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Abstracts: ASAIO Cardiac Abstracts


Chiang, Eric J1; Marchessault, Paul1; Siebenhaar, Andre2; Conrad, Jim3

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HeartMate® III is an implantable LVAD designed for permanent use. Electrical Surgical Units (ESUs) emit high-energy radio frequency waves, which may interfere with the proper functionality of electronic devices including the magnetically levitated LVAD. Recent studies were aimed at evaluating and improving the LVAD’s immunity to ESUs typically used in the operating room.


Two LVAD designs were evaluated for immunity – more specifically, the current design, and one modified with a “T-Filter” circuit. An Ellman Surgitron FFPF ESU generating 140Watts at 4MHz was used as a prequalification test case. A 500 Ohm load was used to simulate body resistance. Each LVAD, while operating on a water loop, was evaluated under the conditions where the ESU probe was operating in close proximity to the LVAD, and when the ESU probe was in direct contact with the LVAD metal housing. The indicator used for failure of immunity was the interruption of flow in the water loop.


Both LVAD designs passed ESU proximity testing showing no interruption in pump operation. The current design, however, failed direct contact testing causing the LVAD to go into reset and resulting in a momentary loss of flow. The LVAD with the “T-Filter” passed both proximity and direct contact testing showing no interruption in flow.


The “T-Filter” circuit effectively improved the LVAD’s immunity to interference generated by the Ellman FFPF ESU. Additional immunity pre-qualification tests with other brands of ESUs, AICDs, and pacemakers are planned for the future.

Copyright © 2005 by the American Society for Artificial Internal Organs