A diathermy suppression filter for external pacemakers

Some patients undergoing cardiothoracic surgery require cardiac pacing. Surgical diathermy interferes with the operation of external pacemakers, and can cause a loss of cardiac output. The addition of a simple two-stage LC filter to the front end of the pacemaker enables cardiac output to be maintained during the use of surgical diathermy. (Although this article refers specifically to the Devices E4160 series pacemakers, the filter can, in principle, be used with any external pacemaker.