Inverse Solution Mapping of Epicardial Potentials

Abstract

Background-Catheter ablation of ventricular tachycardia (VT) is still one of the most challenging procedures in cardiac electrophysiology, limited, in part, by unmappable arrhythmias that are nonsustained or poorly tolerated. Calculation of the inverse solution from body surface potential mapping (sometimes known as ECG imaging) has shown tremendous promise and can rapidly map these arrhythmias, but we lack quantitative assessment of its accuracy in humans. We compared inverse solution mapping with computed tomography-registered electroanatomic epicardial contact catheter mapping to study the resolution of this technique, the influence of myocardial scar, and the ability to map VT. Methods and Results-For 4 patients undergoing epicardial catheter mapping and ablation of VT, 120-lead body surface potential mappings were obtained during implantable defibrillator pacing, catheter pacing from 79 epicardial sites, and induced VT. Inverse epicardial electrograms computed using individualized torso/epicardial surface geometries extracted from computed tomography images were compared with registered electroanatomic contact maps. The distance between estimated and actual epicardial pacing sites was 13±9 mm over normal myocardium with no stimulus-QRS delay but increased significantly over scar (P=0.013) or was close to scar (P=0.014). Contact maps during right ventricular pacing correlated closely to inverse solution isochrones. Maps of inverse epicardial potentials during 6 different induced VTs indicated areas of earliest activation, which correlated closely with clinically identified VT exit sites for 2 epicardial VTs. Conclusions-Inverse solution maps can identify sites of epicardial pacing with good accuracy, which diminishes over myocardial scar or over slowly conducting tissue. This approach can also identify epicardial VT exit sites and ventricular activation sequences. (Circ Arrhythm Electrophysiol. 2012;5:1001-1009.)

Noninvasive epicardial and endocardial electrocardiographic imaging of scar-related ventricular tachycardia

“…Patients were enrolled from those undergoing epicardial and endocardial catheter mapping and ablation of VT. As detailed in our previous study [20], in a protocol approved by the institutional Research Ethics Board, axial CT (0.8–3 mm, Siemens Sonata, Erlangen, Germany) was performed within 24 hours before the procedure. Body surface electrodes (Foxmed, Idstein, Germany) were applied immediately before the clinical procedure according to the previously published Dalhousie protocol [22].…”

“…Although 3D scar anatomy can be reliably delineated by imaging modalities such as delayed contrast-enhanced MRI [18], ECG-imaging also has the unique ability to reveal the arrhythmia dynamics of VT. In the latter context, some studies have reported the use of ECG-imaging in reconstructing the activation isochrones and localizing the origin of VT [19], [20]. These initial studies focused on VT mapping on only the epicardium of the heart and the reentry circuit was studied in the form of a static map of activation sequence.…”

Spatially Coherent Activation Maps for Electrocardiographic Imaging

“…Although invasive epicardial mapping has already been used as a reference to evaluate ECGi [25], [26], this article presents the largest series ever published, which is an important step in in-vivo validation of the technique.…”

Patient-specific flexible and stretchable devices for cardiac diagnostics and therapy

“…In 1999 Rudy introduced an algorithm for estimating the epicardial activation from body surface electrograms using inverse problem based calculations (Rudy, 1999). Since then, several groups have continued this line of work and expanded the application to include mapping of repolarization and some therapeutic interventions (Cochet et al, 2014; Sapp et al, 2012; Zhang et al, 2013a). This technique is computationally expensive and requires CT images for the precise location of the body surface electrodes.…”