[In vitro study of the effects of high frequency electrical current on cardiac pacemakers]

The authors studied the possible consequences of the use of high frequency electrical currents of cardiac pacemaker function. Twenty-five unipolar pacemakers (22 single and 3 double chamber) were tested. They were connected to a pacing catheter, emerged in a saline bath and submitted to a modulated and then unmodulated current of 348 KHz in as many pacing modes as possible for each unit. Three dangerous deprogrammations were observed which could nevertheless be easily corrected. Five pacemakers immediately adopted the reversion mode specified by their manufacturer. The other changes observed only lasted as long as the electric current was applied. The commonest abnormality was a drop in the output voltage proportional to the energy delivered which sometimes led to true inhibition of the pacemaker. Two abnormal rate increases were observed reaching frequencies higher than 250/mn. No particular pacing mode seemed to protect the pacemakers from the effects of high frequency currents.