Pacing, Sensing and Defibrillation Electrode Coatings

DESCRIPTION (provided by applicant): The development of low polarization electrode coatings for cardiac pacing, sensing and defibrillation is proposed. These coatings address the needs of the cardiac rhythm management (CRM) industry in the development of low-polarization pacing, low impedance defibrillation, and post-stimulus sensing methodologies. The coatings are based on films of sputtered iridium oxide (SIROFs) and IrTi-oxide with tailored surface morphologies that maximizes low-polarization charge-injection. The addition of titanium to form a mixed, IrTi-oxide significantly enhances the chemical and physical stability of the coatings without compromising pacing and sensing performance. The development of IrTi-oxide in Phase I is considered significant, since it provides a means through siloxane chemistry to covalently attach a broad range of functional organic species to the surface of the electrode to enhance biocompatibility and moderate inflammatory responses. The Phase II Aims are 1) To develop robust, low-cost coatings for cardiac electrodes that reduce pacing thresholds and permit reliable sensing of cardiac electrical activity; 2) To develop organically functionalized coatings for cardiac electrodes that reduce fibrotic tissue encapsulation and lower pacing thresholds relative to non-functionalized electrodes, and 3) To develop low-impedance coatings that reduce defibrillation thresholds (DFTs) of implantable cardioverter defibrillator (ICD) electrodes. Reduced thresholds and improved sensing will benefit the patient by enhancing the efficacy of the implant and by increasing the time between surgical procedures necessary to replace batteries. The SIROF and IrTi-oxide will be lower cost than competing coating materials (e.g. TiN), making them attractive commercially. In Phase II, in vitro assessments of the anti-inflammatory properties of covalently functionalized organic surface coatings will be made and these coatings evaluated for long-term stability by accelerated in vitro testing. The performance of SIROF, IrTi-oxide and functionalized IrTi-oxide for pacing and defibrillation will be assessed experimentally. As a step towards clinical implementation, the more optimum coatings will be evaluated for chronic pacing in a sheep model and for reduced DFTs in an acute pig model. The in vivo studies will be done with collaborators at the University of Alabama.