Biomechanical, Structural and Performance Analysis of a Specific Type of Cardiac Assist Device Used in Left Ventricular Failures

Abstract

This article investigates a specific type of cardiac assist device, its functional performance, and its effects on the hemodynamic patterns of blood flow through the aortic network. The aforementioned assist device can be implanted in a given patient suffering from left ventricular failure. Our previous study focused on multi-balloons device. The current cardiac assist device is composed of two semi-cylindrical double-layer balloons surrounding the ascending aorta, thereby increasing the force with which blood will be pumped into the circulatory system with its inflation and deflation mechanism. The inflation and deflation of the balloon take place during the diastolic and systolic phases of the heart, respectively, by pumping and suctioning a specific gas coming from a micropump into or out of the space between the two layers of the balloons. A three-dimensional model of the aortic network assisted by the cardiac device is constructed based on the patient’s individual anatomical and physiological conditions and simulated within two complete cardiac cycles using the fluid–structure interaction analysis. The simulation is performed using the assumptions of linear elastic materials for the balloon and the aorta, and Newtonian and incompressible fluid for the blood. Result shows that the maximum outflow of the descending aorta increases by 20 ml/s and 10 ml/s in the brachiocephalic artery at time 0.4 s (maximum inflation). This increase is equal to 5 ml/s in the carotid and subclavian arteries. During the time period of 0.4–0.5 s (constant applied pressure), the balloon has no considerable movement. The outflow experiences a nearly uniform flow with slight oscillations within this interval in the presence of the assist device. The net energy of the blood flow is decreased if the Young’s modulus of the balloon part of the assist device increases. Furthermore, the stress generated at the outer curvature of the aorta is higher than that of inner curvature in case of using cardiac assist device. This study demonstrates the relevance of the three-dimensional model in clinical practice. Such simulation can provide clinicians and surgeons with relevant information in order to select the most patient-centered and clinically appropriate cardiac assist device addressing the pathological conditions of a specific patient. Furthermore, this study can be a source of comparison with the previous study on multi-balloons device.