SUMMARY

Coronary artery disease is the most common type of cardiovascular disease, affecting > 18 million adults, and is responsible for > 365k deaths per year in the U.S. alone. Wall shear stress (WSS) is an indicator of likelihood of plaque rupture in coronary artery disease, however, non-invasive estimation of 3D blood flow velocity and WSS in coronary arteries is challenging due to the requirement for high spatial resolution at high penetration depths. For this reason, a catheter-based forward-viewing intravascular ultrasound (FV IVUS) imaging system is being developed to estimate real-time 3D velocity fields in patients already undergoing minimally-invasive diagnostic procedures in the cardiac catheterization lab. A novel WSS estimation technique was developed for a forward-viewing high frequency ultrasound array transducer in a coronary artery. Specific outcomes were: 1) Two different ultrasound-based blood flow velocity estimation approaches (Doppler and echo PIV) and resulting WSS estimates were compared in a patient-specific coronary artery geometry. 2) Motion-compensated blood flow velocity and WSS estimation techniques were developed to accurately estimate blood flow velocity and WSS in the presence of dynamic cardiac motion. 3) Developed blood flow velocity and WSS estimation techniques were demonstrated in the coronary artery of an ex vivo beating pig heart. Approaches for characterizing the coronary hemodynamic environment in 2D and 3D using forward-viewing, high frequency ultrasound transducer were developed and demonstrated for use in a catheter-based device. Future work will include in vivo validation of velocity and WSS estimation techniques using catheter-based FV IVUS imaging system.