Aortic valve hydrodynamics: considerations on the absence of sinuses of Valsalva.

BACKGROUND AND AIM OF THE STUDY: The study aim was to compare the hydrodynamics of the Carpentier-Edwards Magna 21 (CEM) and St. Jude Medical Biocor-Epic-Supra 21 (SJME) valves at increasing stroke volume and pulse rate in two different aortic conduits, namely straight and with sinuses of Valsalva present. METHODS: Both valve types were tested in the aortic chamber of the Sheffield pulse duplicator, at rates of 70, 80 and 90 beats/min, and stroke volumes of 50 and 60 ml. The systolic and diastolic performances were each recorded. The leaflet coaptation time, ventricle isovolumetric time and maximum instantaneous flow rate were also recorded. RESULTS: Regardless of the aortic conduit, CEM valves showed a significantly lower gradient than SJME valves (p < 0.05), and a significantly larger effective orifice area (EOA) (p < 0.05); the latter parameter was unaffected for both valves, at an increasing pulse rate (p > 0.05). The maximum transvalvular flow velocity was significantly higher in the straight conduit for both valves (p < 0.05). With regards to diastole, the SJME valve showed the lowest regurgitant volume (p < 0.05). The leaflet coaptation time was significantly shorter for the SJME valve than for the CEM valve (p < 0.05), but when tested in a straight conduit it was shortened significantly for both valves (p < 0.05). CONCLUSION: An absence of the sinuses of Valsalva may modify the diastolic and systolic behaviors of the tissue valve leaflets by reducing the time required for leaflet coaptation, and increasing the valve closing volume and maximum transvalvular flow velocity. It is speculated that these hydrodynamic changes may increase the working stress on the valve tissue, leading to possible premature structural valve deterioration.

The changing hydrodynamic performance of the decellularized intact porcine aortic root: considerations on in-vitro testing.

BACKGROUND AND AIM OF THE STUDY: The most effective method for decellularization of the intact porcine aortic root remains controversial. Additionally, the hydrodynamic effect that such treatment may have on aortic roots has never been previously investigated. The study aim was to compare the in-vitro hydrodynamic performances of intact porcine aortic roots, both before and after decellularization treatment. METHODS: Fifteen fresh porcine aortic roots were tested in the aortic chamber of the Sheffield pulse duplicator (SPD). For study purposes, the roots were first sutured to a silicone aortic root and then hydrodynamically tested. After in-vitro testing, the fresh porcine aortic roots, while still fixed within the silicone root, were decellularized according to various protocols (TRI-COL, TRI-DOC, sodium dodecyl sulfate (SDS) 0.03%, and SDS 0.1%). After decellularization, the valve roots were re-tested, adopting identical testing conditions. Forward flow pressure drop, closing leakage volumes, effective orifice area (EOA), and stroke work loss were each monitored. Three roots, used as a control group, were tested in identical fashion before and after storage (without decellularization) for comparative purposes. RESULTS: The TRI-COL- and TRI-DOC-treated porcine aortic roots showed significantly lower transvalvular gradients, lower stroke work loss, lower valve resistance, and higher EOA than fresh intact porcine roots. In contrast, SDS 0.1%-treated porcine aortic roots showed opposing results, with the transvalvular gradients, stroke work loss and valve resistance each higher, and the EOA lower, than pre-treatment values. SDS 0.03% treatment had no significant effect on the hydrodynamic performance. After decellularization in all treatment groups, the diastolic parameters, total regurgitant volume and valve closing volume were each non-significantly increased. The aortic roots used as a control group showed similar results before and after storage. CONCLUSION: Based on these results using the SPD, all treatments except for SDS 0.03% modified the systolic and diastolic functions of intact porcine aortic roots.