[Maturation of the electrode-endocardium interface]

Area of Science:

• Biomedical Engineering
• Cardiac Electrophysiology
• Materials Science

Context:

• Implanted pacemaker leads can cause endocardial inflammation and fibrosis, increasing stimulation thresholds.
• Chronic threshold values correlate with electrode surface area, influenced by mechanical factors like tension and tip design.
• The electrical factor, specifically current density at the endocardial-electrode interface, remains understudied in fibrosis genesis.

Purpose:

• To investigate the correlation between current density at the endocardial-electrode interface and cardiac fibrosis.
• To evaluate the impact of different voltage settings on pacing thresholds, R wave, and impedance.
• To minimize mechanical factors and isolate the effect of electrical stimulation on fibrosis.

Summary:

• An experimental study in 12 dogs assessed fibrosis development using leads with varying current densities (0, 2.5, 5 volts).
• Measurements included pacing thresholds, R wave, and impedance at implant and explant (8 and 35 days).
• Results showed statistically significant differences between reference and active electrodes, with higher current density leading to more fibrosis, higher thresholds, lower R waves, and lower impedances.

Impact:

• Findings suggest that leads stimulating with higher current density induce greater fibrosis and negatively impact pacing parameters.
• The study highlights the importance of managing current density to mitigate fibrosis and maintain optimal pacemaker function.
• Stimulating cardiac tissue at lower voltages is recommended to reduce adverse tissue reactions and improve long-term lead performance.