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Xing C, Jin Q, Zhang N, Liu S, Lin C, Wu Q, Luo Q, Liu A, Wu L. Effect of flunarizine on defibrillation outcomes and early refibrillation in a canine model of prolonged ventricular fibrillation. Exp Physiol 2019; 104:1630-1637. [PMID: 31465138 PMCID: PMC6899960 DOI: 10.1113/ep087068] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 08/23/2019] [Indexed: 11/20/2022]
Abstract
New Findings What is the central question of this study? Can successful electrical shock in combination with a delayed after‐depolarization (DAD) blocker suppress early refibrillation episodes following long duration ventricular fibrillation (LDVF)? What is the main finding and its importance? Flunarizine significantly reduced the activation of LDVF and early ventricular fibrillation (VF) recurrence following LDVF, suggesting that DADs potentially contribute to refibrillation in prolonged VF. Thus, DAD inhibition can be used as an adjunctive therapy for electrical defibrillation to treat prolonged VF and suppress refibrillation following LDVF.
Abstract This study attempts to detect changes in the defibrillation threshold (DFT) at different stages of ventricular fibrillation (VF) (short duration VF, SDVF; long duration VF, LDVF) and during early refibrillation following successful defibrillation of LDVF by giving flunarizine, a blocker of delayed after‐depolarizations (DADs). Twelve beagles were divided into two groups (the control group, n = 6; and the flunarizine group, n = 6). Two 64‐electrode basket catheters were deployed into the left and the right ventricles for global endocardium mapping. The DFTs of SDVF and LDVF were determined at 20 s and 7 min, respectively, after VF induction in each group. Any refibrillation episodes were recorded within 15 min after the first successful defibrillation of LDVF. In the flunarizine group, the SDVF‐DFT values before and after the drug were not significantly different. The 7 min LDVF‐DFTs were markedly reduced by 26% (P < 0.05, the control group) and 38% (P < 0.01, the flunarizine group) compared to the 20 s SDVF‐DFTs within each group. The difference between SDVF‐DFT and LDVF‐DFT after flunarizine was larger than that in the control group (213 ± 65 vs. 120 ± 84 V, P < 0.05). The number of refibrillation episodes per animal (1.3 ± 1.0) following successful defibrillation of LDVF after flunarizine was 48% of that in controls (2.7 ± 2.0, P < 0.05). The effect of flunarizine on SDVF‐DFT and LDVF‐DFT indicates that the role of DADs in the defibrillation mechanism may differ as VF continues. Flunarizine significantly reduced early VF recurrence following LDVF, suggesting that DADs potentially contribute to refibrillation in a canine model of prolonged VF.
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Affiliation(s)
- Chaofan Xing
- Department of Cardiology, Shanghai Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qi Jin
- Department of Cardiology, Shanghai Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ning Zhang
- Department of Cardiology, Shanghai Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shaohua Liu
- Department of Cardiology, Shanghai Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Changjian Lin
- Department of Cardiology, Shanghai Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qiong Wu
- Department of Cardiology, Shanghai Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qingzhi Luo
- Department of Cardiology, Shanghai Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ao Liu
- Department of Cardiology, Shanghai Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Liqun Wu
- Department of Cardiology, Shanghai Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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Panitchob N, Li L, Huang J, Ranjan R, Ideker RE, Dosdall DJ. Endocardial Activation Drives Activation Patterns During Long-Duration Ventricular Fibrillation and Defibrillation. Circ Arrhythm Electrophysiol 2017; 10:CIRCEP.117.005562. [PMID: 29247031 DOI: 10.1161/circep.117.005562] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 10/26/2017] [Indexed: 11/16/2022]
Abstract
BACKGROUND Understanding the mechanisms that drive ventricular fibrillation is essential for developing improved defibrillation techniques to terminate ventricular fibrillation (VF). Distinct organization patterns of chaotic, regular, and synchronized activity were previously demonstrated in VF that persisted over 1 to 2 minutes (long-duration VF [LDVF]). We hypothesized that activity on the endocardium may be driving these activation patterns in LDVF and that unsuccessful defibrillation shocks may alter activation patterns. METHODS AND RESULTS The study was performed using a 64-electrode basket catheter on the left ventricle endocardium and 54 6-electrode plunge needles inserted into the left ventricles of 6 dogs. VF was induced electrically, and after short-duration VF (10 seconds) and LDVF (7 minutes), shocks of increasing strengths were delivered every 10 seconds until VF was terminated. Endocardial activation patterns were classified as chaotic (varying cycle lengths and nonsynchronous activations), regular (highly repeatable cycle lengths), and synchronized (activation that spreads rapidly over the endocardium with diastolic periods between activations). CONCLUSIONS The results showed that the chaotic pattern was predominant in early VF, but the regular pattern emerges as VF progressed. The synchronized pattern only emerged occasionally during late VF. Failed defibrillation shocks changed chaotic and regular activation patterns to synchronized patterns in LDVF but not in short-duration VF. The regular and synchronized patterns of activation were driven by rapid activations on the endocardial surface that blocked and broke up transmurally, leading to an endocardial to epicardial activation rate gradient as LDVF progressed.
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Affiliation(s)
- Nuttanont Panitchob
- From the Nora Eccles Harrison Cardiovascular Research and Training Institute (N.P., R.R., D.J.D.), Division of Cardiothoracic Surgery, Department of Surgery (D.J.D.), and Division of Cardiovascular Medicine, Department of Medicine (L.L., R.R., D.J.D.), University of Utah, Salt Lake City; and Division of Cardiovascular Disease, School of Medicine, University of Alabama at Birmingham (J.H., R.E.I.)
| | - Li Li
- From the Nora Eccles Harrison Cardiovascular Research and Training Institute (N.P., R.R., D.J.D.), Division of Cardiothoracic Surgery, Department of Surgery (D.J.D.), and Division of Cardiovascular Medicine, Department of Medicine (L.L., R.R., D.J.D.), University of Utah, Salt Lake City; and Division of Cardiovascular Disease, School of Medicine, University of Alabama at Birmingham (J.H., R.E.I.)
| | - Jian Huang
- From the Nora Eccles Harrison Cardiovascular Research and Training Institute (N.P., R.R., D.J.D.), Division of Cardiothoracic Surgery, Department of Surgery (D.J.D.), and Division of Cardiovascular Medicine, Department of Medicine (L.L., R.R., D.J.D.), University of Utah, Salt Lake City; and Division of Cardiovascular Disease, School of Medicine, University of Alabama at Birmingham (J.H., R.E.I.)
| | - Ravi Ranjan
- From the Nora Eccles Harrison Cardiovascular Research and Training Institute (N.P., R.R., D.J.D.), Division of Cardiothoracic Surgery, Department of Surgery (D.J.D.), and Division of Cardiovascular Medicine, Department of Medicine (L.L., R.R., D.J.D.), University of Utah, Salt Lake City; and Division of Cardiovascular Disease, School of Medicine, University of Alabama at Birmingham (J.H., R.E.I.)
| | - Raymond E Ideker
- From the Nora Eccles Harrison Cardiovascular Research and Training Institute (N.P., R.R., D.J.D.), Division of Cardiothoracic Surgery, Department of Surgery (D.J.D.), and Division of Cardiovascular Medicine, Department of Medicine (L.L., R.R., D.J.D.), University of Utah, Salt Lake City; and Division of Cardiovascular Disease, School of Medicine, University of Alabama at Birmingham (J.H., R.E.I.)
| | - Derek J Dosdall
- From the Nora Eccles Harrison Cardiovascular Research and Training Institute (N.P., R.R., D.J.D.), Division of Cardiothoracic Surgery, Department of Surgery (D.J.D.), and Division of Cardiovascular Medicine, Department of Medicine (L.L., R.R., D.J.D.), University of Utah, Salt Lake City; and Division of Cardiovascular Disease, School of Medicine, University of Alabama at Birmingham (J.H., R.E.I.).
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Uzelac I, Herndon C, Farmer J, Fenton F. Electrocardiogram reconstruction from high resolution voltage optical mapping. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2016; 2016:3941-3944. [PMID: 28269147 DOI: 10.1109/embc.2016.7591589] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Electrocardiogram recordings during opucal mapping experiments in heart tissue are commonly used tu monitor the health of the preparation and to obtain dominant frequencies during arrhythmic and defibrillatory studies. However the use of ECG reconstructed from optical mapping is seldom used and to date it has not been strictly validated. In this manuscript we present the first detailed validation and comparison of Optical Mapping ECG, or OM-ECG, with standard ECG recordings by calculating the electrostatic potential in space as a function of the voltage measured optically and describe the different approximations that can be used to obtain unipolar or bipolar ECG recordings. We found that in small/medium hearts, such as rabbits, leads that are aligned apex to base only require activation recording from one surface (anterior or posterior) for the OM-ECG to match the ECG while leads aligned left to right may require both an anterior and posterior optical mapping recording. The discrepancy between leads is due to symmetries in the ventricular activations. In the case of ischemic hearts where activations even-out more, the match between the OM-ECG and standard ECG may require only one surface recording for both left-right and base-apex leads. We believe that this methodology has two main and direct applications in the study of cardiac dynamics. The first is during studies of defibrillation where information after the shock may be crucial in the development of new strategies, OM-ECGs do not suffer the current artifacts of standard ECGs during shocks and can be calculated during the entire activation. We present examples in rabbit ventricles where even low amplitude pacing artifacts are captured by the ECG but do not appear in the OM-ECG. The second use of this technique is for reconstructions of intramural dynamics in larger hearts where differences between the ECG and OM-ECG obtained from anterior and posterior recordings can be used to derive the intramural activation.
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Conover Z, Kern KB, Silver AE, Bobrow BJ, Spaite DW, Indik JH. Resumption of Chest Compressions After Successful Defibrillation and Risk for Recurrence of Ventricular Fibrillation in Out-of-Hospital Cardiac Arrest. Circ Arrhythm Electrophysiol 2014; 7:633-9. [DOI: 10.1161/circep.114.001506] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Background—
Prior investigation of out-of-hospital cardiac arrest has raised the concern that ventricular fibrillation (VF) recurrence may be triggered by chest compression (CC) resumption. We investigated predictors of VF recurrence after defibrillation, including timing of CC resumption.
Methods and Results—
Patients with witnessed out-of-hospital cardiac arrest and initial rhythm of VF from an Utstein-style database were analyzed. For each shock that defibrillated VF, CC resumption and VF recurrence times were determined. Shocks were classified according to postshock rhythm. Factors (age, sex, time from dispatch to monitor/defibrillator application, and CC resumption) that could predict VF recurrence were analyzed. CC resumption was categorized into groups: CC1, 1 to 5 seconds; CC2, 6 to 10 seconds; CC3, 11 to 30 seconds; and CC4, >30 seconds. Eighty-eight subjects were analyzed, with a total of 285 shocks, with 226 shocks that achieved asystole (n=102), organized rhythm (n=120), or monomorphic ventricular tachycardia (n=4). After a successful shock, CC resumption occurred at a median (interquartile range) of 8 (5–18) seconds. VF recurred after 166 shocks (74%) and recurred within 30 seconds in 69 shocks. There was no significant relationship between VF recurrence and factors analyzed including CC resumption time, nor stratified by postshock rhythm. The hazard ratios (HRs) for VF recurrence within 30 seconds for later CC groups (CC2, CC3, and CC4) relative to early CC resumption (CC1) were as follows: HR(CC2)=1.05 (
P
=0.9); HR(CC3)=1.75 (
P
=0.1); and HR(CC4)=0.67 (
P
=0.4).
Conclusions—
VF recurrence within 30 seconds of a defibrillatory shock was not dependent on timing of CC resumption in patients with witnessed arrest and initial rhythm of VF.
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Affiliation(s)
- Zacherie Conover
- From the Sarver Heart Center (Z.C., K.B.K., D.W.S., J.H.I.), and Arizona Emergency Medicine Research Center, Department of Emergency Medicine (D.W.S.), University of Arizona College of Medicine, Tucson; Maricopa Medical Center Department of Emergency Medicine, University of Arizona College of Medicine, Phoenix (B.J.B.); and ZOLL Medical Corporation, Chelmsford, MA (A.E.S.)
| | - Karl B. Kern
- From the Sarver Heart Center (Z.C., K.B.K., D.W.S., J.H.I.), and Arizona Emergency Medicine Research Center, Department of Emergency Medicine (D.W.S.), University of Arizona College of Medicine, Tucson; Maricopa Medical Center Department of Emergency Medicine, University of Arizona College of Medicine, Phoenix (B.J.B.); and ZOLL Medical Corporation, Chelmsford, MA (A.E.S.)
| | - Annemarie E. Silver
- From the Sarver Heart Center (Z.C., K.B.K., D.W.S., J.H.I.), and Arizona Emergency Medicine Research Center, Department of Emergency Medicine (D.W.S.), University of Arizona College of Medicine, Tucson; Maricopa Medical Center Department of Emergency Medicine, University of Arizona College of Medicine, Phoenix (B.J.B.); and ZOLL Medical Corporation, Chelmsford, MA (A.E.S.)
| | - Bentley J. Bobrow
- From the Sarver Heart Center (Z.C., K.B.K., D.W.S., J.H.I.), and Arizona Emergency Medicine Research Center, Department of Emergency Medicine (D.W.S.), University of Arizona College of Medicine, Tucson; Maricopa Medical Center Department of Emergency Medicine, University of Arizona College of Medicine, Phoenix (B.J.B.); and ZOLL Medical Corporation, Chelmsford, MA (A.E.S.)
| | - Daniel W. Spaite
- From the Sarver Heart Center (Z.C., K.B.K., D.W.S., J.H.I.), and Arizona Emergency Medicine Research Center, Department of Emergency Medicine (D.W.S.), University of Arizona College of Medicine, Tucson; Maricopa Medical Center Department of Emergency Medicine, University of Arizona College of Medicine, Phoenix (B.J.B.); and ZOLL Medical Corporation, Chelmsford, MA (A.E.S.)
| | - Julia H. Indik
- From the Sarver Heart Center (Z.C., K.B.K., D.W.S., J.H.I.), and Arizona Emergency Medicine Research Center, Department of Emergency Medicine (D.W.S.), University of Arizona College of Medicine, Tucson; Maricopa Medical Center Department of Emergency Medicine, University of Arizona College of Medicine, Phoenix (B.J.B.); and ZOLL Medical Corporation, Chelmsford, MA (A.E.S.)
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Defibrillation threshold varies during different stages of ventricular fibrillation in canine hearts. Heart Lung Circ 2012; 22:133-40. [PMID: 23021977 DOI: 10.1016/j.hlc.2012.08.059] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 08/09/2012] [Accepted: 08/29/2012] [Indexed: 11/23/2022]
Abstract
BACKGROUND Recent studies have shown that short duration ventricular fibrillation (SDVF) and long duration ventricular fibrillation (LDVF) are maintained by different mechanisms. The objective of this study is to evaluate how the defibrillation threshold (DFT) varies over the duration of fibrillation since the mechanism of VF maintenance changes as VF progresses. METHODS Twelve canines were randomly divided into two groups (Group A and B, n=6 each). DFTs were measured three times in each group: SDVF (20s), LDVF (3min in Group A and 7min in Group B) and the first episode of refibrillation after successful defibrillation for LDVF. Two 64-electrode baskets used to globally map the endocardium were deployed into the left ventricle and right ventricle, respectively. RESULTS LDVF-DFT in Group A was significantly higher than that of Group B (628±98V vs 313±81V, P<0.001). In Group B, the DFT of refibrillation was significantly increased compared with the LDVF-DFT (570±199V vs 313±81V, P=0.035) but did not differ from the DFT of refibrillation in Group A (570±199V vs 638±116V, P=0.39). Highly synchronised activation patterns on the left ventricular endocardium were observed between 3 and 7min of LDVF in Group B but not within 3min-LDVF in Group A or during refibrillation in each group. CONCLUSIONS DFT varied during different stages of VF. The highly synchronised activation patterns exhibiting after 3min VF might contribute to the decreased LDVF-DFT.
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High-energy defibrillation increases the dispersion of regional ventricular repolarization. J Interv Card Electrophysiol 2011; 32:81-6. [PMID: 21671072 DOI: 10.1007/s10840-011-9589-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Accepted: 05/12/2011] [Indexed: 10/18/2022]
Abstract
PURPOSE This study evaluated the effects of shock energy on the dispersion of regional ventricular repolarization (DRVR), post-shock rhythm and sinus recovery time (SRT), and the relationship between DRVR and post-shock ventricular arrhythmias. MATERIALS AND METHODS Ten open-chest dogs were anesthetized. Ventricular fibrillation (VF) was electrically induced and recorded from a 6 × 6 unipolar electrode plaque (4 mm spacing) sutured on the left ventricular epicardium. Defibrillation threshold (DFT) was determined after 20 s of VF. DRVR was measured before VF, during the earliest post-shock sinus rhythm, and during sinus rhythm 30 s following shocks. Post-shock rhythm and SRT were evaluated after energies of 100% DFT, 125% DFT, 175% DFT, and 250% DFT. RESULTS In the100% DFT group, the DRVR of the earliest sinus rhythm and 30 s after successful defibrillation was not significantly different than that before VF. But the DRVRs were significantly increased in 125% DFT, 175% DFT, and 250% DFT group. DRVR after defibrillation in the 250% DFT group was higher than those in the 100% DFT and 125% DFT groups. SRT in the 250% DFT group was significantly longer than that in the other groups .The incidence of post-shock ventricular tachycardia was increased when a high-shock energy was applied (P = 0.041). CONCLUSION DRVR was increased by application of high-energy defibrillation associated with SRT prolongation. The increased DRVR may play an important role in the onset of post-shock ventricular tachycardia.
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Purkinje activation precedes myocardial activation following defibrillation after long-duration ventricular fibrillation. Heart Rhythm 2009; 7:405-12. [PMID: 20061187 DOI: 10.1016/j.hrthm.2009.11.025] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2009] [Accepted: 11/25/2009] [Indexed: 11/20/2022]
Abstract
BACKGROUND While reentry within the ventricular myocardium (VM) is responsible for the maintenance of short-duration ventricular fibrillation (SDVF; VF duration <1 minute), Purkinje fibers (PFs) are important in the maintenance of long-duration ventricular fibrillation (LDVF; VF duration >1 minute). OBJECTIVE The purpose of this study was to test the hypothesis that the mechanisms of defibrillation may also be different for SDVF and LDVF. METHODS A multielectrode basket catheter was deployed in the left ventricle of eight beagles. External defibrillation shocks were delivered with a ramp-up protocol after SDVF (20 seconds) and LDVF (150 seconds). Earliest VM and PF activations were identified after the highest energy shock that failed to terminate VF and the successful shock. RESULTS Defibrillation was successful after 36 +/- 12 and 181 +/- 14 seconds for SDVF and LDVF, respectively. The time after shock delivery until earliest activation was detected for failed shocks and was significantly longer after LDVF (138.7 +/- 24.1 ms) than after SDVF (75.6 +/- 8.7 ms). Earliest postshock activation after SDVF typically initiated in the VM (14 of 16 episodes), while it always initiated in the PF (16 of 16 episodes) after LDVF. Sites of earliest activity during sinus rhythm correlated with sites of earliest postshock activation for PF-led cycles but not for VM-led cycles. CONCLUSION Earliest recorded postshock activation is in the Purkinje system after LDVF but not after SDVF. This difference raises the possibility that the optimal defibrillation strategy is different for SDVF and LDVF.
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Hsieh YC, Lin SF, Lin TC, Ting CT, Wu TJ. Therapeutic hypothermia (30 degrees C) enhances arrhythmogenic substrates, including spatially discordant alternans, and facilitates pacing-induced ventricular fibrillation in isolated rabbit hearts. Circ J 2009; 73:2214-22. [PMID: 19789414 DOI: 10.1253/circj.cj-09-0432] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Therapeutic hypothermia (TH, 30 degrees C) protects the brain from hypoxic injury. However, TH may potentiate the occurrence of lethal ventricular fibrillation (VF), although the mechanism remains unclear. The present study explored the hypothesis that TH enhances wavebreaks during VF and S(1) pacing, facilitates pacing-induced spatially discordant alternans (SDA), and increases the vulnerability of pacing-induced VF. METHODS AND RESULTS Using an optical mapping system, epicardial activations of VF were studied in 7 Langendorff-perfused isolated rabbit hearts at baseline (37 degrees C), TH (30 degrees C), and rewarming (37 degrees C). Action potential duration (APD)/conduction velocity (CV) restitution and APD alternans (n=6 hearts) were determined by S(1) pacing at these 3 stages. During TH, there was a higher percentage of VF duration containing epicardial repetitive activities (spatiotemporal periodicity) (P<0.001). However, TH increased phase singularity number (wavebreaks) during VF (P<0.05) and S(1) pacing (P<0.05). TH resulted in earlier onset of APD alternans (P<0.001), which was predominantly SDA (P<0.05), and increased pacing-induced VF episodes (P<0.05). TH also decreased CV, shortened wavelength, and enhanced APD dispersion and the spatial heterogeneity of CV restitution. CONCLUSIONS TH (30 degrees C) increased the vulnerability of pacing-induced VF by (1)facilitating wavebreaks during VF and S(1) pacing, and (2)enhancing proarrhythmic electrophysiological parameters, including promoting earlier onset of APD alternans (predominantly SDA) during S(1) pacing.
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Affiliation(s)
- Yu-Cheng Hsieh
- Cardiovascular Center, Taichung Veterans General Hospital, Taichung and Department of Internal Medicine, Institute of Clinical Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan
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Wu TJ, Lin SF, Hsieh YC, Chiu YT, Ting CT. Repetitive endocardial focal discharges during ventricular fibrillation with prolonged global ischemia in isolated rabbit hearts. Circ J 2009; 73:1803-11. [PMID: 19652397 DOI: 10.1253/circj.cj-09-0260] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Ventricular fibrillation (VF) during prolonged (>5 min) global ischemia (GI) could be due to repetitive endocardial focal discharges (REFDs). This hypothesis was tested in isolated rabbit hearts. METHODS AND RESULTS With optical mapping, simultaneous endocardial (left ventricle, LV) and epicardial (both ventricles) activations during VF with prolonged GI were studied (protocol I, 8 hearts). Lugol solution was applied to the LV endocardium in additional 5 hearts after 5-min GI (protocol II). During prolonged GI, sustained VF (>30 s) was successfully induced in 7 protocol I hearts. The dominant frequency of summed optical signals at the LV endocardium was higher than at the epicardium (P<0.05). Mapping data showed that after 5-min GI, REFDs were present in >90% for recording time. There were 18 windows of optical recording showing spontaneous VF termination. In 10, once REFDs ceased, the VF episode terminated immediately. Electrical defibrillation was also performed on 3 hearts. Eight shocks showed early VF recurrence after successful defibrillation. REFDs were consistently involved in the initiation period of recurrence. In protocol II, Lugol subendocardial ablation diminished REFD genesis during re-induced VF. These VF episodes were all non-sustained. CONCLUSIONS REFDs at the LV endocardium were important for both VF maintenance and post-shock recurrence during prolonged GI in this model.
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Affiliation(s)
- Tsu-Juey Wu
- Cardiovascular Center, Taichung Veterans General Hospital, Taichung, Taiwan.
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Hsieh YC, Horng TL, Lin SF, Lin TC, Ting CT, Wu TJ. d,l-Sotalol at therapeutic concentrations facilitates the occurrence of long-lasting non-stationary reentry during ventricular fibrillation in isolated rabbit hearts. Circ J 2009; 73:39-47. [PMID: 19008631 PMCID: PMC3060151 DOI: 10.1253/circj.cj-08-0540] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2024]
Abstract
BACKGROUND The effects of d,l-sotalol at therapeutic concentrations ( METHODS AND RESULTS By using an optical mapping system, epicardial activation patterns of VF were studied in 6 Langendorff-perfused rabbit hearts at baseline, during 10 mg/L d,l-sotalol infusion, and after washout. In an additional 4 hearts, action potential duration (APD), conduction velocity, and wavelength (WL) restitutions were determined. During d,l-sotalol infusion, VF was terminated in 3 of the 6 hearts. Only 1 heart developed transient ventricular tachycardia (VT). d,l-Sotalol reduced the number of phase singularities (ie, wavebreak) during VF (P<0.05), and it also increased the occurrence frequency (P<0.05) and lifespan (P<0.05) of epicardial reentry during VF. These reentries were non-stationary in nature and did not anchor on anatomical structures. Restitution data showed that d,l-sotalol flattened APD restitution. Furthermore, APD dispersion and spatial heterogeneity of restitutions were not enhanced by d,l-sotalol. CONCLUSIONS d,l-Sotalol at therapeutic concentrations decreased wavebreak and facilitated the occurrence of long-lasting, non-stationary reentry during VF. However, VT rarely occurred. The related mechanisms include: (1) flattening of APD restitution without enhancement of spatial heterogeneity of electrophysiological properties, causing wavefront organization, and (2) WL prolongation, preventing steady anchoring of reentry.
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Affiliation(s)
- Yu-Cheng Hsieh
- Cardiovascular Center, Taichung Veterans General Hospital and Department of Internal Medicine, Faculty of Medicine, Institute of Clinical Medicine, Cardiovascular Research Center, National Yang-Ming University School of Medicine, Taipei, Taiwan
| | - Tzyy-Leng Horng
- Department of Applied Mathematics, Feng-Chia University, Taichung, Taiwan
| | - Shien-Fong Lin
- Krannert Institute of Cardiology and the Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN
| | - Tung-Chao Lin
- Cardiovascular Center, Taichung Veterans General Hospital and Department of Internal Medicine, Faculty of Medicine, Institute of Clinical Medicine, Cardiovascular Research Center, National Yang-Ming University School of Medicine, Taipei, Taiwan
| | - Chih-Tai Ting
- Cardiovascular Center, Taichung Veterans General Hospital and Department of Internal Medicine, Faculty of Medicine, Institute of Clinical Medicine, Cardiovascular Research Center, National Yang-Ming University School of Medicine, Taipei, Taiwan
| | - Tsu-Juey Wu
- Cardiovascular Center, Taichung Veterans General Hospital and Department of Internal Medicine, Faculty of Medicine, Institute of Clinical Medicine, Cardiovascular Research Center, National Yang-Ming University School of Medicine, Taipei, Taiwan
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Allred JD, Killingsworth CR, Allison JS, Dosdall DJ, Melnick SB, Smith WM, Ideker RE, Walcott GP. Transmural recording of shock potential gradient fields, early postshock activations, and refibrillation episodes associated with external defibrillation of long-duration ventricular fibrillation in swine. Heart Rhythm 2008; 5:1599-606. [PMID: 18984539 DOI: 10.1016/j.hrthm.2008.08.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2008] [Accepted: 08/16/2008] [Indexed: 11/19/2022]
Abstract
BACKGROUND Knowledge of the shock potential gradient (nablaV) and postshock activation is limited to internal defibrillation of short-duration ventricular fibrillation (SDVF). OBJECTIVE The purpose of this study was to determine these variables after external defibrillation of long-duration VF (LDVF). METHODS In six pigs, 115-20 plunge needles with three to six electrodes each were inserted to record throughout both ventricles. After the chest was closed, the biphasic defibrillation threshold (DFT) was determined after 20 seconds of SDVF with external defibrillation pads. After 7 minutes of LDVF, defibrillation shocks that were less than or equal to the SDVF DFT strength were given. RESULTS For DFT shocks (1632 +/- 429 V), the maximum minus minimum ventricular voltage (160 +/- 100 V) was 9.8% of the shock voltage. Maximum cardiac nablaV (28.7 +/- 17 V/cm) was 4.7 +/- 2.0 times the minimum nablaV (6.2 +/- 3.5 V/cm). Although LDVF did not increase the DFT in five of the six pigs, it significantly lengthened the time to earliest postshock activation following defibrillation (1.6 +/- 2.2 seconds for SDVF and 4.9 +/- 4.3 seconds for LDVF). After LDVF, 1.3 +/- 0.8 episodes of spontaneous refibrillation occurred per animal, but there was no refibrillation after SDVF. CONCLUSION Compared with previous studies of internal defibrillation, during external defibrillation much less of the shock voltage appears across the heart and the shock field is much more even; however, the minimum nablaV is similar. Compared with external defibrillation of SDVF, the biphasic external DFT for LDVF is not increased; however, time to earliest postshock activation triples. Refibrillation is common after LDVF but not after SDVF in these normal hearts, indicating that LDVF by itself can cause refibrillation without requiring preexisting heart disease.
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Affiliation(s)
- James D Allred
- Department of Medicine, Division of Cardiovascular Disease, University of Alabama at Birmingham, Birmingham, Alabama, USA
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