Potential hazards of implanted devices for the electrical control of tachyarrhythmias.

Sensing difficulties are more common with antitachycardia devices employing atrial rather than ventricular leads, but the consequences are potentially more disastrous with ventricular leads. The problem may be magnified in that the spurious discharge from poor sensing is likely to be asynchronous. Worsening of arrhythmias during termination attempts cannot be totally avoided, but may be minimized if caution and expertise are applied to selection and testing. A device which can reliably terminate a tachyarrhythmia accelerated by a termination attempt is the safest.