Research into flow on a model of the aorta and on mechanical systems for the assistance of the heart

Based on a previous investigation, the author designed and constructed a hydraulic model of the aortic tree which renders possible an experimental analysis of two basic mechanical systems for the support of failing cardiovascular circulation: an intra-aortal balloon contrapulsation and by-pass blood pump. Another experimental equipment was built for the research and testing of mechanical and biological heart valves and the artificial heart. The realized measurements show that the introduction of intra-aortic balloon contrapulsation seems effective in the case of a sufficiently elastic aorta. For a detailed flow pattern inside the by-pass pump and blood chamber of the artificial heart we used a visualization method and laser-Doppler anemometry (LDA). The LDA measuring system was also used for evaluation of turbulent shear stresses downstream of mechanical heart valves. From the flow visualization we observe flow reversal and separation regions through the cardiac cycle. The LDA velocity profile measurements also show relatively large velocity gradients which may induce higher turbulence stress, especially at peak systole and therefore large shearing action on the formed elements of blood.