SVml

18. INTENDED IVUS Visions® PV 8.2F USE
The IVUS Visions® PV 8.2F catheters are designed for use in the evaluation of vascular morphology in blood vessels of the peripheral vasculature by providing a cross-sectional image of such vessels.
The Visions PV 8.2F ultrasound imaging catheters are designed for use as an adjunct to conventional angiographic procedures to provide an image of the vessel lumen and wall structures and dimensional measurements from the image.

19. At the level of VAJ Rivus = 30mm NCS LCS RCS Diastolic Systolic
RA, RV, Conduction system, Septal leaflet of TV
N/R ILT
RCS
LCS
NCS
LA, RA, TS
LA, free pericardium
RA, free pericardial space
L/N ILT
LA, AL MV
R/L ILT
Space between Ao & PT
Diastolic Systolic
Dsag(d)=21,7mm Dsag(s)=18,23mm
Dcor(d)=27,5mm Dcor(s)=23,1mm
Rivus = 30mm
D IVUS PV 8.2 =60mm
D IVUS Atlantis PV= 30mm
Posterior
Anterior L R
Nadir
At the level of VAJ
Projection of commissures at STJ

20. LVOT 10-12 mm below BR Diastole Systole Commissures attachment point
Posterior
Anterior L R

21. LVOT 3-5 mm below BR
Diastole Systole

22. BASAL RING LEVEL
Diastole Systole

23. MIDDLE LINE THROUGH SINUS VALSALVA
Diastole Systole

24. COAPTATION LEVEL
Diastole Systole

25. SINOTUBULAR JUNCTION LEVEL
Diastole Systole

26. What can be done with the IVUS imaging modality?
Measurement of coronal and sagittal diameters at all level of aortic root
Definition of their changes during cardiac cycle
Measurement of ILT and definition of their changes during cardiac cycle
Measurement of the leaflets dimension and definition of their changes during cardiac cycle
Measurement and definition of changes of spatial structures surrounding the aortic root at all levels
Measurement of distances to the coronary arteries from different level of aortic root
Measurement of CA orifice diameter and its changes during cardiac cycle
Evaluation of degree and localization of calcifications

27. WHAT IT WILL GIVE
This direct and accurate measurement results will give possibility to provide the detailed description of aortic root anatomy and develop the definitions of aortic structures specifications, sizes and dynamics. It will facilitate the development of the guidance and standards of aortic root structures IVUS visualization as for healthy population as for patients with AS.
The knowledge of exact anatomy and dynamic of aortic root will assist not only in proper TAVI prostheses size selection with consequent minimization of complication rate related to patient-prostheses mismatch but also in further development of TAVI prostheses and extension of its use.

28. CONCLUSION
At this time no single imaging modality is preferred. There is no gold standard and thus it is not possible to define which method is the most accurate.
Variation in the reported annulus diameter with various imaging modalities suggests that further study of the factors involved in annulus sizing and development of new more accurate imaging modalities for TAVI are needed
The IVUS imaging modality (Vision PV8.2F) has all necessary theoretically demonstrated prerequisites to became the gold standard imaging modality for TAVI and facilitate not only the elimination of complications rate after TAVI but also further development of TAVI technique and prostheses.
It is necessary to perform the clinical investigations of the IVUS Vision PV8.2 implementation in the aortic root imaging and measurements with comparison analyses of obtained results with the respective results of other imaging modalities used for TAVI.