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Fairbank T, DeBauge A, Harvey CJ, Jiwani S, Ranka S, Beaver TA, Sheldon SH, Reddy M, Noheria A. Electrocardiographic Z-axis QRS-T voltage-time-integral in patients with typical right bundle branch block - Correlation with echocardiographic right ventricular size and function. J Electrocardiol 2024; 82:73-79. [PMID: 38043477 DOI: 10.1016/j.jelectrocard.2023.11.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 10/30/2023] [Accepted: 11/05/2023] [Indexed: 12/05/2023]
Abstract
BACKGROUND Right bundle branch block (RBBB) can be benign or associated with right ventricular (RV) functional and structural abnormalities. Our aim was to evaluate QRS-T voltage-time-integral (VTI) compared to QRS duration and lead V1 R' as markers for RV abnormalities. METHODS We included adults with an ECG demonstrating RBBB and echocardiogram obtained within 3 months of each other, between 2010 and 2020. VTIQRS and VTIQRST were obtained for 12 standard ECG leads, reconstructed vectorcardiographic X, Y, Z leads and root-mean-squared (3D) ECG. Age, sex and BSA-adjusted linear regressions were used to assess associations of QRS duration, amplitudes, VTIs and lead V1 R' duration/VTI with echocardiographic tricuspid annular plane systolic excursion (TAPSE), RV tissue Doppler imaging S', basal and mid diameter, and systolic pressure (RVSP). RESULTS Among 782 patients (33% women, age 71 ± 14 years) with RBBB, R' duration in lead V1 was modestly associated with RV S', RV diameters and RVSP (all p ≤ 0.03). QRS duration was more strongly associated with RV diameters (both p < 0.0001). AmplitudeQRS-Z was modestly correlated with all 5 RV echocardiographic variables (all p ≤ 0.02). VTIR'-V1 was more strongly associated with TAPSE, RV S' and RVSP (all p ≤ 0.0003). VTIQRS-Z and VTIQRST-Z were among the strongest correlates of the 5 RV variables (all p < 0.0001). VTIQRST-Z.√BSA cutoff of ≥62 μVsm had sensitivity 62.7% and specificity 65.7% for predicting ≥3 of 5 abnormal RV variables (AUC 0.66; men 0.71, women 0.60). CONCLUSION In patients with RBBB, VTIQRST-Z is a stronger predictor of RV dysfunction and adverse remodeling than QRS duration and lead V1 R'.
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Affiliation(s)
- Tyan Fairbank
- The University of Kansas School of Medicine, Kansas City, KS, United States of America
| | - Ashley DeBauge
- The University of Kansas School of Medicine, Kansas City, KS, United States of America
| | - Christopher J Harvey
- Department of Cardiovascular Medicine, The University of Kansas Medical Center, Kansas City, KS, United States of America
| | - Sania Jiwani
- Department of Cardiovascular Medicine, The University of Kansas Medical Center, Kansas City, KS, United States of America
| | - Sagar Ranka
- Division of Cardiology, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America
| | - Timothy A Beaver
- Department of Cardiovascular Medicine, The University of Kansas Medical Center, Kansas City, KS, United States of America
| | - Seth H Sheldon
- Department of Cardiovascular Medicine, The University of Kansas Medical Center, Kansas City, KS, United States of America
| | - Madhu Reddy
- Department of Cardiovascular Medicine, The University of Kansas Medical Center, Kansas City, KS, United States of America
| | - Amit Noheria
- Department of Cardiovascular Medicine, The University of Kansas Medical Center, Kansas City, KS, United States of America.
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DeBauge A, Fairbank T, Harvey CJ, Ranka S, Jiwani S, Sheldon SH, Reddy M, Beaver TA, Noheria A. Electrocardiographic prediction of left ventricular hypertrophy in women and men with left bundle branch block - Comparison of QRS duration, amplitude and voltage-time-integral. J Electrocardiol 2023; 80:34-39. [PMID: 37178633 PMCID: PMC10846562 DOI: 10.1016/j.jelectrocard.2023.03.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 03/01/2023] [Accepted: 03/07/2023] [Indexed: 03/16/2023]
Abstract
BACKGROUND Standard ECG criteria for left ventricular (LV) hypertrophy rely on QRS amplitudes. However, in the setting of left bundle branch block (LBBB), ECG correlates of LV hypertrophy are not well established. We sought to evaluate quantitative ECG predictors of LV hypertrophy in the presence of LBBB. METHODS We included adult patients with typical LBBB having ECG and transthoracic echocardiogram performed within 3 months of each other in 2010-2020. Orthogonal X, Y, Z leads were reconstructed from digital 12‑lead ECGs using Kors's matrix. In addition to QRS duration, we evaluated QRS amplitudes and voltage-time-integrals (VTIs) from all 12 leads, X, Y, Z leads and 3D (root-mean-squared) ECG. We used age, sex and BSA-adjusted linear regressions to predict echocardiographic LV calculations (mass, end-diastolic and end-systolic volumes, ejection fraction) from ECG, and separately generated ROC curves for predicting echocardiographic abnormalities. RESULTS We included 413 patients (53% women, age 73 ± 12 years). All 4 echocardiographic LV calculations were most strongly correlated with QRS duration (all p < 0.00001). In women, QRS duration ≥ 150 ms had sensitivity/specificity 56.3%/64.4% for increased LV mass and 62.7%/67.8% for increased LV end-diastolic volume. In men, QRS duration ≥ 160 ms had a sensitivity/specificity 63.1%/72.1% for increased LV mass and 58.3%/74.5% for increased LV end-diastolic volume. QRS duration was best able to discriminate eccentric hypertrophy (area under ROC curve 0.701) and increased LV end-diastolic volume (0.681). CONCLUSIONS In patients with LBBB, QRS duration (≥ 150 in women and ≥ 160 in men) is a superior predictor of LV remodeling esp. eccentric hypertrophy and dilation.
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Affiliation(s)
- Ashley DeBauge
- The University of Kansas School of Medicine, Kansas City, KS, United States of America
| | - Tyan Fairbank
- The University of Kansas School of Medicine, Kansas City, KS, United States of America
| | - Christopher J Harvey
- Department of Cardiovascular Medicine, The University of Kansas Medical Center, Kansas City, KS, United States of America
| | - Sagar Ranka
- Division of Cardiology, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America
| | - Sania Jiwani
- Department of Cardiovascular Medicine, The University of Kansas Medical Center, Kansas City, KS, United States of America
| | - Seth H Sheldon
- Department of Cardiovascular Medicine, The University of Kansas Medical Center, Kansas City, KS, United States of America
| | - Madhu Reddy
- Department of Cardiovascular Medicine, The University of Kansas Medical Center, Kansas City, KS, United States of America
| | - Timothy A Beaver
- Department of Cardiovascular Medicine, The University of Kansas Medical Center, Kansas City, KS, United States of America
| | - Amit Noheria
- Department of Cardiovascular Medicine, The University of Kansas Medical Center, Kansas City, KS, United States of America.
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Left bundle branch block without a typical contraction pattern is associated with increased risk of ventricular arrhythmias in cardiac resynchronization therapy patients. Int J Cardiovasc Imaging 2021; 37:1843-1851. [PMID: 33755881 DOI: 10.1007/s10554-021-02157-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 01/03/2021] [Indexed: 11/27/2022]
Abstract
Cardiac resynchronization therapy (CRT) reduces the risk of ventricular arrhythmias (VA) in heart failure (HF) patients with left bundle branch block (LBBB) while the effect is less clear among non-LBBB patients. This study aimed to investigate if absence of LBBB features whether by echocardiography or strict ECG criteria would identify patients at risk of developing VA in a cohort with LBBB according to conventional ECG criteria. Two hundred six CRT candidates were prospectively included from 2 centers. Prior to CRT presence of a typical LBBB contraction pattern was identified using longitudinal strain in the apical 4-chamber view. All preimplantation ECGs were categorized as LBBB or non-LBBB according to Strauss´ strict criteria. Primary end-point was defined as any appropriate antitachycardia pacing (ATP) or shock therapy within 2 years after CRT implantation. A total of 129 (63%) patients had a typical LBBB contraction pattern, while 134 (66%) met the strict ECG criteria. Over 2 years, 45 patients (22%) experienced VA. Absence of a typical LBBB contraction pattern was independently associated with an increased risk of VA (hazard ratio ([HR] 1.89; 95% CI 1.04 to 3.44; p: 0.036). Strict LBBB was not independently associated with the occurrence of VA. Fulfilling neither strict ECG nor echocardiographic criteria for LBBB was associated with a 3.3-fold increase in risk of VA ([HR] 3.34; 95% CI 1.75 to 6.94; (p < 0.001). The risk of VA was almost 2-fold higher if a typical LBBB contraction pattern was absent prior to CRT.
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Bacharova L, Moreira DAR. Contribution of altered working myocardium to intraventricular conduction disturbances. J Electrocardiol 2021; 66:23. [PMID: 33711717 DOI: 10.1016/j.jelectrocard.2021.02.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 02/24/2021] [Accepted: 02/25/2021] [Indexed: 11/30/2022]
Affiliation(s)
- Ljuba Bacharova
- International Laser Center CVTI, Bratislava, Slovak Republic.
| | - Dalmo A R Moreira
- Electrophysiology Section, Dante Pazzanese Institute of Cardiology, São Paulo, Brazil
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Corbisiero R, Mathew A, Bickert C, Muller D. Multipoint Pacing with Fusion-optimized Cardiac Resynchronization Therapy: Using It All to Narrow QRS Duration. J Innov Card Rhythm Manag 2021; 12:4355-4362. [PMID: 33520350 PMCID: PMC7834044 DOI: 10.19102/icrm.2021.120102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 08/18/2020] [Indexed: 11/25/2022] Open
Abstract
Adaptive atrioventricular (AV)-shortening algorithms have achieved QRS duration (QRSd) narrowing in traditional cardiac resynchronization therapy (CRT) patients. Multipoint pacing (MPP) has also demonstrated benefit in this population. An additional site of activation via intrinsic conduction of the septum may further contribute to CRT; however, the incorporation of all strategies together has yet to be explored. We therefore developed and tested a method combining MPP-CRT and controlled septal contribution to create a multifuse pacing (MFP) technique, establishing four ventricular activation sites for CRT patients using measurements from intracardiac electrograms (EGMs) and incorporating an AV-delay shortening algorithm (SyncAV™; Abbott Laboratories, Chicago, IL, USA) to narrow the QRSd. Patients in sinus rhythm with an AV conduction time of less than 350 ms were included in this analysis and were further stratified by strictly defined left bundle branch block (sLBBB) or nonspecific intraventricular conduction delay (IVCD). EGM-based measurements to determine the QRS septal onset to right ventricular (RV) time (SRAT) and the left ventricular (LV) to RV pacing conduction time were collected and applied to a formula to facilitate MFP. QRSd was compared between before and after programming. A total of 22 patients (19 men and three women) with similar baseline characteristics were compared (all values in mean ± standard deviation). The overall baseline QRSd of 153.31 ± 24.60 ms was decreased to 115.31 ± 16.31 ms after MFP programming (p < 0.0001). The measured SRAT was 59.40 ± 28.49 ms, resulting in a negative AV offset of −20.0 ± 24.97 ms. Patients in the sLBBB group (n = 7) were aged 67.8 ± 13.3 years and had a QRSd of 168.85 ± 27.29 ms that decreased to 113 ± 16.69 ms for a reduction of 55.42 ± 19.3 ms or 32.1% (p = 0.0003). In the IVCD group (n = 15), the baseline QRSd of 146.06 ± 20.29 ms was decreased to 116 ± 16.66 ms for a reduction of 30.07 ± 16.41 ms or 20.62% (p = 0.0001). When comparing the sLBBB and IVCD groups, the sLBBB group was favored by a reduction of 25.35 ms (p = 0.00046). Ultimately, MFP achieved statistically significant reductions in QRSd in all patients tested in this analysis. The benefit was also significantly better in the sLBBB group as compared with in the IVCD group.
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Prognostic value and prevalence of complete right bundle branch block in an elderly population: a community-based 10-year prospective study. Aging (Albany NY) 2020; 12:19073-19082. [PMID: 33021491 PMCID: PMC7732323 DOI: 10.18632/aging.103702] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 07/06/2020] [Indexed: 01/24/2023]
Abstract
Complete right bundle branch block (CRBBB) occurs in 0.2% to 1.3% of the general population, but its prognostic significance in the geriatric population is unknown. We prospectively investigated the prevalence and prognostic value of CRBBB in individuals aged ≥65 years in a community-based population in Taiwan. A total of 5,830 community-dwelling individuals were prospectively recruited from 7 regions across Taiwan starting in December 2008 through March 2013. Those aged ≥65 years were included in the analysis (N=3,383). All subjects underwent a home visit and standardized medical exams and were followed up annually until the end of April 2019; cause of death was documented by citizen death records. The mean age of the study cohort was 73.5±5.9 years (65-104), and 47.21% were men. Among these individuals, 171 (5.05%) had CRBBB; the prevalence was higher in men (7.08%) than in women (3.25%). Subjects with CRBBB were older than those without CRBBB (75.4±6.5 vs. 73.4±5.9), and the frequency of CRBBB increased with age. Survival analysis revealed that all-cause mortality and cardiac mortality were similar in individuals with and without CRBBB during a mean follow-up of 92.6±23.6 months. CRBBB is not associated with increased risk of mortality in the geriatric population.
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Moriña‐Vázquez P, Moraleda‐Salas MT, Arce‐León Á, Fernández‐Gómez JM, Venegas‐Gamero J, Díaz‐Fernández JF. Electrocardiographic patterns predictive of left bundle branch block correction with His bundle pacing. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2020; 43:1318-1324. [DOI: 10.1111/pace.14021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 07/17/2020] [Accepted: 07/26/2020] [Indexed: 11/26/2022]
Affiliation(s)
- Pablo Moriña‐Vázquez
- Arrhythmia Unit, Department of Cardiology Hospital Juan Ramon Jimenez Huelva Spain
| | | | - Álvaro Arce‐León
- Arrhythmia Unit, Department of Cardiology Hospital Juan Ramon Jimenez Huelva Spain
| | | | - José Venegas‐Gamero
- Arrhythmia Unit, Department of Cardiology Hospital Juan Ramon Jimenez Huelva Spain
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Bacharova L. Missing Link between Molecular Aspects of Ventricular Arrhythmias and QRS Complex Morphology in Left Ventricular Hypertrophy. Int J Mol Sci 2019; 21:E48. [PMID: 31861705 PMCID: PMC6982310 DOI: 10.3390/ijms21010048] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 12/17/2019] [Accepted: 12/17/2019] [Indexed: 12/27/2022] Open
Abstract
The aim of this opinion paper is to point out the knowledge gap between evidence on the molecular level and clinical diagnostic possibilities in left ventricular hypertrophy (LVH) regarding the prediction of ventricular arrhythmias and monitoring the effect of therapy. LVH is defined as an increase in left ventricular size and is associated with increased occurrence of ventricular arrhythmia. Hypertrophic rebuilding of myocardium comprises interrelated processes on molecular, subcellular, cellular, tissue, and organ levels affecting electrogenesis, creating a substrate for triggering and maintaining arrhythmias. The knowledge of these processes serves as a basis for developing targeted therapy to prevent and treat arrhythmias. In the clinical practice, the method for recording electrical phenomena of the heart is electrocardiography. The recognized clinical electrocardiogram (ECG) predictors of ventricular arrhythmias are related to alterations in electrical impulse propagation, such as QRS complex duration, QT interval, early repolarization, late potentials, and fragmented QRS, and they are not specific for LVH. However, the simulation studies have shown that the QRS complex patterns documented in patients with LVH are also conditioned remarkably by the alterations in impulse propagation. These QRS complex patterns in LVH could be potentially recognized for predicting ventricular arrhythmia and for monitoring the effect of therapy.
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Affiliation(s)
- Ljuba Bacharova
- International Laser Center, 841 04 Bratislava, Slovakia
- Institute of Pathophysiology, Medical School, Comenius University, 841 04 Bratislava, Slovakia
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Wieslander B, Xia X, Jablonowski R, Axelsson J, Klem I, Nijveldt R, Maynard C, Schelbert EB, Sörensson P, Sigfridsson A, Chaudhry U, Platonov PG, Borgquist R, Engblom H, Couderc JP, Strauss DG, Atwater BD, Ugander M. The ability of the electrocardiogram in left bundle branch block to detect myocardial scar determined by cardiovascular magnetic resonance. J Electrocardiol 2018; 51:779-786. [PMID: 30177312 DOI: 10.1016/j.jelectrocard.2018.05.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 05/19/2018] [Accepted: 05/29/2018] [Indexed: 12/24/2022]
Abstract
AIMS We aimed to improve the electrocardiographic 2009 left bundle branch block (LBBB) Selvester QRS score (2009 LBSS) for scar assessment. METHODS We retrospectively identified 325 LBBB patients with available ECG and cardiovascular magnetic resonance imaging (CMR) with late gadolinium enhancement from four centers (142 [44%] with CMR scar). Forty-four semi-automatically measured ECG variables pre-selected based on the 2009 LBSS yielded one multivariable model for scar detection and another for scar quantification. RESULTS The 2009 LBSS achieved an area under the curve (AUC) of 0.60 (95% confidence interval 0.54-0.66) for scar detection, and R2 = 0.04, p < 0.001, for scar quantification. Multivariable modeling improved scar detection to AUC 0.72 (0.66-0.77) and scar quantification to R2 = 0.21, p < 0.001. CONCLUSIONS The 2009 LBSS detects and quantifies myocardial scar with poor accuracy. Improved models with extensive comparison of ECG and CMR had modest performance, indicating limited room for improvement of the 2009 LBSS.
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Affiliation(s)
- Björn Wieslander
- Department of Clinical Physiology, Karolinska Institute, Karolinska University Hospital, Stockholm, Sweden
| | - Xiaojuan Xia
- Heart Research Follow-Up Program, University of Rochester, NY, USA
| | - Robert Jablonowski
- Department of Clinical Physiology and Nuclear Medicine, Skåne University Hospital, Lund University, Lund, Sweden
| | - Jimmy Axelsson
- Department of Clinical Physiology, Karolinska Institute, Karolinska University Hospital, Stockholm, Sweden
| | - Igor Klem
- Division of Cardiology, Duke University Medical Center, Durham, NC, USA
| | - Robin Nijveldt
- Department of Cardiology, VU University Medical Center, Amsterdam, the Netherlands
| | - Charles Maynard
- Department of Health Services, University of Washington, Seattle, WA, USA
| | | | - Peder Sörensson
- Department of Clinical Physiology, Karolinska Institute, Karolinska University Hospital, Stockholm, Sweden; Department of Cardiology, Karolinska University Hospital, Stockholm, Sweden
| | - Andreas Sigfridsson
- Department of Clinical Physiology, Karolinska Institute, Karolinska University Hospital, Stockholm, Sweden
| | - Uzma Chaudhry
- Arrhythmia Clinic, Skane University Hospital, Department of Cardiology, Clinical Sciences, Lund University, Lund, Sweden
| | - Pyotr G Platonov
- Arrhythmia Clinic, Skane University Hospital, Department of Cardiology, Clinical Sciences, Lund University, Lund, Sweden
| | - Rasmus Borgquist
- Arrhythmia Clinic, Skane University Hospital, Department of Cardiology, Clinical Sciences, Lund University, Lund, Sweden
| | - Henrik Engblom
- Department of Clinical Physiology and Nuclear Medicine, Skåne University Hospital, Lund University, Lund, Sweden
| | | | - David G Strauss
- Department of Clinical Physiology, Karolinska Institute, Karolinska University Hospital, Stockholm, Sweden; Division of Applied Regulatory Science, Office of Clinical Pharmacology, Office of Translational Sciences, Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, MD, USA
| | - Brett D Atwater
- Division of Cardiology, Duke University Medical Center, Durham, NC, USA
| | - Martin Ugander
- Department of Clinical Physiology, Karolinska Institute, Karolinska University Hospital, Stockholm, Sweden.
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Leonelli FM, Bagliani G, De Ponti R, Padeletti L. Intraventricular Delay and Blocks. Card Electrophysiol Clin 2018; 10:211-231. [PMID: 29784481 DOI: 10.1016/j.ccep.2018.02.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
From the atrioventricular node, electrical activation is propagated to both ventricles by a system of specialized conducting fibers, His Purkinje System (HPS), guaranteeing a fast, synchronous depolarization of both ventricles. From the predivisional common stem, a right and left branch separate, subdividing further in a fairly predictable fashion. Synchronous ventricular activation results in a QRS with specific characteristics and duration of less than 110 milliseconds. Block or delay in any part of the HPS changes the electrocardiographic (ECG) morphology. This article discusses the use and limitations of standard ECG in detecting abnormal ventricular propagation in specific areas of the HPS.
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Affiliation(s)
- Fabio M Leonelli
- Cardiology Department, James A. Haley Veterans' Hospital, University of South Florida, Tampa, FL, USA.
| | - Giuseppe Bagliani
- Cardiology Department, Arrhythmology Unit, Foligno General Hospital, Foligno, Italy; Cardiovascular Diseases Department, University of Perugia, Perugia, Italy
| | | | - Luigi Padeletti
- Heart and Vessels Department, University of Florence, Florence, Italy; IRCCS Multimedica, Sesto San Giovanni, Italy
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Gao Y, Xia L, Gong YL, Zheng DC. Electrocardiogram (ECG) patterns of left anterior fascicular block and conduction impairment in ventricular myocardium: a whole-heart model-based simulation study. J Zhejiang Univ Sci B 2018; 19:49-56. [PMID: 29308607 DOI: 10.1631/jzus.b1700029] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Left anterior fascicular block (LAFB) is a heart disease identifiable from an abnormal electrocardiogram (ECG). It has been reported that LAFB is associated with an increased risk of heart failure. Non-specific intraventricular conduction delay due to the lesions of the conduction bundles and slow cell to cell conduction has also been considered as another cause of heart failure. Since the location and mechanism of conduction delay have notable variability between individual patients, we hypothesized that the impaired conduction in the ventricular myocardium may lead to abnormal ECGs similar to LAFB ECG patterns. To test this hypothesis, based on a computer model with a three dimensional whole-heart anatomical structure, we simulated the cardiac exciting sequence map and 12-lead ECG caused by the block in the left anterior fascicle and by the slowed conduction velocity in the ventricular myocardium. The simulation results showed that the typical LAFB ECG patterns can also be observed from cases with slowed conduction velocity in the ventricular myocardium. The main differences were the duration of QRS and wave amplitude. In conclusion, our simulations provide a promising starting point to further investigate the underlying mechanism of heart failure with LAFB, which would provide a potential reference for LAFB diagnosis.
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Affiliation(s)
- Yuan Gao
- Department of Biomedical Engineering, Zhejiang University, Hangzhou 310027, China
| | - Ling Xia
- Department of Biomedical Engineering, Zhejiang University, Hangzhou 310027, China
| | - Ying-Lan Gong
- Department of Biomedical Engineering, Zhejiang University, Hangzhou 310027, China
| | - Ding-Chang Zheng
- Health and Wellbeing Academy, Faculty of Medical Science, Anglia Ruskin University, Chelmsford, CM1 1SQ, UK
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Risum N, Tayal B, Hansen TF, Bruun NE, Jensen MT, Lauridsen TK, Saba S, Kisslo J, Gorcsan J, Sogaard P. Identification of Typical Left Bundle Branch Block Contraction by Strain Echocardiography Is Additive to Electrocardiography in Prediction of Long-Term Outcome After Cardiac Resynchronization Therapy. J Am Coll Cardiol 2016; 66:631-41. [PMID: 26248989 DOI: 10.1016/j.jacc.2015.06.020] [Citation(s) in RCA: 120] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 05/07/2015] [Accepted: 06/02/2015] [Indexed: 11/26/2022]
Abstract
BACKGROUND Current guidelines suggest that patients with left bundle branch block (LBBB) be treated with cardiac resynchronization therapy (CRT); however, one-third do not have a significant activation delay, which can result in nonresponse. By identifying characteristic opposing wall contraction, 2-dimensional strain echocardiography (2DSE) may detect true LBBB activation. OBJECTIVES This study sought to investigate whether the absence of a typical LBBB mechanical activation pattern by 2DSE was associated with unfavorable long-term outcome and if this is additive to electrocardiographic (ECG) morphology and duration. METHODS From 2 centers, 208 CRT candidates (New York Heart Association classes II to IV, ejection fraction ≤35%, QRS duration ≥120 ms) with LBBB by ECG were prospectively included. Before CRT implantation, longitudinal strain in the apical 4-chamber view determined whether typical LBBB contraction was present. The pre-defined outcome was freedom from death, left ventricular assist device, or heart transplantation over 4 years. RESULTS Two-thirds of patients (63%) had a typical LBBB contraction pattern. During 4 years, 48 patients (23%) reached the primary endpoint. Absence of a typical LBBB contraction was independently associated with increased risk of adverse outcome after adjustment for ischemic heart disease and QRS width (hazard ratio [HR]: 3.1; 95% CI: 1.64 to 5.88; p < 0.005). Adding pattern assessment to a risk prediction model including QRS duration and ischemic heart disease significantly improved the net reclassification index to 0.14 (p = 0.04) and improved the C-statistics (0.63 [95% CI: 0.54 to 0.72] vs. 0.71 [95% CI: 0.63 to 0.80]; p = 0.02). Use of strict LBBB ECG criteria was not independently associated with outcome in the multivariate model (HR: 1.72; 95% CI: 0.89 to 3.33; p = 0.11. Assessment of LBBB contraction pattern was superior to time-to-peak indexes of dyssynchrony (p < 0.01 for all). CONCLUSIONS Contraction pattern assessment to identify true LBBB activation provided important prognostic information in CRT candidates.
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Affiliation(s)
- Niels Risum
- Department of Cardiology, Rigshospitalet Copenhagen University Hospital, Copenhagen, Denmark.
| | - Bhupendar Tayal
- Division of Cardiology, University of Pittsburgh, Pittsburgh, Pennsylvania; Department of Cardiology and Clinical Medicine, Aalborg University Hospital, Aalborg, Denmark
| | - Thomas F Hansen
- Department of Cardiology, Gentofte University Hospital, Hellerup, Denmark
| | - Niels E Bruun
- Division of Cardiology, University of Pittsburgh, Pittsburgh, Pennsylvania; Department of Cardiology, Gentofte University Hospital, Hellerup, Denmark
| | | | - Trine K Lauridsen
- Department of Cardiology, Gentofte University Hospital, Hellerup, Denmark
| | - Samir Saba
- Division of Cardiology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Joseph Kisslo
- Division of Cardiovascular Medicine, Duke University Medical Center, Durham, North Carolina
| | - John Gorcsan
- Division of Cardiology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Peter Sogaard
- Department of Cardiology and Clinical Medicine, Aalborg University Hospital, Aalborg, Denmark
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Bacharova L, Estes HE, Schocken DD, Ugander M, Soliman EZ, Hill JA, Bang LE, Schlegel TT. The 4th Report of the Working Group on ECG diagnosis of Left Ventricular Hypertrophy. J Electrocardiol 2016; 50:11-15. [PMID: 27890283 DOI: 10.1016/j.jelectrocard.2016.11.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Indexed: 12/18/2022]
Abstract
The 4th Report provides a brief review of publications focused on the electrocardiographic diagnosis of left ventricular hypertrophy published during the period of 2010 to 2016 by the members of the Working Group on ECG diagnosis of Left Ventricular Hypertrophy. The Working Group recommended that ECG research and clinical attention be redirected from the estimation of LVM to the identification of electrical remodeling, to better understanding the sequence of events connecting electrical remodeling to outcomes. The need for a re-definition of terms and for a new paradigm is also stressed.
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Affiliation(s)
- Ljuba Bacharova
- International Laser Center, Bratislava, Slovak Republic; Institute of Pathophysiology, Medical School, Comenius University, Bratislava, Slovak Republic.
| | - Harvey E Estes
- Department of Community and Family Medicine, Duke University Medical Center, Durham, NC, USA
| | | | - Martin Ugander
- Department of Clinical Physiology, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden
| | - Elsayed Z Soliman
- Epidemiological Cardiology Research Center (EPICARE), Division of Public Health Sciences, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Joseph A Hill
- Department of Internal Medicine, Cardiology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Lia E Bang
- Copenhagen University Hospital, Rigshospitalet, The Heart Center, Department of Cardiology, Denmark
| | - Todd T Schlegel
- Department of Clinical Physiology, Karolinska University Hospital and Karolinska Institute, Stockholm, Sweden; Nicollier-Schlegel SARL, Trélex, Switzerland
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Bacharova L, Szathmary V, Svehlikova J, Mateasik A, Tysler M. QRS complex waveform indicators of ventricular activation slowing: Simulation studies. J Electrocardiol 2016; 49:790-793. [DOI: 10.1016/j.jelectrocard.2016.07.032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Indexed: 11/15/2022]
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Engels EB, Mafi-Rad M, van Stipdonk AMW, Vernooy K, Prinzen FW. Why QRS Duration Should Be Replaced by Better Measures of Electrical Activation to Improve Patient Selection for Cardiac Resynchronization Therapy. J Cardiovasc Transl Res 2016; 9:257-65. [PMID: 27230674 PMCID: PMC4990608 DOI: 10.1007/s12265-016-9693-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 04/25/2016] [Indexed: 11/28/2022]
Abstract
Cardiac resynchronization therapy (CRT) is a well-known treatment modality for patients with a reduced left ventricular ejection fraction accompanied by a ventricular conduction delay. However, a large proportion of patients does not benefit from this therapy. Better patient selection may importantly reduce the number of non-responders. Here, we review the strengths and weaknesses of the electrocardiogram (ECG) markers currently being used in guidelines for patient selection, e.g., QRS duration and morphology. We shed light on the current knowledge on the underlying electrical substrate and the mechanism of action of CRT. Finally, we discuss potentially better ECG-based biomarkers for CRT candidate selection, of which the vectorcardiogram may have high potential.
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Affiliation(s)
- Elien B Engels
- Department of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | - Masih Mafi-Rad
- Department of Cardiology, Maastricht University Medical Center, Maastricht, The Netherlands
| | | | - Kevin Vernooy
- Department of Cardiology, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Frits W Prinzen
- Department of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands.
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Cardiac resynchronization therapy: Identifying an activation delay by regional strain analysis. J Electrocardiol 2015; 48:779-82. [DOI: 10.1016/j.jelectrocard.2015.07.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Indexed: 11/19/2022]
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Mafi Rad M, Wijntjens GWM, Engels EB, Blaauw Y, Luermans JGLM, Pison L, Crijns HJ, Prinzen FW, Vernooy K. Vectorcardiographic QRS area identifies delayed left ventricular lateral wall activation determined by electroanatomic mapping in candidates for cardiac resynchronization therapy. Heart Rhythm 2015; 13:217-25. [PMID: 26232766 DOI: 10.1016/j.hrthm.2015.07.033] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Indexed: 11/26/2022]
Abstract
BACKGROUND Delayed left ventricular (LV) lateral wall (LVLW) activation is considered the electrical substrate underlying LV dysfunction amenable to cardiac resynchronization therapy (CRT). OBJECTIVE The purpose of this study was to assess LVLW activation in CRT candidates using coronary venous electroanatomic mapping (EAM) and to investigate whether the QRS area (QRSAREA) on the vectorcardiogram (VCG) can identify delayed LVLW activation. METHODS Fifty-one consecutive CRT candidates (29 left bundle branch block [LBBB], 15 intraventricular conduction delay [IVCD], 7 right bundle branch block [RBBB]) underwent intraprocedural coronary venous EAM using EnSite NavX. VCGs were constructed from preprocedural digital 12-lead ECGs using the Kors method. QRSAREA was assessed and compared to QRS duration and 5 different LBBB definitions. RESULTS Delayed LVLW activation (activation time >75% of QRS duration) occurred in 38 of 51 patients (29/29 LBBB, 8/15 IVCD, 1/7 RBBB). QRSAREA was larger in patients with than in patients without delayed LVLW activation (108 ± 42 µVs vs 51 ± 27 µVs, P < .001), and identified delayed LVLW activation better than QRS duration (area under the curve 0.89 [95% confidence interval 0.79-0.99] vs 0.49 [95% confidence interval 0.33-0.65]). QRSAREA >69 µVs diagnosed delayed LVLW activation with a higher sum of sensitivity (87%) and specificity (92%) than any of the LBBB definitions. Of the different LBBB definitions, the European Society of Cardiology textbook definition performed best with sensitivity of 76% and specificity of 100%. CONCLUSION Coronary venous EAM can be used during CRT implantation to determine the presence of delayed LVLW activation. QRSAREA is a noninvasive alternative for intracardiac measurements of electrical activation, which identifies delayed LVLW activation better than QRS duration and LBBB morphology.
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Affiliation(s)
- Masih Mafi Rad
- Department of Cardiology, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Gilbert W M Wijntjens
- Department of Physiology, Maastricht University, Cardiovascular Research Institute Maastricht (CARIM), Maastricht, The Netherlands
| | - Elien B Engels
- Department of Physiology, Maastricht University, Cardiovascular Research Institute Maastricht (CARIM), Maastricht, The Netherlands
| | - Yuri Blaauw
- Department of Cardiology, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Justin G L M Luermans
- Department of Cardiology, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Laurent Pison
- Department of Cardiology, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Harry J Crijns
- Department of Cardiology, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Frits W Prinzen
- Department of Physiology, Maastricht University, Cardiovascular Research Institute Maastricht (CARIM), Maastricht, The Netherlands
| | - Kevin Vernooy
- Department of Cardiology, Maastricht University Medical Center, Maastricht, The Netherlands,.
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Almer J, Zusterzeel R, Strauss DG, Trägårdh E, Maynard C, Wagner GS, Engblom H. Prevalence of manual Strauss LBBB criteria in patients diagnosed with the automated Glasgow LBBB criteria. J Electrocardiol 2015; 48:558-64. [DOI: 10.1016/j.jelectrocard.2015.01.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Indexed: 01/23/2023]
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Zhang ZM, Rautaharju PM, Prineas RJ, Whitsel EA, Tereshchenko L, Soliman EZ. A wide QRS/T angle in bundle branch blocks is associated with increased risk for coronary heart disease and all-cause mortality in the Atherosclerosis Risk in Communities (ARIC) Study. J Electrocardiol 2015; 48:672-7. [PMID: 25959262 DOI: 10.1016/j.jelectrocard.2015.04.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Indexed: 10/23/2022]
Abstract
BACKGROUND Repolarization abnormality in bundle branch blocks (BBB) is traditionally ignored. This study evaluated the prognostic value of QRS/T angle for mortality in the presence and absence of BBB. METHODS AND RESULTS Total 15,408 participants (mean age 54 years, 55.2% women, 26.9% blacks, 2.8% with BBB) were from the Arteriosclerosis Risk in Communities Study. Sex stratified Cox regression models were used to compute hazard ratios (HRs) with 95% confidence intervals (CIs) for coronary heart disease (CHD) and all-cause mortality for wide spatial QRS/T angle with and without BBB including right BBB (RBBB), left BBB (LBBB) and indetermined-type ventricular conduction defect (IVCD) and RBBB combined with left anterior fascicular block. During a median 22-year follow-up, 4767 deaths occurred, 728 of them CHD deaths. Using the No-BBB with QRS/T angle below median value as gender-specific reference groups, the mortality risk increase was significant for both women and men with No-BBB and QRS/T angle above the median value. In the pooled ICVD/LBBB group, the risk for CHD death was increased 15.9-fold in women and 6.04 fold in men, and for all-cause deaths 3.01-fold in women and 1.84-fold in men. However, the mortality risk in isolated RBBB group was only significantly increased in women but not in men. CONCLUSION A wide spatial QRS/T angle in BBB is associated with increased risk for CHD and all-cause mortality over and above the predictive value for BBB alone. The risk for women is as high as or higher than that in men.
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Affiliation(s)
- Zhu-Ming Zhang
- Epidemiological Cardiology Research Center (EPICARE), Department of Epidemiology and Prevention, Division of Public Health Sciences, Wake Forest School of Medicine, Winston-Salem, North Carolina.
| | - Pentti M Rautaharju
- Epidemiological Cardiology Research Center (EPICARE), Department of Epidemiology and Prevention, Division of Public Health Sciences, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Ronald J Prineas
- Epidemiological Cardiology Research Center (EPICARE), Department of Epidemiology and Prevention, Division of Public Health Sciences, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Eric A Whitsel
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Larisa Tereshchenko
- Knight Cardiovascular Institute, Oregon Health & Science University, Portland, Oregon
| | - Elsayed Z Soliman
- Epidemiological Cardiology Research Center (EPICARE), Department of Epidemiology and Prevention, Division of Public Health Sciences, Wake Forest School of Medicine, Winston-Salem, North Carolina; Department of Internal Medicine, Section of Cardiology, Wake Forest School of Medicine, Winston-Salem, North Carolina
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Xia X, Wieslander B, Strauss DG, Wagner GS, Zareba W, Moss AJ, Couderc JP. Automatic QRS Selvester scoring system in patients with left bundle branch block. Europace 2015; 18:308-14. [DOI: 10.1093/europace/euv040] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 01/25/2015] [Indexed: 11/14/2022] Open
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van Deursen CJ, Vernooy K, Dudink E, Bergfeldt L, Crijns HJ, Prinzen FW, Wecke L. Vectorcardiographic QRS area as a novel predictor of response to cardiac resynchronization therapy. J Electrocardiol 2015; 48:45-52. [DOI: 10.1016/j.jelectrocard.2014.10.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2014] [Indexed: 12/17/2022]
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Sundh F, Ugander M. Impact of left bundle branch block after transcatheter aortic valve replacement. J Electrocardiol 2014; 47:608-11. [DOI: 10.1016/j.jelectrocard.2014.07.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Indexed: 01/07/2023]
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Transcatheter aortic valve implantation-induced left bundle branch block: causes and consequences. J Cardiovasc Transl Res 2014; 7:395-405. [PMID: 24800873 DOI: 10.1007/s12265-014-9560-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 03/21/2014] [Indexed: 10/25/2022]
Abstract
Transcatheter aortic valve implantation (TAVI) is an alternative treatment option for patients with severe aortic valve stenosis who do not qualify for surgical aortic valve replacement (AVR). Besides its proven clinical benefits, one of the complications of TAVI is the creation of conduction abnormalities, like left bundle branch block (LBBB). New LBBB occurs between 7 and 65% of cases, numbers that differ considerably between devices. In this review, we discuss the possible causes and the clinical significance of TAVI-induced LBBB. Several device- and procedural-related factors seem responsible for the development of LBBB, of which depth of implantation and balloon-annulus diameter ratio are the most important ones. TAVI-induced LBBB negatively affects cardiac function and hospitalization, but its impact on mortality is subject of debate. Future research and registries should implement strict diagnostic criteria for LBBB together with recording of its timing and persistence.
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Cardiovascular magnetic resonance imaging in asymptomatic patients with connective tissue disease and recent onset left bundle branch block. Int J Cardiol 2014; 171:82-7. [DOI: 10.1016/j.ijcard.2013.11.059] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 11/23/2013] [Indexed: 01/24/2023]
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Galeotti L, van Dam PM, Loring Z, Chan D, Strauss DG. Evaluating strict and conventional left bundle branch block criteria using electrocardiographic simulations. Europace 2013; 15:1816-21. [DOI: 10.1093/europace/eut132] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Differentiation between left bundle branch block and left ventricular hypertrophy: Implications for cardiac resynchronization therapy. J Electrocardiol 2012; 45:635-9. [DOI: 10.1016/j.jelectrocard.2012.09.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Indexed: 11/21/2022]
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Bacharova L, Szathmary V, Potse M, Mateasik A. Computer simulation of ECG manifestations of left ventricular electrical remodeling. J Electrocardiol 2012; 45:630-4. [PMID: 22960164 DOI: 10.1016/j.jelectrocard.2012.07.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Indexed: 10/27/2022]
Abstract
An increased QRS voltage is considered to be specific for the electrocardiogram (ECG) diagnosis of left ventricular hypertrophy (LVH). However, the QRS-complex patterns in patients with LVH cover a broader spectrum: increased QRS voltage, prolonged QRS duration, left axis deviation, and left anterior fascicular block- and left bundle branch block-like patterns, as well as pseudo-normal QRS patterns. The classical interpretation of the QRS patterns in LVH relates these changes to increased left ventricular mass (LVM) per se, while tending to neglect the modified active and passive electrical properties of the myocardium. However, it has been well documented that both active and passive electrical properties in LVH are altered. Using computer simulations, we have shown that an increased LVM is not the only determinant of QRS complex changes in LVH, as these changes could also be produced without changing the left ventricular mass, implying that these QRS patterns can be present in patients before their LVM exceeds the arbitrary upper normal limits. Our results link the experimental evidence on electrical remodeling with clinical interpretation of ECG changes in patients with LVH and stress the necessity of a complex interpretation of the QRS patterns considering both spatial and nonspatial determinants in terms of the spatial angle theory. We assume that hypertrophic electrical remodeling in combination with changes in left ventricular size and shape explains the variety of ECG patterns as well as the discrepancies between ECG and left ventricular mass.
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Rodriguez-Padial L, Bacharova L. Electrical remodeling in left ventricular hypertrophy—is there a unifying hypothesis for the variety of electrocardiographic criteria for the diagnosis of left ventricular hypertrophy? J Electrocardiol 2012; 45:494-7. [DOI: 10.1016/j.jelectrocard.2012.06.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Indexed: 10/28/2022]
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Perrin MJ, Green MS, Redpath CJ, Nery PB, Keren A, Beanlands RS, Birnie DH. Greater response to cardiac resynchronization therapy in patients with true complete left bundle branch block: a PREDICT substudy. Europace 2011; 14:690-5. [DOI: 10.1093/europace/eur381] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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