Examinando por Autor "Hyttinen, J"

Mostrando 1 - 6 de 6

Analysing Effects of Implant Dimensions on Electrocardiograph: A Modeling Approach
(2009-06-15T09:22:13Z) Väisänen, J; Requena Carrión, J; Alonso Atienza, Felipe; Rojo-Álvarez, José Luis; Hyttinen, J
Modeling offers effective means of studying the effects of implant dimensions on the measured electrocardiograph (ECG) prior to any in vivo tests, and thus provides the designer with valuable information. Finite difference (FDM) and lead field approaches combined with cardiac activation models offer straightforward and effective methods for analyzing different ECG measurement configurations. In the present study such methods are applied in studying the effects of implant dimensions on the simulated ECG which describes an ectopic beat originating from the apex. The results indicated that the change in interelectrode distance has the largest effects on the ECG. Other parameters related implant dimensions have minor effect on the ECG.
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.
Estimation of the Scope of Transvenous Lead Systems in Implantable Cardioverter Defibrillators
(2009-06-15T09:32:29Z) Requena Carrión, J; Väisänen, J; Alonso Atienza, Felipe; Rojo-Álvarez, José Luis; Hyttinen, J; García Alberola, A
The analysis of intracardiac Electrograms (EGM) recorded by transvenous lead systems in Implantable Cardioverter Defibrillators (ICD) often entails assumptions on the scope of the lead system. Based on bioelectric signal modeling and on numerical analysis, we studied quantitatively the scope of unipolar and bipolar lead configurations in ICD. We defined the scope in terms of the Mean Square Difference (MSD) between EGM generated by the whole myocardium, and EGM generated by different families of regions within the myocardium. For unipolar and bipolar lead systems, simulations showed that the smallest myocardial region involving a given value of MSD is characterized by the highest measurement sensitivity. Furthermore, the scope in the ventricles was found to be an order of magnitude smaller for bipolar leads than for unipolar leads. Bioelectric signal modeling combined with numerical analysis constitutes a powerful method to study quantitatively the scope of transvenous lead systems.
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.