High-resolution magnetic measurements of human cardiac electrophysiological events

Noninvasive Determination of HV Interval Using Magnetocardiography

“…Indeed, this has been critical for a more precise measurement of the HV interval. Moreover, the present work bridges independent assessments on His‐Purkinje system (HPS) depolarization on an electrophysiological overtone (investigating the origin of ramps and their relation to HPS) and those on a clinical perspective 6,10,11 (reporting noninvasive measurement of the HV interval to be used for clinical studies). The fact that the HV intervals determined by applying the MFM‐based criteria could be validated with those inferred from the invasive EP study strengthens this aspect.…”

“…Noninvasive measurement of His‐bundle signals using BSPM and MCG has been reported by several groups so far. However, as shown in Figure , highly resolved features corresponding to the His‐bundle signal‐based on SAMCG/SAECG data, comparable in timing to those measured directly using EP, have been reported in the present work.…”

“…Encouraged by the sensitivity and the complimentary information offered by these sensors in the measurement of very weak cardiac magnetic fields inside magnetically shielded rooms, SQUID‐based magnetocardiography (MCG) was thought to be a more appropriate technique in tracking the His‐bundle signals than the body surface potential measurements or the high‐resolution ECG . Subsequently, signal‐averaged MCG (SAMCG) traces with significant augmentation in the signal‐to‐noise ratio (SNR) revealing some bumps in the PR segments attributed to the electrical activity of the His bundle were reported. Some improvements in the measurement, including the averaging methodology overcoming the limitations of the earlier studies in enhancing the reliability of noninvasively measuring the His‐bundle signals using MCG, have been reported, emphasizing that the choice of the fiducial point taken for averaging may, indeed, be very critical for a proper evaluation of the His‐bundle signal.…”

MAGNETOMETRY USING ELECTROMAGNETICALLY INDUCED TRANSPARENCY IN A ROOM TEMPERATURE VAPOUR CELL - Developing an Optical Magnetometer that Utilises the Steep Dispersion Curve Observed in EIT to Detect Ti

“…The largest magneto-physiological signal in the body is created by the heart's QRS peak which corresponds to the contraction and relaxation of the cardiac muscle during a single heart beat. The magnetic fields associated with this process are of the order of tens of picotesla, although the more clinically important signals that are unobservable with ECG are formed by the cardiac conducting system, which are super-imposed on the field and are less than 1 pT (Fenici et al, 1983).…”

Enhancing the Reliability in the Noninvasive Measurement of the His Bundle Magnetic Field Using a Novel Signal Averaging Methodology

“…Noninvasive surface recordings of the HB electrical activity have been made using both signal averaged electrocardiography (SAECG) [1][2][3][4][5][6][7][8] and magnetocardiography (SAMCG). [9][10][11][12] A common methodology is the averaging over many cardiac cycles to reduce the random noise components and artifacts that are uncorrelated with reference to a chosen fiducial point in the cardiac cycle. In a SAECG study on dogs, 1 a region designated "G Complex" was observed in the PR segment, whose onset was almost synchronous with the HB deflection seen in a corroborative EP.…”