Ability of magnetocardiography to detect regional dominant frequencies of atrial fibrillation

Abstract

BackgroundLead V1 on electrocardiography (ECG) can detect the dominant frequency (DF) of atrial fibrillation (AF) in the right atrium (RA). Paroxysmal AF is characterized by a frequency gradient from the left atrium (LA) to the right atrium (RA). We examined the ability of magnetocardiography (MCG) to detect regional DFs in both the atria.MethodsStudy subjects comprised 18 consecutive patients referred for catheter ablation of persistent AF. An MCG system with 64 magnetic sensors was used to perform MCG in the frontal, lateral, and back planes prior to the ablation procedure in each patient. DFMCG and organization index (OIMCG) were calculated using fast Fourier transformation. Intracardiac electrograms (ICEs) in both the atria and the coronary sinus (CS) were mapped at 17 sites. Regional DFsICE were also determined.ResultsMean LA DFICE was higher than mean RA DFICE (6.40±0.66 versus 6.16±0.80 Hz, P=0.03). DFMCG in the channel having the highest OIMCG was 6.61±0.88 Hz in the frontal plane, 6.52±0.64 Hz in the lateral plane, and 6.42±0.62 Hz in the back plane (P=0.3). In each plane, DFMCG correlated with DFICE at the RA appendage (R=0.95, P<0.0001), the LA appendage (R=0.91, P<0.0001), and the CS (R=0.93, P<0.0001). DFECG in V5 modestly correlated with DFICE at the LA appendage (R=0.82, P<0.0001).ConclusionsMCG could more precisely detect the DFs in the LA and the CS than ECG. However, the usefulness of pre-procedural detection of the AF frequency gradient for ablation therapy needs to be evaluated in future prospective studies.

Electrophysiological mechanisms of long and short QT syndromes

“…It was proposed that the term QRS d /QRS could be a surrogate marker of CV dispersion coefficient based on the standard deviation of the mean CV [68]. Other non-invasive methods of assessing the function of the heart include magnetocardiography, which may provide additional insights into risk stratification in the future [69], [70], [71], [72], [73], [74], [75], [76].…”

Predictive value of unshielded magnetocardiographic mapping to differentiate atrial fibrillation patients from healthy subjects

“…Indeed, although experience is still limited to only few institution, contactless MCG is one of the most promising technology for non‐invasive cardiac electro‐anatomical imaging and accurate localization of arrhythmogenic substrates (Brisinda, Venuti, Sorbo, & Fenici, ; Fenici & Brisinda, ; Fenici, Brisinda, Venuti, & Sorbo, ; Kwong, Leithäuser, Park, & Yu, ). Several studies, all carried out in magnetically shielded rooms, have demonstrated the usefulness of MCG to study AF (Jurkko et al, , ; Kim & Ahn, ; Kim, Kim, Lee, & Ahn, ; Koskinen et al, ; Lehto et al, ; Lim et al, ; Mäntynen et al, ; Nakai et al, ; Sato et al, ; Yamada & Yamaguchi, ; Yamada, Tsukada, Miyashita, Kuga, & Yamaguchi, ; Yoshida et al, ). The reproducibility of automatically measured terminal high‐frequency component of signal averaged atrial magnetic signals was evaluated in PAF patients compared with controls (Koskinen et al, ).…”

Simulation of Extended Source Localization using sLORETA Method for Magnetocardiography

“…Since the real cardiac sources are considered to be extended sources, simulations with multiple dipoles are also performed. A normal MCG wave is obtained using the Iwate create project 64-channel MCG system 11) . An isomagnetic field map of the MCG wave at the R peak is shown in Fig.…”

“…Namely, the extension of the source depends on the source depth. MCG can detect heart signals not only at the front but also at the back of the torso, even though the signals detected at the back of the torso are very weak 11) . The assessments of the spatial filter based on the different examination method have not been studied.…”