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PubMed2005

Lead field computation for the electrocardiographic inverse problem--finite elements versus boundary elements.

In order to be able to solve the inverse problem of electrocardiography, the lead field matrix (transfer matrix) has to be calculated. The two methods applied for computing this matrix, which are compared in this study, are the boundary element method (BEM) and the finite element method (FEM). The performance of both methods using a spherical model was investigated. For a comparable discretization level, the BEM yields smaller relative errors compared to analytical solutions. The BEM needs less computation time, but a larger amount of memory. Inversely calculated myocardial activation times using either the FEM or BEM computed lead field matrices give similar activation time patterns. The FEM, however, is also capable of considering anisotropic conductivities. This property might have an impact for future development, when also individual myocardial fiber architecture can be considered in the inverse formulation.

Anisotropy↗

PubMed2004

Ventricular surface activation time imaging from electrocardiogram mapping data.

Non-invasive imaging of cardiac electrophysiology provides a non-invasive way of obtaining information about electrical excitation. An iterative algorithm based on a general regularisation scheme for non-linear, ill-posed problems in Hilbert scales was applied to the electrocardiographic inverse problem, imaging the ventricular surface activation time (AT) map. This method was applied to electrocardiographic data from a 31-year-old healthy volunteer and a 24-year-old patient suffering from a Wolff-Parkinson-White (WPW) syndrome. The objective was to evaluate non-invasive AT imaging of an autonomous sinus rhythm and to quantify the localisation error of non-invasive AT imaging by localising the accessory pathway of the WPW syndrome and a pacing site for left ventricle pacing. The distances between the invasive and non-invasive localisation of the pacing site and the accessory pathway were 8 mm and 5 mm. The clinical case presented, shows that this non-invasive AT imaging approach may enable the reconstruction of single focal events with sufficient accuracy for potential clinical application.

Adult↗