CARD7: Design of a Hybrid Wireless Left Ventricular Assist Device with a New Charging System

Abstract

Drivelines of the current left ventricular assist devices (LVADs) have some problems such as acting as a source of infection and Drivelines of the current left ventricular assist devices (LVADs) have some problems such as acting as a source of infection and limiting the outside activities of patients, thereby reducing the quality of life of patients. Transcutaneous Energy Transfer Systems (TETSs) have been developed to solve these problems but they have other problems such as malposition between coils and burn injury due to sending high-power transmission. In a previous study, we proposed a new concept of wireless LVAD, which consisted of magnetic and electric pumps, to improve the current problems of conventional wireless LVAD. However, implanting two different pumps in the body could occupy more space than a single pump. In addition, two extracorporeal devices on the skin, an external coil for TETS and extracorporeal rotating magnets for the magnetic pump, were possibly confusing to patients. Moreover, the distance limitation between the extracorporeal magnets and intrathoracic pump remained a fundamental problem of the magnetic pump. To solve these problems, we developed a single hybrid pump driven by either magnetic or electric force and charged wirelessly without an external coil. Our new wireless LVAD was a hybrid pump operating in two different modes: magnetic and electric modes. The pump was driven wirelessly by extracorporeal rotating magnets in magnetic mode, whereas it was driven by electricity from an intracorporeal battery in electric mode. Magnetic torque transmission system was introduced to efficiently transmit magnetic torque to the impeller. The intracorporeal battery was charged in magnetic mode making use of electromagnetic coils as a generator, which operated as a motor in electric mode. Our hybrid pump performed a flow rate and a head pressure of approximately 5.0 L/min and 80 mm Hg, respectively, in a bench-top test. The charging rate of the intracorporeal battery in magnetic mode was around 2.5 W, which enabled the hybrid pump to operate in electric mode 3 hours a day. Magnetic torque transmission system shortened the distance between the extracorporeal and intracorporeal magnets and achieved downsizing the magnets. Our hybrid wireless LVAD solved the potential problems of our previous wireless LVAD and demonstrated a new wireless charging system without an external coil. It has the potential to reduce the problems relating to drivelines and to realize high quality of life of patients with LAVD. Our future prospect is to conduct an in vivo test with our device.Figure 1. Prospective configuration of our hybrid LVAD system: (A) intracorporeal components, (B) positional relationship between the hybrid pump and extracorporeal device.Figure 2. (A) Top view of the impeller, (B) Bottom view of the impeller, (C) Pump housing, (D) Hybrid pumpFigure 3. (A) Front view of the test loop, (B) detailed view of the hybrid pump and extracorporeal magnets