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Lewetag RD, Nimani S, Alerni N, Hornyik T, Jacobi SF, Moss R, Menza M, Pilia N, Walz TP, HajiRassouliha A, Perez-Feliz S, Zehender M, Seemann G, Zgierski-Johnston CM, Lopez R, Odening KE. Mechano-electrical interactions and heterogeneities in wild-type and drug-induced long QT syndrome rabbits. J Physiol 2023. [PMID: 37082830 DOI: 10.1113/jp284604] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 04/18/2023] [Indexed: 04/22/2023] Open
Abstract
BACKGROUND Electromechanical reciprocity - comprising electro-mechanical (EMC) and mechano-electric coupling (MEC) - provides cardiac adaptation to changing physiological demands. Understanding electromechanical reciprocity and its impact on function and heterogeneity in pathological conditions - such as (drug-induced) acquired long QT syndrome (aLQTS) - might lead to novel insights in arrhythmogenesis. Our aim is to investigate how electrical changes impact on mechanical function (EMC) and vice versa (MEC) under physiological conditions and in aLQTS. METHODS To measure regional differences in EMC and MEC in vivo, we used tissue phase mapping cardiac MRI and 24-lead ECG vest in healthy (control) and IKr -blocker E-4031-induced aLQTS rabbit hearts. MEC was studied in vivo by acutely increasing cardiac preload, and ex vivo by using voltage optical mapping in beating hearts at different preloads. RESULTS In aLQTS, electrical repolarization (heart rate corrected RT-interval, RTn370) was prolonged compared to control (p<0.0001) with increased spatial and temporal RT heterogeneity (p<0.01). Changing electrical function (in aLQTS) resulted in significantly reduced diastolic mechanical function and prolonged contraction duration (EMC), causing increased apico-basal mechanical heterogeneity. Increased preload acutely prolonged RTn370 in both control and aLQTS hearts (MEC). This effect was more pronounced in aLQTS (p<0.0001). Additionally, regional RT-dispersion increased in aLQTS. Motion-correction allowed to determine APD-prolongation in beating aLQTS hearts, but limited motion correction accuracy upon preload-changes prevented a clear analysis of MEC ex vivo. CONCLUSION Mechano-induced RT-prolongation and increased heterogeneity were more pronounced in aLQTS than in healthy hearts. Acute MEC effects may play an additional role in LQT-related arrhythmogenesis, warranting further mechanistic investigations. KEY POINT SUMMARY Electromechanical reciprocity - comprising excitation-contraction coupling (EMC) and mechano-electric feedback loops (MEC) - is essential for physiological cardiac function. Alterations in electrical and/or mechanical heterogeneity are known to have potentially pro-arrhythmic effects. In this study, we aimed to investigate how electrical changes impact on the mechanical function (EMC) and vice versa (MEC) - both under physiological conditions (control) and in acquired long QT syndrome (aLQTS). We show that changing the electrical function (in aLQTS) results in significantly altered mechanical heterogeneity via EMC and - vice versa - that increasing the preload acutely prolongs repolarization duration and increases electrical heterogeneity, particularly in aLQTS as compared to control. Our results substantiate the hypothesis that LQTS is an 'electro-mechanical' - rather than a 'purely electrical' - disease and suggest that acute MEC effects may play an additional role in LQT-related arrhythmogenesis. Abstract figure legend Electromechanical reciprocity in healthy (control) and acquired long QT syndrome (aLQTS) rabbit hearts. A.-B. Electrical alteration in aLQTS. A. Exemplary ECG traces demonstrating IKr -blocker E-4031-induced RT prolongation in aLQTS. B. Visualization of heart rate corrected RTn370 (each color-coded scale includes 20ms) on rabbits' torso in aLQTS compared to control (n = 6 each). C. Electro-mechanical coupling (EMC). Exemplary myocardial longitudinal velocity curve in base (cm/s) during cardiac cycle in control (blue) and aLQTS (red). Indicated are peak amplitudes (AMPsys, AMPdia) and time-to-diastolic peak (TTPdia). D. Mechano-electrical coupling (MEC). Box plots of preload induced changes in repolarization. Comparison between the timepoints baseline (15 sec before increase in preload) and time of the maximal RTn370 increase peak-preload (around 20 sec after NaCl bolus injection). Heart rate corrected RTn370 demonstrates more pronounced RT-changes in aLQTS compared to control (n = 13 each). This article is protected by copyright. All rights reserved.
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Affiliation(s)
- R D Lewetag
- Department of Cardiology and Angiology I, University Heart Center Freiburg, University Medical Center Freiburg, Freiburg, Germany
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - S Nimani
- Translational Cardiology, Department of Cardiology and Department of Physiology, University Hospital Bern, Bern, Switzerland
| | - N Alerni
- Translational Cardiology, Department of Cardiology and Department of Physiology, University Hospital Bern, Bern, Switzerland
| | - T Hornyik
- Department of Cardiology and Angiology I, University Heart Center Freiburg, University Medical Center Freiburg, Freiburg, Germany
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen and Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Translational Cardiology, Department of Cardiology and Department of Physiology, University Hospital Bern, Bern, Switzerland
| | - S F Jacobi
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen and Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Department of Congenital Heart Defects and Pediatric Cardiology, University Heart Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - R Moss
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen and Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach-Institute EMI, Freiburg, Germany
| | - M Menza
- Department of Radiology, Medical Physics, University Hospital Freiburg, and Faculty of Medicine, University of Freiburg, Germany
| | - N Pilia
- Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - T Puig Walz
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen and Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach-Institute EMI, Freiburg, Germany
| | | | - S Perez-Feliz
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - M Zehender
- Department of Cardiology and Angiology I, University Heart Center Freiburg, University Medical Center Freiburg, Freiburg, Germany
| | - G Seemann
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - C M Zgierski-Johnston
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - R Lopez
- Translational Cardiology, Department of Cardiology and Department of Physiology, University Hospital Bern, Bern, Switzerland
| | - K E Odening
- Department of Cardiology and Angiology I, University Heart Center Freiburg, University Medical Center Freiburg, Freiburg, Germany
- Translational Cardiology, Department of Cardiology and Department of Physiology, University Hospital Bern, Bern, Switzerland
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Lewetag R, Hornyik T, Jacobi S, Moss R, Pilia N, Menza M, Perez-Feliz S, Bode C, Seemann G, Odening KE. Electro-mechanical and mechano-electrical interactions in healthy and drug-induced LQTS rabbit hearts. Europace 2021. [DOI: 10.1093/europace/euab116.578] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Funding Acknowledgements
Type of funding sources: Foundation. Main funding source(s): German Research Foundation
Background
Electrical and mechanical heterogeneities and their interactions (electro-mechanical and mechano-electrical coupling; EMC / MEC) are essential for normal cardiac function. Alterations in these can result in increased arrhythmia formation.
Purpose
With this study, we aim to investigate EMC and MEC under physiological and pathological conditions to better understand their roles in arrhythmia development.
Methods
Multi-channel ECG and TPM-MRI were used to measure regional differences in EMC in healthy ("control") and IKr-blocker E-4031 induced acute LQTS ("E-4031") rabbit hearts in vivo. MEC was studied in both groups by acutely changing mechanical function (increased preload by 6 ml/kg BW bolus of NaCl).
Results
In acute LQTS hearts (E-4031 10µg/kg bolus + 1µg/(kg*min) iv), cardiac repolarization was markedly prolonged compared to healthy controls, (p < 0.0001; n = 13), with increased QT-dispersion (Max-Min), a marker for regional heterogeneity of repolarization (p < 0.01; n = 13).
Changing electrical function by E-4031 resulted in changes of mechanical features (EMC): in acute LQTS hearts, diastolic longitudinal velocity (Vz) was reduced in all basal (p = 0.003; n = 19) and 4/6 mid segments (p = 0.006; n = 19). Longitudinal diastolic TTP was prolonged significantly in 5/6 basal and 4/6 mid segments by E-4031. These alterations led to an increased apicobasal heterogeneity of longitudinal contraction duration (basal-apical Vz_dia_TTP [ms] 2.9 ± 10.6 vs. 21.1 ± 21.3; p = 0.01; n = 9).
Increased preload acutely prolonged QTc in both "control" and "E-4031" hearts (‘control’ 156.6 ± 11.6 to 198.3 ± 20.3; p < 0.0001 vs. ‘E-4031’ 193.9 ± 19.6 to 256.0 ± 37.5; p < 0.0001; n = 13) (MEC). This effect was more pronounced in "E-4031" acute LQTS hearts than in healthy hearts (Figure 1; delta QTc [ms] ‘control’ 41.6 ± 14.9 vs. ‘E4031’ 62.1 ± 32.1; p < 0.006, n = 13). QT-dispersion (Max-Min) was increased significantly upon mechanical change only in "E-4031" (‘E-4031’ 25.8 ± 5.5 to 32.7 ± 12.3; p < 0.03, n = 13).
Conclusion
E-4031-induced changes in electrical function resulted in marked alterations in mechanical features via EMC. Similarly, acute changes in mechanical function (increased preload) resulted in electrical changes via MEC. Importantly, QT-prolonging effects of acutely increased preload, as well as its effects on regional heterogeneity of repolarization, were more pronounced in E-4031-induced acute LQTS hearts, indicating that cardiac repolarization in LQTS may be more susceptible to acute MEC effects than in healthy hearts. Acute MEC effects may thus play an additional role in LQT-related arrhythmogenesis. Abstract Figure.
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Affiliation(s)
- R Lewetag
- University Heart Center Freiburg, Department of Cardiology and Angiology I, Freiburg, Germany
| | - T Hornyik
- Bern University Hospital, Inselspital, Department of Cardiology and Department of Physiology, Bern, Switzerland
| | - S Jacobi
- University Heart Center Freiburg, Department of Pediatric Cardiology, Freiburg, Germany
| | - R Moss
- University Heart Center Freiburg, Institute for Experimental Cardiovascular Medicine, Freiburg, Germany
| | - N Pilia
- Karlsruhe Institute of Technology (KIT), Institute of Biomedical Engineering, Karlsruhe, Germany
| | - M Menza
- University Hospital of Freiburg, Department of Radiology, Freiburg, Germany
| | - S Perez-Feliz
- University Heart Center Freiburg, Institute for Experimental Cardiovascular Medicine, Freiburg, Germany
| | - C Bode
- University Heart Center Freiburg, Department of Cardiology and Angiology I, Freiburg, Germany
| | - G Seemann
- University Heart Center Freiburg, Institute for Experimental Cardiovascular Medicine, Freiburg, Germany
| | - KE Odening
- Bern University Hospital, Inselspital, Department of Cardiology and Department of Physiology, Bern, Switzerland
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Pilia N, Severi S, Raimann JG, Genovesi S, Dössel O, Kotanko P, Corsi C, Loewe A. Quantification and classification of potassium and calcium disorders with the electrocardiogram: What do clinical studies, modeling, and reconstruction tell us? APL Bioeng 2020; 4:041501. [PMID: 33062908 PMCID: PMC7532940 DOI: 10.1063/5.0018504] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 09/13/2020] [Indexed: 11/14/2022] Open
Abstract
Diseases caused by alterations of ionic concentrations are frequently observed challenges and play an important role in clinical practice. The clinically established method for the diagnosis of electrolyte concentration imbalance is blood tests. A rapid and non-invasive point-of-care method is yet needed. The electrocardiogram (ECG) could meet this need and becomes an established diagnostic tool allowing home monitoring of the electrolyte concentration also by wearable devices. In this review, we present the current state of potassium and calcium concentration monitoring using the ECG and summarize results from previous work. Selected clinical studies are presented, supporting or questioning the use of the ECG for the monitoring of electrolyte concentration imbalances. Differences in the findings from automatic monitoring studies are discussed, and current studies utilizing machine learning are presented demonstrating the potential of the deep learning approach. Furthermore, we demonstrate the potential of computational modeling approaches to gain insight into the mechanisms of relevant clinical findings and as a tool to obtain synthetic data for methodical improvements in monitoring approaches.
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Affiliation(s)
- N Pilia
- Institute of Biomedical Engineering, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany
| | - S Severi
- Department of Electrical, Electronic, and Information Engineering "Guglielmo Marconi," University of Bologna, 47522 Cesena, Italy
| | - J G Raimann
- Renal Research Institute, New York, New York 10065, USA
| | - S Genovesi
- Department of Medicine and Surgery, University of Milan-Bicocca, 20100 Milan, Italy
| | - O Dössel
- Institute of Biomedical Engineering, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany
| | | | - C Corsi
- Department of Electrical, Electronic, and Information Engineering "Guglielmo Marconi," University of Bologna, 47522 Cesena, Italy
| | - A Loewe
- Institute of Biomedical Engineering, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany
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