چكيده به لاتين
As a treatment for heart failure (alternative to heart transplant), cardiac assist devices are widely used in clinical procedures. However, the effects of the support methods of cardiac assist devices on the biomechanical levels of the aortic valve are still completely unknown. Therefore, the current study investigated such effects that these results can create a relatively clear perspective for the designers of ventricular assist devices. An example of a heart assist device that is indirectly connected to the blood, which through the balloons placed on the ascending aorta by compressing and applying tension to the aorta wall, causes pressure to be applied to the blood, and as a result, the blood with pressure and It flows faster in the aorta and is transferred to other organs. As a result of the increase in blood velocity caused by the pressure applied to the aorta due to cardiac assist equipment, it directly affects the aortic surfaces of the leaflets at the end of the systolic phase and the length of the diastolic phase. We have investigated the effects of back pressure on the back of the inserted leaflets from a fluid-structure interaction (FSI) method, which uses the optional Lagrangian-Eulerian (ALE) method. The results show that the support method of cardiac assist devices can significantly affect the biomechanical levels of the aortic valve and the blood flow pattern in the ascending aorta. The results showed that the return blood pressure behind the aortic leaflets up to 20000 pascals, equivalent to the valve force of 1.8 N/mm2, can result in the lowest tension and the lowest radial displacement of the leaflets up to 0.3 mm for the aortic leaflets, which is very suitable in this case. And it does not cause serious damage to the aortic leaflets. The return blood pressure behind the leaflets is up to 40,000 pascals, equivalent to the valvular force equal to 3.4 N/mm2, a stress equivalent to 58,000 pascals enters the aortic leaflets, and the deformation and radial displacement of the leaflets is between 0.5 and 2 mm, which is partly due to the deformation. and slight displacement of the aortic leaflets, but it is possible that during the long period of using the ventricular assist device over time, the aortic valve is damaged and the person suffers from valvular diseases. Therefore, according to the results of this study, the best working area of the back pressure of the blood behind the aortic leaflets is between 20,000 and 40,000 pascals, equivalent to 1.8 to 3.4 newtons/mm2, which causes the least damage to the structural form and function of the valve. But the return blood force more than this value and a value of about 4.2 newtons/mm2 can have a serious effect on the aortic valve.
