In-vitro Benchmarking of Currently Available Heart Valve Prostheses for Surgical and Percutaneous Treatment of Aortic Stenosis With Small Annulus, Followed by In-vivo Validation

The goal of the study is testing hydrodynamic performances of various surgical and transcatheter valve prostheses, also according to the technique of implantation. A dedicated Magnetic Resonance Imaging (MRI) compatible mock circulation simulator will be implemented, including a circuit filled with blood-alike fluid, a pulsatile pump, and 3D printed silicon phantoms of ascending aorta.

Data collection will focus on structural changes of prostheses in response to flow, including leaflet motion, gradients and flows across the valve, taken either by direct pressure measurements and 4D Flow MRI. As second step, trans-valvular gradients and valve performance in patients implanted with the same tested valves will be measured by echocardiogram and 4D Flow MRI.

Degenerative aortic valve stenosis is a common disease in people >65 years, with an estimated rate approaching 10% in Western countries. Despite progress in diagnosis and therapy, invasive treatments still represent the only definitive option, including surgical aortic valve replacement (SAVR) and more recently less-invasive transcatheter aortic valve replacement (TAVR).

Patients with small aortic annulus constitute a challenging subset, where the need to minimize both procedural and longterm risk entwine with that of avoiding patient-prosthesis mismatch (PPM) and structural valve deterioration (SVD). The common denominator appears to be blood flow, which has demonstrated to play a pivotal role in late complications. In fact, PPM is associated with earlier structural valve dysfunction and higher long-term mortality. To obtain larger effective orifice area, surgeons must consider many different procedures (annular enlargement), valve models (stented valves, subcoronary stentless valves, or rapid deployment valves) or different techniques of valve suturing. However, in the literature, there is no clear indication to the ideal strategy of treatment so far. Heart valve prostheses generate turbulent flow in the aortic root and the ascending aorta. Hydrodynamic instabilities and turbulent flow may produce clinically adverse events. Therefore, a thorough evaluation of hemodynamic and flow conditions should be tested, to provide the most effective treatment strategy for each patient.

Both units regularly perform surgical as well as percutaneous aortic valve replacements: patients from both centres will be enrolled to evaluate post-implant valve performances by echocardiogram and MR imaging.