Monash Uni - Final Year Project Presentation

1. FINITE ELEMENT
MODELING OF A LEFT
VENTRICLE & HEART
PATCH
Presented by : Han Yee Lee
Supervisor: Dr Wenyi Yan

2. Presentation Outline
•Background
/ Motivation
•Objectives
•Methodology
•Results
/ Discussion
•Conclusion
•Future recommendations
http://wayoffside.files.wordpress.c
om/2007/11/heart.jpg

3. Background / Motivation
The human heart
weights around one
pound
The heart beats
approximately 70
times a minute and
100,000 times a day
http://www.livescience.com/images/human_heart_graphic_03

4. • Cardiac Cycle

Cardiac cycle is a sequence of mechanical events of
the heart pumping blood through our body

The heart pumps blood to the lungs, back to the
heart, out to the body and back to the heart again in
about 23 seconds
http://www.youtube.com/watch?v=_YuX7CtClyg&feature=related

5. • Myocardial Infarction
Myocardial Infarction is
a medical term for a
heart attack
Myocardial infarction is
a death of heart muscle
from a sudden blockage
of a coronary artery
http://www.healthcentral.com/common/images/1/18
048_3691_5.jpg

6. http://www.asir-journal.com/content/3/1/6/figure/F1?highres=y

7. • Heart Patch Strategy
 Developed
during
the mid 1990s
 Serves
two function:
-Cell delivery
-Left ventricular
restraint
 Heart
Patch could
decrease the heart
wall stress
Chen et al 2008 ‘Characterization of a Soft
Elastomer Poly designed to match the
mechanical properties of Myocardial Tissue’

8. http://www.asir-journal.com/content/3/1/6/figure/F1?highres=y

9. Objectives
 The
primary objectives of this
research are
1) Model a healthy dog’s left ventricle
2) Model an infarct dog’s left ventricle
3) Implement the heart patch strategy
onto the infarct left ventricle

10. Methodology
 Continuity
6 is a problem-solving
environment for finite element analysis in
bioengineering and physiology
 Finite
1)
2)
3)
4)
element modeling steps:
Geometry
Boundary Conditions
Material properties
Solving

11. • Geometry
Healthy Model
 Prolate
spheroidal
coordinates(λ,v,θ)
 consists
of 210 nodes
and 150 elements
• Boundary conditions
 There
are 3 rigid body
motions
 Ensure all rigid body
motions are
suppressed
http://en.wikipedia.org/wiki/Prolate_spheroidal
_coordinates

12. Infarct Model
Infarct Patch Model
t = 1.1mm

13. •Material Properties
 Material
based on Constitutive Law
(Transversely Isotropic & Hyper Elastic
Material )
Left Ventricle’s Parameters
Healthy
Infarct Section
Patch
Stress Scaling Coefficient (kPa)
0.14638
2.9
0.14638
Fiber Strain Coefficient
67.069
33.17
67.069
Transverse Strain Coefficient
26.571
41.56
26.571
Bulk Modulus
100
100
1000
Fiber_Trans_Shear_coefficient
21.604
21.604
21.604
•Pressure
A pressure increment of 1kPa is being
applied in the inner surface of the left ventricle

14. Results & Discussion
•Deformed Geometry
Internal Pressure = 0 kPa
Internal Pressure = 1kPa (7.5mmHg)
When the left ventricle contracts (filling
state), there is a change in volume from 26ml40ml

15. •Fiber Stress across the
ventricular thickness at the
 Healthy
Section
 Infarct
Section
 Infarct
Patch Section
Healthy Section
Infarct Section
Infarct Patch Section

16. Healthy versus Infarct versus Infarct Patch
section (1kPa Internal Pressure)
8
6.90
Healthy
section
Fiber Stress (kPa)
7
6
5.98
5
Infarct
section
3.81
4
3.90
3
2.47
2
1
0
0.56
Infarct
Patch
section
0.60
0.58
0.60
0.62
0.64
0.66
0.68
0.70
Longitudinal coordinates
•Approximately there is a 76% increase of stress at the
infarct section
•Approximately there is a 13% decrease of stress at the
infarct section when the patch is applied

17. •Fiber Stress along the
ventricular wall
 Healthy
 Infarct
versus Infarct Model
Model versus Infarct Patch Model

18. Healthy Model
•Average Fiber Stress =
12.36 kPa
Infarct Model
•Average Fiber Stress =
13.55 kPa

19. Infarct Patch Model
•Average Fiber Stress =
13.2 kPa
Infarct Model
•Average Fiber Stress =
13.55 kPa

20. Conclusion
 Fiber
stress at the ventricular thickness
-Approximately 76% increase of stress (infarct)
-Approximately 13% decrease of stress (patch)
 Fiber
stress along the ventricular wall
-An average of 1.2kPa fiber stress increased (infarct)
-An average of 0.35kPa fiber stress decreased (patch)
The heart patch strategy WORKS!!!

21. Future Recommendations
 Different
material properties for the
patch
 Increase
the size of the patch
 Results
comparison with previous
research
 Consider
the ‘relaxation state’ for the
left ventricle

22. QUESTIONS