Date of Award

12-2016

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Mechanical Engineering

Committee Member

Dr. Richard Figliola, Committee Chair

Committee Member

Dr. Donald Beasley, Committee Member

Committee Member

Dr. Tiffany Camp, Committee Member

Committee Member

Dr. Ethan Kung, Committee Member

Abstract

Hypoplastic Left Heart Syndrome (HLHS) is a congenital heart disease where the left ventricle and ascending aorta are underdeveloped. The first of three palliative surgeries for this malformation is the Norwood procedure. In this surgery, an opening is made between the left and right atrium so that all blood can flow into the right ventricle (RV). A reconstructed aorta is anastomosed (connected) to the RV so that the RV can pump oxygenated blood to the body (the systemic circulation). To divert part of the systemic blood flow to the pulmonary circulation, the modified Blalock-Taussig Shunt (mBTS) is connected from the innominate artery to the pulmonary artery. However, Norwood patients with an mBTS may experience retrograde flow from the coronary circulation (which supplies blood to the heart) to the pulmonary circulation via the mBTS. This shunt steal of coronary blood can lead to detrimental issues such as myocardial ischemia leading to right ventricular dysfunction. In this study, a multi-scale model of the Norwood procedure couples a three-dimensional (3D) test section of the reconstructed aortic arch with a lumped parameter network (LPN) describing the Norwood patient's global hemodynamics. Previously, only in silico multi-scale models of the Norwood circulation have modeled the coronary circulation and the effects of varying mBTS sizes on coronary perfusion. Here, a novel in vitro coronary circulation model is adapted from such in silico studies and implemented into a previously validated in vitro mock circulatory system (MCS) of the Norwood with mBTS palliation. The MCS was verified against an analytical model and validated using a patient-specific test section and data. A parametric test in which the size of the mBTS inner diameter was varied from 3mm to 4mm was performed. The results showed that increasing mBTS size results in decreased diastolic aortic pressure, which decreases coronary blood flow (CBF) during diastole.

Share

COinS