What is the clinical evidence from this study?

Study design: Other. Population: Aortic stenosis and Regurgitation. Intervention: Novel Nitinol Aortic Valve Stent. Primary outcome: Fatigue life (mean and amplitude strains).

September 1, 2023Open Access

Fatigue Analysis of Novel Aortic Valve Stent Using Finite Element Analysis

RKRajesh KandulaJawaharlal Nehru Technological University, Hyderabad KBKarthik BujuruUniversity of Colorado Boulder

Key Result

Finite element analysis of a novel Nitinol aortic valve stent demonstrated that 99.97% of the stent frame integration points survived 10^7 cycles of simulated fatigue loading.

Structured PICO

Population

Computational model of a novel Nitinol-based prosthetic aortic valve stent (33mm outer diameter) deployed in an aneurysmal aortic root model (30mm annulus).

Intervention

Finite element analysis (FEA) simulating deployment and 3 cycles of systolic (40 mmHg) and diastolic (144 mmHg) physiological loading.

Outcome

Fatigue life estimation using mean and amplitude strains plotted on a constant-life diagram.surrogate

Finite element analysis using a constant-life diagram provides a relatively inexpensive preliminary method to identify high-strain areas in novel transcatheter aortic valve stent designs prior to physical fatigue testing.

Limitations

Lack of representation of electropolishing and deburring of edges in the FEA model
Fatigue life prediction using FEA and constant-life diagram based on generic diamond data may not be accurate
Thermal and mechanical stress profiles from specific fabrication processes may not be accurately represented in the FEA model

Abstract

Aortic stenosis and Regurgitation are the common heart valve diseases that about 20% of the US population get diagnosed with each year. Recent advances in minimally invasive surgical techniques like transcatheter aortic valve replacement (TAVR) have paved the way for high-risk patient treatment with minimal hospital stay and use of anesthetic. While the patient data on prosthetic stent based aortic valve durability from the last decade has instilled confidence, this data is still considered inadequate for large scale adoption of TAVR therapy for low and medium risk patients. As one of the leading failure modes for the Nitinol based prosthetic stents is material fracture due to cycling fatigue, it is critical to identify a method to accurately predict it. While the historic scientific literature available indicates the presence of stress based, strain based and damage-tolerance analysis-based assessments of fatigue behavior of Nitinol material, there still exists a gap specifically for accurate prediction of fatigue life of Nitinol based prosthetic stents using computational methods like finite element analysis. This article presents a case study of estimating the fatigue life of novel aortic valve when subjected to physiological loading conditions using FEA while using minimal computational resources. This FEA and strain-based approach using constant-life diagram method of fatigue estimation will allow for preliminary evaluation of fatigue life and make design and process changes before fabrication and testing of prosthetic aortic.

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