PubMed · 7371144
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J A Werner. 1980. Ventricular defibrillation.. https://doi.org/10.1161/01.cir.61.6.1270
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OBJECTIVE: The purpose of this study was to assess from the ventricular fibrillation ECG signal whether certain amplitude parameters, or frequency parameters derived using fast Fourier transform analysis, are predictive of countershock success (defined as a stable supraventricular rhythm following countershock). DESIGN: Retrospective, descriptive study. SETTING: Emergency medical service at a university hospital. PATIENTS: Twenty-six patients with out-of-hospital cardiac arrest, whose initial ECG rhythm was identified as ventricular fibrillation. METHODS AND RESULTS: In all patients, advanced cardiac life support was performed in the out-of-hospital setting and a semiautomatic defibrillator was used for countershock therapy and simultaneous on-line ECG recording. For each patient, ECG data were stored in modules in digitized form over a period of 20 min and analyzed retrospectively. Using fast Fourier transform analysis of the ventricular fibrillation ECG signal in the frequency range of 0.3 to 30 Hz (mean +/- SD), median frequency, dominant frequency, edge frequency, and amplitude were as follows: 5.17 +/- 1.05 Hz, 4.56 +/- 0.99 Hz, 10.74 +/- 3.46 Hz, and 1.33 +/- 0.44 mV before successful countershock (n = 20); and 4.21 +/- 1.17 Hz (p = 0.0034), 3.31 +/- 1.57 Hz (p = 0.0004), 9.46 +/- 2.93 Hz (p = 0.5390), and 1.15 +/- 0.69 mV (p = 0.0134) before unsuccessful countershock (n = 134). Using software filters to completely eliminate interference due to manual cardiopulmonary resuscitation from the ventricular fibrillation power spectrum, only amplitude remained statistically different (p < or = 0.03) in predicting countershock success. CONCLUSIONS: We conclude that in patients, median frequency, dominant frequency, and amplitude are predictive of countershock success in humans.
This study examines in a prospective, multicenter trial the feasibility and advantage of current-based, transthoracic defibrillation. Current-based, damped, sinusoidal waveform shocks of 18, 25, 30, 35, or 40 amperes (A) were administered beginning with 25 A for polymorphic ventricular tachycardia (VT) and ventricular fibrillation (VF) or 18 A for monomorphic VT; success rates were compared with those of energy-based shocks beginning at 200 J for VF/polymorphic VT and 100 J for VT. The current-based shocks were delivered from custom-modified defibrillators that determined impedance in advance of any shock using a "test-pulse" technique; the capacitor then charged to the exact energy necessary to deliver the operator-selected current against the impedance determined by the defibrillator. Three hundred sixty-two patients received > 1 shock for VF, polymorphic VT, or monomorphic VT: 569 current- based shocks and 420 energy-based shocks. Current-based shocks of 35/40 A achieved success rates of up to 74% for VF/polymorphic VT; 30 A shocks terminated 88% of monomorphic VT episodes. Energy-based shocks of 300 J terminated 72% of VF/polymorphic VT; 200-J shocks terminated 89% of monomorphic VT. We could not demonstrate a significant increase in the success rate of current-based shocks over energy-based shocks for patients with high transthoracic impedance; this may be due to inadequate sample size. Thus, current-based defibrillation is clinically feasible and effective. A larger study will be needed to test whether current-based defibrillation is superior to energy-based defibrillation.