Rotary blood pumps often require a constant operating voltage. To meet this requirement and to eliminate the need for percutaneous leads, a voltage-regulated transcutaneous energy transfer (TET) system has been developed. Voltage regulation is achieved by using a transcutaneous infrared feedback control loop operating on a 890 nanometer (nm) wavelength. In vitro testing of the system developed has shown that output voltage can be maintained to within 0.2 V of nominal (14.5 V) for delivered powers up to 50 watts (W) and coil separations of between 3 and 10 mm. Power transfer efficiencies were determined to be from 68% to 72% over the tested range of coil separations and output currents from 1.5 to 3.6 amperes (A). This system has demonstrated acceptable performance in regulating output voltage while transferring power inductively without using percutaneous connections. By integrating this type of TET system with an implanted rotary blood pump, the quality of life for the device recipient could be improved.
An intrathoracic pulsatile artificial heart pump has been developed. Transcutaneous energy transfer and biotelemetry systems provide continuous power and remote monitoring and control, with no percutaneous connections required. The electrohydraulic system can be used either as a ventricular assist device or with modifications as a total artificial heart. The device uses a unidirectional axial flow pump coupled with a pressure activated one-way valve to allow hydraulic fluid to passively return t o the volume displacement chamber during diastole. The transcutaneous energy transfer system provides power to the device and recharges the implantable battery ~~_ _ _ _~ ~
A wireless biotelemetry system for the transfer of digital data through intact skin and tissue has been developed to provide a safe and noninvasive means of communication between implanted medical devices and the outside of the body. The system utilizes 2 miniature infrared transmitter/receiver modules. Data are transmitted through intact skin and subcutaneous tissue on an 890 nm infrared carrier signal. The system has been evaluated in human cadavers and during in vivo implantation of artificial hearts and ventricular assist devices for durations of up to 96 h. Acceptable data transfer (error rate < 10(-5)) through a typical tissue thickness of 5-25 mm has been demonstrated. The ability to monitor and control a device from a remote site using public communication systems such as telephone lines and asynchronous transfer mode (ATM) systems has also been demonstrated. Design optimization is currently ongoing in preparation for clinical utilization with artificial heart systems and other implantable devices (such as rotary blood pumps).
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