0000000000261802
AUTHOR
J. Millet
Flat panel displays for medical monitoring systems
Flat panel displays are ideal for demanding hospital and clinic applications like vital sign monitoring and bedside administration. They take up much less space than conventional monitors (CRT based) and can be wall-mounted, cart-mounted or used on a desk stand. User friendly interface demands easy to use input device, rotary position encoders and touch screen panels offers simplicity replacing bulky keyboards. This article will present an overview about today's medical monitoring systems tendencies, describing as an example, a custom medical monitoring module developed to be integrated in an assisted ventilation system.
Adapting power consumption to performance requirements in a MSP430 microcontroller
Microcontroller based low power systems using batteries must run at low clock frequencies with short activity periods to extend battery life. These constraints reduce the microcontroller computational capabilities and limit the complexity of algorithms that can be used. New microcontroller architectures, as the Texas Instruments MSP430 family, allow to adapt power consumption to application performance requirements combining several low power modes with the capability of switching the clock frequency dynamically. A complete characterization of power consumption vs. performance has been obtained for the MSP430. A method to determine the range of clock frequencies that meets a consumption and…
Bioelectric model of atrial fibrillation: Applicability of blind source separation techniques for atrial activity estimation in atrial fibrillation episodes
In this contribution, we present the theoretical justification that give support to the suitability of blind signal separation (BSS) techniques for the estimation of the atrial activity (AA) present in ECGs of persistent atrial fibrillation (AF). The application of BSS methods to this problem needs the fulfillment of several conditions regarding AA, ventricular activity (VA) and the fashion in which both activities arise on the body surface, that will be justified along the paper. To empirically validate the model, an ICA method is applied to 10 real 12-lead recordings of AF. The identification of AA is put forward based on kurtosis and spectral analysis. The kurtosis value of the estimated…
Wavelet variance differences in atrial fibrillation during anaesthetic effect
Effect of anaesthetic agents in restoration rhythm procedures during atrial fibrillation (AF) has not been fully investigated. We evaluated the effects of a widely used anaesthetic agent (propofol) in the fibrillation patterns. Intra-atrial recordings belong to 18 patients diagnosed with AF were analyzed ldquobeforerdquo (baseline) and ldquoduringrdquo anaesthetic infusion. The goal of this study is to characterize the variation in atrial properties along the atria in both states. The wavelet variance decomposes the variance of a time series on a scale by scale basis and hence has considerable appeal when physical phenomena are analyzed in terms of variations operating over a range of diffe…
Analysis of inter-atrium differences in paroxysmal and persistent atrial fibrillation using principal component analysis
The pathophysiological mechanisms of atrial fibrillation (AF) are not entirely clear yet, and there is no full explanation for the development and evolution of the arrhythmia. The goal of this study is to find inter-atrium differences in electrophysiological behavior between persistent and paroxysmal AF. The database analyzed contains intra-cardiac records from 14 patients with paroxysmal AF and 10 with persistent AF. Dominant frequency and sample entropy measurements showed that in the paroxysmal group there was a left-to-right gradient. These differences were enhanced after the extraction of the main components with principal component analysis. These findings may be interpreted as a poss…
A novel multielectrode for epicardial recording with temperature control based in Peltier cells
Electrophysiological parameters of the myocardium are influenced by temperature. Working with experimental models of isolated heart, the analysis of modulating effect exerted by local changes of temperature can provide some information about the mechanisms of certain arrhythmias and their electrophysiological bases, such as ventricular fibrillation. Conventional multiple electrodes do not seem to be appropriate, being necessary the development of specific devices. The design and implementation of a device adapted to these requirements is presented in this paper. This is a multi-electrode able to reproduce located and controlled conditions of hypothermia and hyperthermia, in a determined are…
[Myocardial echocardiography with intracoronary injection of contrast in post-infarction patients. Implications and comparison with angiography and magnetic resonance imaging].
We analyzed the safety and feasibility of myocardial echocardiography with intracoronary injection of contrast, its effect on left ventricular remodeling and systolic function, and its relationship with angiography and magnetic resonance imaging (MRI) for the evaluation of post-infarction coronary microcirculation.Thirty patients with a first ST-elevation myocardial infarction and a patent infarct-related artery were studied. Mean perfusion score of the infarcted area was analyzed with myocardial echocardiography. TIMI and Blush grades (angiography) were determined. Mean perfusion score (MRI-perfusion), end-diastolic volume index and ejection fraction were determined with MRI. At 6 months a…
Poincaré surface profile. Novel non-invasive method to detect preferential ventricular response during atrial fibrillation
The strategy of rate control during atrial fibrillation (AF) essentially deals with efforts to utilize and adjust the filtering properties of the atrioventricular (AV) node, allowing AF to continue and ensure that ventricular rate is controlled. In this work, a new tool based on the 3D Poincare plots is developed for the characterization of the ventricular response (VR) and the clinical evaluation of rate control therapies. Mechanisms underlying atrioventricular conduction during AF remain unclear. The role of the dual pathway AV nodal electrophysiology and the effects of the AV node modifications are still being an incognita. RR interval clusters exhibiting harmonic behaviour have been qua…
Comparative analysis in terms of computational cost for different discrimination algorithms in implantable defibrillators
Implantable defibrillators (ICDs) use very low computational cost criteria (rate, stability and onset) offering good sensitivity for arrhythmia detection. Although, the specificity of these combined criteria decreases in difficult arrhythmia discrimination as in case of discrimination between ventricular tachycardia (VT) and supraventricular tachycardia (SVT). Several morphological published algorithms enhance arrhythmia discrimination but most algorithms are developed in personal computers and cannot be used in ICDs because of computational cost requirements compared with limited ICD capabilities. A general method to determine the possibility of ICD implementation for a discrimination algo…
Estudio de perfusión en pacientes postinfarto mediante ecografía miocárdica con inyección de contraste intracoronario. Implicaciones y relación con la angiografía y la resonancia magnética
38 Objetivos. Analizamos la aplicabilidad y seguridad de la ecografia miocardica con inyeccion intracoronaria de contraste, su papel en la remodelacion ventricular y en la funcion sistolica, asi como su relacion con la angiografia y la resonancia magnetica para valorar la microcirculacion coronaria postinfarto. Pacientes y metodo. Se estudio a 30 pacientes con un primer infarto de miocardio con elevacion del segmento ST y arteria responsable abierta. Con inyeccion intracoronaria de contraste se determino la puntuacion media de perfusion en la zona infartada. Mediante angiografia se cuantificaron los grados TIMI y Blush. Se utilizo la resonancia magnetica para determinar la puntuacion media …