Predictors of resuscitation in a swine model of ischemic and nonischemic ventricular fibrillation cardiac arrest: Superiority of amplitude spectral area and slope to predict a return of spontaneous circulation when resuscitation efforts are prolonged*

Utility of the Ventricular Fibrillation Waveform to Predict a Return of Spontaneous Circulation and Distinguish Acute From Post Myocardial Infarction or Normal Swine in Ventricular Fibrillation Cardiac Arrest

“…12 AMSA was calculated as the summed product of frequency and square root of power at that frequency, from 4 to 48 Hz, as computed from a fast Fourier transform. AMSA essentially reflects the product of mean frequency and amplitude.…”

“…Animals in the acute MI and control groups were also used in a recently reported study. 12 Animals in the post MI group were given lidocaine (2 mg/kg) during plug placement to avoid VF during the acute MI. After a 2-week recovery period, the animal was returned to the laboratory and hemodynamic measurements (aortic, right atrial, pulmonary artery, and pulmonary capillary wedge pressure) were made, followed by electric induction of VF with a 100-Hz alternating current delivered from a pacing catheter in the right ventricle.…”

“…11 In a swine study of VF of short duration, the optimal intervention was defibrillation in either an acute MI or normal myocardium. 12 When untreated VF is prolonged beyond 4 minutes and up to about 10 minutes, the myocardium is described as being in the circulatory phase, 11 and in this phase the characteristics of the VF waveform, including parameters based on frequency and amplitude such as amplitude spectral area (AMSA) and slope, have shown good promise as predictors for achieving a return of spontaneous circulation (ROSC) in human and animal studies. [13][14][15][16][17][18][19][20][21] However, it is unclear whether the predictive ability of AMSA and slope to achieve ROSC is affected by the underlying myocardial substrate, such as the presence of an acute MI, a prior MI without acute ischemia, or normal myocardium.…”

Waveform Analysis–Guided Treatment Versus a Standard Shock-First Protocol for the Treatment of Out-of-Hospital Cardiac Arrest Presenting in Ventricular Fibrillation

“…[18][19][20][21] Correlations between VF waveform properties and survival have also been shown. 22,23 For this reason, the utility of waveform analysis for the guided management of VF has been suggested. [24][25][26] Conceptually, using waveform analysis to identify those patients in the electrical phase would allow them to receive immediate defibrillation, whereas those patients in the circulatory phase could selectively receive delayed defibrillation.…”

Defibrillation Shock Amplitude, Location and Timing

“…Therefore, additional studies are needed to evaluate the importance of timing in prolonged episodes of ventricular fibrillation termination. Several studies evaluated the ventricular fibrillation electrogram amplitude spectral area (AMSA) and slope not to predict merely the defibrillation efficacy, but to predict the result of resuscitation (Indik et al, 2010;Povoas & Bisera 2000). As previously mentioned (Section 3), the high waveform amplitude may suggest short duration ventricular fibrillation and not necessarily timing.…”