scholarly journals A Design Framework of Unloaded Leaflet Shape for the Ovine Pulmonary Valve Single Leaflet Replacement Surgery

2011 ◽  
Vol 5 (2) ◽  
Author(s):  
Rong Fan ◽  
Christopher Hobson ◽  
Ahmed Bayoumi ◽  
John Mayer ◽  
William Wagner ◽  
...  
Keyword(s):  
Pulmonary Valve ◽  
Design Framework ◽  
Replacement Surgery ◽  
Leaflet Shape

Design of Tissue-Engineered Leaflet Shape for the Ovine Pulmonary Valve Single Leaflet Replacement Surgery

2011 ◽  
Author(s):  
Rong Fan ◽  
Christopher M. Hobson ◽  
Ahmed Bayoumi ◽  
John E. Mayer ◽  
William R. Wagner ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Pulmonary Valve ◽  
Fe Simulation ◽  
Somatic Growth ◽  
Initial Shape ◽  
Replacement Surgery ◽  
Anisotropic Mechanical Properties ◽  
The One ◽  
Leaflet Shape

Pulmonary valve (PV) replacement surgery is a treatment option for patients with a congenitally defective pulmonary outflow track. A tissue engineered pulmonary valve (TEPV) is a potential approach to serve as a replacement pediatric heart valve that has the potential for somatic growth. The single leaflet replacement surgical model can assist in assessing candidate biomaterials responses to in-vivo function. However, an empirically determined unloaded leaflet shape may result in abnormal valve function due to incomplete coaptation of leaflets and asymmetric stress distributions. Thus, to determine the final deformed shape of an engineered scaffold replacement PV leaflet under transvalvular pressure the following key factors must be determined: the scaffold anisotropic mechanical properties, optimal thickness, and the exact initial leaflet shape. We have used electrospun poly (ester urethane) ureas (ES-PEUU) scaffolds since they exhibit mechanical properties very similar to the native PV [1]. In this work we present a design framework of the optimal leaflet shape determination utilizing a single sheet of ES-PEUU for single leaflet replacement surgery via finite element (FE) simulation. The mechanical properties of ES-PEUU scaffold for leaflet replacement were obtained from biaxial in-plane tension and three-point bending flexural deformation experiments. Generalized Fung-type hyperelastic constitutive model [2] was implemented into a commercial FE software package to simulate the mechanical behavior of ES-PEUU scaffolds. By perturbing the initial shape of leaflet and simulating its quasi-static deformation under PV diastolic loading, the optimal shape of unloaded leaflet can be determined by comparing the deformed shape of leaflet obtained from FE simulation of TEPV with the one from microCT scan of a native ovine PV.

Optimization of Engineered Ovine Pulmonary Heart Valve Leaflet Tissue Shape for Single Leaflet Replacement

2012 ◽  
Author(s):  
Rong Fan ◽  
Michael S. Sacks ◽  
Ahmed Bayoumi ◽  
John E. Mayer ◽  
Christopher M. Hobson ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fe Simulation ◽  
Intermediate Step ◽  
In Vitro Test ◽  
Initial Shape ◽  
Replacement Surgery ◽  
Anisotropic Mechanical Properties ◽  
Leaflet Shape

Pulmonary valve (PV) replacement surgery is a treatment option for patients with a congenitally defective pulmonary outflow track. While a tissue engineered approach offers many potential advantages, develop of such a valve involves a complex process of optimization. As an intermediate step, we have used a single leaflet replacement surgical model to further our understanding of the in-vivo remodeling process. A critical step is to determine the deformed shape of the replacement PV leaflet under transvalvular pressure. Key factors in this process are: the scaffold anisotropic mechanical properties, optimal thickness, and the exact initial leaflet shape. We have used electrospun poly (ester urethane) ureas (ES-PEUU) scaffolds since they exhibit mechanical properties very similar to the native PV. In this work we present a design framework of the optimal leaflet shape determination utilizing a single sheet of ES-PEUU for single leaflet replacement surgery via finite element (FE) simulation. The mechanical properties of ES-PEUU scaffold for leaflet replacement were obtained from biaxial in-plane tension experiments. Generalized Fung-type hyperelastic constitutive model [1] was implemented into a commercial FE software package to simulate the deformation of ES-PEUU scaffolds under pressure. By perturbing the initial shape of leaflet and simulating its quasi-static deformation under PV diastolic loading, the optimal shape of unloaded leaflet was determined by comparing the deformed shape of leaflet obtained from FE simulation of TEPV with the one from microCT scan of a native ovine PV. In-vitro test of PV after single leaflet replacement was also conducted to validate the developed method.

scholarly journals Patient-Specific MRI-Based 3D FSI RV/LV/Patch Models for Pulmonary Valve Replacement Surgery and Patch Optimization

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Dalin Tang ◽  
Chun Yang ◽  
Tal Geva ◽  
Pedro J. del Nido
Keyword(s):  
Valve Replacement ◽  
Pulmonary Valve ◽  
Scar Tissue ◽  
Mechanical Analysis ◽  
Pulmonary Valve Replacement ◽  
Patient Specific ◽  
Fluid Structure Interactions ◽  
Replacement Surgery ◽  
Cardiac Functions ◽  
Before And After

A patient-specific right/left ventricle and patch (RV/LV/patch) combination model with fluid-structure interactions (FSIs) was introduced to evaluate and optimize human pulmonary valve replacement/insertion (PVR) surgical procedure and patch design. Cardiac magnetic resonance (CMR) imaging studies were performed to acquire ventricle geometry, flow velocity, and flow rate for healthy volunteers and patients needing RV remodeling and PVR before and after scheduled surgeries. CMR-based RV/LV/patch FSI models were constructed to perform mechanical analysis and assess RV cardiac functions. Both pre- and postoperation CMR data were used to adjust and validate the model so that predicted RV volumes reached good agreement with CMR measurements (error <3%). Two RV/LV/patch models were made based on preoperation data to evaluate and compare two PVR surgical procedures: (i) conventional patch with little or no scar tissue trimming, and (ii) small patch with aggressive scar trimming and RV volume reduction. Our modeling results indicated that (a) patient-specific CMR-based computational modeling can provide accurate assessment of RV cardiac functions, and (b) PVR with a smaller patch and more aggressive scar removal led to reduced stress/strain conditions in the patch area and may lead to improved recovery of RV functions. More patient studies are needed to validate our findings.

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