Feasibility of Subcutaneous ECG Leads for Synchronized Timing of a Counterpulsation Device
A counterpulsation device (Symphony) that works synchronously with the native heart to provide partial circulatory support was developed to treat patients with advanced heart failure. Symphony is implanted in a ‘pacemaker pocket’ without entry into the chest, and requires timing with ECG for device filling and ejection. Surface leads are limited to short-term use due to signal distortion and lead management issues. Transvenous leads are a clinical standard for pacemakers and internal defibrillators, but increase the complexity of the implant procedure. In this study, the feasibility of using subcutaneous leads for synchronized timing of Symphony was investigated. ECG waveforms were simultaneously measured and recorded using epicardial (control) and subcutaneous (test) leads in a bovine model for 7-days (n = 6) and 14-days (n = 2) during daily activity and treadmill exercise. Landmark features and R-wave triggering detection rates for each lead configuration were calculated and compared. Lead placement, migration, durability, and infection were quantified using fluoroscopy and histopathological examination. There were 2,849 data epochs (30-s each) recorded at rest (133,627 analyzed beats) and 35 data epochs (20 min each) recorded during treadmill exercise (37,154 analyzed beats). The subcutaneous leads provided an accurate and reliable triggering signal during routine daily activity and treadmill exercise (99.1 ± 0.4% positive predictive value, 96.8 ± 1.5% sensitivity). The subcutaneous leads were also easily placed with minimal lead migration (0.5 ± 0.1 cm), damage (no fractures or failures), or infection. These findings demonstrate the feasibility of using subcutaneous leads for synchronized timing of mechanical circulatory support while offering the advantage of less invasive surgery and associated risk factors.
KeywordsSubcutaneous Electrocardiogram ECG leads Heart failure Mechanical circulatory support
This study was funded by NIH SBIR phase I grant 1R43HL102981-01. Funding was provided to SCR (Louisville, KY) and the University of Louisville by NIH-SBIR phase II (R43HL102981) and Kentucky Science & Technology (KSTC-184-512-08-054) grants.
Landon Tompkins, Robert Dowling, MD and Paul Spence, MD are employees of SCR Inc (Louisville, KY) with commercial interests in the development of the Symphony system. Eric Gratz is an employee of Abiomed Inc (Danvers, MA) with commercial interests in the development of the Symphony system.
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