ABSTRACT
The use of a pulsatile square wave stimulus for a large series of electroconvulsive treatments under conditions of routine clinical practice is compared to the equivalent experience with a sine wave stimulus. The literature indicates that both waveforms are equally effective convulsants. However, in this series, the induction of a convulsion was found to be much more difficult with the pulsatile square wave such that the rate of failure to convulse was four times that compared to sine wave stimulation. A number of variables that may affect the seizure threshold during ECT were examined. It is concluded that the benefit obtained by reducing the electrical energy transmitted to the patient with the pulsatile stimulus offsets the difficulty encountered in reaching the seizure threshold.
