Impact of transcatheter aortic valve size on leaflet stresses: implications for durability and optimal grey zone sizing

Abstract

Aims: As indications for transcatheter aortic valve replacement (TAVR) continue to expand towards younger and lower-risk patients, durability becomes an increasingly important question. Durability decreases as leaflet stresses increase, but the impact of transcatheter heart valve (THV) size on stress is unknown. Patient annulus sizes can fall within "grey zones" between 2 TAVR sizes. Our aim was to examine the impact of balloon-expandable THV size on leaflet stresses.Methods and results: SAPIEN XT 23 mm, 26 mm, and 29 mm size valves underwent micro-computed tomography scanning to create THV computational models then loaded to systemic pressure using finite element software. THV leaflet maximum principal stresses were 1.69 MPa (23 mm), 1.70 MPa (26 mm), and 2.12 MPa (29 mm) at mean arterial pressure. For intermediate annulus sizes, undersizing the larger THVs yielded lower leaflet stresses than oversizing the smaller THVs.Conclusions: Increasing THV size yielded greater leaflet maximum principal stresses, which could suggest a relationship between THV size and long-term durability. For annulus "grey zones" sizes, undersizing the larger THV resulted in lower leaflet stresses than oversizing the smaller THV. These results may influence optimal device sizing, as THV durability remains an important, unanswered question.

Evaluation of the Transcatheter Aortic Valve Replacement Results in Patients with Borderline Aortic Annulus and the Impact of Under- or Oversizing the Valve

“…Hereby, based on the results of our study and very limited previous data about borderline annulus patients, it does not seem possible to make certain recommendations regarding valve selection and procedural steps. For BE valves although the undersizing but overfilling strategy sounds like a reasonable strategy in most cases, the study by Xuan et al 25 has conflicting results to make such a recommendation. As a matter of fact, SE valves do not have such an option as underfilling or overfilling.…”

“…According to the results of this study, undersizing but overfilling was related to decreased PVL and mean postprocedural transvalvular pressure gradient and reduced incidence of annular rupture. Conversely, Xuan et al 25 evaluated the impact of THV size on leaflet stress in patients with grey zone annulus and implanted ESXT valves. Leaflet stress is considered to be related to accelerated valve degeneration and shorter durability according to the previous reports.…”

Usability and accuracy of two different aortic annulus sizing software programs in patients undergoing transcatheter aortic valve replacement

“…Second, true valve size in patient 2 can only be approximately determined because measurements by expert group are between 2 TAVR sizes. Besides the fact that correct measurement between 2 TAVR sizes is subject of current research [ 32 ], a ICC of 0.981 is considered as an excellent degree of interrater reliability [ 33 ]. Third, the training-free interval between T1 and T2 differed in the minimum and in the maximum (minimum 13 days, maximum 22 days).…”

Prosthesis-patient mismatch in transcatheter and surgical aortic valve replacement

“…Flameng et al followed 664 SAVR patients for a median of 6.1 years and showed that PPM was independently associated with a 2.3-fold increase in the risk of SVD (35). This association may be related to higher mechanical leaflet stress in the setting of high flow rates and higher mechanical leaflet stress related to under-expansion of the valve (46)(47)(48).…”