Factors affecting electrogram sensing in an insertable cardiac monitor: Insights from surface electrocardiogram...

Area of Science:

• Cardiology
• Biomedical Engineering
• Medical Device Technology

Background:

• Accurate electrogram sensing by insertable cardiac monitors (ICMs) is crucial for reducing false alerts.
• Understanding factors influencing electrogram signal quality is essential for optimizing ICM performance.

Purpose of the Study:

• To evaluate how vector length, implant angle, and patient characteristics affect electrogram sensing in ICMs.
• To correlate surface electrocardiogram (ECG) mapping data with ICM electrogram readings.

Main Methods:

• Acquired 1800 precordial surface ECGs from 150 participants at varying interelectrode distances (75 mm, 45 mm) and vector angles (vertical, oblique, horizontal).
• Recorded ICM electrograms from a subset of 50 patients.
• Analyzed P-wave and R-wave amplitudes and visibility using specialized software, with a P-wave visibility threshold of > 0.015 mV.

Main Results:

• Longer vector lengths (75 mm vs. 45 mm) significantly increased P-wave (45%) and R-wave (53%) amplitudes.
• Oblique vector orientation resulted in superior P-wave and R-wave amplitudes.
• A vector length of 75 mm improved P-wave visibility (86% vs. 75%) compared to 45 mm.
• Moderate correlations were found between surface ECG and ICM electrogram amplitudes (ICC 0.74 for P-wave, 0.80 for R-wave).

Conclusions:

• Longer vector lengths and oblique implant angles are key factors for achieving optimal electrogram sensing with ICMs.
• These findings provide critical guidance for improving ICM implantation techniques and enhancing diagnostic accuracy.