SPIRAL FORMATION IN A BELOUSOV-ZHABOTINSKY MEDIUM BY PREMATURE RE-EXCITATION: VULNERABILITY

1994 ◽  
Vol 04 (05) ◽  
pp. 1193-1204 ◽  
Author(s):  
M. GÓMEZ-GESTEIRA ◽  
G. FERNÁNDEZ-GARCÍA ◽  
A.P. MUÑUZURI ◽  
V. PÉREZ-MUÑUZURI ◽  
V.I. KRINSKY ◽  
...  
Keyword(s):  
Cardiac Tissue ◽  
Conditioning Stimulus ◽  
Heart Rhythm ◽  
Critical Value ◽  
Spiral Waves ◽  
Spatial Extent ◽  
The Third ◽  
Isotropic Diffusion ◽  
Life Threatening ◽  
Third Dimension

Spiral waves can be initiated in cardiac tissue by first stimulating it with a conditioning stimulus and then by a test stimulus at a different site. Because the resulting heart rhythm can be life threatening, this behaviour has been widely treated and the interval of time between conditioning and test stimuli has been labelled vulnerability. We hypothesize that the anisotropic cardiac structure was not essential for spiral initiation and reproduced it in a Belousov-Zhabotinsky (BZ) medium, which is continuous and characterized by isotropic diffusion coefficients. We observe that the different spatial extent of the medium (systems “quasi” 1D, 2D or 3D) influences the evolution of the test wave front. Even when the spatial extent of the third dimension exceeds a critical value, the region of vulnerability can disappear.

scholarly journals Overdrive pacing of spiral waves in a model of human ventricular tissue

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Sergei F. Pravdin ◽  
Timofei I. Epanchintsev ◽  
Alexander V. Panfilov
Keyword(s):  
Cardiac Arrhythmias ◽  
Cardiac Tissue ◽  
Low Voltage ◽  
Spiral Waves ◽  
High Frequency Stimulation ◽  
In Silico Study ◽  
Restitution Curve ◽  
Life Threatening ◽  
Frequency Stimulation ◽  
Human Cardiac Tissue

AbstractHigh-voltage electrical defibrillation remains the only reliable method of quickly controlling life-threatening cardiac arrhythmias. This paper is devoted to studying an alternative approach, low-voltage cardioversion (LVC), which is based on ideas from non-linear dynamics and aims to remove sources of cardiac arrhythmias by applying high-frequency stimulation to cardiac tissue. We perform a detailed in-silico study of the elimination of arrhythmias caused by rotating spiral waves in a TP06 model of human cardiac tissue. We consider three parameter sets with slopes of the APD restitution curve of 0.7, 1.1 and 1.4, and we study LVC at the baseline and under the blocking of INa and ICaL and under the application of the drugs verapamil and amiodarone. We show that pacing can remove spiral waves; however, its efficiency can be substantially reduced by dynamic instabilities. We classify these instabilities and show that the blocking of INa and the application of amiodarone increase the efficiency of the method, while the blocking of ICaL and the application of verapamil decrease the efficiency. We discuss the mechanisms and the possible clinical applications resulting from our study.

Taking Cell Culture in Drug Discovery to the Third Dimension - A Patent Review

2008 ◽  
Vol 1 (2) ◽  
pp. 103-115
Author(s):  
Yinzhi Lai ◽  
Lina Wang ◽  
Ke Cheng ◽  
William Kisaalita
Keyword(s):  
Cell Culture ◽  
Drug Discovery ◽  
The Third ◽  
Patent Review ◽  
Third Dimension

La troisième dimension — De la fonction éthique et esthétique du décor dans le théâtre de machines français du XVIIe siècle

2020 ◽  
Vol 71 (1) ◽  
pp. 130-168
Author(s):  
Kirsten Dickhaut
Keyword(s):  
Seventeenth Century ◽  
Character Traits ◽  
Optical Illusion ◽  
Stage Design ◽  
The Third ◽  
Adequate Representation ◽  
Third Dimension ◽  
Xviie Siecle ◽  
The Aesthetic

AbstractThe machine theatre in France achieves its peak in the second half of the seventeenth century. It is the construction of machines that permits the adequate representation of the third dimension on stage. This optical illusion is created by flying characters, as heroes, gods, or demons moving horizontally and vertically. The enumeration indicates that only characters possessing either ethically exemplary character traits or incorporating sin are allowed to fly. Therefore, the third dimension indicates bienséance – or its opposite. According to this, the following thesis is deduced: The machine theatre illustrates via aesthetic concerns characterising its third dimension an ethic foundation. Ethic and aesthetics determine each other in the context of both, decorum and in theatre practice. In order to prove this thesis three steps are taken. First of all, the machine theatre’s relationship to imitation and creation is explored. Second, the stage design, representing the aesthetic benefits of the machines in service of the third dimension, are explained. Finally, the concrete example of Pierre Corneille’s Andromède is analysed by pointing out the role of Pegasus and Perseus.

scholarly journals Rivaroxaban-Induced Nontraumatic Spinal Subdural Hematoma: An Uncommon Yet Life-Threatening Complication

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Mazen Zaarour ◽  
Samer Hassan ◽  
Nishitha Thumallapally ◽  
Qun Dai
Keyword(s):  
Subdural Hematoma ◽  
Lower Risk ◽  
Oral Anticoagulants ◽  
Factor Xa ◽  
Bleeding Events ◽  
Spinal Hematoma ◽  
The Third ◽  
Spinal Subdural Hematoma ◽  
Life Threatening ◽  
Life Threatening Complication

In the last decade, the desire for safer oral anticoagulants (OACs) led to the emergence of newer drugs. Available clinical trials demonstrated a lower risk of OACs-associated life-threatening bleeding events, including intracranial hemorrhage, compared to warfarin. Nontraumatic spinal hematoma is an uncommon yet life-threatening neurosurgical emergency that can be associated with the use of these agents. Rivaroxaban, one of the newly approved OACs, is a direct factor Xa inhibitor. To the best of our knowledge, to date, only two published cases report the incidence of rivaroxaban-induced nontraumatic spinal subdural hematoma (SSDH). Our case is the third one described and the first one to involve the cervicothoracic spine.

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