Image-based modelling of blood flow in the human coronary arteries

Ashkan Javadzadegan 1

Supervisors: Masud Behnia 1 & Leonard Kritharides 2

1 Fluid Dynamics Group, School of Mechanical Engineering, 2 Concord Repatriation Hospital

Contents

Significance

Image acquisition and geometry reconstruction

Computational fluid dynamics

References

Significance

Coronary arteries are attached to the heart and most of the heart attacks are because of the coronary artery disease

Image acquisition andgeometry reconstruction

3D acquisition system

Image acquisition andgeometry reconstruction

AB

A

B

Stored Slices

Original contours Surface mesh fitted

x

y

zxz

y

Vessel centralaxis

Surface reconstruction

Image acquisition andgeometry reconstruction

Computational fluid dynamics

Computational fluid dynamics simulation

Mesh Generation

Boundary Conditions

Flow Solver & Post Processing

An important task

May take weeks or months One desires to perform computations for a real

patient geometry How do you determine real shapes & dimensions?

Using appropriate boundary conditions in order to get realistic results

Today a number of methods are available to solve the Governing Equations

Some researchers write their own codes for the purpose

Use of commercial codes is also wide spread –Fluent (ANSYS), Star CD, CFX etc

Computational fluid dynamics

Mesh Generation

Discretization of coronary artery into tetrahedrons whose size and distribution largely govern the accuracy of numerical simulation

Computational fluid dynamics

Boundary Conditions

proximal and distal pressures are measured using three dimensional coronary angiography and are used as inlet and outlet boundery conditions for numerical studies.

Distal Pressure

Proximal

Distal

Proximal Pressure

Computational fluid dynamics

Flow Solver Today a number of commercial CFD codes are available to solve the governing equations, Ansys CFX is one of them.

Post ProcessingThe flow solver yields several MB or GB of data depending upon the flow

The data has to be analyzed and rendered as Graphs, Charts, Tables, Vectors and contours

The Flow Solvers usually have the post processors incorporated Separate processors – TECPLOT etc. are available

References

Asakura T, Karino T. Flow patterns and spatial distribution of atherosclerotic lesions in human coronary arteries. Circ Res. 1990;66(4):1045-1066.

Yamagishi M, Terashima M, Awano K, Kijima M, Nakatani S, Daikoku S, Ito K, Yasumura Y, Miyatake K. Morphology of vulnerable coronary plaque: insights from follow-up of patients examined by intravascular ultrasound before an acute coronary syndrome. J Am Coll Cardiol. 2000;35(1):106-111.

Yong ASC, Ng ACC, Brieger D, Lowe HC, Ng MKC, Kritharides L. Three-dimensional and two-dimensional quantitative coronary angiography, and their prediction of reduced fractional flow reserve. Eur Heart J. 2011;32(3):345-353.

ANSYS, ANSYS CFX-Solver Theory Guide. 2010, Canonsburg, PA