scholarly journals Voltage/Calcium Uncoupling Underlies Sustained Torsade de Pointes Ventricular Tachyarrhythmia in an Experimental Model of Long QT Syndrome

2021 ◽  
Vol 12 ◽  
Author(s):  
Herman D. Himel ◽  
Michael Cupelli ◽  
Mohamed Boutjdir ◽  
Nabil El-Sherif
Keyword(s):  
Guinea Pig ◽  
Wave Front ◽  
Experimental Model ◽  
Long Qt Syndrome ◽  
Analytical Method ◽  
Ventricular Tachyarrhythmia ◽  
Torsade De Pointes ◽  
Long Qt ◽  
Qt Syndrome ◽  
Electrophysiological Mechanism

BackgroundClinical experience showed that the majority of Torsade de Pointes (TdP) ventricular tachyarrhythmia (VT) in patients with long QT syndrome (LQTS) are self-terminating (ST), but the few that are non-self-terminating (NST) are potentially fatal. A paramount issue in clinical arrhythmology is to understand the electrophysiological mechanism of ST vs. NST TdP VT.MethodsWe investigated the electrophysiological mechanism of ST vs. NST TdP VT in the guinea pig Anthopleurin-A experimental model of LQTS, a close surrogate model of congenital LQT3. We utilized simultaneous optical recordings of membrane voltage (Vm) and intracellular calcium (Cai) and a robust analytical method based on spatiotemporal entropy difference (Ed) to investigate the hypothesis that early Vm/Cai uncoupling during TdP VT can play a primary role in perpetuation of VT episodes.ResultsWe analyzed a total of 35 episodes of TdP VT from 14 guinea pig surrogate models of LQTS, including 23 ST and 12 NST VTs. Ed values for NST VT were significantly higher than Ed values for ST VT. Analysis of wave front topology during the early phase of ST VT showed the Cai wave front following closely Vm wave front consistent with a lower degree of Ed. In contrast, NST VT was associated with uncoupling of Vm/Cai wave fronts during the first 2 or 3 cycles of VT associated with early wave break propagation pattern.ConclusionsUtilizing a robust analytical method we showed that, in comparison to ST TdP VT, NST VT was consistently predated by early uncoupling of Vm/Cai that destabilized wave front propagation and can explain a sustained complex reentrant excitation pattern.

scholarly journals Long QT in stunned myocardium: unrecognised cause of acquired long QT syndrome

2014 ◽  
Vol 83 (3) ◽  
pp. 250-254
Author(s):  
Jerzy Sacha
Keyword(s):  
Long Qt Syndrome ◽  
Qt Interval ◽  
Ventricular Tachyarrhythmia ◽  
Torsade De Pointes ◽  
Stunned Myocardium ◽  
Long Qt ◽  
Wave Inversion ◽  
Qt Interval Prolongation ◽  
Evolutionary Changes ◽  
Qt Syndrome

Long QT syndrome (LQTS) is a heart disorder characterized by a prolongation of the QT interval on ECG and a predisposition to ventricular tachyarrhythmias, which may lead to syncope, cardiac arrest or sudden cardiac death. This condition may be inherited or induced by external factors such as drugs, electrolyte imbalances and some acquired cardiac diseases. The review addresses LQTS caused by acute cardiac illnesses which are associated with a large amount of stunned myocardium, i.e. the reperfused myocardial infarction and the group of stress-related cardiomyopathies. In these cases, specific ECG evolutionary changes may be observed, i.e. dynamic deep T-wave inversion and QT interval prolongation which predispose to fatal polymorphic ventricular tachyarrhythmia, i.e. torsade de pointes. However, lethal arrhythmias are relatively rare in these instances and probably concern patients with an underlying predisposition to LQTS. The pathological mechanisms of both repolarization abnormalities and ventricular arrhythmias as well as the practical approach how to interpret electrocardiographic changes and identify high risk patients are discussed in this review.

Antiarrhythmic Effects of Ranolazine in a Guinea Pig in Vitro Model of Long-QT Syndrome

2004 ◽  
Vol 310 (2) ◽  
pp. 599-605 ◽  
Author(s):  
Lin Wu ◽  
John C. Shryock ◽  
Yejia Song ◽  
Yuan Li ◽  
Charles Antzelevitch ◽  
...  
Keyword(s):  
Guinea Pig ◽  
Long Qt Syndrome ◽  
In Vitro Model ◽  
Long Qt ◽  
Qt Syndrome ◽  
Vitro Model ◽  
Antiarrhythmic Effects

Acquired long QT syndrome and torsade de pointes

2018 ◽  
Vol 41 (4) ◽  
pp. 414-421 ◽  
Author(s):  
Nabil El-Sherif ◽  
Gioia Turitto ◽  
Mohamed Boutjdir
Keyword(s):  
Long Qt Syndrome ◽  
Torsade De Pointes ◽  
Long Qt ◽  
Acquired Long Qt Syndrome ◽  
Qt Syndrome

The Electrophysiological Mechanism of Ventricular Arrhythmias in the Long QT Syndrome

1996 ◽  
Vol 79 (3) ◽  
pp. 474-492 ◽  
Author(s):  
Nabil El-Sherif ◽  
Edward B. Caref ◽  
Hong Yin ◽  
Mark Restivo
Keyword(s):  
Long Qt Syndrome ◽  
Ventricular Arrhythmias ◽  
Long Qt ◽  
Qt Syndrome ◽  
Electrophysiological Mechanism

scholarly journals Complex and Novel Arrhythmias Precede Stillbirth in Fetuses With De Novo Long QT Syndrome

2020 ◽  
Vol 13 (5) ◽  
Author(s):  
Sarah Strand ◽  
Janette F. Strasburger ◽  
Bettina F. Cuneo ◽  
Ronald T. Wakai
Keyword(s):  
Atrioventricular Block ◽  
Long Qt Syndrome ◽  
De Novo ◽  
Perinatal Death ◽  
Torsade De Pointes ◽  
Fetal Loss ◽  
Long Qt ◽  
Premature Ventricular Contractions ◽  
Fetal Magnetocardiography ◽  
Qt Syndrome

Background: Long QT syndrome (LQTS) is a leading cause of sudden cardiac death in early life and has been implicated in ≈10% of sudden infant deaths and unexplained stillbirths. The purpose of our study was to use fetal magnetocardiography to characterize the electrophysiology and rhythm phenotypes of fetuses with de novo and inherited LQTS variants and identify risk factors for sudden death before birth. Methods: We reviewed the fetal magnetocardiography database from the University of Wisconsin Biomagnetism Laboratory for fetuses with confirmed LQTS. We assessed waveform intervals, heart rate, and rhythm, including the signature LQTS rhythms: functional 2° atrioventricular block, T-wave alternans, and torsade de pointes (TdP). Results: Thirty-nine fetuses had pathogenic variants in LQTS genes: 27 carried the family variant, 11 had de novo variants, and 1 was indeterminate. De novo variants, especially de novo SCN5A variants, were strongly associated with a severe rhythm phenotype and perinatal death: 9 (82%) showed signature LQTS rhythms, 6 (55%) showed TdP, 5 (45%) were stillborn, and 1 (9%) died in infancy. Those that died exhibited novel fetal rhythms, including atrioventricular block with 3:1 conduction ratio, QRS alternans in 2:1 atrioventricular block, long-cycle length TdP, and slow monomorphic ventricular tachycardia. Premature ventricular contractions were also strongly associated with TdP and perinatal death. Fetuses with familial variants showed a lower incidence of signature LQTS rhythm (6/27=22%), including TdP (3/27=11%). All were live born. Conclusions: The malignancy of de novo LQTS variants was remarkably high and demonstrate that these mutations are a significant cause of stillbirth. Their ability to manifest rhythms not known to be associated with LQTS increases the difficulty of echocardiographic diagnosis and decreases the likelihood that a resultant fetal loss is attributed to LQTS. Registration: URL: http://www.clinicaltrials.gov . Unique identifier: NCT03047161.

scholarly journals Successful trans-maternal nadolol pharmacotherapy in a fetus presenting with long QT syndrome type 2 complicated by torsade de pointes

2020 ◽  
Vol 22 (6) ◽  
pp. 265-268
Author(s):  
Yuriko Shima ◽  
Hitoshi Horigome ◽  
Yoshihiro Nozaki ◽  
Lisheng Lin ◽  
Takumi Ishiodori ◽  
...  
Keyword(s):  
Long Qt Syndrome ◽  
Torsade De Pointes ◽  
Syndrome Type ◽  
Long Qt ◽  
Qt Syndrome
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