Ventricular Fibrillation Amplitude Research Articles

Amiodarone and ventricular fibrillation amplitude of spectral area in patients with out-of-hospital cardiac arrest. Is there an effect?

Abstract Background The use of antiarrhythmic drug therapy is usually recommended in addition to defibrillation in shockable cardiac arrest. The role of the amplitude spectral area (AMSA) of ventricular fibrillation as a predictor of defibrillation efficacy has been established, but little is known about how amiodarone could affect AMSA values. Purpose The aim of our study was to evaluate whether the administration of amiodarone during resuscitation could affect AMSA and to verify if AMSA preserves its predictive role of shock success in OHCA patients treated with amiodarone. Material All the OHCAs with an attempted resuscitation and at least one shockable rhythm which occurred from January 2015 to December 2020 in the province of Pavia were considered. AMSA values were calculated by retrospectively analyzing the data collected by the Corpuls 3 monitors/defibrillators (Corpuls, Kaufering, Germany) used in the field and by considering a pre-shock interval of 2 seconds. Results Of 4619 OHCAs, 697 underwent attempted CPR with at least one shock delivered. Of these, AMSA was available on 250 patients (male 84%, median age 67 years), for a total of 830 shocks, of which 534 (64%) shocks were in patients receiving amiodarone. The success rate of each single shock was similar in the two groups (amiodarone 42% vs no amiodarone 41%, p=0.68). The AMSA median values were significantly lower in the amiodarone group as compared to the non-amiodarone group when shocks were delivered to patients older than 67 years old [median difference: 1.55 mV Hz (95% CI 0.6–2.5), p=0.0013] or receiving bystander CPR [median difference 0.9 mV Hz (95% CI 0.1–1.8), p=0.03] or after more than 33 minutes from the emergency call to each single shock [median difference: 0.91 mV Hz (95% CI 1.9–0.01), p=0.047]. AMSA value lower than the median (8.3 Hz mV) was associated with a lower probability of shock success (19% vs 64%, p<0.001). According to a multivariate analysis corrected for age, sex, witnessed status, call to shock time and bystander CPR, the probability of having AMSA lower than the median was independently associated with the administration of amiodarone [OR 1.5 (95% CI 1.1–2.1) p=0.009]. At ROC curves analysis, amongst patients receiving amiodarone, AMSA was confirmed to be a predictor of both shock success and ROSC [AUC 0.755 (95% CI 0.72–0.79), p<0.001 and AUC 0.826 (95% CI 0.79–0.86), p<0.001 respectively], similarly to the general population [AUC 0.778 (95% CI0.75–0.81), p<0.001; AUC 0.817 (95% CI 0.79–0.84), p<0.001]. Conclusions Amiodarone administration is independently associated with lower values of AMSA. This could justify the lack of benefit from amiodarone administration in term of defibrillation success which would be expected by the administration of an antiarrhythmic drug during the resuscitation. Moreover, AMSA maintains its predictive value for shock success and ROSC rate in patients receiving amiodarone as well as in the general population. Funding Acknowledgement Type of funding sources: None.

Ventricular fibrillation amplitude spectral area as a guide to deliver the optimal energy level for defibrillation

Abstract Introduction In case of cardiac arrest due to ventricular fibrillation (VF) or pulseless ventricular tachycardia (pVT), the optimal energy should be the lowest energy effective to achieve defibrillation minimizing the current-induced myocardial damage. Therefore, it would be ideal to minimize the energy level as well as the number of shocks during resuscitation. ECG-based VF waveform analysis features such as amplitude spectral area have been recently introduced as predictors of shock success, but their predictivity for shock success with low energy level is not known. Purpose To assess whether amplitude spectral area (AMSA) of VF is able to predict the efficacy of low energy level defibrillation in out-of-hospital cardiac arrest (OHCA) patients. Methods All the OHCAs with at least one shockable rhythm that occurred from January 2015 to December 2020 were considered. AMSA values were calculated by retrospectively analyzing the data collected by the Corpuls 3 monitors/defibrillators and by using a 2-second-pre-shock ECG interval. Results Among 4619 OHCAs, resuscitation was attempted in 2982 (64%) and at least one shock was delivered in 697 (15%). AMSA values and defibrillation energy were available for 791 shocks, of which 45% received shock at low energy (>150J) and 55% at high energy (>150J). The rate of efficacy between the two groups was similar (44% vs 38%, p=0.102). However, in patients efficaciously treated with shock at low energy, AMSA was higher compared to those treated with shock at high energy [13.2 mV Hz (IQR 10.2–17) vs 10.8 mV Hz (IQR 8–13.8), p<0.001]. Moreover, AMSA values were significantly different when comparing ineffective shock at low energy with effective shock at high energy [6.6 mV Hz (IQR 4.6–10) vs 10.8 mV Hz (IQR 8.1–13.8), p<0.001] and similar when comparing ineffective shock at low and high energy [6.6 mV Hz (IQR 4.6–10) vs 6.3 mV Hz (IQR 4.5–8.7), p=0.21]. By dividing AMSA values into three tertiles, the rate of shock success at low energy was statistically different: [T1 (0.7–6.2 mV Hz) 4.2%; T2 (6.2–10.8 mV Hz) 13%; T3 (10.8–63.2 mV Hz) 42%; Chi-squared p<0.001 and p for trend <0.001]. After correction for age, sex, amiodarone use and call to shock time, AMSA values corresponding to the third and second tertile were associated with higher probability of shock success at low energy compared to the lowest tertile [T3 OR 15 (95% CI 7–30), p<0.001; T2 OR 3 (95% CI 1–7), p=0.002]. Conclusion Ventricular fibrillation amplitude spectral area is a predictor of shock success at a low energy level. This could be useful to optimize both time and dose-energy to patients, yielding the highest chance for successful defibrillation while reducing the number of futile shocks and thus limiting the total current myocardial energy as well as CPR interruptions. Funding Acknowledgement Type of funding sources: None.

Targeted Delivery of Electrical Shocks and Epinephrine, Guided by Ventricular Fibrillation Amplitude Spectral Area, Reduces Electrical and Adrenergic Myocardial Burden, Improving Survival in Swine.

BackgroundWe previously reported that resuscitation delivering electrical shocks guided by real‐time ventricular fibrillation amplitude spectral area (AMSA) enabled return of spontaneous circulation (ROSC) with fewer shocks, resulting in less myocardial dysfunction. We now hypothesized that AMSA could also guide delivery of epinephrine, expecting further outcome improvement consequent to less electrical and adrenergic burdens.Methods and ResultsA swine model of ventricular fibrillation was used to compare after 10 minutes of untreated ventricular fibrillation a guidelines‐driven (n=8) resuscitation protocol, delivering shocks every 2 minutes and epinephrine every 4 minutes, with an AMSA‐driven shocks (n=8) protocol, delivering epinephrine every 4 minutes, and with an AMSA‐driven shocks and epinephrine (ADSE; n=8) protocol. For guidelines‐driven, AMSA‐driven shocks, and ADSE protocols, the time to ROSC (mean±SD) was 569±164, 410±111, and 400±80 seconds (P=0.045); the number of shocks (mean±SD) was 5±2, 3±1, and 3±2 (P=0.024) with ADSE fewer than guidelines‐driven (P=0.03); and the doses of epinephrine (median [interquartile range]) were 2.0 (1.3–3.0), 1.0 (1.0–2.8), and 1.0 (0.3–3.0) (P=0.419). The ROSC rate was similar, yet survival after ROSC favored AMSA‐driven protocols (guidelines‐driven, 3/6; AMSA‐driven shocks, 6/6; and ADSE, 7/7; P=0.019 by log‐rank test). Left ventricular function and survival after ROSC correlated inversely with electrical burden (ie, cumulative unsuccessful shocks, J/kg; P=0.020 and P=0.046) and adrenergic burden (ie, total epinephrine doses, mg/kg; P=0.042 and P=0.002).ConclusionsDespite similar ROSC rates achieved with all 3 protocols, AMSA‐driven shocks and ADSE resulted in less postresuscitation myocardial dysfunction and better survival, attributed to attaining ROSC with less electrical and adrenergic myocardial burdens.

Ventricular fibrillation amplitude analysis and comparison for transvenous ICD and extravascular ICD systems

Abstract Background Transvenous (TV) implantable cardioverter-defibrillator (ICD) and extravascular (EV) ICD have very different electrode configurations (Figure 1). TV ICD has direct contact with the heart via endocardial lead placement with a nominal Tip-Ring sensing vector, whereas EV ICD utilizes a lead placed substernally outside the heart, with S1-S2 sensing vector as the nominal. Different lead and electrode locations result in different electrogram (EGM) signal amplitude and variability. Small ventricular fibrillation (VF) amplitude may lead to undersensed VF. Purpose The purpose is to characterize the VF amplitude from nominal sensing vector for TV ICD and EV ICD. Methods For TV ICD, 435 VF segments from Tip-Ring vector in 80 patients were analyzed. For EV ICD, 72 VF segments from S1-S2 vector in 32 patients were analyzed. For each VF segment, 1-second moving window with 50% overlapping was used to calculate maximum rectified (MR) VF amplitude. We calculated the maximum, minimum, mean, and standard deviation of averaged MR amplitude for all the episodes for each vector. The percentage of episodes with averaged MR amplitude smaller than different amplitude thresholds was also computed for each of the two vectors. Results VF signals from EV ICD had smaller averaged MR amplitude than TV ICD: S1-S2 = 3.05±1.62 mV versus Tip-Ring = 6.98±2.10 mV. EV ICD had 65% of episodes above 2.00 mV vs. 96% for TV ICD. The VF amplitude for EV ICD also had a smaller range than TV ICD: 0.47–8.43 mV versus 0.88–16.00mV. Despite having smaller amplitude, recordings of all VF episodes for both systems met detection criteria with no clinically significant delay. Conclusions Without direct myocardial contact, mean VF EGM amplitude from EV ICD system is approximately 44% of that for the TV ICD system. But with less variability across patients, it is more likely that a single (nominal) sensitivity setting will be effective among the population with EV ICD. Funding Acknowledgement Type of funding sources: Private company. Main funding source(s): Medtronic Figure 1Figure 2

The impact of ventricular fibrillation amplitude on successful cardioversion, resuscitation duration, and survival after out-of-hospital cardiac arrest

The impact of ventricular fibrillation amplitude on successful cardioversion, resuscitation duration, and survival after out-of-hospital cardiac arrest

The impact of ventricular fibrillation amplitude on successful cardioversion, resuscitation duration, and survival after out-of-hospital cardiac arrest

Objective: We sought to examine the incidence of low amplitude ventricular fibrillation and its impact on successful cardioversion, duration of resuscitation, and survival to hospital discharge in patients with out-of-hospital cardiac arrest (OHCA). Design: Retrospective analysis from a statewide registry. Setting: Victoria, Australia. Participants: Consecutive initial ventricular fibrillation arrests with an emergency medical service (EMS)-attempted resuscitation between 1 February 2019 and 30 January 2020. Main outcome measures: Survival to hospital discharge, successful cardioversion, and duration of resuscitation. Results: Of the 471 initial ventricular fibrillation arrests, 429 (91.1%) had sufficient electrocardiogram data for review. The median initial and final ventricular fibrillation amplitude did not differ (0.3 mV; interquartile range [IQR], 0.2-0.5 mV). The final pre-shock amplitude was ≤ 0.1 mV (very fine) and ≤ 0.2 mV (fine) in 22.8% and 37.5% of cases respectively. In a multivariable analysis, only the time between emergency call and first defibrillation was associated with a low initial ventricular fibrillation amplitude ≤ 0.2 mV (adjusted odds ratio [aOR], 1.07; 95% CI, 1.02-1.13; P = 0.004). After adjustment for arrest factors, every 0.1 mV increase in final amplitude was independently associated with survival to hospital discharge (aOR, 1.26; 95% CI, 1.14-1.39; P < 0.001) and initial cardioversion success (aOR, 1.19; 95% CI, 1.07-1.32; P = 0.001). The duration of resuscitation also increased by 1.7 minutes (95% CI, 1.03-2.36; P < 0.001) for every 0.1 mV increase in final amplitude. Conclusion: More than one-third of initial ventricular fibrillation OHCA cases were low in amplitude. Comparative international data are needed to better understand how low amplitude ventricular fibrillation rhythms confound the measurement of OHCA interventions and international benchmarks for survival outcomes.

End-tidal carbon dioxide (ETCO2) and ventricular fibrillation amplitude spectral area (AMSA) for shock outcome prediction in out-of-hospital cardiac arrest. Are they two sides of the same coin?

AimVentricular fibrillation amplitude spectral area (AMSA) and end-tidal carbon dioxide (ETCO2) are predictors of shock success, understood as restoration of an organized rhythm, and return of spontaneous circulation (ROSC). However, little is known about their combined use. We aimed to assess the prediction accuracy when combined, and to clarify if they are correlated in out of hospital cardiac arrest' victims. Materials and MethodsRecords acquired by external defibrillators in out-of-hospital cardiac arrest patients of the Lombardia Cardiac Arrest registry were processed. The 1-min pre-shock ETCO2 median value (METCO2) was computed from the capnogram and AMSA (2–48 mV.Hz range) computed applying the Fast Fourier Transform to a 2-second pre-shock filtered ECG interval (0.5−30 Hz). Support Vector Machine (SVM) predictive models based on METCO2, AMSA and their combination were fit; results were given as the area under the curve (AUC) of the receiver operating characteristic (ROC) curves. ResultsWe considered 112 patients with 391 shocks delivered. METCO2 and AMSA were predictors of shock success [AUC (IQR) of the ROC curve: 0.59 (0.56−0.62); 0.68 (0.65−0.72), respectively] and of ROSC [0.56 (0.53−0.59); 0.74 (0.71−0.78),]. Their combination in a SVM model increased the accuracy for predicting shock success [AUC (IQR) of the ROC curve: 0.71 (0.68−0.75)] and ROSC [0.77 (0.73−0.8)]. AMSA and METCO2 were significantly correlated only in patients who achieved ROSC (rho = 0.33 p = 0.03). ConclusionsAMSA and ETCO2 predict shock success and ROSC after every shock, and their predictive power increases if combined. Notably, they were correlated only in patients who achieved ROSC.

First-in-Human Chronic Implant Experience of the Substernal Extravascular Implantable Cardioverter-Defibrillator.

The aim of this study was to evaluate the safety and performance of an extravascular (EV) implantable cardioverter-defibrillator (ICD). Limitations of existing transvenous and subcutaneous ICD systems include lead reliability and morbidity issues associated with ICD lead implantation in the vasculature or lack of pacing therapies (e.g., antitachycardia pacing) in subcutaneous systems. The EV defibrillator uses a novel substernal lead placement to address these limitations. This was a prospective, nonrandomized, chronic pilot study conducted at 4 centers in Australia and New Zealand. Participants were 21 patients referred for ICD implantation. Patients received EV ICD systems. Data collection included major systemic and procedural adverse events, defibrillation testing at implantation, and sensing and pacing thresholds. Among 20 patients who underwent successful implantation, the median defibrillation threshold was 15 J, and 90% passed defibrillation testing with a≥10-J safety margin. Mean R-wave amplitude was 3.4 ± 2.0mV, mean ventricular fibrillation amplitude was 2.8 ± 1.7mV, and pacing was successful in 95% at≤10 V. There were no intraprocedural complications. Two patients have undergone elective chronic system removal since hospital discharge. In the 15 patients presently implanted, the systems are stable in long-term follow-up. This first-in-human evaluation of an EV ICD demonstrated the feasibility of substernal lead placement, defibrillation, and pacing with a chronically implanted system. There were no acute major complications, and pacing, defibrillation, and sensing performance at implantation were successful in most patients. (Extravascular ICD Pilot Study [EV ICD]; NCT03608670).

Abstract 257: Ventricular Fibrillation Amplitude Spectral Area to Assess the Myocardial Effect of Hemodynamic and Metabolic Interventions During Cardiac Resuscitation in a Rat Model

Introduction: The amplitude spectral area (AMSA) of ventricular fibrillation (VF) has been shown to track the myocardial energy state and to predict the effect of defibrillation. We measured AMSA in a rat model of VF and assessed the effects of α-methylnorepinephrine (α-MNE) - a selective peripheral α 2 -adrenoreceptor agonist - given to increase the coronary perfusion pressure without myocardial β 1 -adrenoceptor stimulation and the effects of zoniporide (ZNP) - an inhibitor of the sodium-hydrogen exchanger isoform-1 - given to protect mitochondrial bioenergetic function from reperfusion injury. Methods: VF was electrically induced in 48 rats and left untreated for 8 minutes. Chest compression was then started and defibrillation attempted 8 minutes later. Rats were randomized to receive a 3-mg/kg bolus of ZNP or 0.9% NaCl control (Ctr) before starting chest compression and a 100-μg/kg bolus of α-MNE or 0.9% NaCl control (Ctr) at 2 minutes of chest compression yielding four groups of 12 rats each; ZNP/α-MNE, ZNP/Ctr, Ctr/α-MNE, and Ctr/Ctr. Results: AMSA (mV·Hz; mean±SEM) was 34.9±1.5 at minute one after induction of VF and decreased to 2.6±0.2 at minute eight. With chest compression, AMSA gradually increased attaining different levels among groups (p&lt;0.001). At minute seven of chest compression, AMSA was the highest with ZNP/α-MNE (29.9±2.5; p=0.012 vs Ctr/α-MNE and p&lt;0.001 vs Ctr/Ctr) followed by ZNP/Ctr (24.1±2.5; p=0.016 vs Ctr/Ctr), Ctr/α-MNE (18.9±2.3), and Ctr/Ctr (12.9±2.6). Survival at 240 minutes differed among groups (p=0.007) with the highest survival with ZNP/α-MNE. Analysis of the independent effects of the interventions revealed that AMSA at minute seven was significantly higher with ZNP (27.2±2.6 vs 16.2±1.6; p&lt;0.001) but not with α-MNE (22.9±2.1 vs 18.6±2.8; p=1.000). Survival was significantly higher with ZNP (18/24 vs 7/24; p=0.004) but not with α-MNE (12/24 vs 13/24; p=1.000). Conclusions: AMSA was the highest when ZNP was combined with α-MNE; a combination that also resulted in the highest 240-minute survival. This effect was primarily linked to ZNP without excluding a positive interaction with α-MNE. Accordingly, AMSA may also serve to assess the myocardial effects of metabolic interventions during cardiac resuscitation.

Ventricular fibrillation amplitude spectral area and end-tidal carbon dioxide for shock success and ROSC prediction. Two sides of the same coin?

Purpose: Ventricular fibrillation amplitude spectral area (AMSA) and end-tidal carbon dioxide (ETCO2) have been shown to be predictors of shock success and return of spontaneous circulation (ROSC). However, little is known about their combined use, which is the aim of our study.

Association Between Ventricular Fibrillation Amplitude Immediately Prior to Defibrillation and Defibrillation Success in Out-of-hospital Cardiac Arrest: Balderston JR, Gertz ZM, Ellenbogen KA, et al. Am Heart. J 2018;201:72-76

Association Between Ventricular Fibrillation Amplitude Immediately Prior to Defibrillation and Defibrillation Success in Out-of-hospital Cardiac Arrest: Balderston JR, Gertz ZM, Ellenbogen KA, et al. Am Heart. J 2018;201:72-76

Fuzzy and Sample Entropies as Predictors of Patient Survival Using Short Ventricular Fibrillation Recordings during out of Hospital Cardiac Arrest.

Optimal defibrillation timing guided by ventricular fibrillation (VF) waveform analysis would contribute to improved survival of out-of-hospital cardiac arrest (OHCA) patients by minimizing myocardial damage caused by futile defibrillation shocks and minimizing interruptions to cardiopulmonary resuscitation. Recently, fuzzy entropy (FuzzyEn) tailored to jointly measure VF amplitude and regularity has been shown to be an efficient defibrillation success predictor. In this study, 734 shocks from 296 OHCA patients (50 survivors) were analyzed, and the embedding dimension (m) and matching tolerance (r) for FuzzyEn and sample entropy (SampEn) were adjusted to predict defibrillation success and patient survival. Entropies were significantly larger in successful shocks and in survivors, and when compared to the available methods, FuzzyEn presented the best prediction results, marginally outperforming SampEn. The sensitivity and specificity of FuzzyEn were 83.3% and 76.7% when predicting defibrillation success, and 83.7% and 73.5% for patient survival. Sensitivities and specificities were two points above those of the best available methods, and the prediction accuracy was kept even for VF intervals as short as 2s. These results suggest that FuzzyEn and SampEn may be promising tools for optimizing the defibrillation time and predicting patient survival in OHCA patients presenting VF.

Association between ventricular fibrillation amplitude immediately prior to defibrillation and defibrillation success in out-of-hospital cardiac arrest

BackgroundSeveral characteristics of the ventricular fibrillation (VF) waveform during cardiac arrest are associated with defibrillation success, including peak amplitude in the seconds prior to defibrillation. It is not known if immediate pre-defibrillation amplitude is associated with successful defibrillation, return of spontaneous circulation (ROSC) or survival to hospital discharge (SHD). MethodsWe analyzed automated external defibrillation recordings of 80 patients with out-of-hospital VF cardiac arrest who received 284 defibrillations. We recorded the maximum amplitude during 3-second ECG tracings prior to each defibrillation attempt and the amplitude immediately prior to defibrillation. ResultsBoth the amplitude just prior to defibrillation and the highest amplitude within 3 seconds of the defibrillation were significantly higher in successful vs unsuccessful defibrillations (0.21 vs 0.11 mV, P = <.0001 and 0.51 vs 0.36 mV, P = <.0001). Amplitude immediately prior to defibrillation and maximal amplitude within 3 seconds of defibrillation were also higher in defibrillations with ROSC vs. defibrillations without ROSC (0.23 vs. 0.12 mV, P < .0001; and 0.52 vs. 0.38 mV, P < .0001). In defibrillations that resulted in SHD, immediate pre-defibrillation amplitude and maximum amplitude were also significantly larger (0.20 vs. 0.11 mV, P < .0001; and 0.52 vs. 0.35 mV, P < .0001). Binary logistic regression including both measures showed that only immediate pre-defibrillation amplitude remained significantly associated with ROSC while maximal amplitude did not (P = .006 and P = .135). ConclusionsAmplitude of the VF waveform at the moment of defibrillation has a strong association with successful defibrillation, ROSC, and SHD.

Real-Time Ventricular Fibrillation Amplitude-Spectral Area Analysis to Guide Timing of Shock Delivery Improves Defibrillation Efficacy During Cardiopulmonary Resuscitation in Swine.

BackgroundThe ventricular fibrillation amplitude spectral area (AMSA) predicts whether an electrical shock could terminate ventricular fibrillation and prompt return of spontaneous circulation. We hypothesized that AMSA can guide more precise timing for effective shock delivery during cardiopulmonary resuscitation.Methods and ResultsThree shock delivery protocols were compared in 12 pigs each after electrically induced ventricular fibrillation, with the duration of untreated ventricular fibrillation evenly stratified into 6, 9, and 12 minutes: AMSA‐Driven (AD), guided by an AMSA algorithm; Guidelines‐Driven (GD), according to cardiopulmonary resuscitation guidelines; and Guidelines‐Driven/AMSA‐Enabled (GDAE), as per GD but allowing earlier shocks upon exceeding an AMSA threshold. Shocks delivered using the AD, GD, and GDAE protocols were 21, 40, and 62, with GDAE delivering only 2 AMSA‐enabled shocks. The corresponding 240‐minute survival was 8/12, 6/12, and 2/12 (log‐rank test, P=0.035) with AD exceeding GDAE (P=0.026). The time to first shock (seconds) was (median [Q1–Q3]) 272 (161–356), 124 (124–125), and 125 (124–125) (P<0.001) with AD exceeding GD and GDAE (P<0.05); the average coronary perfusion pressure before first shock (mm Hg) was 16 (9–30), 10 (6–12), and 3 (−1 to 9) (P=0.002) with AD exceeding GDAE (P<0.05); and AMSA preceding the first shock (mV·Hz, mean±SD) was 13.3±2.2, 9.0±1.6, and 8.6±2.0 (P<0.001) with AD exceeding GD and GDAE (P<0.001). The AD protocol delivered fewer unsuccessful shocks (ie, less shock burden) yielding less postresuscitation myocardial dysfunction and higher 240‐minute survival.ConclusionsThe AD protocol improved the time precision for shock delivery, resulting in less shock burden and less postresuscitation myocardial dysfunction, potentially improving survival compared with time‐fixed, guidelines‐driven, shock delivery protocols.

Application of Entropy-Based Features to Predict Defibrillation Outcome in Cardiac Arrest

Prediction of defibrillation success is of vital importance to guide therapy and improve the survival of patients suffering out-of-hospital cardiac arrest (OHCA). Currently, the most efficient methods to predict shock success are based on the analysis of the electrocardiogram (ECG) during ventricular fibrillation (VF), and recent studies suggest the efficacy of waveform indices that characterize the underlying non-linear dynamics of VF. In this study we introduce, adapt and fully characterize six entropy indices for VF shock outcome prediction, based on the classical definitions of entropy to measure the regularity and predictability of a time series. Data from 163 OHCA patients comprising 419 shocks (107 successful) were used, and the performance of the entropy indices was characterized in terms of embedding dimension (m) and matching tolerance (r). Six classical predictors were also assessed as baseline prediction values. The best prediction results were obtained for fuzzy entropy (FuzzEn) with m = 3 and an amplitude-dependent tolerance of r = 80 μ V . This resulted in a balanced sensitivity/specificity of 80.4%/76.9%, which improved by over five points the results obtained for the best classical predictor. These results suggest that a FuzzEn approach for a joint quantification of VF amplitude and its non-linear dynamics may be a promising tool to optimize OHCA treatment.

Safety threshold of R-wave amplitudes in patients with implantable cardioverter defibrillator

ObjectiveA safety threshold for baseline rhythm R-wave amplitudes during follow-up of implantable cardioverter defibrillators (ICD) has not been established. We aimed to analyse the amplitude distribution and undersensing rate during...

Effect of Shen-Fu Injection Pretreatment to Myocardial Metabolism During Untreated Ventricular Fibrillation in a Porcine Model.

Background:Shen-Fu injection (SFI) can attenuate ischemia-reperfusion injury, protect cardiac function, and improve microcirculation during cardiopulmonary resuscitation. We hypothesized that SFI may also have an influence on myocardial metabolism during ventricular fibrillation (VF). In this study, we used SFI pretreatment prior to VF to discuss the changes of myocardial metabolism and catecholamine (CA) levels during untreated VF, trying to provide new evidence to the protection of SFI to myocardium.Methods:Twenty-four pigs were divided into three groups: Saline group (SA group), SFI group, and SHAM operation group (SHAM group). Thirty minutes prior to the induction of VF, the SFI group received 0.24 mg/ml SFI through an intravenous injection; the SA group received an equal amount of sodium chloride solution. The interstitial fluid from the left ventricle (LV) wall was collected through the microdialysis tubes during VF. Adenosine diphosphate (ADP), adenosine triphosphate (ATP), and Na+ -K+ -ATPase and Ca2+ -ATPase enzyme activities were measured after untreated VF. Peak-to-trough VF amplitude and median frequency were analyzed for each of these 5-s intervals.Results:The levels of glucose and glutamate were lower after VF in both the SA and SFI groups, compared with baseline, and the levels in the SFI group were higher than those in the SA group. Compared with baseline, the levels of lactate and the lactate/pyruvate ratio increased after VF in both SA and SFI groups, and the levels in the SFI group were lower than those in the SA group. In both the SA and SFI groups, the levels of dopamine, norepinephrine, and epinephrine increased significantly. There were no statistical differences between the two groups. The content of ATP, ADP, and phosphocreatine in the SFI group was higher than those in the SA group. The activity of LV Na+ -K+ -ATPase was significantly higher in the SFI group than in the SA group. Amplitude mean spectrum area (AMSA) was significantly lower in the SA and SFI groups at 8- and 12-min compared with 4-min. The AMSA in the SFI group was higher than that in the SA group at each time point during untreated VF.Conclusions:SFI pretreatment can improve myocardial metabolism and reduce energy exhaustion during VF, and it does not aggravate the excessive secretion of endogenous CAs.

Abstract 15292: Quantitative Waveform Measures Predict Survival From Out-of-hospital Cardiac Arrest Independent of Prior Cardiovascular Disease

Introduction: Quantitative waveform measures (QWM) of ventricular fibrillation (VF) can predict survival from out-of-hospital cardiac arrest (OHCA). However, cardiovascular disease (CVD) can change QWM as well as outcome from OHCA. We assessed the hypothesis that risk factors for and the presence of CVD were associated with changes in VF amplitude spectrum area (AMSA) and survival from OHCA. Methods: Data from ARREST, a registry of all OHCAs in North-Holland, the Netherlands, were used. Medical history was collected from the general practitioner using a questionnaire. AMSA was calculated for the first artifact free VF segment (mean segment duration 4.8 sec, sample frequency 125 Hz) and prior to every shock. Linear regression was used to assess the association between AMSA, risk factors and CVD, adjusting for resuscitation characteristics. Logistic regression was used to associate AMSA, resuscitation characteristics, risk factors and CVD with survival to hospital discharge. Results: We included 693 patients with an OHCA between 2006 and 2010, available medical history and VF on ECG recording with AED (n=163) or manual defibrillator (n=530), receiving a total of 2675, median 3 defibrillation shocks. Time from EMS call to first rhythm recording was median (IQR) 8.8 min (5.7-11.6), and 295 patients survived to hospital discharge (43%). Mean AMSA for the first analyzable segment was 12.7 (±16.0) mV-Hz, significantly lower for cardiomyopathy and obesity, and higher for known familial sudden cardiac death (SCD) (Table 1). Higher AMSA per mV-Hz increase (adjusted for resuscitation characteristics, risk factors and CVD) was significantly associated with higher survival to discharge (OR 1.04; 95% CI 1.02-1.06; P&lt;0.001). Conclusions: Changes in AMSA due to reported CVD and risk factors are of small magnitude. AMSA remains an independent predictor of survival to hospital discharge, even when adjusting for resuscitation characteristics, risk factors and CVD.

Electrocardiographic characteristics of ventricular fibrillation in patients with a wearable cardioverter defibrillator

Introduction: Surface electrocardiographic (ECG) changes in ventricular fibrillation (VF) waveform characteristics at its onset in patients experiencing cardiac arrest have not been quantified. The amplitude spectral area (AMSA) method was developed to analyze surface ECG VF amplitude and frequency characteristics and contains information related to VF rotor stability and myocardial viability. We aimed to characterize changes in AMSA at the onset of VF to gain insight into myocardial dynamics in patients with a wearable cardioverter defibrillator (WCD).

Is hands-on defibrillation safe when using insulating gloves? A clinical trial

Introduction: Surface electrocardiographic (ECG) changes in ventricular fibrillation (VF) waveform characteristics at its onset in patients experiencing cardiac arrest have not been quantified. The amplitude spectral area (AMSA)methodwas developed to analyze surface ECG VF amplitude and frequency characteristics and contains information related to VF rotor stability and myocardial viability. We aimed to characterize changes in AMSA at the onset of VF to gain insight into myocardial dynamics in patients with a wearable cardioverter defibrillator (WCD). Methods: Out of 30 patients randomly identified from a manufacturer-maintained registry, 25 patients (14 Male, 11 Female, Age=62±14 yr) were included. Remaining patients experienced either sustained monomorphic ventricular tachycardia or hadmotion artifact, precludingAMSAanalysis. Using theWCDECG, AMSA was calculated as the summed product of frequency and square root of power at that frequency from 2 to 48Hz with a continuous sliding 2.1 s Tukey window. The median time to shock for the WCD is 45 s. AMSA was calculated every 0.5 s and averaged every 1 s for up to 45 s after VF initiation. Results are presented as mean± standard error. Results: At onset of VF, AMSA was 33.6±3.3mVHz which decreased progressively to 23.4±2.2mVHz (p<0.01) after 45 sec of untreated VF (Fig. 1).