Examinando por Autor "Malmivuo, J"

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Analysis of the Scope of Unipolar and Bipolar Electrograms in Implantable Cardioverter Defibrillators
(2009-07-23T10:51:41Z) Requena Carrión, Jesús; Väisänen, J; Hyttinen, J; Rojo-Álvarez, José Luis; Alonso Atienza, Felipe; Malmivuo, J
Contribution of the Left Anterior Myocardium to the Body Surface Potentials in Case of Apical Ectopic Beat
(2009-06-15T09:36:55Z) Väisänen, J; Requena Carrión, J; Alonso Atienza, Felipe; Rojo-Álvarez, José Luis; Malmivuo, J; Hyttinen, J
The present paper describes a study where effects of anterior myocardium on body surface potentials were investigated. The study combines numerical lead field analysis combined with cardiac automata model. Electric fields are calculated with finite difference method in a 3-D model of male thorax. The cardiac activation applied in the study is an ectopic beat originating in the apex. The correlations and mean differences between signal generated by anterior segments of left ventricle and signal generated by both ventricles were analysed for 117 leads. The results show that there are leads which have high correlation (>0.9) with low the relative mean difference (<0.2) between the signals generated by anterior segments and signals generated by whole ventricles. These electrode locations would be optimal to monitor the activation of anterior segments when ectopic beats originate in apex.
Contributions of the 12 Segments of Left Ventricular Myocardium to the Body Surface Potentials
(2009-07-23T11:39:20Z) Väisänen, J; Requena Carrión, Jesús; Alonso Atienza, Felipe; Hyttinen, J; Rojo-Álvarez, José Luis; Malmivuo, J
Experimental and inverse approaches have been applied in studying the contributions of different parts of the myocardium to the ECG measurements. Also optimal electrode locations for different clinical purposes have been studied by applying body surface maps. It is valuable to know where the measured ECG is actually generated. Thus the measurements can be designed to be most optimal to measure certain myocardial sources. Here we assess the contributions of 12 left ventricular segments to the potentials of 117 surface leads. The study is based on the numerical lead field analysis combined with the cardiac activation modeling. We analyzed the contributions of the signals generated by different segments to the total signal generated by the left ventricle. It was found that anterior segments have high contributions to the leads on the lower left thorax and inferior segments on the leads on the lower left back. These results were expected based on the previous clinical studies.
Numerical Analysis of the Resolution of Surface Electrocardiographic Lead Systems
(2009-07-23T11:45:29Z) Requena Carrión, Jesús; Väisänen, J; Rojo-Álvarez, José Luis; Hyttinen, J; Alonso Atienza, Felipe; Malmivuo, J
Non-invasive electrocardiographic (ECG) techniques for assessing the electrical activity of selected regions within the cardiac muscle can benefit from suitable positioning of surface electrodes. This positioning is usually guided heuristically and complemented by clinical and experimental studies, but there is a lack of general methods to characterize quantitatively the ability of a given electrode configuration to focus on selected regions of the heart. In this study we explore an approach to the characterization of the resolution of surface ECG systems based on the concept of Resolution Mass (RM). By integrating bioelectric signal modeling and numerical methods, we explore, in an application example, the location and size of the RM for a multielectrode ECG system. The concept of RM combined with bioelectric signal modeling and numerical methods constitutes a powerful tool to investigate the resolution properties of surface ECG systems.