Mechanical Communication Between Cardiac Cell Leads to Synchrony in Beating

2012 ◽  
Author(s):  
Xin Tang ◽  
Piyush Bajaj ◽  
Rashid Bashir ◽  
Taher Saif
Keyword(s):  
Atrial Fibrillation ◽  
Elastic Modulus ◽  
Cardiac Cells ◽  
Cardiac Cell ◽  
Atrial Wall ◽  
Coupled Dynamics ◽  
Deformable Media ◽  
Chemical Signalling ◽  
The Media ◽  
Isolated Cardiac Cells

It is generally understood that cardiac cells synchronize their beating through electro-chemical signalling. Here we show, theoretically and experimentally, that isolated cardiac cells can communicate with each other through an intervening deformable media. Such communication leads to coupled dynamics and emergence of synchronous beating. The interaction between the cells depends inversely with the elastic modulus of the media, and the distance between them. This finding may explain asynchronous beating of the atrium in patients with atrial fibrillation where the stiffness of the atrial wall becomes significantly harder due to fibrosis [1].

The Role of Atrial Fibrosis Detected by Delayed - Enhancement MRI in Atrial Fibrillation Ablation

2020 ◽  
Vol 16 (2) ◽  
pp. 135-144 ◽  
Author(s):  
Zsuzsanna Kis ◽  
Astrid Amanda Hendriks ◽  
Taulant Muka ◽  
Wichor M. Bramer ◽  
Istvan Kovacs ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Imaging Modality ◽  
Final Analysis ◽  
Atrial Fibrosis ◽  
Atrial Wall ◽  
Af Ablation ◽  
Left Atrial Wall ◽  
Cmr Imaging

Introduction: Atrial Fibrillation (AF) is associated with remodeling of the atrial tissue, which leads to fibrosis that can contribute to the initiation and maintenance of AF. Delayed- Enhanced Cardiac Magnetic Resonance (DE-CMR) imaging for atrial wall fibrosis detection was used in several studies to guide AF ablation. The aim of present study was to systematically review the literature on the role of atrial fibrosis detected by DE-CMR imaging on AF ablation outcome. Methods: Eight bibliographic electronic databases were searched to identify all published relevant studies until 21st of March, 2016. Search of the scientific literature was performed for studies describing DE-CMR imaging on atrial fibrosis in AF patients underwent Pulmonary Vein Isolation (PVI). Results: Of the 763 citations reviewed for eligibility, 5 articles (enrolling a total of 1040 patients) were included into the final analysis. The overall recurrence of AF ranged from 24.4 - 40.9% with median follow-up of 324 to 540 days after PVI. With less than 5-10% fibrosis in the atrial wall there was a maximum of 10% recurrence of AF after ablation. With more than 35% fibrosis in the atrial wall there was 86% recurrence of AF after ablation. Conclusion: Our analysis suggests that more extensive left atrial wall fibrosis prior ablation predicts the higher arrhythmia recurrence rate after PVI. The DE-CMR imaging modality seems to be a useful method for identifying the ideal candidate for catheter ablation. Our findings encourage wider usage of DE-CMR in distinct AF patients in a pre-ablation setting.

Electrophysiology of the Sodium-Potassium-ATPase in Cardiac Cells

2001 ◽  
Vol 81 (4) ◽  
pp. 1791-1826 ◽  
Author(s):  
Helfried Günther Glitsch
Keyword(s):  
Cell Membrane ◽  
Potential Gradient ◽  
Outward Current ◽  
Pump Current ◽  
Cardiac Cells ◽  
Animal Cells ◽  
Excitable Cells ◽  
Extracellular Medium ◽  
Enzymatic Isolation ◽  
Isolated Cardiac Cells

Like several other ion transporters, the Na+-K+ pump of animal cells is electrogenic. The pump generates the pump current I p. Under physiological conditions, I p is an outward current. It can be measured by electrophysiological methods. These methods permit the study of characteristics of the Na+-K+ pump in its physiological environment, i.e., in the cell membrane. The cell membrane, across which a potential gradient exists, separates the cytosol and extracellular medium, which have distinctly different ionic compositions. The introduction of the patch-clamp techniques and the enzymatic isolation of cells have facilitated the investigation of I p in single cardiac myocytes. This review summarizes and discusses the results obtained from I p measurements in isolated cardiac cells. These results offer new exciting insights into the voltage and ionic dependence of the Na+-K+ pump activity, its effect on membrane potential, and its modulation by hormones, transmitters, and drugs. They are fundamental for our current understanding of Na+-K+ pumping in electrically excitable cells.

Fluorescence and differential light absorption recordings with calcium probes and potential-sensitive dyes in skinned cardiac cells

1982 ◽  
Vol 60 (4) ◽  
pp. 556-567 ◽  
Author(s):  
Alexandre Fabiato
Keyword(s):  
Cardiac Cells ◽  
Arsenazo Iii ◽  
Optical Methods ◽  
Cardiac Cell ◽  
Differential Absorption ◽  
Fluorescence Measurements ◽  
Merocyanine 540 ◽  
Inverted Microscope ◽  
Optimum Wavelength ◽  
Absorption Measurements

This report describes an optical system for microspectrophotometry in a single cardiac cell from which the sarcolemma has been removed by microdissection (skinned cardiac cell). This system is attached to the high power inverted microscope used for the microdissection and includes (a) a single variable wavelength microspectrophotometer used to define the spectrum of a given dye or Ca2+ probe; and (b) a dual wavelength, differential microspectrophotometer used to record differentially between the optimum wavelength and a wavelength separated by 25–30 nm. Results are presented using the following optical methods: (a) fluorescence measurements with chlorotetracycline to monitor the amount of Ca2+ bound to the inner face of the sarcoplasmic reticulum (SR) membrane; (b) differential absorption measurements with arsenazo III to measure changes of myoplasmic [Ca2+]free resulting from Ca2+ release from the SR; (c) fluorescence and (or) differential absorption measurements with the potential-sensitive dyes merocyanine 540, NK 2367, and di-S-C3(5) to monitor changes of charge distribution on the SR membrane during Ca2+ accumulation in the SR, as well as before and during Ca2+-induced release of Ca2+ from the SR. A small and rapid signal is observed which precedes the Ca2+-induced release of Ca2+ from the SR. It is detected as an increase of Ca2+ binding inside the SR with chlorotetracycline and as a "hyperpolarization" with potential-sensitive dyes, while no transient change of myoplasmic [Ca2+]free is detected with arsenazo III. This small and rapid signal preceding the Ca2+ release may be a first hint to an understanding of the mechanism whereby a small increase of [Ca2+]free outside the SR triggers Ca2+ release from the SR.

Abstract 15570: Direct Evidence of Endo-Epicardial Dissociation of the Atrial Wall in Patients With Longstanding Persistent Atrial Fibrillation

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Natasja de Groot ◽  
Lisette vd Does ◽  
Ameeta Yaksh ◽  
Paul Knops ◽  
Pieter Woestijne ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Direct Evidence ◽  
Persistent Atrial Fibrillation ◽  
Right Atrial ◽  
Electrode Arrays ◽  
Atrial Wall ◽  
Ablative Therapies ◽  
Epicardial Layer ◽  
Right Atrial Appendage ◽  
The Right

Introduction: Transition of paroxysmal to longstanding persistent atrial fibrillation (LsPAF) is associated with progressive longitudinal dissociation in conduction and a higher incidence of focal fibrillation waves. The aim of this study was to provide direct evidence that the substrate of LsPAF consists of an electrical double-layer of dissociated waves, and that focal fibrillation waves are caused by endo-epicardial breakthrough. Hypothesis: LsPAF in humans is caused by electrical dissociation of the endo- and epicardial layer. Methods: Intra-operative mapping of the endo- and epicardial right atrial wall was performed in 9 patients with induced (N=4), paroxysmal (N=1), persistent (N=2) or longstanding-persistent AF (N=2). A clamp of two rectangular electrode-arrays (128 electrodes; inter-electrode distance 2mm) was introduced through an incision in the right atrial appendage. Series of 10 seconds of AF were analyzed and the incidence of endo-epicardial dissociation (≥15ms) was determined for all 128 endo-epicardial recording sites. Results: In patients with LsPAF the averaged degree of endo-epicardial dissociation was highest (24.9% vs. 5.9%). Using strict criteria for breakthrough (presence of an opposite wave within 4mm and <15ms before the origin of the focal wave), the far majority (77%) of all focal fibrillation waves could be attributed to endo-epicardial excitation. Conclusions: During LsPAF considerable differences in activation of the right endo- and epicardial wall exist. Endo-epicardial fibrillation waves that are out of phase, may conduct transmurally and create breakthrough waves in the opposite layer. This may explain the high persistence of AF and the low succes rate of ablative therapies in patients with LsPAF.

659Left atrial wall thickness evaluation during atrial fibrillation redo procedures

EP Europace ◽  
2020 ◽  
Vol 22 (Supplement_1) ◽  
Author(s):  
C Teres ◽  
D Soto ◽  
B Jauregui ◽  
D Penela ◽  
A Ordonez ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Wall Thickness ◽  
Atrial Wall ◽  
Ablation Procedure ◽  
Left Atrial Wall ◽  
Local Distance ◽  
The Mean ◽  
The Right ◽  
The Relationship ◽  
Funding Acknowledgements

Abstract Funding Acknowledgements Dr Teres was funded by Swiss Heartrhythm Foundation Introduction pulmonary vein (PV) reconnections due to gaps on circumferential ablation lines are responsible for atrial fibrillation recurrences after catheter ablation. We sought to analyze the local left atrial wall thickness (LAWT) of PV line gaps at AF redo ablation during real-time catheter positioning. LAWT was measured on the MDCT 3D reconstruction and fused with the LA anatomy using CARTO-merge. Objective To analyze the relationship between local reconnection gaps and the LAWT during AF redo procedures. Methods Single-Center cohort study that included 41 consecutive patients referred for AF redo procedure. All patients had a MDCT prior to the ablation procedure. LAWT maps were semi-automatically computed from the MDCT as the local distance between the LA endo and epicardium. Each PV line was subdivided into 8 segments and mean LAWT was computed. During the procedure, the local gap was defined as the earliest activation site at the reconnected segment of the circumferential PV line (Figure 1A & 1B). Results 41 patients [31 (75.6%) male, age 60 ± 10 years] were included. Mean LAWT was 1.36 ± 0.20 mm. Mean PV circumferential line WT was higher in left PVs than in the right PVs 1.68 ± 0.57 vs. 1.31 ± 0.39 mm p &lt; 0.001 respectively. Mean WT of the reconnected points was 44% higher than the mean WT of the segment where the reconnection was located. Mean reconnection point WT was at the 87th percentile of the circumferential line in the LPVs and at the 76th percentile in the RPVs. The reconnected point WT was higher in the LPVs than RPVs 2.13 ± 1.14 vs. 1.47 ± 0.48 mm p &lt; 0.001 respectively.  The most frequent location for reconnections was the left anterior carina (71%), with a mean WT of 2.24 ± 0.91mm; and the right anterior carina (56%) with a mean WT of 1.57 ± 0.62mm (Figure 2A & 2B). Conclusions Reconnection points were more frequently present in the thicker segments of the PV circumferential line. The most frequently reconnected segment was the anterior carina in both right and left PVs. Atrial wall thickness maps derived from MDCT are useful to guide AF redo procedures. Abstract Figure. 1) Activation & WT map; 2) Segment WT

scholarly journals Disordered Myocardial Ca2+ Homeostasis Results in Substructural Alterations That May Promote Occurrence of Malignant Arrhythmias

2016 ◽  
pp. S139-S148 ◽  
Author(s):  
N. TRIBULOVA ◽  
V. KNEZL ◽  
B. SZEIFFOVA BACOVA ◽  
T. EGAN BENOVA ◽  
C. VICZENCZOVA ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Intact Animal ◽  
Electron Microscopic Examination ◽  
Atrial Pacing ◽  
Cardiac Cell ◽  
Cell Coupling ◽  
Electron Microscopic ◽  
Tissue Samples ◽  
The Impact ◽  
Malignant Arrhythmias

We aimed to determine the impact of Ca2+-related disorders induced in intact animal hearts on ultrastructure of the cardiomyocytes prior to occurrence of severe arrhythmias. Three types of acute experiments were performed that are known to be accompanied by disturbances in Ca2+ handling. Langedorff-perfused rat or guinea pig hearts subjected to K+-deficient perfusion to induce ventricular fibrillation (VF), burst atrial pacing to induce atrial fibrillation (AF) and open chest pig heart exposed to intramyocardial noradrenaline infusion to induce ventricular tachycardia (VT). Tissue samples for electron microscopic examination were taken during basal condition, prior and during occurrence of malignant arrhythmias. Cardiomyocyte alterations preceding occurrence of arrhythmias consisted of non-uniform sarcomere shortening, disruption of myofilaments and injury of mitochondria that most likely reflected cytosolic Ca2+ disturbances and Ca2+ overload. These disorders were linked with non-uniform pattern of neighboring cardiomyocytes and dissociation of adhesive junctions suggesting defects in cardiac cell-to-cell coupling. Our findings identified heterogeneously distributed high [Ca2+]i-induced subcellular injury of the cardiomyocytes and their junctions as a common feature prior occurrence of VT, VF or AF. In conclusion, there is a link between Ca2+-related disorders in contractility and coupling of the cardiomyocytes pointing out a novel paradigm implicated in development of severe arrhythmias.

scholarly journals Clinical correlates of echocardiographic tissue velocity imaging abnormalities of the left atrial wall during atrial fibrillation

EP Europace ◽  
2014 ◽  
Vol 16 (11) ◽  
pp. 1546-1553 ◽  
Author(s):  
I. Limantoro ◽  
C. B. de Vos ◽  
T. Delhaas ◽  
B. Weijs ◽  
Y. Blaauw ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Left Atrial ◽  
Atrial Wall ◽  
Clinical Correlates ◽  
Tissue Velocity ◽  
Velocity Imaging ◽  
Left Atrial Wall
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