Geometrical Multi-scale And PIV Experimental Study Onhemodynamics Of Glenn Surgery

Glenn procedure is the second step of Fontan procedure treating congenital heart disease of single ventricle syndrome. Glenn surgery is the procedure to anastomose superior vena cava and pulmonary artery with end to side anastomosis, and the venous blood from superior vena cava flow directly into the left and right pulmonary artery into the lungs to exchange oxygen, without mixing the arterial blood from pulmonary vein, thereby reducing the symptoms of cyanosis.Hemodynamic factor is an important factor that affects the recovery after surgery of cardiovascular disease. Single ventricle patients often accompany with complications such as vascular dysplasia, of which the most common is pulmonary stenosis. Different pulmonary artery stenosis can cause different flow conditions, and effect physiological needs of patients such as left and right pulmonary flow and energy loss, also cause adverse hemodynamic factors in the perspective of hemodynamic, which may impact on the success rate and long-term effectiveness of surgery.Currently, clinical surgery is mainly based on surgical experience and two-dimensional medical images,lacking of systematic planning theory. The method of geometric multi-scale can be used to achieve surgical planning,which can obtain hemodynamic parameters and provide certain clinical reference.The study includes:1、 rebuilding four three-dimensional models of patients with single ventricle after Glenn surgery with different pulmonary stenosis rate for the comparison of different effects on hemodynamics because of different pulmonary stenosis rate;2、 establishing a lumped parameters model of single ventricle patients which can reflect human circulatory system,verifying the correctness of the models through comparing with the clinical information;3、 coupling the 3-dimensional model and lumped parameters model and doing hemodynamics simulation,then comparing the effect of different pulmonary stenosis rate on the development of patients after Glenn surgery;4、 producing a set of transparent models for PIV experiments,including silicone andglass,doing several groups of steady-state experiments on the basis of numerical simulation.The results show that:Different development of patients’ vessel has important impact on the recovery and development of the single ventricle patients after Glenn surgery. For single ventricle patients accompanied with unilateral pulmonary stenosis, the results revealed that gradually decreasing left pulmonary artery shunt rate and increased the energy loss with the degree of unilateral pulmonary artery stenosis, and when the stenosis is 75% or higher than 75%, a sharp decline appeared in the left pulmonary artery shunt, and the energy loss is far higher and larger high OSI area existed than that in other models. These hemodynamic parameters showed that when the degree of left pulmonary stenosis was 75% or higher than 75%, the stenosis has adverse effect to the vessel on the same prescription of Glenn surgery.In this study, single ventricle patients at different levels of unilateral pulmonary artery stenosis were conducted virtual Glenn surgery. The method of geometric multi-scale can provide accurate boundary conditions to 3D models,with which the hemodynamic impacts of different degree of stenosis on patients after Glenn procedure was studied,and Particle Image Velocimetry(PIV) technique was used in this study to verify numerical simulation results.