Related Experiment Videos
Biphasic transthoracic defibrillation causes fewer ECG ST-segment changes after shock
R K Reddy1, M J Gleva, B E Gliner
1Department of Medicine, University of Washington, Seattle 98195-6422, USA.
Annals of Emergency Medicine
|August 1, 1997
Summary
Biphasic transthoracic defibrillation causes less ST-segment elevation, indicating reduced myocardial dysfunction, compared to monophasic waveforms. This study validates biphasic waveforms for safer defibrillation in patients.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Devices
Background:
- Electrocardiogram (ECG) abnormalities, particularly ST-segment changes, are common after transthoracic defibrillation.
- These changes may signify ischemic or shock-induced cardiac dysfunction following resuscitation.
- Biphasic waveforms have shown promise in reducing cardiac dysfunction in laboratory settings, but human validation was needed.
Purpose of the Study:
- To prospectively evaluate the effect of biphasic versus monophasic transthoracic defibrillation waveforms on ECG ST segments in human subjects.
- To compare the incidence and severity of post-shock ST-segment changes between biphasic and monophasic waveforms.
- To assess if biphasic waveforms reduce evidence of myocardial dysfunction without compromising defibrillation efficacy.
Main Methods:
- A prospective, blinded study involving 30 patients undergoing cardioverter-defibrillator implantation.
- Comparison of two low-energy biphasic shocks (115 J, 130 J) against a standard 200 J monophasic damped-sine wave shock.
- Analysis of digitized 15-second ECG signals, focusing on ST-segment deflection 80 msec after the J point, comparing post-shock values to baseline.
Main Results:
- Significantly greater ST-segment elevation was observed with the 200 J monophasic waveform (2.09 +/- 0.37 mm) compared to both biphasic waveforms (-0.02 +/- 0.36 mm for 115 J, 0.21 +/- 0.38 mm for 130 J).
- P-value of <.0001 indicated a statistically significant difference in ST-segment elevation.
- No significant changes in QRS-interval duration, QT interval, or heart rate were noted across any waveform type.
Conclusions:
- Transthoracic defibrillation using biphasic waveforms results in less post-shock ECG evidence of myocardial dysfunction (injury or ischemia).
- Biphasic waveforms offer a potential advantage over standard monophasic damped sine waveforms in minimizing cardiac impact.
- Defibrillation efficacy is maintained with biphasic waveforms, suggesting they are a safer alternative without compromising resuscitation success.