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Hnatkova K, Andršová I, Novotný T, Vanderberk B, Sprenkeler D, Junttila J, Reichlin T, Schlögl S, Vos MA, Friede T, Bauer A, Huikuri HV, Willems R, Schmidt G, Sticherling C, Zabel M, Malik M. QRS complex and T wave planarity for the efficacy prediction of automatic implantable defibrillators. Heart 2024; 110:178-187. [PMID: 37714697 PMCID: PMC10850677 DOI: 10.1136/heartjnl-2023-322878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 08/19/2023] [Indexed: 09/17/2023] Open
Abstract
OBJECTIVE To test the hypothesis that in recipients of primary prophylactic implantable cardioverter-defibrillators (ICDs), the non-planarity of ECG vector loops predicts (a) deaths despite ICD protection and (b) appropriate ICD shocks. METHODS Digital pre-implant ECGs were collected in 1948 ICD recipients: 21.4% females, median age 65 years, 61.5% ischaemic heart disease (IHD). QRS and T wave three-dimensional loops were constructed using singular value decomposition that allowed to measure the vector loop planarity. The non-planarity, that is, the twist of the three-dimensional loops out of a single plane, was related to all-cause mortality (n=294; 15.3% females; 68.7% IHD) and appropriate ICD shocks (n=162; 10.5% females; 87.7% IHD) during 5-year follow-up after device implantation. Using multivariable Cox regression, the predictive power of QRS and T wave non-planarity was compared with that of age, heart rate, left ventricular ejection fraction, QRS duration, spatial QRS-T angle, QTc interval and T-peak to T-end interval. RESULTS QRS non-planarity was significantly (p<0.001) associated with follow-up deaths despite ICD protection with HR of 1.339 (95% CI 1.165 to 1.540) but was only univariably associated with appropriate ICD shocks. Non-planarity of the T wave loop was the only ECG-derived index significantly (p<0.001) associated with appropriate ICD shocks with multivariable Cox regression HR of 1.364 (1.180 to 1.576) but was not associated with follow-up mortality. CONCLUSIONS The analysed data suggest that QRS and T wave non-planarity might offer distinction between patients who are at greater risk of death despite ICD protection and those who are likely to use the defibrillator protection.
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Affiliation(s)
- Katerina Hnatkova
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Irena Andršová
- Department of Internal Medicine and Cardiology, University Hospital Brno, Brno, Czech Republic
- Department of Internal Medicine and Cardiology, Masaryk University, Brno, Czech Republic
| | - Tomáš Novotný
- Department of Internal Medicine and Cardiology, University Hospital Brno, Brno, Czech Republic
- Department of Internal Medicine and Cardiology, Masaryk University, Brno, Czech Republic
| | - Bert Vanderberk
- Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium
| | - David Sprenkeler
- Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Juhani Junttila
- MRC Oulu, University Central Hospital of Oulu and University of Oulu, Oulu, Finland
| | - Tobias Reichlin
- Department of Cardiology, Inselspital, Bern University Hospital, Bern, Switzerland
| | - Simon Schlögl
- Department of Cardiology and Pneumology, University Medical Center Göttingen, Gottingen, Germany
- German Center of Cardiovascular Research (DZHK), partner site Göttingen, Göttingen, Germany
| | - Marc A Vos
- Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Tim Friede
- German Center of Cardiovascular Research (DZHK), partner site Göttingen, Göttingen, Germany
- Department of Medical Statistics, University Medical Center Göttingen, Göttingen, Germany
| | - Axel Bauer
- University Hospital for Internal Medicine III, Medical University Innsbruck, Innsbruck, Austria
| | - Heikki V Huikuri
- University Central Hospital of Oulu and University of Oulu, Oulu, Finland
| | - Rik Willems
- Division of Experimental Cardiology, Department of Cardiovascular Diseases, University of Leuven, Leuven, Belgium
- Division of Clinical Cardiology, University Hospitals Leuven, Leuven, Belgium
| | - Georg Schmidt
- Medizinische Klinik, Klinikum rechts der Isar der Technischen Universität München, Munich, Germany
| | | | - Markus Zabel
- German Center of Cardiovascular Research (DZHK), partner site Göttingen, Göttingen, Germany
- Cardiology and Pneumology, Heart Center, University Hospital Göttingen, Göttingen, Germany
| | - Marek Malik
- National Heart and Lung Institute, Imperial College London, London, UK
- Department of Internal Medicine and Cardiology, University Hospital Brno, Brno, Czech Republic
- Department of Internal Medicine and Cardiology, Masaryk University, Brno, Czech Republic
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Hnatkova K, Andršová I, Novotný T, Britton A, Shipley M, Vandenberk B, Sprenkeler DJ, Junttila J, Reichlin T, Schlögl S, Vos MA, Friede T, Bauer A, Huikuri HV, Willems R, Schmidt G, Franz MR, Sticherling C, Zabel M, Malik M. QRS micro-fragmentation as a mortality predictor. Eur Heart J 2022; 43:4177-4191. [PMID: 35187560 PMCID: PMC9584751 DOI: 10.1093/eurheartj/ehac085] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 01/05/2022] [Accepted: 02/08/2022] [Indexed: 11/12/2022] Open
Abstract
AIMS Fragmented QRS complex with visible notching on standard 12-lead electrocardiogram (ECG) is understood to represent depolarization abnormalities and to signify risk of cardiac events. Depolarization abnormalities with similar prognostic implications likely exist beyond visual recognition but no technology is presently suitable for quantification of such invisible ECG abnormalities. We present such a technology. METHODS AND RESULTS A signal processing method projects all ECG leads of the QRS complex into optimized three perpendicular dimensions, reconstructs the ECG back from this three-dimensional projection, and quantifies the difference (QRS 'micro'-fragmentation, QRS-μf) between the original and reconstructed signals. QRS 'micro'-fragmentation was assessed in three different populations: cardiac patients with automatic implantable cardioverter-defibrillators, cardiac patients with severe abnormalities, and general public. The predictive value of QRS-μf for mortality was investigated both univariably and in multivariable comparisons with other risk factors including visible QRS 'macro'-fragmentation, QRS-Mf. The analysis was made in a total of 7779 subjects of whom 504 have not survived the first 5 years of follow-up. In all three populations, QRS-μf was strongly predictive of survival (P < 0.001 univariably, and P < 0.001 to P = 0.024 in multivariable regression analyses). A similar strong association with outcome was found when dichotomizing QRS-μf prospectively at 3.5%. When QRS-μf was used in multivariable analyses, QRS-Mf and QRS duration lost their predictive value. CONCLUSION In three populations with different clinical characteristics, QRS-μf was a powerful mortality risk factor independent of several previously established risk indices. Electrophysiologic abnormalities that contribute to increased QRS-μf values are likely responsible for the predictive power of visible QRS-Mf.
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Affiliation(s)
- Katerina Hnatkova
- National Heart and Lung Institute, Imperial College, ICTEM, Hammersmith Campus, 72 Du Cane Road, Shepherd's Bush, London W12 0NN, UK
| | - Irena Andršová
- Department of Internal Medicine and Cardiology, University Hospital Brno, Brno, Czech Republic.,Department of Internal Medicine and Cardiology, Masaryk University, Brno, Czech Republic
| | - Tomáš Novotný
- Department of Internal Medicine and Cardiology, University Hospital Brno, Brno, Czech Republic.,Department of Internal Medicine and Cardiology, Masaryk University, Brno, Czech Republic
| | - Annie Britton
- Research Department of Epidemiology and Public Health, University College London, UK
| | - Martin Shipley
- Research Department of Epidemiology and Public Health, University College London, UK
| | - Bert Vandenberk
- Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium
| | - David J Sprenkeler
- Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Juhani Junttila
- Medical Research Center Oulu, University Central Hospital of Oulu and University of Oulu, Oulu, Finland
| | - Tobias Reichlin
- Department of Cardiology, Inselspital, Bern University Hospital, Bern, Switzerland
| | - Simon Schlögl
- Department of Cardiology and Pneumology, University Medical Center, Göttingen, Germany.,German Center of Cardiovascular Research (DZHK), Partner Site Göttingen, Göttingen, Germany
| | - Marc A Vos
- Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Tim Friede
- German Center of Cardiovascular Research (DZHK), Partner Site Göttingen, Göttingen, Germany.,Department of Medical Statistics, University Medical Center Göttingen, Göttingen, Germany
| | - Axel Bauer
- University Hospital for Internal Medicine III, Medical University Innsbruck, Innsbruck, Austria
| | - Heikki V Huikuri
- Medical Research Center Oulu, University Central Hospital of Oulu and University of Oulu, Oulu, Finland
| | - Rik Willems
- Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium
| | - Georg Schmidt
- Klinikum rechts der Isar, Technical University of Munich, Munich, Germany.,German Center for Cardiovascular Research Partner Site Munich Heart Alliance, Munich, Germany
| | - Michael R Franz
- Veteran Affairs and Georgetown University Medical Centers, Washington, DC, USA
| | | | - Markus Zabel
- Department of Cardiology and Pneumology, University Medical Center, Göttingen, Germany.,German Center of Cardiovascular Research (DZHK), Partner Site Göttingen, Göttingen, Germany
| | - Marek Malik
- National Heart and Lung Institute, Imperial College, ICTEM, Hammersmith Campus, 72 Du Cane Road, Shepherd's Bush, London W12 0NN, UK.,Department of Internal Medicine and Cardiology, Masaryk University, Brno, Czech Republic
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Andršová I, Hnatkova K, Toman O, Šišáková M, Smetana P, Huster KM, Barthel P, Novotný T, Schmidt G, Malik M. Intra-subject stability of different expressions of spatial QRS-T angle and their relationship to heart rate. Front Physiol 2022; 13:939633. [DOI: 10.3389/fphys.2022.939633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 07/18/2022] [Indexed: 11/13/2022] Open
Abstract
Three-dimensional angle between the QRS complex and T wave vectors is a known powerful cardiovascular risk predictor. Nevertheless, several physiological properties of the angle are unknown or poorly understood. These include, among others, intra-subject profiles and stability of the angle relationship to heart rate, characteristics of angle/heart-rate hysteresis, and the changes of these characteristics with different modes of QRS-T angle calculation. These characteristics were investigated in long-term 12-lead Holter recordings of 523 healthy volunteers (259 females). Three different algorithmic methods for the angle computation were based on maximal vector magnitude of QRS and T wave loops, areas under the QRS complex and T wave curvatures in orthogonal leads, and weighted integration of all QRS and T wave vectors moving around the respective 3-dimensional loops. These methods were applied to orthogonal leads derived either by a uniform conversion matrix or by singular value decomposition (SVD) of the original 12-lead ECG, giving 6 possible ways of expressing the angle. Heart rate hysteresis was assessed using the exponential decay models. All these methods were used to measure the angle in 659,313 representative waveforms of individual 10-s ECG samples and in 7,350,733 individual beats contained in the same 10-s samples. With all measurement methods, the measured angles fitted second-degree polynomial regressions to the underlying heart rate. Independent of the measurement method, the angles were found significantly narrower in females (p < 0.00001) with the differences to males between 10o and 20o, suggesting that in future risk-assessment studies, different angle dichotomies are needed for both sexes. The integrative method combined with SVD leads showed the highest intra-subject reproducibility (p < 0.00001). No reproducible delay between heart rate changes and QRS-T angle changes was found. This was interpreted as a suggestion that the measurement of QRS-T angle might offer direct assessment of cardiac autonomic responsiveness at the ventricular level.
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Toman O, Hnatkova K, Šišáková M, Smetana P, Huster KM, Barthel P, Novotný T, Andršová I, Schmidt G, Malik M. Short-Term Beat-to-Beat QT Variability Appears Influenced More Strongly by Recording Quality Than by Beat-to-Beat RR Variability. Front Physiol 2022; 13:863873. [PMID: 35431991 PMCID: PMC9011003 DOI: 10.3389/fphys.2022.863873] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 02/28/2022] [Indexed: 12/14/2022] Open
Abstract
Increases in beat-to-beat variability of electrocardiographic QT interval duration have repeatedly been associated with increased risk of cardiovascular events and complications. The measurements of QT variability are frequently normalized for the underlying RR interval variability. Such normalization supports the concept of the so-called immediate RR effect which relates each QT interval to the preceding RR interval. The validity of this concept was investigated in the present study together with the analysis of the influence of electrocardiographic morphological stability on QT variability measurements. The analyses involved QT and RR measurements in 6,114,562 individual beats of 642,708 separate 10-s ECG samples recorded in 523 healthy volunteers (259 females). Only beats with high morphology correlation (r > 0.99) with representative waveforms of the 10-s ECG samples were analyzed, assuring that only good quality recordings were included. In addition to these high correlations, SDs of the ECG signal difference between representative waveforms and individual beats expressed morphological instability and ECG noise. In the intra-subject analyses of both individual beats and of 10-s averages, QT interval variability was substantially more strongly related to the ECG noise than to the underlying RR variability. In approximately one-third of the analyzed ECG beats, the prolongation or shortening of the preceding RR interval was followed by the opposite change of the QT interval. In linear regression analyses, underlying RR variability within each 10-s ECG sample explained only 5.7 and 11.1% of QT interval variability in females and males, respectively. On the contrary, the underlying ECG noise contents of the 10-s samples explained 56.5 and 60.1% of the QT interval variability in females and males, respectively. The study concludes that the concept of stable and uniform immediate RR interval effect on the duration of subsequent QT interval duration is highly questionable. Even if only stable beat-to-beat measurements of QT interval are used, the QT interval variability is still substantially influenced by morphological variability and noise pollution of the source ECG recordings. Even when good quality recordings are used, noise contents of the electrocardiograms should be objectively examined in future studies of QT interval variability.
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Affiliation(s)
- Ondřej Toman
- Department of Internal Medicine and Cardiology, University Hospital Brno, Brno, Czechia
- Department of Internal Medicine and Cardiology, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Katerina Hnatkova
- National Heart and Lung Institute, Imperial College, London, United Kingdom
| | - Martina Šišáková
- Department of Internal Medicine and Cardiology, University Hospital Brno, Brno, Czechia
- Department of Internal Medicine and Cardiology, Faculty of Medicine, Masaryk University, Brno, Czechia
| | | | | | - Petra Barthel
- Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Tomáš Novotný
- Department of Internal Medicine and Cardiology, University Hospital Brno, Brno, Czechia
- Department of Internal Medicine and Cardiology, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Irena Andršová
- Department of Internal Medicine and Cardiology, University Hospital Brno, Brno, Czechia
- Department of Internal Medicine and Cardiology, Faculty of Medicine, Masaryk University, Brno, Czechia
- *Correspondence: Irena Andršová
| | - Georg Schmidt
- Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Marek Malik
- Department of Internal Medicine and Cardiology, Faculty of Medicine, Masaryk University, Brno, Czechia
- National Heart and Lung Institute, Imperial College, London, United Kingdom
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Andršová I, Hnatkova K, Šišáková M, Toman O, Smetana P, Huster KM, Barthel P, Novotný T, Schmidt G, Malik M. Sex and Rate Change Differences in QT/RR Hysteresis in Healthy Subjects. Front Physiol 2022; 12:814542. [PMID: 35197861 PMCID: PMC8859307 DOI: 10.3389/fphys.2021.814542] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Accepted: 12/15/2021] [Indexed: 11/13/2022] Open
Abstract
While it is now well-understood that the extent of QT interval changes due to underlying heart rate differences (i.e., the QT/RR adaptation) needs to be distinguished from the speed with which the QT interval reacts to heart rate changes (i.e., the so-called QT/RR hysteresis), gaps still exist in the physiologic understanding of QT/RR hysteresis processes. This study was designed to address the questions of whether the speed of QT adaptation to heart rate changes is driven by time or by number of cardiac cycles; whether QT interval adaptation speed is the same when heart rate accelerates and decelerates; and whether the characteristics of QT/RR hysteresis are related to age and sex. The study evaluated 897,570 measurements of QT intervals together with their 5-min histories of preceding RR intervals, all recorded in 751 healthy volunteers (336 females) aged 34.3 ± 9.5 years. Three different QT/RR adaptation models were combined with exponential decay models that distinguished time-based and interval-based QT/RR hysteresis. In each subject and for each modelling combination, a best-fit combination of modelling parameters was obtained by seeking minimal regression residuals. The results showed that the response of QT/RR hysteresis appears to be driven by absolute time rather than by the number of cardiac cycles. The speed of QT/RR hysteresis was found decreasing with increasing age whilst the duration of individually rate corrected QTc interval was found increasing with increasing age. Contrary to the longer QTc intervals, QT/RR hysteresis speed was faster in females. QT/RR hysteresis differences between heart rate acceleration and deceleration were not found to be physiologically systematic (i.e., they differed among different healthy subjects), but on average, QT/RR hysteresis speed was found slower after heart rate acceleration than after rate deceleration.
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Affiliation(s)
- Irena Andršová
- Faculty of Medicine, Department of Internal Medicine and Cardiology, University Hospital Brno, Masaryk University, Brno, Czechia
| | - Katerina Hnatkova
- National Heart and Lung Institute, Imperial College, London, United Kingdom
| | - Martina Šišáková
- Faculty of Medicine, Department of Internal Medicine and Cardiology, University Hospital Brno, Masaryk University, Brno, Czechia
| | - Ondřej Toman
- Faculty of Medicine, Department of Internal Medicine and Cardiology, University Hospital Brno, Masaryk University, Brno, Czechia
| | | | - Katharina M Huster
- Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Petra Barthel
- Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Tomáš Novotný
- Faculty of Medicine, Department of Internal Medicine and Cardiology, University Hospital Brno, Masaryk University, Brno, Czechia
| | - Georg Schmidt
- Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Marek Malik
- National Heart and Lung Institute, Imperial College, London, United Kingdom.,Faculty of Medicine, Department of Internal Medicine and Cardiology, Masaryk University, Brno, Czechia
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Andršová I, Hnatkova K, Šišáková M, Toman O, Smetana P, Huster KM, Barthel P, Novotný T, Schmidt G, Malik M. Influence of heart rate correction formulas on QTc interval stability. Sci Rep 2021; 11:14269. [PMID: 34253795 PMCID: PMC8275798 DOI: 10.1038/s41598-021-93774-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 06/30/2021] [Indexed: 12/12/2022] Open
Abstract
Monitoring of QTc interval is mandated in different clinical conditions. Nevertheless, intra-subject variability of QTc intervals reduces the clinical utility of QTc monitoring strategies. Since this variability is partly related to QT heart rate correction, 10 different heart rate corrections (Bazett, Fridericia, Dmitrienko, Framingham, Schlamowitz, Hodges, Ashman, Rautaharju, Sarma, and Rabkin) were applied to 452,440 ECG measurements made in 539 healthy volunteers (259 females, mean age 33.3 ± 8.4 years). For each correction formula, the short term (5-min time-points) and long-term (day-time hours) variability of rate corrected QT values (QTc) was investigated together with the comparisons of the QTc values with individually corrected QTcI values obtained by subject-specific modelling of the QT/RR relationship and hysteresis. The results showed that (a) both in terms of short-term and long-term QTc variability, Bazett correction led to QTc values that were more variable than the results of other corrections (p < 0.00001 for all), (b) the QTc variability by Fridericia and Framingham corrections were not systematically different from each other but were lower than the results of other corrections (p-value between 0.033 and < 0.00001), and (c) on average, Bazett QTc values departed from QTcI intervals more than the QTc values of other corrections. The study concludes that (a) previous suggestions that Bazett correction should no longer be used in clinical practice are fully justified, (b) replacing Bazett correction with Fridericia and/or Framingham corrections would improve clinical QTc monitoring, (c) heart rate stability is needed for valid QTc assessment, and (d) development of further QTc corrections for day-to-day use is not warranted.
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Affiliation(s)
- Irena Andršová
- Department of Internal Medicine and Cardiology, Faculty of Medicine, University Hospital Brno, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
| | - Katerina Hnatkova
- National Heart and Lung Institute, Imperial College, ICTEM, Hammersmith Campus, 72 Du Cane Rd, Shepherd's Bush, London, W12 0NN, England, UK
| | - Martina Šišáková
- Department of Internal Medicine and Cardiology, Faculty of Medicine, University Hospital Brno, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
| | - Ondřej Toman
- Department of Internal Medicine and Cardiology, Faculty of Medicine, University Hospital Brno, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
| | - Peter Smetana
- Wilhelminenspital der Stadt Wien, Montleartstraße 37, 1160, Vienna, Austria
| | - Katharina M Huster
- Klinikum rechts der Isar, Technische Universität München, Ismaninger Straße 22, 81675, Munich, Germany
| | - Petra Barthel
- Klinikum rechts der Isar, Technische Universität München, Ismaninger Straße 22, 81675, Munich, Germany
| | - Tomáš Novotný
- Department of Internal Medicine and Cardiology, Faculty of Medicine, University Hospital Brno, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
| | - Georg Schmidt
- Klinikum rechts der Isar, Technische Universität München, Ismaninger Straße 22, 81675, Munich, Germany
| | - Marek Malik
- National Heart and Lung Institute, Imperial College, ICTEM, Hammersmith Campus, 72 Du Cane Rd, Shepherd's Bush, London, W12 0NN, England, UK. .,Department of Internal Medicine and Cardiology, Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic.
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Synková I, Bébarová M, Andršová I, Chmelikova L, Švecová O, Hošek J, Pásek M, Vít P, Valášková I, Gaillyová R, Navrátil R, Novotný T. Long-QT founder variant T309I-Kv7.1 with dominant negative pattern may predispose delayed afterdepolarizations under β-adrenergic stimulation. Sci Rep 2021; 11:3573. [PMID: 33574382 PMCID: PMC7878757 DOI: 10.1038/s41598-021-81670-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 12/30/2020] [Indexed: 11/30/2022] Open
Abstract
The variant c.926C > T (p.T309I) in KCNQ1 gene was identified in 10 putatively unrelated Czech families with long QT syndrome (LQTS). Mutation carriers (24 heterozygous individuals) were more symptomatic compared to their non-affected relatives (17 individuals). The carriers showed a mild LQTS phenotype including a longer QTc interval at rest (466 ± 24 ms vs. 418 ± 20 ms) and after exercise (508 ± 32 ms vs. 417 ± 24 ms), 4 syncopes and 2 aborted cardiac arrests. The same haplotype associated with the c.926C > T variant was identified in all probands. Using the whole cell patch clamp technique and confocal microscopy, a complete loss of channel function was revealed in the homozygous setting, caused by an impaired channel trafficking. Dominant negativity with preserved reactivity to β-adrenergic stimulation was apparent in the heterozygous setting. In simulations on a human ventricular cell model, the dysfunction resulted in delayed afterdepolarizations (DADs) and premature action potentials under β-adrenergic stimulation that could be prevented by a slight inhibition of calcium current. We conclude that the KCNQ1 variant c.926C > T is the first identified LQTS-related founder mutation in Central Europe. The dominant negative channel dysfunction may lead to DADs under β-adrenergic stimulation. Inhibition of calcium current could be possible therapeutic strategy in LQTS1 patients refractory to β-blocker therapy.
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Affiliation(s)
- Iva Synková
- Department of Medical Genetics, University Hospital Brno and Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic.,Department of Experimental Biology, Faculty of Science, Masaryk University, Kotlářská 267/2, 611 37, Brno, Czech Republic
| | - Markéta Bébarová
- Department of Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.
| | - Irena Andršová
- Department of Internal Medicine and Cardiology, University Hospital Brno and Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
| | - Larisa Chmelikova
- Department of Biomedical Engineering, Faculty of Electrical Engineering and Communication, Brno University of Technology, Technická 10, 616 00, Brno, Czech Republic
| | - Olga Švecová
- Department of Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Jan Hošek
- Division of Biologically Active Complexes and Molecular Magnets, Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacký University in Olomouc, Šlechtitelů 27, 783 71, Olomouc, Czech Republic
| | - Michal Pásek
- Department of Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.,Institute of Thermomechanics, Czech Academy of Sciences, Dolejškova 5, 182 00, Prague, Czech Republic
| | - Pavel Vít
- Department of Paediatrics, University Hospital Brno and Faculty of Medicine, Masaryk University, Černopolní 9, 613 00, Brno, Czech Republic
| | - Iveta Valášková
- Department of Medical Genetics, University Hospital Brno and Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
| | - Renata Gaillyová
- Department of Medical Genetics, University Hospital Brno and Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
| | - Rostislav Navrátil
- Repromeda, Clinic for Reproductive Medicine and Preimplantation Genetic Diagnosis, Biology Park, Studentská 812/6, 625 00, Brno, Czech Republic
| | - Tomáš Novotný
- Department of Internal Medicine and Cardiology, University Hospital Brno and Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
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Andršová I, Hnatkova K, Šišáková M, Toman O, Smetana P, Huster KM, Barthel P, Novotný T, Schmidt G, Malik M. Heart Rate Dependency and Inter-Lead Variability of the T Peak - T End Intervals. Front Physiol 2021; 11:595815. [PMID: 33384609 PMCID: PMC7769826 DOI: 10.3389/fphys.2020.595815] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 10/14/2020] [Indexed: 11/24/2022] Open
Abstract
The electrocardiographic (ECG) assessment of the T peak–T end (Tpe) intervals has been used in many clinical studies, but several related physiological aspects have not been reported. Specifically, the sources of the Tpe differences between different ECG leads have not been systematically researched, the relationship of Tpe duration to underlying heart rate has not been firmly established, and little is known about the mutual correspondence of Tpe intervals measured in different ECG leads. This study evaluated 796,620 10-s 12-lead ECGs obtained from long-term Holters recorded in 639 healthy subjects (311 female) aged 33.8 ± 9.4 years. For each ECG, transformation to orthogonal XYZ lead was used to measure Tpe in the orthogonal vector magnitude (used as a reference for lead-to-lead comparisons) and to construct a three-dimensional T wave loop. The loop roundness was expressed by a ratio between its circumference and length. These ratios were significantly related to the standard deviation of Tpe durations in different ECG leads. At the underlying heart rate of 60 beats per minute, Tpe intervals were shorter in female than in male individuals (82.5 ± 5.6 vs 90.0 ± 6.5 ms, p < 0.0001). When studying linear slopes between Tpe intervals measured in different leads and the underlying heart rate, we found only minimal heart rate dependency, which was not systematic across the ECG leads and/or across the population. For any ECG lead, positive Tpe/RR slope was found in some subjects (e.g., 79 and 25% of subjects for V2 and V4 measurements, respectively) and a negative Tpe/RR slope in other subjects (e.g., 40 and 65% for V6 and V5, respectively). The steepest positive and negative Tpe/RR slopes were found for measurements in lead V2 and V4, respectively. In all leads, the Tpe/RR slope values were close to zero, indicating, on average, Tpe changes well below 2 ms for RR interval changes of 100 ms. On average, longest Tpe intervals were measured in lead V2, the shortest in lead III. The study concludes that the Tpe intervals measured in different leads cannot be combined. Irrespective of the measured ECG lead, the Tpe interval is not systematically heart rate dependent, and no heart rate correction should be used in clinical Tpe investigations.
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Affiliation(s)
- Irena Andršová
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Katerina Hnatkova
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Martina Šišáková
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Ondřej Toman
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Brno, Czechia
| | | | - Katharina M Huster
- Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Petra Barthel
- Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Tomáš Novotný
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Georg Schmidt
- Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Marek Malik
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
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Andršová I, Hnatkova K, Šišáková M, Toman O, Smetana P, Huster KM, Barthel P, Novotný T, Schmidt G, Malik M. Heart Rate Influence on the QT Variability Risk Factors. Diagnostics (Basel) 2020; 10:diagnostics10121096. [PMID: 33339231 PMCID: PMC7767205 DOI: 10.3390/diagnostics10121096] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 12/05/2020] [Accepted: 12/14/2020] [Indexed: 12/14/2022] Open
Abstract
QT interval variability, mostly expressed by QT variability index (QTVi), has repeatedly been used in risk diagnostics. Physiologic correlates of QT variability expressions have been little researched especially when measured in short 10-second electrocardiograms (ECGs). This study investigated different QT variability indices, including QTVi and the standard deviation of QT interval durations (SDQT) in 657,287 10-second ECGs recorded in 523 healthy subjects (259 females). The indices were related to the underlying heart rate and to the 10-second standard deviation of RR intervals (SDRR). The analyses showed that both QTVi and SDQT (as well as other QT variability indices) were highly statistically significantly (p < 0.00001) influenced by heart rate and that QTVi showed poor intra-subject reproducibility (coefficient of variance approaching 200%). Furthermore, sequential analysis of regression variance showed that SDQT was more strongly related to the underlying heart rate than to SDRR, and that QTVi was influenced by the underlying heart rate and SDRR more strongly than by SDQT (p < 0.00001 for these comparisons of regression dependency). The study concludes that instead of QTVi, simpler expressions of QT interval variability, such as SDQT, appear preferable for future applications especially if multivariable combination with the underlying heart rate is used.
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Affiliation(s)
- Irena Andršová
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00 Brno, Czech Republic; (I.A.); (M.Š.); (O.T.); (T.N.)
| | - Katerina Hnatkova
- National Heart and Lung Institute, Imperial College, 72 Du Cane Road, Shepherd’s Bush, London W12 0NN, UK;
| | - Martina Šišáková
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00 Brno, Czech Republic; (I.A.); (M.Š.); (O.T.); (T.N.)
| | - Ondřej Toman
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00 Brno, Czech Republic; (I.A.); (M.Š.); (O.T.); (T.N.)
| | - Peter Smetana
- Wilhelminenspital der Stadt Wien, Montleartstraße 37, 1160 Vienna, Austria;
| | - Katharina M. Huster
- Klinikum rechts der Isar, Technische Universität München, Ismaninger Straße 22, D-81675 Munich, Germany; (K.M.H.); (P.B.); (G.S.)
| | - Petra Barthel
- Klinikum rechts der Isar, Technische Universität München, Ismaninger Straße 22, D-81675 Munich, Germany; (K.M.H.); (P.B.); (G.S.)
| | - Tomáš Novotný
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00 Brno, Czech Republic; (I.A.); (M.Š.); (O.T.); (T.N.)
| | - Georg Schmidt
- Klinikum rechts der Isar, Technische Universität München, Ismaninger Straße 22, D-81675 Munich, Germany; (K.M.H.); (P.B.); (G.S.)
| | - Marek Malik
- National Heart and Lung Institute, Imperial College, 72 Du Cane Road, Shepherd’s Bush, London W12 0NN, UK;
- Department of Internal Medicine and Cardiology, Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00 Brno, Czech Republic
- Correspondence:
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Andršová I, Hnatkova K, Helánová K, Šišáková M, Novotný T, Kala P, Malik M. Problems with Bazett QTc correction in paediatric screening of prolonged QTc interval. BMC Pediatr 2020; 20:558. [PMID: 33317470 PMCID: PMC7734859 DOI: 10.1186/s12887-020-02460-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 12/08/2020] [Indexed: 02/06/2023] Open
Abstract
Background Bazett formula is frequently used in paediatric screening for the long QT syndrome (LQTS) and proposals exist that using standing rather than supine electrocardiograms (ECG) improves the sensitivity of LQTS diagnosis. Nevertheless, compared to adults, children have higher heart rates (especially during postural provocations) and Bazett correction is also known to lead to artificially prolonged QTc values at increased heart rates. This study assessed the incidence of erroneously increased QTc values in normal children without QT abnormalities. Methods Continuous 12-lead ECGs were recorded in 332 healthy children (166 girls) aged 10.7 ± 2.6 years while they performed postural manoeuvring consisting of episodes (in the following order) of supine, sitting, standing, supine, standing, sitting, and supine positions, each lasting 10 min. Detailed analyses of QT/RR profiles confirmed the absence of prolonged individually corrected QTc interval in each child. Heart rate and QT intervals were measured in 10-s ECG segments and in each segment, QTc intervals were obtained using Bazett, Fridericia, and Framingham formulas. In each child, the heart rates and QTc values obtained during supine, sitting and standing positions were averaged. QTc durations by the three formulas were classified to < 440 ms, 440–460 ms, 460–480 ms, and > 480 ms. Results At supine position, averaged heart rate was 77.5 ± 10.5 beat per minute (bpm) and Bazett, Fridericia and Framingham QTc intervals were 425.3 ± 15.8, 407.8 ± 13.9, and 408.2 ± 13.1 ms, respectively. At sitting and standing, averaged heart rate increased to 90.9 ± 10.1 and 100.9 ± 10.5 bpm, respectively. While Fridericia and Framingham formulas showed only minimal QTc changes, Bazett correction led to QTc increases to 435 ± 15.1 and 444.9 ± 15.9 ms at sitting and standing, respectively. At sitting, Bazett correction identified 51, 4, and 0 children as having the QTc intervals 440–460, 460–480, and > 480 ms, respectively. At sitting, these numbers increased to 118, 11, and 1, while on standing these numbers were 151, 45, and 5, respectively. Irrespective of the postural position, Fridericia and Framingham formulas identified only a small number (< 7) of children with QT interval between 440 and 460 ms and no children with longer QTc. Conclusion During screening for LQTS in children, the use of Bazett formula leads to a high number of false positive cases especially if the heart rates are increased (e.g. by postural manoeuvring). The use of Fridericia formula can be recommended to replace the Bazett correction not only for adult but also for paediatric ECGs.
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Affiliation(s)
- Irena Andršová
- Department of Internal Medicine and Cardiology, Faculty of Medicine, University Hospital Brno, Masaryk University, Brno, Czech Republic
| | - Katerina Hnatkova
- National Heart and Lung Institute, Imperial College, ICTEM, Hammersmith Campus, 72 Du Cane Road, Shepherd's Bush, London, W12 0NN, England
| | - Kateřina Helánová
- Department of Internal Medicine and Cardiology, Faculty of Medicine, University Hospital Brno, Masaryk University, Brno, Czech Republic
| | - Martina Šišáková
- Department of Internal Medicine and Cardiology, Faculty of Medicine, University Hospital Brno, Masaryk University, Brno, Czech Republic
| | - Tomáš Novotný
- Department of Internal Medicine and Cardiology, Faculty of Medicine, University Hospital Brno, Masaryk University, Brno, Czech Republic
| | - Petr Kala
- Department of Internal Medicine and Cardiology, Faculty of Medicine, University Hospital Brno, Masaryk University, Brno, Czech Republic
| | - Marek Malik
- National Heart and Lung Institute, Imperial College, ICTEM, Hammersmith Campus, 72 Du Cane Road, Shepherd's Bush, London, W12 0NN, England.
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Mazzanti A, Guz D, Trancuccio A, Pagan E, Kukavica D, Chargeishvili T, Olivetti N, Biernacka EK, Sacilotto L, Sarquella-Brugada G, Campuzano O, Nof E, Anastasakis A, Sansone VA, Jimenez-Jaimez J, Cruz F, Sánchez-Quiñones J, Hernandez-Afonso J, Fuentes ME, Średniawa B, Garoufi A, Andršová I, Izquierdo M, Marinov R, Danon A, Expósito-García V, Garcia-Fernandez A, Muñoz-Esparza C, Ortíz M, Zienciuk-Krajka A, Tavazzani E, Monteforte N, Bloise R, Marino M, Memmi M, Napolitano C, Zorio E, Monserrat L, Bagnardi V, Priori SG. Natural History and Risk Stratification in Andersen-Tawil Syndrome Type 1. J Am Coll Cardiol 2020; 75:1772-1784. [PMID: 32299589 DOI: 10.1016/j.jacc.2020.02.033] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 01/25/2020] [Accepted: 02/11/2020] [Indexed: 11/25/2022]
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Andršová I, Hnatkova K, Helánová K, Šišáková M, Novotný T, Kala P, Malik M. Individually Rate Corrected QTc Intervals in Children and Adolescents. Front Physiol 2019; 10:994. [PMID: 31427990 PMCID: PMC6688657 DOI: 10.3389/fphys.2019.00994] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Accepted: 07/18/2019] [Indexed: 11/13/2022] Open
Abstract
Accurate evaluation of the appearance of QTc sex differences during childhood and adolescence is intricate. Inter-subject differences of individual QT/RR patterns make generic heart rate corrections inaccurate because of fast resting heart rates in children. The study investigated 527 healthy children and adolescents aged 4–19 years (268 females, 50.9%). All underwent continuous ECG 12-lead monitoring while performing postural changes during a 70-min investigative protocol to obtain QT interval measurements at different heart rates. On average, more than 1200 ECG measurements (QT interval and its 5-min history of preceding RR intervals) were made in each subject. Curvilinear QT/RR regression involving intra-individual correction for QT/RR hysteresis were calculated in each subject. The projection of the QT/RR regressions to the heart rate of 60 beats per minute defined individually corrected QTc intervals. In males, gradual QTc shortening by about 15 ms appeared during the ages of 13–19 years synchronously with the incidence of secondary sex signs (p = 0.016). On the contrary, whilst gradual QTc prolongation by about 10 ms appeared in females, it occurred only during ages 16–19 years and was not related to the incidence of secondary sex signs (p = 0.18). The study also showed that in children and adolescents, linear QT/RR models fit the intra-subject data significantly more closely than the log-linear models (p < 0.001). The study speculates that hormonal shifts during puberty might be directly responsible for the QTc shortening in males but that QTc prolongation in females is likely more complex since it was noted to follow the appearance of secondary sex signs only after a considerable delay.
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Affiliation(s)
- Irena Andršová
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Katerina Hnatkova
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Kateřina Helánová
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Martina Šišáková
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Tomáš Novotný
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Petr Kala
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Marek Malik
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
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13
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Manoušek J, Andršová I, Stejskal V, Vlašínová J, Sepši M, Kuta J, Klánová J, Mazík M, Jarkovský J, Šnajdrová L, Benešová K, Novotný T, Zadáková A, Špinar J. Hypersensitivity to material and environmental burden as a possible cause of late complications of cardiac implantable electronic devices. Europace 2019; 20:e140-e147. [PMID: 29016950 PMCID: PMC6123938 DOI: 10.1093/europace/eux227] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Accepted: 06/18/2017] [Indexed: 11/15/2022] Open
Abstract
Aims To evaluate whether patients with late complications of pacemakers or implantable cardioverter-defibrillators have hypersensitivity reactions to some of the materials used in generators or in electrodes, or to environmental metal burden. Methods and results The cohort consisted of 20 men and 4 women (mean age: 62.3 ± 17.2 years) who had a history of late complications of implanted devices. The control group involved 25 men and 8 women (mean age: 64.6 ± 14.0 years) who had comparable devices, but no history of late complications. Lymphocyte transformation test was used to evaluate hypersensitivity to eight metal pollutants (antimony, manganese, mercury, molybdenum, nickel, platinum, tin, and titanium) selected by results of questionnaires on environmental burden, and by material analysis of generators and electrode surfaces. Exposures to metal pollutants were approximately the same in patients and in controls. Titanium alloy used in generators contained at least 99.32% of titanium and trace levels of other metals; higher levels of tin and platinum were detected in electrode surfaces. Hypersensitivity reactions to mercury and tin were significantly more frequent in patients than in controls (patients and controls: mercury: 68.2 and 31.1%, respectively; P = 0.022; tin: 25.0 and 3.2%, respectively; P = 0.035). In contrast, hypersensitivity to manganese was significantly more frequent in controls than in patients (patients and controls: 13.6 and 50.0%, respectively; P = 0.008). Conclusion Our findings suggest a possible relation between hypersensitivity to metals used in implantable devices or to environmental metal burden and the occurrence of their late complications.
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Affiliation(s)
- Jan Manoušek
- Department of Internal Medicine and Cardiology, University Hospital Brno, Jihlavská 20, Brno, Czech Republic
| | - Irena Andršová
- Department of Internal Medicine and Cardiology, University Hospital Brno, Jihlavská 20, Brno, Czech Republic
| | - Vera Stejskal
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.,Faculty of Science, Research Centre for Toxic Compounds in the Environment (RECETOX), Masaryk University, Kamenice 753/5, pavillion A29, Brno, Czech Republic
| | - Jitka Vlašínová
- Department of Internal Medicine and Cardiology, University Hospital Brno, Jihlavská 20, Brno, Czech Republic
| | - Milan Sepši
- Department of Internal Medicine and Cardiology, University Hospital Brno, Jihlavská 20, Brno, Czech Republic.,Faculty of Medicine, Department of Internal Medicine and Cardiology, Masaryk University, Kamenice 753/5, Brno, Czech Republic
| | - Jan Kuta
- Faculty of Science, Research Centre for Toxic Compounds in the Environment (RECETOX), Masaryk University, Kamenice 753/5, pavillion A29, Brno, Czech Republic
| | - Jana Klánová
- Faculty of Science, Research Centre for Toxic Compounds in the Environment (RECETOX), Masaryk University, Kamenice 753/5, pavillion A29, Brno, Czech Republic
| | - Michal Mazík
- Methodical Centre for Conservation, Technical Museum in Brno, Purkynova 105, Brno, Czech Republic
| | - Jirí Jarkovský
- Faculty of Medicine, Department of Internal Medicine and Cardiology, Masaryk University, Kamenice 753/5, Brno, Czech Republic.,Faculty of Medicine, Institute of Biostatistics and Analyses, Masaryk University, Kamenice 126/3, Brno, Czech Republic
| | - Lenka Šnajdrová
- Faculty of Medicine, Institute of Biostatistics and Analyses, Masaryk University, Kamenice 126/3, Brno, Czech Republic
| | - Klára Benešová
- Faculty of Medicine, Institute of Biostatistics and Analyses, Masaryk University, Kamenice 126/3, Brno, Czech Republic
| | - Tomáš Novotný
- Department of Internal Medicine and Cardiology, University Hospital Brno, Jihlavská 20, Brno, Czech Republic.,Faculty of Science, Research Centre for Toxic Compounds in the Environment (RECETOX), Masaryk University, Kamenice 753/5, pavillion A29, Brno, Czech Republic
| | - Andrea Zadáková
- Department of Internal Medicine and Cardiology, University Hospital Brno, Jihlavská 20, Brno, Czech Republic
| | - Jindrich Špinar
- Department of Internal Medicine and Cardiology, University Hospital Brno, Jihlavská 20, Brno, Czech Republic.,Faculty of Science, Research Centre for Toxic Compounds in the Environment (RECETOX), Masaryk University, Kamenice 753/5, pavillion A29, Brno, Czech Republic
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Novotný T, Raudenská M, Kadlecová J, Andršová I, Floriánová A, Vašků A, Kozák M, Sepši M, Křivan L, Gaillyová R, Špinar J. Mutation analysis of ion channel genes promoters in ventricular fibrillation survivors with coronary artery disease. Cor Vasa 2013. [DOI: 10.1016/j.crvasa.2013.06.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Andršová I, Novotný T, Valášková I, Kadlecová J, Kuderová D, Sepši M, Kozák M, Křivan L, Gaillyová R, Špinar J. Mutation analysis of RyR2 gene in patients after arrhythmic storm. Cor Vasa 2012. [DOI: 10.1016/j.crvasa.2012.03.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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