Activity-sensing permanent internal pacemaker dysfunction during helicopter aeromedical transport

This study was designed to establish the frequency, magnitude, and possible etiologies of the dysfunction of activity-sensing internal pacemakers during helicopter aeromedical transport.

Two models of Medtronic Activitrax pacemakers were attached externally to healthy adult volunteers. Each volunteer then was loaded into the helicopter and subjected to a flight sequence. Pacemaker firing rates throughout this sequence were recorded.

On separate days, Aerospatiale Dauphin and Twinstar helicopters completed a total of 23 flights.

Four healthy adult volunteers, two men and two women, participated.

These included intra- and inter-flight threshold re-programming and external magnet application.

The average preflight pacemaker rate of 65 beats per minute increased to an average in-flight rate of 105 beats per minute, which resolved to preflight rates on shutdown. This pattern was consistently extinguished with external magnet application.

The effect of rotor motion and flight vibration on the rate-response of the Activitrax pacemaker is both predictable and easily preventable. Possible guidelines for the safe transport of these patients, using pacemaker reprogramming or external magnet application, are examined.