hao gao 1 , boyce e. griffith 2 , david carrick 3 , colin berry 3 , xiaoyu luo 1
DESCRIPTION
Hao Gao 1 , Boyce E. Griffith 2 , David Carrick 3 , Colin Berry 3 , Xiaoyu Luo 1. Fluid structure interaction of left ventricle modelling from diastole to systole based on in-vivo CMR. School of mathematics and Statistics, University of Glasgow, UK - PowerPoint PPT PresentationTRANSCRIPT
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
1. School of mathematics and Statistics, University of Glasgow, UK2. Department of Medicine, University of New York, USA3. Institute of Cardiovascular and Medical Science, University of Glasgow, UK
Challenges 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 19Immersed boundary method: https://code.google.com/p/ibamr
Image Derived LV Model
Healthy LV (at early of diastole) (1) Short-axis cine images
(2) Left ventricular outflow tracts
MVAV
LV
Manual Segmentation
Solid Reconstruction
3 out of 19
Image Derived LV Model
AV
MV
Remarks1: 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
inflowoutflow
Artificial extension
Image derived
4 out of 19
Myofibre-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 stress5 out of 19
Active Tension Model
Niederer S, et al, 2006
•Spatially uniform •simultaneous
6 out of 19
Boundary Conditions (1)
Contractile LV
Non-contractileValves
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
Boundary Conditions (2)
Contractile LV
Non-contractileValves
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
Boundary Conditions (3)
Contractile LV
Non-contractileValves
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
PWk(t): initialized with 85mmHg (cuff)
Rc
fully fixation Partial fixation
AV opens: out flow rate > 0AV closes: out flow rate < 0
Boundary Conditions (4)
Contractile LV
Non-contractileValves
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
Material 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 kPaothers from rat experiments
Results: Pressure-Volume Loop
60 80 100 120 140 160-20
0
20
40
60
80
100
120
140
160
180
200
LV cavity volume (mL)
LV c
avity
pre
ssur
e (m
mH
g)
diastolic filling
isovolumetric relaxation
isovolumetric contraction
ejection
12 out of 19
161mmHg
Cuff Pressure (85-150mmHg)
(78mL,0mmHg)
(143mL,8mmHg)
(139mL,119mmHg)
(72mL,95.7mmHg)
LV Dynamics
13 out of 19
Flow Patterns
60 80 100 120 140 160-20
0
20
40
60
80
100
120
140
160
180
200
LV cavity volume (mL)
LV c
avity
pre
ssur
e (m
mH
g)
14 out of 19
Aortic Flow Rates
15 out of 19
Validation: Strain Comparison
Middle LV
Red line: MR using deformable image registration methodBlack line: IBFE simulation
16 out of 19
Ongoing Work
(1) Coupling to electrophysiology
Mono/Bi-domain models
(2) Adding mitral valve
17 out of 19
Discussion & Conclusion
• The developed IB/FE LV model is capable of simulating LV dynamics with fluid-structure interaction
• Results are consistent with clinical measurements, a potential way to understand heart functions with new biomarkers
• Limitations
18 out of 19
Acknowledgement
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
Active Tension T
20 out of 22
Ca2+
T
Peak Systolic Active Tension
kPa
kPa
21 out of 20
basal
apex
Brief Introduction of IBM
Solid is immersed inside fluid (overlapped mesh)
22 out of 22
: fluid stress tensor: structure stress tensor
Stress tensor