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Surgical reconstruction of semilunar valves in the growing child: Should we mimic the venous valve? A simulation study.

ABSTRACT: OBJECTIVES:Neither heart valve repair methods nor current prostheses can accommodate patient growth. Normal aortic and pulmonary valves have 3 leaflets, and the goal of valve repair and replacement is typically to restore normal 3-leaflet morphology. However, mammalian venous valves have bileaflet morphology and open and close effectively over a wide range of vessel sizes. We propose that they might serve as a model for pediatric heart valve reconstruction and replacement valve design. We explore this concept using computer simulation. METHODS:We use a finite element method to simulate the ability of a reconstructed cardiac semilunar valve to close competently in a growing vessel, comparing a 3-leaflet design with a 2-leaflet design that mimics a venous valve. Three venous valve designs were simulated to begin to explore the parameter space. RESULTS:Simulations show that for an initial vessel diameter of 12 mm, the venous valve design remains competent as the vessel grows to 20 mm (67%), whereas the normal semilunar design remains competent only to 13 mm (8%). Simulations also suggested that systolic function, estimated as effective orifice area, was not detrimentally affected by the venous valve design, with all 3 venous valve designs exhibiting greater effective orifice area than the semilunar valve design at a given level of vessel growth. CONCLUSIONS:Morphologic features of the venous valve design make it well suited for competent closure over a wide range of vessel sizes, suggesting its use as a model for semilunar valve reconstruction in the growing child.

SUBMITTER: Hammer PE

PROVIDER: S-EPMC5250537 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature

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Surgical reconstruction of semilunar valves in the growing child: Should we mimic the venous valve? A simulation study.

Hammer Peter E PE Roberts Erin G EG Emani Sitaram M SM Del Nido Pedro J PJ

The Journal of thoracic and cardiovascular surgery 20160831 2

<h4>Objectives</h4>Neither heart valve repair methods nor current prostheses can accommodate patient growth. Normal aortic and pulmonary valves have 3 leaflets, and the goal of valve repair and replacement is typically to restore normal 3-leaflet morphology. However, mammalian venous valves have bileaflet morphology and open and close effectively over a wide range of vessel sizes. We propose that they might serve as a model for pediatric heart valve reconstruction and replacement valve design. W ...[more]

PMID: 27665220

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Project description:BACKGROUND:The structure of the valve leaflets and sinuses are crucial in supporting the proper function of the semilunar valve and ensuring leaflet durability. Therefore, an enhanced understanding of the structural characteristics of the semilunar valves is fundamental to the evaluation and staging of semilunar valve pathology, as well as the development of prosthetic or bioprosthetic valves. This paper illustrates the process of combining computer-aided design (CAD), 3D printing and flow assessment with 4-dimensional flow magnetic resonance imaging (MRI) to provide detailed assessment of the structural and hemodynamic characteristics of the normal semilunar valve. METHODS:Previously published geometric data on the aortic valve was used to model the 'normal' tricuspid aortic valve with a CAD software package and 3D printed. An MRI compatible flow pump with the capacity to mimic physiological flows was connected to the phantom. A peak flow rate of 100?mL/s and heart rate of 60 beats per minute were used. MRI measurements included cine imaging, 2D and 4D phase-contrast imaging to assess valve motion, flow velocity and complex flow patterns. RESULTS:Cine MRI data showed normal valve function and competency throughout the cardiac cycle in the 3D-printed phantom. Quantitative analysis of 4D Flow data showed net flow through 2D planes proximal and distal to the valve were very consistent (26.03?mL/s and 26.09?mL/s, respectively). Measurements of net flow value agreed closely with the flow waveform provided to the pump (27.74?mL/s), confirming 4D flow acquisition in relation to the pump output. Peak flow values proximal and distal to the valve were 78.4?mL/s and 63.3?mL/s, respectively. Particle traces of flow from 4D-phase contrast MRI data demonstrated flow through the valve into the ascending aorta and vortices within the aortic sinuses, which are expected during ventricular diastole. CONCLUSION:In this proof of concept study, we have demonstrated the ability to generate physiological 3D-printed aortic valve phantoms and evaluate their function with cine- and 4D Flow MRI. This technology can work synergistically with promising tissue engineering research to develop optimal aortic valve replacements, which closely reproduces the complex function of the normal aortic valve.

Project description:Background: Valve-in-Valve transcatheter aortic valve implantation (ViV-TAVI) is a growing alternative for redo-surgery in patients with degenerated surgical valves. To our knowledge, data are lacking on the determinants on ViV-TAVI procedural success in patients with degenerated surgical valves. Methods: All consecutive patients undergoing ViV-TAVI for degenerated surgical valves at the Cleveland Clinic were analyzed. Data were extracted from our patient registry on baseline patient characteristics, echocardiographic parameters, and procedural details. To identify possible predictors of ViV-TAVI procedural success, we employed a multivariate logistic regression model. Results: A total of 186 patients who underwent ViV-TAVI were analyzed, with procedural success (VARC-2 device success and absence of periprocedural MACCE) reported in 165 (88.7%) patients. Patients with successful ViV-TAVI were significantly younger and had more frequent utilization of the transfemoral access than those with failed procedure. Other baseline and procedural characteristics were comparable between both groups. In terms of echocardiographic parameters, the procedural success group had a significantly lower AV peak pressure gradient (62.1 ± 24.7 vs. 74.1 ± 34.6 mmHg; p = 0.04) and lower incidence of moderate-to-severe aortic regurgitation [AR] (30.4 vs. 55%; p = 0.04). However, no significant differences between both groups were noted in terms of AV mean pressure gradient and left ventricular measurements. In multivariate analysis, lower AV peak pressure gradient (OR = 0.97, 95% CI: 0.95-0.99) and absence of moderate-to-severe AR (OR = 0.65, 95% CI: 0.44-0.95) at baseline emerged as independent predictors of ViV-TAVI procedural success. Conclusion: Valve-in-Valve TAVI for degenerated surgical valves is a feasible approach with high success rates, especially in those with lower AV peak pressure gradient and absence of moderate-to-severe AR. Studies with larger sample size and longer follow-up are required to further characterize the predictors of ViV-TAVI success and other clinical outcomes.

Project description:Background Transcatheter aortic valve replacement with supra-annular transcatheter heart valves has been adopted in patients with degenerated surgical aortic valves. The next generation self-expanding Evolut PRO valve has not been evaluated in patients with surgical valve failure. Methods and Results Patients undergoing transcatheter aortic valve replacement in degenerated surgical aortic valve procedures using the Evolut R or Evolut PRO transcatheter heart valves in the Society of Thoracic Surgeons and American College of Cardiology Transcatheter Valve Therapy Registry between April 2015 and June 2019 were evaluated. Transcatheter valve performance was evaluated by clinical site echocardiography. In-hospital, 30-day, and 1-year clinical outcomes were based on the Society of Thoracic Surgeons-American College of Cardiology-Transcatheter Valve Therapy registry definitions. Transcatheter aortic valve replacement in degenerated surgical aortic valve was performed in 5897 patients (5061 [85.8%] patients received the Evolut R valve and 836 [14.2%] received the Evolut PRO valve). Thirty-day transcatheter heart valves hemodynamic performance was excellent in both groups (mean gradient: Evolut PRO: 13.8±7.5 mm Hg; Evolut R: 14.5±8.1 mm Hg), while paravalvular regurgitation was significantly different between valve types (P=0.02). Clinical events were low at 30 days (Evolut PRO: for the all-cause mortality, 2.8%, any stroke was 1.8%, new pacemaker implantation, 3.0%: Evolut R:all-cause mortality, 2.5%, any stroke was 2.2%, new pacemaker implantation, 5.3%) and 1 year (Evolut PRO: all-cause mortality, 9.2%; any stroke, 3.1%; Evolut R: all-cause mortality, 9.8%; any stroke, 2.9%). Conclusions Transcatheter aortic valve replacement in degenerated surgical aortic valve with self-expandable supra-annular transcatheter heart valves is associated with excellent clinical outcomes and valve hemodynamics. Additional reductions in residual paravalvular regurgitation were obtained with the next generation Evolut PRO.

Dataset Information

Surgical reconstruction of semilunar valves in the growing child: Should we mimic the venous valve? A simulation study.

Publications

Surgical reconstruction of semilunar valves in the growing child: Should we mimic the venous valve? A simulation study.

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