A novel approach to the in vitro hydrodynamic study of the aortic valve : mock loop development and test

The aortic root functional unit (ARFU) is a complex structure whose functions are strictly dependent on the biomechanical interaction among each of its anatomically defined elements. The classical approach to the in vitro study of aortic hydrodynamics does not take this complexity into account. We propose a novel methodology based on the possibility to house whole natural ARFU samples in a purposely designed pulsatile mock loop, allowing for aortic surgery simulation. To point out the usability and potentialities of the device, the mock loop was tested with untreated porcine ARFU samples and with one ARFU prosthesized with a state-of-the-art bioprosthesis. The sample holder design was proved to allow the clinician to house and treat the ARFU sample in the mock loop with easiness and repeatability. The valve leakage with the prosthesized ARFU was comparable with literature data, and Effective orifice areas were consistent with the constructor's data. In contrast, the recorded pressure drops exceeded the data from the manufacturer and were quite aligned with in vivo postop echo-Doppler data acquired in implant recipients. This result suggests that our apparatus and methodology provide a way to investigate aortic hydrodynamic phenomena that resemble in a close way to those taking place in the final recipients' circulation.