NITRIC OXIDE RELEASING PACING LEAD TO PREVENT INFECTION IN CARDIAC PACING

Background: Effective prevention of pacing lead infection could reduce morbidity and save lives. It has been demonstrated that nitric oxide (NO) can inhibit bacterial adhesion and reduce biofilm formation. We tested a diazeniumdiolated dibutylhexanediamine (DBHD/N2O2, a potent NO donor) coated pacing lead to prevent its bacterial infection.

Methods: Silicone pacing lead was coated with two layers of 25 weight% DBHD/N2O2 in Carbosil and topped with one layer of plain Carbosil. The NO release profile of the coated lead is measured with an ozone chemiluminescent method at 37°C in phosphate buffered saline (PBS, pH=7.4). In a bioreactor the lead is then exposed to bacterial cultures of S. aureus and P. aeruginosa and its antibacterial capacity evaluated by biofilm homogenization and plating on agar for CFU counting of viable bacteria per surface area. Complete pacing system with the DBHD/N2O2 coated pacing lead is then implanted in small animal model (rabbit) and tested for function and durability.

Results: Initial NO flux of DBHD/N2O2 coating was 0.8±0.1 [x10^10 mol/min/cm2] and stayed between the effective range >0.5 flux unit for seven days. Preliminary results on coated catheter surfaces demonstrated almost 95% decrease of biofilm formation: 89±9.7 vs. 5.2±1.1 x10^3 CFU (P<0.001). In-vivo, cardiac pacing was properly functional in all subjects for over 6 months with mean impedance of 750 Ohm, average bipolar ventricular sensing of 9.2mV (min 7.4, max 12) and pacing threshold of 1.7V@0.4ms (min 0.2, max 2.7).

Conclusion: Presented pacing lead with DBHD/N2O2 coating demonstrated a potent antibacterial effect while retaining optimal pacing parameters. This effective elimination of biofilm formation can likely prevent potential clinical infection especially in complex pacing procedures or immunocompromised patients.