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Image Assistance in TAVI
Why CT ?
Won-Jang Kim, MD, PhD
Clinical Assistant Professor of Medicine, Heart Institute,
A
Asan
M di l C
Medical
Center,
t S
Seoul,
l K
Korea
Major Uses of CT in TAVI
• Ileofemoral
Sytem : & Planning
PatientArterial
Selection
Size, Calcification, Tortuosity, Plaques
• 3D annular & root morphology & dimensions
• Amounts of calcium in valve
D ori puncture
During
Implantation
I
lsite t(TA)
ti
• Optimal angle (TF)
• Relationship of annulus to both coronary ostia
• Merging Image during Implantation
• Post TAVI assessment
Follow-up
Evaluation of Access
Routes
Ileofemoral Artery Evaluation
Ileofemoral Artery Evaluation
Size Measure, Calcium distribution, Tortuosity,,,
Vascular
ascu a Complications
Co p cat o s
Potential risk factors
• Patient related
• Device related
-
Vessel Size
Calcification
Tortuosity
Vessel stenosis
Plaque
CT
Can
- TAVI system
- Sheath
- Guide wires
- Balloon
- Closure device
Predict
• Technique/operator related
- Aggressive manipulation
- Inaccurate calibration and
measurements
- Poor control
- Prolonged procedural time
Femoral Artery
y Puncture under
Fluoroscopic Guidance
Anterior
superior
iliac spine
Inguinal
skin crease
Femoral
head
Puncture site, CFA
Profunda
femoral
artery
Inguinal
g
ligament
Common
femoral
artery
t
Superficial
femoral
artery
Initial Ileofemoral Aortography
Made by Adw 4.5, GE healthcare system
Baseline Angiography & CT
Made by Adw 4.5, GE healthcare system
Difficulty in Advancement
S
Severe
calcific
l ifi small
ll vessell
Various Access Sites
Transaortal
Transsubclavian
Transapical
T
Transfemoral
f
l
Annulus sizing
Cannot be emphasized enough…
Clinician Publications: Imaging
1. Sizing is an important part of pre-case
planning for TAVI
2. Most current literature suggests a multimodality approach and many prefer 3D
method (MSCT)
Paravalvular Leak
Sizing and calcification are being
investigated
g
as major
j determinants of
TAVI outcomes, for both Medtronic
CoreValve® & Edwards Sapien®
Device size selection cannot be emphasized enough
Anatomy of Aortic Valvar
Complex
Stability of valve
probably
d t
determined
i d by
b the
th
“virtual ring”
Aortic Root thus composed of 3 rings and
one crowncrown-like ring
Piazza, N. et al. Circ Cardiovasc Intervent 2008;1:742008;1:74-81
Device Sizing
g Can Impact
p
Procedural
Outcomes
• Significant variation exists in TAVI device
selection
• Imaging modality differences
• Definition of aortic annulus
• Industry differences
• Physician preference and experience
• The aortic annulus is a non-circular
non circular structure
and proper imaging is important
• Several p
publications have demonstrated a
correlation between sizing and clinical
outcomes
Aortic Annulus on CT
Mean = 1.29 ± 0.11
Circular Annulus is Very Small Proportion
Distribution of Dmax/Dmin from 164 TAVI patients
Courtesy of Dr. Piazza and Prof. Lange, German Heart Center, Munich Germany
A Limitation of Echo
c
?
It is possible a true diameter is not measured due
to the imaging plane acquired
Piazza N, et al. Circ Cardiovasc Intervent. 2008;1:74.
Low Correlation Between Echo & CT
MEAN DIAMETER
162 patients  Low correlation between echo diameter and all CT derived
measurements (major, minor, & mean diameters, perimeter, and area)
Courtesy of Dr. Piazza and Prof. Lange, German Heart Center, Munich Germany
CT is Highly Reproducible Compared to
Echo
Echo
MSCT
Tzikas A, et al. Catheter Cardiovasc Intervent. 2011;77:868.
Aortic Annulus on MSCT
Coronal measurements do not equal those from the
annular plane
MPR
Oblique Coronal Image
Coronal Image
Aortic Annulus
Aortic Annulus on MSCT
Sagittal measurements do not equal those from the
annular plane
MPR
Oblique Sagittal Image
Sagittal Image
Aortic Annulus
The Aortic Annulus on MSCT
Aortic
Annulus
RVOT
RA
LAA
Descending
A t
Aorta
LA
New CT Parameters
Area-derived virtual Diameter
√(4*Area/π)
√(4
Area/π)
Area
Minimum
Diameter
Elli ti it Ratio
Ellipticity
R ti
Maximum Diameter/
Minimum Diameter
Perimeter
Perimeter-derived virtual Diameter
Perimeter/π
Maximum
Diameter
CT Measurements of Aortic Annulus
Perimeter: linear distance of tracing
g around
the aortic annulus
Area: area contained within
Area
ithin tracing aro
around
nd
the aortic annulus
Major & Orthogonal Minor Diameters:
linear distances through
g the center of the
aortic annulus
Mean Diameter: Calculated mean of major
and minor diameters
TEE vs CT (N=30)
TEE
AMC data
3-Chamber
3
Chamber
Coronal
Basal Mean
Area-derived
Rule of sine
20.3±2.1
22.5±1.9
22.6±2.0
22.6±2.0
24.5±2.7
20.4±1.6
Inter-Readerfor
Reliability
byusually
ICC (N=30)
• CT measurements
annulus are
larger than
3-Chamber
Coronal
echocardiography
0.75 (0.63-0.80)
0.51 (.40-0.62)
Basal Mean
Area-derived
Rule of sine
0.80 (0.70-0.85)
0.81 (0.71-0.89)
0.81 (0.72-0.88)
Perimeter
0 86 (0
0.86
(0.79-0.92)
9 0 92)
Intra-Reader
ReaderCT
Reliability
by ICC
(N=30)
30)
• MostIntra
reproducible
measurements
are(N
perimeter
perimeter,
3-Chamber
1
2
Coronal
Basal Mean
Area-derived
Rule of sine
0.93(0.84-0.97)
0.95(0.88-0.97)
0.96(0.89-0.99)
0.93(0.83-0.96)
area-derived,
basal mean,
and rule0.95(0.88-0.98)
of sine method
0.72(0.47-0.88)
0.89(0.76-0.94)
0.94(0.84-0.96)
0.94(0.85-0.97)
0.51(.40-0.62)
Perimeter
0 97(0 93 0 98)
0.97(0.93-0.98)
0.95 (0.86-0.98)
IIC, Intraclass correlation coefficient
Anatomic Implications for TAVI
I
Imaging
i
• The aortic annulus is clearly a complex
q
imaging
g g that can take
structure and requires
into account its elliptical and irregular shape
• Single diameter sizing methods can provide
misleading results
• 3D imaging can provide a more accurate
representation of the aortic annulus
What to do with CT annular
measurements
t currently?
tl ?
• Multidisciplinary approach - team members from
the interventional and surgical
g
teams reviewing
g
aortic annuli with the CT and echo teams
• Root geometry and annular configuration by CT
affords the implanting physician greater
understanding of the patient’s anatomy and allows
for a more individualized TAVI approach
What are the current
recommendations?
Annulus size by TEE
26mm Valve
23mm Valve
Usually tend to oversize by at least 2mm on echocardiography
CT Sizing for CoreValve
Valve Size
Diameter
Perimeter
Cover Index
31mm
31mm
31mm
31
31mm
29mm
28mm
27mm
26
26mm
91.1
88
84.8
81 7
81.7
6.45%
10.30%
12.90%
16 13%
16.13%
29mm
29mm
29mm
29mm
27mm
26mm
25mm
24mm
84.8
84
8
81.7
78.5
75.4
6.90%
6
90%
10.30%
13.80%
17.20%
26mm
26mm
26mm
26mm
23mm
22mm
21mm
20mm
72.3
72
3
69.1
66
62.8
11.50%
11
50%
15.40%
19.20%
23.10%
CT Sizing
g for Edwards Valve
Annular Area (mm2)
Edwards valve size (mm)
230 - 300
20
310 - 320
20 or 23
330 - 400
23
410
23 or 26
420 - 510
26
520
26 or 29
530 - 660
29
Aortic root dimension and spatial
relationship with surrounding
structures
LM
RCA
From annulus to LMCA
LV
From annulus to RCA os
Navigator For Transapical Approach
Direction of Puncture or Wire
Made by Adw 4.5, GE healthcare system
Aortic Valve Morphology
& Amount of Calcium
Scanty calcium
Heavy eccentric calcium
Vague Number of Leaflet
TTE
R/O Bicuspid AV
It is clearly Tricuspid Valve
Made by Adw 4.5, GE healthcare system
Echocardiographic findings
It is hard to deterimine how much calcium is in valve
TEE
TTE
Lack of Calcium
It is risk factor for migration or annulus rupture
Heavy Eccentric Calcium
Heavy Eccentric Calcium
Heavy calcium on non-coronary cusp
Made by Adw 4.5, GE healthcare system
Heavy Eccentric Calcium
Basal portion
Top of valve
Made by Adw 4.5, GE healthcare system
Valve Position & Implantation
p
LAO 1 CAUD 26 ; 26mm Valve
Final Aortogram
Echocardiographic evaluation
Mild to moderate PVL,
No severe AR sign in pressure curve
Sudden Drop of Vital Sign,
Embolized valve to LVOT
Major
j Operation
p
Removal of embolized Edwards valve
AV Replacement (Magna 21 mm)
Patient was cared in ICU.
Valve positioning
p
g
Line of Perpendicularity- Predicted
A l
Angles
Aortic Valve Plane by CT Scan
RCC
LCC
NCC
LAO Cranial
RAO Caudal
LCC
RCC
NCC
RAO Caudal
LAO Cranial
Merged
g
Imaging
g g Tools
Courtesy by Philips
Follow up evaluation
Examples of Conformability
CoreValve Cases
Volume Rendering
g Image
g
LM
RCA
Made by Adw 4.5, GE healthcare system
Spatial relationship with
surrounding structures
Coronal View
LM
RCA
Made by Adw 4.5, GE healthcare system
Spatial relationship with
surrounding structures
Sagittal View
LM
Made by Adw 4.5, GE healthcare system
Double Oblique
q
View
No Valve Migration, Fracture, Circumferentiality
New Imaging Modalities
using the CT image
DynaCT
y
Image
g Acquisition
q
with
rapid pacing
C
Courtesy
t
Siemens
Si
S
Systems
t
Valve deployment under DynaCT
Edwards SAPIEN
CoreValve
Courtesy by Alois Nöttling Siemens
Courtesy by Brockmann German Heart Center Munich
Conclusion: Why CT?
• CT is the only 3D method that:
- Allows for several measurements of the aortic
-
annulus, including perimeter.
Allows for complete patient assessment,
including access routes (femoral
(femoral, subclavian,
subclavian
or direct aortic).
Allows for calcification assessment.
• MRI is limited by spatial resolution and calcification
assessment is limited. Plus it is a more technically
challenging technique to get the correct images.
Better for hemodynamic evaluation (reconstruction
can be challenging),
g g), flow
• 3D echo is limited by spatial resolution,
calcification,, and does not readilyy allow for the
assessment of access routes