Search results for "Atrial"

CATHAR : CATHeter for ARRhythmias : determination of depth of burned biological tissues with microwave

2015

Cardiac arrhythmia substrates may be treated by intracardiac ablations which consist in burning specific atrial or ventricular endocardial substrates. Created lesions which are not transmural may be responsible for arrhythmia recurrences. To date, the depth of the lesion inside the endocardium can't be assessed accurately during the procedures. Our experimental work has focused on microwave characterization of biological tissues (in vitro) to assess the burn depth. Using a reflection technique with a coaxial probe in contact with tissues, measurements were made over a wide frequency range (100 MHz to 6 GHz). The measured reflection coefficient is known to be directly related to the dielectr…

Atrial natriuretic peptide and CD34 overexpression in human idiopathic dilated cardiomyopathies.

2007

Idiopathic dilated cardiomyopathy (IDCM) is a primary myocardial disease of unknown cause characterized by ventricular chamber enlargement with impaired contractile function. In familial forms of IDCM, mutations of genes coding for cytoskeletal proteins related to force transmission, such as dystrophin, cardiac actin, desmin, and delta-sarcoglycan, have been identified. Here, we report the data of a retrospective investigation carried out to evaluate the expression of atrial natriuretic peptide (ANP), CD34, troponin T and nestin in the myocardium of patients affected with IDCM. Formalin-fixed and paraffin-embedded consecutive tissue sections from the ventricular wall of 10 human normal hear…

Detailed Anatomical and Electrophysiological Models of Human Atria and Torso for the Simulation of Atrial Activation

2015

Atrial arrhythmias, and specifically atrial fibrillation (AF), induce rapid and irregular activation patterns that appear on the torso surface as abnormal P-waves in electrocardiograms and body surface potential maps (BSPM). In recent years both P-waves and the BSPM have been used to identify the mechanisms underlying AF, such as localizing ectopic foci or high-frequency rotors. However, the relationship between the activation of the different areas of the atria and the characteristics of the BSPM and P-wave signals are still far from being completely understood. In this work we developed a multi-scale framework, which combines a highly-detailed 3D atrial model and a torso model to study th…

P4020Use of novel oral anticoagulants in patients with atrial fibrillation and moderate to severe renal dysfunction: findings from a prospective nati…

2017

Isolation of the left atrial surface from cardiac multi-detector CT images based on marker controlled watershed segmentation

2006

The delineation of left atrium (LA) and pulmonary veins (PVs) anatomy from high resolution images holds importance for atrial fibrillation (AF) investigation and treatment. In this study, a semiautomatic segmentation procedure for LA and PVs inner surface from contrast enhanced CT data was developed. The procedure consists of a three dimensional marker controlled watershed segmentation applied to the external morphological gradient, followed by variable threshold surface extraction from the original intensity image. A preliminary anisotropic non-linear filtering was implemented to improve the S/N ratio of CT images. The performance of segmentation was evaluated on cardiac CT scans of 12 AF …

Localization of the atrial natriuretic factor in the human inferior turbinates. An immunohistochemical study

2003

In man, the architecture of the turbinates is able to modify some of the physiochemical characteristics of the air inhaled. These modifications depend on the nervous system and on the action of neurotransmitters such as vasoactive intestinal peptide. Substance P, calcitonin gene-related peptide and other neuropeptides. As atrial natriuretic factor has been detected in the trachea and lung, the present immunohistochemical study was carried out to establish the presence and localisation of the atrial natriuretic factor on the inferior turbinates of the human being. The findings show atrial natriuretic factor to be present in the serous epithelial cells and in some cells of the tonaca propria …

Hemorrhage in patients under oral anticoagulation for atrial fibrillation. The other side of the coin

2019

Abstract Introduction and objectives Oral anticoagulation therapy is prescribed to most patients with atrial fibrillation. The main limitation of anticoagulant treatment is the occurrence of bleeding episodes. We sought to assess the type of hemorrhages and mortality in patients anticoagulated for nonvalvular atrial fibrillation. Methods Observational retrospective study analyzing 2 081 138 hospitalization reports from 2014 corresponding to 151 hospitals of the Spanish National Health System. Patients were selected with the diagnosis of hemorrhage, nonvalvular atrial fibrillation, and oral anticoagulation. Results A total of 5783 hospitalizations were analyzed. Most hemorrhages were digesti…

Propagation pattern analysis during atrial fibrillation based on sparse modeling.

2012

In this study, sparse modeling is introduced for the estimation of propagation patterns in intracardiac atrial fibrillation (AF) signals. The estimation is based on the partial directed coherence function, derived from fitting a multivariate autoregressive model to the observed signal using least-squares (LS) estimation. The propagation pattern analysis incorporates prior information on sparse coupling as well as the distance between the recording sites. Two optimization methods are employed for estimation of the model parameters, namely, the adaptive group least absolute selection and shrinkage operator (aLASSO), and a novel method named the distance-adaptive group LASSO (dLASSO). Using si…

Propagation pattern analysis during atrial fibrillation based on the adaptive group LASSO.

2012

The present study introduces sparse modeling for the estimation of propagation patterns in intracardiac atrial fibrillation (AF) signals. The estimation is based on the partial directed coherence (PDC) function, derived from fitting a multivariate autoregressive model to the observed signals. A sparse optimization method is proposed for estimation of the model parameters, namely, the adaptive group least absolute selection and shrinkage operator (aLASSO). In simulations aLASSO was found superior to the commonly used least-squares (LS) estimation with respect to estimation performance. The normalized error between the true and estimated model parameters dropped from 0.200.04 for LS estimatio…

Secondary Stroke Prevention in Polish Adults: Results from the LIPIDOGRAM2015 Study

2021

Background: The purpose of the study was to evaluate secondary stroke prevention in Poland and its association with sociodemographic factors, place of residence, and concomitant cardiovascular risk factors. Material and methods: From all patients in LIPIDOGRAM2015 Study (n = 13,724), 268 subjects had a history of ischaemic stroke and were included. Results: 165 subjects (61.6%) used at least one preventive medication. Oral antiplatelet and anticoagulation agents were used by 116 (43.3%) and 70 (26.1%) patients, respectively. Only 157 (58.6%) participants used lipid-lowering drugs, and 205 (76.5%) were treated with antihypertensive drugs. Coronary heart disease (CHD) and dyslipidaemia were a…