Numerical Study On Hemodynamics Of Cardiovascular Surgical Planning

Hemodynamic factors directly impact on vascular endothelial cells, and playimportant roles on the physiological and pathological function of endothelial cells. Ithas been found that abnormal or uneven hemodynamic factors, including the flowseparation, vortex, high pressure, low wall shear stress, oscillatory shear stress, longparticle residence time, second flow and so on, always appear at the artery bifurcation,bending and valve. These abnormal hemodynamic factors, which are also calledatherosclerotic-dangerous hemodynamic factors, can cause arterial intimal hyperplasiaor endothelial cell damage, and lead to the formation of atherosclerotic plaque nearthe wall. Therefore, these factors have been widely thought to be closely related withthe cause and development of arterial diseases.Except for the above-mentioned areas, dangerous hemodynamic factors are alsoobserved at the cardiovascular bypass regions. These factors can cause intimalhyperplasia at local bypass regions and result in post-operational restenosis or graftdiseases, which have serious influences on the surgery and long-term effectiveness.Therefore, hemodynamics must be considered in the cardiovascular surgery.Cardiovascular surgical planning is trying to optimize the post-operationalhemodynamics and assist surgical decisions before the surgery by predicting andevaluating the hemodynamics of possible surgical options based on the principle ofavoiding dangerous hemodynamic factors.Three cardiovascular diseases, including single ventricle heart defect, tetralogy ofFallot and coronary artery stenosis, were studied with the objective of optimizingsurgical options based on hemodynamic optimization. Hemodynamic parameters werecalculated in each surgery from the view point of geometrical bypass-diversity, andthe influences of different bypass geometries on the surgical outcomes were evaluatedto help cardiovascular surgical decision.The research contents consist of the following aspects:1. Patient-specific cardiovascular surgery modeling. It mainly consists of two parts.One part is the three-dimensional reconstruction of patient-specific anatomy based onmedical slices, and the other is to develop a virtual cardiovascular modeling tool byusing virtual reality technology, with which to establish the computational models.2. Hemodynamic study of surgeries for single ventricle heart defect. The threestages of the Fontan procedure were studied according to different bypass offsets,angles and diameters based on hemodynamic optimization with the aims of separatingsystemic circulatory and pulmonary circulatory, saving energy, achieving balancedflow to both longs, and avoiding dangerous hemodynamic performances such asvortex, low wall shear stress and so on. 3. Hemodynamic study of surgeries for tetralogy of Fallot. Two common systemicto pulmonary shunts, including modified B-T shunt and central shunt, were studied byanalyzing the hemodynamic performance inside of the bypass graft, the blood flowrate from aorta to both lungs and the flow rate of both pulmonary arteries to help thesurgical decision of systemic to pulmonary shunt.4. Hemodynamic study of surgeries for coronary artery stenosis. The influence ofcompetitive flow caused by different coronary artery stenosis on bypass graft wasevaluated from the view point of hemodynamics. A new coronary artery bypass graftdesign called double-bypass graft design was developed to enhance the long-termpatency of coronary artery and reduce the risk of coronary artery stenosis.This study tried to optimize the geometry of the bypass graft through hemodynamicoptimization and established a cardiovascular planning strategy by coupling medicalimage processing, virtual cardiovascular operation and hemodynamic evaluationtogether. This study has potential value to promote the application of cardiovascularsurgical planning and enhance the scientific level of cardiovascular surgery.