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Comparison of fixed tilt and tuned defibrillation waveforms: the PROMISE study
Michael R Gold1, Jesus Val-Mejias, Frank Cuoco
1Medical University of South Carolina, Charleston, South Carolina 29425-5920, USA. goldmr@musc.edu
Journal of Cardiovascular Electrophysiology
|December 6, 2012
Summary
This study found that tuned and fixed-tilt biphasic waveforms used in implantable defibrillators (ICDs) have similar defibrillation efficacy. The tuned waveform, adjusted for shock impedance, did not show superiority over the standard fixed-tilt waveform in this patient group.
Area of Science:
- Cardiovascular Medicine
- Biomedical Engineering
- Electrophysiology
Background:
- Modern defibrillation systems rely on biphasic shock waveforms.
- Implantable defibrillators (ICDs) typically use fixed tilt waveforms, but tuned waveforms may offer theoretical advantages.
Purpose of the Study:
- To compare the defibrillation efficacy of fixed tilt and tuned biphasic waveforms in ICDs.
- To evaluate if a tuned waveform, based on shock impedance, is superior to a fixed 50/50% tilt waveform.
Main Methods:
- A prospective, within-patient, randomized study (PROMISE) was conducted.
- Defibrillation thresholds (DFTs) were compared between a tuned waveform (3.5 ms membrane time constant) and a 50/50% tilt waveform.
- Testing involved left pectoral implants with active can and single coil configurations in 52 patients.
Main Results:
- The tuned waveform showed similar delivered energy, stored energy, peak current, and delivered voltage at the DFT compared to the 50/50% tilt waveform.
- No statistically significant differences were observed in key energy and current parameters between the two waveform types.
Conclusions:
- The defibrillation thresholds for tuned (3.5 ms time constant) and 50/50% tilt waveforms are comparable.
- These findings suggest that for single coil, left pectoral active can ICDs, the standard fixed-tilt waveform is as effective as the tuned waveform.
