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Fuster V, Rydén LE, Cannom DS, Crijns HJ, Curtis AB, Ellenbogen KA, Halperin JL, Kay GN, Le Huezey JY, Lowe JE, Olsson SB, Prystowsky EN, Tamargo JL, Wann LS. 2011 ACCF/AHA/HRS Focused Updates Incorporated Into the ACC/AHA/ESC 2006 Guidelines for the Management of Patients With Atrial Fibrillation. Circulation 2011; 123:e269-367. [PMID: 21382897 DOI: 10.1161/cir.0b013e318214876d] [Citation(s) in RCA: 595] [Impact Index Per Article: 45.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Fuster V, Rydén LE, Cannom DS, Crijns HJ, Curtis AB, Ellenbogen KA, Halperin JL, Kay GN, Le Huezey JY, Lowe JE, Olsson SB, Prystowsky EN, Tamargo JL, Wann LS. 2011 ACCF/AHA/HRS Focused Updates Incorporated Into the ACC/AHA/ESC 2006 Guidelines for the Management of Patients With Atrial Fibrillation. J Am Coll Cardiol 2011; 57:e101-98. [PMID: 21392637 DOI: 10.1016/j.jacc.2010.09.013] [Citation(s) in RCA: 642] [Impact Index Per Article: 49.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Fuster V, Rydén LE, Cannom DS, Crijns HJ, Curtis AB, Ellenbogen KA, Halperin JL, Le Heuzey JY, Kay GN, Lowe JE, Olsson SB, Prystowsky EN, Tamargo JL, Wann S, Smith SC, Jacobs AK, Adams CD, Anderson JL, Antman EM, Halperin JL, Hunt SA, Nishimura R, Ornato JP, Page RL, Riegel B, Priori SG, Blanc JJ, Budaj A, Camm AJ, Dean V, Deckers JW, Despres C, Dickstein K, Lekakis J, McGregor K, Metra M, Morais J, Osterspey A, Tamargo JL, Zamorano JL. ACC/AHA/ESC 2006 Guidelines for the Management of Patients with Atrial Fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients With Atrial Fibrillation): developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society. Circulation 2006; 114:e257-354. [PMID: 16908781 DOI: 10.1161/circulationaha.106.177292] [Citation(s) in RCA: 1381] [Impact Index Per Article: 76.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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White RD, Blackwell TH, Russell JK, Snyder DE, Jorgenson DB. Transthoracic impedance does not affect defibrillation, resuscitation or survival in patients with out-of-hospital cardiac arrest treated with a non-escalating biphasic waveform defibrillator. Resuscitation 2005; 64:63-9. [PMID: 15629557 DOI: 10.1016/j.resuscitation.2004.06.021] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2004] [Revised: 06/23/2004] [Accepted: 06/23/2004] [Indexed: 10/26/2022]
Abstract
OBJECTIVE This is a study of the influence of transthoracic impedance (TTI) on defibrillation, resuscitation and survival in patients with out-of-hospital cardiac arrest (OHCA), treated with a non-escalating impedance-compensating 150 J biphasic waveform defibrillator. METHODS Cardiac arrest data from two EMS systems were analyzed retrospectively. All witnessed arrests from patients who presented with a shockable rhythm and were treated initially by BLS personnel were included (n = 102). For each defibrillation and resuscitation outcome variable, we tested differences in mean TTI for successful versus unsuccessful outcome. The effect of call-to-shock time on overall outcome was also examined. RESULTS Initial shocks defibrillated 90% [83-95%] (95% confidence interval) of patients. Cumulative success with two shocks was 98% [93-100%] and with three shocks was 99% [95-100%]. TTI averaged 90 +/- 23 Omega. First-shock success, cumulative success through two shocks and cumulative success through the first-shock series were unrelated to TTI, as were BLS ROSC, pre-hospital ROSC, hospital admission and discharge. In contrast and consistent with previous findings, call-to-shock time was highly predictive of survival. CONCLUSIONS High impedance patients were defibrillated by the biphasic waveform used in this study at high rates with a fixed energy of 150 J and without energy escalation. Rapid defibrillation rather than differences in patient impedance accounts for resuscitation success.
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Affiliation(s)
- Roger D White
- Department of Anesthesiology, The Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA.
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White RD, Blackwell TH, Russell JK, Jorgenson DB. Body weight does not affect defibrillation, resuscitation, or survival in patients with out-of-hospital cardiac arrest treated with a nonescalating biphasic waveform defibrillator. Crit Care Med 2004; 32:S387-92. [PMID: 15508666 DOI: 10.1097/01.ccm.0000139460.25406.78] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND This is a study of the influence of body weight on defibrillation, resuscitation, and survival in patients with out-of-hospital cardiac arrest treated with a nonescalating impedance-compensating 150-J biphasic waveform defibrillator. METHODS Cardiac arrest data from Rochester, MN, emergency medical services over a 6-yr period was retrospectively analyzed. Patient weight data were available for 62 of the 68 patients who were treated initially by basic life support personnel and who presented with a shockable rhythm. For each defibrillation and resuscitation outcome variable, we tested for differences in body weight for successful vs. unsuccessful outcome. RESULTS Initial shocks defibrillated 92% (83% to 97%) of patients. Cumulative success with two shocks was 98% (confidence interval, 92% to 100%) and with three shocks was 100% (confidence interval, 95% to 100%). The mean shock impedance was 90 +/- 21 ohms. The average body weight was 84 +/- 17 kg (minimum, 53 kg; maximum, 135 kg) and was normally distributed. Based on the body mass index for 46 patients, approximately 41% were classified as overweight (body mass index, > or = 25), 24% obese (body mass index, > or = 30), and 4% extremely obese (body mass index, > or = 40). The remaining 31% were classified as normal or underweight. First-shock success, cumulative success through two shocks, and cumulative success through the first-shock series were unrelated to body weight, as were basic life support restoration of spontaneous circulation, prehospital restoration of spontaneous circulation, hospital admission, and discharge. CONCLUSIONS Overweight patients were defibrillated by the biphasic waveform used in this study at high rates, with a fixed energy of 150 J, and without energy escalation.
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Affiliation(s)
- Roger D White
- The Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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Jones JL, Snyder DE, Morgan C. Predictions from misleading pig model are potentially harmful to humans. Resuscitation 2003; 59:365-7; author reply 367-71. [PMID: 14659607 DOI: 10.1016/j.resuscitation.2003.07.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Fuster V, Rydén LE, Asinger RW, Cannom DS, Crijns HJ, Frye RL, Halperin JL, Kay G, Klein WW, Lévy S, McNamara RL, Prystowsky EN, Wann L, Wyse D, Gibbons RJ, Antman EM, Alpert JS, Faxon DP, Fuster V, Gregoratos G, Hiratzka LF, Jacobs AK, Russell RO, Smith SC, Klein WW, Alonso-Garcia A, Blomström-Lundqvist C, De Backer G, Flather M, Hradec J, Oto A, Parkhomenko A, Silber S, Torbicki A. ACC/AHA/ESC guidelines for the management of patients with atrial fibrillation31This document was approved by the American College of Cardiology Board of Trustees in August 2001, the American Heart Association Science Advisory and Coordinating Committee in August 2001, and the European Society of Cardiology Board and Committee for Practice Guidelines and Policy Conferences in August 2001.32When citing this document, the American College of Cardiology, the American Heart Association, and the European Society of Cardiology would appreciate the following citation format: Fuster V, Rydén LE, Asinger RW, Cannom DS, Crijns HJ, Frye RL, Halperin JL, Kay GN, Klein WW, Lévy S, McNamara RL, Prystowsky EN, Wann LS, Wyse DG. ACC/AHA/ESC guidelines for the management of patients with atrial fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines and Policy Conferences (Committee to Develop Guidelines for the Management of Patients With Atrial Fibrillation). J Am Coll Cardiol 2001;38:XX-XX.33This document is available on the World Wide Web sites of the American College of Cardiology (www.acc.org), the American Heart Association (www.americanheart.org), the European Society of Cardiology (www.escardio.org), and the North American Society of Pacing and Electrophysiology (www.naspe.org). Single reprints of this document (the complete Guidelines) to be published in the mid-October issue of the European Heart Journal are available by calling +44.207.424.4200 or +44.207.424.4389, faxing +44.207.424.4433, or writing Harcourt Publishers Ltd, European Heart Journal, ESC Guidelines – Reprints, 32 Jamestown Road, London, NW1 7BY, United Kingdom. Single reprints of the shorter version (Executive Summary and Summary of Recommendations) published in the October issue of the Journal of the American College of Cardiology and the October issue of Circulation, are available for $5.00 each by calling 800-253-4636 (US only) or by writing the Resource Center, American College of Cardiology, 9111 Old Georgetown Road, Bethesda, Maryland 20814. To purchase bulk reprints specify version and reprint number (Executive Summary 71-0208; full text 71-0209) up to 999 copies, call 800-611-6083 (US only) or fax 413-665-2671; 1000 or more copies, call 214-706-1466, fax 214-691-6342; or E-mail: pubauth@heart.org. J Am Coll Cardiol 2001. [DOI: 10.1016/s0735-1097(01)01586-8] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Schneider T, Martens PR, Paschen H, Kuisma M, Wolcke B, Gliner BE, Russell JK, Weaver WD, Bossaert L, Chamberlain D. Multicenter, randomized, controlled trial of 150-J biphasic shocks compared with 200- to 360-J monophasic shocks in the resuscitation of out-of-hospital cardiac arrest victims. Optimized Response to Cardiac Arrest (ORCA) Investigators. Circulation 2000; 102:1780-7. [PMID: 11023932 DOI: 10.1161/01.cir.102.15.1780] [Citation(s) in RCA: 176] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND In the present study, we compared an automatic external defibrillator (AED) that delivers 150-J biphasic shocks with traditional high-energy (200- to 360-J) monophasic AEDs. METHODS AND RESULTS AEDs were prospectively randomized according to defibrillation waveform on a daily basis in 4 emergency medical services systems. Defibrillation efficacy, survival to hospital admission and discharge, return of spontaneous circulation, and neurological status at discharge (cerebral performance category) were compared. Of 338 patients with out-of-hospital cardiac arrest, 115 had a cardiac etiology, presented with ventricular fibrillation, and were shocked with an AED. The time from the emergency call to the first shock was 8.9+/-3.0 (mean+/-SD) minutes. CONCLUSIONS The 150-J biphasic waveform defibrillated at higher rates, resulting in more patients who achieved a return of spontaneous circulation. Although survival rates to hospital admission and discharge did not differ, discharged patients who had been resuscitated with biphasic shocks were more likely to have good cerebral performance.
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Affiliation(s)
- T Schneider
- Johannes Gutenberg-Universitaet, Mainz, Germany
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Gliner BE, White RD. Electrocardiographic evaluation of defibrillation shocks delivered to out-of-hospital sudden cardiac arrest patients. Resuscitation 1999; 41:133-44. [PMID: 10488935 DOI: 10.1016/s0300-9572(99)00040-4] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
OBJECTIVE Following out-of-hospital defibrillation attempts, electrocardiographic instability challenges accurate assessment of defibrillation efficacy and post-shock rhythm. Presently, there is no precise definition of defibrillation efficacy in the out-of-hospital setting that is consistently used. The objective of this study was to characterize out-of-hospital cardiac arrest rhythms following low-energy biphasic and high-energy monophasic shocks in order to precisely define defibrillation efficacy and establish uniform criteria for the evaluation of shock performance. METHODS Automatic external defibrillators (AEDs) delivering 150 J impedance-compensating biphasic or 200-360 J monophasic damped sine waveform shocks were observed in a combined police and paramedic program. ECGs from 29 biphasic patients and 87 monophasic patients were classified as organized, asystole or VF at post-shock times of 3, 5, 10, 20 and 60 s. RESULTS Post-shock time (P<0.0001) and shock waveform type (P = 0.02) affected the classification of post-shock rhythm. At each analysis time, there were more patients in VF following high-energy monophasic shocks than following 150 J biphasic shocks (P<0.0001). The percentage of patients in VF increased with post-shock time. The rate of VF recurrence was not a function of shock type, indicating that refibrillation is largely a function of the patient's underlying cardiac disease. CONCLUSION Defibrillation should uniformly be defined as termination of VF for a minimum of 5-s after shock delivery. Rhythms should be reported at 5-s after shock delivery to assess early effects of the defibrillation shock and at 60-s after shock delivery to assess the interaction of the defibrillation therapy and factors such as post-shock myocardial dysfunction and the patient's underlying cardiac disease.
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Poole JE, White RD, Kanz KG, Hengstenberg F, Jarrard GT, Robinson JC, Santana V, McKenas DK, Rich N, Rosas S, Merritt S, Magnotto L, Gallagher JV, Gliner BE, Jorgenson DB, Morgan CB, Dillon SM, Kronmal RA, Bardy GH. Low-energy impedance-compensating biphasic waveforms terminate ventricular fibrillation at high rates in victims of out-of-hospital cardiac arrest. LIFE Investigators. J Cardiovasc Electrophysiol 1997; 8:1373-85. [PMID: 9436775 DOI: 10.1111/j.1540-8167.1997.tb01034.x] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
INTRODUCTION New automatic external defibrillators (AEDs), which are smaller, lighter, easier to use, and less costly make the goal of widespread AED deployment and early defibrillation for out-of-hospital cardiac arrest feasible. The objective of this study was to observe the performance of a low-energy impedance-compensating biphasic waveform in the out-of-hospital setting on 100 consecutive victims of sudden cardiac arrest. METHODS AND RESULTS AEDs incorporating a 150-J impedance-compensating biphasic waveform were used by 12 EMS systems. Data were obtained from the AED PC card reporting system. Defibrillation was defined as conversion to an organized rhythm or to asystole. Endpoints included: defibrillation efficacy for ventricular fibrillation (VF); restoration of an organized rhythm at the time of patient transfer to an advanced life support (ALS) team or to the emergency department (ED); and time from AED power-on to first defibrillation. The AED correctly identified 44 of 100 patients presenting in VF as requiring a shock (100% sensitivity) and 56 of 100 patients not in VF as not requiring a shock (100% specificity). The time from 911 call to first shock delivery averaged 8.1 +/- 3.0 minutes. A single 150-J biphasic shock defibrillated the initial VF episode in 39 of 44 (89%) patients. The average time from power-on to first defibrillation was 25 +/- 17 seconds. At patient transfer to ALS or ED care, an organized rhythm was present in 34 of 44 (77%) patients presenting with VF. Asystole was present in 7 (16%) and VF in 3 (7%). CONCLUSIONS Low-energy impedance-compensating biphasic waveforms terminate long-duration VF at high rates in out-of-hospital cardiac arrest. Use of this waveform allows AED device characteristics consistent with widespread AED deployment and early defibrillation.
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Affiliation(s)
- J E Poole
- The University of Washington, Seattle 98195, USA.
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Bardy GH, Marchlinski FE, Sharma AD, Worley SJ, Luceri RM, Yee R, Halperin BD, Fellows CL, Ahern TS, Chilson DA, Packer DL, Wilber DJ, Mattioni TA, Reddy R, Kronmal RA, Lazzara R. Multicenter comparison of truncated biphasic shocks and standard damped sine wave monophasic shocks for transthoracic ventricular defibrillation. Transthoracic Investigators. Circulation 1996; 94:2507-14. [PMID: 8921795 DOI: 10.1161/01.cir.94.10.2507] [Citation(s) in RCA: 126] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND The most important factor for improving out-of-hospital ventricular fibrillation survival rates is early defibrillation. This can be achieved if small, lightweight, inexpensive automatic external defibrillators are widely disseminated. Because automatic external defibrillator size and cost are directly affected by defibrillation waveform shape and because of the favorable experience with truncated biphasic waveforms in implantable cardioverter-defibrillators, we compared the efficacy of a truncated biphasic waveform with that of a standard damped sine monophasic waveform for transthoracic defibrillation. METHODS AND RESULTS The principal goal of this multicenter, prospective, randomized, blinded study was to compare the first-shock transthoracic defibrillation efficacy of a 130-J truncated biphasic waveform with that of a standard 200-J monophasic damped sine wave pulse using anterior thoracic pads in the course of implantable cardioverter-defibrillator testing. Pad-pad ECGs were also examined after transthoracic defibrillation. After the elimination of data for 24 patients who did not meet all protocol criteria, the results from 294 patients were analyzed. The 130-J truncated biphasic pulse and the 200-J damped sine wave monophasic pulse resulted in first-shock efficacy rates of 86% and 86%, respectively (P = .97). ST-segment levels measured 10 seconds after the shock in 151 patients in sinus rhythm were -0.26 +/- 1.58 and -1.86 +/- 1.93 mm for the 130- and 200-J shocks, respectively (P < .0001). CONCLUSIONS We found that 130-J biphasic truncated transthoracic shocks defibrillate as well as the 200-J monophasic damped sine wave shocks that are traditionally used in standard transthoracic defibrillators and result in fewer ECG abnormalities after the shock.
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Affiliation(s)
- G H Bardy
- Department of Medicine, University of Washington (Seattle), USA.
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Functional damage to the heart caused by monophasic and biphasic defibrillation waveforms. Bull Exp Biol Med 1993. [DOI: 10.1007/bf00785503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Lehr JL, Ramirez IF, Karlon WJ, Eisenberg SR. Test of four defibrillation dosing strategies using a two-dimensional finite-element model. Med Biol Eng Comput 1992; 30:621-8. [PMID: 1297017 DOI: 10.1007/bf02446794] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The most widely used defibrillation dosing strategy is that adopted by the American Heart Association in 1986. However, several alternative dosing strategies have been proposed to match delivered energy to the individual requirements of defibrillation subjects. In this study, two-dimensional finite element methods are used to investigate the performance of four of these dosing strategies applied to three thoracic models representative of men and women of different thoracic aspect ratios. From the resulting current density distributions, the relative effectiveness of the following dosing strategies are evaluated and compared: constant current; current proportional to body weight; constant energy; energy proportional to body weight. Our results show that the strategy of applying current proportional to subject body weight with a current dose of 0.58 A kg-1 was able to defibrillate all three subjects with only minimal overexposure of any one of them. None of the other dosing strategies examined could be made to successfully defibrillate all three subjects without significantly overexposing at least one.
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Affiliation(s)
- J L Lehr
- Department of Biomedical Engineering, Brigham & Women's Hospital, Boston, MA 02115
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Johnson CR, MacLeod RS, Ershler PR. A computer model for the study of electrical current flow in the human thorax. Comput Biol Med 1992; 22:305-23. [PMID: 1424577 DOI: 10.1016/0010-4825(92)90020-n] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Electrocardiography has played an important role in the detection and characterization of heart function, both in normal and abnormal states. In this paper we present an inhomogeneous, anisotropic computer model of the human thorax for use in electrocardiography with emphasis on the calculation of transthoracic potential and current distributions. Knowledge of the current pathways in the thorax has many applications in electrocardiography and has direct utility in studies pertaining to cardiac defibrillation, forward and inverse problems, impedance tomography, and electrode placement in electrocardiography.
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Affiliation(s)
- C R Johnson
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City 84112
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Dillon SM. Optical recordings in the rabbit heart show that defibrillation strength shocks prolong the duration of depolarization and the refractory period. Circ Res 1991; 69:842-56. [PMID: 1873877 DOI: 10.1161/01.res.69.3.842] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The present data were obtained using the technique of optical recording with the voltage-sensitive dye WW781. This technique, unlike electrical methods, was able to provide uninterrupted recordings free of artifacts during defibrillation shocks. Optical recordings were made from sites on the ventricular epicardium of perfused rabbit hearts during electrical pacing. Continuous recordings of the electrophysiological responses of an intact heart to defibrillation threshold-strength shocks were made. It was shown that these shocks were able to stimulate normal-appearing action potentials in nonrefractory myocardium. A new and unexpected finding was that defibrillation threshold-strength shocks were also able to evoke a sustained, depolarizing response from myocardium already undergoing an action potential. This prolonged the time that the myocardium remained in the depolarized state. Prolongation of the depolarized state was accompanied by an equal prolongation of the refractory period. There was no indication that this depolarizing shock response was due to damage of the myocardium by the shock, to heterogeneous electrical responses in the optical recording area, or to the methods used in this study. It is hypothesized that these shocks were able to elicit a new action potential in already depolarized myocardium by hyperpolarizing portions of the myocardium's cellular membranes and, in so doing, to reactivate the fast sodium current. This effect, if prevalent in a fibrillating ventricle, could play a role in the defribillation process by effectively resynchronizing electrical activity.
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Affiliation(s)
- S M Dillon
- Department of Pharmacology, College of Physicians and Surgeons, Columbia University, New York, NY 10032
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Merillat JC, Lakatta EG, Hano O, Guarnieri T. Role of calcium and the calcium channel in the initiation and maintenance of ventricular fibrillation. Circ Res 1990; 67:1115-23. [PMID: 2171799 DOI: 10.1161/01.res.67.5.1115] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The cellular events during the initiation and maintenance of ventricular fibrillation (VF) are poorly understood. We developed a nonischemic, isolated, perfused rabbit Langendorff preparation in which sustained VF could be induced by alternating current (AC) and which allowed changes in perfusate composition. We also used Na(+)-K+ pump inhibition (10 microM ouabain or K(+)-free perfusate) to induce VF. AC stimulation or Na(+)-K+ pump inhibition always initiated VF. Calcium channel blockade by verapamil or nitrendipine uniformly inhibited the initiation of VF in both models. During Na(+)-K+ pump inhibition, 1) VF was prevented by calcium channel blockade, despite evidence of Ca2+ overload, and 2) abolition of spontaneous sarcoplasmic reticulum-generated cytosolic Ca2+ oscillations by ryanodine or Na+ channel blockade with tetrodotoxin did not prevent VF initiation. Lowering extracellular [Ca2+] to 80 microM uniformly prevented the initiation of VF due to Na(+)-K+ pump inhibition but not that due to AC stimulation. VF maintenance also was studied using 1) reduction in perfusate [Ca2+], 2) blockade of Ca2+ channels, or 3) electrical defibrillation. Decreasing the perfusate [Ca2+] to 80 microM resulted in defibrillation during VF whether induced by AC or Na(+)-K+ pump inhibition. Verapamil or nitrendipine also resulted in defibrillation regardless of the initiation method. Electrical defibrillation was successful only in AC-induced VF. The results demonstrate that VF can be initiated and maintained in a nonischemic rabbit Langendorff preparation. The data suggest that increases in slow channel Ca2+ flux, as opposed to increases in cytosolic Ca2+ per se, were necessary for the initiation and maintenance of VF. The data, however, do not exclude an important role for cytosolic Ca2+ in the modulation of VF.
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Affiliation(s)
- J C Merillat
- Johns Hopkins University School of Medicine, National Institute on Aging, Baltimore, Md
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Abstract
Early electrical therapy for patients with ventricular fibrillation and ventricular tachycardia can result in a significant increase of lives saved from sudden cardiac death. Rapid defibrillation has become a goal of prehospital and emergency department cardiac care, and the use of automatic external defibrillators can aid in reaching this objective. The history, mechanics, and implications of automatic external defibrillators are presented.
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Affiliation(s)
- J J Bocka
- Department of Emergency Medicine, William Beaumont Hospital, Royal Oak, Michigan 48072
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Ramirez IF, Eisenberg SR, Lehr JL, Schoen FJ. Effects of cardiac configuration, paddle placement and paddle size on defibrillation current distribution: a finite-element model. Med Biol Eng Comput 1989. [DOI: 10.1007/bf02441640] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Van Gelder IC, Crijns HJ, Van Gilst WH, De Langen CD, Van Wijk LM, Lie KI. Effects of flecainide on the atrial defibrillation threshold. Am J Cardiol 1989; 63:112-4. [PMID: 2491771 DOI: 10.1016/0002-9149(89)91090-4] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- I C Van Gelder
- Department of Cardiology, University Hospital Groningen, the Netherlands
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Arad M, Rogel S, Mahler Y, Uretzky G. The effect of heart rate on the termination of electrically induced ventricular fibrillation in the isolated perfused rat heart. Basic Res Cardiol 1988; 83:678-86. [PMID: 3223882 DOI: 10.1007/bf01906963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Ventricular fibrillation (VF) which is normally sustained in large animals and humans, is transient in small animals. The purpose of the present study was to evaluate the possible effect of changing cardiac rate on spontaneous ventricular defibrillation. In isolated perfused rat heart, VF was electrically induced during normal spontaneous rhythm of the heart at normal rate and at various ventricular pacing rates. It was found that: 1) Electrically induced VF in isolated perfused, non-ischemic rat heart spontaneously terminated in 88% of the hearts; 2) Ventricular pacing rhythm of spontaneous rate plus 10% caused VF to be sustained in 26% of the hearts (which defibrillated spontaneously during normal rates); 3) Ventricular pacing at 200% of the basic rate led to sustained VF in about half the VF episodes (14 out of 33, p less than 0.005). In the remainder, which defibrillated spontaneously, a sustained VF could be achieved by further increase in ventricular pacing rate; 4) Slow pacing rate, as a result of the surgical production of atrioventricular (A-V) block, enhanced the probability of spontaneous defibrillation (21 of 21 episodes after slow pacing vs 24 of 34 episodes following pacing at previous normal sinus rhythm, p less than 0.05). Selective modulation of conduction velocity, refractory period or both, achieved by changes in ventricular pacing rate was assumed to play an important role in determining whether electrically-induced VF would be transient or sustained.
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Affiliation(s)
- M Arad
- Joseph Lunenfeld Cardiac Surgery Research Center, Department of Medical Engineering, Hadassah University Hospital, Jerusalem, Israel
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Abstract
This paper discusses the development of theoretical models of heart defibrillation by a bipolar impulse. These are based on theoretical mechanisms as well as our results obtained in a series of fibrillation/defibrillation experiments carried out in anesthetized mongrel dogs. The procedures for fibrillation and defibrillation have been previously described. During the experiments, blood pressure, ECG, and ventricular wall contraction strength are continuously recorded. The methods of recording have been previously described.
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Affiliation(s)
- A M Chernysh
- Department of Physics, First Moscow Medical Institute, U.S.S.R
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23
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Machin JW, Brownhill J, Furness A. Thoracic impedance of adult males during defibrillation--a curious discrepancy. Med Biol Eng Comput 1987; 25:679-83. [PMID: 3505308 DOI: 10.1007/bf02447339] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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24
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Wilson RF, Sirna S, White CW, Kerber RE. Defibrillation of high-risk patients during coronary angiography using self-adhesive, preapplied electrode pads. Am J Cardiol 1987; 60:380-2. [PMID: 3618500 DOI: 10.1016/0002-9149(87)90252-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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25
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Moak JP, Friedman RA, Garson A. Electrical ablation of atrial muscle. II. Early and late electrophysiologic observations in canine atria. Am Heart J 1987; 113:1404-13. [PMID: 3591610 DOI: 10.1016/0002-8703(87)90655-7] [Citation(s) in RCA: 10] [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: 01/06/2023]
Abstract
Electrical ablation techniques (ECT) have had limited success in achieving control of arrhythmias originating in the right atrial free wall (RAFW). To ascertain determinants for successful ECT, we studied the clinical and cellular electrophysiologic effects of electrical ablation of the RAFW. After performing electrical ablation of the RAFW in 12 beagle puppies, the following studies were performed: Holter monitoring first 24 hours (eight puppies), and 11 weeks later (four puppies); clinical electrophysiologic study (four puppies); and microelectrode study (ME) (eight puppies). Arrhythmias (AR) and conduction disturbances (CD) frequently occurred immediately following ECT: ventricular tachycardia (VT) (seven puppies), junctional tachycardia (one puppy), and asystole or complete AV block (AVB) (four puppies). Holter monitoring during the first 24 hours after ECT revealed VT (four puppies), frequent ventricular premature depolarizations (one puppy), and type 2 second-degree AVB (four puppies). AR were rarely seen late after ECT. During clinical EP study 11 weeks after ablation, atrial fibrillation was induced in three of four puppies; none had AR prior to ECT. Early ME study revealed a nonhomogeneous atrial infarct--a central zone of "dead" cells surrounded by peripheral islands of depressed cellular activity. Cells with normal action potential characteristics were noted in between. We conclude that Electrical ablation of the RAFW is associated with a high incidence of early AR and CD. Because of the nonhomogeneous nature of tissue injury produced during ECT, careful atrial mapping is critically important. Local regions of conduction delay and block may provide a substrate for the late development of atrial arrhythmias.
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Davy JM, Fain ES, Dorian P, Winkle RA. The relationship between successful defibrillation and delivered energy in open-chest dogs: reappraisal of the "defibrillation threshold" concept. Am Heart J 1987; 113:77-84. [PMID: 3799444 DOI: 10.1016/0002-8703(87)90012-3] [Citation(s) in RCA: 197] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The traditional assessment of the energy required for successful ventricular defibrillation involves the measurement of a "defibrillation threshold" (DFT), implying a clear-cut distinction between effective and ineffective energies. We examined the relationship between delivered energy and the likelihood of successful defibrillation in 10 open-chest pentobarbital anesthetized dogs, with the use of an internal spring/patch electrode system. An initial DFT was determined by decreasing the energy discharged until a failure first occurred (10.3 +/- 3.4 J). Six energy levels in 1 to 2 J increments were then selected surrounding this value and each was administered eight times in balanced random order (total 48 trials). The relationship between energy and percent success in defibrillation exhibited a shallow slope, with a gradual increase in success from 0% to 100% over several energy increments. The initial DFTs showed actual success rates varying from 25% to 87.5% (mean 71 +/- 26%). The results were fitted to a sigmoidal dose-response curve by logistic regression analysis and the energy associated with 50% success (E50) and 80% success (E80) was determined, as no single value for DFT could be defined in any animal. In 12 other dogs, a defibrillation curve was similarly constructed at baseline and was repeated after 90 minutes. No significant change in E50 (5.0 +/- 2.1 J vs 5.2 +/- 2.7 J) or E80 (6.3 +/- 2.5 J vs 6.6 +/- 3.2 J) was observed.(ABSTRACT TRUNCATED AT 250 WORDS)
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27
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Lawrence JH, Brin KP, Halperin HR, Platia EV, Tsitlik JE, Levine JH, Guarnieri T. The characterization of human transmyocardial impedance during implantation of the automatic internal cardioverter defibrillator. Pacing Clin Electrophysiol 1986; 9:745-55. [PMID: 2429282 DOI: 10.1111/j.1540-8159.1986.tb05424.x] [Citation(s) in RCA: 20] [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: 12/31/2022]
Abstract
We set out to determine in a prospective fashion the characteristics of energy delivery related to defibrillation in a population of patients receiving the AICD. Specifically, we examined the characteristics of the delivered current, transmyocardial voltage, and transmyocardial impedance. Secondly, we determined the relationship between the energy delivered, the impedance encountered and the defibrillation threshold. Since the AICD will deliver a succession of shocks if the initial shock does not cardiovert, the effects of consecutive shocks at different energy levels on the transmyocardial impedance were also assessed.
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Chen PS, Shibata N, Dixon EG, Wolf PD, Danieley ND, Sweeney MB, Smith WM, Ideker RE. Activation during ventricular defibrillation in open-chest dogs. Evidence of complete cessation and regeneration of ventricular fibrillation after unsuccessful shocks. J Clin Invest 1986; 77:810-23. [PMID: 3949979 PMCID: PMC423467 DOI: 10.1172/jci112378] [Citation(s) in RCA: 217] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
To test the hypothesis that a defibrillation shock is unsuccessful because it fails to annihilate activation fronts within a critical mass of myocardium, we recorded epicardial and transmural activation in 11 open-chest dogs during electrically induced ventricular fibrillation (VF). Shocks of 1-30 J were delivered through defibrillation electrodes on the left ventricular apex and right atrium. Simultaneous recordings were made from septal, intramural, and epicardial electrodes in various combinations. Immediately after all 104 unsuccessful and 116 successful defibrillation shocks, an isoelectric interval much longer than that observed during preshock VF occurred. During this time no epicardial, septal, or intramural activations were observed. This isoelectric window averaged 64 +/- 22 ms after unsuccessful defibrillation and 339 +/- 292 ms after successful defibrillation (P less than 0.02). After the isoelectric window of unsuccessful shocks, earliest activation was recorded from the base of the ventricles, which was the area farthest from the apical defibrillation electrode. Activation was synchronized for one or two cycles following unsuccessful shocks, after which VF regenerated. Thus, after both successful and unsuccessful defibrillation with epicardial shocks of greater than or equal to 1 J, an isoelectric window occurs during which no activation fronts are present; the postshock isoelectric window is shorter for unsuccessful than for successful defibrillation; unsuccessful shocks transiently synchronize activation before fibrillation regenerates; activation leading to the regeneration of VF after the isoelectric window for unsuccessful shocks originates in areas away from the defibrillation electrodes. The isoelectric window does not support the hypothesis that defibrillation fails solely because activation fronts are not halted within a critical mass of myocardium. Rather, unsuccessful epicardial shocks of greater than or equal to 1 J halt all activation fronts after which VF regenerates.
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Geuze RH, de Feijter PJ. Evaluation of transthoracic countershock with initial energy levels up to 200 J in a coronary care unit. J Electrocardiol 1985; 18:251-8. [PMID: 4031728 DOI: 10.1016/s0022-0736(85)80049-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In a five year prospective study, transthoracic countershock of patients in the coronary care unit was evaluated with respect to efficacy, transthoracic resistance and arrhythmias. Those patients dying within 12 hours of the recorded event are referred to as agonal patients. Atrial arrhythmias were generally first treated with quinidine or disopyramide and/or a digitalis preparation. Patients with coronary heart disease were treated with lidocaine, disopyramide, or verapamil when there was time for appropriate diagnosis. The efficacy of the first shock with an energy level between 50 J and 200 J in non-agonal patients was: for atrial fibrillation, 44% (N = 34), and between 83% and 93% for tachycardias and ventricular fibrillation. The cumulative efficacy of two shocks with energy levels between 50 J and 200 J was: in atrial fibrillation 53% and others between 90% and 96%. In agonal patients with ventricular fibrillation and acute myocardial infarction the efficacy of one shock of 100-150 J was 39% and two shocks of 100-200 J, 69% (N = 13). No correlation was found between the transthoracic resistance and parameters such as body-weight, length or thorax-circumference, indicating that these should not be taken into account in the choice of the energy level for countershock. In non-agonal patients without coronary heart disease arrhythmias due to countershock increased in duration when the energy of the countershock increased (p less than 0.01, N = 39). It is concluded that the initial stored energy for defibrillation and cardioversion of nonagonal patients in a coronary care unit may be limited to 200 J (160 J delivered energy), even with atrial fibrillation after drug therapy in which case an initial energy level of 200 J seems more appropriate.
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Lake CL, Sellers TD, Nolan SP, Crosby IK, Wellons HA, Crampton RS. Low-energy defibrillation: safe and effective. Am J Emerg Med 1985; 3:104-7. [PMID: 3970764 DOI: 10.1016/0735-6757(85)90030-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
During cardiopulmonary bypass, 150 cardiac surgical patients were prospectively evaluated for the number, energy, current, and success rates of direct current (DC) shocks required to terminate reperfusion ventricular fibrillation (1 degree) or ventricular fibrillation occurring subsequent to a nonfibrillatory reperfusion rhythm (2 degrees). Thirty-one percent of 1-J shocks and 58% of 2.5-J shocks defibrillated. Above 2.5 J, the defibrillation success rate reached a plateau of 50-60%. Myocardial resistance decreased significantly after the first shock but remained stable during subsequent shocks. Lower defibrillating currents and myocardial resistances than had been previously reported were observed. The feasibility of low-energy defibrillation during cardiopulmonary bypass was therefore documented.
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31
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Kerber RE, McPherson D, Charbonnier F, Kieso R, Hite P. Automated impedance-based energy adjustment for defibrillation: experimental studies. Circulation 1985; 71:136-40. [PMID: 3964715 DOI: 10.1161/01.cir.71.1.136] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In defibrillation, current flow depends on the energy selected and the transthoracic impedance. If transthoracic impedance is high, current flow may be inadequate to defibrillate. We developed a method by which high transthoracic impedance is automatically compensated for by an increase in operator-selected energy when impedance is high. Transthoracic impedance was predicted in advance of the first shock by passing a low-level current between the defibrillator electrodes during the defibrillator charge cycle; a microprocessor monitored current flow and determined impedance. In 28 mongrel dogs we manipulated transthoracic impedance by placing glycerin-soaked gauze pads between the paddle electrodes and the chest. If the predicted impedance exceeded a preset value, the delivered energy was automatically increased by 40% or 100%. Using this impedance-based energy adjustment technique, we found significant improvements in current flow and success rate of shocks when energy was automatically increased to compensate for high transthoracic impedance. The use of transthoracic impedance as a basis for energy adjustment appears a promising technique to minimize the hazards of high electrical energy; it allows low-energy shocks in most patients while avoiding inappropriate low energies in patients with high impedance. Clinical trials are justified.
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32
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Sugrue DD, Holmes DR, Gersh BJ, Edwards WD, McLaran CJ, Wood DL, Osborn MJ, Hammill SC. Cardiac histologic findings in patients with life-threatening ventricular arrhythmias of unknown origin. J Am Coll Cardiol 1984; 4:952-7. [PMID: 6491087 DOI: 10.1016/s0735-1097(84)80056-x] [Citation(s) in RCA: 122] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Percutaneous endomyocardial biopsy (right ventricle in 10, left ventricle in 2) was performed in 12 patients, aged 9 to 57 years, with serious ventricular arrhythmias occurring in the setting of normal cardiac anatomy and mechanical function. Light microscopic examination of tissue revealed histologic abnormalities in 11 patients, including myocardial cellular hypertrophy in 7, interstitial fibrosis in 5, endocardial fibrosis in 2, myocardial degenerative changes in 1 and increased interstitial cellularity in 1. One patient had histologic evidence of acute lymphocytic myocarditis. Thus, a majority of patients with serious ventricular arrhythmias and normal cardiac anatomy had histologic abnormalities, bringing into question the concept of primary electrical heart disease or idiopathic ventricular tachycardia.
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33
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Lake CL, Sellers TD, Nolan SP, Crosby IK, Wellons HA, Crampton RS. Determinants of reperfusion cardiac electrical activity after cold cardioplegic arrest during coronary bypass surgery. Am J Cardiol 1984; 54:519-25. [PMID: 6332515 DOI: 10.1016/0002-9149(84)90241-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
In a prospective study of 99 patients with coronary artery disease, reperfusion of the heart after a period of ischemia (protected by contemporary techniques of myocardial preservation) resulted in spontaneous resumption of cardiac electrical activity in 53%, spontaneous defibrillation in 10%, reperfusion ventricular fibrillation (VF) in 32% and indeterminate rhythm in 5%. In hearts spontaneously developing rhythms excluding VF (as opposed to hearts requiring direct-current shock), factors significantly associated were a higher plasma potassium concentration (5.2 vs 4.8 mEq/liter), shorter reperfusion time (1 vs 4 minutes), higher plasma magnesium concentration (1.36 vs 1.25 mg/dl) and a lower myocardial temperature (27 vs 32 degrees C). The duration of ischemia, arterial blood gas levels, plasma catecholamine levels, plasma ionized calcium levels, volume of cardioplegia and mean arterial pressure did not relate to occurrence of spontaneous episodes. However, VF developed in 39 of 52 patients (75%) with spontaneous resumption of electrical activity. This event was associated with lower myocardial temperature. Thus, direct-current shocks were ultimately required in 77 of the 99 patients (78%). Although certain thermal, biochemical and hemodynamic variables facilitate spontaneous resumption of cardiac rhythm, the development of VF may negate the potential benefit of this event in the prevention of myocardial damage from direct-current defibrillation.
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34
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Abstract
Recent technological advances have enhanced our ability to diagnose and treat ventricular fibrillation (VF). Self-adhesive electrode pads for external defibrillation are as effective as standard hand-held paddle electrodes, and have substantial advantages for monitoring during transportation and in the emergency department/intensive care unit/critical care unit. These electrode pads work equally well whether placed in apex-anterior or apex-posterior positions. Preapplication in calm, prearrest circumstances assures accurate placement and enhances shock success. Transthoracic impedance is a critical determinant of the success of low-energy shocks. Prediction of transthoracic impedance in advance of the first shock is now feasible. First-shock energy can then be based on impedance, and inappropriate low energies for high-impedance patients may be avoided. Automatic external defibrillation by minimally trained rescuers extends our ability to treat out-of-hospital ventricular fibrillation. A vertical defibrillation pathway, using the tongue as one electrode site, allows rapid, automated detection of VF. Animal defibrillation studies and preliminary human studies (during elective cardioversion) have demonstrated the efficacy of the pathway and defined the impedance and energy requirements. Clinical trials of the device for out-of-hospital defibrillation are now in progress.
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35
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Kerber RE, Kouba C, Martins J, Kelly K, Low R, Hoyt R, Ferguson D, Bailey L, Bennett P, Charbonnier F. Advance prediction of transthoracic impedance in human defibrillation and cardioversion: importance of impedance in determining the success of low-energy shocks. Circulation 1984; 70:303-8. [PMID: 6733884 DOI: 10.1161/01.cir.70.2.303] [Citation(s) in RCA: 100] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The purposes of this study were to evaluate a method that predicts transthoracic impedance in advance of defibrillating shocks in humans and to assess the importance of transthoracic impedance in low-energy defibrillation. Via defibrillator electrodes we applied 31 kHz current to the chest during the defibrillator charge cycle, before the defibrillating shock was actually delivered. The current flow was limited by transthoracic impedance; a microprocessor monitored the predischarge current flow and determined the predischarge impedance by calibration against known resistance values. Actual impedance to the defibrillating shock was also determined and compared with the predicted impedance. With this approach we predicted impedance in 19 patients who received 66 shocks for ventricular and atrial arrhythmias. Predicted impedance (y) correlated very well with actual impedance (x):y = .90x + 11.3; r = .97. To determine the importance of impedance in defibrillation and cardioversion, we prospectively gathered data from 96 patients who received shocks of various energies for ventricular or atrial arrhythmias. In patients with high transthoracic impedance (greater than 97 omega), low-energy shocks (less than or equal to 100 J) for ventricular defibrillation had only a 20% success rate as opposed to a 70% success rate for low-energy shocks in patients with low or average impedance (p less than .05). We conclude that transthoracic impedance can be accurately predicted in advance of defibrillation and cardioversion. This method permits the preshock identification of patients with high impedance in whom attempts to defibrillate with low-energy shocks are inappropriate.
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Kerber RE, Martins JB, Kelly KJ, Ferguson DW, Kouba C, Jensen SR, Newman B, Parke JD, Kieso R, Melton J. Self-adhesive preapplied electrode pads for defibrillation and cardioversion. J Am Coll Cardiol 1984; 3:815-20. [PMID: 6693652 DOI: 10.1016/s0735-1097(84)80258-2] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The efficacy of self-adhesive electrode pads for defibrillation and cardioversion was assessed in 80 patients who received 267 shocks from self-adhesive pads. In all but two patients, defibrillation or cardioversion was achieved at least once. The pads were equally effective when used in the apex-anterior or apex-posterior position. The transthoracic impedance using self-adhesive pads was 75 +/- 21 ohms (mean +/- standard deviation), which is similar to previously reported transthoracic impedance in defibrillation, using standard hand-held electrode paddles of 67 +/- 36 ohms. It is concluded that self-adhesive electrode pads are effective for defibrillation and cardioversion.
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37
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Shiner SL, Gold MI. The epidemiology of defibrillation in a medical school complex. Resuscitation 1984; 11:91-102. [PMID: 6322270 DOI: 10.1016/0300-9572(84)90037-6] [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: 01/19/2023]
Abstract
Defibrillation is the definitive treatment for ventricular fibrillation (VF). Participation of physicians, paramedical personnel and lay people in cardiopulmonary resuscitation has significantly increased the survival from ventricular fibrillation. The number of defibrillators has increased and their primary placement within the hospital and community has changed. We studied the location, age, history, characteristics and maintenance of every defibrillator (n = 190) within a three hospital, medical school complex. Most defibrillators had been acquired recently but some dated from 1967. More than 85% were plug-in, non-portable. The government hospital had the lowest ratio of defibrillators to beds, but its maintenance, reliability and records were ths most efficient. We conclude that the increase in the number of defibrillators and its modernization reflects their importance, and that the type of hospital determines the age, type of machine, maintenance, and quantity.
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38
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Ventriglia WJ, Hamilton GC. Electrical Interventions in Cardiopulmonary Resuscitation: Defibrillation. Emerg Med Clin North Am 1983. [DOI: 10.1016/s0733-8627(20)30808-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Kerber RE, Hoyt R, Aronson A, Kieso R, Melton J. Evaluation of a new defibrillation pathway--the tongue-epigastric route. I. Experimental studies in dogs. J Am Coll Cardiol 1983; 2:966-72. [PMID: 6630773 DOI: 10.1016/s0735-1097(83)80247-2] [Citation(s) in RCA: 13] [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: 01/21/2023]
Abstract
The purpose of this study was to determine the efficacy of a tongue-epigastric defibrillation route in anesthetized dogs. Ventricular fibrillation was induced by rectangular pulses passed down a transvenous catheter into the right ventricle. Three groups of dogs were studied. Group I (15 dogs) received shocks from a 12 cm2 tongue electrode, a 50 cm2 circular, gelled self-adhesive electrode pad placed on the epigastrium and standard transthoracic defibrillator paddle electrodes. Shocks were given at energy levels of 50 to 460 joules (delivered energy, 50 ohm resistance). The success of the tongue-epigastric shocks in achieving defibrillation, and the resistance and current flow were determined at each energy level and compared with the same energy shocks from the standard transthoracic electrodes. In Group II (five dogs), comparisons were made between the 12 cm2 tongue electrode used in the first group of dogs and a larger tongue electrode of 40 cm2. In Group III (five dogs), intracardiac current flow (potential gradient) with tongue-epigastric and standard transthoracic electrodes was studied. In Group I, defibrillation success with the tongue-epigastric electrodes ranged from no success at 50 to 100 joules to 83% success at 460 joules. With standard transthoracic electrodes, success rates ranged from 65% at 50 joules to 100% at 300 joules. At all energies tested, the resistance was significantly higher and current significantly lower using tongue-epigastric compared with transthoracic electrodes. The higher tongue-epigastric resistance is probably related to the longer interelectrode distance; the correlation between interelectrode distance (x, in centimeters) and resistance (y, in ohms) in these dogs was y = 2.2x + 29.6, r = 0.78.(ABSTRACT TRUNCATED AT 250 WORDS)
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40
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Kerber RE, Jensen SR, Gascho JA, Grayzel J, Hoyt R, Kennedy J. Determinants of defibrillation: prospective analysis of 183 patients. Am J Cardiol 1983; 52:739-45. [PMID: 6624665 DOI: 10.1016/0002-9149(83)90408-3] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Previous studies have suggested that a number of factors may influence the ability to defibrillate: the transthoracic resistance and resultant current flow, the paddle electrode size, the duration of preshock ventricular fibrillation (VF) and cardiopulmonary resuscitation, metabolic abnormalities, body weight, the shock energy selected, and whether the patient is receiving lidocaine. To examine the effect of these variables, a prospective study was conducted of 183 patients who received direct-current shocks for VF. Overall defibrillation rates approached 90%, even in patients with secondary VF, but rates of successful resuscitation and survival were much lower. Patients who never defibrillated despite multiple shocks had a prolonged duration of cardiopulmonary resuscitation preceding the first shock (21 +/- 14 minutes) and systemic hypoxia and acidosis. These conditions tended to occur in patients who initially had cardiac arrest from causes other than VF: asystole, severe bradycardia and electromechanical dissociation. In such patients, VF developed only as a late event, which was then often unresponsive to attempted defibrillation. The other factors examined were not major determinants of defibrillation.
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Abstract
Remarkable advances have been made in the management of cardiac disease in the last 20 years, but antiarrhythmic drug strategy in the acute phase of myocardial infarction remains less than satisfactory. Primary ventricular fibrillation (VF), once considered predictable on the basis of detection of "warning arrhythmias," cannot be anticipated. Management must be either expectant or prophylactic. Restriction of drug use to selected patients and the apparent lack of effect of VF on late prognosis argue for the former approach, yet safe and effective prevention of VF is an attractive therapeutic goal. High-dose intravenous lidocaine probably offers efficacy but the risk-benefit ratio of this regimen is still debated. Adoption of a prophylactic regimen mandates drug administration to a large number of patients who either are not at risk of developing VF (noninfarct patients) or who are destined not to develop VF (70 to 95% of infarct patients). Ventricular arrhythmias other than VF are common in acute infarction and, for emotional rather than scientific reasons, often are aggressively treated. Little evidence exists to support this management. Few ventricular arrhythmias at this time in infarction have either immediate importance or prognostic significance. Reevaluation of antiarrhythmic drug use and arrhythmia treatment in acute myocardial infarction is long overdue. However, there is a paucity of controlled data upon which to base new strategies, and clinical research in this field is hampered by ethical considerations, by rigidly held but unscientifically based beliefs and by a lack of fundamental knowledge of arrhythmia mechanisms and their significance.
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Geuze RH, de Vente J. Arrhythmias and left ventricular function after defibrillation during acute myocardial infarction in the intact dog. Am Heart J 1983; 106:292-9. [PMID: 6869210 DOI: 10.1016/0002-8703(83)90195-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The purpose of this study was to assess the recovery of the left ventricular pressure (PLV), and the incidence and type of arrhythmias after effective low-dose defibrillation (Imax = 18-70 A) in healthy hearts and in hearts with acute myocardial infarction (AMI) in the intact dog. In fifteen dogs 84 episodes of fibrillation-defibrillation were studied in the healthy heart and 53 episodes were studied in the acute phase of myocardial infarction 1/2 to 3 hours after occlusion of a part of the left anterior descending artery by a catheter technique. Time to recovery of PLV depended on duration of fibrillation (tF) and cumulative defibrillation current (I 1/2), and became critical at tF greater than 45 seconds and I 1/2 greater than 45 A. Total duration of arrhythmias due to defibrillation increased with increasing tF and I 1/2. Arrhythmias which have a relative greater chance of resulting in refibrillation or which may seriously decrease the cardiac output occurred more often with I 1/2 greater than 55 A (p less than 0.001), when 50% of episodes were followed by these arrhythmias. No differences were found in responses between the healthy heart and the heart with AMI.
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de Visme GH, Furness A. Electrical waveforms for cardiac defibrillation which dissipate least heat in the cardiac circuit. Med Biol Eng Comput 1983; 21:259-63. [PMID: 6876897 DOI: 10.1007/bf02478491] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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