[Where should the implantable ECG event recorder be placed?].

Area of Science:

• Cardiology
• Biomedical Engineering
• Medical Device Technology

Background:

• Electrocardiogram event recorders (ECG-ER) are crucial for long-term cardiac monitoring.
• Optimal lead placement is essential for high-quality ECG signal acquisition.
• Previous studies have not definitively established the best anterior thoracic site for ECG-ER implantation.

Purpose of the Study:

• To compare bipolar electrocardiogram (ECG) quality at various anterior thoracic sites for ECG-ER implantation.
• To determine the preferable implantation site and orientation for ECG-ERs.
• To evaluate the impact of electrode positioning on ECG signal integrity.

Main Methods:

• Bipolar ECGs were recorded in 70 patients at multiple anterior thoracic sites (subclavicular, parasternal, axilla, apex, subxiphoid) with a 4 cm lead distance.
• ECG quality was assessed based on QRS amplitude, P-wave visibility, pacemaker spike detection, QT interval measurement, and bundle-branch block identification.
• Comparisons included standard Lead II, vertical vs. horizontal electrode positions, and electrode orientation (skin vs. muscle).

Main Results:

• The left parasternal site yielded the best ECG quality and agreement with standard Lead II in 67% of patients.
• Significantly lower quality was observed at right parasternal, left subclavicular, apical, and subxiphoid sites (p < 0.001).
• Vertical electrode positioning resulted in higher QRS amplitude and more visible P-waves compared to horizontal positioning. Electrodes placed towards the muscle caused significant noise.

Conclusions:

• The left parasternal region is the recommended implantation site for ECG-ERs.
• Vertical electrode placement with electrodes oriented towards the skin is advised for optimal signal acquisition.
• These findings can improve the diagnostic yield of ECG event monitoring.