A method for noninvasive beat-by-beat visualization of His bundle signals

Area of Science:

• Cardiology
• Biomedical Engineering
• Signal Processing

Background:

• Invasive His bundle signal (HBS) recording via electrophysiological study (EPS) is crucial for determining the HV interval.
• Noninvasive methods like body surface potential mapping (BSPM) and magnetocardiography (MCG) average many cardiac cycles to estimate HBS.
• Extracting beat-by-beat HBS noninvasively is difficult due to atrial signal interference and noise.

Purpose of the Study:

• To develop and validate a novel noninvasive technique for extracting His bundle signals (HBS) from single cardiac cycles.
• To overcome limitations of existing noninvasive methods in capturing beat-by-beat HBS.
• To assess the efficacy of the new method using magnetocardiography (MCG) data.

Main Methods:

• Developed a method combining interval-dependent wavelet thresholding (IDWT) and signal space projection (SSP) to remove artifacts from single heartbeats.
• Utilized a signal-averaged trace with prominent HBS as a guide for artifact elimination.
• Applied the method to MCG data from 21 subjects with known HV intervals (from EPS) and to BSPM data from five subjects.

Main Results:

• Successfully extracted HBS from single beats in 19 out of 21 subjects, with timing differences from EPS within -8 to 11 ms.
• Observed aligned HBS patterns in inter-beat contours, which were more apparent in stress-MCG than in BSPM.
• Determined the method's performance to be adequate for MCG data with a signal-to-noise ratio of at least 20 dB.

Conclusions:

• The developed method enables noninvasive, beat-by-beat extraction of His bundle signals (HBS).
• This technique shows promise for more accurate and accessible cardiac electrophysiological assessments.
• Further application in clinical settings for noninvasive HBS evaluation is suggested.