Coronary Artery Bypass Graft: Design, CFD Simulations, and Advantages/Disadvantages

Project scoping and planning

Table of Contents
Introduction...........................................................................................................................................2
Why doctor use......................................................................................................................................2
Design of a bypass graft........................................................................................................................4
What sort of blockage............................................................................................................................6
Introduce problems in patient................................................................................................................7
When to use bypass graft.......................................................................................................................8
Advantage and Disadvantage of a bypass graft.....................................................................................9
CFD simulations to optimise the design..............................................................................................11
Design.............................................................................................................................................11
Results.............................................................................................................................................11
Findings...........................................................................................................................................14
Research gap.......................................................................................................................................14
Conclusion...........................................................................................................................................15
References...........................................................................................................................................16
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Introduction
Coronary artery disease (CAD) is called as coronary heart attack disease. The large blood
vessel called coronary arteries which help the heart in getting oxygen. Basically, it supplies
blood to the heart and sometimes it becomes extremely narrow. As it becomes narrow the less
amount of blood can pass through the arteries and the heard does not get enough blood or
oxygen which can lead to chest pain, the problem in breathing while doing any physical
activity. If these blood vessels get completely blocked, it may cause a heart attack. It also
makes the heart muscle weak and can lead to failure of heart or heart rhythm problems
(UCSF, 2018). It is determined that when the heart not able to pump blood properly to the
rest of the body then it results in failure of the heart. A rhythm problem means any change in
the normal beating pattern of the heart.CAD starts from having chest pain and breathing
problems like shortness in breathing. This type of pain is also known as angina. It is related to
having a feeling of becoming narrower or nervousness and may expand to the back of the
neck, upper abdomen, back, the arms or jaw. All these symptoms can be noticed while doing
any physical activity as heart muscle requires more oxygen during this time. It happens
because not enough blood and oxygen reaching to the heart through the coronary arteries
(Dauerman, 2013). This can be referred to the "angina threshold" when the symptoms start
occurring after reaching to the defined level of the physical activity. Arteriosclerosis is the
reason for coronary artery disease. Arteriosclerosis starts developing from slight swelling in
the wall of the blood vessel. It gets narrowed or blocked because fats, cells and other material
get attached to the walls of the blood vessel and it is called plaques. In the beginning, it's hard
to notice the deposits of the coronary arteries. And if it continues to get increasing then it
might start influencing the flow of blood through coronary arteries, till the part of the heart
not able to get enough oxygen. Chest pain and discomfort might be arising during physical
activity or emotional stress (Major Satisha T S et al., 2012).
Why doctor use
The Coronary Artery Bypass Graft (CABG) is considered to be a surgical process carried out
by the doctors for restoring the flow of blood for delivering nutrients and oxygen to the heart
muscle. The cardiac surgeon in the CABG develops new route by bridging stenosed artery
with a vessel. The bypass graft is affected because of the poor hemodynamics in intimal
hyperplasia. Blood’s hemodynamics changes the atherosclerosis condition such as wall shear
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stress, WSS spatial gradient and oscillatory shear index (Do, 2012). The hemodynamic
parameters are influenced powerfully by conditions of flow that are dependent mostly on the
geometry of the artery. The parameters are being used for examining the sternness of the
coronary stenosis disease. The computational fluid dynamics (CFD) model is being used by
the doctors for showing the pattern of blood flow in various anatomical geometries. CFD
simulation of the hemodynamic is considered to be very much in the research of the flows of
biological fluid.
In the clinical applications, imagining techniques are used for providing only the anatomic
Coronary artery disease. The pressure data and flow rate information of coronary artery
disease can be identified by MRI and angiography method. CFD analysis can be used to
determine hemodynamic information and data of coronary heart disease. The application of
computational fluid dynamics method assists to examine the hemodynamic strictures of the
coronary heart disease (Dur et al., 2010). However, it is found that Coronary Artery Bypass
Graft fails after a short time period because within the junction of the bypass graft a plaque is
developed which is referred to as intimal hyperplasia. The intimal hyperplasia development
within the bypass graft leads to compliance mismatch and abnormal hemodynamic. Thus, it is
necessary to understand and analyse the hemodynamic forces into the coronary artery bypass
and its geometrical characteristics and mechanical structure.
In vivo, it difficult to obtain the information and in vitro numerical and experimental
investigations of realistic and idealistic CABG surgery models have been used extensively for
obtaining the mechanical and hemodynamic forces in the bypass. The result is being used for
designing and optimising the configurations of bypass graft because the development of
artery diseases decreases and increase in the patency of bypass. Computational fluid
dynamics is being used extensively as a numerical tool for investigating geometrical and
physical factors that influences the hemodynamic of different CABG configurations. The
flow characteristic and pressure and wall shear stress for cyclic and steady flows with CFD
can be effectively and accurately examined (Ellis and Holmes, 2015).
The use of CFD in hemodynamic and biomechanics is accepted widely as an appropriate
alternative in vivo and vitro measurements that can be very time to consume and expensive.
There is always a requirement for obtaining effective quantitative experimental data for
validation and verification of the numerical predictions. The combination of CFD with
imaging and experimental methods has been widely used for examining the hemodynamic of
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