Pranav Bhagirath

171 A priori model independent inverse potential mapping: the impact of electrode positioning To evaluate the localisation error and size of the smallest visible detail, four male patients (mean age 58 ± 12 years old) with an implantedMRI-conditional DDDpacemaker system (Advisa MRI™ Surescan®, Medtronic Inc., Minneapolis, MN, USA) and a structurally normal heart were enrolled. Patient characteristics are provided in table 1 . The RV lead tip was positioned either in the RV apex (2 patients), or in the right ventricular outflow tract (RVOT) (2 patients). Table 1. Patient characteristics. Patient Age (yrs) Sex RV lead tip location Pacing indication Relevant comorbidity 1 66 M Apex Asystole Hypertension 2 42 M Apex Asystole Hemochromatosis 3 69 M RVOT AV-block - 4 54 M RVOT Chronotropic Incompetence - Written informed consent was obtained from all participants. This study complied with the declaration of Helsinki and received approval from the local ethical committee and the institutional scientific board. Body Surface Potential Mapping Three different electrode layouts were used to record data in the healthy volunteers. • Configuration I 62 electrodes surrounding the thorax. • Configuration II 62 concentrated (30 mm inter-electrode distance) electrodes directly overlaying the heart. • Configuration III 62 super-concentrated (20 mm inter-electrode distance) electrodes directly overlaying the heart. BSP were recorded using a 65-channel (62 thorax electrodes) ActiveTwo BSPM system with passive electrodes and shielded cables (BioSemi BV, Amsterdam, The Netherlands). A sampling rate of 2048 Hz was selected and every data acquisition was performed for 60 s. In thepacemaker patients, BSPwere recordedusing the62 super-concentratedelectrode configuration (configuration III). Potentials were recording during right ventricular (RV) pacing at a rate exceeding the intrinsic rate with at least 15 beats/min (paced AV-delay 70 ms).