The porous-surfaced electrode: a new concept in pacemaker lead design

Area of Science:

• Biomedical Engineering
• Cardiology
• Materials Science

Background:

• Endocardial pacemaker electrodes face challenges like unstable positioning, increased stimulation thresholds, and diminished signal amplitude, especially in the atrium.
• Porous metal surfaces have previously demonstrated the ability to support stable tissue ingrowth.

Purpose of the Study:

• To evaluate the performance of porous-surfaced endocardial pacing electrodes in the atrial position.
• To compare the long-term stability and electrical performance of porous versus smooth-surfaced atrial electrodes.

Main Methods:

• Two groups of six dogs each received J-shaped atrial leads with Elgiloy electrode tips.
• Leads featured either smooth (control) or porous (20-50 micron particle size) surfaces.
• Stimulation thresholds and P-wave amplitude were measured over 30 weeks; electrode fixation and tissue reaction were examined via microscopy.

Main Results:

• Porous-surfaced electrodes showed significantly lower long-term stimulation thresholds (less than one-third of controls at 30 weeks).
• A small but significant improvement in sensed P-wave amplitude was observed in the porous group.
• All porous electrodes exhibited fixation via fibrous tissue ingrowth, unlike smooth electrodes which showed no fixation and were separated from the myocardium by granulation tissue.

Conclusions:

• Porous-surfaced endocardial electrodes provide superior long-term performance in the atrial position.
• Tissue ingrowth into porous electrode surfaces promotes stable fixation, maintaining proximity to myocytes and enhancing electrical function.
• This fixation mechanism addresses key challenges associated with traditional endocardial pacemaker leads.