Transcatheter fiber heart valve: Effect of crimping on material performances

Abstract

Transcatheter aortic valve implantation (TAVI) has become a popular alternative technique to surgical valve replacement. However, the biological valve tissue used in these devices appears to be fragile material in the long term particularly due being folded for low diameter catheter insertion purposes and when released in a calcified environment with irregular geometry. Textile polyester material is characterized by outstanding folding and strength properties combined with proven biocompatibility. It could therefore be considered as a replacement for biological valve leaflets in the TAVI procedure. The folding process associated with crimping, however, may degrade the filaments involved in the fibrous assembly and limit the durability of the device. The purpose of the present work is to study the effect of different crimping conditions on the mechanical performances of textile valve prototypes made from various fabric constructions. Results show that crimping generates some creases in the fabrics, which surface topography varies with fabric construction and crimping configuration. The mechanical properties of the crimped materials are globally slightly reduced. To determine how critical the modifications due to crimping are for prosthesis durability, more detailed long term in vitro and in vivo trials with crimped textile prototypes are needed in addition to this preliminary work.

Mechanical degradation of biological heart valve tissue induced by low diameter crimping: An early assessment

“…The advantage of the trans-femoral approach is the need for only light anesthesia for the patient compared to the trans-apical approach. In a previous work, Heim et al studied already the mechanical degradations undergone by synthetic valves crimped to low diameter values (Khoffi et al, 2014). They compressed valve prototypes made from polyester textile material to 1 mm diameter and studied the mechanical damage that occurred in the leaflets.…”

On the Mechanics of Transcatheter Aortic Valve Replacement

“…Most of these studies that rely on the histology of pericardial leaflets 20, 63, 156 have credibly documented that mechanical stresses applied to pericardial leaflets result in disruption of their collagen fibers’ natural patterns, and may lead to calcification and early valve problem. 62, 111, 156 The results of a more recent study published in the New England Journal of Medicine by Makkar et al indicate that transcatheter aortic valves may lead to subclinical leaflet thrombosis based on the results from PORTICO IDE trial in comparison to SAVORY and RESOLVE registries. 78 A potential mechanism could be the injured rough surface of the leaflet facilitating thrombus formation.…”

Transcatheter Heart Valve Crimping and Expansion: Commentary

“…All the more recent PU polymers selected for percutaneous devices might display the same weaknesses as the devices of the early 1970s: thrombosis, calcification, degradation [38]. The valves with leaflets made of woven polyester fabrics show an interesting durability so long as the risk of fraying at their edges is kept under control [39]. However, the in vivo healing of polyester fabric is unpredictable with sequences of encapsulation, fibrinolysis, thrombotic accumulation and possibly embolization [40].…”