Evaluation of the in-vivo Chemical Reactivity of a Novel Co-polymer Insulation on Cardiac Leads in a Single-Center Study

Background Human in-vivo data on the chemical stability of different transvenous lead materials and in particular Optim leads are lacking. Objectives We sought to study the chemical reactivity of insulation materials by analyzing the Molar mass of extracted pacing and defibrillator leads Methods We collected extracted leads at Emory University Hospitals and sent leads with thermoplastic outer insulation material for molar mass analysis, a material characteristic that informs biostability. Leads were separated based on the chemical identity of the outer insulation material, and the molar mass was measured by an independent party. The extent of chemical reaction was compared across leads having different materials: poly(ether)urethane 55D, poly(ether)urethane 80A, and Optim. Results A total of 70 leads were extracted. The subset of extracted leads having outer insulation materials comprised of PEU or Optim were analyzed for molar mass, where implant times ranged from 0.12 years to 16.26 years. The rate of chemical degradation was compared by plotting the extent of reaction (Mn(t=0)/Mn(t)) as a function of implant time. The Optim molar mass decreased to 40 % of its initial value at 10 years of implant. No change in the molar mass of the PEU insulations could be resolved over the same 10-year implant time. Conclusion Because the molar mass of a polymer is directly related to its mechanical integrity, the observed decrease in molar mass of Optim likely translates into premature insulation defects and is consistent with the observed increased rate of electrical malfunction/noise in this subset of cardiac leads.