Biocompatible materials of pulsatile and rotary blood pumps: A brief review

The biomedical materials that have been used in the structure of heart pumps are classified as biocompatible, and these can be metals, polymers, ceramics, and composites. Their positions in the pump vary according to the part’s function. Whereas various materials have different properties, all biomaterials chosen for cardiovascular applications should have excellent blood biocompatibility to reduce the likelihood of hemolysis and thrombosis. There are two major categories of the heart pumps; pulsatile and rotary blood pumps (axial and centrifugal) and the features of some of these materials allow them to be used in both. Rotary and pulsatile blood pump devices have to be fabricated from materials that do not result in adverse biological responses. The purpose of this review is to study the available biocompatible materials for the pulsatile and rotary blood pumps as clinically-approved materials and prototype heart pump materials. The current state of bio-compatible materials of rotary and pulsatile blood pump construction is presented. Some recent applications of surface amendment technology on the materials for heart assist devices were also reviewed for better understanding. The limitations of heart assist devices, and the future direction of artificial heart elements have been considered. This review will be considered as a comprehensive reference to rapidly understanding the necessary research in the field of biocompatible materials of pulsatile and blood rotary pumps.

Automation of the Harvard Apparatus Pulsatile Blood Pump

Producing accurate physiological circulatory conditions in vitro is integral to the evaluation of cardiac assist technologies. The ability to simulate cardiac function, normal or pathological, is dependent on the capabilities of the pump deployed for this purpose. Presented is a reference standard for this in vitro analysis, with automation features targeted for robust bench-top testing. Cardiac performance is typically described in terms of stroke volume, heart rate, and percent systole. Respectively, these three settings prescribe the volume of fluid ejected, the rate of pumping, and the percentage of the pumping cycle spent in ejection. A pump that provides settings for each of these parameters and precise repeatability allows for accurate construction of simulation conditions. These capabilities are present in the commercially available Harvard Apparatus 1423 pulsatile blood pump. Modifications have been made to this particular model that allow for the automation of its function and real-time performance determination. Discussed in this publication is the design and performance of a modified 1423 pump that employs universal serial bus (USB) communication in the control of its stroke volume, heart rate, and percent systole. The percent systole is denoted as the phase ratio on the hardware. Utilization of an embedded microcontroller (MCU) allows for not only the digital communication via a computer terminal, but process control of the subsystems maintaining each parameter. Care was taken to preserve the mechanical design employed by Harvard Apparatus; the modifications were not invasive to the mechanical driveline of the pump. Electromechanical design characterization was performed in Simulink® using the following Simscape™ block sets: Simscape™ Foundation Library, SimElectronics®, and SimMechanics™. This provided an accurate model of the systems during the design process, which assisted in the deployment of the process controllers with minimal prototype construction. Communication with the MCU is achieved with American Standard Code for Information Interchange (ASCII) commands delivered through a LabVIEW VI interface. Continuous readbacks on fill/ejection rate, pump rate (HR), percent systole (PS), and stroke volume (SV) are possible with these modifications. The deployed upgrade allows for complete automation of the Harvard Apparatus 1423 pulsatile blood pump, with the capability to run sequences of conditions without the need for manual intervention.