ACCURACY OF SINGLE-DIPOLE INVERSE SOLUTION WHEN LOCALIZING VENTRICULAR PREEXCITATION SITES - SIMULATION STUDY

Different factors are investigated that may affect the accuracy of an inverse solution that uses a single-dipole equivalent generator, in a standardised inhomogeneous torso model, when localising the pre-excita tion sites. An anatomical model of the human ventricular myocardium is used to simulate body surface potential maps (BSPMs) and magnetic fie ld maps (MFMs) for 35 pre-excitation sites positioned on the epicardia l surface along the atrioventricular ring. The sites of pre-excitation activity are estimated by the single-dipole method, and the measure f or the accuracy of the localisation is the localisation error, defined as the distance between the location of the best-fitting single dipol e and the actual site of pre-excitation in the ventricular model. The findings indicate that, when the electrical properties of the volume c onductor and lead positions are precisely known and the 'measurement' noise is added to the simulated BSPMs and MFMs, the single-dipole meth od optimally localises the pre-excitation activity 20 ms after the ons et of pre-excitation, within 0.71+/-0.28 cm and 0.65+/-0.30 cm using B SPMs and MFMs, respectively. When the standard torso model is used to localise the sites of onset of the pre-excitation sequence initiated i n four individualised torso models, the maximum errors are as high as 2.6-3.0 cm (even though the average error, for both the BSPM and MFM l ocalisations, remains within the 1.0-1.5 cm range). In spite of these shortcomings, it is thought that single-dipole localisations can be us eful for non-invasive pre-interventional planning.