法洛氏四重症術後之肺動脈流場型態分析

Analysis of flow patterns in pulmonary artery after repair of Tetralogy of Fallot

Hung-Lin Wang

June 14, 2006

Outlines

• Introduction & research motivations• Governing equations• Mesh design and boundary setup• Analysis of flow patterns• Results & discussion• Conclusions

National Taiwan University of Science and Technology

National Taiwan University of Science and Technology

What is Tetralogy of Fallot (TOF)? This group includes: • Pulmonary stenosis • A ventricular septal defect • Overriding aorta (the main blood vessel from t

he heart to the entire body is somewhat displaced)

• Right ventricular hypertrophy

Tetralogy of Fallot (problem)

National Taiwan University of Science and Technology

http://www.lpch.org/DiseaseHealthInfo/HealthLibrary/cardiac/tf.html

Fundamental assumptions

• A fluid in the pulmonary artery is blood, but a fluid in this study is considered to be Newtonian and incompressible.

• The gravitational effect is neglected.• No heat source and heat transfer in the flow

field.

National Taiwan University of Science and Technology

Governing Equations

• Continuity equation :

• Navier-Stokes equation :

0 u

uuuu

P

t

1

National Taiwan University of Science and Technology

Boundary Setup

National Taiwan University of Science and Technology

inlet

outlet

0 T

systolic diastolic

ρ= 1060 kg m‧ -3

μ= 0.003 kg m‧ -1 s‧ -1

LPA

MPARPA

outlet

b/f = Qb/Qf

Qb : Backward volume in a cycle

Qf : Forward volume in a cycle

Tang, T., Chiu, I.S., Chen, H.C., Cheng, K.Y. and Chen, S.J., 2001, Comparison of pulmonary aterial flow phenomena in spiral and Lecompte models by computational fluid dynamics. The Journal of Thoracic and CardiovascularSurgery 122, pp. 529-534.

Mesh Design

National Taiwan University of Science and Technology

Mesh Number : Mesh Number : 7290072900

Solid-WorksTM

CFD GEOM

CFD ACE

Model design

Mesh design

Boundary setup

National Taiwan University of Science and Technology

Analysis of flow patterns

National Taiwan University of Science and Technology

Tt10

28.5

National Taiwan University of Science and Technology

Tt10

76.5

National Taiwan University of Science and Technology

Tt10

72.6

National Taiwan University of Science and Technology

Tt10

16.8

National Taiwan University of Science and Technology

Tt10

08.10

National Taiwan University of Science and Technology

b/f = 0.009 b/f = 0.26

National Taiwan University of Science and Technology

The flow patterns at different diameters of LPA when b/f = 0.522

National Taiwan University of Science and Technology

Tt10

8.4

National Taiwan University of Science and Technology

Tt10

28.5

National Taiwan University of Science and Technology

Tt10

2.7

National Taiwan University of Science and Technology

Tt10

8.8

National Taiwan University of Science and Technology

Tt10

6.9

National Taiwan University of Science and Technology

Tt10

08.10

National Taiwan University of Science and Technology

b/f = 0.522

DL = 10 mm DL = 6 mm

National Taiwan University of Science and Technology

Analysis of 3D streamlines

National Taiwan University of Science and Technology

Tt10

28.5

National Taiwan University of Science and Technology

Tt10

16.8

National Taiwan University of Science and Technology

Tt10

12.9

National Taiwan University of Science and Technology

Tt10

08.10

National Taiwan University of Science and Technology

Results and discussion

National Taiwan University of Science and Technology

The results of b/f

The difference of netflow between LPA and RPA

National Taiwan University of Science and Technology

LPA angle(θ) = 107o LPA angle(θ) = 95o

National Taiwan University of Science and Technology

Effects of angle between LPA and MPA

National Taiwan University of Science and Technology

Variation of LPA and RPA b/f ratio with b/f of MPA

N : number of patientsbi : mesured valuepi : predicted value

519.0

RMSE Error, Square-MeanRoot :

National Taiwan University of Science and Technology

The relation of b/f in MPA and RPA

259.0

National Taiwan University of Science and Technology

The relation of b/f in MPA and LPA

717.1

Conclusions (1)

National Taiwan University of Science and Technology

• We use predicted flow patterns to explain why the b/f of LPA is higher than RPA. It is because the duration of regurgitation in LPA is longer than RPA.

• We can know if the b/f of MPA increases, so will b/fs of LPA and RPA.

• The difference of netflow between LPA and RPA is tiny when the b/f of MPA is low. On the contrast, the difference of netflow between LPA and RPA will increase if the b/f of MPA is raised.

• The b/f of LPA is higher than RPA both in this study and the mesured data of the hospital.

• The b/f of LPA will decrease if the angle between LPA and MPA increased.

• The variation of b/f ratio of LPA and RPA is not obvious when the b/f of MPA is greater than 0.2.

Conclusions (2)

National Taiwan University of Science and Technology

Thanks for your patience

National Taiwan University of Science and Technology