1
|
Bury TM, Diagne K, Olshan D, Glass L, Shrier A, Lerman BB, Bub G. The inverse problem for cardiac arrhythmias. Chaos 2023; 33:123130. [PMID: 38149994 DOI: 10.1063/5.0161210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 11/20/2023] [Indexed: 12/28/2023]
Abstract
A cardiac arrhythmia is an abnormality in the rate or rhythm of the heart beat. We study a type of arrhythmia called a premature ventricular complex (PVC), which is typically benign, but in rare cases can lead to more serious arrhythmias or heart failure. There are three known mechanisms for PVCs: reentry, an ectopic focus, and triggered activity. We develop minimal models for each mechanism and attempt the inverse problem of determining which model (and therefore which mechanism) best describes the beat dynamics observed in an ambulatory electrocardiogram. We demonstrate our approach on a patient who exhibits frequent PVCs and find that their PVC dynamics are best described by a model of triggered activity. Better identification of the PVC mechanism from wearable device data could improve risk stratification for the development of more serious arrhythmias.
Collapse
Affiliation(s)
- T M Bury
- Department of Physiology, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec H3G 1Y6, Canada
| | - K Diagne
- Department of Physiology, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec H3G 1Y6, Canada
| | - D Olshan
- Department of Medicine, Division of Cardiology, Cornell University Medical Center, New York, New York 10065, USA
| | - L Glass
- Department of Physiology, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec H3G 1Y6, Canada
| | - A Shrier
- Department of Physiology, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec H3G 1Y6, Canada
| | - B B Lerman
- Department of Medicine, Division of Cardiology, Cornell University Medical Center, New York, New York 10065, USA
| | - G Bub
- Department of Physiology, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec H3G 1Y6, Canada
| |
Collapse
|
2
|
Biasci V, Santini L, Hussaini S, Ferrantini C, Coppini R, Loew LM, Luther S, Campione M, Poggesi C, Pavone FS, Cerbai E, Bub G, Sacconi L. Optogenetic manipulation of cardiac electrical dynamics using sub-threshold illumination: dissecting the role of cardiac alternans in terminating rapid rhythms. Cardiovasc Res 2022. [DOI: 10.1093/cvr/cvac066.161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Abstract
Funding Acknowledgements
Type of funding sources: None.
Cardiac action potential (AP) shape and propagation are regulated by several key dynamic factors such as ions channel recovery and intracellular Ca2+-cycling. Experimental methods for manipulating AP electrical dynamics commonly use ion channel inhibitors that lack spatial and temporal specificity. In this work, we propose a novel approach based on optogenetics to manipulate cardiac electrical activity employing a light-modulated depolarizing current with intensities that are too low to elicit APs (sub-threshold illumination) but are sufficient to fine-tune AP electrical dynamics. We investigated the effects of sub-threshold illumination in isolated cardiomyocytes and whole hearts by using transgenic mice constitutively expressing a light-gated ion channel (channelrhodopsins-2, ChR2). We find that ChR2-mediated depolarizing current prolongs APs and reduces conduction velocity (CV) in a space-selective and reversible manner. Sub-threshold manipulation also affects the dynamics of cardiac electrical activity, increasing the magnitude of cardiac alternans. We use an optical system that uses real-time feedback control to generate re-entrant circuits with user-defined cycle lengths to explore the role that cardiac alternans plays in spontaneous termination of ventricular tachycardias (VTs). We find that VT stability significantly decreases during sub-threshold illumination primarily due to an increase in the amplitude of electrical oscillations, which implies that cardiac alternans may be beneficial in the context of self-termination of VT.
Collapse
Affiliation(s)
- V Biasci
- LENS - European Laboratory for Non-Linear Spectroscopy, University of Florence , Sesto Fiorentino , Italy
| | - L Santini
- University of Florence, Dept NeuroFarBa , Florence , Italy
| | - S Hussaini
- Max Planck Institute for Dynamics and Self-Organization , Gottingen , Germany
| | - C Ferrantini
- University of Florence, Department of Experimental and Clinical Medicine , Firenze , Italy
| | - R Coppini
- University of Florence, Dept NeuroFarBa , Florence , Italy
| | - LM Loew
- University of Connecticut, Center for Cell Analysis and Modeling , Farmington , United States of America
| | - S Luther
- Max Planck Institute for Dynamics and Self-Organization , Gottingen , Germany
| | - M Campione
- University of Padua, Department of Biomedical Science , Padova , Italy
| | - C Poggesi
- University of Florence, Department of Experimental and Clinical Medicine , Firenze , Italy
| | - FS Pavone
- LENS - European Laboratory for Non-Linear Spectroscopy, University of Florence , Sesto Fiorentino , Italy
| | - E Cerbai
- LENS - European Laboratory for Non-Linear Spectroscopy, University of Florence , Sesto Fiorentino , Italy
| | - G Bub
- Mcgill University, Department of Physiology , Montreal , Canada
| | - L Sacconi
- LENS - European Laboratory for Non-Linear Spectroscopy, University of Florence , Sesto Fiorentino , Italy
| |
Collapse
|
3
|
Bury TM, Lerma C, Bub G, Laksman Z, Deyell MW, Glass L. Long ECGs reveal rich and robust dynamical regimes in patients with frequent ectopy. Chaos 2020; 30:113127. [PMID: 33261339 DOI: 10.1063/5.0023987] [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] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 10/26/2020] [Indexed: 06/12/2023]
Abstract
We have analyzed the electrocardiographic data collected during continuous 7-day ambulatory recordings in patients with frequent premature ventricular complexes (PVCs). We analyze the dependence of the frequency and patterns of PVCs on the heart rate and the time of the day. Patients display rhythms of a complex yet consistent structure. In a given patient, the pattern remains robust over different days and particular repetitive patterns appear at specific heart rates, suggesting the appearance of bifurcations in the dynamics. Over the course of 24 h, we find that in some patients, patterns appear to depend only on the heart rate, whereas in others, both the time of the day and the heart rate play a role in controlling the dynamics. Identifying parameter values at which bifurcations occur facilitates the development of dynamical models for arrhythmia. The use of powerful recording and analysis techniques will enable improved analysis of data and better understanding of mechanisms of arrhythmia in individual patients.
Collapse
Affiliation(s)
- T M Bury
- Department of Physiology, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec H3G 1Y6, Canada
| | - C Lerma
- Departamento de Instrumentación Electromecánica, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City 14080, Mexico
| | - G Bub
- Department of Physiology, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec H3G 1Y6, Canada
| | - Z Laksman
- Heart Rhythm Services, Division of Cardiology, University of British Columbia, Vancouver, British Columbia V6E 1M7, Canada
| | - M W Deyell
- Heart Rhythm Services, Division of Cardiology, University of British Columbia, Vancouver, British Columbia V6E 1M7, Canada
| | - L Glass
- Department of Physiology, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec H3G 1Y6, Canada
| |
Collapse
|
4
|
Bub G, Mongillo M, Smith G, Sacconi L. Novel optics-based approaches for cardiac electrophysiology. Prog Biophys Mol Biol 2020; 154:1-2. [PMID: 32407749 DOI: 10.1016/j.pbiomolbio.2020.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- G Bub
- Department of Physiology, McGill University, Canada
| | - M Mongillo
- Department of Cardiac, Thoracic, Vascular Sciences and Public Health, and Department of Biomedical Sciences, University of Padova, Italy
| | - G Smith
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, UK
| | - L Sacconi
- National Institute of Optics and European Laboratory for Non Linear Spectroscopy, Italy; Institute for Experimental Cardiovascular Medicine, University Freiburg, Germany.
| |
Collapse
|
5
|
Scardigli M, Müllenbroich C, Margoni E, Cannazzaro S, Crocini C, Ferrantini C, Coppini R, Yan P, Loew LM, Campione M, Bocchi L, Giulietti D, Cerbai E, Poggesi C, Bub G, Pavone FS, Sacconi L. Real-time optical manipulation of cardiac conduction in intact hearts. J Physiol 2018; 596:3841-3858. [PMID: 29989169 PMCID: PMC6117584 DOI: 10.1113/jp276283] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [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: 04/10/2018] [Accepted: 07/05/2018] [Indexed: 11/28/2022] Open
Abstract
Key points Although optogenetics has clearly demonstrated the feasibility of cardiac manipulation, current optical stimulation strategies lack the capability to react acutely to ongoing cardiac wave dynamics. Here, we developed an all‐optical platform to monitor and control electrical activity in real‐time. The methodology was applied to restore normal electrical activity after atrioventricular block and to manipulate the intraventricular propagation of the electrical wavefront. The closed‐loop approach was also applied to simulate a re‐entrant circuit across the ventricle. The development of this innovative optical methodology provides the first proof‐of‐concept that a real‐time all‐optical stimulation can control cardiac rhythm in normal and abnormal conditions.
Abstract Optogenetics has provided new insights in cardiovascular research, leading to new methods for cardiac pacing, resynchronization therapy and cardioversion. Although these interventions have clearly demonstrated the feasibility of cardiac manipulation, current optical stimulation strategies do not take into account cardiac wave dynamics in real time. Here, we developed an all‐optical platform complemented by integrated, newly developed software to monitor and control electrical activity in intact mouse hearts. The system combined a wide‐field mesoscope with a digital projector for optogenetic activation. Cardiac functionality could be manipulated either in free‐run mode with submillisecond temporal resolution or in a closed‐loop fashion: a tailored hardware and software platform allowed real‐time intervention capable of reacting within 2 ms. The methodology was applied to restore normal electrical activity after atrioventricular block, by triggering the ventricle in response to optically mapped atrial activity with appropriate timing. Real‐time intraventricular manipulation of the propagating electrical wavefront was also demonstrated, opening the prospect for real‐time resynchronization therapy and cardiac defibrillation. Furthermore, the closed‐loop approach was applied to simulate a re‐entrant circuit across the ventricle demonstrating the capability of our system to manipulate heart conduction with high versatility even in arrhythmogenic conditions. The development of this innovative optical methodology provides the first proof‐of‐concept that a real‐time optically based stimulation can control cardiac rhythm in normal and abnormal conditions, promising a new approach for the investigation of the (patho)physiology of the heart. Although optogenetics has clearly demonstrated the feasibility of cardiac manipulation, current optical stimulation strategies lack the capability to react acutely to ongoing cardiac wave dynamics. Here, we developed an all‐optical platform to monitor and control electrical activity in real‐time. The methodology was applied to restore normal electrical activity after atrioventricular block and to manipulate the intraventricular propagation of the electrical wavefront. The closed‐loop approach was also applied to simulate a re‐entrant circuit across the ventricle. The development of this innovative optical methodology provides the first proof‐of‐concept that a real‐time all‐optical stimulation can control cardiac rhythm in normal and abnormal conditions.
Collapse
Affiliation(s)
- M Scardigli
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,National Institute of Optics, National Research Council, Florence, 50125, Italy
| | - C Müllenbroich
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,National Institute of Optics, National Research Council, Florence, 50125, Italy
| | - E Margoni
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,Department of Physics, University of Pisa, Pisa, 56127, Italy
| | - S Cannazzaro
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,National Institute of Optics, National Research Council, Florence, 50125, Italy
| | - C Crocini
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,National Institute of Optics, National Research Council, Florence, 50125, Italy
| | - C Ferrantini
- Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence, Florence, 50134, Italy
| | - R Coppini
- Division of Pharmacology, Department 'NeuroFarBa', University of Florence, Florence, 50139, Italy
| | - P Yan
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, CT, 06030, USA
| | - L M Loew
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, CT, 06030, USA
| | - M Campione
- Neuroscience Institute, National Research Council, Padova, 35121, Italy.,Department of Biomedical Sciences, Univercity ot Padua, Padua, 35121, Italy
| | - L Bocchi
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,Department of Information Engineering, University of Florence, Via S. Marta 3, Florence, 50139, Italy
| | - D Giulietti
- National Institute of Optics, National Research Council, Florence, 50125, Italy.,Department of Physics, University of Pisa, Pisa, 56127, Italy
| | - E Cerbai
- Division of Pharmacology, Department 'NeuroFarBa', University of Florence, Florence, 50139, Italy
| | - C Poggesi
- Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence, Florence, 50134, Italy
| | - G Bub
- Department of Physiology, McGill University, Montreal, Quebec, Canada
| | - F S Pavone
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,National Institute of Optics, National Research Council, Florence, 50125, Italy.,Department of Physics and Astronomy, University of Florence, Sesto Fiorentino, 50019, Italy
| | - L Sacconi
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,National Institute of Optics, National Research Council, Florence, 50125, Italy
| |
Collapse
|
6
|
Burton R, Tomek J, Aslam S, Bilton S, Larsen H, Sharkey A, Stephens G, Mann E, Paterson D, Bub G. Sympathetic stellate neurons increases cardiac conduction velocity and alters wave patterns in a myocyte-neuron co-culture model system. Auton Neurosci 2015. [DOI: 10.1016/j.autneu.2015.07.062] [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: 10/23/2022]
|
7
|
Kalla M, Bub G, Paterson DJ, Herring N. 2 * Beta-blockers do not prevent the pro-arrhythmic action of high-level sympathetic stimulation: a role for neuropeptide Y? Europace 2014. [DOI: 10.1093/europace/euu236.2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
8
|
Bub G, Camelliti P, Bollensdorff C, Stuckey DJ, Picton G, Burton RAB, Clarke K, Kohl P. Measurement and analysis of sarcomere length in rat cardiomyocytes in situ and in vitro. Am J Physiol Heart Circ Physiol 2010; 298:H1616-25. [PMID: 20228259 DOI: 10.1152/ajpheart.00481.2009] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sarcomere length (SL) is an important determinant and indicator of cardiac mechanical function; however, techniques for measuring SL in living, intact tissue are limited. Here, we present a technique that uses two-photon microscopy to directly image striations of living cells in cardioplegic conditions, both in situ (Langendorff-perfused rat hearts and ventricular tissue slices, stained with the fluorescent marker di-4-ANEPPS) and in vitro (acutely isolated rat ventricular myocytes). Software was developed to extract SL from two-photon fluorescence image sets while accounting for measurement errors associated with motion artifact in raster-scanned images and uncertainty of the cell angle relative to the imaging plane. Monte-Carlo simulations were used to guide analysis of SL measurements by determining error bounds as a function of measurement path length. The mode of the distribution of SL measurements in resting Langendorff-perfused heart is 1.95 mum (n = 167 measurements from N = 11 hearts) after correction for tissue orientation, which was significantly greater than that in isolated cells (1.71 mum, n = 346, N = 9 isolations) or ventricular slice preparations (1.79 mum, n = 79, N = 3 hearts) under our experimental conditions. Furthermore, we find that edema in arrested Langendorff-perfused heart is associated with a mean SL increase; this occurs as a function of time ex vivo and correlates with tissue volume changes determined by magnetic resonance imaging. Our results highlight that the proposed method can be used to monitor SL in living cells and that different experimental models from the same species may display significantly different SL values under otherwise comparable conditions, which has implications for experiment design, as well as comparison and interpretation of data.
Collapse
Affiliation(s)
- G Bub
- Department of Physiology Anatomy and Genetics, Universityof Oxford, Oxfordshire, UK.
| | | | | | | | | | | | | | | |
Collapse
|
9
|
Bub G, Löwe A, Dialer K. Statistische Methoden bei der Untersuchung der Selbstvermischung in chemischen Reaktoren. CHEM-ING-TECH 2004. [DOI: 10.1002/cite.330431008] [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: 11/08/2022]
|
10
|
Abstract
According to the classic model initially formulated by Mines, reentrant cardiac arrhythmias may be associated with waves circulating in a ring geometry. This study was designed to study the dynamics of reentry in a ring geometry of cardiac tissue culture. Reentrant calcium waves in rings of cultured embryonic chick cardiac myocytes were imaged using a macroscope to monitor the fluorescence of intracellular Calcium Green-1 dye. The rings displayed a variety of stable rhythms including pacemaker activity and spontaneous reentry. Waves originating from a localized pacemaker could lead to reentry as a consequence of unidirectional block. In addition, more complex patterns were observed due to the interactions between reentrant and pacemaker rhythms. These rhythms included instances in which pacemakers accelerated the reentrant rhythm, and instances in which the excitation was blocked in the vicinity of pacemakers. During reentrant activity an appropriately timed electrical stimulus could induce resetting of activity or cause complete annihilation of the propagating waves. This experimental preparation reveals many spontaneously occuring complex rhythms. These complex rhythms are hypothesized to reflect interactions between spontaneous pacemakers, wave propagation, refractory period, and overdrive suppression. This preparation may serve as a useful model system to further investigate complex dynamics arising during reentrant rhythms in cardiac tissue.
Collapse
Affiliation(s)
- Hortensia González
- Laboratorio de Biofísica, Facultad de Ciencias, UNAM, México City, Mexico
| | | | | | | | | |
Collapse
|
11
|
Abstract
Rotating waves (rotors) of cellular activity were observed in nonconfluent cultures of embryonic chick heart cells by using a macroscopic imaging system that detected fluorescence from intracellular Ca2+. Unlike previous observations of rotors or spiral waves in other systems, the rotors did not persist but exhibited a repetitive pattern of spontaneous onset and offset leading to a bursting rhythm. Similar dynamics were observed in a cellular automaton model of excitable media that incorporates spontaneous initiation of activity, and a decrease of excitability as a consequence of rapid activity (fatigue). These results provide a mechanism for bursting dynamics in normal and pathological biological processes.
Collapse
Affiliation(s)
- G Bub
- Department of Physiology, McGill University, 3655 Drummond Street, Montreal, QC Canada, H3G 1Y6
| | | | | | | |
Collapse
|
12
|
Bub G, Hög HU. On the rhodium catalyzed formation of acetic acid from methyl formate — comparison with the rhodium catalyzed formation of acetic acid by direct carbonylation of methanol. ACTA ACUST UNITED AC 1995. [DOI: 10.1016/1381-1169(94)00161-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
13
|
Bub G, Baerns M. Answer to Goyal's, Bakhshi's and Esmail's letter to the editors. Chem Eng Sci 1984. [DOI: 10.1016/0009-2509(84)80163-3] [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: 10/17/2022]
|
14
|
|
15
|
Bub G, Löwe A, Dialer K. Parameter-Ermittlung für Modelle der Selbstvermischung. CHEM-ING-TECH 1970. [DOI: 10.1002/cite.330420805] [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: 11/07/2022]
|