Efficacy of subcutaneous electrocardiogram leads for synchronous timing and aortic root cannulation for chronic counterpulsation therapy." (2016). Electronic Theses and Dissertations. Paper 2358. for allowing me the opportunity to join their research group in the fall of 2013. I would also like to thank Karen and Laura Lott for the countless hours of tutelage they have provided when I worked at CII as a co-op student. I am most grateful toward Dr. Gretel Monreal for always keeping me in high

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... rits and for Mr. Sobieski and Dr. Slaughter for giving me the opportunity to learn in the clinic and allowing me to find my career aspiration of practicing medicine. I am very appreciative of Dr. Guruprasad Giridharan for being an excellent mentor on this project and being exceedingly helpful through all of my road blocks. I could not have finished this project without him. I am also very appreciative toward Dr. Sean Warren for helping me with the MATLAB code used for ECG R-wave identification and comparison. vi ABSTRACT Background: Counterpulsation devices (CPD) require electrocardiogram (ECG) lead implantation for timing device filling and ejection with the native heart. Nonimplantable leads limit the scope of CPD treatment to short-term therapy. Standard transvenous/epicardial ECG leads increase the invasiveness of therapy. Methods: To overcome these limitations, subcutaneous ECG leads were tested in chronic (n=6) and acute (n=5) bovine models. ECG waveforms from clinicalgrade epicardial (control) leads and subcutaneous (test) leads were simultaneously recorded resulting in 830 data epochs (30-s each) for a total of 44,614 heart beats. Device triggering using R-wave detection was calculated for each lead type and compared. Additionally, the hemodynamic benefits of CPD with aortic cannulation (n=5) was investigated during normal and pharmacologically-induced heart failure, hypertension, and hypotension test conditions. Results: The subcutaneous leads provided 98.9% positive predictive value and 98.9% sensitivity compared to the epicardial ECG leads. Out of 40 subcutaneous leads implanted in chronic animals, lead migration (sensing-end movement >0.5cm, n=1) and lead fracture (n=1) were observed in two leads but did not adversely impact triggering efficacy due to lead redundancy. The CPD vii cannulated to the aorta showed diminished left ventricular (LV) external work, LV end diastolic volume, and LV end systolic volume during 1:1 support compared to baseline in pharmacologically induced heart failure (HF). The CPD also augmented cardiac output, aortic mean pressure, aortic pulse pressure, and mean coronary artery flow. Conclusion: These findings demonstrate the efficacy of chronic, subcutaneous ECG leads for CPD timing. The hemodynamic feasibility of the CPD cannulated to the aorta is equivalent or better than subclavian artery cannulation because of the proximity to the heart, which may increase the size of CPD patient population for warranted cases.