Figure 1.
Models and procedure used to develop the algorithm.
(A(i)) 3D Atrial model with the different regions of the atria included in this simulation: right atrium (RA, transparent purple), right atrial appendage (RAA, beige), pectinate muscles (PM, green), cristalterminalis (CT, solid purple), sinoatrial node (SAN, red), superior vena cava (SVC), atrio-ventricular ring (AVR, grey), right pulmonary vein (RPV, blue), Bachmann’s bundle (BB, orange), left atrium (LA, light blue), left atrial appendage (LAA, yellow), inferior vena cava (IVC) and left pulmonary veins (LPV, blue). A(ii) is a snapshot of the activation of the atria at 30ms after initiation. B(i) Torso model with all the considerations used in the simulation, we can observe the position of the atria as well. B(ii) BSP produced in our simulation, corresponding to the atrial snapshot in Aii. C(i) and (ii) indicate the different stimulated points across the surface of the atria, used for focal ectopic pacing. D Positions of the electrodes placement in the torso mesh from the front (i) and from the back (ii), for the 64-lead ECG system.
Figure 2.
Positions of the atria inside the two different torso reconstructions used in this study.
A, Female torso taken from the visible human dataset [19]. B, Male torso taken from the visible human dataset [19]. The labels (i) correspond to the position based on Ho and Sanchez-Quintana [23]. The labels (ii) correspond to the position of the atria obtained from the segmentation. The different tissues accounted for in the model are illustrated in (i) and (ii); Green-Lungs, Brown-Liver, Yellow-Spinal cord, red-Ventricles, Blue-Atria, Pink-Torso.
Figure 3.
Correlation between two focal origin and the division of quadrants.
Correlation between atrial focal origin (A) and the body surface polarity (B), corresponding to ectopic pacing at the inferior vena cava (Ai) right atrial appendage (Aii). In B, both the front (left panels) and back (right panels) of the torso are shown. The quadrants on the torso and the atria are illustrated in B (i),(ii) and C. Qti indexes the quadrants of the torso B(i) and (ii), and the Qai indexes quadrants of the atria C(i) and (ii).
Table 1.
Regions of the atria included in each quadrant for the two positions inside the torso.
Figure 4.
Schematic illustration of the algorithm to identify the quadrant of atrial focal origin based on 64-lead ECG P-wave values.
Figure 5.
P-waves obtained from experimental data (blue line and grey shadow) and simulated (red line) data.
The experimental average is the average data of 8 healthy people (blue line), and the experimental range corresponds to the maximum and minimum values of these signals (grey shadow). This measurements used the same protocol as described in [14]. Both experimental and simulated P-waves were normalized for comparison.
Figure 6.
Comparison of p-waves and dipole evolution between the simulated and experimental data.
A and B Comparison of the simulated 64-lead ECG P-waves polarity (ii) to experimental data (i). In this figure, the arrangement of the P-waves is set out to match electrode placement (see Fig. 1). We observed the polarity pattern of the P-waves of the experimental and simulation, in the front (A) and back (B) part of the body. The red positive sign signifies an upright P-wave, the blue negative sign represents an inverted P-wave, and the purple positive/negative sign represents a biphasic P-wave. C Spatial (i) and amplitude (ii) temporal evolution of the dipole. The black dots and lines are the experimental data and error bar taken from [14], and the blue lines and dots are obtained from our simulation during a stimuli applied to the superior part of the sino-atrial node region. In (i) the horizontal axis is a continuous scale from the first vertical line electrodes (1–6) to the last line of electrodes (33–38), without taking in to account 31, 32, 63 and 64.