In Situ Lead Tester for Implantable Devices

DESCRIPTION provided by applicant Implantable cardioverter defibrillator ICD systems comprise a subcutaneous generator connected to the heart by a transvenous multilumen defibrillation lead The leadandapos s insulated cables carry physiological electrical signals from the heart to the generator and when necessary transmit therapeutic shocks from the generator to the heart to correct life threatening arrhythmias Leads comprise the weakest link in ICD systems as evidenced by recalls affecting hundreds of thousands of patients Lead failure diagnostics in present ICDs and those under development suffer from inherent and irremediable limitations especially for detecting insulations breaches the most common cause of lead failure Thus insulation breaches commonly present with serious complications Our objective is to develop a novel instrument that detects subclinical lead failures accurately and is suitable for evaluating in situ leads The principle behind this instrument is that subclinical physical changes in insulation alter the capacitance between lead conductors and external conductive blood and tissue resulting in changes in high frequency HF measurements of impedance In our phase study we confirmed that insulation breaches alter HF impedance using both novel electromagnetic EM modeling and in vitro testing In the present study we propose to expand both EM modeling and in vitro testing to construct an instrument that applies high frequency lead integrity HFLI testing to implanted leads and to test this instrument in animals Such an instrument would fulfill a significant unmet clinical need At ICD generator change accurate identification of leads that will fail within the anticipated year service lifeof new generators would permit prophylactic lead replacement reducing both patient morbidity and costs from lead failures and risks and costs of multiple operations Ultimately HFLI technology could be incorporated into the ICD generatorandapos s circuitry For new lead designs HFLI testing could play a critical role either to confirm expected performance or identify subclinical insulation problems permitting a problematic lead to be withdrawn at an earlier stage PUBLIC HEALTH RELEVANCE An implantable cardioverter defibrillator ICD is a small battery powered electrical impulse generator that is implanted in patients who are at risk of sudden cardiac death due to ventricular fibrillation and ventricular tachycardia The device is programmed to detect cardiac arrhythmia and correct it by delivering electric shocks or pulses Implantable cardioverter defibrillators have demonstrated clear life saving benefits