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Pope MTB, Paisey JR, Roberts PR. Defibrillation Threshold Testing for Right-sided Device Implants: A Review to Inform Shared Decision-making, in Association with the British Heart Rhythm Society. Arrhythm Electrophysiol Rev 2023; 12:e10. [PMID: 37427305 PMCID: PMC10326664 DOI: 10.15420/aer.2022.38] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 12/27/2022] [Indexed: 07/11/2023] Open
Abstract
Prevention of sudden death using ICDs requires the reliable delivery of a high-energy shock to successfully terminate VF. Until more recently, the device implant procedure included conducting defibrillation threshold (DFT) testing involving VF induction and shock delivery to ensure efficacy. Large clinical trials, including SIMPLE and NORDIC ICD, have subsequently demonstrated that this is unnecessary, with a practice of omitting DFT testing having no impact on subsequent clinical outcomes. However, these studies specifically excluded patients requiring devices implanted on the right side, in whom the shock vector is significantly different and smaller studies suggest a higher DFT. In this review, the data regarding the use of DFT testing, focusing on right-sided implants, and the results of a survey of current UK practice are presented. In addition, a strategy of shared decision-making when it comes to deciding on the use of DFT testing during right-sided ICD implant procedures is proposed.
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Affiliation(s)
- Michael TB Pope
- Department of Cardiology, Royal Bournemouth Hospital, Bournemouth, UK
| | - John R Paisey
- Department of Cardiology, University Hospitals Southampton NHS Foundation Trust, Southampton, UK
| | - Paul R Roberts
- Department of Cardiology, University Hospitals Southampton NHS Foundation Trust, Southampton, UK
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2
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Tooley M. Electrical safety, defibrillation and diathermy. BJA Educ 2023; 23:84-91. [PMID: 36844445 PMCID: PMC9947971 DOI: 10.1016/j.bjae.2022.11.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 10/26/2022] [Accepted: 11/21/2022] [Indexed: 01/06/2023] Open
Affiliation(s)
- M.A. Tooley
- University of Bath, Bath, UK
- Royal United Hospitals, Bath, UK
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3
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Gleva MJ, Sullivan J, Crawford TC, Walcott G, Birgersdotter-Green U, Branch KR, Doshi RN, Kivilaid K, Brennan K, Rowbotham RK, Gustavson LM, Poole JE. Defibrillation effectiveness and safety of the shock waveform used in a contemporary wearable cardioverter defibrillator: Results from animal and human studies. PLoS One 2023; 18:e0281340. [PMID: 36917566 PMCID: PMC10013906 DOI: 10.1371/journal.pone.0281340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 01/17/2023] [Indexed: 03/16/2023] Open
Abstract
INTRODUCTION The wearable cardioverter defibrillator (WCD) is used to protect patients at risk for sudden cardiac arrest. We examined defibrillation efficacy and safety of a biphasic truncated exponential waveform designed for use in a contemporary WCD in three animal studies and a human study. METHODS Animal (swine) studies: #1: Efficacy comparison of a 170J BTE waveform (SHOCK A) to a 150J BTE waveform (SHOCK B) that approximates another commercially available waveform. Primary endpoint first shock success rate. #2: Efficacy comparison of the two waveforms at attenuated charge voltages in swine at three prespecified impedances. Primary endpoint first shock success rate. #3: Safety comparison of SHOCK A and SHOCK B in swine. Primary endpoint cardiac biomarker level changes baseline to 6 and 24 hours post-shock. Human Study: Efficacy comparison of SHOCK A to prespecified goal and safety evaluation. Primary endpoint cumulative first and second shock success rate. Safety endpoint adverse events. RESULTS Animal Studies #1: 120 VF episodes in six swine. First shock success rates for SHOCK A and SHOCK B were 100%; SHOCK A non-inferior to SHOCK B (entire 95% CI of rate difference above -10% margin, p < .001). #2: 2,160 VF episodes in thirty-six swine. Attenuated SHOCK A was non-inferior to attenuated SHOCK B at each impedance (entire 95% CI of rate difference above -10% margin, p < .001). #3: Ten swine, five shocked five times each with SHOCK A, five shocked five times each with SHOCK B. No significant difference in troponin I (p = 0.658) or creatine phosphokinase (p = 0.855) changes from baseline between SHOCK A and SHOCK B. Human Study: Thirteen patients, 100% VF conversion rate. Mild skin irritation from adhesive defibrillation pads in three patients. CONCLUSIONS The BTE waveform effectively and safely terminated induced VF in swine and a small sample in humans. TRIAL REGISTRATION Human study clinical trial registration: URL: https://clinicaltrials.gov; Unique identifier: NCT04132466.
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Affiliation(s)
- Marye J. Gleva
- Division of Cardiology, Department of Medicine, Washington University in Saint Louis School of Medicine in Saint Louis, St. Louis, Missouri, United States of America
- * E-mail:
| | - Joseph Sullivan
- Kestra Medical Technologies, Inc., Redmond, Washington, United States of America
| | - Thomas C. Crawford
- Division of Cardiology, Department of Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Greg Walcott
- Division of Cardiovascular Diseases, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | | | - Kelley R. Branch
- Division of Cardiology, Department of Medicine, University of Washington School of Medicine, Seattle, Washington, United States of America
| | | | | | - Kelly Brennan
- Kestra Medical Technologies, Inc., Redmond, Washington, United States of America
| | - Ron K. Rowbotham
- Kestra Medical Technologies, Inc., Redmond, Washington, United States of America
| | - Laura M. Gustavson
- Kestra Medical Technologies, Inc., Redmond, Washington, United States of America
| | - Jeanne E. Poole
- Division of Cardiology, Department of Medicine, University of Washington School of Medicine, Seattle, Washington, United States of America
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Neuber JU, Varghese F, Pakhomov AG, Zemlin CW. Using Nanosecond Shocks for Cardiac Defibrillation. Bioelectricity 2019; 1:240-246. [PMID: 32685917 DOI: 10.1089/bioe.2019.0030] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The purpose of this review article is to summarize our current understanding of the efficacy and safety of cardiac defibrillation with nanosecond shocks. Experiments in isolated hearts, using optical mapping of the electrical activity, have demonstrated that nanosecond shocks can defibrillate with lower energies than conventional millisecond shocks. Single defibrillation strength nanosecond shocks do not cause obvious damage, but repeated stimulation leads to deterioration of the hearts. In isolated myocytes, nanosecond pulses can also stimulate at lower energies than at longer pulses and cause less electroporation (propidium uptake). The mechanism is likely electroporation of the plasma membrane. Repeated stimulation leads to distorted calcium gradients.
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Affiliation(s)
- Johanna U Neuber
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, Virginia.,Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia
| | - Frency Varghese
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Andrei G Pakhomov
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, Virginia
| | - Christian W Zemlin
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, Virginia.,Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia
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Semenov I, Grigoryev S, Neuber JU, Zemlin CW, Pakhomova ON, Casciola M, Pakhomov AG. Excitation and injury of adult ventricular cardiomyocytes by nano- to millisecond electric shocks. Sci Rep 2018; 8:8233. [PMID: 29844431 PMCID: PMC5974370 DOI: 10.1038/s41598-018-26521-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 05/08/2018] [Indexed: 12/13/2022] Open
Abstract
Intense electric shocks of nanosecond (ns) duration can become a new modality for more efficient but safer defibrillation. We extended strength-duration curves for excitation of cardiomyocytes down to 200 ns, and compared electroporative damage by proportionally more intense shocks of different duration. Enzymatically isolated murine, rabbit, and swine adult ventricular cardiomyocytes (VCM) were loaded with a Ca2+ indicator Fluo-4 or Fluo-5N and subjected to shocks of increasing amplitude until a Ca2+ transient was optically detected. Then, the voltage was increased 5-fold, and the electric cell injury was quantified by the uptake of a membrane permeability marker dye, propidium iodide. We established that: (1) Stimuli down to 200-ns duration can elicit Ca2+ transients, although repeated ns shocks often evoke abnormal responses, (2) Stimulation thresholds expectedly increase as the shock duration decreases, similarly for VCMs from different species, (3) Stimulation threshold energy is minimal for the shortest shocks, (4) VCM orientation with respect to the electric field does not affect the threshold for ns shocks, and (5) The shortest shocks cause the least electroporation injury. These findings support further exploration of ns defibrillation, although abnormal response patterns to repetitive ns stimuli are of a concern and require mechanistic analysis.
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Affiliation(s)
- Iurii Semenov
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, 23508, USA
| | - Sergey Grigoryev
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, 23508, USA
| | - Johanna U Neuber
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, 23508, USA.,Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, VA, 23508, USA
| | - Christian W Zemlin
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, 23508, USA.,Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, VA, 23508, USA
| | - Olga N Pakhomova
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, 23508, USA
| | - Maura Casciola
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, 23508, USA
| | - Andrei G Pakhomov
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, 23508, USA.
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Defibrillation for Ventricular Fibrillation: A Shocking Update. J Am Coll Cardiol 2017; 70:1496-1509. [PMID: 28911514 DOI: 10.1016/j.jacc.2017.07.778] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 07/24/2017] [Indexed: 01/09/2023]
Abstract
Cardiac arrest is defined as the termination of cardiac activity associated with loss of consciousness, of spontaneous breathing, and of circulation. Sudden cardiac arrest and sudden cardiac death (SCD) are terms often used interchangeably. Most patients with out-of-hospital cardiac arrest have shown coronary artery disease or symptoms during the hour before the event. Cardiac arrest is potentially reversible by cardiopulmonary resuscitation, defibrillation, cardioversion, cardiac pacing, or treatments targeted at the underlying disease (e.g., acute coronary occlusion). We restrict SCD hereafter to cardiac arrest due to ventricular fibrillation, including rhythms shockable by an automatic external defibrillator (AED), implantable cardioverter-defibrillator (ICD), or wearable cardioverter-defibrillator (WCD). We summarize the state of the art related to defibrillation in treating SCD, including a brief history of the evolution of defibrillation, technical characteristics of modern AEDs, strategies to improve AED access and increase survival, ancillary treatments, and use of ICDs or WCDs.
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7
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Anantharaman V, Wan PW, Tay SY, Manning PG, Lim SH, Chua SJT, Mohan T, Rabind AC, Vidya S, Hao Y. Role of peak current in conversion of patients with ventricular fibrillation. Singapore Med J 2017; 58:432-437. [PMID: 28741007 DOI: 10.11622/smedj.2017070] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
INTRODUCTION Peak currents are the final arbiter of defibrillation in patients with ventricular fibrillation (VF). However, biphasic defibrillators continue to use energy in joules for electrical conversion in hopes that their impedance compensation properties will address transthoracic impedance (TTI), which must be overcome when a fixed amount of energy is delivered. However, optimal peak currents for conversion of VF remain unclear. We aimed to determine the role of peak current and optimal peak levels for conversion in collapsed VF patients. METHODS Adult, non-pregnant patients presenting with non-traumatic VF were included in the study. All defibrillations that occurred were included. Impedance values during defibrillation were used to calculate peak current values. The endpoint was return of spontaneous circulation (ROSC). RESULTS Of the 197 patients analysed, 105 had ROSC. Characteristics of patients with and without ROSC were comparable. Short duration of collapse < 10 minutes correlated positively with ROSC. Generally, patients with average or high TTI converted at lower peak currents. 25% of patients with high TTI converted at 13.3 ± 2.3 A, 22.7% with average TTI at 18.2 ± 2.5 A and 18.6% with low TTI at 27.0 ± 4.7 A (p = 0.729). Highest peak current conversions were at < 15 A and 15-20 A. Of the 44 patients who achieved first-shock ROSC, 33 (75.0%) received < 20 A peak current vs. > 20 A for the remaining 11 (25%) patients (p = 0.002). CONCLUSION For best effect, priming biphasic defibrillators to deliver specific peak currents should be considered.
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Affiliation(s)
| | - Paul Weng Wan
- Department of Emergency Medicine, Singapore General Hospital, Singapore
| | - Seow Yian Tay
- Emergency Department, Tan Tock Seng Hospital, Singapore
| | | | - Swee Han Lim
- Department of Emergency Medicine, Singapore General Hospital, Singapore
| | | | - Tiru Mohan
- Accident and Emergency Department, Changi General Hospital, Singapore
| | | | - Sudarshan Vidya
- Department of Emergency Medicine, Singapore General Hospital, Singapore
| | - Ying Hao
- Health Services Research Unit, Singapore General Hospital, Singapore
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Wan C, Szymkiewicz SJ, Klein HU. The impact of body mass index on the wearable cardioverter defibrillator shock efficacy and patient wear time. Am Heart J 2017; 186:111-117. [PMID: 28454824 DOI: 10.1016/j.ahj.2017.01.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 01/12/2017] [Indexed: 10/20/2022]
Abstract
BACKGROUND The impact of body mass index (BMI) on the shock efficacy and patient adherence among patients using a wearable cardioverter defibrillator (WCD) is unknown. METHODS Patients prescribed the WCD between January 1, 2008 and June 1, 2013, who experienced at least one episode of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) and who received appropriate WCD therapy, were identified within a registry maintained by the manufacturer for regulatory, reimbursement, and administrative purposes. The registry contained patients' Body Mass Index (BMI) which was categorized as normal (18.0<BMI<25.0), overweight (25.0≤BMI<30.0) or obese (30.0≥BMI). Demographics, indication for WCD prescription and other clinical information were reviewed. Device-stored ECG, transthoracic impedance (TTI) and time worn were downloaded for analyses. A post-shock rhythm which was no longer VT or VF was considered a successful tachyarrhythmia conversion. Only the first-shock arrhythmia conversion and TTI were included in the analyses. RESULTS A total of 574 patients were included in the final analyses. Patient characteristics were similar across all groups except the obese group (60±11 years) was younger than the normal (63±16 years) and overweight (64±12 years, P=.001) groups. Mean length of use for normal, overweight and obese groups was 79±131, 82±202 and 55±97 days (P=.12), respectively; the median daily wear time was 21 hours among all groups. In a total of 623 VT/VF events, the median TTI was 44 ohms, 51 ohms and 65 ohms for normal, overweight and obese groups, respectively; TTI was positively correlated to BMI (r=0.33, P<.01). First-shock conversion rate was 92.9% in the normal group, 93.6% and 93.9% in the overweight and obese groups, respectively (P=.93). There was no difference in 24-hour survival among the three groups (91.9%, 94.1% and 92.3%, P=.66). CONCLUSION The WCD first-shock success rate and post-event 24-hour survival were high and independent from BMI. TTI was positively correlated with BMI but did not impact early clinical outcome. WCD was safe to all BMI groups and the patient wear time was excellent across all groups.
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9
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Faddy SC, Jennings PA. Biphasic versus monophasic waveforms for transthoracic defibrillation in out-of-hospital cardiac arrest. Cochrane Database Syst Rev 2016; 2:CD006762. [PMID: 26904970 PMCID: PMC8454037 DOI: 10.1002/14651858.cd006762.pub2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND Transthoracic defibrillation is a potentially life-saving treatment for people with ventricular fibrillation (VF) and haemodynamically unstable ventricular tachycardia (VT). In recent years, biphasic waveforms have become more commonly used for defibrillation than monophasic waveforms. Clinical trials of internal defibrillation and transthoracic defibrillation of short-duration arrhythmias of up to 30 seconds have demonstrated the superiority of biphasic waveforms over monophasic waveforms. However, out-of-hospital cardiac arrest (OHCA) involves a duration of VF/VT of several minutes before defibrillation is attempted. OBJECTIVES To determine the efficacy and safety of biphasic defibrillation waveforms, compared to monophasic, for resuscitation of people experiencing out-of-hospital cardiac arrest. SEARCH METHODS We searched the following electronic databases for potentially relevant studies up to 10 September 2014: the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE. Also we checked the bibliographies of relevant studies and review articles, contacted authors of published reviews and reviewed webpages (including those of device manufacturers) relevant to the review topic. We handsearched the abstracts of conference proceedings for the American Heart Association, American College of Cardiology, European Society of Cardiology, European Resuscitation Council, Society of Critical Care Medicine and European Society of Intensive Care Medicine. Regarding language restrictions, we did not apply any. SELECTION CRITERIA We included randomised controlled trials (RCTs) that compared biphasic and monophasic waveform defibrillation in adults with OHCA. Two review authors independently screened the literature search results. DATA COLLECTION AND ANALYSIS Two review authors independently extracted data from the included trials and performed 'Risk of bias' assessments. We resolved any disagreements by discussion and consensus. The primary outcome was the risk of failure to achieve return of spontaneous circulation (ROSC). Secondary outcomes included risk of failure to revert VF to an organised rhythm following the first shock or up to three shocks, survival to hospital admission and survival to discharge. MAIN RESULTS We included four trials (552 participants) that compared biphasic and monophasic waveform defibrillation in people with OHCA. Based on the assessment of five quality domains, we identified two trials that were at high risk of bias, one trial at unclear risk of bias and one trial at low risk of bias. The risk ratio (RR) for failure to achieve ROSC after biphasic compared to monophasic waveform defibrillation was 0.86 (95% CI 0.62 to 1.20; four trials, 552 participants). The RR for failure to defibrillate on the first shock following biphasic defibrillation compared to monophasic was 0.84 (95% CI 0.70 to 1.01; three trials, 450 participants); and 0.81 (95% CI 0.61 to 1.09; two trials, 317 participants) for one to three stacked shocks. The RR for failure to achieve ROSC after the first shock was 0.92 (95% CI 0.81 to 1.04; two trials, 285 participants). Biphasic waveforms did not reduce the risk of death before hospital admission (RR 1.05, 95% CI 0.90 to 1.23; three trials, 383 participants) or before hospital discharge (RR 1.05, 95% CI 0.78 to 1.42; four trials, 550 participants). There was no statistically significant heterogeneity in any of the pooled analyses. None of the included trials reported adverse events. AUTHORS' CONCLUSIONS It is uncertain whether biphasic defibrillators have an important effect on defibrillation success in people with OHCA. Further large studies are needed to provide adequate statistical power.
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Affiliation(s)
- Steven C Faddy
- Service Development and Planning, Ambulance Service of NSW, Locked Bag 105, Rozelle, NSW, Australia, 2039
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Tanabe S, Yasunaga H, Koike S, Akahane M, Ogawa T, Horiguchi H, Hatanaka T, Yokota H, Imamura T. Monophasic versus biphasic defibrillation for pediatric out-of-hospital cardiac arrest patients: a nationwide population-based study in Japan. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2012; 16:R219. [PMID: 23148767 PMCID: PMC3672598 DOI: 10.1186/cc11864] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 11/09/2012] [Indexed: 01/11/2023]
Abstract
Introduction Conventional monophasic defibrillators for out-of-hospital cardiac-arrest patients have been replaced with biphasic defibrillators. However, the advantage of biphasic over monophasic defibrillation for pediatric out-of-hospital cardiac-arrest patients remains unknown. This study aimed to compare the survival outcomes of pediatric out-of-hospital cardiac-arrest patients who underwent monophasic defibrillation with those who underwent biphasic defibrillation. Methods This prospective, nationwide, population-based observational study included pediatric out-of-hospital cardiac-arrest patients from January 1, 2005, to December 31, 2009. The primary outcome measure was survival at 1 month with minimal neurologic impairment. The secondary outcome measures were survival at 1 month and the return of spontaneous circulation before hospital arrival. Multivariable logistic regression analysis was performed to identify the independent association between defibrillator type (monophasic or biphasic) and outcomes. Results Among 5,628 pediatric out-of-hospital cardiac-arrest patients (1 through 17 years old), 430 who received defibrillation shock with monophasic or biphasic defibrillator were analyzed. The number of patients who received defibrillation shock with monophasic defibrillator was 127 (30%), and 303 (70%) received defibrillation shock with biphasic defibrillator. The survival rates at 1 month with minimal neurologic impairment were 17.5% and 24.4%, the survival rates at 1 month were 32.3% and 35.6%, and the rates of return of spontaneous circulation before hospital arrival were 24.4% and 27.4% in the monophasic and biphasic defibrillator groups, respectively. Hierarchic logistic regression analyses by using generalized estimation equations found no significant difference between the two groups in terms of 1-month survival with minimal neurologic impairment (odds ratio (OR), 1.57; 95% confidence interval (CI), 0.87 to 2.83; P = 0.14) and 1-month survival (OR, 1.38; 95% CI, 0.87 to 2.18; P = 0.17). Conclusions The present nationwide population-based observational study could not confirm an advantage of biphasic over monophasic defibrillators for pediatric OHCA patients.
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Sultan A, Steven D, Rostock T, Hoffmann B, Müllerleile K, Servatius H, Drewitz I, Lüker J, Meyer P, Salukhe T, Willems S. Intravenous administration of magnesium and potassium solution lowers energy levels and increases success rates electrically cardioverting atrial fibrillation. J Cardiovasc Electrophysiol 2011; 23:54-9. [PMID: 21815963 DOI: 10.1111/j.1540-8167.2011.02146.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND External biphasic electrical cardioversion (CV) is a standard treatment option for patients suffering from acute symptoms of atrial fibrillation (AF). Nevertheless, CV is not always successful, and thus strategies to increase the success rate are desirable. OBJECTIVE The purpose of this study was to evaluate the effect of intravenously administered K/Mg solution on the biphasic CV energy threshold and success rate to restore sinus rhythm (SR) in patients with AF. METHODS The study consisted of 170 patients with persistent AF. The patients were randomly assigned to undergo biphasic CV either with (n = 84) or without (n = 86) pretreatment with K/Mg solution. An energy step-up protocol of 75, 100, and 150 W (J) was used. RESULTS Biphasic CV of AF was effective in 81 (96.4%) patients in the pretreatment and 74 (86.0%) patients in the control group (P = 0.005). The effective energy level required to achieve SR was significantly lower in the pretreated group (140.8 ± 26.9 J vs 182.5 ± 52.2 J, P = 0.02). No K/Mg-solution-associated side effects such as hypotension or bradycardia were observed. CONCLUSION Administration of K/Mg solution positively influences the success rate of CV in patients with persistent AF. Furthermore, significantly less energy is required to successfully restore SR and therefore K/Mg pretreatment may facilitate SR restoration in patients undergoing CV for AF.
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Affiliation(s)
- Arian Sultan
- Cardiac Electrophysiology, University Hospital Hamburg-Eppendorf, Hamburg, Germany.
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12
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Abstract
Severe burns result in a profound hypermetabolic response. Catecholaminergic surges secondary to the burn injury itself, particularly if superimposed on premorbid cardiac disease, can result in cardiac arrhythmias. If unstable, these cardiac rhythm disturbances necessitate immediate cardioversion to regain normal sinus rhythm. Because of the high impedance at the skin-paddle interface, superficial cutaneous burns have been known to develop secondary to cardioversion. The authors describe a novel case of the subsequent local progression of a previously sustained superficial flame burn to full-thickness burn injury after cardioversion.
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Rumeau P, Fourcade J, Duparc A, Hébrard A, Mondoly P, Rollin A, Massabuau P, Detis N, Elbaz M, Carrié D, Galinier M, Delay M, Maury P. ST-segment changes after direct current external cardioversion for atrial fibrillation. Incidence, characteristics and predictive factors. Int J Cardiol 2011; 148:341-6. [DOI: 10.1016/j.ijcard.2009.11.031] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Revised: 10/17/2009] [Accepted: 11/29/2009] [Indexed: 11/17/2022]
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Ferreira M, de Abreu LC, Valenti VE, Meneghini A, Murad N, Ferreira C. Electric countershock and cold stress effects on liver and adrenal gland. Clinics (Sao Paulo) 2010; 65:291-6. [PMID: 20360920 PMCID: PMC2845770 DOI: 10.1590/s1807-59322010000300009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Accepted: 11/26/2009] [Indexed: 11/26/2022] Open
Abstract
OBJECTIVES Cold exposure induces glycogen and lipid depletion in the liver and the adrenal gland, respectively. However, no previous study has determined the effects of electrical countershock on those tissues. We aimed to evaluate the effects of electrical countershock on lipid depletion in the adrenal gland and on glycogen depletion in the liver. METHODS We used 40 male Wistar rats divided into four groups: the control group, in which the animals were subjected to a resting period of seven days; the electrical discharge group, in which the animals were subjected to a resting period followed by administration of ten 300-mV electrical discharges; the electrical post-discharge group, in which the animals received ten electrical shocks (300 mV) followed by rest for seven consecutive days; and the cold stress group, in which the animals were subjected to a resting period and were then exposed to -8 degrees C temperatures for four hours. All animals underwent a laparotomy after treatment. The lipid and glycogen depletions are presented using intensity levels (where + = low intensity and ++++ = high intensity, with intermediate levels in between). RESULTS The rats exposed to the cold stress presented the highest glycogen and lipid depletion in the liver and the adrenal gland, respectively. Furthermore, we noted that the electrical countershock significantly increased lipid depletion in the adrenal gland and glycogen depletion in the liver. One week after the electrical countershock, the liver and adrenal gland profiles were similar to that of the control group. CONCLUSION Electrical countershock immediately increased the glycogen depletion in the liver and the lipid depletion in the adrenal gland of rats.
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Affiliation(s)
- Marcelo Ferreira
- Departamento de Clínica Médica, Disciplina de Cardiologia, Faculdade de Medicina do ABC - Santo André/SP, Brazil
- Departamento de Medicina, Disciplina de Cardiologia, Universidade Federal de São Paulo (UNIFESP) - São Paulo/SP, Brazil
| | - Luiz Carlos de Abreu
- Departamento de Morfologia e Fisiologia, Faculdade de Medicina do ABC - Santo André/SP, Brazil
| | - Vitor E. Valenti
- Departamento de Medicina, Disciplina de Cardiologia, Universidade Federal de São Paulo (UNIFESP) - São Paulo/SP, Brazil
| | - Adriano Meneghini
- Departamento de Clínica Médica, Disciplina de Cardiologia, Faculdade de Medicina do ABC - Santo André/SP, Brazil
| | - Neif Murad
- Departamento de Clínica Médica, Disciplina de Cardiologia, Faculdade de Medicina do ABC - Santo André/SP, Brazil
| | - Celso Ferreira
- Departamento de Clínica Médica, Disciplina de Cardiologia, Faculdade de Medicina do ABC - Santo André/SP, Brazil
- Departamento de Medicina, Disciplina de Cardiologia, Universidade Federal de São Paulo (UNIFESP) - São Paulo/SP, Brazil
- , Tel.: 55 11 4993.5403
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Ferreira M, Ferreira C, de Abreu LC, Valenti VE, Murad N, Meneghini A, Filho CF, Filho JADO. Myocardium tissue changes caused by electrical transthoracic discharges in rats. Int Arch Med 2009; 2:31. [PMID: 19852820 PMCID: PMC2771001 DOI: 10.1186/1755-7682-2-31] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Accepted: 10/23/2009] [Indexed: 11/25/2022] Open
Abstract
Background Cardiomyocytes cytoarchitecture changes caused by transthoracic countershocks have been focused recently. We aimed to evaluate the effects of electrical discharge application in the mitochondria structure in atrial myocardium of rats. Methods An electrical cardioverter was adapted to small rodent animals for our research. Electrical discharges were applied to the precordial region of 30 albino rats: (1) control group - animals that remained on resting period and were afterwards sacrificed; (2) electrical discharge group - animals that remained on resting period, followed by ten electrical discharges of 300 mV and sacrificed, and; (3) electrical post-discharge group - animals that remained on a resting period and received ten electrical discharges like the electrical discharge group, but were sacrificed seven days subsequently. We examined liver, adrenal and left atrium tissue fragments of the three groups. Results It was observed in control and post-discharge groups a normal cellular structure aspect with preserved architecture of cardiomyocytes and continuous sarcoplasmic membrane integrity. On the other hand, cardiac muscle fibers with mitochondrial edema and lysis occurred in the discharge group. Glycogen and adrenal lipids were not depleted in all groups. Conclusion These data suggest that transthoracic electrical discharges induce mitochondrial injuries in atrial cardiac cells of rats.
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Affiliation(s)
- Marcelo Ferreira
- Department of Clinical Medicine, Cardiology Division, School of Medicine of ABC, Santo André, SP, Brazil.
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Li Y, Wang H, Cho JH, Didon JP, Bisera J, Weil MH, Tang W. Comparison of efficacy of pulsed biphasic waveform and rectilinear biphasic waveform in a short ventricular fibrillation pig model. Resuscitation 2009; 80:1047-51. [DOI: 10.1016/j.resuscitation.2009.05.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2008] [Revised: 05/12/2009] [Accepted: 05/15/2009] [Indexed: 11/15/2022]
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Stothert JC, Hatcher TS, Gupton CL, Love JE, Brewer JE. RECTILINEARBIPHASICWAVEFORMDEFIBRILLATION OFOUT-OF-HOSPITALCARDIACARREST. PREHOSP EMERG CARE 2009. [DOI: 10.1080/312704000760] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Ristagno G, Tang W, Weil MH. Cardiopulmonary resuscitation: from the beginning to the present day. Crit Care Clin 2009; 25:133-51, ix. [PMID: 19268799 DOI: 10.1016/j.ccc.2008.10.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Cardiac arrest represents a dramatic event that can occur suddenly and often without premonitory signs, characterized by sudden loss of consciousness and breathing after cardiac output ceases and both coronary and cerebral blood flows stop. Restarting of the blood flow by cardiopulmonary resuscitation potentially re-establishes some cardiac output and organ blood flows. This article summarizes the major events that encompass the history of cardiopulmonary resuscitation, beginning with ancient history and evolving into the current American Heart Association's commitment to save hearts.
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MESH Headings
- Animals
- Biomedical Research/history
- Cardiac Pacing, Artificial/history
- Cardiopulmonary Resuscitation/history
- Cardiopulmonary Resuscitation/instrumentation
- Cardiopulmonary Resuscitation/methods
- Cardiopulmonary Resuscitation/standards
- Cats
- Critical Care/history
- Dogs
- Electric Countershock/history
- Global Health
- Heart Arrest/history
- Heart Arrest/therapy
- Heart Massage/history
- Heart Massage/methods
- History, 16th Century
- History, 17th Century
- History, 18th Century
- History, 19th Century
- History, 20th Century
- History, 21st Century
- History, Ancient
- Humans
- Models, Animal
- Near Drowning/history
- Near Drowning/therapy
- Practice Guidelines as Topic
- Respiration, Artificial/history
- Respiration, Artificial/instrumentation
- Respiration, Artificial/methods
- Ventilators, Mechanical/history
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Affiliation(s)
- Giuseppe Ristagno
- Weil Institute of Critical Care Medicine, 35100 Bob Hope Drive, Rancho Mirage, CA 92270, USA
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Abstract
External electrical cardioversion was first performed in the 1950s. Urgent or elective cardioversions have specific advantages, such as termination of atrial and ventricular tachycardia and recovery of sinus rhythm. Electrical cardioversion is life-saving when applied in urgent circumstances. The succcess rate is increased by accurate tachycardia diagnosis, careful patient selection, adequate electrode (paddles) application, determination of the optimal energy and anesthesia levels, prevention of embolic events and arrythmia recurrence and airway conservation while minimizing possible complications. Potential complications include ventricular fibrillation due to general anesthesia or lack of synchronization between the direct current (DC) shock and the QRS complex, thromboembolus due to insufficient anticoagulant therapy, non-sustained VT, atrial arrhythmia, heart block, bradycardia, transient left bundle branch block, myocardial necrosis, myocardial dysfunction, transient hypotension, pulmonary edema and skin burn. Electrical cardioversion performed in patients with a pacemaker or an incompatible cardioverter defibrillator may lead to dysfunction, namely acute or chronic changes in the pacing or sensitivity threshold. Although this procedure appears fairly simple, serious consequences might occur if inappropriately perfformed.
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Affiliation(s)
- Murat Sucu
- Department of Cardiology, Gaziantep University School of Medicine, Gaziantep, Turkey
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Mortensen K, Risius T, Schwemer TF, Aydin MA, Köster R, Klemm HU, Lutomsky B, Meinertz T, Ventura R, Willems S. Biphasic versus Monophasic Shock for External Cardioversion of Atrial Flutter. Cardiology 2008; 111:57-62. [DOI: 10.1159/000113429] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Accepted: 09/21/2007] [Indexed: 11/19/2022]
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Abstract
In this article, electrical and pharmacologic cardioversion for atrial fibrillation is described in detail. Indications for cardioversion and management of pericardioversion anticoagulation also are discussed. Finally, management strategies for immediate recurrence of atrial fibrillation and cardioversion failure are offered.
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Affiliation(s)
- Susan S Kim
- Clinical Cardiac Electrophysiology, Section of Cardiology, Department of Medicine, University of Chicago Hospitals, University of Chicago, 5758 South Maryland Avenue MC9024, Chicago, IL 60637, USA
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Faddy S, Jennings P, Cunningham R, Sen A. Biphasic versus monophasic waveforms for transthoracic defibrillation in out-of-hospital cardiac arrest. THE COCHRANE DATABASE OF SYSTEMATIC REVIEWS 2007. [DOI: 10.1002/14651858.cd006762] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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24
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ARGUS PRO LifeCare®. Notf Rett Med 2007. [DOI: 10.1007/s10049-007-0920-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Ambler JJS, Deakin CD. A randomised controlled trial of the effect of biphasic or monophasic waveform on the incidence and severity of cutaneous burns following external direct current cardioversion. Resuscitation 2006; 71:293-300. [PMID: 16996194 DOI: 10.1016/j.resuscitation.2006.04.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2005] [Revised: 04/12/2006] [Accepted: 04/12/2006] [Indexed: 10/24/2022]
Abstract
OBJECTIVE Cutaneous burns are a common cause of morbidity following direct current (DC) cardioversion. We designed a prospective randomised double-blinded controlled study to determine the effect of biphasic or monophasic waveform on the pain and inflammation occurring after elective cardioversion. MATERIALS AND METHODS One hundred and thirty nine patients undergoing elective DC cardioversion were randomised to receive monophasic (HP Codemaster XL; 100, 200, 300, 360, and 360 J) or biphasic (Welch Allyn-MRL PIC defibrillator; 70, 100, 150, 200, and 300 J) waveforms. Two hours after DC cardioversion, skin temperature, erythema index and sensory threshold to light and sharp touch was measured at the centre and edge of paddle sites. Visual analogue pain score (VAS) was recorded at 2 and 24 h. RESULTS There was significantly less pain following biphasic cardioversion as assessed by VAS at both 2 h (p < 0.001; 95% confidence intervals of difference of medians (CI) 0.2-0.8 cm) and 24 h (p = 0.004; 95% CI 0.0-0.4 cm). There was significantly less erythema in patients receiving biphasic cardioversion at the edge of the sternal site (p = 0.046; 95% CI 0.41-4.5). There was no difference in any other variable at any site between biphasic and monophasic cardioversion. CONCLUSION The use of a biphasic waveform for DC cardioversion reduces the inflammation and pain of burns as measured by erythema index and visual analogue scale.
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Affiliation(s)
- Jonathan J S Ambler
- Shackleton Department of Anaesthetics, Southampton University Hospitals NHS Trust, Tremona Road, Southampton SO16 6YD, UK.
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Ambler JJS, Deakin CD. A randomized controlled trial of efficacy and ST change following use of the Welch-Allyn MRL PIC biphasic waveform versus damped sine monophasic waveform for external DC cardioversion. Resuscitation 2006; 71:146-51. [PMID: 16987583 DOI: 10.1016/j.resuscitation.2006.03.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2006] [Accepted: 03/30/2006] [Indexed: 11/15/2022]
Abstract
OBJECTIVE Biphasic waveforms have similar or greater efficacy at cardioverting atrial and ventricular arrhythmias at lower energy levels than monophasic waveforms, and cause less ST depression following defibrillation of ventricular fibrillation. No studies have investigated this effect on ST change with atrial arrhythmias. We studied the efficacy of the Welch Allyn-MRL PIC biphasic defibrillator. METHODS One hundred and thirty-nine patients undergoing elective DC cardioversion for atrial arrhythmias were randomised to cardioversion by monophasic (Hewlett Packard Codemaster XL; 100, 200, 300, 360 and 360J) or biphasic (Welch Allyn-MRL PIC; 70, 100, 150, 200 and 300J) defibrillator. We analysed success of cardioversion after 0 and 30min, cumulative energy, number of shocks and energy at successful cardioversion. The ST change in the recorded electrocardiogram was measured at 15s after all shocks using electronic callipers. RESULTS Immediately after cardioversion 59/68 (86.8%) of the monophasic group versus 56/60 (93.3%) of the biphasic group were in sinus rhythm. Of the monophasic group, 55/67 (82.1%) remained in sinus rhythm at 30min versus 53/58 (91.4%) of the biphasic group. These differences were not significant at 0min (P=0.35) or 30min (P=0.21). The biphasic group required significantly fewer shocks (P=0.006), less cumulative energy (P<0.0001) and required lower total energy for successful cardioversion (P<0.0001). Of the 102 patients with electrocardiogram recordings suitable for analysis, ST segment change was greater in the monophasic group (P=0.037). CONCLUSIONS The Welch Allyn-MRL biphasic waveform for DC cardioversion results in fewer shocks, with less cumulative energy delivered and less post shock ST change than with a Hewlett Packard Codemaster XL damped sine wave monophasic waveform.
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Affiliation(s)
- Jonathan J S Ambler
- Shackleton Department of Anaesthetics, Southampton University Hospitals NHS Trust, Southampton SO16 6YD, UK.
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27
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Faddy SC. Reconfirmation algorithms should be the standard of care in automated external defibrillators. Resuscitation 2006; 68:409-15. [PMID: 16387407 DOI: 10.1016/j.resuscitation.2005.07.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2005] [Revised: 07/13/2005] [Accepted: 07/19/2005] [Indexed: 10/25/2022]
Abstract
Non-sustained and self-terminating arrhythmias pose a significant challenge during resuscitation. Delivery of a defibrillation shock to a non-shockable rhythm has a poorly understood effect on the heart. The importance of assessing rhythm right up until the delivery of a shock is of increased importance when "blind" shocks are being delivered by automatic defibrillators or minimally trained rescuers. Reconfirmation algorithms are common in current-generation implantable defibrillators but this investigation of current-generation AEDs shows that only 71% of devices presently available have reconfirmation algorithms. A case of spontaneous reversion of a non-sustained arrhythmia is presented. The implications of delivering a defibrillator shock to a non-shockable rhythm are discussed.
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Affiliation(s)
- Steven C Faddy
- Cardiology Department. St Vincent's Hospital, Sydney, Victoria Street, Darlinghurst, NSW 2010, Australia.
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Burke MC, Coman JA, Cates AW, Lindstrom CC, Sandler DA, Kim SS, Knight BP. Defibrillation energy requirements using a left anterior chest cutaneous to subcutaneous shocking vector: Implications for a total subcutaneous implantable defibrillator. Heart Rhythm 2005; 2:1332-8. [PMID: 16360086 DOI: 10.1016/j.hrthm.2005.09.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2005] [Accepted: 09/06/2005] [Indexed: 11/23/2022]
Abstract
BACKGROUND Subcutaneous implantable defibrillators (ICDs) are being developed to facilitate ICD implantation. OBJECTIVE The purpose of this study was to estimate the human defibrillation energy requirement (DER) using a left chest cutaneous (Q) to subcutaneous (SQ) shocking vector. METHODS Twenty patients undergoing implantation of an indicated ICD were enrolled (15 males, age = 63 +/- 12 years; ejection fraction = 0.27 +/- 0.14). Defibrillation testing was performed using an investigational system consisting of an external defibrillator and a constructed connector to deliver a shock between a pectoral SQ can and a cardiac apical Q electrode. Two attempts at defibrillation using this configuration were allowed. Stage 1 testing started at 70 J with a step-down/step-up to 50 or 100 J, respectively. Stage 2 testing began at 50 J with a step-down/step-up to 30 or 70 J. RESULTS During stage 1, a 70-J shock was successful in 7/9 (78%) patients. A second attempt was successful in 7/7 patients using a 50-J shock. In the two remaining patients, a second attempt using a 100-J shock was successful. During stage 2, a 50-J shock was successful in 10/11 (91%) patients. The protocol could not be completed in 2/11 patients. Of the remaining nine patients, a second defibrillation was successful in seven (78%) using a 30-J shock. CONCLUSIONS The defibrillation energy requirement (DER) of this study vector was 50 J or less in most patients. This low DER supports further investigation of a totally SQ-ICD. However, the DER of 100 J in two patients indicates that further investigation is needed regarding DER variability and safety margins.
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Affiliation(s)
- Martin C Burke
- Section of Cardiology, Department of Internal Medicine, University of Chicago, Illinois 60637, USA.
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Affiliation(s)
- Michael Kyller
- Michael Kyller is the charge nurse in the cardiac catheterization laboratory at Boston Medical Center, Boston, Mass. He is an American Heart Association Basic Life Support instructor and course coordinator and is Regional Faculty for Basic Life Support and Advanced Cardiac Life Support
| | - Donald Johnstone
- Donald Johnstone is a clinical instructor in the telemetry units at Boston Medical Center, Boston, Mass. He is an American Heart Association Basic Life Support instructor and course coordinator
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Morrison LJ, Dorian P, Long J, Vermeulen M, Schwartz B, Sawadsky B, Frank J, Cameron B, Burgess R, Shield J, Bagley P, Mausz V, Brewer JE, Lerman BB. Out-of-hospital cardiac arrest rectilinear biphasic to monophasic damped sine defibrillation waveforms with advanced life support intervention trial (ORBIT). Resuscitation 2005; 66:149-57. [PMID: 15992986 DOI: 10.1016/j.resuscitation.2004.11.031] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2004] [Revised: 11/24/2004] [Accepted: 11/24/2004] [Indexed: 11/20/2022]
Abstract
BACKGROUND Although biphasic defibrillation waveforms appear to be superior to monophasic waveforms in terminating VF, their relative benefits in out-of-hospital resuscitation are incompletely understood. Prior comparisons of defibrillation waveform efficacy in out-of-hospital cardiac arrest (OHCA) are confined to patients presenting in a shockable rhythm and resuscitated by first responder (basic life support). This effectiveness study compared monophasic and biphasic defibrillation waveform for conversion of ventricular arrhythmias in all OHCA treated with advance life support (ALS). METHODS AND RESULTS This prospective randomized controlled trial compared the rectilinear biphasic (RLB) waveform with the monophasic damped sine (MDS) waveform, using step-up energy levels. The study enrolled OHCA patients requiring at least one shock delivered by ALS providers, regardless of initial presenting rhythm. Shock success was defined as conversion at 5s to organized rhythm after one to three escalating shocks. We report efficacy results for the cohort of patients treated by ALS paramedics who presented with an initially shockable rhythm who had not received a shock from a first responder (MDS: n=83; RLB: n=86). Shock success within the first three ascending energy shocks for RLB (120, 150, 200J) was superior to MDS (200, 300, 360J) for patients initially presenting in a shockable rhythm (52% versus 34%, p=0.01). First shock conversion was 23% and12%, for RLB and MDS, respectively (p=0.07). There were no significant differences in return of spontaneous circulation (47% versus 47%), survival to 24h (31% versus 27%), and survival to discharge (9% versus 7%). Mean 24h survival rates of bystander witnessed events showed differences between waveforms in the early circulatory phase at 4-10 min post event (mean (S.D.) RLB 0.45 (0.07) versus MDS 0.31 (0.06), p=0.0002) and demonstrated decline as time to first shock increased to 20 min. CONCLUSION Shock success to an organized rhythm comparing step-up protocol for energy settings demonstrated the RLB waveform was superior to MDS in ALS treatment of OHCA. Survival rates for both waveforms are consistent with current theories on the circulatory and metabolic phases of out-of-hospital cardiac arrest.
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Affiliation(s)
- Laurie J Morrison
- Prehospital and Transport Medicine Research Program, Sunnybrook and Women's College Health Sciences Centre, Institute for Clinical and Evaluative Sciences, Department of Medicine, University of Toronto, Toronto, Ont., Canada.
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Qu F, Zarubin F, Wollenzier B, Nikolski VP, Efimov IR. The Gurvich waveform has lower defibrillation threshold than the rectilinear waveform and the truncated exponential waveform in the rabbit heart. Can J Physiol Pharmacol 2005; 83:152-60. [PMID: 15791288 DOI: 10.1139/y04-131] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Implantable cardioverter defibrillator studies have established the superiority of biphasic waveforms over monophasic waveforms. However, external defibrillator studies of biphasic waveforms are not as widespread. Our objective was to compare the defibrillation efficacy of clinically used biphasic waveforms, i.e., truncated exponential, rectilinear, and quasi-sinusoidal (Gurvich) waveforms in a fibrillating heart model. Langendorff-perfused rabbit hearts (n = 10) were stained with a voltage-sensitive fluorescent dye, Di-4-ANEPPS. Transmembrane action potentials were optically mapped from the anterior epicardium. We found that the Gurvich waveform was significantly superior (p < 0.05) to the rectilinear and truncated exponential waveforms. The defibrillation thresholds (mean +/- SE) were as follows: Gurvich, 0.25 +/- 0.01 J; rectilinear-1, 0.34 +/- 0.01 J; rectilinear-2, 0.33 +/- 0.01 J; and truncated exponential, 0.32 +/- 0.02 J. Using optically recorded transmembrane responses, we determined the shock-response transfer function, which allowed us to predict the cellular response to waveforms at high accuracy. The passive parallel resistor-capacitor model (RC-model) predicted polarization superiority of the Gurvich waveform in the myocardium with a membrane time constant (taum) of less than 2 ms. The finding of a lower defibrillation threshold with the Gurvich waveform in an in vitro model of external defibrillation suggests that the Gurvich waveform may be important for future external defibrillator designs.
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Affiliation(s)
- Fujian Qu
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
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Israel CW, Grönefeld G. [Technical requirements for early defibrillation: what are the capabilities of automated external defibrillators]. Herzschrittmacherther Elektrophysiol 2005; 16:84-93. [PMID: 15997355 DOI: 10.1007/s00399-005-0468-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2005] [Accepted: 06/09/2005] [Indexed: 11/30/2022]
Abstract
Modern automated external defibrillators (AEDs) offer a variety of technical improvements which increase the efficacy of early defibrillation, facilitate the application by not or minimally trained persons and improve safety. The development of biphasic shocks allows better myocardial protection, the use of lithium batteries, and a marked decrease of AEDs, in size. Microprocessors realize complex acoustic and visual prompts which lead the user through all steps of cardiopulmonary resuscitation (CPR) according to current guidelines. The design of AEDs has been simplified; many devices provide only a single button which can be used for all active processes. Memory functions record the whole CPR with all details which can be transferred to other computers and analyzed off-line. The introduction of AEDs has reduced the delay between collapse and defibrillation to less than 4 min in several studies thus increasing the success of CPR and the proportion of patients dismissed from hospital alive and without neurological deficit. Up to 93% of untrained volunteers were able to successfully complete defibrillation with the use of an AED, sixth-form pupils without experience in CPR were only few sec slower with an AED than staff of emergency medical services. The ability to perform CPR after defibrillation guided by the AED depends primarily on the clarity of acoustic prompts which have to consider the terms and abbreviations of the respective language. Currently available AEDs surpass performance goals of the AHA. However, all devices exhibit advantages and disadvantages which will be discussed in this review.
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Affiliation(s)
- C W Israel
- J. W. Goethe Universitätsklinik, Medizinische Klinik III-Kardiologie, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany.
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Ambler JJS, Zideman DA, Deakin CD. The effect of prophylactic topical steroid cream on the incidence and severity of cutaneous burns following external DC cardioversion. Resuscitation 2005; 65:179-84. [PMID: 15866398 DOI: 10.1016/j.resuscitation.2004.11.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2004] [Accepted: 11/11/2004] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Cutaneous burns are a common cause of morbidity following direct current (DC) cardioversion. We designed a prospective double-blinded controlled study to determine whether the application of steroid cream prior to cardioversion reduces their incidence and severity. MATERIALS AND METHODS Two hours before elective DC cardioversion, we applied betamethasone 0.1% cream or placebo cream over sternal and apical pad sites in 56 patients, with patients acting as their own controls. Two hours after cardioversion, a separate blinded observer measured the visual analogue pain score (VAS), sensory and pain detection thresholds, skin temperature and erythema index at sternal and apical pad sites. RESULTS The study had an 80% power to detect a 50% difference in VAS at 2 h, accepting an alpha error of 0.05. There was no difference between pain at 2 or 24 h, skin temperature, erythema index, sensory and pain detection thresholds at pad sites treated with steroid cream or control. CONCLUSION Topical betamethasone 0.1% cream applied 2 h before elective DC cardioversion is no more effective than placebo at reducing the pain and inflammation from cardioversion burns.
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Affiliation(s)
- Jonathan J S Ambler
- Shackleton Department of Anaesthetics, Southampton University Hospitals NHS Trust, Tremona Road, Southampton SO16 6YD, UK.
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Graham-Garcia J, Heath J, Andrews J. Defibrillation and biphasic shocks: Implications for perianesthesia nursing. J Perianesth Nurs 2005; 20:23-34. [PMID: 15688332 DOI: 10.1016/j.jopan.2004.11.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Cardiac arrests, the majority of which are due to ventricular fibrillation (VF), are a significant threat to survival. The definitive therapy for cardiac arrests due to VF is rapid, early defibrillation. There have been several advances made to modern defibrillators to electively or emergently terminate lethal and nonlethal arrhythmias through external defibrillation. The most recent improvement is in the efficacy of the delivered shock. Biphasic shock waveforms have been shown to be superior to monophasic shocks and are recognized in the current Advanced Cardiac Life Support guidelines by the American Heart Association. Because hospitals are increasingly replacing older models of monophasic capability defibrillators with the newer biphasic capability models, it will be essential for perianesthesia nurses to understand the principles of biphasic technology.
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Gurevitz OT, Ammash NM, Malouf JF, Chandrasekaran K, Rosales AG, Ballman KV, Hammill SC, White RD, Gersh BJ, Friedman PA. Comparative efficacy of monophasic and biphasic waveforms for transthoracic cardioversion of atrial fibrillation and atrial flutter. Am Heart J 2005; 149:316-21. [PMID: 15846271 DOI: 10.1016/j.ahj.2004.07.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND Transthoracic cardioversion fails to restore sinus rhythm in 6% to 33% of patients with atrial fibrillation. This study sought to determine the relative efficacy of biphasic waveforms compared with monophasic waveforms in the treatment of atrial arrhythmias. METHODS A total of 912 patients underwent 1022 transthoracic cardioversions between May 2000 and December 2001. A monophasic damped sine waveform was used in the first 304 cases, and a rectilinear biphasic defibrillator was used in the next 718 cases. RESULTS Use of a biphasic waveform was associated with 94% success in conversion to sinus rhythm compared with 84% with a monophasic waveform (P < .001). The cumulative energy required to restore sinus rhythm was lower with biphasic shocks in both atrial fibrillation and atrial flutter groups (554 +/- 413 J for monophasic vs 199 +/- 216 J for biphasic shocks in the atrial fibrillation group, P < .001; 251 +/- 302 J vs 108 +/- 184 J, respectively, in the atrial flutter group, P < .001). In a multivariate analysis, use of a biphasic shock was associated with a 3.9-fold increase in success of cardioversion. CONCLUSION When used to cardiovert atrial arrhythmias, the rectilinear biphasic waveform was associated with higher success rates and lower cumulative energies than the monophasic damped sine waveform.
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Affiliation(s)
- Osnat T Gurevitz
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN 55905, USA
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Atkins DL, Kenney MA. Automated external defibrillators: safety and efficacy in children and adolescents. Pediatr Clin North Am 2004; 51:1443-62. [PMID: 15331293 DOI: 10.1016/j.pcl.2004.04.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Although children do not suffer from ventricular fibrillation (VF) as frequently as adults, it does occur in 10% to 20% of pediatric cardiac arrests. The technology is available to recognize and treat ventricular fibrillation in children as quickly as we can for adults. This article discusses the evidence to support automated external defibrillator use in young children. As this technology gains increased acceptance, resuscitation rates and outcomes for VF in children should approach those that are seen in adults.
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Affiliation(s)
- Dianne L Atkins
- Division of Pediatric Cardiology, Roy J. and Lucille A. Carver College of Medicine, 200 Hawkins Drive, University of Iowa, Iowa City, IA 52242, USA.
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Zafari AM, Zarter SK, Heggen V, Wilson P, Taylor RA, Reddy K, Backscheider AG, Dudley SC. A program encouraging early defibrillation results in improved in-hospital resuscitation efficacy. J Am Coll Cardiol 2004; 44:846-52. [PMID: 15312869 DOI: 10.1016/j.jacc.2004.04.054] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2004] [Revised: 03/25/2004] [Accepted: 04/06/2004] [Indexed: 01/22/2023]
Abstract
OBJECTIVES The purpose of this study was to determine whether survival to discharge after in-hospital cardiopulmonary arrest could be improved by a program encouraging early defibrillation that included switching from monophasic to biphasic devices. BACKGROUND In-hospital resuscitation continues to have a low success rate. Biphasic waveform devices have demonstrated characteristics that might improve survival, and outside the hospital, automated external defibrillators (AEDs) have shown promise in improving survival of patients suffering cardiopulmonary arrest. METHODS A program including education and replacement of all manual monophasic defibrillators with a combination of manual biphasic defibrillators used in AED mode and AEDs in all outpatient clinics and chronic care units was implemented. RESULTS With program implementation, the percentage survival of all patients with resuscitation events improved 2.6-fold, from 4.9% to 12.8%. Factors independently predicting survival included event location outside an intensive care unit, younger age, an initial rhythm of pulseless ventricular tachycardia (VT) or ventricular fibrillation (VF), pre-arrest beta-blocker, and program initiation. The outcome was independent of gender, race, work shift, number of previous resuscitation attempts, body mass index, comorbidity index, presence of diabetes, presence of hypertension, or use of angiotensin-converting enzyme inhibitors. The improvement in mortality was attributable solely to an effect on patients presenting with VT/VF. Patients with these initial rhythms were 14-fold (odds ratio = 0.07 of death, confidence interval = 0.02 to 0.3) more likely to survive to discharge after program initiation. Automated external defibrillators performed similarly to biphasic manual defibrillators in AED mode. CONCLUSIONS A program including education and use of biphasic manual defibrillators in AED mode and selective use of AEDs improved survival to discharge in hospitalized patients suffering from cardiopulmonary arrest.
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Affiliation(s)
- A Maziar Zafari
- Emory University School of Medicine, Department of Medicine, Division of Cardiology, Atlanta, Georgia, USA
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Ambler JJS, Sado DM, Zideman DA, Deakin CD. The incidence and severity of cutaneous burns following external DC cardioversion. Resuscitation 2004; 61:281-8. [PMID: 15172706 DOI: 10.1016/j.resuscitation.2004.01.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2003] [Revised: 01/04/2004] [Accepted: 01/12/2004] [Indexed: 10/26/2022]
Abstract
INTRODUCTION Cutaneous burns are a common cause of morbidity following direct current (DC) cardioversion, but the incidence and severity have never been quantified. MATERIALS AND METHODS Two hours after elective DC cardioversion in 83 sequential patients, we measured skin temperature, erythema index, and minimum sensory and pain detection thresholds at paddle sites and control sites on the contralateral side. Visual analogue pain score (VAS) was recorded at 2 and 24h post-cardioversion. RESULTS Values for areas over paddle sites were higher (P < 0.05) than control site for all variables measured at 2h. Eighty-four percent patients experienced some pain and 23% patients experienced moderate to severe pain as assessed by VAS. Burns were greater at the edge than the centre of sternal sites and greater at sternal than apical sites. There were positive correlations between transthoracic impedance (TTI) and total energy delivered (r(2) = 0.048; P = 0.04); total energy and pain at 2 h (r(2) = 0.38; P < 0.0001) and 24 h (r(2) = 0.23; P < 0.0001); and number of shocks and pain at 2 h (r(2) = 0.36; P < 0.0001) and 24 h (r(2) = 0.19; P < 0.0001). CONCLUSION Elective DC cardioversion causes burns as measured by skin temperature, erythema index and sensory threshold to sharp touch. Pain experienced is related to the total energy and number of shocks delivered. To reduce burns, operators should apply optimal paddle force equally to both paddles, with the paddles applied so as to provide even contact along their edges. Burns may also be minimised by starting with lower energy shocks.
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Affiliation(s)
- Jonathan J S Ambler
- Shackleton Department of Anaesthetics, Southampton University Hospitals NHS Trust, Tremona Road, Southampton SO16 6YD, UK
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Tang W, Weil MH, Sun S, Jorgenson D, Morgan C, Klouche K, Snyder D. The effects of biphasic waveform design on post-resuscitation myocardial function. J Am Coll Cardiol 2004; 43:1228-35. [PMID: 15063435 DOI: 10.1016/j.jacc.2003.10.055] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2003] [Revised: 10/14/2003] [Accepted: 10/20/2003] [Indexed: 11/18/2022]
Abstract
OBJECTIVES This study examined the effects of biphasic truncated exponential waveform design on survival and post-resuscitation myocardial function after prolonged ventricular fibrillation (VF). BACKGROUND Biphasic waveforms are more effective than monophasic waveforms for successful defibrillation, but optimization of energy and current levels to minimize post-resuscitation myocardial dysfunction has been largely unexplored. We examined a low-capacitance waveform typical of low-energy application (low-energy biphasic truncated exponential [BTEL]; 100 microF, < or =200 J) and a high-capacitance waveform typical of high-energy application (high-energy biphasic truncated exponential [BTEH]; 200 microF, > or =200 J). METHODS Four groups of anesthetized 40- to 45-kg pigs were investigated. After 7 min of electrically induced VF, a 15-min resuscitation attempt was made using sequences of up to three defibrillation shocks followed by 1 min of cardiopulmonary resuscitation. Animals were randomized to BTEL at 150 J or 200 J or to BTEH at 200 J or 360 J. RESULTS Resuscitation was unsuccessful in three of the five animals treated with BTEH at 200 J. All other attempts were successful. Significant therapy effects were observed for survival (p = 0.035), left ventricular ejection fraction (p < 0.001), stroke volume (p < 0.001), fractional area change (p < 0.001), cardiac output (p = 0.044), and mean aortic pressure (p < 0.001). Hemodynamic outcomes were negatively associated with energy and average current but positively associated with peak current. Peak current was the only significant predictor of survival (p < 0.001). CONCLUSIONS Maximum survival and minimum myocardial dysfunction were observed with the low-capacitance 150-J waveform, which delivered higher peak current while minimizing energy and average current.
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Affiliation(s)
- Wanchun Tang
- Insitute of Critical Care Medicine, Palm Springs, California 92262-5309, USA.
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Lischke V, Kessler P, Byhahn C, Westphal K, Amann A. [Transthoracic defibrillation. Physiologic and pathophysiologic principles and their role in the outcome of resuscitation]. Anaesthesist 2004; 53:125-36. [PMID: 14991189 DOI: 10.1007/s00101-003-0635-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
As one major link in the chain of survival, early transthoracic (external) cardiac defibrillation is aimed at the termination of ventricular flutter and ventricular fibrillation. Most important to the success of defibrillation is the passage of a defined amount of current through a critical mass of heart muscle. Different transthoracic resistances reduce the effective density of the current within the heart. As for other therapeutic intervention procedures, recommendations for the optimal strength of current to be applied to the fibrillating heart need to be evaluated and defined for therapeutical defibrillation too. Unnecessarily high current density causes damage to the heart and should be prevented. By using biphasic waveforms in contrast to monophasic impulses, the amount of current can be reduced but the same or even higher efficacy is attained. Therefore possible myocardial damage might be clearly reduced. Even with individually altered thoracic impedance effective conversion of cardiac rhythm can be achieved by device-controlled compensation and biphasic waveforms. According to their different mechanisms or origin (electrically induced or spontaneously caused by organic heart disease) the probability of successful conversion of the cardiac rhythm by one single electrical impulse varies. The optimum point in time for defibrillation during resuscitation needs to be redefined. In order to improve comparability, further studies should use standardized definitions for successful defibrillation relating to the resulting cardiac rhythm.
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Affiliation(s)
- V Lischke
- Anästhesie-Abteilung und operative Intensivmedizin, Hochtaunus-Kliniken gGmbH, Bad Homburg.
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Reek S, Geller JC, Meltendorf U, Wollbrueck A, Szymkiewicz SJ, Klein HU. Clinical efficacy of a wearable defibrillator in acutely terminating episodes of ventricular fibrillation using biphasic shocks. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2004; 26:2016-22. [PMID: 14516344 DOI: 10.1046/j.1460-9592.2003.00311.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Wearable Cardioverter Defibrillator (WCD) automatically detects and treats ventricular tachyarrhythmias without the need for assistance from a bystander, while at the same time allowing the patient to ambulate freely. It represents an alternative to emergency medical services for outpatient populations with a temporary risk of sudden cardiac death. While the original devices used a monophasic truncated exponential waveform for cardioversion/defibrillation shocks, a new, biphasic shock was developed for the next device generation. In 12 patients undergoing electrophysiological testing for ventricular tachyarrhythmias, termination of electrically induced ventricular fibrillation (VF) was attempted via the WCD. In 22 episodes, induced VF was promptly terminated by the first 70 J (n=12) or 100 J (n=10) biphasic shocks. Time between arrhythmia initiation and shock delivery was 22 +/- 6 seconds (70 J) and 21 +/- 6 seconds (100 J) (P=NS). The measured transthoracic impedance was 71 +/- 5 Ohms (64-79 Ohms) for the 70 J shock and 64 +/- 8 Ohms (47-72 Ohms) for the 100 J shock. The present study demonstrates that a single low energy biphasic shock delivered by the WCD, reliably terminates electrically induced VF (100% of episodes). The results of this study suggest that there is an acceptable safety margin to the maximum output of the device (150 J). Despite our promising data, we recommend that programming all shocks for maximum energy output should be done when using the WCD in ambulatory patients.
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Affiliation(s)
- Sven Reek
- Division of Cardiology, University Hospital Magdeburg, Germany.
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Higgins SL, O'Grady SG, Banville I, Chapman FW, Schmitt PW, Lank P, Walker RG, Ilina M. E FFICACY OFL OWER-ENERGYB IPHASICS HOCKS FORT RANSTHORACICD EFIBRILLATION: A F OLLOW-UPC LINICALS TUDY. PREHOSP EMERG CARE 2004. [DOI: 10.1080/312704000188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Yamanouchi Y, Mowrey K, Mazgalev TN, Wilkoff BL, Tchou PJ. The Strength-Duration Relationship of Monophasic Waveforms with Varying Capacitance Sizes in External Defibrillation. Pacing Clin Electrophysiol 2003; 26:2213-8. [PMID: 14675002 DOI: 10.1111/j.1540-8159.2003.00349.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The shape of the shock waveform influences defibrillation efficacy. However, the optimal combination between capacitance size and truncation/tilt which can determine monophasic waveform's shape, has not been determined for external defibrillation. The purpose of this study was to assess the effects of varying capacitance and tilt on external defibrillation using exponential monophasic waveforms. In a pig model of external defibrillation (n = 10, 30 +/- 6 kg), nine exponential monophasic waveforms combining three capacitance values (30 microF, 60 microF, and 120 microF) and three tilt values (55%, 75%, and 95%) were tested randomly. The energy and leading edge voltage at 50% defibrillation success (E50 and V50) were used to evaluate defibrillation efficacy. E50 and V50 were determined by the Bayesian technique. The lowest stored E50 for the 30microF, 60 microF, and 120 microF waveforms were 90 +/- 12 J (95% tilt), 106 +/- 45 J (55% tilt), and 107 +/- 52 J (75% tilt), respectively. The lowest V50 for the 30 microF, 60 microF, and 120 microF waveforms were 2,439 +/- 166 V (95% tilt), 1,849 +/- 375 V (55% tilt), and 1,301 +/- 322 V (75% tilt), respectively. The average current at external defibrillation threshold demonstrated a strength versus pulse duration relationship similar to that seen with pacing. Reducing capacitance has the same effect as truncating the waveform. The E50 is more sensitive to tilt values changes in larger capacitance waveforms. This study suggests that the optimal combination between capacitance and tilt may be 120 microF and 55%-75% for external defibrillation.
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Affiliation(s)
- Yoshio Yamanouchi
- Department of Cardiology, Cleveland Clinic Foundation, Cleveland, Ohio, USA.
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Carpenter J, Rea TD, Murray JA, Kudenchuk PJ, Eisenberg MS. Defibrillation waveform and post-shock rhythm in out-of-hospital ventricular fibrillation cardiac arrest. Resuscitation 2003; 59:189-96. [PMID: 14625109 DOI: 10.1016/s0300-9572(03)00183-7] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The importance of the defibrillation waveform on the evolving post-shock cardiac rhythm is uncertain. The primary objective of this study was to evaluate cardiac rhythms following the first defibrillation shock, comparing biphasic truncated exponential (BTE), monophasic damped sinusoidal (MDS), and monophasic truncated exponential (MTE) waveforms in patients experiencing out-of-hospital ventricular fibrillation cardiac arrest (OHCA). METHODS We reviewed the automated external defibrillator (AED) and emergency medical services (EMS) records of 366 patients who suffered OHCA and were treated with defibrillation shocks by first-tier emergency responders between 1 January 1999 and 31 August 2002 in King County, Washington. The post first shock rhythms were determined at 5, 10, 20, 30, and 60 s and compared according to defibrillation waveform. RESULTS The MDS and BTE waveforms were associated with significantly higher frequency of defibrillation than the MTE waveform, though only the BTE association persisted to 30 and 60 s. No difference in defibrillation rates was detected between MDS and BTE waveforms. By 60 s, an organized rhythm was present in a greater proportion for BTE (40.0%) compared with MDS (25.4%, P=0.01) or MTE (26.5%, P=0.07). CONCLUSION In this retrospective cohort investigation, MDS and BTE waveforms had higher first shock defibrillation rates than the MTE waveform, while patients treated with the BTE waveform were more likely to develop an organized rhythm within 60 s of the initial shock. The results of this investigation, however, do not provide evidence that these surrogate advantages are important for improving survival. Additional investigation is needed to improve the understanding of the role of waveform and its potential interaction with other clinical factors in order to optimize survival in OHCA.
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Affiliation(s)
- John Carpenter
- Emergency Medical Services Division, Public Health, Seattle, King County, 999 Third Avenue, Suite 700, Seattle, WA 98104-4039, USA
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van Alem AP, Post J, Koster RW. VF recurrence: characteristics and patient outcome in out-of-hospital cardiac arrest. Resuscitation 2003; 59:181-8. [PMID: 14625108 DOI: 10.1016/s0300-9572(03)00208-9] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND Refibrillation after successful defibrillation in out-of-hospital cardiac arrest is a frequent event. Little is known of factors that predispose to the occurrence of refibrillation. The effect of recurrence of ventricular fibrillation (VF) on survival is not known. METHODS Data of patients in out-of-hospital cardiac arrest were collected in a combined first responder and paramedic programme in Amsterdam, the Netherlands. Continuous recorded rhythm data of 322 patients covering the entire out-of-hospital resuscitation attempt was included in the analysis. Recurrence of VF was recorded, the patient and process characteristics were analysed in relation to the occurrence of refibrillation. The number of refibrillations was related to survival. RESULTS AND CONCLUSION Of the studied patients 79% had at least one recurrence of VF, and a median number of two times 25-75%; one to four times). The median time from successful first shock to VF recurrence was 45 s (25-75%: 23-115 s). A significant inverse relation was found between the number of refibrillations and survival of out-of-hospital cardiac arrest. The recurrence of VF was independent of the underlying cardiac disorder, the time to defibrillation, the defibrillation waveform and other characteristics of the patient and the process. Anti-arrhythmics should be considered in all patients found in VF to reduce the number of recurrences.
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Affiliation(s)
- Anouk P van Alem
- Department of Cardiology, Academic Medical Centre, room B2-239, Meibergdreef 9, 1105 AZ Amsterdam, Netherlands.
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Walcott GP, Killingsworth CR, Ideker RE. Do clinically relevant transthoracic defibrillation energies cause myocardial damage and dysfunction? Resuscitation 2003; 59:59-70. [PMID: 14580735 DOI: 10.1016/s0300-9572(03)00161-8] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Sufficiently strong defibrillation shocks will cause temporary or permanent damage to the heart. Weak defibrillation shocks do not cause any damage to the heart but also do not defibrillate. A relevant and practical question is what range of shock energies is most likely to defibrillate while not causing damage to the heart. This question is most difficult to answer in the pre-hospital defibrillation setting where the patients' size and shape vary, placement of the defibrillation patches vary, and the etiology of their arrhythmia varies. Unlike internal defibrillators, which are tested at implantation, efficacy of an external defibrillator is determined only once, when it is most needed. This review discusses shock damage and dysfunction caused by monophasic waveforms as well as biphasic waveforms. Evidence is presented suggesting that for perfused hearts, the threshold for damage is well above any shock size delivered clinically. For non-perfused hearts, both in humans and animals, evidence is presented that monophasic shocks of up to 5 J/kg do not cause any more cardiac damage/dysfunction than that associated with smaller shocks and that much of this damage is caused by the ischemic period itself rather than the shock. Although many patients can be defibrillated with 150 J (2.2 J/kg) biphasic shocks, some patients may require biphasic shocks up to 360 J (5 J/kg) to be defibrillated. Studies still need to be performed comparing the efficacy and damaging effects of 360 J biphasic shocks to 150 J biphasic shocks. Until those studies are completed, it seems reasonable to use the same 360 J (5 J/kg) energy limit for biphasic shocks as for monophasic shocks.
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Affiliation(s)
- Gregory P Walcott
- Cardiac Rhythm Management Laboratory, Division of Cardiovascular Diseases, Department of Medicine, University of Alabama at Birmingham, Volker Hall B140, 1670 University Blvd., Birmingham, AL 35294, USA.
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Scholten M, Szili-Torok T, Klootwijk P, Jordaens L. Comparison of monophasic and biphasic shocks for transthoracic cardioversion of atrial fibrillation. Heart 2003; 89:1032-4. [PMID: 12923020 PMCID: PMC1767835 DOI: 10.1136/heart.89.9.1032] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
OBJECTIVE To compare the efficacy of cardioversion in patients with atrial fibrillation between monophasic damped sine waveform and rectilinear biphasic waveform shocks at a high initial energy level and with a conventional paddle position. DESIGN Prospective randomised study. PATIENTS AND SETTING 227 patients admitted for cardioversion of atrial fibrillation to a tertiary referral centre. RESULTS 70% of 109 patients treated with an initial 200 J monophasic shock were cardioverted to sinus rhythm, compared with 80% of 118 patients treated with an initial 120 J biphasic shock (NS). After the second shock (360 J monophasic or 200 J biphasic), 90% of the patients were in sinus rhythm in both groups. The mean cumulative energy used for successful cardioversion was 306 J for monophasic shocks and 159 J for biphasic shocks (p < 0.001). CONCLUSIONS A protocol using monophasic waveform shocks in a 200-360 J sequence has the same efficacy (90%) as a protocol using rectilinear biphasic waveform shocks in a 120-200 J sequence. This equal efficacy is achieved with a significantly lower mean delivered energy level using the rectilinear biphasic shock waveform. The potential advantage of lower energy delivery for cardioversion of atrial fibrillation needs further study.
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Affiliation(s)
- M Scholten
- Erasmus University Medical Centre, Thoraxcentre, Department of Clinical Electrophysiology, Rotterdam, Netherlands.
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Zhang Y, Ramabadran RS, Boddicker KA, Bawaney I, Davies LR, Zimmerman MB, Wuthrich S, Jones JL, Kerber RE. Triphasic waveforms are superior to biphasic waveforms for transthoracic defibrillation: experimental studies. J Am Coll Cardiol 2003; 42:568-75. [PMID: 12906990 DOI: 10.1016/s0735-1097(03)00656-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
OBJECTIVES Our objective was to evaluate the efficacy of triphasic waveforms for transthoracic defibrillation in a swine model. BACKGROUND Triphasic shocks have been found to cause less post-shock dysfunction than biphasic shocks in chick embryo studies. METHODS After 30 s of electrically induced ventricular fibrillation (VF), each pig in part I (n = 32) received truncated exponential biphasic (7.2/7.2 ms) and triphasic (4.8/4.8/4.8 ms) transthoracic shocks. Each pig in part II (n = 14) received biphasic (5/5 ms) and triphasic shocks (5/5/5 ms). Three selected energy levels (50, 100, and 150 J) were tested for parts I and II. Pigs in part III (n = 13) received biphasic (5/5 ms) and triphasic (5/5/5 ms) shocks at a higher energy (200 and 300 J). Although the individual pulse durations of these shocks were equal, the energy of each pulse varied. Nine pigs in part I also received shocks where each individual pulse contained equal energy but was of a different duration (biphasic 3.3/11.1 ms; triphasic 2.0/3.2/9.2 ms). RESULTS Triphasic shocks of equal duration pulses achieved higher success than biphasic shocks at delivered low energies: <40 J: 38 +/- 5% triphasic vs. 19 +/- 4% biphasic (p < 0.01); 40 to <50 J: 66 +/- 7% vs. 42 +/- 7% (p < 0.01); and 50 to <65 J: 78 +/- 4% vs. 54 +/- 5% (p < 0.05). Shocks of equal energy but different duration pulses achieved relatively poor success for both triphasic and biphasic waveforms. Shock-induced ventricular tachycardia (VT) and asystole occurred less often after triphasic shocks. CONCLUSIONS Triphasic transthoracic shocks composed of equal duration pulses were superior to biphasic shocks for VF termination at low energies and caused less VT and asystole.
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Affiliation(s)
- Yi Zhang
- Cardiovascular Center, College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA
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