This work extends our understanding of the interaction between circulatory assist devices and either the human circulatory system or mock circulatory systems. The major results depend on both linear and nonlinear dynamic effects, and have significant impact on both the design of mock circulatory systems and our analysis of the human circulatory system.

Two complementary approaches were used, one theoretical and the other experimental. A comprehensive review of mock circulatory systems was performed. Multiple mathematical models were developed in order to reach the fundamental objective of gaining a better understanding of human circulatory system dynamics. These models are based on newly-developed analogies that equate the proximal arterial system to a nonlinear massspring-damper system, sometimes called an "impact oscillator" or "Fermi oscillator." This equivalence has implications for both VAD efficiency and stability, and also makes predictions about natural heart behaviour.

The experimental effort, using a specially designed mock circulatory system in varying configurations, was used to improve the confidence in the numerical predictions. Most existing mock circulatory systems were found to be a poor representation of the human arterial tree and an inadequate dynamic testbed for artificial heart development, although they are still useful for long-term reliability testing. Results from both mathematical simulation and experimental testing show that the addition of a second arterial compliance element to an existing mock circulatory system improves the dynamic representation, and the resultant arterial pressure waveforms more closely match those seen in the human body. Nonlinear aspects of the behaviour offer possible explanations for several cardiac conditions, and provide promising direction for future research.