Heart Electrical Activity during Ventricular Repolarization in Subjects with Different Resistances to Hypoxia

2019 ◽  
Vol 45 (6) ◽  
pp. 634-641
Author(s):  
E. V. Zamenina ◽  
N. I. Panteleeva ◽  
I. M. Roshchevskaya
Keyword(s):  
Electrical Activity ◽  
Ventricular Repolarization ◽  
Heart Electrical Activity

Effect of Drugs on the Heart Electrical Activity of Man

1970 ◽  
Vol 10 (2) ◽  
pp. 95-102 ◽  
Author(s):  
CARL C. PFEIFFER ◽  
MOHINDER SINGH ◽  
LEONIDE GOLDSTEIN
Keyword(s):  
Electrical Activity ◽  
Heart Electrical Activity

scholarly journals A Simplified 3D Model of Whole Heart Electrical Activity and 12-Lead ECG Generation

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Siniša Sovilj ◽  
Ratko Magjarević ◽  
Nigel H. Lovell ◽  
Socrates Dokos
Keyword(s):  
Electrical Activity ◽  
Three Dimensional ◽  
Model Complexity ◽  
Bidomain Model ◽  
Computationally Efficient ◽  
Lead System ◽  
Heart Electrical Activity ◽  
Cell Tissue ◽  
Whole Heart ◽  
Electrocardiogram Ecg

We present a computationally efficient three-dimensional bidomain model of torso-embedded whole heart electrical activity, with spontaneous initiation of activation in the sinoatrial node, incorporating a specialized conduction system with heterogeneous action potential morphologies throughout the heart. The simplified geometry incorporates the whole heart as a volume source, with heart cavities, lungs, and torso as passive volume conductors. We placed four surface electrodes at the limbs of the torso: , , and and six electrodes on the chest to simulate the Einthoven, Goldberger-augmented and precordial leads of a standard 12-lead system. By placing additional seven electrodes at the appropriate torso positions, we were also able to calculate the vectorcardiogram of the Frank lead system. Themodel was able to simulate realistic electrocardiogram (ECG) morphologies for the 12 standard leads, orthogonal , , and leads, as well as the vectorcardiogram under normal and pathological heart states. Thus, simplified and easy replicable 3D cardiac bidomain model offers a compromise between computational load and model complexity and can be used as an investigative tool to adjust cell, tissue, and whole heart properties, such as setting ischemic lesions or regions of myocardial infarction, to readily investigate their effects on whole ECG morphology.

scholarly journals T vector velocity: A new ECG biomarker for identifying drug effects on cardiac ventricular repolarization

2018 ◽  
Author(s):  
Werner Bystricky ◽  
Christoph Maier ◽  
Gary Gintant ◽  
Dennis Bergau ◽  
Kent Kamradt ◽  
...  
Keyword(s):  
Electrical Activity ◽  
Drug Effects ◽  
Ventricular Repolarization ◽  
The Body ◽  
Calcium Currents ◽  
Published Data ◽  
Ion Currents ◽  
Vector Velocity ◽  
Surface Ecg ◽  
Auc Value

AbstractWe present a new family TrX of ECG biomarkers based on the T vector velocity (TVV) for assessing drug effects on ventricular repolarization. Assuming a link between the TVV and the instantaneous change of the cellular action potentials, drugs accelerating repolarization by blocking inward (depolarizing) ion currents cause a relative increase of the TVV, while drugs delaying repolarization by blocking outward ion currents cause a relative decrease of the TVV.Evaluating the published data from two FDA funded studies, the TrX effect profiles indicate increasingly delayed electrical activity over the entire repolarization process for drugs solely reducing outward potassium current (dofetilide, moxifloxacin). For drugs eliciting block of the inward sodium or calcium currents (mexiletine, lidocaine), the TrX effect profiles were consistent with accelerated electrical activity in the initial repolarization phase. For multichannel blocking drugs (ranolazine) or drug combinations blocking multiple ion currents (dofetilide + mexiletine, dofetilide + lidocaine), the overall TrX effect profiles indicate a superposition of the individual TrX effect profiles.The parameter Tr40c allows separating pure potassium channel blocking drugs from multichannel blocking drugs with an area under the ROC curve (AUC) value of 0.90, CI = [0.88 to 0.92]. This is significantly larger than the performance of J-Tpeakc (0.81, CI = [0.78 to 0.84]) using the published data from the second FDA study. Further performance improvement was achieved by combining the ten parameters Tr10c to Tr100c in a logistic regression model, resulting in an AUC value of 0.94.The TVV based approach substantially improves assessment of drug effects on cardiac repolarization, providing a plausible and improved mechanistic link between drug effects on ionic currents and overall ventricular repolarization reflected in the body surface ECG. TVV may contribute to a better assessment of the proarrhythmic risk of drugs beyond QTc prolongation and JTpeakc.

scholarly journals Simplified 2D Bidomain Model of Whole Heart Electrical Activity and ECG Generation

2014 ◽  
Vol 14 (3) ◽  
pp. 136-143 ◽  
Author(s):  
Siniša Sovilj ◽  
Ratko Magjarević ◽  
Amr Al Abed ◽  
Nigel H. Lovell ◽  
Socrates Dokos
Keyword(s):  
Electrical Activity ◽  
Sinoatrial Node ◽  
Biophysical Model ◽  
Model Complexity ◽  
Lead System ◽  
Heart Electrical Activity ◽  
Cardiac Model ◽  
Surface Ecg ◽  
Whole Heart ◽  
Ecg Morphology

Abstract The aim of this study was the development of a geometrically simple and highly computationally-efficient two dimensional (2D) biophysical model of whole heart electrical activity, incorporating spontaneous activation of the sinoatrial node (SAN), the specialized conduction system, and realistic surface ECG morphology computed on the torso. The FitzHugh-Nagumo (FHN) equations were incorporated into a bidomain finite element model of cardiac electrical activity, which was comprised of a simplified geometry of the whole heart with the blood cavities, the lungs and the torso as an extracellular volume conductor. To model the ECG, we placed four electrodes on the surface of the torso to simulate three Einthoven leads VI, VII and VIII from the standard 12-lead system. The 2D model was able to reconstruct ECG morphology on the torso from action potentials generated at various regions of the heart, including the sinoatrial node, atria, atrioventricular node, His bundle, bundle branches, Purkinje fibers, and ventricles. Our 2D cardiac model offers a good compromise between computational load and model complexity, and can be used as a first step towards three dimensional (3D) ECG models with more complex, precise and accurate geometry of anatomical structures, to investigate the effect of various cardiac electrophysiological parameters on ECG morphology.

scholarly journals Vitamin E administration attenuates the tri-iodothyronine-induced modification of heart electrical activity in the rat.

1997 ◽  
Vol 200 (5) ◽  
pp. 909-914
Author(s):  
P Venditti ◽  
T De Leo ◽  
S Di Meo
Keyword(s):  
Lipid Peroxidation ◽  
Heart Rate ◽  
Free Radical ◽  
Vitamin E ◽  
Thyroid Hormone ◽  
Action Potential ◽  
Electrical Activity ◽  
Radical Mechanism ◽  
Antioxidant Systems ◽  
Heart Electrical Activity

This work was designed to determine whether the thyroid-hormone-induced modifications of heart electrical activity are, at least in part, due to increased free radical production. For this study, 60-day-old euthyroid, hyperthyroid and hyperthyroid vitamin-E-treated rats were used. Hyperthyroidism, elicited by a 10 day treatment with tri-iodothyronine, induced an increase in lipid peroxidation without changing the level of antioxidants. Intraperitoneal vitamin administration to hyperthyroid rats led to a reduction in lipid peroxidation and a non-significant increase in antioxidant level. The hyperthyroid state was also associated with an increase in heart rate measured in vivo and a decrease in the duration of the ventricular action potential recorded in vitro. Administration of vitamin E attenuated the thyroid-hormone-induced changes in heart rate and action potential duration, which were, however, significantly different from those of the control euthyroid rats. These results suggest that vitamin E protects hyperthyroid heart against lipid peroxidation by mechanisms that may be independent of the changes in antioxidant systems. Moreover, the reduction in the tri-iodothyronine effects on heart electrophysiological properties indicates that such effects are mediated, at least in part, through a membrane modification, probably related to increased lipid peroxidation, involving a free radical mechanism.

scholarly journals Return of spontaneous circulation and heart rhythm during the first analysis of the heart electrical activity

2019 ◽  
Vol 18 (3) ◽  
pp. 147-150
Author(s):  
Sebastian Kowalski ◽  
Adrian Moskal ◽  
Karolina Żak-Kowalska ◽  
Mariusz Goniewicz
Keyword(s):  
Cardiac Arrest ◽  
Electrical Activity ◽  
Statistical Significance ◽  
Sudden Cardiac Arrest ◽  
Heart Rhythm ◽  
Spontaneous Circulation ◽  
Return Of Spontaneous Circulation ◽  
Heart Electrical Activity ◽  
First Moment ◽  
The Relationship

AbstractIntroduction. Return of spontaneous circulation (ROSC) of a patient with cardiac arrest is the main goal of carrying out cardiopulmonary resuscitation.Aim. Evaluation of frequency of return of spontaneous circulation depending on the heart rhythms in the first moment of heart electrical activity.Material and methods. Analysis of 105 cases of sudden cardiac arrest in out-of-hospital conditions on the premises of Brzozow Emergency Medical Service from September 2016 to the end of February 2018. The data was collected from intervention medical cards and medical rescue procedure cards. Statistical analysis was carried out using STATISTICA software. Statistical significance was assumed to be p<0.05.Results. Sudden cardiac arrest in the analysed group applied to 62.9% of men. Return of spontaneous circulation was achieved only in 16 out of 105 cases (15.2%) of sudden cardiac arrest. The analysis has indicated that ROSC was successful among 66.67% of patients, who during the first analysis of the rhythm, represented cardiac arrest in VF/pVT, what constituted 75% of all ROSC cases in the analysed group. Comparison between ROSC and rhythm during the first evaluation of the rhythm showed statistical significance (p=0.00). Statistical significance was also shown in the relationship between ROSC and the average age of the patient (p=0.0155).Conclusions. Sudden cardiac arrest, when diagnosed in the first analysis of the rhythm VF/pVT, has bigger chances for return of spontaneous circulation than it has in other rhythms.

Interrelation between the number of ectopic foci and the chaoticity degree of ventricular fibrillation

2018 ◽  
pp. 11-16
Author(s):  
Л.В. Мезенцева ◽  
С.С. Перцов
Keyword(s):  
Mathematical Modeling ◽  
Quantitative Analysis ◽  
Ventricular Fibrillation ◽  
Electrical Activity ◽  
Chaos Theory ◽  
Computer Experiments ◽  
Phase Portraits ◽  
Cardiac Electrical Activity ◽  
Heart Electrical Activity ◽  
Pulse Streams

Электрическая активность сердца при фибрилляции желудочков регистрируется на ЭКГ как хаотичное чередование разных по амплитуде и длительности возбуждений. Для количественного анализа этих показателей широко используются методы математического моделирования и теории хаоса. Цель исследования - использование методов математического моделирования для изучения взаимосвязи между степенью хаотичности процесса фибрилляции желудочков и количеством эктопических фокусов, функционирующих в миокарде желудочков. Электрическую активность сердца при фибрилляции желудочков моделировали суммой N-независимых импульсных потоков с различными амплитудно-частотными и фазовыми характеристиками. Степень хаотичности электрической активности сердца оценивали с помощью энтропии и фазовых портретов амплитуд фибриллярных осцилляций. Методом компьютерного моделирования рассчитывали теоретические зависимости степени хаотичности фибриллярных осцилляций от количества импульсных потоков. Результаты теоретических расчетов сопоставляли с результатами физиологических экспериментов, выполненных на крысах и собаках. Показано, что степень хаотичности фибриллярных осцилляций различна у крыс и собак и зависит от числа эктопических фокусов, функционирующих в миокарде желудочков. Для крыс были характерны двухочаговые типы моделей фибрилляции желудочков, для собак - многоочаговые (4-5 фокусов) типы моделей. Cardiac electrical activity during ventricular fibrillation shows on electrocardiogram as chaotic alternation of excitations different in amplitude and duration. Methods of mathematical modeling and the chaos theory are widely used for quantitative analysis of these irregularities. The aim of the present work was using methods of mathematical modeling to study the interrelation between the chaoticity degree of ventricular fibrillation and the number of myocardial ectopic pacemakers. Cardiac electrical activity during ventricular fibrillation was modeled as a sum of N independent pulse streams with various amplitude-frequency and phase characteristics. The chaoticity degree of heart electrical activity was estimated using entropy and phase portraits of fibrillar oscillations. Theoretical dependences between the chaoticity degree of ventricular fibrillation and the number of pulse streams were calculated using computer modeling. Results of computer experiments were compared with those of real physiological experiments on rats and dogs. The chaoticity degree of fibrillar oscillations was shown to be different in rats and dogs and dependent on the number of ectopic pacemakers functioning in the myocardium. Two-focal types of ventricular fibrillation models were characteristic of rats and multifocal (4-5 foci) types we characteristic of dogs.

Sign in / Sign up

Export Citation Format

Share Document