Clinical application of magnetocardiography

Abstract

Magnetocardiography is a noninvasive contactless method to measure the magnetic field generated by the same ionic currents that create the electrocardiogram. The time course of magnetocardiographic and electrocardiographic signals are similar. However, compared with surface potential recordings, multichannel magnetocardiographic mapping (MMCG) is a faster and contactless method for 3D imaging and localization of cardiac electrophysiologic phenomena with higher spatial and temporal resolution. For more than a decade, MMCG has been mostly confined to magnetically shielded rooms and considered to be at most an interesting matter for research activity. Nevertheless, an increasing number of papers have documented that magnetocardiography can also be useful to improve diagnostic accuracy. Most recently, the development of standardized instrumentations for unshielded MMCG, and its ease of use and reliability even in emergency rooms has triggered a new interest from clinicians for magnetocardiography, leading to several new installations of unshielded systems worldwide. In this review, clinical applications of magnetocardiography are summarized, focusing on major milestones, recent results of multicenter clinical trials and indicators of future developments.

Contactless magnetocardiographic mapping in anesthetized Wistar rats: evidence of age-related changes of cardiac electrical activity

“…Multichannel MCG mapping measures the magnetic fields (MF) generated by cardiac activation currents, with minimal distortion due to the shape and conductivity of the lungs and torso (20, 28). The advantages of contactless MCG mapping are as follows: 1) the ability to study conscious animals without movement artifacts (65), 2) the potential to provide diagnostic information not revealed by ECG (1,29,36,37,41,43,44,51,54,62,64,69,71,74,75), 3) the fixed-sensors geometry (42), which minimizes errors in localization of intracardiac sources (30) and three-dimensional electroanatomic imaging of arrhythmogenic phenomena (77), and 4) the localization of VR heterogeneities associated with areas of myocardial injury (50).A major problem with MCG mapping of small hearts might be an unfavorable signal-to-noise ratio (S/N), because the cardiac sources are very weak. For this reason, most experimental MCG studies of small animal hearts have been performed in magnetically shielded rooms (4,22,23,65,72).…”

A simplified HTc rf SQUID to analyze the human cardiac magnetic field

“…From MCG signals, a great deal of useful information concerning cardiac disease can be obtained: QT and QRS prolongation caused by myocardial abnormalities were studied using the late fields of MCG signals; [1][2][3]25 T wave deviation of MCG signal is used to detecting IHD. [1][2][3]26 These characteristics indicated MCG recording can provide value information for clinicians. The written informed consent was acquired from the volunteer.…”

“…Successful results have been reported in clinically relevant applications. [1][2][3][25][26][27][28] Our practical studies can provide 3D imaging, isomagnetic field maps and CMDs at T wave with sufficient spatial resolution. These results are considered as a major argument for IHD.…”

“…Recently, it has been shown that MCG provides practical and informative for diagnosing of the pre-excitation syndromes, ischemic heart disease (IHD) and the accurate localization of arrhythmogenic substrates and accessory pathways for catheter ablation or surgery with sufficient spatial accuracy necessary for clinical purpose, [1][2][3] this useful technique based on superconducting quantum interference device (SQUID) magnetometer, no matter on cryogenic or hyperthermia, have been developed. [4][5][6] Conceptually, MCG is not new.…”

Complex narrow band-pass filters for QRS detection in contactless magnetocardiograms of small animals

“…MCG is the measurement of the magnetic field generated by the same currents that give rise to the ECG. Hence the MCG contains to a large degree information similar to the ECG [2].…”