Search results for "frequency [modulation]"

Simplified Electrophysiology Modeling Framework to Assess Ventricular Arrhythmia Risk in Infarcted Patients

2021

Patients that have suffered a myocardial infarction are at lifetime high risk for sudden cardiac death (SCD). Personalized 3D computational modeling and simulation can help to find non-invasively arrhythmogenic features of patients’ infarcts, and to provide additional information for stratification and planning of radiofrequency ablation (RFA). Currently, multiscale biophysical models require high computational resources and long simulations times, which make them impractical for clinical environments. In this paper, we develop a phenomenological solver based on cellular automata to simulate cardiac electrophysiology, with results comparable to those of biophysical models. The solver can ru…

A hybrid stimulation strategy for suppression of spiral waves in cardiac tissue

2011

International audience; Atrial fibrillation (AF) is the most common cardiac arrhythmia whose mechanisms are thought to be mainly due to the self perpetuation of spiral waves (SW). To date, available treatment strategies (antiarrhythmic drugs, radiofrequency ablation of the substrate, electrical cardioversion) to restore and to maintain a normal sinus rhythm have limitations and are associated with AF recurrences. The aim of this study was to assess a way of suppressing SW by applying multifocal electrical stimulations in a simulated cardiac tissue using a 2D FitzHugh-Nagumo model specially convenient for AF investigations. We identified stimulation parameters for successful termination of S…

Changes in the Spectral Characteristics of Ventricular Fibrillation in Lesions Produced by Radiofrequency Ablation. An Experimental Study

2008

INTRODUCTION AND OBJECTIVES Although electro- physiological databases contain information about changes in the time domain in lesions produced by radiofrequency ablation, very few data on changes in the frequency domain are available. The aim of this study was to investigate changes in the spectral characteristics of ventricular fibrillation in zones with radiofrequency lesions. METHODS Recordings of ventricular fibrillation were obtained in 11 isolated perfused rabbit heart preparations using a multiple epicardial electrode located on the left ventricular free wall. Spectral parameters derived by Fourier analysis before and after the creation of transmural radiofrequency lesions were compa…

Personalized Cardiac Computational Models: From Clinical Data to Simulation of Infarct-Related Ventricular Tachycardia.

2019

In the chronic stage of myocardial infarction, a significant number of patients develop life-threatening ventricular tachycardias (VT) due to the arrhythmogenic nature of the remodeled myocardium. Radiofrequency ablation (RFA) is a common procedure to isolate reentry pathways across the infarct scar that are responsible for VT. Unfortunately, this strategy show relatively low success rates; up to 50% of patients experience recurrent VT after the procedure. In the last decade, intensive research in the field of computational cardiac electrophysiology (EP) has demonstrated the ability of three-dimensional (3D) cardiac computational models to perform in-silico EP studies. However, the personal…

Novel Application of Pulsed Radiofrequency Energy Device (PEAK Plasmablade) in Neurosurgical Reconstructive Surgery.

2018

In vitro comparison of platinum-iridium and gold tip electrodes: lesion depth in 4 mm, 8 mm, and irrigated-tip radiofrequency ablation catheters

2009

Aims We compared a newly developed irrigated gold tip electrode ablation catheter and a gold tip 4 and 8 mm catheter with the corresponding platinum–iridium (Pt) tip catheters in an in vitro setting. Methods and results In a flow chamber simulating physiological flow conditions, radiofrequency catheter ablation was performed on tissue samples of porcine endomyocardium and liver. Lesion depth, energy and temperature delivery, and popping frequency were determined. Two hundred and fifty-three ablations were conducted. Four and eight millimetre, gold tip electrode catheters produced significantly deeper lesions compared with the Pt tip electrode (liver 4 mm: 4.67 ± 1.7 vs. 2.9 ± 1.0 mm, P < 0.…

The independent and combined influence of schizophrenia polygenic risk score and heavy cannabis use on risk for psychotic disorder: A case-control an…

2019

Background: Some recent studies have challenged the direction of causality for the association between cannabis use and psychotic disorder, suggesting that cannabis use initiation is explained by common genetic variants associated with risk of schizophrenia. We used data from the European Union Gene-Environment Interaction consortium (EUGEI) case-control study to test for the independent and combined effect of heavy cannabis use, and of Schizophrenia Polygenic risk score (SZ PRS), on risk for psychotic disorder. Methods: Genome-wide data were obtained from 492 first episode psychosis patients (FEPp) and from 787 controls of European Ancestry, and used to generate SZ PRS from the summary res…

Time and frequency domain analysis of long-term heart rate variability in an experimental model of diet-induced metabolic syndrome

2021

Abstract Background Metabolic syndrome (MetS) is defined as the set of at least three of the following conditions: central obesity, elevation of triglycerides, decreased in high-density lipoproteins, systemic hypertension and glucose intolerance. MetS is linked with a high prevalence of cardiovascular disease, including sudden cardiac death and atrial arrhythmias, which may be a consequence of changes related to the structure, function and autonomic control of the heart. One of the underlying mechanisms responsible could be the alteration of sinus node automaticity. Heart rate variability (HRV) analysis is a useful non-invasive tool for evaluating alterations in neural control of cardiac au…

High-Frequency Oscillatory Ventilation In Patients With Chronic Obstructive Pulmonary Disease

2011

A hidden type of internet addiction? Intense and addictive use of social networking sites in adolescents

2016

Internet Gaming Disorder has been included as a preliminary diagnosis in DSM-5. The question remains, if there are additional internet activities related to addictive use. Especially, use of social networking sites has been discussed to be related to excessive use, but only few empirical studies are available. We wanted to explore, if use of social networking sites is related to addiction symptoms and psychosocial distress and which variables (demography, personality) predict addictive use. A representative sample of n?=?9173 adolescents (12-19 years) was enrolled. Self-report questionnaires assessed demography, frequency of social networking sites use, internet addiction, personality, and …