scholarly journals Pulsed low-energy stimulation initiates electric turbulence in cardiac tissue

2021 ◽  
Vol 17 (10) ◽  
pp. e1009476
Author(s):  
Rupamanjari Majumder ◽  
Sayedeh Hussaini ◽  
Vladimir S. Zykov ◽  
Stefan Luther ◽  
Eberhard Bodenschatz
Keyword(s):  
Cardiac Tissue ◽  
Chronic Atrial Fibrillation ◽  
Low Energy ◽  
Nonlinear Wave Propagation ◽  
Excitable Systems ◽  
Spatially Extended ◽  
Life Threatening ◽  
The Creation ◽  
Illumination Regime ◽  
Wave Break

Interruptions in nonlinear wave propagation, commonly referred to as wave breaks, are typical of many complex excitable systems. In the heart they lead to lethal rhythm disorders, the so-called arrhythmias, which are one of the main causes of sudden death in the industrialized world. Progress in the treatment and therapy of cardiac arrhythmias requires a detailed understanding of the triggers and dynamics of these wave breaks. In particular, two very important questions are: 1) What determines the potential of a wave break to initiate re-entry? and 2) How do these breaks evolve such that the system is able to maintain spatiotemporally chaotic electrical activity? Here we approach these questions numerically using optogenetics in an in silico model of human atrial tissue that has undergone chronic atrial fibrillation (cAF) remodelling. In the lesser studied sub-threshold illumination régime, we discover a new mechanism of wave break initiation in cardiac tissue that occurs for gentle slopes of the restitution characteristics. This mechanism involves the creation of conduction blocks through a combination of wavefront-waveback interaction, reshaping of the wave profile and heterogeneous recovery from the excitation of the spatially extended medium, leading to the creation of re-excitable windows for sustained re-entry. This finding is an important contribution to cardiac arrhythmia research as it identifies scenarios in which low-energy perturbations to cardiac rhythm can be potentially life-threatening.

scholarly journals Myopericarditis Associated with COVID-19 in a Pediatric Patient with Kidney Failure Receiving Hemodialysis

Pathogens ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 486
Author(s):  
Marcela Daniela Ionescu ◽  
Mihaela Balgradean ◽  
Catalin Gabriel Cirstoveanu ◽  
Ioana Balgradean ◽  
Loredana Ionela Popa ◽  
...  
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Replacement Therapy ◽  
Female Patient ◽  
Pediatric Patient ◽  
Kidney Failure ◽  
Cardiac Tissue ◽  
Pulmonary Involvement ◽  
Rt Pcr ◽  
Acute Pericarditis ◽  
Life Threatening

The outbreak of COVID-19 can be associated with cardiac and pulmonary involvement and is emerging as one of the most significant and life-threatening complications in patients with kidney failure receiving hemodialysis. Here, we report a critically ill case of a 13-year-old female patient with acute pericarditis and bilateral pleurisy, screened positive for SARS-CoV-2 RT-PCR, presented with high fever, frequent dry cough, and dyspnea with tachypnea. COVID-19-induced myopericarditis has been noted to be a complication in patients with concomitant kidney failure with replacement therapy (KFRT). This article brings information in the light of our case experience, suggesting that the direct effect of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on cardiac tissue was a significant contributor to myopericarditis in our patient. Further studies in this direction are required, as such associations have thus far been reported.

scholarly journals Optogenetic currents in myofibroblasts acutely alter electrophysiology and conduction of co-cultured cardiomyocytes

2020 ◽  
Author(s):  
Geran Kostecki ◽  
Yu Shi ◽  
Christopher Chen ◽  
Daniel H. Reich ◽  
Emilia Entcheva ◽  
...  
Keyword(s):  
Cardiac Tissue ◽  
Cardiac Injury ◽  
Neonatal Rat ◽  
Culture Studies ◽  
Electrophysiological Properties ◽  
Inward Currents ◽  
Life Threatening ◽  
Cultured Cardiomyocytes ◽  
Cardiac Myofibroblasts

AbstractInteractions between cardiac myofibroblasts and myocytes may slow conduction after cardiac injury, increasing the chance of life-threatening arrhythmia. While co-culture studies have shown that myofibroblasts can affect cardiomyocyte electrophysiology in vitro, the mechanism(s) remain debatable. In this study, primary neonatal rat cardiac myofibroblasts were transduced with the light-activated ion channel Channelrhodopsin-2, which allowed acute and selective modulation of myofibroblast currents in co-cultures with cardiomyocytes. Optical mapping revealed that myofibroblast-specific optogenetically induced inward currents decreased conduction velocity in the co-cultures by 27±6% (baseline = 17.7±5.3 cm/s), and shortened the cardiac action potential duration by 14±7% (baseline = 161±11 ms) when 0.017 mW/mm2 light was applied. When light irradiance was increased to 0.057 mW/mm2, the myofibroblast currents led to spontaneous beating in 6/7 co-cultures. Experiments showed that optogenetic perturbation did not lead to changes in myofibroblast strain and force generation, suggesting purely electrical effects in this model. In silico modeling of optogenetically modified myofibroblast-cardiomyocyte co-cultures largely reproduced these results and enabled a comprehensive study of relevant parameters. These results clearly demonstrate that myofibroblasts are sufficiently electrically connected to cardiomyocytes to effectively alter macroscopic electrophysiological properties in this model of cardiac tissue.

Electrophysiological heterogeneity and stability of reentry in simulated cardiac tissue

2001 ◽  
Vol 280 (2) ◽  
pp. H535-H545 ◽  
Author(s):  
Fagen Xie ◽  
Zhilin Qu ◽  
Alan Garfinkel ◽  
James N. Weiss
Keyword(s):  
Action Potential ◽  
Action Potential Duration ◽  
Cardiac Tissue ◽  
Potential Model ◽  
Dynamic Instability ◽  
Spatial Scales ◽  
Cardiac Cells ◽  
Dynamic Factors ◽  
Cardiac Model ◽  
Wave Break

Generation of wave break is a characteristic feature of cardiac fibrillation. In this study, we investigated how dynamic factors and fixed electrophysiological heterogeneity interact to promote wave break in simulated two-dimensional cardiac tissue, by using the Luo-Rudy (LR1) ventricular action potential model. The degree of dynamic instability of the action potential model was controlled by varying the maximal amplitude of the slow inward Ca2+ current to produce spiral waves in homogeneous tissue that were either nearly stable, meandering, hypermeandering, or in breakup regimes. Fixed electrophysiological heterogeneity was modeled by randomly varying action potential duration over different spatial scales to create dispersion of refractoriness. We found that the degree of dispersion of refractoriness required to induce wave break decreased markedly as dynamic instability of the cardiac model increased. These findings suggest that reducing the dynamic instability of cardiac cells by interventions, such as decreasing the steepness of action potential duration restitution, may still have merit as an antifibrillatory strategy.

APERIODIC NONCHAOTIC ATTRACTORS, STRANGE AND OTHERWISE

2007 ◽  
Vol 17 (10) ◽  
pp. 3397-3407 ◽  
Author(s):  
AWADHESH PRASAD ◽  
AMITABHA NANDI ◽  
RAMAKRISHNA RAMASWAMY
Keyword(s):  
New Developments ◽  
The Past ◽  
Excitable Systems ◽  
Potential Applications ◽  
The Creation ◽  
Strange Nonchaotic Attractors ◽  
Important Objective

The main conceptual issues in the study of strange nonchaotic dynamics have been summarized and reviewed earlier [Prasad et al., 2001]. In the past five years, there has been further progress in the analysis of such attractors, and in understanding the nature of dynamical transitions in quasiperiodically forced systems. Here we discuss new developments which include the creation of strange nonchaotic attractors in excitable systems, the elucidation of the mechanisms for the intermittent and fractalization routes to SNA as well as their potential applications. The possibility of creating such attractors without recourse to quasiperiodic forcing is an important objective, and this has been realized in specific circumstances.

scholarly journals The promise and challenge of systems biology in translational medicine

2012 ◽  
Vol 124 (6) ◽  
pp. 389-390 ◽  
Author(s):  
Visith Thongboonkerd
Keyword(s):  
Systems Biology ◽  
Translational Medicine ◽  
Cardiac Tissue ◽  
Prognostic Markers ◽  
Sugar Metabolism ◽  
Amino Sugar ◽  
Cycle Arrest ◽  
Life Threatening ◽  
Dependent Cell ◽  
Late Stages

Abnormalities in clinical parameters and routine laboratory tests are frequently detected at late stages of many diseases (too late to cure or to prevent life-threatening complications). Hence earlier diagnostic and prognostic markers are needed for decision making and improving therapeutic outcome. In the present issue of Clinical Science, Rudiger and co-workers report findings from a transcriptomic study, which revealed that changes in transcripts involved in amino-sugar metabolism, p53-dependent cell-cycle arrest, β-adrenergic signalling and intracellular calcium cycling in cardiac tissue of rats with early sepsis could discriminate survivors from non-survivors. These findings underscore the great potential of systems biology in translational medicine. However, further investigations should be done to make the benchside results more feasible for routine clinical practice.

Internal right atrial cardioversion of chronic atrial fibrillation: Effects of low-energy biphasic shocks

1998 ◽  
Vol 82 (10) ◽  
pp. 1285-1286 ◽  
Author(s):  
Jacques Mansourati ◽  
Valérie Valls-Bertault ◽  
Jean-Marie Larlet ◽  
Benoit Maheu ◽  
Marc Hero ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Chronic Atrial Fibrillation ◽  
Low Energy ◽  
Right Atrial

TEMPORAL EVOLUTION OF NONLINEAR DYNAMICS IN VENTRICULAR ARRHYTHMIA

2001 ◽  
Vol 11 (10) ◽  
pp. 2531-2548 ◽  
Author(s):  
MICHAEL SMALL ◽  
DEJIN YU ◽  
ROBERT G. HARRISON ◽  
RICHARD CLAYTON ◽  
TRYGVE EFTESTØL ◽  
...  
Keyword(s):  
Cardiac Tissue ◽  
Surrogate Data ◽  
Mapping Technique ◽  
Ecg Signals ◽  
Return Mapping ◽  
Industrialized Nations ◽  
Spatially Extended ◽  
Observation Function ◽  
Scroll Wave ◽  
Break Up

Ventricular fibrillation (VF) is a rapidly lethal cardiac arrhythmia and one of the leading causes of sudden death in many industrialized nations. VF appears at random, but is produced by a spatially extended excitable system. We generated VF-like "pseudo-ECG" signals from a numerical caricature of cardiac tissue of 100 × 100 × 50 elements. The VF-like "pseudo-ECG" signals represent the propagation and break-up of an excitation scroll wave under FitzHugh–Nagumo dynamics. We use surrogate data and correlation dimension techniques to show that the dynamics observed in these computational simulations is consistent with the evolution of spontaneous VF in humans. Furthermore, we apply a novel adaptation of the traditional first return map technique to show that scroll wave break-up may be represented by a characteristic structural transition in the first return plot. The patterns and features identified by the first return mapping technique are found to be independent of the observation function and location. These methods offer insight into the evolution of VF and hint at potential new methods for diagnosis and analysis of this rapidly lethal condition.

scholarly journals Spontaneous Sublingual Haematoma in a 90-year Old Patient: A Complication of Direct Oral Anticoagulants

2020 ◽  
Vol 6 (2) ◽  
pp. 111-114
Author(s):  
Johannes Daniël Cnossen ◽  
Jeannette Fenna Schoonderbeek ◽  
Maaike Muller
Keyword(s):  
Rare Complication ◽  
Oral Anticoagulants ◽  
Direct Oral Anticoagulants ◽  
Upper Airway ◽  
Chronic Atrial Fibrillation ◽  
Fresh Frozen Plasma ◽  
Nasal Intubation ◽  
Fresh Frozen ◽  
Life Threatening ◽  
Frozen Plasma

AbstractSublingual haematoma is a rare complication of anticoagulants and can be life-threatening. As the number of prescribed anticoagulants is increasing, the incidence of complications of these drugs will continue to increase. A report of a sublingual haematoma in an elderly patient with chronic atrial fibrillation treated with edoxban (Lixiana ©, Daiichi Sankyo Europe GmbH, München, Germany) is reported. A 90-year male presented at the emergency department with an obstructed upper airway due to a sublingual haematoma. The patient received tranexamic acid, prothrombin complex, and fresh frozen plasma. After fiberoptic nasal intubation, the patient was monitored in the intensive care unit. After four days, the patient was extubated, and after six days, the swelling resolved completely. Complications of anticoagulants are rare but can be life-threatening. Recognition of an endangered airway and reversing the effects of the anticoagulant are essential. Surgical evacuation of the haematoma could be considered but is not necessary.

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