Abstract
BackgroundWith the advent of magnetic resonance imaging (MRI) conditional pacemaker systems, the possibility of performing MRI in pacemaker patients has been introduced. Besides for the detailed evaluation of atrial and ventricular volumes and function, MRI can be used in combination with body surface potential mapping (BSPM) in a non-invasive inverse potential mapping (IPM) strategy. In non-invasive IPM, epicardial potentials are reconstructed from recorded body surface potentials (BSP). In order to investigate whether an IPM method with a limited number of electrodes could be used for the purpose of non-invasive focus localization, it was applied in patients with implanted pacing devices. Ventricular paced beats were used to simulate ventricular ectopic foci.MethodsTen patients with an MRI-conditional pacemaker system and a structurally normal heart were studied. Patient-specific 3D thorax volume models were reconstructed from the MRI images. BSP were recorded during ventricular pacing. Epicardial potentials were inversely calculated from the BSP. The site of epicardial breakthrough was compared to the position of the ventricular lead tip on MRI and the distance between these points was determined.ResultsFor all patients, the site of earliest epicardial depolarization could be identified. When the tip of the pacing lead was implanted in vicinity to the epicardium, i.e. right ventricular (RV) apex or RV outflow tract, the distance between lead tip position and epicardial breakthrough was 6.0 ± 1.9 mm.ConclusionsIn conclusion, the combined MRI and IPM method is clinically applicable and can identify sites of earliest depolarization with a clinically useful accuracy.Electronic supplementary materialThe online version of this article (doi:10.1007/s10840-015-0054-9) contains supplementary material, which is available to authorized users.
Highlights
Besides for the detailed evaluation of atrial and ventricular volumes and function, magnetic resonance imaging (MRI) can be used in combination with body surface potential mapping (BSPM) in a non-invasive inverse potential mapping (IPM) strategy
Inverse potential mapping was performed in ten male patients with an implanted MRIconditional DDD pacemaker system (Advisa MRITM Surescan®, Medtronic Inc., Minneapolis, MN, USA) and a structurally normal heart
body surface potentials (BSP) were recorded in supine position at a sampling rate of 2048 Hz for 10 s during right ventricular (RV) pacing at a rate exceeding the intrinsic rate with at least 15 beats per minute
Summary
2.2 Body surface potential mappingInvasive electrophysiological procedures are often complicated by considerable fluoroscopic time, non-inducibility of the arrhythmia or hemodynamic instability of the patient [1]. Pre-procedural and non-invasive localization of arrhythmogenic foci may improve the clinical outcome and reduce the duration of the invasive procedures [2] To this intent, over the last decade various non-invasive mapping strategies, e.g. electrocardiographic imaging (ECGI) [3], non-invasive imaging of cardiac electrophysiology (NICE) [4] and AMICARD [5] have been introduced. Despite numerous reports on the possible advantages of non-invasive mapping, this approach has not yet advanced into daily clinical practice as a routine tool. This is either due to the impracticability associated with the use of up to 254 torso electrodes or to the limited data available from in vivo studies with respect to the accuracy and validity of the estimated epicardial potentials or intramural activation times. Ventricular paced beats were used to simulate ventricular ectopic foci
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