1
|
Katzenschlager S, Obermaier M, Kuhner M, Spöttl W, Dietrich M, Weigand MA, Weilbacher F, Popp E. [Focus emergency medicine 2022/2023-Summary of selected studies in emergency medicine]. DIE ANAESTHESIOLOGIE 2023; 72:809-820. [PMID: 37725144 DOI: 10.1007/s00101-023-01330-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/02/2023] [Indexed: 09/21/2023]
Affiliation(s)
- S Katzenschlager
- Klinik für Anästhesiologie, Universitätsklinikum Heidelberg, Heidelberg, Deutschland.
| | - M Obermaier
- Klinik für Anästhesiologie, Universitätsklinikum Heidelberg, Heidelberg, Deutschland
| | - M Kuhner
- Klinik für Intensivmedizin, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Deutschland
| | - W Spöttl
- Klinik für Anästhesiologie, Universitätsklinikum Heidelberg, Heidelberg, Deutschland
| | - M Dietrich
- Klinik für Anästhesiologie, Universitätsklinikum Heidelberg, Heidelberg, Deutschland
| | - M A Weigand
- Klinik für Anästhesiologie, Universitätsklinikum Heidelberg, Heidelberg, Deutschland
| | - F Weilbacher
- Klinik für Anästhesiologie, Universitätsklinikum Heidelberg, Heidelberg, Deutschland
| | - E Popp
- Klinik für Anästhesiologie, Universitätsklinikum Heidelberg, Heidelberg, Deutschland
| |
Collapse
|
2
|
Okada JI, Washio T, Sugiura S, Hisada T. Low-energy defibrillation using a base-apex epicardial electrode. Pacing Clin Electrophysiol 2023; 46:1325-1332. [PMID: 37830313 DOI: 10.1111/pace.14832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 08/17/2023] [Accepted: 09/10/2023] [Indexed: 10/14/2023]
Abstract
BACKGROUND Current implantable cardioverter defibrillators (ICDs) require electric conduction with high voltage and high energy, which can impair cardiac function and induce another malignant arrhythmia. As a result, there has been a demand for an ICD that can effectively operate with lower energy to mitigate the risks of a strong electric shock. METHODS A pair of sheet-shaped electrodes covering the heart were analyzed in three configurations (top-bottom, left-right, and front-back) using a heart simulator. We also varied the distance between the two electrodes (clearance) to identify the electrode shape with the lowest defibrillation threshold (DFT). We also investigated the ICD shock waveform, shock direction, and the effect of the backside insulator of the electrode. RESULTS The DFT was high when the clearance was too small and the DFT was high even when the clearance was too large, suggesting that an optimal value clearance. The top-bottom electrodes with optimal clearance showed the lowest DFT when the biphasic shocks set the top electrode to a high potential first and then the bottom electrode was set to a high potential. An interval between a first shock waveform and a second shock waveform should be provided for low-energy defibrillation. Because the insulator prevents unnecessary current flow to the backside, the DFT of the electrodes with insulators is less than those without insulators. CONCLUSION Painless defibrillation using sheet-shaped electrodes on the epicardium is predicated on the basis of results using a heart simulator.
Collapse
Affiliation(s)
- Jun-Ichi Okada
- UT-Heart Inc., Setagaya-ku, Tokyo, Japan
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa-shi, Chiba, Japan
| | - Takumi Washio
- UT-Heart Inc., Setagaya-ku, Tokyo, Japan
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa-shi, Chiba, Japan
| | | | | |
Collapse
|
3
|
Abuelazm MT, Ghanem A, Katamesh BE, Hassan AR, Abdalshafy H, Seri AR, Awad AK, Abdelnabi M, Abdelazeem B. Defibrillation strategies for refractory ventricular fibrillation out-of-hospital cardiac arrest: A systematic review and network meta-analysis. Ann Noninvasive Electrocardiol 2023; 28:e13075. [PMID: 37482919 PMCID: PMC10475889 DOI: 10.1111/anec.13075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 06/10/2023] [Accepted: 07/10/2023] [Indexed: 07/25/2023] Open
Abstract
BACKGROUND AND OBJECTIVE Double sequential external defibrillation (DSED) and vector-change defibrillation (VCD) have been suggested to enhance clinical outcomes for patients with ventricular fibrillation (VF) refractory of standard defibrillation (SD). Therefore, this network meta-analysis aims to evaluate the comparative efficacy of DSED, VCD, and SD for refractory VF. METHODS A systematic review and network meta-analysis synthesizing randomized controlled trials (RCTs) and comparative observational studies retrieved from PubMed, EMBASE, WOS, SCOPUS, and Cochrane through November 15th, 2022. R software netmeta and netrank package (R version 4.2.0) and meta-insight software were used to pool dichotomous outcomes using odds ratio (OR) presented with the corresponding confidence interval (CI). Our protocol was prospectively published in PROSPERO with ID: CRD42022378533. RESULTS We included seven studies with a total of 1632 participants. DSED was similar to SD in survival to hospital discharge (OR: 1.14 with 95% CI [0.55, 2.83]), favorable neurological outcome (modified Rankin scale ≤2 or cerebral performance category ≤2) (OR: 1.35 with 95% CI [0.46, 3.99]), and return of spontaneous circulation (ROSC) (OR: 0.81 with 95% CI [0.43; 1.5]). In addition, VCD was similar to SD in survival to hospital discharge (OR: 1.12 with 95% CI [0.27, 4.57]), favorable neurological outcome (OR: 1.01 with 95% CI [0.18, 5.75]), and ROSC (OR: 0.88 with 95% CI [0.24; 3.15]). CONCLUSION Double sequential external defibrillation and VCD were not associated with enhanced outcomes in patients with refractory VF out-of-hospital cardiac arrest, compared to SD. However, the current evidence is still inconclusive, warranting further large-scale RCTs.
Collapse
Affiliation(s)
| | - Ahmed Ghanem
- Cardiology DepartmentThe Lundquist InstituteTorranceCaliforniaUSA
| | | | | | | | - Amith Reddy Seri
- Department of Internal MedicineMcLaren Health CareFlintMichiganUSA
- Department of Internal MedicineMichigan State UniversityEast LansingMichiganUSA
| | | | - Mohamed Abdelnabi
- Department of Clinical PharmacyUniversity of MichiganAnn ArborMichiganUSA
| | - Basel Abdelazeem
- Department of Internal MedicineMcLaren Health CareFlintMichiganUSA
- Department of Internal MedicineMichigan State UniversityEast LansingMichiganUSA
| |
Collapse
|
4
|
Double sequential external defibrillation for refractory ventricular fibrillation. Intensive Care Med 2023; 49:455-457. [PMID: 36754880 PMCID: PMC9907872 DOI: 10.1007/s00134-023-06993-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 01/21/2023] [Indexed: 02/10/2023]
|
5
|
Cheskes S, Verbeek PR, Drennan IR, McLeod SL, Turner L, Pinto R, Feldman M, Davis M, Vaillancourt C, Morrison LJ, Dorian P, Scales DC. Defibrillation Strategies for Refractory Ventricular Fibrillation. N Engl J Med 2022; 387:1947-1956. [PMID: 36342151 DOI: 10.1056/nejmoa2207304] [Citation(s) in RCA: 60] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Despite advances in defibrillation technology, shock-refractory ventricular fibrillation remains common during out-of-hospital cardiac arrest. Double sequential external defibrillation (DSED; rapid sequential shocks from two defibrillators) and vector-change (VC) defibrillation (switching defibrillation pads to an anterior-posterior position) have been proposed as defibrillation strategies to improve outcomes in patients with refractory ventricular fibrillation. METHODS We conducted a cluster-randomized trial with crossover among six Canadian paramedic services to evaluate DSED and VC defibrillation as compared with standard defibrillation in adult patients with refractory ventricular fibrillation during out-of-hospital cardiac arrest. Patients were treated with one of these three techniques according to the strategy that was randomly assigned to the paramedic service. The primary outcome was survival to hospital discharge. Secondary outcomes included termination of ventricular fibrillation, return of spontaneous circulation, and a good neurologic outcome, defined as a modified Rankin scale score of 2 or lower (indicating no symptoms to slight disability) at hospital discharge. RESULTS A total of 405 patients were enrolled before the data and safety monitoring board stopped the trial because of the coronavirus disease 2019 pandemic. A total of 136 patients (33.6%) were assigned to receive standard defibrillation, 144 (35.6%) to receive VC defibrillation, and 125 (30.9%) to receive DSED. Survival to hospital discharge was more common in the DSED group than in the standard group (30.4% vs. 13.3%; relative risk, 2.21; 95% confidence interval [CI], 1.33 to 3.67) and more common in the VC group than in the standard group (21.7% vs. 13.3%; relative risk, 1.71; 95% CI, 1.01 to 2.88). DSED but not VC defibrillation was associated with a higher percentage of patients having a good neurologic outcome than standard defibrillation (relative risk, 2.21 [95% CI, 1.26 to 3.88] and 1.48 [95% CI, 0.81 to 2.71], respectively). CONCLUSIONS Among patients with refractory ventricular fibrillation, survival to hospital discharge occurred more frequently among those who received DSED or VC defibrillation than among those who received standard defibrillation. (Funded by the Heart and Stroke Foundation of Canada; DOSE VF ClinicalTrials.gov number, NCT04080986.).
Collapse
Affiliation(s)
- Sheldon Cheskes
- From the Division of Emergency Medicine, Department of Family and Community Medicine (S.C., I.R.D., S.L.M.), the Division of Emergency Medicine, Department of Medicine, (P.R.V., L.J.M.), the Interdepartmental Division of Critical Care Medicine (R.P., D.C.S.), and the Department of Medicine (R.P., P.D., D.C.S.), Temerty Faculty of Medicine, University of Toronto, the Sunnybrook Centre for Prehospital Medicine (S.C., P.R.V., L.T., M.F.), the Departments of Emergency Services (I.R.D., L.J.M.) and Critical Care Medicine (R.P., D.C.S.), Sunnybrook Health Sciences Centre, the Schwartz/Reisman Emergency Medicine Institute, Sinai Health (S.L.M.), and the Division of Cardiology, Unity Health Toronto (P.D.), Toronto, the Division of Emergency Medicine, London Health Sciences Centre, Department of Medicine, University of Western Ontario, London (M.D.), and the Department of Emergency Medicine, Ottawa Hospital Research Institute, Ottawa (C.V.) - all in Canada
| | - P Richard Verbeek
- From the Division of Emergency Medicine, Department of Family and Community Medicine (S.C., I.R.D., S.L.M.), the Division of Emergency Medicine, Department of Medicine, (P.R.V., L.J.M.), the Interdepartmental Division of Critical Care Medicine (R.P., D.C.S.), and the Department of Medicine (R.P., P.D., D.C.S.), Temerty Faculty of Medicine, University of Toronto, the Sunnybrook Centre for Prehospital Medicine (S.C., P.R.V., L.T., M.F.), the Departments of Emergency Services (I.R.D., L.J.M.) and Critical Care Medicine (R.P., D.C.S.), Sunnybrook Health Sciences Centre, the Schwartz/Reisman Emergency Medicine Institute, Sinai Health (S.L.M.), and the Division of Cardiology, Unity Health Toronto (P.D.), Toronto, the Division of Emergency Medicine, London Health Sciences Centre, Department of Medicine, University of Western Ontario, London (M.D.), and the Department of Emergency Medicine, Ottawa Hospital Research Institute, Ottawa (C.V.) - all in Canada
| | - Ian R Drennan
- From the Division of Emergency Medicine, Department of Family and Community Medicine (S.C., I.R.D., S.L.M.), the Division of Emergency Medicine, Department of Medicine, (P.R.V., L.J.M.), the Interdepartmental Division of Critical Care Medicine (R.P., D.C.S.), and the Department of Medicine (R.P., P.D., D.C.S.), Temerty Faculty of Medicine, University of Toronto, the Sunnybrook Centre for Prehospital Medicine (S.C., P.R.V., L.T., M.F.), the Departments of Emergency Services (I.R.D., L.J.M.) and Critical Care Medicine (R.P., D.C.S.), Sunnybrook Health Sciences Centre, the Schwartz/Reisman Emergency Medicine Institute, Sinai Health (S.L.M.), and the Division of Cardiology, Unity Health Toronto (P.D.), Toronto, the Division of Emergency Medicine, London Health Sciences Centre, Department of Medicine, University of Western Ontario, London (M.D.), and the Department of Emergency Medicine, Ottawa Hospital Research Institute, Ottawa (C.V.) - all in Canada
| | - Shelley L McLeod
- From the Division of Emergency Medicine, Department of Family and Community Medicine (S.C., I.R.D., S.L.M.), the Division of Emergency Medicine, Department of Medicine, (P.R.V., L.J.M.), the Interdepartmental Division of Critical Care Medicine (R.P., D.C.S.), and the Department of Medicine (R.P., P.D., D.C.S.), Temerty Faculty of Medicine, University of Toronto, the Sunnybrook Centre for Prehospital Medicine (S.C., P.R.V., L.T., M.F.), the Departments of Emergency Services (I.R.D., L.J.M.) and Critical Care Medicine (R.P., D.C.S.), Sunnybrook Health Sciences Centre, the Schwartz/Reisman Emergency Medicine Institute, Sinai Health (S.L.M.), and the Division of Cardiology, Unity Health Toronto (P.D.), Toronto, the Division of Emergency Medicine, London Health Sciences Centre, Department of Medicine, University of Western Ontario, London (M.D.), and the Department of Emergency Medicine, Ottawa Hospital Research Institute, Ottawa (C.V.) - all in Canada
| | - Linda Turner
- From the Division of Emergency Medicine, Department of Family and Community Medicine (S.C., I.R.D., S.L.M.), the Division of Emergency Medicine, Department of Medicine, (P.R.V., L.J.M.), the Interdepartmental Division of Critical Care Medicine (R.P., D.C.S.), and the Department of Medicine (R.P., P.D., D.C.S.), Temerty Faculty of Medicine, University of Toronto, the Sunnybrook Centre for Prehospital Medicine (S.C., P.R.V., L.T., M.F.), the Departments of Emergency Services (I.R.D., L.J.M.) and Critical Care Medicine (R.P., D.C.S.), Sunnybrook Health Sciences Centre, the Schwartz/Reisman Emergency Medicine Institute, Sinai Health (S.L.M.), and the Division of Cardiology, Unity Health Toronto (P.D.), Toronto, the Division of Emergency Medicine, London Health Sciences Centre, Department of Medicine, University of Western Ontario, London (M.D.), and the Department of Emergency Medicine, Ottawa Hospital Research Institute, Ottawa (C.V.) - all in Canada
| | - Ruxandra Pinto
- From the Division of Emergency Medicine, Department of Family and Community Medicine (S.C., I.R.D., S.L.M.), the Division of Emergency Medicine, Department of Medicine, (P.R.V., L.J.M.), the Interdepartmental Division of Critical Care Medicine (R.P., D.C.S.), and the Department of Medicine (R.P., P.D., D.C.S.), Temerty Faculty of Medicine, University of Toronto, the Sunnybrook Centre for Prehospital Medicine (S.C., P.R.V., L.T., M.F.), the Departments of Emergency Services (I.R.D., L.J.M.) and Critical Care Medicine (R.P., D.C.S.), Sunnybrook Health Sciences Centre, the Schwartz/Reisman Emergency Medicine Institute, Sinai Health (S.L.M.), and the Division of Cardiology, Unity Health Toronto (P.D.), Toronto, the Division of Emergency Medicine, London Health Sciences Centre, Department of Medicine, University of Western Ontario, London (M.D.), and the Department of Emergency Medicine, Ottawa Hospital Research Institute, Ottawa (C.V.) - all in Canada
| | - Michael Feldman
- From the Division of Emergency Medicine, Department of Family and Community Medicine (S.C., I.R.D., S.L.M.), the Division of Emergency Medicine, Department of Medicine, (P.R.V., L.J.M.), the Interdepartmental Division of Critical Care Medicine (R.P., D.C.S.), and the Department of Medicine (R.P., P.D., D.C.S.), Temerty Faculty of Medicine, University of Toronto, the Sunnybrook Centre for Prehospital Medicine (S.C., P.R.V., L.T., M.F.), the Departments of Emergency Services (I.R.D., L.J.M.) and Critical Care Medicine (R.P., D.C.S.), Sunnybrook Health Sciences Centre, the Schwartz/Reisman Emergency Medicine Institute, Sinai Health (S.L.M.), and the Division of Cardiology, Unity Health Toronto (P.D.), Toronto, the Division of Emergency Medicine, London Health Sciences Centre, Department of Medicine, University of Western Ontario, London (M.D.), and the Department of Emergency Medicine, Ottawa Hospital Research Institute, Ottawa (C.V.) - all in Canada
| | - Matthew Davis
- From the Division of Emergency Medicine, Department of Family and Community Medicine (S.C., I.R.D., S.L.M.), the Division of Emergency Medicine, Department of Medicine, (P.R.V., L.J.M.), the Interdepartmental Division of Critical Care Medicine (R.P., D.C.S.), and the Department of Medicine (R.P., P.D., D.C.S.), Temerty Faculty of Medicine, University of Toronto, the Sunnybrook Centre for Prehospital Medicine (S.C., P.R.V., L.T., M.F.), the Departments of Emergency Services (I.R.D., L.J.M.) and Critical Care Medicine (R.P., D.C.S.), Sunnybrook Health Sciences Centre, the Schwartz/Reisman Emergency Medicine Institute, Sinai Health (S.L.M.), and the Division of Cardiology, Unity Health Toronto (P.D.), Toronto, the Division of Emergency Medicine, London Health Sciences Centre, Department of Medicine, University of Western Ontario, London (M.D.), and the Department of Emergency Medicine, Ottawa Hospital Research Institute, Ottawa (C.V.) - all in Canada
| | - Christian Vaillancourt
- From the Division of Emergency Medicine, Department of Family and Community Medicine (S.C., I.R.D., S.L.M.), the Division of Emergency Medicine, Department of Medicine, (P.R.V., L.J.M.), the Interdepartmental Division of Critical Care Medicine (R.P., D.C.S.), and the Department of Medicine (R.P., P.D., D.C.S.), Temerty Faculty of Medicine, University of Toronto, the Sunnybrook Centre for Prehospital Medicine (S.C., P.R.V., L.T., M.F.), the Departments of Emergency Services (I.R.D., L.J.M.) and Critical Care Medicine (R.P., D.C.S.), Sunnybrook Health Sciences Centre, the Schwartz/Reisman Emergency Medicine Institute, Sinai Health (S.L.M.), and the Division of Cardiology, Unity Health Toronto (P.D.), Toronto, the Division of Emergency Medicine, London Health Sciences Centre, Department of Medicine, University of Western Ontario, London (M.D.), and the Department of Emergency Medicine, Ottawa Hospital Research Institute, Ottawa (C.V.) - all in Canada
| | - Laurie J Morrison
- From the Division of Emergency Medicine, Department of Family and Community Medicine (S.C., I.R.D., S.L.M.), the Division of Emergency Medicine, Department of Medicine, (P.R.V., L.J.M.), the Interdepartmental Division of Critical Care Medicine (R.P., D.C.S.), and the Department of Medicine (R.P., P.D., D.C.S.), Temerty Faculty of Medicine, University of Toronto, the Sunnybrook Centre for Prehospital Medicine (S.C., P.R.V., L.T., M.F.), the Departments of Emergency Services (I.R.D., L.J.M.) and Critical Care Medicine (R.P., D.C.S.), Sunnybrook Health Sciences Centre, the Schwartz/Reisman Emergency Medicine Institute, Sinai Health (S.L.M.), and the Division of Cardiology, Unity Health Toronto (P.D.), Toronto, the Division of Emergency Medicine, London Health Sciences Centre, Department of Medicine, University of Western Ontario, London (M.D.), and the Department of Emergency Medicine, Ottawa Hospital Research Institute, Ottawa (C.V.) - all in Canada
| | - Paul Dorian
- From the Division of Emergency Medicine, Department of Family and Community Medicine (S.C., I.R.D., S.L.M.), the Division of Emergency Medicine, Department of Medicine, (P.R.V., L.J.M.), the Interdepartmental Division of Critical Care Medicine (R.P., D.C.S.), and the Department of Medicine (R.P., P.D., D.C.S.), Temerty Faculty of Medicine, University of Toronto, the Sunnybrook Centre for Prehospital Medicine (S.C., P.R.V., L.T., M.F.), the Departments of Emergency Services (I.R.D., L.J.M.) and Critical Care Medicine (R.P., D.C.S.), Sunnybrook Health Sciences Centre, the Schwartz/Reisman Emergency Medicine Institute, Sinai Health (S.L.M.), and the Division of Cardiology, Unity Health Toronto (P.D.), Toronto, the Division of Emergency Medicine, London Health Sciences Centre, Department of Medicine, University of Western Ontario, London (M.D.), and the Department of Emergency Medicine, Ottawa Hospital Research Institute, Ottawa (C.V.) - all in Canada
| | - Damon C Scales
- From the Division of Emergency Medicine, Department of Family and Community Medicine (S.C., I.R.D., S.L.M.), the Division of Emergency Medicine, Department of Medicine, (P.R.V., L.J.M.), the Interdepartmental Division of Critical Care Medicine (R.P., D.C.S.), and the Department of Medicine (R.P., P.D., D.C.S.), Temerty Faculty of Medicine, University of Toronto, the Sunnybrook Centre for Prehospital Medicine (S.C., P.R.V., L.T., M.F.), the Departments of Emergency Services (I.R.D., L.J.M.) and Critical Care Medicine (R.P., D.C.S.), Sunnybrook Health Sciences Centre, the Schwartz/Reisman Emergency Medicine Institute, Sinai Health (S.L.M.), and the Division of Cardiology, Unity Health Toronto (P.D.), Toronto, the Division of Emergency Medicine, London Health Sciences Centre, Department of Medicine, University of Western Ontario, London (M.D.), and the Department of Emergency Medicine, Ottawa Hospital Research Institute, Ottawa (C.V.) - all in Canada
| |
Collapse
|
6
|
Kulangareth NV, Magtibay K, Massé S, Krishnakumar Nair, Dorian P, Nanthakumar K, Umapathy K. An In-Silico model for evaluating the directional shock vectors in terminating and modulating rotors. Comput Biol Med 2022; 146:105665. [DOI: 10.1016/j.compbiomed.2022.105665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 05/03/2022] [Accepted: 05/19/2022] [Indexed: 11/27/2022]
|
7
|
Roach C, Tainter CR, Sell RE, Wardi G. Resuscitating Resuscitation: Advanced Therapies for Resistant Ventricular Dysrhythmias. J Emerg Med 2020; 60:331-341. [PMID: 33339645 DOI: 10.1016/j.jemermed.2020.10.051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 10/22/2020] [Indexed: 10/22/2022]
Abstract
BACKGROUND More than 640,000 combined in-hospital and out-of-hospital cardiac arrests occur annually in the United States. However, survival rates and meaningful neurologic recovery remain poor. Although "shockable" rhythms (i.e., ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT)) have the best outcomes, many of these ventricular dysrhythmias fail to return to a perfusing rhythm (resistant VF/VT), or recur shortly after they are resolved (recurrent VF/VT). OBJECTIVE This review discusses 4 emerging therapies in the emergency department for treating these resistant or recurrent ventricular dysrhythmias: beta-blocker therapy, dual simultaneous external defibrillation, stellate ganglion blockade, and extracorporeal cardiopulmonary resuscitation. We discuss the underlying physiology of each therapy, review relevant literature, describe when these approaches should be considered, and provide evidence-based recommendations for these techniques. DISCUSSION Esmolol may mitigate some of epinephrine's negative effects when used during resuscitation, improving both postresuscitation cardiac function and long-term survival. Dual simultaneous external defibrillation targets the region of the heart where ventricular fibrillation typically resumes and may apply a more efficient defibrillation across the heart, leading to higher rates of successful defibrillation. Stellate ganglion blocks, recently described in the emergency medicine literature, have been used to treat patients with recurrent VF/VT, resulting in significant dysrhythmia suppression. Finally, extracorporeal cardiopulmonary resuscitation is used to provide cardiopulmonary support while clinicians correct reversible causes of arrest, potentially resulting in improved survival and good neurologic functional outcomes. CONCLUSION These emerging therapies do not represent standard practice; however, they may be considered in the appropriate clinical scenario when standard therapies are exhausted without success.
Collapse
Affiliation(s)
- Colin Roach
- Department of Emergency Medicine, University of California, San Diego, San Diego, California
| | - Christopher R Tainter
- Department of Anesthesiology, Division of Critical Care, University of California, San Diego, San Diego, California
| | - Rebecca E Sell
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of California, San Diego, San Diego, California
| | - Gabriel Wardi
- Department of Emergency Medicine, University of California, San Diego, San Diego, California; Division of Pulmonary, Critical Care, and Sleep Medicine, University of California, San Diego, San Diego, California
| |
Collapse
|
8
|
Deakin CD, Morley P, Soar J, Drennan IR. Double (dual) sequential defibrillation for refractory ventricular fibrillation cardiac arrest: A systematic review. Resuscitation 2020; 155:24-31. [PMID: 32561473 DOI: 10.1016/j.resuscitation.2020.06.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 06/05/2020] [Accepted: 06/09/2020] [Indexed: 01/01/2023]
Abstract
INTRODUCTION Cardiac arrests associated with shockable rhythms such as ventricular fibrillation or pulseless VT (VF/pVT) are associated with improved outcomes from cardiac arrest. The more defibrillation attempts required to terminate VF/pVT, the lower the survival. Double sequential defibrillation (DSD) has been used for refractory VF/pVT cardiac arrest despite limited evidence examining this practice. We performed a systematic review to summarize the evidence related to the use of DSD during cardiac arrest. METHODS This review was performed according to PRISMA and registered on PROSPERO (ID: CRD42020152575). We searched Embase, Pubmed, and the Cochrane library from inception to 28 February 2020. We included adult patients with VF/pVT in any setting. We excluded case studies, case series with less than five patients, conference abstracts, simulation studies, and protocols for clinical trials. We predefined our outcomes of interest as neurological outcome, survival to hospital discharge, survival to hospital admission, return of spontaneous circulation (ROSC), and termination of VF/pVT. Risk of bias was examined using ROBINS-I or ROB-2 and certainty of studies were reported according to GRADE methodology. RESULTS Overall, 314 studies were identified during the initial search. One hundred and thirty studies were screened during title and abstract stage and 10 studies underwent full manuscript screening, nine included in the final analysis. Included studies were cohort studies (n = 4), case series (n = 3), case-control study (n = 1) and a prospective pilot clinical trial (n-1). All studies were considered to have serious or critical risk of bias and no meta-analysis was performed. Overall, we did not find any differences in terms of neurological outcome, survival to hospital discharge, survival to hospital admission, ROSC, or termination of VF/pVT between DSD and a standard defibrillation strategy. CONCLUSION The use of double sequential defibrillation was not associated with improved outcomes from out-of-hospital cardiac arrest, however the current literature has a number of limitations to interpretation. Further high-quality evidence is needed to answer this important question.
Collapse
Affiliation(s)
- Charles D Deakin
- University Hospital Southampton NHS Foundation Trust, Southampton, UK; South Central Ambulance Service NHS Foundation Trust, Otterbourne, UK.
| | - Peter Morley
- Royal Melbourne Hospital, Melbourne, Australia; Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Melbourne, Australia
| | - Jasmeet Soar
- Southmead Hospital, North Bristol NHS Trust, Bristol, UK
| | - Ian R Drennan
- Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, ON, Canada; Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada; Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| |
Collapse
|
9
|
Cheskes S, Dorian P, Feldman M, McLeod S, Scales DC, Pinto R, Turner L, Morrison LJ, Drennan IR, Verbeek PR. Double sequential external defibrillation for refractory ventricular fibrillation: The DOSE VF pilot randomized controlled trial. Resuscitation 2020; 150:178-184. [DOI: 10.1016/j.resuscitation.2020.02.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 01/26/2020] [Accepted: 02/12/2020] [Indexed: 10/25/2022]
|
10
|
Tate JD, Pilcher TA, Aras KK, Burton BM, MacLeod RS. Validating defibrillation simulation in a human-shaped phantom. Heart Rhythm 2019; 17:661-668. [PMID: 31765807 DOI: 10.1016/j.hrthm.2019.11.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Indexed: 01/23/2023]
Abstract
BACKGROUND We previously developed a computational model to aid clinicians in positioning implantable cardioverter-defibrillators (ICDs), especially in the case of abnormal anatomies that commonly arise in pediatric cases. We have validated the model clinically on the body surface; however, validation within the volume of the heart is required to establish complete confidence in the model and improve its use in clinical settings. OBJECTIVE The goal of this study was to use an animal model and thoracic phantom to record the ICD potential field within the heart and on the torso to validate our defibrillation simulation system. METHODS We recorded defibrillator shock potentials from an ICD suspended together with an animal heart in a human-shaped torso tank and compared them with simulated values. We also compared the scaled distribution threshold, an analog to the defibrillation threshold, calculated from the measured and simulated electric fields within the myocardium. RESULTS ICD potentials recorded on the tank and cardiac surface and within the myocardium agreed well with those predicted by the simulation. A quantitative comparison of the recorded and simulated potentials yielded a mean correlation of 0.94 and a relative error of 19.1%. The simulation can also predict scaled distribution thresholds similar to those calculated from the measured potential fields. CONCLUSION We found that our simulation could predict potential fields with high correlation with the measured values within the heart and on the torso surface. These results support the use of this model for the optimization of ICD placements.
Collapse
Affiliation(s)
- Jess D Tate
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah; Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, Utah.
| | - Thomas A Pilcher
- Division of Pediatric Cardiology, University of Utah, Salt Lake City, Utah
| | - Kedar K Aras
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah; Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, Utah
| | - Brett M Burton
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah; Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, Utah
| | - Rob S MacLeod
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah; Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, Utah
| |
Collapse
|
11
|
Tate J, Stinstra J, Pilcher T, Poursaid A, Jolley MA, Saarel E, Triedman J, MacLeod RS. Measuring defibrillator surface potentials: The validation of a predictive defibrillation computer model. Comput Biol Med 2018; 102:402-410. [PMID: 30195579 DOI: 10.1016/j.compbiomed.2018.08.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 08/24/2018] [Accepted: 08/24/2018] [Indexed: 01/26/2023]
Abstract
Implantable cardioverter defibrillators (ICDs) are commonly used to reduce the risk in patients with life-threatening arrhythmias, however, clinicians have little systematic guidance to place the device, especially in cases of unusual anatomy. We have previously developed a computational model that evaluates the efficacy of a delivered shock as a clinical and research aid to guide ICD placement on a patient specific basis. We report here on progress to validate this model with measured ICD surface potential maps from patients undergoing ICD implantation and testing for defibrillation threshold (DFT). We obtained body surface potential maps of the defibrillation pulses by adapting a limited lead selection and potential estimation algorithm to deal with the limited space for recording electrodes. Comparison of the simulated and measured potential maps of the defibrillation shock yielded similar patterns, a typical correlation greater than 0.9, and a relative error less than 15%. Comparison of defibrillation thresholds also showed accurate prediction of the simulations. The high agreement of the potential maps and DFTs suggests that the predictive simulation generates realistic potential values and can accurately predict DFTs in patients. These validation results pave the way for use of this model in optimization studies prior to device implantation.
Collapse
Affiliation(s)
- Jess Tate
- Department of Bioengineering, University of Utah, Salt Lake City, USA; Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, USA.
| | - Jeroen Stinstra
- Department of Bioengineering, University of Utah, Salt Lake City, USA; Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, USA
| | - Thomas Pilcher
- Division of Pediatric Cardiology, University of Utah, Salt Lake City, USA
| | - Ahrash Poursaid
- Department of Bioengineering, University of Utah, Salt Lake City, USA; Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, USA
| | - Matthew A Jolley
- Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, USA
| | - Elizabeth Saarel
- Division of Pediatric Cardiology, University of Utah, Salt Lake City, USA
| | - John Triedman
- Department of Cardiology, Children's Hospital Boston, Boston, Massachusetts, USA
| | - Rob S MacLeod
- Department of Bioengineering, University of Utah, Salt Lake City, USA; Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, USA
| |
Collapse
|
12
|
Bioelectrodes. Biomater Sci 2013. [DOI: 10.1016/b978-0-08-087780-8.00082-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
13
|
Effect of cardiogenic pulmonary edema on defibrillation efficacy. Int J Cardiol 2010; 144:76-9. [PMID: 19155073 DOI: 10.1016/j.ijcard.2008.12.047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2008] [Accepted: 12/06/2008] [Indexed: 11/23/2022]
|
14
|
Yang F, Patterson R. Optimal Transvenous Coil Position on Active-can Single-coil ICD Defibrillation Efficacy: A Simulation Study. Ann Biomed Eng 2008; 36:1659-67. [DOI: 10.1007/s10439-008-9548-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2008] [Accepted: 07/31/2008] [Indexed: 11/30/2022]
|
15
|
KILLINGSWORTH CHERYLR, RIPPY MARIANK, VIRMANI RENU, ROLLINS DENNISL, McGIFFIN DAVIDC, IDEKER RAYMONDE. Evaluation of a Novel Ventricular Support Device with Defibrillation Capabilities in Canine and Porcine Animal Models. J Cardiovasc Electrophysiol 2008; 19:851-7. [DOI: 10.1111/j.1540-8167.2008.01132.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
16
|
Rosborough JP, Deno DC, Walker RG, Niemann JT. A percutaneous catheter-based system for the measurement of potential gradients applicable to the study of transthoracic defibrillation. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2007; 30:166-74. [PMID: 17338711 DOI: 10.1111/j.1540-8159.2007.00645.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND The local electric (E) field or potential gradient produced by a shock reliably predicts VF termination. In this study we evaluated a multiple electrode, catheter-based device for closed-chest 3D measurements of E field from transthoracic defibrillation shocks. METHODS Catheters with multiple electrodes on the tip were placed in intracardiac locations in anesthetized swine. An empirically derived calibration matrix and custom microprocessor was used to transform simultaneously measured voltages into orthogonal E field vector components. E fields produced in six intracardiac locations by 30 and 300 J shocks were compared in eight animals. Correlations were determined for measured current and E field at various shock strengths at two different transthoracic impedances in five additional animals. VF was induced in 12 animals and E field measured during defibrillation attempts. RESULTS The E field measurements resulting for 30 J transthoracic shocks were not significantly different among different intracardiac sites. At 300 J, however, significant differences were observed between sites with the greatest intensities recorded in the coronary sinus and right ventricle. Within animals, the variability of the measurement at each site was small, ranging from 2.8 +/- 1.6% to 5.7 +/- 4.5%. Significant correlations (P < 0.001) between measured E field and peak current were observed at native impedance (34 +/- 4 Omega, r = 0.81) and at adjusted impedance (76 +/- 4 Omega, r = 0.78) with transthoracic shocks of 200, 300, and 360 J. In VF studies, the probability of defibrillation was closely fit by a sigmoidal dose response curve in the coronary sinus E field with an approximate threshold of 4.7 V/cm with 50% defibrillation success at 9.3 V/cm. CONCLUSIONS The measured intracardiac E field variability within animals and at a specific site was small, exhibiting a median value of 5.1%, contrasted to median variabilities across animals of 5-11% suggesting the capacity of this measurement system to provide subject specific information on the distribution of E fields. The measured E field magnitudes across animals in the coronary sinus were linearly correlated with applied shock current with a very strong linear relation to effective shock voltage observed in vitro in a saline tank. When evaluated as a predictor of shock success, the observed values were consistent with previously reported critical fields. This technique may be of value in evaluating waveforms for transthoracic defibrillation as well as electrode size, placement, and composition.
Collapse
Affiliation(s)
- John P Rosborough
- Department of Emergency Medicine, Harbor-UCLA Medical Center, Torrance, California 90509, USA
| | | | | | | |
Collapse
|
17
|
Abstract
Intravascular ventricular defibrillation and intravascular atrial defibrillation have many similarities. An important factor influencing the outcome of the shock is the potential gradient field created throughout the ventricles or the atria by the shock. A minimum potential gradient is required throughout the ventricles and probably the atria in order to defibrillate. The value of this minimum potential gradient is affected by several factors, including the duration, tilt, and number of phases of the waveform. For shock strengths near the defibrillation threshold, earliest activation following failed shocks arises in a region in which the potential gradient is low. The defibrillation threshold energy can be decreased by adding a third and even a fourth defibrillation electrode in regions where the shock potential gradient is low for the shock field created by the first two defibrillation electrodes and giving two sequential shocks, each through a different set of electrodes. However, the addition of more electrodes and sequential shocks complicates both the device and its implantation. Because patients are conscious when the atrial defibrillation shock is given, they experience pain during the shock, which is one of the main drawbacks of intravascular atrial defibrillation. Unfortunately, the pain threshold for defibrillation shocks is so low that a shock less than 1 J is uncomfortable and is not much less painful than shocks several times stronger. Therefore, even though electrode configurations exist that have lower atrial defibrillation threshold energy requirements than the atrial defibrillation threshold with standard defibrillation electrode configurations used in implantable cardioverter-defibrillators (ICDs) for ventricular defibrillation, they are not clinically practical because their shocks are almost as painful as with the standard ICD electrode configurations. Such electrode configurations would make the ICD more complicated, leading to greater difficulty and longer time required for implantation.
Collapse
Affiliation(s)
- Derek J. Dosdall
- Department of Biomedical Engineering, University of Alabama at Birmingham, Alabama, USA
| | - Raymond E. Ideker
- Department of Biomedical Engineering, University of Alabama at Birmingham, Alabama, USA
- Department of Medicine, University of Alabama at Birmingham, Alabama, USA
- Department of Physiology Birmingham, University of Alabama at Birmingham, Alabama, USA
| |
Collapse
|
18
|
Molina JE, Benditt DG. An Epicardial Subxiphoid Implantable Defibrillator Lead:. Superior Effectiveness After Failure of Standard Implants. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2004; 27:1500-6. [PMID: 15546304 DOI: 10.1111/j.1540-8159.2004.00667.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A single epicardial implantable lead using the subxiphoid approach is described in this article. It consists of a single halo-shaped coil that is implanted under the inferior surface of the heart, including the right and left inferior ventricular surfaces. It has been implanted in four patients who could not be defibrillated with a transvenous system, even with the adjunct use of subcutaneous leads or left chest wall patch. Three of the patients had progressive heart failure due to ischemic myocardiopathy; the fourth patient had a dilated idiopathic myocardiopathy. The approach is simple and appears to be effective due to its ability to encompass the left and right ventricles. This vector seems to significantly lower the threshold for defibrillation, and may offer substantial benefit in the setting of high defibrillation thresholds with conventional leads, or when conventional systems are inadequate to achieve consistent defibrillation.
Collapse
Affiliation(s)
- J Ernesto Molina
- Department of Surgery, Division of Cardiovascular and Thoracic Surgery, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA.
| | | |
Collapse
|
19
|
Mocanu D, Kettenbach J, Sweeney MO, Kikinis R, Kenknight BH, Eisenberg SR. A comparison of biventricular and conventional transvenous defibrillation: a computational study using patient derived models. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2004; 27:586-93. [PMID: 15125713 DOI: 10.1111/j.1540-8159.2004.00491.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Conventional transvenous defibrillation is performed with an ICD using a dual current pathway. The defibrillation energy is delivered from the RV electrode to the superior vena cava (SVC) electrode and the metallic case (CAN) of the ICD. Biventricular defibrillation uses an additional electrode placed in the LV free wall with sequential shocks to create an additional current vector. Clinical studies of biventricular defibrillation have reported a 45% reduction in mean defibrillation threshold (DFT) energy. The aim of the study was to use computational methods to examine the biventricular defibrillation fields together with their corresponding DFTs in a variety of patient derived models and to compare them to simulations of conventional defibrillation. A library of thoracic models derived from nine patients was used to solve for electric field distributions. The defibrillation waveform consisted of a LV --> SVC + CAN monophasic shock followed by a biphasic shock delivered via the RV --> SVC + CAN electrodes. When the initial voltage of the two shocks is the same, the simulations show that the biventricular configuration reduces the mean DFT by 46% (3.5 +/- 1.3 vs 5.5 +/- 2.7 J, P = 0.005). When the leading edge of the biphasic shock is equal to the trailing edge of the monophasic shock, there is no statistically significant difference in the mean DFT (4.9 +/- 1.9 vs 5.5 +/- 2.7 J, P > 0.05) with the DFT decreasing in some patients and increasing in others. These results suggest that patient-specific computational models may be able to identify those patients who would most benefit from a biventricular configuration.
Collapse
Affiliation(s)
- Daniel Mocanu
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215, USA
| | | | | | | | | | | |
Collapse
|
20
|
Hillebrenner MG, Eason JC, Campbell CA, Trayanova NA. Postshock arrhythmogenesis in a slice of the canine heart. J Cardiovasc Electrophysiol 2004; 14:S249-56. [PMID: 14760930 DOI: 10.1046/j.1540.8167.90317.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Recent evidence has demonstrated that defibrillation shocks terminate or reset reentrant activity in the myocardium through the generation of virtual electrode polarization (VEP). Previous research has revealed that the shock establishes phase singularities (PSs) in the tissue via the VEP mechanism. The aim of this study was to examine, as a function of shock strength and electrode configuration, the relationship between end-shock PSs and the reentrant circuits established after failed defibrillation attempts. METHODS AND RESULTS The study uses a complex three-dimensional finite-element bidomain model of a slice of the canine heart characterized by realistic geometry and fiber architecture and undergoing a single scroll wave. Defibrillation shocks of increasing strength are delivered through three different electrode configurations. The results demonstrated that >98% of all PSs have a lifetime of half a reentrant cycle or less. Stronger shocks result in a faster rate of annihilation of postshock PSs. For failed shocks, the surviving PSs underlie the activity of one or more scroll waves, which remain stationary in the slice. For all electrode configurations tested, the increase in shock strength leads to a rapid initial increase in the number of postshock reentries followed by a slower decrease; similar behavior is observed with regard to end-shock PSs. CONCLUSION These results present new evidence regarding the mechanisms underlying failure of defibrillation shocks.
Collapse
Affiliation(s)
- Matthew G Hillebrenner
- Department of Biomedical Engineering, Tulane University, New Orleans, Louisiana 70118, USA
| | | | | | | |
Collapse
|
21
|
Yoon RS, DeMonte TP, Hasanov KF, Jorgenson DB, Joy MLG. Measurement of thoracic current flow in pigs for the study of defibrillation and cardioversion. IEEE Trans Biomed Eng 2003; 50:1167-73. [PMID: 14560770 DOI: 10.1109/tbme.2003.816082] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Although defibrillation has been in clinical use for more than 50 years, the complete current flow distribution inside the body during a defibrillation procedure has never been directly measured. This is due to the lack of appropriate imaging technology to noninvasively monitor the current flow inside the body. The current density imaging (CDI) technique, using a magnetic resonance (MR) imager, provides a new approach to this problem [Scott et al. (1991)]. CDI measures the local magnetic field generated by the current and calculates the current density by computing its curl. In this study, CDI was used to measure current density at all points within a postmortem pig torso during an electrical current application through defibrillation electrodes. Furthermore, current flow information was visualized along the chest wall and within the chest cavity using streamline analysis. As expected, some of the highest current densities were observed in the chest wall. However, current density distribution varied significantly from one region to another, possibly reflecting underlying heterogeneous tissue conductivity and anisotropy. Moreover, the current flow analysis revealed many complex and unexpected current flow patterns that have never been observed before. This study has, for the first time, noninvasively measured the volume current measurement inside the pig torso.
Collapse
Affiliation(s)
- Richard S Yoon
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, 4 Taddle Creek Road, Room 407, Toronto, ON M5S 3G9, Canada
| | | | | | | | | |
Collapse
|
22
|
Kloppe A, Müller S, Prenger-Berninghoff A, Drewes C, Hexamer M, Mügge A, Werner J. [Biventricular defibrillation using transvenous electrodes]. BIOMED ENG-BIOMED TE 2003; 47 Suppl 1 Pt 1:127-9. [PMID: 12451792 DOI: 10.1515/bmte.2002.47.s1a.127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
This study investigated the feasibility of transvenous biventricular defibrillation using an electrode in a left ventricular vein. The standard lead configuration with a coil in the right ventricle (RV) and a coil in the superior vena cava (SVC) was compared with an additional unipolar coil in an accessible epicardial vein. Only biphasic shocks were used with different shocking modes between the coils in the RV, LV, SVC and the ICD-generator (CAN). Shocks were applied starting with 30 J, decreasing till the DFT was reached. As a result there is a lower DFT when defibrillation is performed including the left ventricular electrode. The impedance did not show a significant increase after more then 20 consecutive shocks. It is a feasible and workable application that might help to reduce the energy demand and increase the safety of such a system.
Collapse
Affiliation(s)
- A Kloppe
- Institut für Biomedizinische Technik, Medizinische Fakultät, Ruhr-Universität Bochum.
| | | | | | | | | | | | | |
Collapse
|
23
|
Russomanno DJ, Hicks K. A Prolog-based centroid algorithm for isovolume extraction from finite element torso simulations. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2002; 67:105-114. [PMID: 11809317 DOI: 10.1016/s0169-2607(01)00118-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Computer modeling and simulation of the human torso provides a rapid and non-invasive means to observe the effects of implanted defibrillators. The objective of this study was to improve a method of extracting data from an implanted defibrillator simulation for subsequent visualization. Electrical quantities, such as the potential and gradient fields, are computed at points throughout various regions of a three-dimensional (3-D) torso model via a finite element solution. Software is then implemented in the Prolog language to extract and visualize a subset of the data, from within any subregion of the model, satisfying a given declarative constraint. In past work, membership in these subsets had been determined solely by the electrical quantities at the vertices of the tetrahedral elements within the model along with an arbitrary choice made by the user. However, this study expands upon previous work to utilize an alternative means of classification, calculating the centroid of each tetrahedron and assigning electrical properties to these centroids based on the distances of each centroid to the four corners of the tetrahedron. After the modifications, it is expected that the extracted subsets of the model will represent the data in a more realistic and conservative manner and provide more insight into the process of defibrillation than previous methods of data extraction and visualization.
Collapse
Affiliation(s)
- David J Russomanno
- Department of Electrical and Computer Engineering, The University of Memphis, Campus Box 526574, Memphis, TN 38152-6574, USA.
| | | |
Collapse
|
24
|
Wang Y, Haynor DR, Kim Y. An investigation of the importance of myocardial anisotropy in finite-element modeling of the heart: methodology and application to the estimation of defibrillation efficacy. IEEE Trans Biomed Eng 2001; 48:1377-89. [PMID: 11759919 DOI: 10.1109/10.966597] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Finite-element (FE) modeling has been widely used in studies of bioelectric phenomena of tissues, including ventricular defibrillation. Most FE models, whether built from anatomical atlases or subject-specific tomographic images, treat the myocardium as an isotropic tissue. However, myocardium has been experimentally shown to have significant anisotropy in its resistivities, although myocardial fiber directions are difficult to measure on a subject-specific basis. In this paper, we: 1). propose a method to incorporate a widely known myocardial fiber direction model to a specific individual and 2). assess the effects of myocardial anisotropy on myocardial voltage gradients computed for a study of implantable defibrillators. The thoracic FE model was built from CT images of a young pig, and the myocardial fiber structures were incorporated via elastic mapping. Our results demonstrate a good mapping of geometry between the source and target hearts with an average root-mean-square error of less than 2.3 mm and a mapped fiber pattern similar to those known to exist in vivo. With the mapped fiber information, we showed that the estimated minimal myocardial voltage gradient over 80% of the myocardium differs by less than 10% between using an isotropic and anisotropic myocardial models. Thus, myocardial anisotropy is expected to have only a small effect on estimates of defibrillation threshold obtained from computed voltage gradients. On the other hand, anisotropy may be essential if defibrillation efficacy is analyzed by transmembrane voltage of the myocardial cells.
Collapse
Affiliation(s)
- Y Wang
- Rosetta Inpharmatics, Inc., Kirkland, WA 98034 USA
| | | | | |
Collapse
|
25
|
Abstract
The patterns of transmembrane potential on the whole heart during and immediately after fibrillation-inducing shocks are unknown. To study arrhythmia induction, we recorded transmembrane activity from the anterior and posterior epicardial surface of the isolated rabbit heart simultaneously using 2 charge-coupled device cameras (32,512 pixels, 480 frames/second). Isolated hearts were paced from the apex at a cycle length of 250 ms. Two shock coils positioned inside the right ventricle (-) and atop the left atrium (+) delivered shocks at 3 strengths (0.75, 1.5, and 2.25 A) and 6 coupling intervals (130 to 230 ms). The patterns of depolarization and repolarization were similar, as is evident in the uniformity of action potential duration at 75% repolarization (131.4¿8.3 ms). At short coupling intervals (<180 ms), shocks hyperpolarized a large portion of the ventricles and produced a pair of counterrotating waves, one on each side of the heart. The first beat after the shock was reentrant in 90% of short coupling interval episodes. At long coupling intervals (>180 ms), increasingly stronger shocks depolarized an increasingly larger portion of the heart. The first beat after the shock was reentrant in 18% of long coupling interval episodes. Arrhythmias were most often induced at short coupling intervals (98%) than at long coupling intervals (35%). The effect and outcome of the shock were related to the refractory state of the heart at the time of the shock. Hyperpolarization occurred at short coupling intervals, whereas depolarization occurred at long coupling intervals. Consistent with the "critical point" hypothesis, increasing shock strength and coupling interval moved the location where reentry formed (away from the shock electrode and pacing electrode, respectively).
Collapse
Affiliation(s)
- I Banville
- Department of Biomedical Engineering, Division of Cardiovascular Disease, University of Alabama at Birmingham, Birmingham, Ala, USA
| | | | | | | |
Collapse
|
26
|
Wang Y, Schimpf PH, Haynor DR, Bardy GH, Kim Y. Analysis of defibrillation efficacy from myocardial voltage gradients with finite element modeling. IEEE Trans Biomed Eng 1999; 46:1025-36. [PMID: 10493065 DOI: 10.1109/10.784133] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Increasing defibrillation efficacy by lowering the defibrillation threshold (DFT) is an important goal in positioning implantable cardioverter-defibrillator electrodes. Clinically, the DFT is difficult to estimate noninvasively. It has been suggested that the DFT relates to the myocardial voltage gradient distribution, but this relation has not been quantitatively demonstrated. We analyzed the relation between the experimentally measured DFT's and the simulated myocardial voltage gradients provided by finite element modeling. We performed a series of experiments in 11 pigs to measure the DFT's, and created and solved three-dimensional subject-specific finite element models to assess the correlation between the computed myocardial voltage gradient histograms and the DFT's. Our data show a statistically significant correlation between the DFT and the left ventricular voltage gradient distribution, with the septal region being more significant (correlation coefficient of 0.74) than other myocardial regions. The correlation between the DFT and the right ventricular and the atrial voltage gradient, on the other hand, is not significant.
Collapse
Affiliation(s)
- Y Wang
- Department of Bioengineering, University of Washington, Seattle 98195, USA
| | | | | | | | | |
Collapse
|
27
|
Favale S, Dicandia CD, Tunzi P, Rizzon P. A prospective, randomized, comparison in patients between a pectoral unipolar defibrillation system and that using an additional inferior vena cava electrode. Pacing Clin Electrophysiol 1999; 22:1140-5. [PMID: 10461288 DOI: 10.1111/j.1540-8159.1999.tb00592.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The decrease of defibrillation energy requirement would render the currently available transvenous defibrillator more effective and favor the device miniaturization process and the increase of longevity. The unipolar defibrillation systems using a single RV electrode and the pectoral pulse generator titanium shell (CAN) proved to be very efficient. The addition of a third defibrillating electrode in the coronary sinus did not prove to offer advantages and in the superior vena cava showed only a slight reduction of the defibrillation threshold (DFT). The purpose of this study was to determine whether the defibrillation efficacy of the single lead unipolar transvenous system could be improved by adding an electrode in the inferior vena cava (IVC). In 17 patients, we prospectively and randomly compared the DFT obtained with a single lead unipolar system with the DFT obtained using an additional of an IVC lead. The RV electrode, Medtronic 6936, was used as anode (first phase of biphasic) in both configurations. A 108 cm2 surface CAN, Medtronic 7219/7220 C, was inserted in a left submuscular infraclavicular pocket and used as cathode, alone or in combination with IVC, Medtronic 6933. The superior edge of the IVC coil was positioned 2-3 cm below the right atrium-IVC junction. Thus, using biphasic 65% tilt pulses generated by a 120 microF external defibrillator, Medtronic D.I.S.D. 5358 CL, the RV-CAN DFT was compared with that obtained with the RV-CAN plus IVC configuration. Mean energy DFTs were 7.8 +/- 3.6 and 4.8 +/- 1.7 J (P < 0.0001) and mean impedance 65.8 +/- 13 O and 43.1 +/- 5.5 O (P < 0.0001) with the RV-CAN and the IVC configuration, respectively. The addition of IVC significantly reduces the DFT of a single lead active CAN pectoral pulse generator. The clinical use of this biphasic and dual pathway configuration may be considered in patients not meeting implant criteria with the single lead or the dual lead RV-superior vena cava systems. This configuration may also prove helpful in the use of very small, low output ICDs, where the clinical impact of ICD generator size, longevity, and related cost may offset the problems of dual lead systems.
Collapse
Affiliation(s)
- S Favale
- Department of Metodologia Clinica e Tecnologie Medico-Chirurgiche, University of Bari, Italy.
| | | | | | | |
Collapse
|
28
|
Friedman PA, Rasmussen MJ, Grice S, Trusty J, Glikson M, Stanton MS. Defibrillation thresholds are increased by right-sided implantation of totally transvenous implantable cardioverter defibrillators. Pacing Clin Electrophysiol 1999; 22:1186-92. [PMID: 10461295 DOI: 10.1111/j.1540-8159.1999.tb00599.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Whether an ICD is placed via a left- or right-sided approach depends on venous access, the presence of a preexisting pacemaker, and other factors. Since the DFT is affected by lead position, which in turn is determined in part by the side of access, right-sided venous access could adversely affect DFTs. Furthermore, right-sided active can placement directs electric current toward the right hemithorax, which could further increase DFTs. This study sought to determine whether DFTs were increased by right-sided vascular access, and whether active can technology was beneficial or detrimental with right-sided ICD placement. Stepdown to failure DFTs were found in 290 patients receiving transvenous systems at the time of initial ICD implantation. Of these, 271 (93%) received left-sided systems and 19 (7%) received right-sided systems. The mean DFT in systems placed via left-sided vascular access was 11.3 +/- 5.3 J versus 17.0 +/- 4.9 J for right-sided implantation (P < 0.0001); right-sided DFTs were elevated for both active can and cold can systems. Right-sided active can devices had a lower DFT than right-sided cold can systems (15 +/- 4.1 J vs 19 +/- 4.8 J, P = 0.05). The right-sided implantation of implantable defibrillators results in significantly higher DFTs than the left-sided approach. This may be due to the less favorable distribution of the defibrillating field relative to the myocardium with the devices on the right. When right-sided implantation is clinically mandated, active can devices result in lower thresholds and should be used.
Collapse
Affiliation(s)
- P A Friedman
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota 55905, USA.
| | | | | | | | | | | |
Collapse
|
29
|
Windecker S, Ideker RE, Plumb VJ, Kay GN, Walcott GP, Epstein AE. The influence of ventricular fibrillation duration on defibrillation efficacy using biphasic waveforms in humans. J Am Coll Cardiol 1999; 33:33-8. [PMID: 9935005 DOI: 10.1016/s0735-1097(98)00529-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVES The purpose of this study was to prospectively investigate the influence of ventricular fibrillation (VF) durations of 5, 10 and 20 s on the defibrillation threshold (DFT) during implantable cardioverter-defibrillator (ICD) implantation. BACKGROUND Although the DFT using monophasic waveforms has been shown to increase with VF duration in humans, the effect of VF duration on defibrillation efficacy using biphasic waveforms in humans is not known. METHODS Thirty patients undergoing primary ICD implantation or pulse generator replacement were randomly assigned to have the DFT determined using biphasic shocks at two durations of VF each (5 and 10 s, 10 and 20 s or 5 and 20 s). RESULTS There was no statistically significant difference in the mean DFT comparing VF durations of 5 s (9.5+/-6.0 J) and 10 s (10.8+/-7.0 J) (p=0.4). The mean DFT significantly increased from 10.9+/-6.1 J at 10 s of VF to 12.6+/-5.6 J (p=0.03) at 20 s of VF, and from 7.0+/-3.5 J at 5 s of VF to 10.5+/-6.3 J (p=0.04) at 20 s of VF. An increase in the DFT was observed in 14 patients as VF duration increased. There were no clinical characteristics that differentiated patients with and without an increase in the DFT. CONCLUSIONS Defibrillation efficacy decreases with increasing VF duration using biphasic waveforms in humans. Ventricular fibrillation durations greater than 10 s may negatively affect the effectiveness of ICD therapy.
Collapse
Affiliation(s)
- S Windecker
- Department of Medicine, The University of Alabama at Birmingham, 35294, USA
| | | | | | | | | | | |
Collapse
|
30
|
Aguel F, Eason JC, Trayanova NA, Siekas G, Fishler MG. Impact of transvenous lead position on active-can ICD defibrillation: a computer simulation study. Pacing Clin Electrophysiol 1999; 22:158-64. [PMID: 9990622 DOI: 10.1111/j.1540-8159.1999.tb00324.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Optimizing lead placement in transvenous defibrillation remains central to the clinical aspects of the defibrillation procedure. Studies involving superior vena cava (SVC) return electrodes have found that left ventricular (LV) leads or septal positioning of the right ventricular (RV) lead minimizes the voltage defibrillation threshold (VDFT) in endocardial lead-->SVC defibrillation systems. However, similar studies have not been conducted for active-can configurations. The goal of this study was to determine the optimal lead position to minimize the VDFT for systems incorporating an active can. This study used a high resolution finite element model of a human torso that includes the fiber architecture of the ventricular myocardium to find the role of lead positioning in a transvenous LEAD-->can defibrillation electrode system. It was found that, among single lead systems, posterior positioning of leads in the right ventricle lowers VDFTs appreciably. Furthermore, a septal location of leads resulted in lower VDFTs than free-wall positioning. Increasing the number of leads, and thus the effective lead surface area in the right ventricle also resulted in lower VDFTs. However, the lead configuration that resulted in the lowest VDFTs is a combination of mid-cavity right ventricle lead and a mid-cavity left ventricle lead. The addition of a left ventricular lead resulted in a reduction in the size of the low gradient regions and a change of its location from the left ventricular free wall to the septal wall.
Collapse
Affiliation(s)
- F Aguel
- Tulane University, Department of Biomedical Engineering, New Orleans, Louisiana 70118, USA
| | | | | | | | | |
Collapse
|
31
|
Plewan A, Valina C, Herrmann R, Alt E. Initial experience with a new balloon-guided single lead catheter for internal cardioversion of atrial fibrillation and dual chamber pacing. Pacing Clin Electrophysiol 1999; 22:228-32. [PMID: 9990636 DOI: 10.1111/j.1540-8159.1999.tb00338.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Based on the observation that internal cardioversion (IntCV) of atrial fibrillation is effective with electrodes in the right atrium and pulmonary artery, a new balloon-guided catheter and external defibrillation device with optional dual chamber pacing was evaluated. METHODS IntCV was attempted in 27 patients (age: 57 +/- 10 years, duration: 14 +/- 18 months, left atrial diameter 56 +/- 8 mm) using a new defibrillation device (Alert, EP MedSystems, Inc., NJ, USA) that allows the delivery of biphasic shocks (0.5-15 J, variable tilt), atrial and ventricular pacing, and online signal recording. Pacing and defibrillation shocks were applied via a 7.5 Fr balloon-guided catheter (EP MedSystems, Inc.). Pacing, sensing, and triggering were established through the proximal atrial array and an electrode ring between both defibrillation arrays and a single ventricular electrode ring. Catheters were inserted from the antecubital vein. RESULTS In 25 of 27 patients sinus rhythm was restored with a mean energy of 6.7 +/- 4.5 J. In five patients, atrial postshock pacing was required for bradycardia and atrial premature beats. The mean fluoroscopy time was 2.0 +/- 1.3 minutes. CONCLUSION The high success rate, ease of application, and backup dual chamber pacing suggest that this system is an alternative to established methods of cardioversion. In certain indications, such as failure of prior external cardioversion and situations in which a standard pulmonary balloon catheter is needed, this system would be advantageous.
Collapse
Affiliation(s)
- A Plewan
- I Medizinische Klinik, Klinikum rechts der Isar, München, Germany
| | | | | | | |
Collapse
|
32
|
Moerman A, Herregods L, Tavernier R, Jordaens L, Struys M, Rolly G. Influence of anaesthesia on defibrillation threshold. Anaesthesia 1998; 53:1156-9. [PMID: 10193216 DOI: 10.1046/j.1365-2044.1998.00643.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Internal cardioverter-defibrillator implantation can be performed under local or general anaesthesia. Whether the technique of general anaesthesia influences the defibrillation threshold remains a matter of debate. We therefore compared, in a prospective, randomised clinical study, the effect of intravenous anaesthesia using propofol with inhalational anaesthesia using isoflurane on the defibrillation threshold in 68 patients scheduled for transvenous single-lead internal cardioverter-defibrillator implantation. Defibrillation threshold was measured at implantation and at device testing 1 week and 1 month after implantation. Patients acted as their own controls. Neither the anaesthetic technique nor the duration of anaesthesia was associated with significant changes in the defibrillation threshold. We conclude that in this group of high-risk patients, both types of anaesthesia are acceptable techniques for internal cardioverter-defibrillator implantation and testing.
Collapse
Affiliation(s)
- A Moerman
- Department of Anaesthesia, University Hospital, Gent, Belgium
| | | | | | | | | | | |
Collapse
|
33
|
Sandstedt B, Kennergren C, Schaumann A, Herse B, Neuzner J. Short- and long-term performance of a tripolar down-sized single lead for implantable cardioverter defibrillator treatment: a randomized prospective European multicenter study. European Endotak DSP Investigator Group. Pacing Clin Electrophysiol 1998; 21:2087-94. [PMID: 9826861 DOI: 10.1111/j.1540-8159.1998.tb01128.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: 11/28/2022]
Abstract
A new, thinner (10 Fr) and more flexible, single-pass transvenous endocardial ICD lead, Endotak DSP, was compared with a conventional lead, Endotak C, as a control in a prospective randomized multicenter study in combination with a nonactive can ICD. A total of 123 patients were enrolled, 55 of whom received a down-sized DSP lead. Lead-alone configuration was successfully implanted in 95% of the DSP patients vs 88% in the control group. The mean defibrillation threshold (DFT) was determined by means of a step-down protocol, and was identical in the two groups, 10.5 +/- 4.8 J in the DSP group versus 10.5 +/- 4.8 J in the control group. At implantation, the DSP mean pacing threshold was lower, 0.51 +/- 0.18 V versus 0.62 +/- 0.35 V (p < 0.05) in the control group, and the mean pacing impedance higher, 594 +/- 110 omega vs 523 +/- 135 omega (p < 0.05). During the follow-up period, the statistically significant difference in thresholds disappeared, while the difference in impedance remained. Tachyarrhythmia treatment by shock or antitachycardia pacing (ATP) was delivered in 53% and 41%, respectively, of the patients with a 100% success rate. In the DSP group, all 28 episodes of polymorphic ventricular tachycardia or ventricular fibrillation were converted by the first shock as compared to 57 of 69 episodes (83%) in the control group (p < 0.05). Monomorphic ventricular tachycardias were terminated by ATP alone in 96% versus 94%. Lead related problems were minor and observed in 5% and 7%, respectively. In summary, both leads were safe and efficacious in the detection and treatment of ventricular tachyarrhythmias. There were no differences between the DSP and control groups regarding short- or long-term lead related complications.
Collapse
Affiliation(s)
- B Sandstedt
- Division of Cardiology, Sahlgrenska University Hospital, Göteborg Sweden
| | | | | | | | | |
Collapse
|
34
|
Cooper RA, Plumb VJ, Epstein AE, Kay GN, Ideker RE. Marked reduction in internal atrial defibrillation thresholds with dual-current pathways and sequential shocks in humans. Circulation 1998; 97:2527-35. [PMID: 9657473 DOI: 10.1161/01.cir.97.25.2527] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND This study tested the ability of sequential shocks delivered through dual-current pathways to lower the atrial defibrillation threshold (ADFT) compared with a biphasic shock through a standard single-current pathway. METHODS AND RESULTS Electrodes were positioned in the right atrial appendage (RA), left subclavian vein (LSV), proximal coronary sinus (CSos), and distal coronary sinus (DCS) in 14 patients with chronic atrial fibrillation (170+/-185 days). Using a step-up protocol, we compared ADFTs for a single-current pathway (RA-->DCS) that used a single 7.5/2.5-ms biphasic shock from a 150-microF capacitor with those for a dual-current pathway system (RA-->DCS followed by CSos-->LSV) using sequential 7.5/2.5-ms biphasic shocks with capacitor discharge waveforms for 150-microF and 600-microF capacitors. Both dual-current pathway configurations (2.0+/-0.4 J for 150-microF capacitance, 2.4+/-0.5 J for 600-microF capacitance) had a significantly lower ADFT than the single-current pathway (5.1+/-1.8 J). Whereas the dual-current pathway with 150-microF capacitor shocks had a significantly lower energy threshold, there was no statistical difference in terms of leading-edge voltage compared with the dual-current pathway with 600-microF capacitance shocks. There were no ventricular arrhythmias induced with appropriately synchronized shocks. CONCLUSIONS For internal atrial defibrillation in humans, sequential biphasic waveforms delivered over dual-current pathways resulted in a markedly reduced (>50% reduction) ADFT compared with a single shock over a single-current pathway.
Collapse
Affiliation(s)
- R A Cooper
- Department of Medicine, The University of Alabama at Birmingham Medical Center, USA.
| | | | | | | | | |
Collapse
|
35
|
Gold MR, Olsovsky MR, Pelini MA, Peters RW, Shorofsky SR. Comparison of single- and dual-coil active pectoral defibrillation lead systems. J Am Coll Cardiol 1998; 31:1391-4. [PMID: 9581739 DOI: 10.1016/s0735-1097(98)00103-x] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVES The purpose of this study was to compare defibrillation thresholds with lead systems consisting of an active left pectoral electrode and either single or dual transvenous coils. BACKGROUND Lead systems that include an active pectoral pulse generator reduce defibrillation thresholds and permit transvenous defibrillation in nearly all patients. A further improvement in defibrillation efficacy is desirable to allow for smaller pulse generators with a reduced maximal output. METHODS This prospective study was performed in 50 consecutive patients. Each patient was evaluated with two lead configurations with the order of testing randomized. Shocks were delivered between the right ventricular coil and either an active can alone (single coil) or an active can with the proximal atrial coil (dual coil). The right ventricular coil was the cathode for the first phase of the biphasic defibrillation waveform. RESULTS Delivered energy at the defibrillation threshold was 10.1+/-5.0 J for the single-coil configuration and 8.7+/-4.0 J for the dual-coil configuration (p < 0.02). Moreover, 98% of patients had low (<15 J) thresholds with the dual-coil lead system, compared with 88% of patients with the single-coil configuration (p=0.05). Leading edge voltage (p < 0.001) and shock impedance (p < 0.001) were also decreased with the dual-coil configuration, although peak current was increased (p < 0.001). CONCLUSIONS A dual-coil, active pectoral lead system reduces defibrillation energy requirements compared with a single-coil, unipolar configuration.
Collapse
Affiliation(s)
- M R Gold
- Department of Medicine, University of Maryland School of Medicine, Baltimore, USA.
| | | | | | | | | |
Collapse
|
36
|
Replogle JA, Russomanno DJ, de Jongh AL, Claydon FJ. Extracting isovolumes from three-dimensional torso geometry using PROLOG. IEEE TRANSACTIONS ON INFORMATION TECHNOLOGY IN BIOMEDICINE : A PUBLICATION OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY 1998; 2:10-9. [PMID: 10719507 DOI: 10.1109/4233.678528] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Three-dimensional (3-D) finite element torso models are widely used to simulate defibrillation field quantities, such as potential, gradient, and current density. These quantities are computed at spatial nodes that comprise the torso model. These spatial nodes typically number between 10(5) and 10(6), which makes the comprehension of torso defibrillation simulation output difficult. Therefore, the objective of this study is to rapidly prototype software to extract a subset of the geometric model of the torso for visualization in which the nodal information associated with the geometry of the model meets a specified threshold value (e.g., minimum gradient). The data extraction software is implemented in PROLOG, which is used to correlate the coordinate, structural, and nodal data of the torso model. A PROLOG-based environment has been developed and is used to rapidly design and test new methods for sorting, collecting, and optimizing data extractions from defibrillation simulations in a human torso model for subsequent visualization.
Collapse
Affiliation(s)
- J A Replogle
- Department of Biomedical Engineering, University of Memphis, TN 38152, USA
| | | | | | | |
Collapse
|
37
|
Friedman PA, Foley DA, Christian TF, Stanton MS. Stability of the defibrillation probability curve with the development of ventricular dysfunction in the canine rapid paced model. Pacing Clin Electrophysiol 1998; 21:339-51. [PMID: 9507535 DOI: 10.1111/j.1540-8159.1998.tb00058.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Most patients with implantable defibrillators have diminished cardiac function. Progressive heart failure might impair defibrillation efficacy, leading to interpreted device failure. This study sought to determine the effect of ventricular dysfunction on defibrillation energy using a biphasic endocardial system. Eleven dogs were ventricularly paced at 225 pulses/min for 2 weeks to induce ventricular dysfunction, and five control dogs remained unpaced. Dose response defibrillation probability curves were generated for each animal at baseline, after 2 weeks (at which time the pacemakers were turned off in the paced group), and then 1 week later. The defibrillation thresholds, ED20, ED50, and ED80 (the 20%, 50%, and 80% effective defibrillation energies, respectively) were determined for each dog at each study. In the paced dogs, the mean ejection fraction fell from 55% to 25% after pacing (P < 0.0001), and rose to 46% after its discontinuation (P = 0.0002). The defibrillation threshold, ED20, ED50, and ED80 remained unchanged in both the control and paced groups for all three studies, even after adjustment for dog weight or left ventricular mass. Rapid pacing produced no change in left ventricular mass. It induced ventricular cavity dilatation and wall thinning, which had opposing effects on defibrillation energy requirements, resulting in no net change of the ED50 in heart failure. In conclusion, the defibrillation efficacy of a biphasic transvenous system is not changed by the development of heart failure using the rapid paced canine model.
Collapse
Affiliation(s)
- P A Friedman
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN 55905, USA
| | | | | | | |
Collapse
|
38
|
Alt E, Ammer R, Lehmann G, Schmitt C, Pasquantonio J, Schömig A. Efficacy of a new balloon catheter for internal cardioversion of chronic atrial fibrillation without anaesthesia. HEART (BRITISH CARDIAC SOCIETY) 1998; 79:128-32. [PMID: 9538303 PMCID: PMC1728613 DOI: 10.1136/hrt.79.2.128] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE To compare a new internal cardioversion system incorporated into a balloon guided catheter with a conventional two electrode system in patients with atrial fibrillation (AF). DESIGN Prospective study. PATIENTS 74 patients with chronic AF treated by internal cardioversion. MATERIALS A 7.5 F balloon catheter with high energy electrode arrays each consisting of six 0.5 cm platinum rings. Brachial vein access enables one electrode array to be placed in the left pulmonary artery (distal pole) and the other at the lateral right atrial wall (proximal pole). The conventional two electrode system consists of 6 F electrodes placed in the proximal left pulmonary artery (anode) and the lower right atrium. INTERVENTIONS Internal cardioversion was performed by shocks delivered in 40 V incremental steps from an external defibrillator. Shocks were applied by the new device to 32 patients (group A) and by the conventional system to 42 patients (group B). RESULTS The groups differed with respect to system positioning (9.2 (7.3) upsilon 12.3 (8.1) minutes, p < 0.05) and fluoroscopy times (1.7 (1.0) v 3.3 (2.1) minutes, p < 0.01). Sinus rhythm was restored in 30 patients of group A and in 39 of group B (NS) with mean (SD) energy requirements of 8.4 (3.1) J and 7.2 (3.1) J, respectively (NS). CONCLUSIONS This new method of internal cardioversion has comparably high primary success rates and low sedation requirements with single and two lead systems.
Collapse
Affiliation(s)
- E Alt
- Department of Cardiology, Deutsches Herzzentrum München, Klinik an der Technischen Universität, Germany.
| | | | | | | | | | | |
Collapse
|
39
|
Yamanouchi Y, Mowrey KA, Niebauer MJ, Tchou PJ, Wilkoff BL. Additional lead improves defibrillation efficacy with an abdominal 'hot can' electrode system. Circulation 1997; 96:4400-7. [PMID: 9416910 DOI: 10.1161/01.cir.96.12.4400] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Although the left prepectoral site is preferred for "hot can" placement, this site is unavailable in some patients. We evaluated the influence of electrode location on defibrillation thresholds with alternative hot can and transvenous lead configurations. METHODS AND RESULTS Three interrelated studies were performed. In group 1, the importance of hot can location was investigated by pairing a right ventricular lead to five different hot can placement sites in seven pigs. The defibrillation energies for right pectoral, left pectoral, left subaxillary, and right and left abdominal hot can sites were 20.3+/-2.7,* 15.9+/-3.8, 14.9+/-2.5, 32.0+/-3.4,* and 30.0+/-3.4 J,* respectively (*P<.005 versus left pectoral and left subaxillary sites). In group 2, the value of a three-electrode configuration with an abdominal hot can placement was investigated by adding a subclavian vein lead to the pectoral or abdominal hot can configurations in seven pigs. The defibrillation energies for left pectoral and abdominal sites were 18.6+/-4.2 and 29.0+/-5.8 J (P=.0001), respectively. The addition of a right or left subclavian vein lead with an abdominal hot can reduced the threshold to 19.3+/-4.2* or 18.8+/-3.2,* respectively (*P=.0001 versus abdominal site). In group 3, the contribution of the abdominal hot can electrode to the three-electrode configuration was tested by a comparison with two purely transvenous two-electrode configurations in six pigs. The defibrillation energy (19.9+/-3.2 J) for the abdominal hot can with a subclavian vein lead was lower than the transvenous lead configurations with a subclavian vein (29.0+/-2.5 J, P=.0001) or a superior vena cava lead (30.7+/-3.7 J, P=.0001). The right ventricular lead was the sole cathode during the first phase of the biphasic shock in all experiments. CONCLUSIONS Defibrillation energy depends on the hot can placement site. The addition of a subclavian vein lead with an abdominal hot can improves defibrillation efficacy to the level of the pectoral placement and is better than a purely transvenous lead configuration.
Collapse
Affiliation(s)
- Y Yamanouchi
- Department of Cardiology, Cleveland Clinic Foundation, Ohio 44195, USA
| | | | | | | | | |
Collapse
|
40
|
Abstract
Lead systems that include an active pectoral shell reduce defibrillation thresholds and permit transvenous defibrillation in nearly all patients. A further improvement in defibrillation efficacy is desirable to allow for smaller pulse generators with a reduced maximum output. Accordingly, the purpose of this study was to compare defibrillation thresholds with multiple transvenous lead systems including those with an active pectoral shell to determine which system would optimize defibrillation energy requirements. This prospective study was performed on 21 consecutive patients. Each subject was evaluated with 3 lead configurations with the order of testing randomized. The configurations were a dual coil transvenous lead (lead), the distal right ventricular coil and pectoral pulse generator shell (unipolar), and all 3 components (triad). The right ventricular coil was the cathode for the first phase of the biphasic defibrillation waveform. Delivered energy at defibrillation threshold was 11.2 +/- 3.4 J for the lead configuration, 10.1 +/- 5.2 J for the unipolar configuration, and 7.8 +/- 3.6 J for the triad configuration (p <0.01). Leading edge voltage (p <0.01) and shock impedance (p <0.001) were also decreased for the triad configuration compared with the lead or unipolar configurations, whereas peak current was minimized with the unipolar configuration (p <0.01). We conclude that the combination of a dual coil, transvenous lead and an active pectoral shell reduces defibrillation energy requirements compared with either the lead alone or unipolar configuration. Moreover, the defibrillation thresholds were < or =15 J in all patients using the triad lead system.
Collapse
Affiliation(s)
- M R Gold
- Department of Medicine, University of Maryland School of Medicine, Baltimore, USA
| | | | | |
Collapse
|
41
|
Cooper RA, Smith WM, Ideker RE. Internal cardioversion of atrial fibrillation: marked reduction in defibrillation threshold with dual current pathways. Circulation 1997; 96:2693-700. [PMID: 9355911 DOI: 10.1161/01.cir.96.8.2693] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND The ultimate acceptance of a fully automatic atrial defibrillator will depend on the reduction of pain to acceptable levels, requiring a marked decrease in defibrillation thresholds. The purpose of this study was to determine whether atrial defibrillation thresholds can be reduced by sequential shocks delivered through two current pathways. METHODS AND RESULTS Sustained atrial fibrillation was induced with rapid atrial pacing in 12 adult sheep. Defibrillation electrodes were positioned in the right atrial appendage (RAap), distal coronary sinus (DCS), proximal coronary sinus (CSos), main/left pulmonary artery junction (PA), and right ventricular apex (RV). Single-capacitor biphasic waveforms (3/1 ms) were delivered through combinations of these electrodes. Probability-of-success curves were determined for single shocks with a single current pathway and sequential shocks with either single- or dual current pathways. The ED50 for delivered energy for the dual current pathway RAap to DCS then CSos to PA was 0.36+/-0.13 J, which was significantly lower than the ED50 of the standard single current pathway RAap to DCS (1.31+/-0.3 J) and was significantly lower than all other configurations tested. CONCLUSIONS Internal atrial defibrillation thresholds can be markedly reduced with two sequential biphasic shocks delivered over two current pathways compared with the standard single shock delivered over a single current pathway or with sequential shocks delivered over a single current pathway.
Collapse
Affiliation(s)
- R A Cooper
- Department of Medicine, The University of Alabama at Birmingham Medical Center, 35294-0019, USA.
| | | | | |
Collapse
|
42
|
Markewitz A, Kaulbach H, Mattke S, Müller D, Bernutz C, Hoffmann E, Weinhold C, Steinbeck G, Reichart B. Influence of anodal electrode position on transvenous defibrillation efficacy in humans: a prospective randomized comparison. Pacing Clin Electrophysiol 1997; 20:2193-9. [PMID: 9309743 DOI: 10.1111/j.1540-8159.1997.tb04236.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Nonthoracotomy lead systems for implantable cardioverter defibrillators (ICDs) have reduced operative mortality and morbidity as compared to epicardial lead systems but are usually associated with higher defibrillation thresholds (DFTs). The purpose of this prospective randomized trial was to investigate if the second defibrillation electrode in the left subclavian vein can increase defibrillation efficacy and decrease DFT as compared to the superior vena cava (SVC) position in nonthoracotomy lead systems for ICDs. Seventeen patients (mean age: 49.9 +/- 11.3 years, mean ejection fraction: 46.1% +/- 15.8%) were implanted with an investigational unipolar electrode (Medtronic 13001) used as the defibrillation anode. DFT testing was started in the SVC (n = 10, group A) or the left subclavian vein (n = 7, group B), and repeated in the alternative position starting at the DFT of the initial position. Fifteen patients were eligible for analysis (group A: n = 9, group B: n = 6). With the electrode in the SVC, ventricular fibrillation could be successfully terminated in 9 out of 15 patients (60%). In the left subclavian vein the success rate was 100% (P < 0.01). Mean DFT in the SVC was 13.0 +/- 5.2 J and in the left subclavian vein 10.2 +/- 4.9 J. DFTs in the left subclavian vein were either lower (group A: n = 5/9, group B: n = 5/6) or equal to the results in the SVC position (P < 0.001). Thus, the left subclavian vein appears to be a superior alternative for positioning of the defibrillation anode as compared to the SVC for nonthoracotomy lead systems using two separate leads.
Collapse
Affiliation(s)
- A Markewitz
- Department of Cardiac Surgery, Ludwig-Maximilians-University, Grosshadern Hospital, Munich, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
43
|
Schimpf PH, Wang Y, Haynor DR, Kim Y. Sensitivity of transvenous defibrillation models to adaptive mesh density and resolution: the potential for interactive solution times. Int J Med Inform 1997; 45:193-207. [PMID: 9291031 DOI: 10.1016/s1386-5056(97)00030-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The voltage gradients induced in ventricular myocardium by an electric shock have been shown to correlate to the probability of the shock producing a successful defibrillation. Finite element modeling is one method for computing these voltage gradients, although the meshing of complex biomedical domains is difficult on a patient-specific basis. We recently described an adaptive algorithm that automates the generation of finite element meshes for complex 3-D domains from bitmapped images. This article examines the sensitivity of the computed distribution of ventricular voltage gradients to the resolution of the images and to the adapted density of the mesh. The results allow us to establish an adaptation stopping criterion and a minimum input image resolution for modeling transvenous defibrillation. The sensitivity to adapted mesh density was analyzed by comparing voltage gradient histograms from successively finer meshes to histograms from a uniform mesh at the maximum possible density. Comparisons were made using the Kolmogorov-Smirnov test with the number of samples required to detect a 5% difference in the histograms at the 0.05 significance level. Adaptation to a global current density error estimate of 5% or less was required in order to achieve acceptance of the null hypothesis that the distributions were the same in all cases. Defibrillation efficacy, however, is predicted from the voltage gradient in the first quartile, and the results suggest that this region of the cumulative histogram converges faster during mesh adaptation than the histogram as a whole. We also compared histograms from models generated from successively finer input images. The histogram of each model was compared with the histogram obtained from the finest possible resolution. In all cases, the null hypothesis of no difference was accepted at resolutions of 2.3 x 2.3 x 3.0 mm. The average time required to build and adapt models to a 5% accuracy at the first quartile at this resolution was 1.8 min. on a common workstation. We believe that this demonstrates a potential for the eventual synthesis of finite element computations into interactive electrode placement tools on a subject-specific basis.
Collapse
Affiliation(s)
- P H Schimpf
- Department of Electrical Engineering, University of Washington, Seattle 98195, USA
| | | | | | | |
Collapse
|
44
|
Kinst TF, Sweeney MO, Lehr JL, Eisenberg SR. Simulated internal defibrillation in humans using an anatomically realistic three-dimensional finite element model of the thorax. J Cardiovasc Electrophysiol 1997; 8:537-47. [PMID: 9160230 DOI: 10.1111/j.1540-8167.1997.tb00822.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
INTRODUCTION Determination of the optimal electrode configuration during implantable cardioverter defibrillator (ICD) implantation remains largely an empirical process. This study investigated the feasibility of using a finite element model of the thorax to predict clinical defibrillation metrics for internal defibrillation in humans. Computed defibrillation metrics from simulations of three common electrode configurations with a monophasic waveform were compared to pooled metrics for similar electrode and waveform configurations reported in humans. METHODS AND RESULTS A three-dimensional finite element model was constructed from CT cross-sections of a human thorax. Myocardial current density distributions for three electrode configurations (epicardial patches, right ventricular [RV] coil/superior vena cava [SVC] coil, RV coil/SVC coil/subcutaneous patch) and a truncated monophasic pulse with a 65% tilt were simulated. Assuming an inexcitability threshold of 25 mA/cm2 (10 V/cm) and a 75% critical mass criterion for successful defibrillation, defibrillation metrics (interelectrode impedance, defibrillation threshold current, voltage, and energy) were calculated for each electrode simulation. Values of these metrics were within 1 SD of sample-size weighted means for the corresponding metrics determined for similar electrode configurations and waveforms reported in human clinical studies. Simulated myocardial current density distributions suggest that variations in current distribution and uniformity partially explain differences in defibrillation energy requirements between electrode configurations. CONCLUSION Anatomically realistic three-dimensional finite element modeling can closely simulate internal defibrillation in humans. This may prove useful for characterizing patient-specific factors that influence clinically relevant properties of current density distributions and defibrillation energy requirements of various ICD electrode configurations.
Collapse
Affiliation(s)
- T F Kinst
- Department of Biomedical Engineering, Boston University, MA 02215, USA
| | | | | | | |
Collapse
|
45
|
Alt E, Schmitt C, Ammer R, Plewan A, Evans F, Pasquantonio J, Ideker T, Lehmann G, Pütter K, Schömig A. Effect of electrode position on outcome of low-energy intracardiac cardioversion of atrial fibrillation. Am J Cardiol 1997; 79:621-5. [PMID: 9068520 DOI: 10.1016/s0002-9149(96)00827-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The aim of this study was to evaluate the new method of low-energy, catheter-based intracardiac cardioversion in patients with chronic atrial fibrillation (AF) and to compare 2 different lead positions. Accordingly, we prospectively studied 80 consecutive patients with chronic AF (9.8 +/- 7.9 months) who were randomly assigned to undergo internal cardioversion either via defibrillation electrodes placed in the right atrium and coronary sinus (coronary sinus group) or via defibrillation electrodes placed in the right atrium and left pulmonary artery (pulmonary artery group). Intracardiac shocks were delivered by an external defibrillator synchronized to the QRS complex. After conversion, all patients were treated orally with sotalol (mean daily dose, 189 +/- 63 mg/day). For conversion to sinus rhythm, the overall mean energy requirement was 5.6 +/- 3.1 J. In the coronary sinus group, cardioversion was achieved in 35 of 38 patients at a mean energy level of 4.1 +/- 2.3 J (range 1.0 to 9.9), and in the pulmonary artery group in 39 of 42 patients with 7.2 +/- 3.1 J (range 2.5 to 14.8). Although there was no difference with regard to success rate, the energy differed significantly between the 2 groups (p < 0.01). Mean lead impedance was 56.4 +/- 7.0 omega and 54.6 +/- 8.5 omega, respectively (p = NS). No serious complications were observed in either lead group. At a mean follow-up of 14.2 +/- 7.0 months, 54% and 56%, respectively, of patients who had been converted successfully remained in sinus rhythm. Thus, low-energy biphasic shocks delivered between the right atrium and coronary sinus or pulmonary artery are equally effective for cardioversion of patients with chronic AF. The energy requirements for conversion from a pulmonary artery electrode position are higher than for the coronary sinus position.
Collapse
Affiliation(s)
- E Alt
- 1. Medizinische Klinik, Klinikum rechts der Isar, Technischen Universitat München, Germany
| | | | | | | | | | | | | | | | | | | |
Collapse
|
46
|
Alt E, Evans F, Wolf PD, Pasquantonio J, Stotts L, Heinz S, Schömig A. Does reducing capacitance have potential for further miniaturisation of implantable defibrillators? Heart 1997; 77:234-7. [PMID: 9093040 PMCID: PMC484688 DOI: 10.1136/hrt.77.3.234] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
OBJECTIVE To determine whether considerably smaller capacitors could replace 125 microF capacitors as the standard for use in implantable defibrillators. METHODS Measured energy, impedance, voltage, and current delivered were compared at defibrillation threshold in 10 mongrel dogs for defibrillation using 75 microF and 125 microF capacitors alternated randomly. Defibrillation was attempted with biphasic shocks of comparable tilt between an endocardial lead in the right ventricular apex and a "dummy" active can of an experimental implantable device placed in the subpectoral position. RESULTS A reduction of capacitor size of 40% was associated with an increase in voltage of 21% and in current of 22%. With a 65% tilt, no significant differences were found between the two capacitances with respect to the impedance or energy required for defibrillation. CONCLUSIONS Multiple advances in electrode material, electrode configuration, shock morphology, and shock polarity have reduced defibrillation energy requirements. Smaller capacitors could be used in implantable cardioverter/defibrillators without a major decrease in effectiveness.
Collapse
Affiliation(s)
- E Alt
- 1 Medizinische Klinik, Klinikum rechts der Isar, Universität, Munich, Germany
| | | | | | | | | | | | | |
Collapse
|
47
|
Pagan-Carlo LA, Birkett CL, Smith RA, Kerber RE. Is there an optimal electrode pad size to maximize intracardiac current in transthoracic defibrillation? Pacing Clin Electrophysiol 1997; 20:283-92. [PMID: 9058865 DOI: 10.1111/j.1540-8159.1997.tb06172.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Achieving defibrillation depends on adequate intracardiac current. The purpose of this study was to determine, in advance of administering shocks which parameters of body habitus can be used to select the electrode size that maximizes intracardiac current in transthoracic defibrillation. We administered direct current shocks to 18 mongrel dogs over a wide range of weight and size (weight 10-30 kg with chest circumferences 44-77 cm) using a damped sine wave defibrillator and self-adhesive electrode pairs of various diameters (4 cm, 5.8 cm, 8 cm and 10 cm), placed on the right and left lateral chest walls. The energy levels used were 50, 100, and 150 J. Intracardiac voltage gradient, a parameter of intracardiac current, was determined in three orthogonal planes using an intramyocardial electrode array placed in the interventricular septum. The relation between intracardiac voltage gradient magnitude magnitude of VG and various parameters (body weight, chest, circumference, chest volume, chest radius, and heart weight divided by chest radius) was determined. The correlation (r) with the smallest P value was between magnitude of VG and the heart weight divided by chest radius (HW/R) (r = 0.71). Intracardiac current was highest at intermediate pad sizes. The electrode pads that maximized magnitude of VG tended to be large for the larger HW/R dogs, and smaller HW/R dogs. In none of the HW/R groups did the largest electrode pads yield the highest intracardiac voltage gradient. We conclude that there is no simple way to determine in advance an electrode pad size that maximizes intracardiac current. The HW/R ratio influences but does not determine intracardiac intracardiac current.
Collapse
|
48
|
Baker JH, Epstein AE, Voshage-Stahl L. A prospective, randomized evaluation of a nonthoracotomy implantable cardioverter defibrillator lead system. Endotak/PRX Investigator Group. Pacing Clin Electrophysiol 1997; 20:72-8. [PMID: 9121974 DOI: 10.1111/j.1540-8159.1997.tb04814.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Nonthoractomy lead systems for ICDs have been developed that obviate the need for a thoracotomy and reduce the morbidity and mortality associated with implantation. However, an adequate DFT cannot be achieved in some patients using transvenous electrodes alone. Thus, a new subcutaneous "array" electrode was designed and tested in a prospective, randomized trial that compared the DFT obtained using monophasic shock waveforms with a single transvenous lead alone that has two defibrillating electrodes, the transvenous lead linked to a subcutaneous/submuscular patch electrode, and the transvenous lead linked to the investigational array electrode. There were 267 patients randomized to one of the three nonthoracotomy ICD lead systems. All had DFTs that met the implantation criterion of < or = 25 J. The resultant study population was 82% male and 18% female, mean age of 63 +/- 11 years. The indication for ICD implantation was monomorphic VT in 70%, VF in 19%, monomorphic VT/VF in 6%, and polymorphic VT in 4% of the patients, respectively. The mean LVEF was 0.33 +/- 0.13. The mean DFT obtained with the transvenous lead alone was 17.5 +/- 4.9 J as compared to 16.9 +/- 5.5 J with the lead linked to a patch electrode (P = NS), and 14.9 +/- 5.6 with the lead linked to the array electrode (array versus lead alone, P = 0.0001; array versus lead/patch, P = 0.007). The results of this investigation suggest that the subcutaneous array may be superior to the standard patch as a subcutaneous electrode to lower the DFT and increase the margin of safety for successful nonthoracotomy defibrillation.
Collapse
Affiliation(s)
- J H Baker
- Department of Medicine, University of Alabama at Birmingham, USA
| | | | | |
Collapse
|
49
|
Abstract
External electrical atrial defibrillation was developed in the early 1960s. Direct current electrical external shocks convert atrial fibrillation to sinus rhythm in the majority of patients. Although much has been learned about the mechanisms of the arrhythmia and those responsible for successful external direct current atrial defibrillation, the technique has remained essentially unchanged since it was first described by Lown and colleagues. Animal and human studies have shown that atrial defibrillation can be terminated by shocks delivered by way of internal electrode catheters. The technique is most effective when biphasic waveform shocks are delivered by way of large surface area electrodes in the right atrium and the coronary sinus. Synchronization of shocks to R waves greater than 500 msec after the previous beat prevents induction of ventricular tachyarrhythmias. Therefore, internal atrial defibrillation provides an effective and safe method for restoring sinus rhythm in patients who fail external direct current cardioversion. The success of the implantable cardioverter-defibrillator and the encouraging safety and efficacy data from studies of internal atrial defibrillation have generated considerable interest in developing an implantable atrial defibrillator. The efficacy of low-energy shocks to terminate the arrhythmia suggests that such a device might be tolerated by patients. Data about the pathogenesis of atrial fibrillation suggest that rapid detection and immediate termination of atrial fibrillation theoretically might prevent recurrence of the arrhythmia. These data support the development of an implantable atrial defibrillator and the initiation of clinical trials to determine its utility.
Collapse
Affiliation(s)
- M D Carlson
- Division of Cardiology, Case Western Reserve University, Cleveland, Ohio, USA
| | | |
Collapse
|
50
|
Venditti FJ, John RM, Hull M, Tofler GH, Shahian DM, Martin DT. Circadian variation in defibrillation energy requirements. Circulation 1996; 94:1607-12. [PMID: 8840851 DOI: 10.1161/01.cir.94.7.1607] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
BACKGROUND Reports have demonstrated a circadian variation in the incidence of acute myocardial infarction, ventricular arrhythmias, and sudden cardiac death. We tested the hypothesis that a similar circadian variation exists for defibrillation energy requirements in humans. METHODS AND RESULTS We reviewed the time of defibrillation threshold (DFT) measurements in 134 patients with implantable cardioverter-defibrillators (ICDs) who underwent 345 DFT measurements. The DFT was determined in 130 patients at implantation, in 121 at a 2 months, and in 94 at 6 months. All patients had nonthoracotomy systems. The morning DFT (8 AM to 12 noon) was 15.1 +/- 1.2 J compared with 13.1 +/- 0.9 J in the midafternoon (12 noon to 4 PM) and 13.0 +/- 0.7 J in the late afternoon (4 to 8 PM), P < .02. In a separate group of 930 patients implanted with an ICD system with date and time stamps for each therapy, we reviewed 1238 episodes of ventricular tachyarrhythmias treated with shock therapy. To corroborate the hypothesis that energy requirements for arrhythmia termination vary during the course of the day, we plotted the failed first shock frequency for all episodes per hour. There was a significant peak in failed first shocks in the morning compared with other time intervals (P = .02). CONCLUSIONS There is a morning peak in DFT and a corresponding morning peak in failed first shock frequency. This morning peak resembles the peaks seen in other cardiac events, specifically sudden cardiac death. These findings have important implications for appropriate ICD function, particularly in patients with marginal DFTs.
Collapse
Affiliation(s)
- F J Venditti
- Section of Cardiovascular Medicine, Lahey-Hitchcock Medical Center, Burlington, Mass 01805, USA
| | | | | | | | | | | |
Collapse
|