Hao Gao 1 Boyce E Griffith 2 David Carrick 3 Colin Berry 3 Xiaoyu Luo 1 School of mathematics and Statistics University of Glasgow UK Department of Medicine University of New York USA ID: 796625
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Slide1
Fluid structure interaction of left ventricle modelling from diastole to systole based on in-vivo CMR
Hao Gao1, Boyce E. Griffith2, David Carrick3, Colin Berry3, Xiaoyu Luo1
School of mathematics and Statistics, University of Glasgow, UK
Department of Medicine, University of New York, USA
Institute of Cardiovascular and Medical Science, University of Glasgow, UK
Slide2Challenges in LV Modelling
Multi-scale: Computer simulation offers unique opportunities for integrating multi-sets data, providing insights, even predicting outcomes, etc.
Multi-physics:
Patient specific:
2
out of 19
Immersed boundary method:
https://code.google.com/p/ibamr
Slide3Image Derived LV Model
Healthy LV (at early of diastole)
(1) Short-axis cine images
(2) Left ventricular outflow tracts
MV
AV
LV
Manual
Segmentation
Solid Reconstruction
3
out of 19
Slide4Image Derived LV Model
AVMV
Remarks
1: No valves (with positions indicated);
2: Regions above MV and AV are artificially constructed for outflow and inflow BCs;
3: circular inflow and outflow shapes (easy for applying BC)
Basal plane
apex
inflow
outflow
Artificial extension
Image derived
4
out of 19
Slide5Myofibre-enforced Structure
Laminar organization: Fibre—sheet—normal (f, s, n)
Hunter,
Brieings in Bioinformatics
, 2008
Fibre
sheet
Sheet-normal
Holzaple
& Ogden 2009
shear
sheet
fiber
matrix
8 unknown parameters
Passive stress
5
out of 19
Slide6Active Tension Model
Niederer S, et al, 2006
Spatially uniform
simultaneous
6
out of 19
Slide7Boundary Conditions (1)
Contractile LV
Non-contractile
Valves
Inflow/outflow
Ramped P (8)
Only allowing radial expansion
Fixed in long and circumferential axis
fixed
fully fixation
Partial fixation
7
out of 19
BCs for diastolic filling
Note: Diastolic pressure is directly applied to the endocardial surface to mimic the first sucking phase of the diastolic filling.
No flow
diastolic filling
isovolumetric
relaxation
isovolumetric
contraction
ejection
Slide8Boundary Conditions (2)
Contractile LV
Non-contractile
Valves
Inflow/outflow
Only allowing radial expansion
Fixed in long and circumferential axis
fixed
8
out of 19
BCs for
isovolumetric
contraction
No flow
diastolic filling
isovolumetric
relaxation
isovolumetric
contraction
ejection
No flow
fully fixation
Partial fixation
Slide9Boundary Conditions (3)
Contractile LV
Non-contractile
Valves
Inflow/outflow
Only allowing radial expansion
Fixed in long and circumferential axis
fixed
9
out of 19
BCs for ejection
diastolic filling
isovolumetric
relaxation
isovolumetric
contraction
ejection
No flow
Rp
C
P
Wk
(t): initialized with 85mmHg (cuff)
Rc
fully fixation
Partial fixation
AV opens: out flow rate > 0
AV closes: out flow rate < 0
Slide10Boundary Conditions (4)
Contractile LV
Non-contractile
Valves
Inflow/outflow
Only allowing radial expansion
Fixed in long and circumferential axis
fixed
10
out of 19
BCs for
isovolumetric
relaxiation
No flow
diastolic filling
isovolumetric
relaxation
isovolumetric
contraction
ejection
No flow
fully fixation
Partial fixation
Slide11Material Parameter Optimization
Published material parameters
Passive material parameters
Diastolic filling
Matched ED volume
No
Adjust parameters (scale + fine adjust)
Systolic contraction
Matched ES volume
End
Adjust
Tref
No
11
out of 19
Tref
= 256
kPa
others from rat experiments
Slide12Results: Pressure-Volume Loop
diastolic fillingisovolumetric relaxation
isovolumetric
contraction
ejection
12
out of 19
161mmHg
Cuff Pressure
(85-150mmHg)
(78mL,0mmHg)
(143mL,8mmHg)
(139mL,119mmHg)
(72mL,95.7mmHg)
Slide13LV Dynamics
13
out of 19
Slide14Flow Patterns
14
out of 19
Slide15Aortic Flow Rates
15 out of 19
Slide16Validation: Strain Comparison
Middle LV
Red line: MR using deformable image registration method
Black
line
: IBFE simulation
16
out of 19
Slide17Ongoing Work
Coupling to electrophysiologyMono/Bi-domain models
(2) Adding mitral valve
17
out of 19
Slide18Discussion & Conclusion
The developed IB/FE LV model is capable of simulating LV dynamics with fluid-structure interactionResults are consistent with clinical measurements, a potential way to understand heart functions with new biomarkersLimitations 18 out of 19
Slide19Acknowledgement
Collaborators:
R. W. Ogden
B. Griffith
W.W. Chen
J. Ma
N Qi
H. Gao
W.G. Li
A. Allan
H.M. Wang
C. Berry
19
out of 19
Slide20Active Tension T
20 out of 22
Ca
2+
T
Slide21Peak Systolic Active Tension
kPa
kPa
21
out of 20
basal
apex
Slide22Brief Introduction of IBM
Solid is immersed inside fluid (overlapped mesh)
22
out of 22
: fluid stress tensor
: structure stress tensor
Stress tensor