Leadless pacemaker implementation at the right atrial appendage apex: An initial preclinical assessment.

Area of Science:

• Cardiovascular medicine
• Biomedical engineering
• Medical device development

Background:

• Current leadless pacemakers, like the Medtronic Micra, are primarily designed for right ventricular implantation, limiting options for atrial pacing.
• Atrial pacing is crucial for certain cardiac conditions and can be beneficial in dual-chamber pacing systems.

Purpose of the Study:

• To evaluate the feasibility and efficacy of implanting a leadless pacemaker in the right atrial appendage (RAA) apex.
• To assess the short-term (1-week) and long-term (3-month) pacing performance of a leadless device in a preclinical model.
• To identify potential safety concerns for long-term implantation in the RAA.

Main Methods:

• A leadless pacemaker (Micra Transcatheter Pacing System - TPS) was implanted in the RAA apex of four minipigs (45.8 ± 10.0 kg).
• Pacing parameters including R-wave amplitude, pacing threshold, sensitivity, and impedance were monitored.
• Device performance and myocardial interaction were assessed at 1 week and 3 months post-implantation.

Main Results:

• Successful implantation of the Micra TPS in the RAA apex was achieved in all subjects.
• Initial pacing parameters were satisfactory, and sensitivity, threshold, and impedance remained stable over the 3-month period.
• Histological examination at 3 months revealed deep myocardial penetration by the device.

Conclusions:

• Right atrial appendage apex placement of the Micra TPS is a feasible strategy for leadless atrial pacing.
• The observed deep myocardial penetration necessitates device modification to ensure safety and efficacy for long-term use.
• Further research and device redesign are required before clinical application in dual-chamber pacing systems.