Comparative Fluid–Structure Interaction Analysis of Polymeric Transcatheter and Surgical Aortic Valves' Hemodynamics and Structural Mechanics

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Ram P. Ghosh ◽  
Gil Marom ◽  
Oren M. Rotman ◽  
Marvin J. Slepian ◽  
Saurabh Prabhakar ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Aortic Valve Replacement ◽  
Valve Replacement ◽  
Fluid Structure Interaction ◽  
Effective Orifice Area ◽  
Shear Stresses ◽  
Predictive Tool ◽  
Orifice Area ◽  
Fluid Structure ◽  
Structure Interaction

Transcatheter aortic valve replacement (TAVR) has emerged as an effective alternative to conventional surgical aortic valve replacement (SAVR) in high-risk elderly patients with calcified aortic valve disease. All currently food and drug administration approved TAVR devices use tissue valves that were adapted to but not specifically designed for TAVR use. Emerging clinical evidence indicates that these valves may get damaged during crimping and deployment—leading to valvular calcification, thrombotic complications, and limited durability. This impedes the expected expansion of TAVR to lower-risk and younger patients. Viable polymeric valves have the potential to overcome such limitations. We have developed a polymeric SAVR valve, which was optimized to reduce leaflet stresses and offer a thromboresistance profile similar to that of a tissue valve. This study compares the polymeric SAVR valve's hemodynamic performance and mechanical stresses to a new version of the valve—specifically designed for TAVR. Fluid–structure interaction (FSI) models were utilized and the valves' hemodynamics, flexural stresses, strains, orifice area, and wall shear stresses (WSS) were compared. The TAVR valve had 42% larger opening area and 27% higher flow rate versus the SAVR valve, while WSS distribution and mechanical stress magnitudes were of the same order, demonstrating the enhanced performance of the TAVR valve prototype. The TAVR valve FSI simulation and Vivitro pulse duplicator experiments were compared in terms of the leaflets' kinematics and the effective orifice area. The numerical methodology presented can be further used as a predictive tool for valve design optimization for enhanced hemodynamics and durability.

scholarly journals Image-Guided Fluid-Structure Interaction Simulation of Transvalvular Hemodynamics: Quantifying the Effects of Varying Aortic Valve Leaflet Thickness

Fluids ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 119 ◽  
Author(s):  
Anvar Gilmanov ◽  
Alexander Barker ◽  
Henryk Stolarski ◽  
Fotis Sotiropoulos
Keyword(s):  
Blood Flow ◽  
Aortic Valve ◽  
Heart Valve ◽  
Fluid Structure Interaction ◽  
Maximum Velocity ◽  
Patient Specific ◽  
Hemodynamic Parameters ◽  
Orifice Area ◽  
Fluid Structure ◽  
Structure Interaction

When flow-induced forces are altered at the blood vessel, maladaptive remodeling can occur. One reason such remodeling may occur has to do with the abnormal functioning of the aortic heart valve due to disease, calcification, injury, or an improperly-designed prosthetic valve, which restricts the opening of the valve leaflets and drastically alters the hemodynamics in the ascending aorta. While the specifics underlying the fundamental mechanisms leading to changes in heart valve function may differ from one cause to another, one common and important change is in leaflet stiffness and/or mass. Here, we examine the link between valve stiffness and mass and the hemodynamic environment in aorta by coupling magnetic resonance imaging (MRI) with high-resolution fluid–structure interaction (FSI) computational fluid dynamics to simulate blood flow in a patient-specific model. The thoracic aorta and a native aortic valve were re-constructed in the FSI model from the MRI data and used for the simulations. The effect of valve stiffness and mass is parametrically investigated by varying the thickness (h) of the leaflets (h = 0.6, 2, 4 mm). The FSI simulations were designed to investigate systematically progressively higher levels of valve stiffness by increasing valve thickness and quantifying hemodynamic parameters known to be linked to aortopathy and valve disease. The computed results reveal dramatic differences in all hemodynamic parameters: (1) the geometric orifice area (GOA), (2) the maximum velocity V max of the jet passing through the aortic orifice area, (3) the rate of energy dissipation E ˙ diss ( t ) , (4) the total loss of energy E diss , (5) the kinetic energy of the blood flow E kin ( t ) , and (6) the average magnitude of vorticity Ω a ( t ) , illustrating the change in hemodynamics that occur due to the presence of aortic valve stenosis.

scholarly journals The fallacy of indexed effective orifice area charts to predict prosthesis–patient mismatch after prosthesis implantation

2020 ◽  
Vol 21 (10) ◽  
pp. 1116-1122 ◽  
Author(s):  
Michiel D Vriesendorp ◽  
Rob A F De Lind Van Wijngaarden ◽  
Stuart J Head ◽  
Arie-Pieter Kappetein ◽  
Graeme L Hickey ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Aortic Valve Replacement ◽  
Valve Replacement ◽  
Reference Values ◽  
Effective Orifice Area ◽  
Training Set ◽  
Surgical Aortic Valve Replacement ◽  
Test Set ◽  
Orifice Area ◽  
Normal Reference

Abstract Aims  Indexed effective orifice area (EOAi) charts are used to determine the likelihood of prosthesis–patient mismatch (PPM) after aortic valve replacement (AVR). The aim of this study is to validate whether these EOAi charts, based on echocardiographic normal reference values, can accurately predict PPM. Methods and results  In the PERIcardial SurGical AOrtic Valve ReplacemeNt (PERIGON) Pivotal Trial, 986 patients with aortic valve stenosis/regurgitation underwent AVR with an Avalus valve. Patients were randomly split (50:50) into training and test sets. The mean measured EOAs for each valve size from the training set were used to create an Avalus EOAi chart. This chart was subsequently used to predict PPM in the test set and measures of diagnostic accuracy (sensitivity, specificity, and negative and positive predictive value) were assessed. PPM was defined by an EOAi ≤0.85 cm2/m2, and severe PPM was defined as EOAi ≤0.65 cm2/m2. The reference values obtained from the training set ranged from 1.27 cm2 for size 19 mm up to 1.81 cm2 for size 27 mm. The test set had an incidence of 66% of PPM and 24% of severe PPM. The EOAi chart inaccurately predicted PPM in 30% of patients and severe PPM in 22% of patients. For the prediction of PPM, the sensitivity was 87% and the specificity 37%. For the prediction of severe PPM, the sensitivity was 13% and the specificity 98%. Conclusion  The use of echocardiographic normal reference values for EOAi charts to predict PPM is unreliable due to the large proportion of misclassifications.

scholarly journals Impact of the indexed effective orifice area on mid-term cardiac-related mortality after aortic valve replacement

Heart ◽  
2010 ◽  
Vol 96 (11) ◽  
pp. 865-871 ◽  
Author(s):  
S. Bleiziffer ◽  
A. Ali ◽  
I. M. Hettich ◽  
D. Akdere ◽  
R. P. Laubender ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Aortic Valve Replacement ◽  
Valve Replacement ◽  
Effective Orifice Area ◽  
Orifice Area ◽  
Related Mortality

Accuracy of Industry Generated Effective Orifice Area Calculators for Aortic Valve Replacement

2012 ◽  
Vol 21 ◽  
pp. S274
Author(s):  
J. Chan ◽  
P. Naidu ◽  
A. Cheng ◽  
J. Kumar ◽  
A. Appelbe ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Aortic Valve Replacement ◽  
Valve Replacement ◽  
Effective Orifice Area ◽  
Orifice Area
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