Encircling overlapping multipulse shock waveforms for transthoracic defibrillation

Objectives. This study was performed to determine the efficacy of new encircling overlapping multipulse, multipathway waveforms for transthoracic defibrillation.

Background. Alternative waveforms for transthoracic defibrillation may improve shock success.

Methods. First, we determined the shock success achieved by three different waveforms at varying energies (18–150 J) in 21 mongrel dogs after short-duration ventricular fibrillation. The waveforms tested included the traditional damped sinusoidal waveform, a single pathway biphasic waveform, and a new encircling overlapping multipulse waveform delivered from six electrode pads oriented circumferentially. Second, in 11 swine we compared the efficacy of encircling overlapping multipulse shocks given from six electrode pads and three capacitors versus encircling overlapping shocks given from a device utilizing three electrodes and one capacitor.

Results. In the first experiment, the encircling overlapping waveform performed significantly better than biphasic and damped sinusoidal waveforms at lower energies. The shock success rate of the overlapping waveform (six pads) ranged from 67 ± 4% (at 18–49 J energy) to 99 ± 3% at ≥150 J; at comparable energies biphasic waveform shock success ranged from 26 ± 5% (p < 0.01 vs. encircling overlapping waveforms) to 99 ± 5% (p = NS). Damped sinusoidal waveform shock success ranged from 4 ± 1% (p < 0.01 vs. encircling overlapping waveform) to 73 ± 9% (p = NS). In the second experiment the three electrode pads, one capacitor encircling waveform achieved shock success rates comparable with the six-pad, three-capacitor waveform; at 18–49 J, success rates were 45 ± 15% versus 57 ± 12%, respectively (p = NS). At 100 J, success rates for both were 100%.

Conclusions. We conclude that encircling overlapping multipulse multipathway waveforms facilitate transthoracic defibrillation at low energies. These waveforms can be generated from a device that requires only three electrodes and one capacitor.