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Coronel R. Noninvasive Testing for Brugada Syndrome. JACC Clin Electrophysiol 2024; 10:1825-1827. [PMID: 39093276 DOI: 10.1016/j.jacep.2024.05.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2024] [Accepted: 05/21/2024] [Indexed: 08/04/2024]
Affiliation(s)
- Ruben Coronel
- Department of Experimental Cardiology, Amsterdam University Medical Centers, Amsterdam, the Netherlands.
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2
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Abstract
Sudden cardiac death (SCD) is the most common cause of death in childhood hypertrophic cardiomyopathy (HCM) and occurs more frequently than in adult patients. Risk stratification strategies have traditionally been extrapolated from adult practice, but newer evidence has highlighted important differences between childhood and adult cohorts, with the implication that pediatric-specific risk stratification strategies are required. Current guidelines use cumulative risk factor thresholds to recommend implantable cardioverter defibrillator (ICD) implantation but have been shown to have limited discriminatory ability. Newer pediatric models that allow clinicians to calculate individualized estimates of 5-year risk allowing, for the first time, personalization of ICD implantation decision-making have been developed. This article describes the pathophysiology, risk factors, and approach to risk stratification for SCD in childhood HCM and highlights unanswered questions.
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Affiliation(s)
- Gabrielle Norrish
- Centre for Inherited Cardiovascular Diseases, Great Ormond Street Hospital, London, UK; Institute of Cardiovascular Sciences University College London, UK
| | - Juan Pablo Kaski
- Centre for Inherited Cardiovascular Diseases, Great Ormond Street Hospital, London, UK; Institute of Cardiovascular Sciences University College London, UK.
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3
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Prevention of sudden cardiac death in childhood-onset hypertrophic cardiomyopathy. PROGRESS IN PEDIATRIC CARDIOLOGY 2021. [DOI: 10.1016/j.ppedcard.2021.101412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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4
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Leong KMW, Ng FS, Shun-Shin MJ, Koa-Wing M, Qureshi N, Whinnett ZI, Linton NF, Lefroy D, Francis DP, Harding SE, Davies DW, Peter NS, Lim PB, Behr E, Lambiase PD, Varnava A, Kanagaratnam P. Non-invasive detection of exercise-induced cardiac conduction abnormalities in sudden cardiac death survivors in the inherited cardiac conditions. Europace 2021; 23:305-312. [PMID: 33083839 DOI: 10.1093/europace/euaa248] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 08/18/2020] [Indexed: 11/12/2022] Open
Abstract
AIMS Rate adaptation of the action potential ensures spatial heterogeneities in conduction across the myocardium are minimized at different heart rates providing a protective mechanism against ventricular fibrillation (VF) and sudden cardiac death (SCD), which can be quantified by the ventricular conduction stability (V-CoS) test previously described. We tested the hypothesis that patients with a history of aborted SCD due to an underlying channelopathy or cardiomyopathy have a reduced capacity to maintain uniform activation following exercise. METHODS AND RESULTS Sixty individuals, with (n = 28) and without (n = 32) previous aborted-SCD event underwent electro-cardiographic imaging recordings following exercise treadmill test. These included 25 Brugada syndrome, 13 hypertrophic cardiomyopathy, 12 idiopathic VF, and 10 healthy controls. Data were inputted into the V-CoS programme to calculate a V-CoS score that indicate the percentage of ventricle that showed no significant change in ventricular activation, with a lower score indicating the development of greater conduction heterogeneity. The SCD group, compared to those without, had a lower median (interquartile range) V-CoS score at peak exertion [92.8% (89.8-96.3%) vs. 97.3% (94.9-99.1%); P < 0.01] and 2 min into recovery [95.2% (91.1-97.2%) vs. 98.9% (96.9-99.5%); P < 0.01]. No significant difference was observable later into recovery at 5 or 10 min. Using the lowest median V-CoS scores obtained during the entire recovery period post-exertion, SCD survivors had a significantly lower score than those without for each of the different underlying aetiologies. CONCLUSION Data from this pilot study demonstrate the potential use of this technique in risk stratification for the inherited cardiac conditions.
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Affiliation(s)
- Kevin Ming Wei Leong
- Institute of Cardiovascular Science, University College London & Bart's Heart Centre, Bart's Health NHS Trust, London, UK.,Imperial College Healthcare NHS Trust, London, UK
| | - Fu Siong Ng
- Institute of Cardiovascular Science, University College London & Bart's Heart Centre, Bart's Health NHS Trust, London, UK.,Imperial College Healthcare NHS Trust, London, UK
| | - Matthew J Shun-Shin
- Institute of Cardiovascular Science, University College London & Bart's Heart Centre, Bart's Health NHS Trust, London, UK.,Imperial College Healthcare NHS Trust, London, UK
| | - Michael Koa-Wing
- Institute of Cardiovascular Science, University College London & Bart's Heart Centre, Bart's Health NHS Trust, London, UK.,Imperial College Healthcare NHS Trust, London, UK
| | - Norman Qureshi
- Institute of Cardiovascular Science, University College London & Bart's Heart Centre, Bart's Health NHS Trust, London, UK.,Imperial College Healthcare NHS Trust, London, UK
| | - Zachary I Whinnett
- Institute of Cardiovascular Science, University College London & Bart's Heart Centre, Bart's Health NHS Trust, London, UK.,Imperial College Healthcare NHS Trust, London, UK
| | - Nick F Linton
- Institute of Cardiovascular Science, University College London & Bart's Heart Centre, Bart's Health NHS Trust, London, UK.,Imperial College Healthcare NHS Trust, London, UK
| | - David Lefroy
- Institute of Cardiovascular Science, University College London & Bart's Heart Centre, Bart's Health NHS Trust, London, UK.,Imperial College Healthcare NHS Trust, London, UK
| | - Darrel P Francis
- Institute of Cardiovascular Science, University College London & Bart's Heart Centre, Bart's Health NHS Trust, London, UK.,Imperial College Healthcare NHS Trust, London, UK
| | - Sian E Harding
- Institute of Cardiovascular Science, University College London & Bart's Heart Centre, Bart's Health NHS Trust, London, UK.,Imperial College Healthcare NHS Trust, London, UK
| | - D Wyn Davies
- Imperial College Healthcare NHS Trust, London, UK
| | - Nicholas S Peter
- Institute of Cardiovascular Science, University College London & Bart's Heart Centre, Bart's Health NHS Trust, London, UK.,Imperial College Healthcare NHS Trust, London, UK
| | - Phang Boon Lim
- Institute of Cardiovascular Science, University College London & Bart's Heart Centre, Bart's Health NHS Trust, London, UK.,Imperial College Healthcare NHS Trust, London, UK
| | - Elijah Behr
- St George's University Hospitals NHS Trust, London, UK
| | | | - Amanda Varnava
- Institute of Cardiovascular Science, University College London & Bart's Heart Centre, Bart's Health NHS Trust, London, UK.,Imperial College Healthcare NHS Trust, London, UK
| | - Prapa Kanagaratnam
- Institute of Cardiovascular Science, University College London & Bart's Heart Centre, Bart's Health NHS Trust, London, UK.,Imperial College Healthcare NHS Trust, London, UK
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5
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The Ventricular Ectopic QRS Interval: A Potential Marker for Ventricular Arrhythmia in Ischemic Heart Disease. JACC Clin Electrophysiol 2016; 2:587-595. [PMID: 29759578 DOI: 10.1016/j.jacep.2016.04.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Revised: 03/15/2016] [Accepted: 04/04/2016] [Indexed: 11/21/2022]
Abstract
OBJECTIVES The purpose of this study was to determine the potential value of a novel marker for the severity of structural heart disease and the risk of arrhythmia. BACKGROUND The ventricular ectopic QRS interval (VEQSI) has been shown to identify structural heart disease and predict mortality in an unselected population. In ischemic heart disease (IHD), risk stratification for sudden death is imperfect. We hypothesized that VEQSI would identify patients with prior myocardial infarction (MI) compared with healthy subjects and distinguish IHD patients who have suffered life-threatening events from those without prior significant ventricular arrhythmia. METHODS The 12-lead Holter recordings from 189 patients with previous MI were analyzed: 38 with prior ventricular tachycardia/ventricular fibrillation (MI-VT/VF) (66 ± 9 years; 92% male); 151 without prior significant ventricular arrhythmia (MI-no VT/VF) (64 ± 11 years; 74% male). These were compared with 60 healthy controls (62 ± 7 years; 70% male). All ventricular ectopic beats were reviewed and maximal VEQSI duration (VESQI max) was recorded as the duration of the longest ventricular ectopic beat. RESULTS VEQSI max was longer in post-MI patients compared with normal controls (185 ± 26 ms vs. 164 ± 16 ms; p < 0.001) and in MI-VT/VF patients with prior life-threatening events compared with MI-no VT/VF patients without prior life-threatening events (214 ± 20 ms vs. 177 ± 22 ms; p < 0.001). Multivariate analysis established VEQSI max as the strongest independent marker for prior serious ventricular arrhythmia. VEQSI max >198 ms had 86% sensitivity, 85% specificity, 62% positive predictive value, and 96% negative predictive value for identifying patients with prior life-threatening events (odds ratio: 37.4; 95% confidence interval: 13.0 to 107.5). CONCLUSIONS VEQSI max >198 ms distinguishes post-MI patients with prior life-threatening events from those without prior significant ventricular arrhythmia. This may be a useful additional index for risk stratification in IHD.
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6
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Tse G, Hothi SS, Grace AA, Huang CLH. Ventricular arrhythmogenesis following slowed conduction in heptanol-treated, Langendorff-perfused mouse hearts. J Physiol Sci 2012; 62:79-92. [PMID: 22219003 PMCID: PMC10717265 DOI: 10.1007/s12576-011-0187-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Accepted: 11/28/2011] [Indexed: 10/14/2022]
Abstract
Arrhythmogenic effects of slowed action potential conduction produced by the gap junction and sodium-channel inhibitor heptanol (0.1-2 mM) were explored in Langendorff-perfused mouse hearts. Monophasic action potential recordings showed that 2 mM heptanol induced ventricular tachycardia in the absence of triggered activity arising from early or after-depolarizations during regular 8 Hz pacing and programmed electrical stimulation (PES). It also increased activation latencies and ventricular effective refractory periods (VERPs), but did not alter action potential duration (APD), thereby reducing local critical intervals for re-excitation given by APD(90) - VERP. Bipolar electrogram recordings showed that 2 mM heptanol increased electrogram duration (EGD) and ratios of EGDs obtained at the longest to those obtained at the shortest S1S2 intervals studied during PES, suggesting increased dispersion of conduction velocities. These findings show, for the first time in the mouse heart, that slowed conduction induces reversible arrhythmogenic effects despite repolarization abnormalities expected to reduce arrhythmogenicity.
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Affiliation(s)
- Gary Tse
- Section of Cardiovascular Biology, Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW UK
| | - Sandeep S. Hothi
- The Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG UK
- Addenbrooke’s Hospital, Hills Road, Cambridge, CB2 0QQ UK
| | - Andrew A. Grace
- Section of Cardiovascular Biology, Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW UK
| | - Christopher L. -H. Huang
- Section of Cardiovascular Biology, Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW UK
- The Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG UK
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7
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Stein M, van Veen TAB, Hauer RNW, de Bakker JMT, van Rijen HVM. A 50% reduction of excitability but not of intercellular coupling affects conduction velocity restitution and activation delay in the mouse heart. PLoS One 2011; 6:e20310. [PMID: 21673812 PMCID: PMC3106008 DOI: 10.1371/journal.pone.0020310] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Accepted: 04/27/2011] [Indexed: 11/28/2022] Open
Abstract
Introduction Computer simulations suggest that intercellular coupling is more robust than membrane excitability with regard to changes in and safety of conduction. Clinical studies indicate that SCN5A (excitability) and/or Connexin43 (Cx43, intercellular coupling) expression in heart disease is reduced by approximately 50%. In this retrospective study we assessed the effect of reduced membrane excitability or intercellular coupling on conduction in mouse models of reduced excitability or intercellular coupling. Methods and Results Epicardial activation mapping of LV and RV was performed on Langendorff-perfused mouse hearts having the following: 1) Reduced excitability: Scn5a haploinsufficient mice; and 2) reduced intercellular coupling: Cx43CreER(T)/fl mice, uninduced (50% Cx43) or induced (10% Cx43) with Tamoxifen. Wild type (WT) littermates were used as control. Conduction velocity (CV) restitution and activation delay were determined longitudinal and transversal to fiber direction during S1S1 pacing and S1S2 premature stimulation until the effective refractory period. In both animal models, CV restitution and activation delay in LV were not changed compared to WT. In contrast, CV restitution decreased and activation delay increased in RV during conduction longitudinal but not transverse to fiber direction in Scn5a heterozygous animals compared to WT. In contrast, a 50% reduction of intercellular coupling did not affect either CV restitution or activation delay. A decrease of 90% Cx43, however, resulted in decreased CV restitution and increased activation delay in RV, but not LV. Conclusion Reducing excitability but not intercellular coupling by 50% affects CV restitution and activation delay in RV, indicating a higher safety factor for intercellular coupling than excitability in RV.
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Affiliation(s)
- Mèra Stein
- Division of Heart & Lungs, Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
- Division of Heart & Lungs, Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Toon A. B. van Veen
- Division of Heart & Lungs, Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Richard N. W. Hauer
- Division of Heart & Lungs, Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Jacques M. T. de Bakker
- Division of Heart & Lungs, Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
- Interuniversity Cardiology Institute of the Netherlands, Utrecht, The Netherlands
- Heart Failure Research Center, Academic Medical Center, Amsterdam, The Netherlands
| | - Harold V. M. van Rijen
- Division of Heart & Lungs, Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
- * E-mail:
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8
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Pytkowski M, Jankowska A, Maciag A, Kowalik I, Sterlinski M, Szwed H, Saumarez RC. Paroxysmal atrial fibrillation is associated with increased intra-atrial conduction delay. Europace 2008; 10:1415-20. [DOI: 10.1093/europace/eun282] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
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Saumarez RC, Pytkowski M, Sterlinski M, Bourke JP, Clague JR, Cobbe SM, Connelly DT, Griffith MJ, McKeown PP, McLeod K, Morgan JM, Sadoul N, Chojnowska L, Huang CLH, Grace AA. Paced ventricular electrogram fractionation predicts sudden cardiac death in hypertrophic cardiomyopathy. Eur Heart J 2008; 29:1653-61. [DOI: 10.1093/eurheartj/ehn111] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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10
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Bueno-Orovio A, Cherry EM, Fenton FH. Minimal model for human ventricular action potentials in tissue. J Theor Biol 2008; 253:544-60. [PMID: 18495166 DOI: 10.1016/j.jtbi.2008.03.029] [Citation(s) in RCA: 181] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Revised: 03/25/2008] [Accepted: 03/26/2008] [Indexed: 10/22/2022]
Abstract
Modeling the dynamics of wave propagation in human ventricular tissue and studying wave stability require models that reproduce realistic characteristics in tissue. We present a minimal ventricular (MV) human model that is designed to reproduce important tissue-level characteristics of epicardial, endocardial and midmyocardial cells, including action potential (AP) amplitudes and morphologies, upstroke velocities, steady-state action potential duration (APD) and conduction velocity (CV) restitution curves, minimum APD, and minimum diastolic interval. The model is then compared with three previously published human ventricular cell models, the Priebe and Beuckelmann (PB), the Ten Tusscher-Noble-Noble-Panfilov (TNNP), and the Iyer-Mazhari-Winslow (IMW). For the first time, the stability of reentrant waves for all four models is analyzed, and quantitative comparisons are made among the models in single cells and in tissue. The PB, TNNP, and IMW models exhibit quantitative differences in APD and CV rate adaptation, as well as completely different reentrant wave dynamics of quasi-breakup, stability, and breakup, respectively. All the models have dominant frequencies comparable to clinical values except for the IMW model, which has a large range of frequencies extending beyond the clinical range for both ventricular tachycardia (VT) and ventricular fibrillation (VF). The TNNP and IMW models possess a large degree of short-term memory and we show for the first time the existence of memory in CV restitution. The MV model also can be fitted to reproduce the dynamics of other models and is computationally more efficient: the times required to simulate the MV, TNNP, PB and IMW models follow the ratio 1:31:50:8084.
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Affiliation(s)
- Alfonso Bueno-Orovio
- Departamento de Matemáticas, Universidad de Castilla-La Mancha, Ciudad Real, Spain
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11
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Cha YM, Gersh BJ, Maron BJ, Boriani G, Spirito P, Hodge DO, Weivoda PL, Trusty JM, Friedman PA, Hammill SC, Rea RF, Shen WK. Electrophysiologic manifestations of ventricular tachyarrhythmias provoking appropriate defibrillator interventions in high-risk patients with hypertrophic cardiomyopathy. J Cardiovasc Electrophysiol 2007; 18:483-7. [PMID: 17343723 DOI: 10.1111/j.1540-8167.2007.00780.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
INTRODUCTION Our objective was to determine features of ventricular tachyarrhythmias triggering appropriate implantable cardioverter-defibrillator (ICD) interventions in hypertrophic cardiomyopathy (HCM). METHODS AND RESULTS The study cohort was 68 high-risk HCM patients who received ICDs for primary sudden cardiac death prevention from 1995 to 2003. All episodes of sustained ventricular tachyarrhythmias identified by stored intracardiac electrograms were analyzed. Nine patients had 51 episodes of sustained ventricular tachyarrhythmic events that required device therapy (mean follow-up, 3.4 +/- 2.2 years; cumulative event rate, 3.2% per year): five had 47 episodes of monomorphic ventricular tachycardia (VT); four each had one episode of ventricular fibrillation (VF). Sinus tachycardia or atrial fibrillation was the initiating rhythm in five of nine patients and in 43 of 51 episodes of events. Of the 17 episodes of monomorphic VT detected in the VT zone, 16 (94%) were terminated by antitachycardia pacing. Thirty episodes of monomorphic VT were detected in the VF zone and were terminated by defibrillation. CONCLUSION Sustained monomorphic VT is common in a high-risk cohort with HCM. Sinus tachycardia is often the initiating rhythm, suggesting that high sympathetic drive may be proarrhythmic when a susceptible substrate is present. Antitachycardia pacing is highly effective in terminating VT in this patient population.
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Affiliation(s)
- Yong-Mei Cha
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN 55905, USA
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Ohkubo K, Watanabe I, Takagi Y, Okumura Y, Ashino S, Kofune M, Kofune T, Shindo A, Sugimura H, Nakai T, Kunimoto S, Kasamaki Y, Saito S, Hirayama A. Endocardial Electrograms From the Right Ventricular Outflow Tract After Induced Ventricular Fibrillation in Patients With Brugada Syndrome. Circ J 2007; 71:1258-62. [PMID: 17652891 DOI: 10.1253/circj.71.1258] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND The pathogenesis of Brugada syndrome (BS) is reported to be phase 2 reentry resulting from shortening of the action potential duration at the epicardial site of the right ventricular outflow tract (RVOT). However, several reports have shown a high incidence of ventricular late potentials (LPs) and a high rate of induction of ventricular fibrillation (VF) by programmed ventricular stimulation (PVS) among patients with BS. The aim of this study was to investigate the role of slow conduction for the initiation of VF by PVS in these patients. METHODS AND RESULTS Endocardial mapping of the RVOT was conducted in 17 patients in whom VF was induced by PVS from the RV apex or RVOT; 11 patients had a positive LP. In 10 patients, RV mapping showed that low-amplitude fragmented and delayed potentials (DPs) were recorded at the RVOT below the pulmonary valve (PV) or between the PV and His bundle electrogram recording site. Electrograms recorded after PVS showed a high incidence of fractionated and disorganized DPs that lead to VF. CONCLUSIONS Slow conduction at the RVOT may contribute to the induction of VF by PVS. However, the role of slow conduction in spontaneous VF remains controversial.
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Affiliation(s)
- Kimie Ohkubo
- Division of Cardiology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan
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13
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Schueller PO, Hennersdorf MG, Strauer BE. Sudden death is associated with a widened paced QRS complex in noncoronary cardiac disease. J Interv Card Electrophysiol 2006; 15:125-30. [PMID: 16755342 DOI: 10.1007/s10840-006-8345-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2005] [Accepted: 03/17/2006] [Indexed: 11/28/2022]
Abstract
INTRODUCTION Recent experimental and clinical trials have provided evidence that increased duration of right ventricular electrogram in response to premature extrastimuli correlates with the risk of ventricular fibrillation in noncoronary heart disease. The aim of the present study was to investigate the duration of the surface QRS complex at short coupling intervals of extrastimuli as a new indicator for major arrhythmic events. METHODS 32 patients all with nonischemic heart diseases and well preserved left ventricular function in sinusrhythm were included into the study. Fifteen had witnessed sudden death due to ventricular fibrillation or polymorphic ventricular tachycardia (VF/VT group). The control group comprised seventeen patients without a history of ventricular arrhythmias (control group). All subjects underwent programmed ventricular stimulation and QRS-durations S1-S2-S3 directly above the ventricular refractory period were analyzed. RESULTS Both groups had a comparable basic QRS complex of 85 +/- 9 (VF/VT) vs. 87 +/- 13 ms (control), p = 0.83. The stimulated QRS complex S3 was significantly wider in the VF/VT group compared to the control group at pacing rates of 500 and 430 ms (500 ms: 256 +/- 22 vs. 235 +/- 32 ms, p = 0.04; 430 ms: 258 +/- 23 vs. 226 +/- 27 ms, p = 0.001). No differences with regard to the ventricular effective refractory period and the ventriculoatrial conduction could be observed beween the groups. CONCLUSIONS Our results indicate that the duration of the paced QRS complex may be a valuable parameter to predict arrhythmic risk in patients with nonischemic heart disease. Further prospective studies in larger trials are necessary to corroborate this investigation.
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Affiliation(s)
- Per Otto Schueller
- Department of Cardiology, Heinrich Heine University, Duesseldorf, Germany.
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Turner I, L-H Huang C, Saumarez RC. Numerical Simulation of Paced Electrogram Fractionation: Relating Clinical Observations to Changes in Fibrosis and Action Potential Duration. J Cardiovasc Electrophysiol 2005; 16:151-61. [PMID: 15720453 DOI: 10.1046/j.1540-8167.2005.30490.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
UNLABELLED Simulating paced electrogram fractionation. INTRODUCTION Paced electrogram fractionation analysis (PEFA) may identify a re-entrant substrate in patients at risk of ventricular fibrillation (VF) by detecting prolonged, fractionated ventricular electrograms ("fractionation") in response to premature extrastimuli. Numerical simulations of action potential (AP) propagation through human myocardium following such premature stimulation were performed to study the relationship between electrogram fractionation, fibrosis, and changes in AP currents. METHODS AND RESULTS Activation in a resistive monodomain 2 cm2 sheet of myocardium containing nonconducting fibrous tissue was modeled using standard numerical methods for solutions of partial differential equations using the Priebe-Beukelmann (PB) AP equations. Myocardial fibrosis significantly influenced electrogram morphology. High densities of closely spaced fibrous septa caused functional block and altered propagation paths at short coupling intervals, and produced large increases in electrogram duration similar to those associated with increased risk of VF in clinical studies. Prolongation of the cardiac AP using the heart failure variant of the PB model further increased the amount of fractionation and thereby replicated clinical recordings more closely than did fibrosis alone. Increasing AP dispersion by a variable reduction in the potassium current I(Kr) simulated results seen in patients with the long QT syndrome with an abrupt increase in electrogram duration, while a uniform reduction in I(Kr) alone did not result in fractionated electrograms. In contrast, increases in cytosolic Ca2+ and Ca2+ buffering by troponin to simulate HCM had little effect on fractionation. CONCLUSIONS These results relate the effects of fibrosis, AP abnormalities, and dispersion of AP duration to the characteristic electrograms recorded in patients at risk of sudden death.
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Affiliation(s)
- Ian Turner
- Papworth Hospital, University of Cambridge, United Kingdom
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15
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Bernus O, Wilders R, Zemlin CW, Verschelde H, Panfilov AV. A computationally efficient electrophysiological model of human ventricular cells. Am J Physiol Heart Circ Physiol 2002; 282:H2296-308. [PMID: 12003840 DOI: 10.1152/ajpheart.00731.2001] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recent experimental and theoretical results have stressed the importance of modeling studies of reentrant arrhythmias in cardiac tissue and at the whole heart level. We introduce a six-variable model obtained by a reformulation of the Priebe-Beuckelmann model of a single human ventricular cell. The reformulated model is 4.9 times faster for numerical computations and it is more stable than the original model. It retains the action potential shape at various frequencies, restitution of action potential duration, and restitution of conduction velocity. We were able to reproduce the main properties of epicardial, endocardial, and M cells by modifying selected ionic currents. We performed a simulation study of spiral wave behavior in a two-dimensional sheet of human ventricular tissue and showed that spiral waves have a frequency of 3.3 Hz and a linear core of approximately 50-mm diameter that rotates with an average frequency of 0.62 rad/s. Simulation results agreed with experimental data. In conclusion, the proposed model is suitable for efficient and accurate studies of reentrant phenomena in human ventricular tissue.
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Affiliation(s)
- O Bernus
- Department of Mathematical Physics and Astronomy, Gent University, 9000 Gent, Belgium.
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16
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Papadatos GA, Wallerstein PMR, Head CEG, Ratcliff R, Brady PA, Benndorf K, Saumarez RC, Trezise AEO, Huang CLH, Vandenberg JI, Colledge WH, Grace AA. Slowed conduction and ventricular tachycardia after targeted disruption of the cardiac sodium channel gene Scn5a. Proc Natl Acad Sci U S A 2002; 99:6210-5. [PMID: 11972032 PMCID: PMC122928 DOI: 10.1073/pnas.082121299] [Citation(s) in RCA: 294] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2001] [Accepted: 03/01/2002] [Indexed: 11/18/2022] Open
Abstract
Voltage-gated sodium channels drive the initial depolarization phase of the cardiac action potential and therefore critically determine conduction of excitation through the heart. In patients, deletions or loss-of-function mutations of the cardiac sodium channel gene, SCN5A, have been associated with a wide range of arrhythmias including bradycardia (heart rate slowing), atrioventricular conduction delay, and ventricular fibrillation. The pathophysiological basis of these clinical conditions is unresolved. Here we show that disruption of the mouse cardiac sodium channel gene, Scn5a, causes intrauterine lethality in homozygotes with severe defects in ventricular morphogenesis whereas heterozygotes show normal survival. Whole-cell patch clamp analyses of isolated ventricular myocytes from adult Scn5a(+/-) mice demonstrate a approximately 50% reduction in sodium conductance. Scn5a(+/-) hearts have several defects including impaired atrioventricular conduction, delayed intramyocardial conduction, increased ventricular refractoriness, and ventricular tachycardia with characteristics of reentrant excitation. These findings reconcile reduced activity of the cardiac sodium channel leading to slowed conduction with several apparently diverse clinical phenotypes, providing a model for the detailed analysis of the pathophysiology of arrhythmias.
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Affiliation(s)
- G Alex Papadatos
- Section of Cardiovascular Biology, Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, United Kingdom
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Tai CT, Chen SA, Tzeng JW, Kuo BI, Ding YA, Chang MS, Shyu LY. Prolonged fractionation of paced right atrial electrograms in patients with atrial flutter and fibrillation. J Am Coll Cardiol 2001; 37:1651-7. [PMID: 11345380 DOI: 10.1016/s0735-1097(01)01215-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVES This study investigated the extent of fractionation of paced right atrial electrograms in patients with and without paroxysmal atrial flutter (AFL) or atrial fibrillation (AF). BACKGROUND Slow conduction through nonuniform anisotropic atrial muscles, represented by fractionated electrograms, may favor the generation of atrial tachyarrhythmias. METHODS This study included 10 control patients (Group 1), 8 patients with documented paroxysmal AFL (Group 2) and 10 patients with documented paroxysmal AF (Group 3). Five electrode catheters were placed in the different sites of the right atrium and one catheter was positioned at the coronary sinus ostium. Atrial pacing from one site was done by a constant drive train with an extrastimulus inserted every fourth beat while recording at the other five sites was performed. The delay of each fractionated potential in the high-pass filtered atrial electrogram in response to extrastimulation was determined and used to construct conduction curves of delay versus the S1S2 interval. RESULTS The mean increase in electrogram duration between a coupling interval of 350 ms and 10 ms above atrial refractoriness was significantly greater in Groups 2 and 3 compared with that in Group 1 (8.5 +/- 2.5 vs. 11.0 +/- 2.7 vs. 5.9 +/- 2.3 ms, respectively, p < 0.001). The mean S1S2 interval at which delay increased suddenly was also longer in Groups 2 and 3 compared with Group 1 (326 +/- 9 vs. 343 +/- 12 vs. 307 +/- 17 ms, respectively, p < 0.001). CONCLUSIONS Increased delays in the individual potential of the fractionated atrial electrograms may be related to the development of AFL and AF.
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Affiliation(s)
- C T Tai
- Department of Medicine, National Yang-Ming University School of Medicine, Taipei Veterans General Hospital, Taiwan.
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Belhassen B, Viskin S, Fish R, Glick A, Setbon I, Eldar M. Effects of electrophysiologic-guided therapy with Class IA antiarrhythmic drugs on the long-term outcome of patients with idiopathic ventricular fibrillation with or without the Brugada syndrome. J Cardiovasc Electrophysiol 1999; 10:1301-12. [PMID: 10515552 DOI: 10.1111/j.1540-8167.1999.tb00183.x] [Citation(s) in RCA: 144] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
INTRODUCTION Implantation of a implantable cardioverter defibrillator (ICD) is viewed universally as the "gold standard" therapy for patients with idiopathic ventricular fibrillation (VF). We sought to study the long-term value of electrophysiologic (EP)-guided therapy with Class IA antiarrhythmic drugs in patients with idiopathic VF with or without the Brugada syndrome. METHODS AND RESULTS We performed EP studies in 34 consecutive patients who had idiopathic VF with (n = 5) or without (n = 29) the Brugada syndrome. All patients with inducible sustained polymorphic ventricular tachycardia (SPVT) or VF underwent repeated EP evaluation after oral administration of a Class IA antiarrhythmic drug (mainly quinidine). Patients rendered noninducible received this therapy on a long-term basis. SPVT/VF were induced in 27 (79.4%) patients at baseline studies. Class IA drugs effectively prevented induction of SPVT/VF in 26 (96%) patients. Of the 23 patients treated with these medications, no patient died or had a sustained ventricular arrhythmia during a mean follow-up period of 9.1 +/- 5.6 years (7 to 20 years in 15 patients). Two deaths occurred in patients without inducible SPVT/VF at baseline studies who had been treated empirically. CONCLUSION Our results suggest that EP-guided therapy with Class IA agents is a reasonable, safe, and effective approach for the long-term management of patients with idiopathic VF. A randomized prospective study of EP-guided Class IA therapy in patients with ICDs seems warranted.
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Affiliation(s)
- B Belhassen
- Department of Cardiology, Tel-Aviv Sourasky Medical Center, Israel.
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Affiliation(s)
- A A Grace
- Papworth Hospital, and Department of Biochemistry, University of Cambridge, UK
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20
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Viskin S, Belhassen B. Polymorphic ventricular tachyarrhythmias in the absence of organic heart disease: classification, differential diagnosis, and implications for therapy. Prog Cardiovasc Dis 1998; 41:17-34. [PMID: 9717857 DOI: 10.1016/s0033-0620(98)80020-0] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Different polymorphic ventricular tachyarrhythmias may cause syncope or cardiac arrest in patients with no heart disease: (1) Catecholamine-sensitive polymorphic ventricular tachycardia (VT) presents during childhood: the hallmark is the reproducible provocation of atrial and polymorphic ventricular arrhythmias during exercise, despite a normal QT. Beta-blockers are the treatment of choice. (2) In the long QT syndromes (LQTS), malfunction of ion channels leads to prolonged ventricular repolarization, early afterdepolarizations, and triggered ventricular arrhythmias. Therapeutic options include: beta-blockers, genotype-specific therapy, cardiac sympathetic denervation, and implantation of pacemakers or defibrillators. (3) The "short-coupled variant of torsade de pointes" is a malignant disease that shares several characteristics with idiopathic ventricular fibrillation. Although verapamil is frequently recommended, mortality rates remain high. (4) Idiopathic ventricular fibrillation (VF) with normal electrocardiogram (ECG) strikes young adults of both genders. In contrast to other polymorphic tachyarrhythmias, idiopathic VF is not generally related to stress. Also, familial involvement is rare. Therapeutic options include implantation of defibrillators and therapy with class 1A drugs. (5) The "Brugada syndrome" and the "syndrome of nocturnal sudden death" strike males almost exclusively. Right bundle branch block (RBBB) with ST elevation in the right precordial leads-the "Brugada sign"--is seen in the ECG of both patient populations. Implantation of defibrillators is recommended.
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Affiliation(s)
- S Viskin
- Department of Cardiology, Tel Aviv Sourasky-Medical Center, and Sackler-School of Medicine, Tel Aviv University, Israel
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21
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Peeters HA, Sippensgroenewegen A, Wever EF, Potse M, Daniëls MC, Grimbergen CA, Hauer RN, Robles de Medina EO. Electrocardiographic identification of abnormal ventricular depolarization and repolarization in patients with idiopathic ventricular fibrillation. J Am Coll Cardiol 1998; 31:1406-13. [PMID: 9581742 DOI: 10.1016/s0735-1097(98)00120-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVES We sought to gain more insight into the arrhythmogenic etiology of idiopathic ventricular fibrillation (VF) by assessing ventricular depolarization and repolarization properties by means of various electrocardiographic (ECG) techniques. BACKGROUND Idiopathic VF occurs in the absence of demonstrable structural heart disease. Abnormalities in ventricular depolarization or repolarization have been related to increased vulnerability to VF in various cardiac disorders and are possibly also present in patients with idiopathic VF. METHODS In 17 patients with a first episode of idiopathic VF, 62-lead body surface QRST integral maps, QT dispersion on the 12-lead ECG and XYZ-lead signal-averaged ECGs were computed. RESULTS All subjects of a healthy control group had a normal dipolar QRST integral map. In patients with idiopathic VF, either a normal dipolar map (29%,), a dipolar map with an abnormally large negative area on the right side of the thorax (24%) or a nondipolar map (47%) were recorded. Only four patients (24%) had increased QT dispersion on the 12-lead ECG and late potentials could be recorded in 6 (38%) of 16 patients. During a median follow-up duration of 56 months (range 9 to 136), a recurrent arrhythmic event occurred in 7 patients (41%), all of whom had an abnormal QRST integral map. Five of these patients had late potentials, and three showed increased QT dispersion on the 12-lead ECG. CONCLUSIONS In patients with idiopathic VF, ventricular areas of slow conduction, regionally delayed repolarization or dispersion in repolarization can be identified. Therefore, various electrophysiologic conditions, alone or in combination, may be responsible for the occurrence of idiopathic VF. Body surface QRST integral mapping may be a promising method to identify those patients who do not show a recurrent episode of VF.
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Affiliation(s)
- H A Peeters
- Department of Cardiology, Heart-Lung Institute, University Hospital Utrecht, The Netherlands.
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Tsai CF, Chen SA, Tai CT, Chiang CE, Ding YA, Chang MS. Idiopathic ventricular fibrillation: clinical, electrophysiologic characteristics and long-term outcomes. Int J Cardiol 1998; 64:47-55. [PMID: 9579816 DOI: 10.1016/s0167-5273(98)00004-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The long-term prognosis, including risks of arrhythmic recurrence of idiopathic ventricular fibrillation (VF), is uncertain; moreover, the role of electrophysiologic study in the diagnosis and guiding of antiarrhythmic drugs therapy for idiopathic VF remains controversial. The purpose of this study was to study the clinical features, electrophysiologic characteristics and long-term clinical outcomes of six consecutive patients (five males) who had at least one episode of aborted cardiac arrest (5 patients) or syncope (1 patients) with documentation of ventricular fibrillation (VF) in the absence of apparent heart disease. Idiopathic VF was diagnosed by exclusion. All patients underwent the electrophysiologic study including intravenous antiarrhythmic drug testing. Recurrences of VF after therapy and the long-term outcomes were assessed. The mean age at the first episode was 43+/-19 years (range from 16 to 63 years). All patients had sustained VF induced by double (3 patients) or triple (3 patients) ventricular extrastimuli at a paced cycle length of 400 or 500 ms from the right ventricular apex. Intravenous procainamide and/or mexiletine could suppress the reinduction of sustained VF in 4 (67%) of 6 patients. Recurrence of VF (documented VF attack, sudden cardiac arrest or syncope) was observed in 3 (100%) of 3 patients who received procainamide or mexiletine alone. Four patients (including 3 patients who experienced recurrence) received amiodarone alone or in combination with mexiletine, and these drugs could effectively prevent recurrence of VF. One patient with exercise-induced VF remained asymptomatic without any treatment during a follow-up period of 95 months. Another patient received an implantable cardioverter-defibrillator without concomitant antiarrhythmic drug therapy and had no discharge of electrical shock during 28 months of follow-up. During a mean follow-up period of 64+/-40 months (range from 28 to 128 months), all the patients were alive except patient No. 2 who died of acute hepatic failure. In conclusion, electrophysiologic study is a reliable diagnostic method, but it was of limited value in guiding antiarrhythmic drug therapy for preventing recurrence of idiopathic VF. Class I drug alone was associated with a high recurrence rate (100%) despite predictions that it would be effective by the electrophysiologic study. Amiodarone alone or in combination with mexiletine effectively prevented the recurrence of VF during the long-term follow-up along with a favourable outcome.
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Affiliation(s)
- C F Tsai
- Department of Medicine, National Yang-Ming University, School of Medicine, and Veterans General Hospital, Taipei, Taiwan, R.O.C
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Viskin S, Lesh MD, Eldar M, Fish R, Setbon I, Laniado S, Belhassen B. Mode of onset of malignant ventricular arrhythmias in idiopathic ventricular fibrillation. J Cardiovasc Electrophysiol 1997; 8:1115-20. [PMID: 9363814 DOI: 10.1111/j.1540-8167.1997.tb00997.x] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
INTRODUCTION The mode of onset of malignant ventricular arrhythmias (ventricular tachycardia [VT] or ventricular fibrillation [VF]) has been well described in patients with organic heart disease and in patients with the long QT syndromes. Less is known about the mode of onset of VF in patients with out-of-hospital VF who have no evidence of organic heart disease or identifiable etiology. METHODS AND RESULTS We reviewed the ECGs of all our patients with idiopathic VF. Documentation of the onset of spontaneous arrhythmias was available for 22 VF episodes in 9 patients (6 men and 3 women; age 41 +/- 16 years). In all instances, spontaneous VF followed a rapid polymorphic VT, which was initiated by premature ventricular complexes (PVCs) with very short coupling intervals. The PVC initiating VF had a coupling interval of 302 +/- 52 msec and a prematurity index of 0.4 +/- 0.07. These PVCs occurred within 40 msec of the peak of the preceding T wave. Pause-dependent arrhythmias were never observed. CONCLUSION Cardiac arrest among patients with idiopathic VF has a very distinctive mode of onset. Documentation of a polymorphic VT that is not pause dependent is of diagnostic value.
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Affiliation(s)
- S Viskin
- Department of Cardiology, Sourasky-Tel Aviv Medical Center, Sackler-School of Medicine, Tel Aviv University, Israel.
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