Qualitative coronary flow evaluation of a pre-clinical percutaneous temporary aortic valve

Abstract

A published balloon-based percutaneous temporary aortic valve (TAV), with a specific fixed gap-to-aorta cross-sectional area ratio, was shown to provide haemodynamic support in acute aortic regurgitation (AR). The fixed gap of the balloon-TAV, however, limits the ability to optimize the gap size balancing coronary flow vs AR protection. Hence, a reduced diastolic gap may improve AR protection, but could reduce coronary flow and increase systolic TAV flow resistance. A new membrane-based TAV, which avoids these design limitations, could guide gap size optimization and advance the development into a pre-clinical tool. The re-designed TAV prototype has a membrane-cone collapsible in systole to reduce flow resistance and expands in diastole with a gap-to-aorta cross-sectional area ratio that can be tailored to optimize AR protection and coronary flow. Without the concern for systolic TAV flow resistance, a lower limit of the gap:aorta cross-sectional area ratio could be determined. The ability of the membrane-TAV design in determining an optimal gap:aorta ratio is tested in an in vitro flow chamber. Three prototypes with reducing gap:aorta cross-sectional area ratios (35%, 15%, 0%) were tested in a flow chamber of simulated acute severe AR. Correspondingly, increasing in forward cardiac output volumes, coronary flow:aortic regurgitant volume ratios and reduction in aortic regurgitant volumes were observed (p < 0.001) in the three models. The membrane-TAV concept contains a design feature for optimization of LV protection from acute AR and coronary perfusion by defining an optimal gap:aorta ratio. Along with the results from the balloon-TAV, a clinically useful percutaneous device for the management of acute severe aortic regurgitation is becoming possible.