Impact of Clinically Relevant Elliptical Deformations on the Damage Patterns of Sagging and Stretched Leaflets in a Bioprosthetic Heart Valve

Deepa Sritharan; Parinaz Fathi; Jason D Weaver; Stephen M Retta; Changfu Wu; Nandini Duraiswamy

doi:10.1007/s13239-018-0366-x

Impact of Clinically Relevant Elliptical Deformations on the Damage Patterns of Sagging and Stretched Leaflets in a Bioprosthetic Heart Valve

Cardiovasc Eng Technol. 2018 Sep;9(3):351-364. doi: 10.1007/s13239-018-0366-x. Epub 2018 Jun 12.

Authors

Deepa Sritharan¹, Parinaz Fathi¹, Jason D Weaver¹, Stephen M Retta¹, Changfu Wu², Nandini Duraiswamy³

Affiliations

¹ Division of Applied Mechanics (DAM), Office of Science and Engineering Laboratories (OSEL), Center for Devices and Radiological Health (CDRH), Food and Drug Administration (FDA), 10903 New Hampshire Avenue, WO62, #2206, Silver Spring, MD, 20993, USA.
² Division of Cardiovascular Devices (DCD), Office of Device Evaluation (ODE), Center for Devices and Radiological Health (CDRH), Food and Drug Administration (FDA), 10903 New Hampshire Avenue, Silver Spring, MD, 20993, USA.
³ Division of Applied Mechanics (DAM), Office of Science and Engineering Laboratories (OSEL), Center for Devices and Radiological Health (CDRH), Food and Drug Administration (FDA), 10903 New Hampshire Avenue, WO62, #2206, Silver Spring, MD, 20993, USA. nandini.duraiswamy@fda.hhs.gov.

Abstract

After implantation of a transcatheter bioprosthetic heart valve its original circular circumference may become distorted, which can lead to changes in leaflet coaptation and leaflets that are stretched or sagging. This may lead to early structural deterioration of the valve as seen in some explanted transcatheter heart valves. Our in vitro study evaluates the effect of leaflet deformations seen in elliptical configurations on the damage patterns of the leaflets, with circular valve deformation as the control. Bovine pericardial tissue heart valves were subjected to accelerated wear testing under both circular (N = 2) and elliptical (N = 4) configurations. The elliptical configurations were created by placing the valve inside custom-made elliptical holders, which caused the leaflets to sag or stretch. The hydrodynamic performance of the valves was monitored and high resolution images were acquired to evaluate leaflet damage patterns over time. In the elliptically deformed valves, sagging leaflets experienced more damage from wear compared to stretched leaflets; the undistorted leaflets of the circular valves experienced the least leaflet damage. Free-edge thinning and tearing were the primary modes of damage in the sagging leaflets. Belly region thinning was seen in the undistorted and stretched leaflets. Leaflet and fabric tears at the commissures were seen in all valve configurations. Free-edge tearing and commissure tears were the leading cause of valve hydrodynamic incompetence. Our study shows that mechanical wear affects heart valve pericardial leaflets differently based on whether they are undistorted, stretched, or sagging in a valve configuration. Sagging leaflets are more likely to be subjected to free-edge tear than stretched or undistorted leaflets. Reducing leaflet stress at the free edge of non-circular valve configurations should be an important factor to consider in the design and/or deployment of transcatheter bioprosthetic heart valves to improve their long-term performance.

Keywords: Bioprosthetic heart valve; Leaflet durability; Non-circular deformation; Pericardial tissue; Valve fatigue.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.
Research Support, U.S. Gov't, P.H.S.

MeSH terms

Animals
Bioprosthesis*
Cardiac Catheterization / adverse effects
Cardiac Catheterization / instrumentation*
Cardiac Catheterization / methods
Cattle
Equipment Failure Analysis
Heart Valve Prosthesis Implantation / adverse effects
Heart Valve Prosthesis Implantation / instrumentation*
Heart Valve Prosthesis Implantation / methods
Heart Valve Prosthesis*
Hemodynamics*
Hydrodynamics
Materials Testing
Pericardium / transplantation*
Prosthesis Design
Prosthesis Failure*
Stress, Mechanical
Tensile Strength

Grants and funding

FD999999/ImFDA/Intramural FDA HHS/United States