Dataset Information

Stent and Leaflet Stresses in 29-mm Second-Generation Balloon-Expandable Transcatheter Aortic Valve.

ABSTRACT: Equipoise of transcatheter aortic valve replacement with surgical aortic valve replacement in intermediate-risk patients has been demonstrated. As transcatheter aortic valve replacement usage expands, questions regarding long-term durability become paramount. Valve design impacts durability with regions of increased leaflet stress being vulnerable to early failure. However, transcatheter aortic valve (TAV) leaflet stresses are unknown. The objective of this study was to determine stent and leaflet stresses of second-generation balloon-expandable TAV.Commercial 29-mm Edwards Sapien XT (Edwards Lifesciences, Irvine, CA) valves underwent high-resolution microcomputed tomography scanning to develop precise three-dimensional geometric mesh. Compressed and uncompressed TAVs were modeled under systemic pressure using finite element software. Material properties of stent were based on cobalt-chromium, whereas those for leaflets were obtained from surgical bioprostheses.Maximum and minimum principal stresses on uncompressed Sapien XT TAV were 1.63 MPa and -0.36 MPa on leaflets and 93.3 MPa and -105.6 MPa on stent at diastolic pressure. Peak leaflet stress was observed at commissural tips where leaflets connected to the stent. For compressed TAV to 26 mm, maximum and minimum principal stresses were 1.55 MPa and -0.63 MPa on leaflets and 526.1 MPa and -902.2 MPa on stent at diastolic pressure. Peak leaflet stress was located at similar position and also along the suture line with the Dacron (C. R. Bard, Haverhill, PA).Stress analysis of two extreme deployed geometries of 29-mm Edwards Sapien XT using exact geometry from high-resolution scans demonstrated that peak stresses for TAV leaflets were present at commissural tips where leaflets were attached. These regions would be mostly likely to initiate degeneration.

SUBMITTER: Xuan Y

PROVIDER: S-EPMC5839641 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature

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Stent and Leaflet Stresses in 29-mm Second-Generation Balloon-Expandable Transcatheter Aortic Valve.

Xuan Yue Y Krishnan Kapil K Ye Jian J Dvir Danny D Guccione Julius M JM Ge Liang L Tseng Elaine E EE

The Annals of thoracic surgery 20170412 3

<h4>Background</h4>Equipoise of transcatheter aortic valve replacement with surgical aortic valve replacement in intermediate-risk patients has been demonstrated. As transcatheter aortic valve replacement usage expands, questions regarding long-term durability become paramount. Valve design impacts durability with regions of increased leaflet stress being vulnerable to early failure. However, transcatheter aortic valve (TAV) leaflet stresses are unknown. The objective of this study was to determ ...[more]

PMID: 28410636

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Project description:OBJECTIVE:Transcatheter aortic valve replacement is established therapy for high-risk and inoperable patients with severe aortic stenosis, but questions remain regarding long-term durability. Valve design influences durability. Increased leaflet stresses in surgical bioprostheses have been correlated with degeneration; however, transcatheter valve leaflet stresses are unknown. From 2007 to 2014, a majority of US patients received first-generation balloon-expandable transcatheter valves. Our goal was to determine stent and leaflet stresses in this valve design using finite element analyses. METHODS:A 26-mm Sapien Transcatheter Heart Valve (Edwards Lifesciences, Inc, Irvine, Calif) underwent high-resolution microcomputed tomography scanning to develop precise 3-dimensional geometry of the leaflets, the stent, and the polyethylene terephthalate elements. The stent was modeled using 3-dimensional elements and the leaflets were modeled using shell elements. Stent material properties were based on stainless steel, whereas those for leaflets were obtained from surgical bioprostheses. Noncylindrical Sapien valve geometry was also simulated. Pressure loading to 80 mm Hg and 120 mm Hg was performed using ABAQUS finite element software (Dassault Systèmes, Waltham, Mass). RESULTS:At 80 mm Hg, maximum principal stresses on Sapien leaflets were 1.31 megaspascals (MPa). Peak leaflet stress was observed at commissural tips where leaflets connected to the stent. Maximum principal stresses for the stent were 188.91 MPa and located at stent tips where leaflet commissures were attached. Noncylindrical geometry increased peak principal leaflet stresses by 16%. CONCLUSIONS:Using exact geometry from high-resolution scans, the 26-mm Sapien Transcatheter Heart Valve showed that peak stresses for both stent and leaflets were present at commissural tips where leaflets were attached. These regions would be prone to leaflet degeneration. Understanding stresses in first-generation transcatheter valves allows comparison to future designs for relative durability.

Project description:BackgroundCoronary obstruction during transcatheter aortic valve replacement (TAVR) is a rare, yet life-threatening, complication. The routine use of left main (LM) protection with or without stent placement in high-risk patients remains controversial. The aim of this study was to evaluate the outcomes of LM protection during TAVR and identify anatomic factors associated with need for stent placement.MethodsWe retrospectively reviewed all TAVR cases (native and valve-in-valve) performed in our institution between 2014 and 2019 and identified patients who underwent LM protection with a coronary wire, balloon, and/or stent during the procedure. We compared the pre-TAVR computed tomography aortic root characteristics, procedural data, short-, and long-term outcomes among the patients who eventually received an LM stent and those who did not.ResultsAmong 1925 TAVR patients, 41 (2.1%) underwent LM protection, and 10 of them (25%) had eventually a stent placed in the LM for threatened obstruction after valve deployment. In the native TAVR group (n = 35), 8 patients underwent LM stenting. A larger TAVR prosthesis, larger annular circumference (83.8 vs 76.1 mm; P = .038), lower ratio of sinotubular junction diameter to prosthesis size (1.02 vs 1.11; P = .032), and longer left coronary cusp (15.1 vs 13.9 mm; P = .18) were associated with higher incidence of LM stenting. In the valve-in-valve TAVR group (n = 6), 5 patients had a valve-to-coronary distance of less than 4 mm, and 2 of them received an LM stent. Both stent and nonstent groups had excellent outcomes with no major adverse cardiovascular events or coronary obstruction at 30 days. After a median follow-up of 351 days, 4 patients died (9.7%) (1 in the stent and 3 in the nonstent group), without any cases of late coronary obstruction or percutaneous coronary intervention in either group.ConclusionsLM protection with a coronary guidewire, balloon, or stent is a safe and effective method of coronary protection during TAVR in appropriately selected high-risk patients. Annular circumference, prosthesis size, left coronary cusp length, LM ostial height, and ratio of sinotubular junction to prosthesis size are important predictors of stent deployment.

Dataset Information

Stent and Leaflet Stresses in 29-mm Second-Generation Balloon-Expandable Transcatheter Aortic Valve.

Publications

Stent and Leaflet Stresses in 29-mm Second-Generation Balloon-Expandable Transcatheter Aortic Valve.

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