Simulation of Coronary Artery Bypass Graft using Computational Fluid Dynamics

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Introduction
Coronary artery disease is commonly referred to as coronary heart attack. Coronary artery refers
to the large vessel that normally supplies the heart with blood that is rich in oxygen and nutrients.
Although its primary function is the supply of the blood to the heart, it is affected by the
presence of chemicals that normally results in its narrowness. When this kind of blood vessel
becomes very narrow, the supply of blood to the heart becomes affected considering that not
much blood supply will be reaching the heart as required. This phenomenon is common when the
individual is subjected to a lot of physical activities or physical exercise(Kabinejadian and
Ghista 2012).
Complete blockage of this blood vessel results in a heart attack. The other effects are that the
muscles of the heart become very weak and the rhythm of the heartbeat is affected too. This may
possibly lead to heart failure. The failure of the heart is determined by its inability to supply
blood to the best parts of the body. The signs of heart failure begin with the experience of pains
in the cheat which is commonly known as angina. All the above-illustrated symptoms are
normally noticed when one is subjected to a lot of exercises(Passerini et al.2014). Other relates
symptoms of heart attack include having back pains, pain in the upper abdomen and arms. The
occurrence of pain is as a result of little blood passing through the coronary artery.
Risk of growth of plaque
The occurrence of these symptoms will always target the threshold point called angina
threshold. It is after this threshold that the supply of blood through the vessels is restricted. The
most common cause of heart disease is called arteriosclerosis. This kind of disease starts
developing just as a small swell in the blood vessel walls. As the fats continue getting deposited,

the walls of the vessels become blocked. The fat deposits on the wall of the blood vessel form a
substance called plaque. The formation of the plaques is not usually noticeable at the initial
stages. Its influence on the flow of the blood in the coronary artery will be felt once it becomes
bigger or of reasonable size. When the patient is subjected to emotional stress or strenuous
exercise, the chest pain symptoms start to manifest. One of the viable procedures or the treatment
of the disease is called computational fluid dynamics.
This is basically pre-surgical planning that is capable of evaluation and calculating local
hemodynamics. The introduction of this technique was actually done recently. The technique
allows for the analysis of the dynamics of the flow in details. The technique employs a 3-D
model, WSS and total pressure as the parameters from the patient of specific computed
tomography. When this particular technique is used, detailed hemodynamic in the virtual
situation, post-operative cardiovascular surgical states and intraoperative can be visualized. The
ideas behind the CFD model were to allow for the enactment of limited volume strategies. This
was to aid the physiological pulsatile stream that includes a reflection of the fringe wave,
direction of the self-ruling framework and the impedance of trademark. The wall shear stress and
the Oscillatory shear Index was obtained among the cardiovascular cycle. The discoveries have
demonstrated that simulation by the use of a computer which has numerical optimization has
very many advantages including the provision of the cost-effective techniques for the structure of
the medical devices.
Literature review

Coronary Artery Bypass Graft is normally regarded as a process of surgery that is carried out by
the professionals or medics to restore the flow of the blood in the coronary artery. This allows
the blood vessel to be able to deliver the blood that rich in nutrients and oxygen to the muscle of
the heart. The surgical activity involves the creation of a new route that will bring in a bridge
system of the stenosed artery. One of the devastating effects or challenge is that the graft is
affected as a result of poor hemodynamic intimal hyperplasia. The condition of the
atherosclerosis is changed by blood hemodynamics which may include wall shear stress,
oscillatory shear index and WSS spatial gradient. The parameters of the hemodynamics are
influenced by the conditions of the flow which are also dependent on the geometry of the blood
vessel.
The sternness of coronary stenosis disease is usually determined by the use of the illustrated
parameters. The results that are obtained by the use of the model of computational fluid dynamic
illustrates blood flow pattern in different geometries of the anatomical. In the cases of the clinics,
this kind of technique is only used to provide anatomic coronary disease of the artery. The
identification of the pressure data and information regarding the flow rate can be done by the use
of angiography and MRI methods. The information and data of the coronary heart disease can
actually be determined by the analysis of CFD on hemodynamics(Kokalari, Karaja. and Guerrisi
2013).
The determination of the hemodynamic strictures of coronary heart disease can be achieved by
the use of the method of computational fluid dynamics. This will allow for the determination of
the flow characteristics, wall shear stress and the actual pressure in the cycle. The effects may
extend to the steady flow within the blood vessel itself. The results that re-obtained, in this case,
are very accurate and effective. They can, therefore, be used in the design and optimization of

the configuration of the bypass graft. This is because the development of artery disease tends to
reduce an increase in the patency of the bypass.
The models of CABG surgery have been used on very many occasions to obtain the forces that
are involved in the hemodynamic bypass. The investigation of the physical and geometrical
factors that affect the hemodynamic configuration is normally done by the use of computational
fluid dynamics as a numerical tool(Müller, Fedosov and Gompper 2014). When two methods
that are complementary are used, determination of factors like ingredients, blood flow fields,
wall shear stress, artery junction and deformation of the graft. When these factors are properly
evaluated, it is possible to obtain the degree of mismatch in flow compliance. Also, most
researchers have carried out extensive research work to determine the quantity of the velocity
profiles and to quantify the wall shear stress distribution in a true model. This has been done by
the comparison of data from a magnetic resonance also called MR imaging scanning and through
simulation of CFD simulations. The outcome that had been shown was actually the quantitate
results from the expected MR estimation and the example of the stream.
The stressing of the hemodynamic bypass graft can be done by the use of the information
extracted from the patient. This data is obtained tomography angiography that has been
computed. The model of the 3-D is normally treated as a rigid wall for the demonstration or for
the simulation of the flow of the blood in the blood vessels. This result may not be appropriate
for the recognition of the transition of the flow physics to the turbulence of the downstream in
the curvature of the graft(Tan,Thomas and Liu 2012). The study concentrated on the new
technique implementation that will actually allow for the growth of the prospective vascular
models with the use of the system that is simulation based.

There is normally the use of a computer-aided design that has the concept of computational fluid
dynamics techniques to optimize the hemodynamics of the coronary artery bypass graft(Moireau
et al 2012). CABG configuration is relied upon for the hypothesis of surgical planning and it is
used for the evaluation of local and acute hemodynamic.This facilitates the adjustment of
coronary bypass surgery. The result showed that the procedure could be useful in decision
making during the processes of surgery. There is a proximal anastomosis of the saphenous vein
graft to aorta and stenosis in the lower section of the right coronary artery. The internal
mammary artery that is created from the aorta is anastomosed to the left coronary artery that is
descending. It is seen that after task amid the main year roughly 10-15 percent of the vein unites
stops. For five to a multi-year, about portion of vein join supposedly is compelling.
Following 10 years, around 60 percent of the vein graft is evident and 50 percent stay free of
critical stenosis. The real reason for the event of graft stenosis is observed to be IH. IH is the
strange, excess and multiplication of the plane muscle cells in light of brokenness or endothelial
damage. There are both biomechanical and natural variables which lead to IH. Hemodynamic
parameters are critical data of IH and their start. IH prevalently begins at the start of the vein and
anastomosis branch intersection where the hemodynamic factors and examples of the conveyed
stream are observed. The dissemination examples of the stream, hemodynamic components, and
intimal reasoning ratios are connected with the movement and beginning of anastomotic intimal
hyperplasia and atherosclerosis. The upgrade of the patency rate and life span of CABGs will
improve the launch portion and left contractility ventricular record of patients with the coronary
artery illness.
This will be the end of the need of re-activity, lowered grimness and diminished restorative
expenses. Coronary artery disease is the deterrent or contracting of the coronary artery which is