Analysis of Intra-Aortic Axial Pump for Heart Assist

There are major challenges for the current Ventricular Assist Devices VADs to be used as a long term implanted device for patients with serious heart failure. Heart failure usually develops because of damage in the heart by a heart attack, or as a result of other conditions such as cardiomyopathy which causes death of 7.3 million people annually according to the World Health Organisation WHO [1]. Avoiding haemolysis or blood cell damage upon implanting the VADs is among the major challenges for designers [2]. The blood damage occurs as a result of the high shear in the blood flow in the device due to its high rotational speed 6000-12000 rpm, particularly when using axial pump [3]. The large surface contact area with the blood is another source that causes the damage [4]. Other challenges include improper morphological adaptation, serious invasive surgery, and large metal load in human body [2]. In addition to the above challenges, the total cost and risk are still high.

This paper introduces a new concept and design of a heart assist device that can be implanted inside the aorta instead of the current devices that are by-passing the heart using parallel conduits. The flow and the performance of the new VAD has been analysed using Computational Fluid Dynamics CFD as a successful tool to evaluate the pump performance [5]. The results showed that by increasing the rotor diameter and reducing the pump length leads to significant reduction in the rotor rotational speed while achieving 40 mmHg head and 5L/min flow rate. The final design configuration to achieve minimum power and maximum efficiency are presented. The Lagrangian approach was employed to evaluate the resident time and consequently, the haemolysis index [6] which is an indication of blood damage. The new concept will lead to lower blood damage and has a simpler surgical operation with shorter healing time and low risk of bleeding or hospital re-readmission of the patient after implanting the device which are among the problems facing the current devices.