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.

Computer modeling of chaoticity degree of ventricular fibrillations in humans and dogs

2018 ◽  
pp. 69-73
Author(s):  
Л.В. Мезенцева
Keyword(s):  
Ventricular Fibrillation ◽  
Computer Modeling ◽  
High Frequency ◽  
Computer Experiments ◽  
Rhythmic Activity ◽  
Electric Activity ◽  
Phase Portraits ◽  
Method Of Least Squares ◽  
Study Results ◽  
Clinical Records

Для анализа фибрилляторного хаоса в настоящее время используются методы математического моделирования и теории детерминированного хаоса. Ранее нами была разработана математическая модель, позволяющая выполнять компьютерное моделирование фибрилляции желудочков в условиях различного числа источников ритмической активности (эктопических фокусов). Модель позволяет выполнять оценку количества фокусов по экспериментальным записям электрической активности сердца у животных и человека. Целью настоящего исследования является использование этой модели для изучения взаимосвязи между степенью хаотичности процесса фибрилляции желудочков и количеством эктопических фокусов, функционирующих в миокарде желудочков у человека и собак. Методом компьютерного моделирования рассчитывали теоретические зависимости степени хаотичности фибриллярных осцилляций от количества импульсных потоков. Результаты вычислительных экспериментов сравнивали с результатами экспериментов, выполненных на собаках, и клиническими записями фрагментов ЭКГ у больных с эпизодами фибрилляции желудочков. Степень хаотичности электрической активности сердца оценивали с помощью энтропии, корреляционной размерности хаоса и фазовых портретов амплитуд фибриллярных осцилляций. Далее методом наименьших квадратов решали задачу поиска вариантов моделей, наилучшим образом аппроксимирующих экспериментальные записи фибриллярных осцилляций. Это позволяло рассчитать количество эктопических фокусов и их амплитудно-частотные характеристики. Результаты исследований показали, что степень хаотичности фибриллярных осцилляций зависит от числа эктопических фокусов, функционирующих в миокарде желудочков. Расчетные значения числа эктопических фокусов у собак превышали аналогичные значения для человека. Если для собак были характерны многоочаговые типы моделей фибрилляции желудочков (4-5 фокусов), то для человека были характерны 2-3-фокусные модели. Показатели степени хаотичности фибриллярных осцилляций у собак также были выше, чем у человека. Заключение. Результаты, исследований свидетельствуют о наличии взаимосвязи между количеством независимых источников высокочастотной ритмической активности, функционирующих в миокарде желудочков, и показателями степени хаотичности фибрилляторого хаоса. For analysis of fibrillation chaos, methods of mathematical modeling and the theory of determined chaos are currently used. Earlier we have proposed a mathematical model, which allows computer modeling of ventricular fibrillation in the conditions of different number of pacemakers (ectopic foci). The model estimates the number of ectopic foci on experimental records of heart electric activity in animals and humans. The aim of this work was to use this model for studying the interrelation between degrees of ventricular fibrillation chaoticity and quantity of ectopic foci in the myocardium of humans and dogs. Methods. Theoretical dependences of fibrillation oscillation chaoticity degree on pacemaker numbers were constructed using computer modeling. Results of computer experiments were compared with those of physiological experiments on dogs and clinical records of ECG fragments from patients with episodes of ventricular fibrillation. The degree of chaoticity of heart electric activity was estimated by entropy, correlation dimension of chaos and phase portraits of fibrillary oscillation amplitudes. Further, the method of least squares was used to solve the task of finding the best model characteristics for achieving optimum correspondence between results of computed and real physiological experiments. This allowed us to calculate the number of ectopic foci and their amplitude-frequency characteristics. The results showed that the degree of chaoticity of fibrillation oscillations depended on the number of active ectopic foci in the myocardium. Calculated values for the number of ectopic foci for dogs exceeded similar values for humans. While multifocal types of models of ventricular fibrillation (4-5 foci) were characteristic of dogs, bi- and three-focal models were characteristic of humans. Characteristics of the chaoticity degree of fibrillation oscillations for dogs were also higher than similar values for humans. Conclusion. The study results showed an interrelation between the number of independent myocardial sources of high-frequency rhythmic activity and the degree of chaoticity of fibrillation chaos.

VENTRICULAR FIBRILLATION IN A SIMPLE EXCITABLE MEDIUM MODEL OF CARDIAC TISSUE

2003 ◽  
Vol 17 (29) ◽  
pp. 5645-5654 ◽  
Author(s):  
T. K. SHAJAHAN ◽  
SITABHRA SINHA ◽  
RAHUL PANDIT
Keyword(s):  
Sudden Cardiac Death ◽  
Ventricular Fibrillation ◽  
Electrical Activity ◽  
Cardiac Death ◽  
Cardiac Tissue ◽  
Excitable Medium ◽  
Electrical Activation ◽  
Preliminary Results ◽  
Cardiac Electrical Activity ◽  
Medium Model

Ventricular fibrillation (VF), the major reason behind sudden cardiac death, is turbulent cardiac electrical activity in which rapid, irregular disturbances in spatiotemporal electrical activation of heart make it incapable of any concerted pumping action. We give a brief overview of the simple Panfilov model for ventricular fibrillation, with emphasis on studies that have elucidated the nature of spiral turbulence which is the analog of VF here. The control of such turbulence is briefly touched upon. Preliminary results are presented for the effects of conduction inhomogeneity on spiral breakup, and the transition from functional to anatomical reentry as a function of the size and position of the inhomogeneity.

Vagal control of cardiac electrical activity and wall motion during ventricular fibrillation in large animals

2014 ◽  
Vol 183 ◽  
pp. 12-22 ◽  
Author(s):  
Isaac Naggar ◽  
Ko Nakase ◽  
Jason Lazar ◽  
Louis Salciccioli ◽  
Ivan Selesnick ◽  
...  
Keyword(s):  
Ventricular Fibrillation ◽  
Electrical Activity ◽  
Wall Motion ◽  
Vagal Control ◽  
Cardiac Electrical Activity ◽  
Large Animals

scholarly journals Asphyxia-activated corticocardiac signaling accelerates onset of cardiac arrest

2015 ◽  
Vol 112 (16) ◽  
pp. E2073-E2082 ◽  
Author(s):  
Duan Li ◽  
Omar S. Mabrouk ◽  
Tiecheng Liu ◽  
Fangyun Tian ◽  
Gang Xu ◽  
...  
Keyword(s):  
Cardiac Arrest ◽  
Ventricular Fibrillation ◽  
Electrical Activity ◽  
Effective Connectivity ◽  
Premature Death ◽  
Large Set ◽  
Cortical Connectivity ◽  
Heart Electrical Activity ◽  
The Brain ◽  
Sustained Increase

The mechanism by which the healthy heart and brain die rapidly in the absence of oxygen is not well understood. We performed continuous electrocardiography and electroencephalography in rats undergoing experimental asphyxia and analyzed cortical release of core neurotransmitters, changes in brain and heart electrical activity, and brain–heart connectivity. Asphyxia stimulates a robust and sustained increase of functional and effective cortical connectivity, an immediate increase in cortical release of a large set of neurotransmitters, and a delayed activation of corticocardiac functional and effective connectivity that persists until the onset of ventricular fibrillation. Blocking the brain’s autonomic outflow significantly delayed terminal ventricular fibrillation and lengthened the duration of detectable cortical activities despite the continued absence of oxygen. These results demonstrate that asphyxia activates a brainstorm, which accelerates premature death of the heart and the brain.

The Role of Computer Modeling in Electrocardiography

1990 ◽  
Vol 29 (04) ◽  
pp. 282-288 ◽  
Author(s):  
A. van Oosterom
Keyword(s):  
Electrical Activity ◽  
Computer Modeling ◽  
Body Surface ◽  
Electrical Current ◽  
The Body ◽  
Volume Conductor ◽  
Current Generator ◽  
Cardiac Electrical Activity ◽  
Source Models

AbstractThis paper introduces some levels at which the computer has been incorporated in the research into the basis of electrocardiography. The emphasis lies on the modeling of the heart as an electrical current generator and of the properties of the body as a volume conductor, both playing a major role in the shaping of the electrocardiographic waveforms recorded at the body surface. It is claimed that the Forward-Problem of electrocardiography is no longer a problem. Several source models of cardiac electrical activity are considered, one of which can be directly interpreted in terms of the underlying electrophysiology (the depolarization sequence of the ventricles). The importance of using tailored rather than textbook geometry in inverse procedures is stressed.

scholarly journals ECG Holter analysis to detect induced deconditioning on cardiac activity in bedridden volunteers

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
S Solbiati ◽  
A Paglialonga ◽  
L Costantini ◽  
E.G Caiani
Keyword(s):  
Electrical Activity ◽  
Cardiac Activity ◽  
Bed Rest ◽  
Funding Source ◽  
Healthy Male ◽  
Tukey Test ◽  
T Wave ◽  
Rehabilitation Programs ◽  
Cardiac Electrical Activity ◽  
Ethical Approval

Abstract Introduction Prolonged bed rest (BR) is an unnatural state, often related to hospitalization, chronic diseases and ageing, inducing reduced functional capacity in multiple body systems, possibly leading to cardiovascular deconditioning. We hypothesized that measuring this decline over time could represent the first step for the formulation of appropriate countermeasures or rehabilitation programs while in the hospital. Accordingly, our aim was to assess the effects of 10-day horizontal BR on cardiac electrical activity. Methods Ten healthy male volunteers (23±5 years) were enrolled in an hospital, after ethical approval and signed consent, to participate to a 10-day strict horizontal BR campaign, preceded and followed by 2 days in the facility, respectively as acclimatization and recovery. The 12-leads 24-hours Holter ECG (1000 Hz, H12+, Mortara Instrument Inc.) was acquired 1 day before BR (PRE), the 5th (BR5) and 10th day (BR10) of bedridden immobilization. From each recording, beat-to-beat RR and QTend interval series, as well as T wave amplitude (Tamp) and upslope (Tslope) were computed. Statistical analysis was applied to test changes induced by BR (ANOVA with Tukey test, p<0.05), separately for day (7:00–23:00) and night (23:00–7:00) periods. Results Daily RR and QTend duration increased during BR, with peak changes at BR5 compared to PRE (+13.3% and +3% respectively), and were still prolonged at BR10 (+12.6% and +2.6%). During the night, while RR increased (BR5:+5.3%; BR10:+1.3%), QTend was found progressively shortened (BR5: −1.6%; BR10: −2.9%). Also, day and night Tamp (BR10: −19.5%) and Tslope (BR10 day: −17.1%; night: −7.8%) were found progressively reduced with the duration of BR. Conclusion During BR, cardiac electrical activity is affected by 10-days bedridden immobilization. Noticeably, a mismatch in RR-QTend relation was visible at night, where vagal autonomic system activity is prevailing. Funding Acknowledgement Type of funding source: Other. Main funding source(s): Agenzia Spaziale Italiana (ASI)

A study of structural properties of gene network graphs for mathematical modeling of integrated mosaic gene networks

2017 ◽  
Vol 15 (02) ◽  
pp. 1650045 ◽  
Author(s):  
Olga V. Petrovskaya ◽  
Evgeny D. Petrovskiy ◽  
Inna N. Lavrik ◽  
Vladimir A. Ivanisenko
Keyword(s):  
Mathematical Modeling ◽  
Gene Regulatory Networks ◽  
Gene Networks ◽  
Gene Network ◽  
Regulatory Networks ◽  
Network Modeling ◽  
Computer Experiments ◽  
Linear Control ◽  
Expression Of Genes ◽  
Gene Regulatory

Gene network modeling is one of the widely used approaches in systems biology. It allows for the study of complex genetic systems function, including so-called mosaic gene networks, which consist of functionally interacting subnetworks. We conducted a study of a mosaic gene networks modeling method based on integration of models of gene subnetworks by linear control functionals. An automatic modeling of 10,000 synthetic mosaic gene regulatory networks was carried out using computer experiments on gene knockdowns/knockouts. Structural analysis of graphs of generated mosaic gene regulatory networks has revealed that the most important factor for building accurate integrated mathematical models, among those analyzed in the study, is data on expression of genes corresponding to the vertices with high properties of centrality.

Abstract 052: Improved Hospital Outcomes With Hypokalemia on Admission in Cardiac Arrest Survivors Treated With Therapeutic Hypothermia

2017 ◽  
Vol 10 (suppl_3) ◽  
Author(s):  
Angelo de la Rosa ◽  
Manuel Tapia ◽  
Yong Ji ◽  
Basil Saour ◽  
Mikhail Torosoff
Keyword(s):  
Logistic Regression ◽  
Cardiac Arrest ◽  
Ventricular Fibrillation ◽  
Hospital Mortality ◽  
Electrical Activity ◽  
Therapeutic Hypothermia ◽  
Multivariate Logistic Regression Analysis ◽  
Pulseless Electrical Activity ◽  
Older Age ◽  
Chi Square

Purpose: We hypothesized that advanced circulatory compromise, as manifested by acidosis and hyperkalemia should be associated with worsened clinical outcomes in cardiac arrest patients treated with therapeutic hypothermia. Methods: Results of initial admission laboratory studies, medical history, and echocardiogram in 203 consecutive cardiac arrest patients (59 females, 59+/- 15 years old) undergoing therapeutic hypothermia were reviewed. Mortality was ascertained through hospital records. ANOVA, chi-square, Kaplan-Meier, and logistic regression analyses were used. The study was approved by the institutional IRB. Results: Increased mortality was noted with older age, decreased admission pH, elevated admission lactate, lower admission hemoglobin, and pulseless electrical activity or asystole as presenting rhythms (Table). Admission hypokalemia and ventricular fibrillation/tachycardia were associated with improved hospital mortality (Table). Potassium was significantly lower in patients admitted with ventricular fibrillation/tachycardia (3.897+/-0.92) as compared to patients with asystole (4.674+/-1.377) or pulseless electrical activity (4.491+/-1.055 mEq/dL, p<0.0001). In multivariate logistic regression analysis, independent predictors of increased hospital mortality included increased admission potassium (OR 2.0, 95%CI 1.291-3.170, p=0.002)), older age (OR 1.04, 95%CI 1.007-1.071, p=0.017), admission PEA (OR 3.7, 95%CI 1.358-10.282, p=0.011 when compared to ventricular fibrillation/tachycardia) or asystole (OR 17.2, 95%CI 4.423-66.810, p<0.001 when compared to ventricular fibrillation/tachycardia); while decreased mortality was associated with higher hemoglobin (OR 0.8, 95%CI 0.665-0.997, p=0.047). Conclusions: Hyperkalemia, pulseless electrical activity, and asystole are predictive of increased hospital mortality in survivors of cardiac arrest. An association between low or low-normal potassium, observed VT-VF, and better outcomes is unexpected and may be used for prognostic purposes. More prospective investigations of mortality predictors in these critically ill patients are needed.

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