Wavelet Denoising for Multi-lead High Resolution ECG Signals

Abstract. The aim of this study was to investigate the application of wavelet denoising in noise reduction of multichannel high resolution ECG signals. In particular, the influence of the selection of wavelet function and the choice of decomposition level on efficiency of denoising process were considered and whole procedures of noise reduction were implemented in MatLab environment. The Fast Wavelet Transform was use. The advantage of used denoising method is noise level decreasing in ECG signals, in which noise reduction by averaging has limited application, i.e. in case of arrhythmia, or in presence of extrasystols

Optical methods of molecular imaging

Obrazowanie molekularne jest szybko rozwijającą się dziedziną badań w zakresie biotechnologii i inżynierii biomedycznej. W artykule przedstawiono przegląd technik stosowanych w obrazowaniu molekularnym, wykorzystujących metody medycyny nuklearnej oraz optyczne techniki oparte na analizie promieniowania fluorescencyjnego. W szczególności opisano metody optyczne obrazowania molekularnego stosowane w skali mikroskopowej (mikroskopia konfokalna, obrazowanie czasu relaksacji fluorescencyjnej, transfer energii Foerstera) oraz wykorzystywane w badaniach na zwierzętach doświadczalnych. Omówiono także potencjalne wykorzystanie technik optycznych w badaniach dużych objętości tkanek.Molecular imaging (MI) is a rapidly emerging field of biomedical, biotechnological and engineering research. This study provides a brief review of the state-of-the-art techniques and methods of MI based on nuclear physics and fluorescent agents. Special attention will be focused on optical methods of MI applied in microscopic scale (multiphoton confocal microscopy, fluorescence lifetime imaging, Forster energy transfer) and in experimental animals. Potential application of MI in large tissue volumes will be also discussed

Principles and practice of the laser-Doppler perfusion technique

This paper reviews the development and use of laser‐Doppler perfusion monitors and imagers over the past two decades. The enormous interest in microvascular blood perfusion coupled with the ‘ease of use’ of the technique has led to [TeX:] 1500+ publications citing its use. However, useful results can only be achieved with an understanding of the basic principles of the instrumentation and its application in the various clinical disciplines. The basic theoretical background is explored and definitions of blood perfusion and laser‐Doppler perfusion are established. The calibration method is then described together with potential routes to standardisation. A guide to the limitations in application of the technique gives the user a clear indication of what can be achieved in new studies as well as possible inadequacy in some published investigations

Lessons learned from 2 patients with multidrug-resistant HIV-1 infection successfully treated with a darunavir-containing antiretroviral treatment regimen

The authors describe 2 patients with life-threatening multidrug-resistant HIV-1 infection who responded very well to a treatment regimen containing darunavir and enfuvirtide. They discuss the availability of several new treatment options such as darunavir, etravirine, integrase, and CCR5 inhibitors for patients with multidrug-resistant viruses

The roles of mid-myocardial and epicardial cells in T-wave alternans development : a simulation study

Background: The occurrence of T-wave alternans in electrocardiographic signals was recently linked to susceptibility to ventricular arrhythmias and sudden cardiac death. Thus, by detecting and comprehending the origins of T-wave alternans, it might be possible to prevent such events. Results: Here, we simulated T-wave alternans in a computer-generated human heart model by modulating the action potential duration and amplitude during the first part of the repolarization phase. We hypothesized that changes in the intracardiac alternans patterns of action potential properties would differentially influence T-wave alternans measurements at the body surface. Specifically, changes were simulated globally in the whole left and right ventricles to simulate concordant T-wave alternans, and locally in selected regions to simulate discordant and regional discordant, hereinafter referred to as “regional”, T-wave alternans. Body surface potential maps and 12-lead electrocardiographic signals were then computed. In depth discrimination, the influence of epicardial layers on T-wave alternans development was significantly higher than that of mid-myocardial cells. Meanwhile, spatial discrimination revealed that discordant and regional action potential property changes had a higher influence on T-wave alternans amplitude than concordant changes. Notably, varying T-wave alternans sources yielded distinct body surface potential map patterns for T-wave alternans amplitude, which can be used for location of regions within hearts exhibiting impaired repolarization. The highest ability for T-wave alternans detection was achieved in lead V1. Ultimately, we proposed new parameters Vector Magnitude Alternans and Vector Angle Alternans, with higher ability for T-wave alternans detection when using multi-lead electrocardiographic signals processing than for single leads. Finally, QT alternans was found to be associated with the process of T-wave alternans generation. Conclusions: The distributions of the body surface T-wave alternans amplitude have been shown to have unique patterns depending on the type of alternans (concordant, discordant or regional) and the location of the disturbance in the heart. The influence of epicardial cells on T-wave alternans development is significantly higher than that of mid-myocardial cells, among which the sub-endocardial layer exerted the highest influence. QT interval alternans is identified as a phenomenon that correlate with T-wave alternans