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Wolf J, Buckley GJ, Rozanski EA, Fletcher DJ, Boller M, Burkitt-Creedon JM, Weigand KA, Crews M, Fausak ED. 2024 RECOVER Guidelines: Advanced Life Support. Evidence and knowledge gap analysis with treatment recommendations for small animal CPR. J Vet Emerg Crit Care (San Antonio) 2024; 34 Suppl 1:44-75. [PMID: 38924633 DOI: 10.1111/vec.13389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Accepted: 04/25/2024] [Indexed: 06/28/2024]
Abstract
OBJECTIVE To systematically review the evidence and devise clinical recommendations on advanced life support (ALS) in dogs and cats and to identify critical knowledge gaps. DESIGN Standardized, systematic evaluation of literature pertinent to ALS following Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology. Prioritized questions were each reviewed by Evidence Evaluators, and findings were reconciled by ALS Domain Chairs and Reassessment Campaign on Veterinary Resuscitation (RECOVER) Co-Chairs to arrive at treatment recommendations commensurate to quality of evidence, risk:benefit relationship, and clinical feasibility. This process was implemented using an Evidence Profile Worksheet for each question that included an introduction, consensus on science, treatment recommendations, justification for these recommendations, and important knowledge gaps. A draft of these worksheets was distributed to veterinary professionals for comment for 4 weeks prior to finalization. SETTING Transdisciplinary, international collaboration in university, specialty, and emergency practice. RESULTS Seventeen questions pertaining to vascular access, vasopressors in shockable and nonshockable rhythms, anticholinergics, defibrillation, antiarrhythmics, and adjunct drug therapy as well as open-chest CPR were reviewed. Of the 33 treatment recommendations formulated, 6 recommendations addressed the management of patients with nonshockable arrest rhythms, 10 addressed shockable rhythms, and 6 provided guidance on open-chest CPR. We recommend against high-dose epinephrine even after prolonged CPR and suggest that atropine, when indicated, is used only once. In animals with a shockable rhythm in which initial defibrillation was unsuccessful, we recommend doubling the defibrillator dose once and suggest vasopressin (or epinephrine if vasopressin is not available), esmolol, lidocaine in dogs, and/or amiodarone in cats. CONCLUSIONS These updated RECOVER ALS guidelines clarify the approach to refractory shockable rhythms and prolonged CPR. Very low quality of evidence due to absence of clinical data in dogs and cats continues to compromise the certainty with which recommendations can be made.
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Affiliation(s)
- Jacob Wolf
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida, USA
| | | | - Elizabeth A Rozanski
- Department of Clinical Sciences, Tufts University School of Veterinary Medicine, North Grafton, Massachusetts, USA
| | - Daniel J Fletcher
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - Manuel Boller
- VCA Canada Central Victoria Veterinary Hospital, Victoria, British Columbia, Canada
- Faculty of Veterinary Medicine, Department of Veterinary Clinical and Diagnostic Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Jamie M Burkitt-Creedon
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, California, USA
| | - Kelly A Weigand
- Cary Veterinary Medical Library, Auburn University, Auburn, Alabama, USA
- Flower-Sprecher Veterinary Library, Cornell University, Ithaca, New York, USA
| | - Molly Crews
- Department of Small Animal Clinical Sciences, Texas A&M University College of Veterinary Medicine & Biomedical Sciences, College Station, Texas, USA
| | - Erik D Fausak
- University Library, University of California, Davis, Davis, California, USA
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Schauvliege S, van Loon G, De Clercq D, Devisscher L, Deprez P, Gasthuys F. Cardiovascular responses to transvenous electrical cardioversion of atrial fibrillation in anaesthetized horses. Vet Anaesth Analg 2009; 36:341-51. [PMID: 19538571 DOI: 10.1111/j.1467-2995.2009.00470.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To examine the influence of direct current shock application in anaesthetized horses with atrial fibrillation (AF) and to study the effects of cardioversion to sinus rhythm (SR). STUDY DESIGN Prospective clinical study. ANIMALS Eight horses successfully treated for AF (transvenous electrical cardioversion after amiodarone pre-treatment). METHODS Cardioversion catheters and a pacing catheter were placed under sedation [detomidine 10 microg kg(-1) intravenously (IV)]. After additional sedation (5-10 microg kg(-1) detomidine, 0.1 mg kg(-1) methadone IV), anaesthesia was induced with ketamine, 2.2 mg kg(-1) and midazolam, 0.06 mg kg(-1) (IV) in a sling and maintained with isoflurane in oxygen. Flunixin meglumine, 1.1 mg kg(-1), was administered IV. Shocks were delivered as biphasic truncated exponential waves, synchronized with the R-wave of the electrocardiogram. Monitoring included pulse oximetry, electrocardiography, capnography, inhalational anaesthetic agent concentration, arterial blood pressure, LiDCO and PulseCO cardiac index (CI) and arterial blood gases. Values before and after the first unsuccessful shock and before and after cardioversion to SR were compared. RESULTS Values before the first shock were comparable to reported values in healthy, isoflurane anaesthetized horses. Reliable CI measurements could not be obtained using the PulseCO technique. Intermittent positive pressure ventilation was required in most horses (bradypnea and/or PaCO(2) >8 kPa, 60 mmHg), while dobutamine was administered in two horses (0.3-0.5 microg kg(-1) minute(-1)). After the 1st unsuccessful shock application, systolic arterial pressure (SAP) was decreased (p = 0.025), other recorded values were not influenced (CI measurements not available for this analysis). SR was associated with increases in CI (p = 0.039) and stroke index (p = 0.002) and a decrease in SAP (p = 0.030). CONCLUSIONS AND CLINICAL RELEVANCE Despite the presence of AF, cardiovascular function was well maintained during anaesthesia and was not affected by shock application. Cardiac index and stroke index increased and SAP decreased after cardioversion.
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Affiliation(s)
- Stijn Schauvliege
- Faculty of Veterinary Medicine, Department of Surgery and Anaesthesia of Domestic Animals, Ghent University, Salisburylaan, Merelbeke, Belgium.
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Bellei MHM, Kerr C, McGurrin MKJ, Kenney DG, Physick-Sheard P. Management and complications of anesthesia for transvenous electrical cardioversion of atrial fibrillation in horses: 62 cases (2002-2006). J Am Vet Med Assoc 2007; 231:1225-30. [PMID: 17937553 DOI: 10.2460/javma.231.8.1225] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To describe management of anesthesia for transvenous electrical cardioversion (TVEC) in horses and report perianesthetic complications. DESIGN Retrospective case series. ANIMALS 62 horses with atrial fibrillation and without underlying cardiac disease and 60 horses without atrial fibrillation. PROCEDURES Medical records of horses with atrial fibrillation anesthetized for TVEC were reviewed, as were records of horses without atrial fibrillation anesthetized for magnetic resonance imaging (MRI). The TVEC group horses were compared with MRI group horses for incidence of intraoperative bradycardia and use of inotropic drugs. Data obtained included patient signalment, weight, duration of anesthesia, heart rate and arterial blood pressure during anesthesia, anesthetic drugs administered, mode of ventilation, perioperative complications, and quality of recovery. RESULTS The TVEC group horses were > 1 year of age and were predominantly Standardbreds. The TVEC group horses underwent a total of 76 anesthetic episodes. For 40 (52.6%) anesthetic episodes, horses received xylazine only for premedication, and for 26 (34.2%) anesthetic episodes, horses received xylazine and butorphanol. Induction of anesthesia consisted of ketamine administration in various combinations with diazepam and guaifenesin for 74 (97.4%) anesthetic episodes and ketamine alone for 2 (2.6%). Bradycardia in horses was encountered during 15 of 76 (19.7%) anesthetic episodes. Minor signs of possible postanesthetic myopathy occurred following 6 (7.9%) anesthetic episodes. No significant difference was found between TVEC and MRI group horses regarding incidence of bradycardia and inotropic drug administration. CONCLUSIONS AND CLINICAL RELEVANCE Short-duration anesthesia for TVEC of atrial fibrillation in horses without underlying cardiac disease was a safe procedure.
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Affiliation(s)
- Maria Helena M Bellei
- Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada
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Kamochi H, Yamanouchi Y, Saku K. Effects of Angiotensin Converting Enzyme Inhibitor and Angiotensin II Receptor Blocker on Ventricular Defibrillation Threshold. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2006; 29:747-52. [PMID: 16884511 DOI: 10.1111/j.1540-8159.2006.00429.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Angiotensin converting enzyme (ACE) inhibitors and Angiotensin II (AII) receptor blockers have previously been shown to be beneficial in treating patients with not only hypertension but also with cardiovascular diseases. Therefore, such drugs may potentially be used in patients with an implantable cardioverter defibrillator (ICD) who show cardiac dysfunctions. OBJECTIVE This study aimed to determine effects of short-term administration of the ACE inhibitor (CV-3317) and the AII receptor blocker (CV-11974, an active form of candesartan) on internal defibrillation threshold (DFT) in anesthetized canine hearts. METHODS DFTs were evaluated using a "hot can" defibrillation lead system in: (a) seven dogs following three intravenous administrations of 20 cc saline; (b) 11 dogs that received intravenous CV-3317 doses of 1 mg/kg, 10 mg/kg, and 50 mg/kg; and in (c) 10 dogs that were intravenously given 0.1 mg/kg, 1 mg/kg, and 10 mg/kg CV-11974. DFTs were determined using a "down-up down-up" protocol. RESULTS Mean DFT delivered energies at baseline and following three consecutive intravenous saline injections were 16.4 +/- 9.3 J, 15.3 +/- 7.5 J, 15.9 +/- 7.1 J, and 15.5 +/- 5.6 J, respectively. Those at baseline and following 1 mg/kg, 10 mg/kg, and 50 mg/kg intravenous CV-3317 were 12.9 +/- 6.4 J, 12.2 +/- 6.4 J, 11.0 +/- 6.6 J, and 11.9 +/- 6.6 J, respectively. Similarly, those at baseline and after 0.1 mg/kg, 1 mg/kg, and 10 mg/kg CV-11974 were 13 +/- 6.6 J, 12.5 +/- 6 J, 12.9 +/- 5.8 J, and 13.2 +/- 6.6 J, respectively. There were no significant differences between DFT at baseline and the others in each treatment group. CONCLUSIONS Since an ACE inhibitor and an AII receptor blocker did not alter DFT, such drugs may be useful in ICD patients without a decrease in safety margins.
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Affiliation(s)
- Hideyuki Kamochi
- Department of Cardiology, Chikushi Hospital, Fukuoka University, Fukuoka, Japan
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Ayoub IM, Kolarova J, Kantola RL, Sanders R, Gazmuri RJ. Cariporide minimizes adverse myocardial effects of epinephrine during resuscitation from ventricular fibrillation. Crit Care Med 2005; 33:2599-605. [PMID: 16276186 DOI: 10.1097/01.ccm.0000186773.88576.83] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Epinephrine given during closed-chest resuscitation increases blood flow across the coronary and cerebral circuits. However, epinephrine worsens reperfusion arrhythmias and intensifies postresuscitation myocardial dysfunction. We investigated whether cariporide-a selective sodium-hydrogen exchanger isoform-1 inhibitor-could ameliorate such adverse effects without diminishing its vasopressor actions. DESIGN Randomized animal study. SETTING University-based animal laboratory. SUBJECTS Twenty-four anesthetized male domestic pigs (29-43 kg). INTERVENTIONS Ventricular fibrillation was electrically induced and left untreated for 8 mins. Pigs were randomized to receive after 2 mins of chest compression a 3 mg/kg bolus of cariporide (n = 8), a 0.02 mg/kg bolus of epinephrine (n = 8), or a combination of cariporide and epinephrine (n = 8). Additional doses of epinephrine were given if the coronary perfusion pressure decreased below 15 mm Hg. Successfully resuscitated pigs were observed for 72 hrs. MEASUREMENTS AND MAIN RESULTS The averaged coronary perfusion pressure was higher in the epinephrine (34 +/- 11 mm Hg, p = .001) and cariporide/epinephrine (35 +/- 10 mm Hg, p < .001) groups compared with the cariporide group (15 +/- 6 mm Hg). All pigs in the epinephrine and cariporide/epinephrine groups but only six in the cariporide group were successfully resuscitated and survived 72 hrs. During the immediate postresuscitation period, four of eight pigs in the epinephrine group had episodes of recurrent ventricular fibrillation or pulseless ventricular tachycardia requiring additional electrical shocks (7.0 +/- 6.4) but none in the cariporide and cariporide/epinephrine groups (chi-square, p = .008). Myocardial dysfunction occurred early after return of spontaneous circulation but only in the epinephrine group. CONCLUSIONS The combined administration of cariporide and epinephrine prompted adequate pressor effects during chest compression and facilitated reestablishment of cardiac activity without episodes of recurrent ventricular fibrillation or transient myocardial dysfunction as with epinephrine alone.
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Affiliation(s)
- Iyad M Ayoub
- Department of Medicine, Rosalind Franklin University of Medicine and Science, USA
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Yao T, Ashihara T, Ito M, Nakazawa K, Horie M. Refractory Gradient is Responsible for the Increase in Ventricular Vulnerability Under Sodium Channel Blockade. Circ J 2005; 69:345-53. [PMID: 15731543 DOI: 10.1253/circj.69.345] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Previous studies have shown that sodium channel (I(Na)) blockade increases ventricular vulnerability; however, there were differences in the degree of the increase. Because the vulnerable window (VW) is altered by the type of preshock refractory gradient (RG), the hypothesis was that the differences in the arrhythmogenesis of I(Na) blockade result from the different types of preshock RG employed. METHODS AND RESULTS Simulations of regio(Na)l electric shock following constant pacing stimuli in 2-dimensional bidomain myocardial sheets under I(Na) blockade were conducted using 3 types of preshock RG: longitudinally tilted (LRG), transversely tilted (TRG), and non-tilted RG (NRG). The increase in the degree of I(Na) blockade almost linearly decreased the conduction velocity. The action potential duration in the LRG and TRG cases was non-linearly shortened with the increase in INa blockade because of electrotonic influences, whereas in the case of NRG it was slightly prolonged. In both LRG and TRG cases, the VW for reentry induction by electric shock was considerably widened by the INa blockade; however, this was not the case for NRG in which the VW was rather narrowed by the INa blockade. CONCLUSION The type of preshock RG alters the degree of the increase in ventricular vulnerability under INa blockade.
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Affiliation(s)
- Takenori Yao
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Osu, Japan.
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Lischke V, Kessler P, Byhahn C, Westphal K, Amann A. [Transthoracic defibrillation. Physiologic and pathophysiologic principles and their role in the outcome of resuscitation]. Anaesthesist 2004; 53:125-36. [PMID: 14991189 DOI: 10.1007/s00101-003-0635-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
As one major link in the chain of survival, early transthoracic (external) cardiac defibrillation is aimed at the termination of ventricular flutter and ventricular fibrillation. Most important to the success of defibrillation is the passage of a defined amount of current through a critical mass of heart muscle. Different transthoracic resistances reduce the effective density of the current within the heart. As for other therapeutic intervention procedures, recommendations for the optimal strength of current to be applied to the fibrillating heart need to be evaluated and defined for therapeutical defibrillation too. Unnecessarily high current density causes damage to the heart and should be prevented. By using biphasic waveforms in contrast to monophasic impulses, the amount of current can be reduced but the same or even higher efficacy is attained. Therefore possible myocardial damage might be clearly reduced. Even with individually altered thoracic impedance effective conversion of cardiac rhythm can be achieved by device-controlled compensation and biphasic waveforms. According to their different mechanisms or origin (electrically induced or spontaneously caused by organic heart disease) the probability of successful conversion of the cardiac rhythm by one single electrical impulse varies. The optimum point in time for defibrillation during resuscitation needs to be redefined. In order to improve comparability, further studies should use standardized definitions for successful defibrillation relating to the resulting cardiac rhythm.
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Affiliation(s)
- V Lischke
- Anästhesie-Abteilung und operative Intensivmedizin, Hochtaunus-Kliniken gGmbH, Bad Homburg.
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Abstract
INTRODUCTION Lidocaine is known to increase the defibrillation threshold (DFT) of monophasic shocks (MS) and have no effect on DFT of biphasic shocks (BS). The aim of this study was to enhance our understanding of the mechanisms of vulnerability and defibrillation through the investigation of this difference. METHODS AND RESULTS We studied the effect of 15 microM lidocaine on shock-induced vulnerability using fluorescent imaging of Langendorff-perfused rabbit hearts. Vulnerability was assessed as vulnerable window with shock strengths of 15 to 150 V and vulnerable period (VP) with shock delivery phase of 0% to 100% of action potential duration (% APD). With MS, lidocaine caused a significant increase in both the upper limit of vulnerability (ULV, 71 +/- 17 V vs 120 +/- 1.5 V, P < 0.01) and upper limit of VP (91 +/- 8.0% APD vs 110 +/- 4.2% APD, P < 0.01). With BS, lidocaine had no effect on ULV (40 +/- 3.4 V vs 45 +/- 4.5 V) and did not increase the upper limit of VP (78 +/- 8.9% APD vs 96 +/- 12% APD, P < 0.01). Lidocaine caused reduction of the conduction velocity during pacing (0.58 +/- 0.08 m/s vs 0.44 +/- 0.05 m/s, P < 0.01), shock-induced break excitation (0.82 +/- 0.17 m/s vs 0.30 +/- 0.07 m/s, P < 0.01), and postshock reentry (0.34 +/- 0.07 m/s vs 0.19 +/- 0.08 m/s, P < 0.01). Lidocaine had no effect on shock-induced virtual electrode polarization. CONCLUSION Lidocaine increased MS ULV due to slowing of shock-induced break-excitation wavefronts, which resulted in enhanced probability of survival of virtual electrode induced phase singularity. Lidocaine had no effect on BS ULV because no break excitation was induced by BS. Reduction of conduction velocity by lidocaine resulted in increased dispersion of repolarization and led to upper limit of VP increase for both MS and BS.
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Affiliation(s)
- Li Li
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106-7207, USA
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Sims JJ, Schoff KL, Loeb JM, Wiegert NA. Regional gap junction inhibition increases defibrillation thresholds. Am J Physiol Heart Circ Physiol 2003; 285:H10-6. [PMID: 12623782 DOI: 10.1152/ajpheart.01074.2002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It is clear that ischemia inhibits successful defibrillation by altering regional electro-physiology. However, the exact mechanisms are unclear. This study investigated whether regional gap junction inhibition increases biphasic shock defibrillation thresholds (DFT). Sixteen swine were instrumented with a mid-left anterior descending (LAD) perfusion catheter for regional infusion of 0.5 mM/h heptanol (n = 8) or saline (n = 8). DFT values and effective refractory periods (ERP) at five myocardial sites were determined. Regional conduction velocity (CV) was determined in an LAD drug-perfused and nondrug-perfused region in an additional seven swine. Regional heptanol infusion increased 50% DFT values by 33% (P = 0.01) and slowed CV by 42-59% (P < 0.01) but did not affect ERP. Regional heptanol also increased CV dispersion by approximately 270% (P < 0.05) but did not change ERP dispersion. Regional placebo did not alter any of these parameters. Furthermore, regional heptanol infusion induced spontaneous ventricular fibrillation in eight of eight animals. Increasing spatial conduction velocity dispersion by impairing regional gap junction conductance increased DFT values. Dispersion in conduction velocity slowing during regional ischemia may be an important determinant of defibrillation efficacy.
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Affiliation(s)
- J Jason Sims
- School of Pharmacy, University of Wisconsin, Madison, WI 53705, USA.
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Zhang Y, Karlsson G, Davies LR, Coddington WJ, Kerber RE. Biphasic and monophasic transthoracic defibrillation in pigs with acute left ventricular dysfunction. Resuscitation 2001; 50:95-101. [PMID: 11719135 DOI: 10.1016/s0300-9572(01)00329-x] [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: 10/18/2022]
Abstract
OBJECTIVE Our purpose was to compare biphasic versus monophasic shock success for VF termination in a porcine model of acute left ventricular (LV) dysfunction. BACKGROUND For the termination of ventricular fibrillation (VF), transthoracic biphasic waveform shocks achieve higher success rates than monophasic shocks. However, the effectiveness of biphasic versus monophasic defibrillation in a setting of left ventricular dysfunction has not been reported. METHODS In 23 open-chest adult swine (15-25 kg), LV dysfunction [> or =25% decline in cardiac output (CO)] was induced by continuous inhalation of halothane (1-1.75%). Each pig randomly received transthoracic biphasic and monophasic shocks at three energy levels (30, 50 and 100 J) in two conditions: baseline and LV dysfunction. Halothane effect on left ventricular size and contraction was measured by echocardiography in three additional swine. RESULTS With halothane, pigs demonstrated a decline in CO (baseline 4.16+/-0.19, halothane 2.72+/-0.19 l/min, P<0.01), mean arterial pressure (baseline 107.2+/-3.5, halothane 80.1+/-3.4 mmHg, P<0.01) and increased left ventricular end-diastolic pressure (baseline 6.4+/-0.9, halothane 12.7+/-0.8 mmHg, P<0.01). LV diameters increased and fractional shortening fell. During baseline, biphasic shocks achieved significantly greater success (termination of VF) compared to monophasic waveforms (100 J: biphasic 83.3+/-9.5 versus monophasic 38.9+/-9.5%, P<0.01; 50 J: biphasic 67.1+/-8.8 versus monophasic 11.8+/-5.7%, P<0.01; 30 J: biphasic: 31.9+/-6.4 versus monophasic 0+/-0%, P<0.01). The superiority of the biphasic waveform to terminate VF was retained during LV dysfunction at all energy levels (100 J: biphasic 78.3+/-7.3 versus monophasic 37.5+/-8.1%, P<0.01; 50 J: biphasic 65.5+/-11.5 versus monophasic 11.7+/-5.9%, P<0.01; 30 J: biphasic: 40.6+/-8.0 versus monophasic 3.1+/-3.1%, P<0.01). Within both waveforms, there were no significant differences in percent shock success at any energy level comparing baseline with LV dysfunction. CONCLUSION In this porcine model of acute LV dysfunction, biphasic waveform shocks were not only superior to monophasic waveform shocks for termination of VF during baseline, but retained superiority to monophasic waveform shocks when LV dysfunction was present.
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Affiliation(s)
- Y Zhang
- The Cardiovascular Center, College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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Ujhelyi MR, Sims JJ, Dubin SA, Vender J, Miller AW. Defibrillation energy requirements and electrical heterogeneity during total body hypothermia. Crit Care Med 2001; 29:1006-11. [PMID: 11378613 DOI: 10.1097/00003246-200105000-00025] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Determine the effects of hypothermia on defibrillation energy requirements and cardiac electrophysiology. DESIGN Prospective randomized acute intervention trial. SETTING Medical center animal laboratory. SUBJECTS Fifteen domestic farm swine. INTERVENTIONS Swine were randomized to a hypothermia group (n = 8) or a control group (n = 7). All animals were instrumented with a transvenous defibrillation system connected to a defibrillator that delivers a biphasic-truncated waveform. Values for defibrillation energy requirements were measured at baseline (normothermia, 38-40 degrees C) and during treatment with total body hypothermia (30 degrees C) or no temperature change (sham). Hypothermia was induced by circulating ice-water through anterior and posterior surgical thermal blankets. MEASUREMENTS AND MAIN RESULTS Defibrillation energy requirement values at 20%, 50%, and 80% were determined by using an up/down method. In the hypothermia group, defibrillation energy requirement values at baseline did not significantly change during hypothermia (defibrillation energy requirements 50% = 14 +/- 2 J vs. 15 +/- 2 J, respectively). Similarly, the defibrillation energy requirement values in the control group did not change from baseline to sham phase (defibrillation energy requirements 50% = 12 +/- 1 J vs. 13 +/- 1 J, respectively). Hypothermia profoundly affected cardiac electrophysiology, decreasing ventricular fibrillation threshold by 72%, conduction velocity by 25% (p < .01), and tissue excitability, while it prolonged ventricular repolarization and refractoriness by 7.5% to 15%, respectively (p < .05). CONCLUSIONS Total body cooling to 30 degrees C was highly arrhythmogenic, although this unstable electrophysiological state did not alter ventricular defibrillation energy requirements. These data suggest that hypothermia may be used to slow metabolic processes without concern over the ability to successfully defibrillate and treat hypothermia-induced arrhythmias.
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Affiliation(s)
- M R Ujhelyi
- University of Georgia College of Pharmacy, Augusta VA Medical Center, and Medical College of Georgia School of Medicine, Augusta, GA, USA
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Sims JJ, Miller AW, Ujhelyi MR. Regional hyperkalemia increases ventricular defibrillation energy requirements: role of electrical heterogeneity in defibrillation. J Cardiovasc Electrophysiol 2000; 11:634-41. [PMID: 10868736 DOI: 10.1111/j.1540-8167.2000.tb00025.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
INTRODUCTION Increased spatial electrical heterogeneity has been associated with impaired defibrillation efficacy. The current study investigated the relationship between electrical heterogeneity and defibrillation efficacy by manipulating spatial electrical heterogeneity. METHODS AND RESULTS We increased spatial electrical heterogeneity by infusing potassium chloride (2 to 4 mEq/hour) or placebo in the left anterior descending artery in 13 pentobarbital anesthetized swine. Electrophysiologic measurements at five myocardial sites and defibrillation energy requirement (DER) values were determined at baseline and during regional hyperkalemia (n = 7) or placebo (n = 6). Regional potassium infusion was titrated to a 20% reduction in action potential duration in the perfused region. Regional hyperkalemia increased biphasic DER values by 87% (P = 0.02), whereas infusion of placebo did not alter defibrillation efficacy. Regional hyperkalemia decreased myocardial repolarization and refractoriness in the perfused region by 21% (P < 0.001) and 18% (P = 0.01), respectively. However, regional hyperkalemia increased ventricular fibrillation cycle length (VFCL) by 39% (P = 0.008). Consequently, dispersions of repolarization, refractoriness, and VFCL were significantly increased by 169%, 92%, and 200%, respectively. Regional hyperkalemia also increased ventricular conduction time to the perfused region by 54% (P = 0.006), indicating conduction velocity dispersion, while not affecting local pacing threshold or local voltage gradient. CONCLUSION Regional hyperkalemia increased DER values. Regional hyperkalemia likely impairs defibrillation by increasing myocardial electrical heterogeneity, which supports the theory that electrical heterogeneity promotes nonuniform propagation of early postshock activations, thereby inhibiting defibrillation.
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Affiliation(s)
- J J Sims
- University of Georgia College of Pharmacy, Medical College of Georgia School of Medicine, and Augusta VA Medical Center, USA
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Scheatzle MD, Menegazzi JJ, Allen TL, Durham SB. Evaluation of biphasic transthoracic defibrillation in an animal model of prolonged ventricular fibrillation. Acad Emerg Med 1999; 6:880-6. [PMID: 10490248 DOI: 10.1111/j.1553-2712.1999.tb01234.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVES To determine whether a biphasic defibrillation waveform (BDW) would produce a superior rate of converting prolonged ventricular fibrillation (VF) into a perfusing rhythm and delay the occurrence of asystole and/or pulseless electrical activity (PEA) during the resuscitation attempt, when compared with a monophasic defibrillation waveform (MDW). METHODS The authors performed a prospective, randomized, blinded experiment using an established swine model of prolonged VF. Thirty-four mixed-breed domestic swine (mean mass 22.9 kg) were sedated (ketamine/xylazine), anesthetized (isoflurane), and intubated. Aortic and femoral venous catheters were placed. ECG was monitored continuously. The animals were shocked into VF (3-s, 100-mA, 60-Hz shock), and were untreated for 8 minutes. Advanced Cardiac Life Support (ACLS) began with 1 minute of standardized (Thumper) chest compressions and ventilation. The animals were randomized to treatment with either BDW or MDW. Standard ACLS protocols were followed. The energy sequence was 2.5 J/kg first, 3.5 J/kg second, and 4.5 J/kg for all subsequent shocks. Outcome variables were time to event of asystole/PEA, return of spontaneous circulation (ROSC), and one-hour survival. Data were analyzed with two-tailed Fisher's exact test and Kaplan-Meier survival plots (alpha = 0.05). RESULTS ROSC occurred more frequently in the BDW group (7/17) compared with the MDW group (1/17); p = 0.04. Survival analysis showed that the BDW significantly delayed the occurrence of asystole/PEA during the resuscitation attempt when compared with the MDW; log-ranked p = 0.02. One-hour survival rates (5/17 BDW and 1/17 MDW, p = 0.17) did not differ. CONCLUSIONS BDW resulted in a superior rate of ROSC and delay in the occurrence of asystole/ PEA during the resuscitation attempt when compared with MDW.
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Affiliation(s)
- M D Scheatzle
- Department of Emergency Medicine, Allegheny General Hospital, MCP-Hahnemann University, School of Medicine, Pittsburgh, PA 15212, USA.
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16
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Kühlkamp V, Mewis C, Suchalla R, Mermi J, Dörnberger V, Seipel L. Effect of amiodarone and sotalol on the defibrillation threshold in comparison to patients without antiarrhythmic drug treatment. Int J Cardiol 1999; 69:271-9. [PMID: 10402110 DOI: 10.1016/s0167-5273(99)00055-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
AIM OF THE STUDY It is generally accepted that chronic therapy with antiarrhythmic drugs might increase the defibrillation threshold at implantation of an implantable cardioverter defibrillator. A recently published animal study showed a minor effect of the class 1 antiarrhythmic drug lidocaine on the defibrillation threshold if biphasic shocks were used. METHODS AND RESULTS We therefore performed a retrospective analysis in 89 patients who received an ICD capable of monophasic (n=18) or biphasic (n=71) shocks with a transvenous lead system. In all patients the defibrillation threshold was determined according to the same step down protocol. In the 18 patients with a monophasic device the effects of chronic therapy with amiodarone (n=7) on the defibrillation threshold were evaluated in comparison to a group without antiarrhythmic treatment (n=11). In those patients receiving a biphasic device the effects of chronic therapy with amiodarone (n=29), sotalol (n=20) or no antiarrhythmic medication (n=22) on the defibrillation threshold were evaluated. The groups receiving a monophasic device did not differ in respect to age, sex, underlying cardiac disease, clinical arrhythmia (VT/VF), clinical functional status, left ventricular ejection fraction and the number of patients with additional subcutaneous electrodes. These parameters as well as the type of implanted device were not different between patient groups receiving a biphasic device. Patients on chronic amiodarone therapy receiving a monophasic device had a significantly higher defibrillation threshold (29.1 +/- 8.8 J) than patients without antiarrhythmic treatment (19.1 +/- 5.1 J, P = 0.021). The groups did not differ significantly in respect to the impedance measured at the shocking lead (P = 0.13). In three patients on chronic amiodarone an epicardiac lead system had to be implanted due to an inadequate monophasic defibrillation threshold compared to no patient without antiarrhythmic drug treatment (P = 0.043). In the patients with a biphasic device the intraoperative defibrillation threshold was not significantly different between the three study groups (P = 0.44). No patient received an epicardiac lead system. The defibrillation threshold in the amiodarone group was 15.3 +/- 7.3 J, in the sotalol group 14.4 +/- 7.2 J and in the patients without antiarrhythmic drug treatment 17 +/- 6.1 J. As well, no significant difference was seen between the groups in respect of the impedance of the high voltage electrode (P = 0.2). CONCLUSION With the use of a biphasic device in combination with a transvenous lead system the intraoperative defibrillation threshold is not significantly different between patients on chronic amiodarone in comparison to patients without antiarrhythmic drug treatment or patients on chronic oral sotalol. This is in contrast to our findings with a monophasic device.
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Affiliation(s)
- V Kühlkamp
- Medical Department III, University of Tübingen, Germany.
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17
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Murakawa Y, Yamashita T, Kanese Y, Omata M. Effect of a class III antiarrhythmic drug on the configuration of dose response curve for defibrillation. Pacing Clin Electrophysiol 1999; 22:479-86. [PMID: 10192857 DOI: 10.1111/j.1540-8159.1999.tb00476.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Antiarrhythmic agents with a Class III action are known to increase defibrillation efficacy. We investigated whether a Class III drug simply shifts the dose-response curve for defibrillation or more extensively alters the curve. Forty-five dogs were divided into four groups according to the shock waveform and the presence or absence of treatment with a novel Class III drug, MS-551 (2 mg/kg bolus + 0.02 mg/kg per min). In addition to the conventional transcardiac DFT, dose-response curves were obtained by fitting the results of 40 fibrillation-defibrillation sequences at five shock strengths to a logistic model. MS-551 significantly decreased DFT regardless of the shock waveform (control vs MS-551 = 306 +/- 79 V vs 229 +/- 72 V [monophasic shock, P < 0.05], or 227 +/- 42 V vs 176 +/- 26 V [biphasic shock, P < 0.005]). The dose-response curves in dogs treated with MS-551 had a gentler slope than those without treatment, and the ratio of the voltages corresponding to 50% and 90% defibrillation success (V90/V50) was significantly greater in the MS-551 group (monophasic: 1.21 +/- 0.06 vs. 1.62 +/- 0.42 [P < 0.005], biphasic: 1.20 +/- 0.05 vs 1.37 +/- 0.18 [P < 0.01]). The V90/DFT ratio was also significantly larger in the MS-551 group (monophasic: 1.22 +/- 0.12 vs 1.66 +/- 0.37 [P < 0.001]; biphasic: 1.19 +/- 0.11 vs 1.44 +/- 0.79 [P < 0.005]). Thus, this Class III drug decreased the shock strength corresponding to relatively higher success rate (approximately 90%) less markedly than that for moderate success rate (approximately 50%). These results suggest that a Class III drug does not simply shift the dose response curve in proportion to the change in DFT, but more extensively alters its configuration.
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Affiliation(s)
- Y Murakawa
- Second Department of Internal Medicine, University of Tokyo, Japan
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18
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Murakawa Y, Yamashita T, Kanese Y, Omata M. Do the effects of antiarrhythmic drugs on defibrillation efficacy vary among different shock waveforms? Pacing Clin Electrophysiol 1998; 21:1901-8. [PMID: 9793086 DOI: 10.1111/j.1540-8159.1998.tb00009.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This study was designed to extend our knowledge on how pharmacological modification of defibrillation efficacy is associated with shock waveform. In 35 anesthetized dogs, the baseline transcardiac DFT was determined using 12-ms monophasic and three biphasic waveforms (10 ms-2 ms, 8 ms-4 ms, and 6 ms-6 ms). Twenty-eight dogs were then treated with either lidocaine (n = 7), mexiletine (n = 7), dofetilide (n = 7), or MS-551 (n = 7), while 7 dogs were left untreated to confirm the reproducibility of DFT data. Subsequently, DFT measurements were repeated in all dogs. Waveform related differences of the baseline DFT were significant, and the monophasic DFT was higher than any of the biphasic DFTs. Lidocaine increased DFT by 11% +/- 12% (12-ms monophasic), 20% +/- 20% (10 ms-2 ms, P < 0.05), 13% +/- 20% (8 ms-4 ms), and 12% +/- 10% (6 ms-6 ms, P < 0.05). With infusion of mexiletine, the DFT increased by 17% +/- 16% (P < 0.05), 9% +/- 12%, 10% +/- 10% (P < 0.05), and 4% +/- 15%, respectively. Both dofetilide and MS-551 significantly decreased the DFT regardless of the pulse waveform (dofetilide: from -18% +/- 19% to -24% +/- 19%, MS-551; from -18% +/- 11% to -32% +/- 6%). In all drug groups, waveform related differences in DFT remained significant. These results support the view that the advantages of biphasic shock waveforms are not lessened by treatment with antiarrhythmic drugs.
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Affiliation(s)
- Y Murakawa
- Second Department of Internal Medicine, University of Tokyo, Japan
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19
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Murakawa Y, Yamashita T, Kanese Y, Omata M. Effect of atrial natriuretic peptide on electrical defibrillation efficacy. J Cardiovasc Electrophysiol 1998; 9:962-9. [PMID: 9786076 DOI: 10.1111/j.1540-8167.1998.tb00136.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: 11/30/2022]
Abstract
INTRODUCTION In vitro studies have suggested that human atrial natriuretic peptide (ANP) modulates the electrophysiologic properties of myocardial cells. This study assessed whether ANP could influence defibrillation efficacy. METHODS AND RESULTS In 35 anesthetized dogs, the transcardiac defibrillation threshold (DFT) as well as hemodynamic and electrophysiologic variables were determined before and during treatment with ANP (n = 11), hydralazine (n = 11), or saline (n = 13). ANP (1.5 microg/kg + 0.2 microg/kg per min) increased the plasma concentration of cyclic GMP (a second messenger for ANP) and significantly decreased aortic blood pressure (mean 100+/-11 mmHg to 83+/-15 mmHg). ANP also prolonged ventricular repolarization (effective refractory period 157+/-7 msec to 165+/-11 msec) and markedly reduced DFT (5.4+/-1.2 J to 3.8+/-0.7 J [P < 0.01]) without changing pulmonary artery pressure or sinus cycle length. Neither saline nor hydralazine (1.5 mg/kg) had a significant effect on DFT (saline 4.7+/-2.1 J to 4.6+/-2.4 J; hydralazine 4.3+/-2.0 J to 4.2+/-1.9 J), although hydralazine caused pronounced hypotension (mean aortic pressure 103+/-9 mmHg to 74+/-13 mmHg). CONCLUSION These results suggest that ANP increases defibrillation efficacy, and that this effect is not necessarily shared by other vasodilating agents.
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Affiliation(s)
- Y Murakawa
- Second Department of Internal Medicine, University of Tokyo, Japan.
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20
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Sims JJ, Miller AW, Ujhelyi MR. Disparate effects of biphasic and monophasic shocks on postshock refractory period dispersion. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:H1943-9. [PMID: 9841521 DOI: 10.1152/ajpheart.1998.274.6.h1943] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The magnitude by which a defibrillation shock extends the refractory period immediately postshock (refractory period extension, RPE) does not explain why biphasic shocks defibrillate with greater efficacy than monophasic shocks. It may be that spatial heterogeneity of RPE is a more important regulator of defibrillation efficacy. We measured RPE in 15 pentobarbital-anesthetized swine using 400-V biphasic and monophasic shocks of equal pulse duration at three discrete myocardial sites. Spatial heterogeneity of RPE was calculated as the difference between the maximum and minimum values of the three recording sites. Monophasic shocks produced greater magnitude of RPE than biphasic shocks at all sites tested (82 +/- 6 to 99 +/- 13 and 64 +/- 6 to 68 +/- 5 ms, respectively; P < 0.05). However, RPE dispersion was significantly less with biphasic shocks versus monophasic shocks (29 +/- 4 and 48 +/- 7 ms, respectively; P < 0.05). This suggests that one potential mechanism by which biphasic shocks defibrillate with greater efficacy is limiting postshock spatial heterogeneity of refractoriness. Thus these data support our hypothesis that RPE heterogeneity is a more likely predictor of defibrillation efficacy than magnitude of RPE.
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Affiliation(s)
- J J Sims
- University of Georgia College of Pharmacy, Medical College of Georgia, and Augusta Veterans Affairs Medical Center, Augusta, Georgia 30912, USA
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21
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Zhou L, Chen BP, Kluger J, Fan C, Chow MS. Effects of amiodarone and its active metabolite desethylamiodarone on the ventricular defibrillation threshold. J Am Coll Cardiol 1998; 31:1672-8. [PMID: 9626850 DOI: 10.1016/s0735-1097(98)00160-0] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVES We evaluated whether the reported difference in the ventricular defibrillation threshold (DFT) between short-term intravenous and oral amiodarone is due to the effect of amiodarone's active metabolite desethylamiodarone (DEA). BACKGROUND Amiodarone is frequently used in patients with implantable cardioverter-defibrillator devices (ICD). Long-term oral amiodarone raises the DFT, but intravenous amiodarone has not been shown to have this effect. DEA, an active metabolite of amiodarone, has different electrophysiologic properties than its parent compound and may be responsible for the observed different effects of intravenous and oral amiodarone on DFT. METHODS We ascertained the DFT in 24 pigs randomized to receive intravenous amiodarone, DEA or vehicle. Defibrillation was delivered through a transvenous lead system using a biphasic waveform. The DFT was determined using an up-down DFT algorithm and defined as the average minimal energies resulting in successful defibrillation delivered from ascending and descending serial shocks. RESULTS Amiodarone caused a dose-response increase in DFT (mean +/- SD) from 22.7 +/- 4.1 (baseline) to 26.1 +/- 2.9 (10 mg/kg body weight), p = 0.11, to 34.9 +/- 8.2 J (after an additional 15 mg/kg), p = 0.035. DEA (10 mg/kg) caused an increase in DFT from 20.5 +/- 6.3 to 33.9 +/- 13.6 J, p < 0.01. Addition of 15 mg/kg of DEA resulted in hemodynamic instability and thus DFT was not obtained. In the control group, DFT decreased from 26.8 +/- 7.7 at baseline to 23.1 +/- 7.4 (dose 1), p = 0.19, to 22.8 +/- 6.2 J (dose 2), p = 0.18. CONCLUSIONS DEA increases DFT by a greater amount than its parent drug amiodarone. There is an effect of intravenous amiodarone on DFT that is dose dependent.
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Affiliation(s)
- L Zhou
- Department of Pharmacy Services, Hartford Hospital, Connecticut 06102-5037, USA
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22
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LÉVY SAMUEL. The Role of Antiarrhythmic Drugs in Patients With Implanted Cardioverter Defibrillators. J Interv Cardiol 1998. [DOI: 10.1111/j.1540-8183.1998.tb00121.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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23
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McDaniel WC, Curtis JJ, Walls JT, Madsen RW. Effects of magnesium sulfate on electrical ventricular defibrillation of dogs. J Electrocardiol 1998; 31:137-43. [PMID: 9588660 DOI: 10.1016/s0022-0736(98)90045-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Magnesium ion infusion has been reported for treatment of hypomagnesemia often associated with myocardial infarction and with surgeries involving cardiopulmonary bypass (CPB). Magnesium infusion before CPB has been reported to adversely affect the ability to defibrillate after CPB. However, there are also reports of magnesium ion infusion facilitating defibrillation of refractory ventricular fibrillation. This study evaluated the isolated effect of magnesium ion infusion on the shock intensity requirements for electrical defibrillation. The electric current required to defibrillate with 50% success (the ED50) was estimated in five mongrel dogs at baseline and again after each of four magnesium sulfate (80 mg/kg) infusions. The total serum magnesium level increased from 2.32 +/- 0.08 mg/dL (mean +/- SD) to 7.92 +/- 0.80 mg/dL. The mean estimated ED50 decreased from 12.8 +/- 2.9 A at baseline, to 11.1 +/- 0.8 A after the fourth infusion (P < .05), decreasing the delivered energy by 25%. Magnesium sulfate infusion was associated with a significant decrease in the electrical requirements for defibrillation. Key words: magnesium, electrical ventricular defibrillation.
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Affiliation(s)
- W C McDaniel
- Department of Cardiothoracic Surgery, University of Missouri, Columbia 65212, USA
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Ujhelyi MR, Sims JJ, Miller AW. High-dose lidocaine does not affect defibrillation efficacy: implications for defibrillation mechanisms. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:H1113-20. [PMID: 9575914 DOI: 10.1152/ajpheart.1998.274.4.h1113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
This study assessed the effect of low (10 mg.kg-1.h-1) and very high (18 mg.kg-1.h-1) doses of lidocaine on defibrillation energy requirements (DER) to relate changes in indexes of sodium-channel blockade with changes in DER values using a dose-response study design. In group 1 (control; n = 6 pigs), DER values were determined at baseline and during treatment with 5% dextrose in water (D5W) and with D5W added to D5W. In group 2 (n = 7), DER values were determined at baseline and during treatment with low-dose lidocaine followed by high-dose lidocaine. In group 3 (n = 3), DER values were determined at baseline and high-dose lidocaine. Group 3 controlled for the order of lidocaine treatment with the addition of high-dose lidocaine after baseline. DER values in group 1 did not change during D5W. In group 2, low-dose lidocaine increased DER values by 51% (P = 0.01), whereas high-dose lidocaine added to low-dose lidocaine reduced DER values back to within 6% of baseline values (P = 0.02, low dose vs. high dose). DER values during high-dose lidocaine in group 3 also remained near baseline values (16.2 +/- 2.7 to 12.9 +/- 2.7 J), demonstrating that treatment order had no impact on group 2. Progressive sodium-channel blockade was evident as incremental reduction in ventricular conduction velocity as the lidocaine dose increased. Lidocaine also significantly increased ventricular fibrillation cycle length as the lidocaine dose increased. However, the greatest increase in DER occurred when ventricular fibrillation cycle length was minimally affected, demonstrating a negative correlation (P = 0.04). In summary, lidocaine has an inverted U-shaped DER dose-response curve. At very high lidocaine doses, DER values are similar to baseline and tend to decrease rather than increase. Increased refractoriness during ventricular fibrillation may be the electrophysiological mechanism by which high-dose lidocaine limits the adverse effects that low-dose lidocaine has on DER values. However, there is a possibility that an unidentified action of lidocaine is responsible for these effects.
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Affiliation(s)
- M R Ujhelyi
- University of Georgia College of Pharmacy, Augusta, USA
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25
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Sato S, Imagawa N. Effects of lidocaine and mexiletine on defibrillation energy requirements in animals treated with flecainide. Resuscitation 1998; 36:175-80. [PMID: 9627068 DOI: 10.1016/s0300-9572(98)00024-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We previously reported that mexiletine alone did not increase the ventricular defibrillation threshold (DFT). However it has been stressed that the interaction of antiarrhythmic drugs may be one of the cause of sudden death in patients taking flecainide or encainide. In the present study, the effect of lidocaine and mexiletine combined with flecainide on DFT was investigated. Experiments were performed on 27 mongrel dogs. Flecainide 2 mg kg(-1) was administered i.v. as a loading dose and repeated for maintenance. Lidocaine (n = 10) or mexiletine (n = 10), was cumulatively administered 15 min later. Saline was administered in control group (n = 7). In these groups, fibrillation/defibrillation trials were repeated. The flecainide concentration ranged from 0.84 to 1.02 microg ml(-1). The lidocaine and mexiletine concentrations increased up to 12.54 and 7.47 microg ml(-1), respectively. DFT15, 15 min after the administration of flecainide, increased from 2.0 to 3.2 J in lidocaine group (mean +/- S.E.M.; P < 0.05), from 2.1 to 3.7 J in mexiletine group (mean +/- S.E.M.; P < 0.05). DFT increased with lidocaine concentrations of 3.42 microg ml(-1) or higher, and mexiletine of 3.60 microg ml(-1) or higher (P < 0.05). In conclusion, both lidocaine and mexiletine elevated the DFT in the dog treated with flecainide, especially with lidocaine in a therapeutic concentration.
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Affiliation(s)
- S Sato
- Department of Anesthesiology, Institute of Clinical Medicine, University of Tsukuba, Ibaraki, Japan
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Winecoff Miller AP, Sims JJ, McSwain R, Ujhelyi MR. Lidocaine's effect on defibrillation threshold are dependent on the defibrillation electrode system: epicardial versus endocardial. J Cardiovasc Electrophysiol 1998; 9:312-20. [PMID: 9554736 DOI: 10.1111/j.1540-8167.1998.tb00916.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
INTRODUCTION Epicardial and endocardial defibrillation electrode systems affect myocardial electrophysiology and sympathetic function differently. Thus, we postulate that antiarrhythmic drugs will interact with these electrode systems differently. METHODS AND RESULTS Defibrillation energy requirements (DER) at 20% (ED20), 50% (ED50), and 80% (ED80) success were measured at baseline and during lidocaine (10 mg/kg per hour) or D5W treatment for epicardial and endocardial electrodes. Pigs were randomized to treatment (lidocaine or D5W) and electrode system, which resulted in four experimental groups: (1) epicardial electrode + D5W; (2) epicardial electrode + lidocaine; (3) endocardial electrode + D5W; and (4) endocardial electrode + lidocaine. ED50 DER (mean +/- SEM) values at baseline for groups 1-4 were 10.6+/-1, 8.5+/-1, 12.6+/-1, and 12.3+/-1 J, respectively. DER values for groups 1 and 3 during D5W were similar to baseline. Conversely, lidocaine increased ED50 DER values from 8.5+/-1 to 13.5+/-2 J (P < 0.05) in group 2 animals (epicardial electrodes). When lidocaine was administered to group 4 animals (endocardial electrodes), however, ED50 DER values remained similar to baseline values (12.3+/-1 to 14.3+/-2 J, P = NS). Lidocaine increased ED50 DER values by 59% with the epicardial electrode system, which was significantly greater than the 16% increase with the endocardial electrode system (P < 0.05). Electrophysiologic response and electrode impedance were similar between electrode systems. CONCLUSION Lidocaine increases DER values to a greater extent when using epicardial versus endocardial electrode system. Thus, drug-device interactions are dependent on the electrode system. These data suggest that the electrophysiologic milieu created by endocardial defibrillation mitigates the effects that lidocaine has on DER values.
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Affiliation(s)
- A P Winecoff Miller
- The University of Georgia College of Pharmacy, Augusta VA Medical Center, USA
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27
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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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Winecoff AP, Sims JJ, Markel ML, Ujhelyi MR. Pinacidil's Effects on Defibrillation Outcomes: Role of Increased Potassium Conductance Via the K(ATP) Channel. J Cardiovasc Pharmacol Ther 1997; 2:171-180. [PMID: 10684456 DOI: 10.1177/107424849700200304] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND: It has been shown that the inhibition of potassium ion conductance decreases defibrillation threshold. We postulated that if potassium conductance is a primary mechanism affecting defibrillation threshold values, then increasing potassium ion conductance will increase defibrillation values. The primary objective of this study was to determine if the ATP-dependent potassium (K(ATP)) channel opener pinacidil would increase defibrillation threshold values. The second objective was to prove that the observed changes were due to potassium conductance by using the K(ATP) inhibitor, glyburide, to reverse the electrophysiologic actions of pinacidil. The third objective was to determine if the electrophysiology action sof pinacidil correlate with changes in defibrillation threshold value. METHODS AND RESULTS: Domestic farm swine (n = 14) were anesthetized and intubated. Subsequently, they were instrumented with monophasic action potential catheters and epicardial defibrillation patches. Defibrillation threshold values, action potential duration, effective refractory period, and ventricular fibrillation cycle length were determined at baseline and during treatment phase 1 and treatment phase 2. Pigs were randomized into 2 groups: group 1 (n = 6) received D(5)W in treatment phase one followed by D(5)W in treatment phase 2 and group 2 (n = 8) received pinacidil in treatment phase one followed by the addition of glyburide in treatment phase two. DFT(ED50) did not change at baseline, treatment phase one or treatment phase two for group 1 (10.5 +/- 2, 11.1 +/- 1.7, 10.5 +/- 1.0 J) or for group 2 (10.1 +/- 2.2, 11.4 +/- 4.2, 11.4 +/- 3.0 J). Electrophysiologic parameters )QRS, effective refractory period, action potential duration(90), and ventricular fibrillation cycle length) were not significantly changed from baseline in group 1. In contrast, effective refractory period, action potential duration(90), and ventricular fibrillation cycle length significantly decreased at all recorded sites after the administration of pinacidil in group 2 (range of 7-13%, 6-9%, and 12-17%, respectively). However, pinacidil did not change the basal level of dispersion in effective refractory period, action potential duration, and ventricular fibrillation cycle length during paced rhythm or ventricular fibrillation. Glyburide reversed pinacidil's electrophysiologic actions. CONCLUSIONS: Pinacidil does not alter defibrillation threshold, but it reduces effective refractory period, action potential duration, and ventricular fibrillation cycle length and does not increase electrical heterogeneity. Therefore, changes in potassium channel conductance as well as shortening repolarization are unlikely primary mechanisms for elevating defibrillation threshold.
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Affiliation(s)
- AP Winecoff
- University of Georgia College of Pharmacy, Augusta, Georgia, USA
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Brode SE, Schwartzman D, Callans DJ, Gottlieb CD, Marchlinski FE. ICD-antiarrhythmic drug and ICD-pacemaker interactions. J Cardiovasc Electrophysiol 1997; 8:830-42. [PMID: 9255691 DOI: 10.1111/j.1540-8167.1997.tb00842.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Antiarrhythmic drugs and separate bradycardia pacing systems are prescribed commonly in patients with implantable cardioverter defibrillators (ICDs). Adverse effects of antiarrhythmic drugs on ICD function and adverse interactions between ICDs and pacemakers have been documented. The effect of antiarrhythmic drugs on the defibrillation threshold (DFT) in patients has not been well assessed. Most studies have been performed in animal models in which cardiac function was normal and drug doses were supraphysiologic. In addition, most studies have utilized monophasic defibrillation shock waveforms and epicardial lead systems. Despite the lack of clinical data applicable to current defibrillation systems, it appears that chronic amiodarone administration causes a significant DFT increase. In addition, antiarrhythmic drugs can influence antitachycardia pacing and tachycardia sensing. Defibrillation shocks can cause transient failure of pacemaker sensing and pacing, and cause spurious pacemaker reprogramming. Pacemaker function can result in ICD oversensing, leading to inappropriate therapy, or cause ICD undersensing, potentially resulting in failure to deliver therapy during ventricular fibrillation. The susceptibility of an ICD to undersensing appears related to the amplitude of the pacing stimulus artifact recorded by the ICD rate-sensing circuit and to the characteristics of the fibrillation electrogram. Preliminary data suggest that undersensing of ventricular fibrillation by current ICDs is an unlikely event.
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Affiliation(s)
- S E Brode
- Clinical Electrophysiology Laboratory, Allegheny University School of the Health Sciences, Philadelphia, Pennsylvania, USA
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Ujhelyi MR, Schur M, Frede T, Bottorff MB, Gabel M, Markel ML. Hypertonic saline does not reverse the sodium channel blocking actions of lidocaine: evidence from electrophysiologic and defibrillation studies. J Cardiovasc Pharmacol 1997; 29:61-8. [PMID: 9007672 DOI: 10.1097/00005344-199701000-00010] [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: 02/03/2023]
Abstract
Studies have shown that increasing extracellular sodium concentration can partially reverse sodium channel blockade. However, there is conflicting in vitro evidence in this regard for lidocaine. The effects of lidocaine on cardiac electrophysiology and defibrillation were studied in a basal and hypernatremic state to determine reversibility of sodium channel blockade. Electrophysiologic studies measured right ventricular effective refractory period at 350 ms pacing cycle length and QRS interval, JT interval, and monophasic action potential duration during sinus rhythm and right ventricular pacing (350 ms cycle length) in 14 pentobarbital-anesthetized swine (25-30 kg). Defibrillation threshold (DFT) was measured by quantitating successful conversion of sustained ventricular fibrillation to normal sinus rhythm. Each pig was randomly assigned to a treatment group with three study phases; group 1 = baseline, lidocaine (20 mg/kg/h), and lidocaine plus placebo (D5W; n = 7); and group 2 = baseline, lidocaine, and lidocaine plus hypertonic saline (2-3 mM/kg/h; n = 7). In groups 1 and 2, lidocaine infused alone significantly (p < 0.01) increased DFT values from baseline (9.8 +/- 3.9 to 15.7 +/- 5.8 J and 8.9 +/- 2.9 to 14.7 +/- 5.4 J, respectively) and increased QRS duration from baseline during right ventricular pacing (89 +/- 6 to 109 +/- 10 ms; p < 0.01; and 87 +/- 6 to 103 +/- 12 ms; p < 0.01). Lidocaine alone reduced right ventricular action potential duration (APD) in groups 1 and 2 (214 +/- 18 to 206 +/- 20 ms; p < 0.10; and 228 +/- 8 to 212 +/- 8 ms; p < 0.05), respectively, and it reduced paced JT interval in both groups (194 +/- 20 to 184 +/- 18 ms; p < 0.10; and 200 +/- 12 to 183 +/- 16 ms; p < 0.05), respectively. When hypertonic saline was added to lidocaine, DFT and QRS duration values were unaffected (14.7 +/- 5.4 to 16.1 +/- 3.7 J and 103 +/- 12 to 100 +/- 11 ms, respectively). However, APD and JT intervals returned to basal values when hypertonic saline was added to lidocaine (212 +/- 8 to 225 +/- 13; p < 0.05; and 183 +/- 16 to 192 +/- 18; p < 0.05, respectively). When D5W was added in the control group, no changes occurred in DFT or electrophysiologic values. Lidocaine slowed ventricular conduction velocity and reduced APD. The administration of hypertonic saline to increase extracellular sodium concentrations failed to reverse the effect of lidocaine on conduction-velocity slowing or elevated DFT values. Hypertonic saline did reverse the effects of lidocaine on repolarization parameters. These data suggest that shortening of repolarization is not a mechanism by which lidocaine makes it more difficult to defibrillate the heart.
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Affiliation(s)
- M R Ujhelyi
- University of Georgia College of Pharmacy, Augusta, USA
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Ujhelyi MR, Winecoff AP, Schur M, Frede T, Bottorff MB, Gabel M, Markel ML. Influence of hypertonic saline solution infusion on defibrillation efficacy. Chest 1996; 110:784-90. [PMID: 8797427 DOI: 10.1378/chest.110.3.784] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Hypertonic saline solution may enhance cardiac conduction via the fast inward sodium channel and alter transmembrane Ca+2 conductance via the sodium-calcium exchanger. Evidence suggests that both Ca+2 conductance and myocardial conduction velocity may affect ventricular defibrillation. Since hypertonic saline solution solutions (ie, sodium bicarbonate) may be administered to patients who have conditions that often require ventricular defibrillation (ie, cardiac arrest or hypovolemic shock), we studied the effect of hypertonic saline solution on the defibrillation threshold (DFT) in 16 pentobarbital-anesthetized domestic farm swine (20 to 30 kg). Defibrillation was performed using two interfaced epicardial electrode patches. DFTs were determined at baseline and during treatment phase. Pigs were randomly assigned to treatment consisting of either hypertonic saline solution (6 mmol/kg load, 2.0 to 3.0 mmol/kg infusion) to maintain serum sodium concentrations 10 to 15 mmol/L above baseline or control (D5W given in equal volume). DFT values (joules) that predicted 50% success were modeled from a best-fit histogram. Hypertonic saline solution did not change DFT values from baseline values (10.2 +/- 4.3 vs 10.8 +/- 7.0, respectively). Likewise, placebo (D5W) did not change DFT values from baseline values (10.1 +/- 4.5 vs 11.3 +/- 4.3). During treatment phase, DFT values were 99 +/- 28% of baseline values in the hypertonic saline solution group and 116 +/- 23% of baseline values in the D5W groups (p = 0.21). The administration of hypertonic saline solution also did not affect ventricular conduction velocity, right ventricular action potential duration, or right ventricular effective refractory period. These data indicate that hypertonic saline solution does not appreciably affect defibrillation efficacy or electrical treatment of ventricular fibrillation.
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Ujhelyi MR, Schur M, Frede T, Bottorff MB, Gabel M, Markel ML. Mechanism of antiarrhythmic drug-induced changes in defibrillation threshold: role of potassium and sodium channel conductance. J Am Coll Cardiol 1996; 27:1534-42. [PMID: 8626970 DOI: 10.1016/0735-1097(96)00027-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
OBJECTIVES We sought to determine which ion current predominantly affects defibrillation outcomes by using specific pharmacologic probes (lidocaine [a sodium channel blocking agent] and cesium [an outward potassium channel blocking agent]) in 26 swine. BACKGROUND The effect of a drug on sodium or potassium channel conductance, or both, may affect defibrillation threshold values. However, it is unknown which ion channel predominates. METHODS Each pig was randomly assigned to one of four treatment groups with two treatment phases: group 1 = placebo (D5W) in treatment phase I followed by placebo plus cesium in treatment phase II (n = 6); group 2 = lidocaine followed by lidocaine plus placebo (n = 7); group 3 = lidocaine followed by lidocaine plus cesium (n = 7); group 4 = placebo followed by placebo plus placebo (n = 6). Defibrillation threshold values and electrocardiographic measurements were obtained at baseline and at treatment phases I and II. RESULTS Lidocaine increased defibrillation threshold values from baseline by 71% in group 2 (p = 0.02) and by 92% in group 3 (p < 0.01). There were no changes in defibrillation threshold values from baseline to D5W in groups 1 and 4. When D5W was added to lidocaine in group 2 and D5W in group 4, there were no significant changes in defibrillation threshold values. However, when cesium was added to lidocaine in group 3, the elevated defibrillation threshold values (mean +/- SD) returned to baseline values (from 15.7 +/- 3.46 to 7.55 +/- 3.19 J, p < 0.01). Cesium added to D5W in group 1 also significantly reduced defibrillation threshold values from 7.10 +/- 1.27 to 4.14 +/- 1.75 J (p < 0.01). The effect of cesium on defibrillation threshold values was similar between groups 1 and 3, regardless of lidocaine, such that these values were reduced by 40 +/- 14% and 51 +/- 18%, respectively (p = 0.28). CONCLUSIONS Cesium, through potassium blockade, reverses lidocaine-induced elevation in defibrillation threshold values. The magnitude of defibrillation threshold reduction when cesium was added to lidocaine was similar to the defibrillation threshold reduction when cesium was added to placebo. Thus, inhibiting outward potassium conductance and prolonging repolarization decreases defibrillation threshold values independent of sodium channel blockade.
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Affiliation(s)
- M R Ujhelyi
- University of Georgia College of Pharmacy and Medical College of Georgia School of Medicine, Augusta 30912-2390, USA
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