Demand for heart transplants far exceeds supply. This is often attributed to the high percentage of donor hearts that are discarded due to cell injury and to the narrow six-hour time window currently available for transplantation. A method called ex vivo heart perfusion (EVHP) enables the use of damaged donor hearts and extends the available time window by preserving the heart's beating function outside the body from the time of donation until transplantation. Present work is concerned with the fluid mechanics of the flow loop and corresponding impact on cardiac performance. In particular, this work has undertaken the development of a mechanical flow loop analogous to the left flow loop of the EVHP system in order to isolate the study of phenomena that characterize this analogous in vivo region, such as the presence of the highly compliant aorta. The focus of this investigation is to determine the effect of the mock aortic tubing compliance on the downstream pressure and flow fields, with the ultimate goal of understanding their effect on pump performance. To this end, a silicone mock aortic section has been developed to simulate a range of in vivo compliant conditions. A physiological pulsatile waveform was generated using a commercial left ventricular assist device (VAD) and the flow fields downstream of the compliant section were acquired using time-resolved particle imaging velocimetry (PIV). Findings include pressure waveforms at the mock aorta inlet and novel visualizations of the downstream flow fields.