Textile valves in vitro performance

In order to test the textile prototype in vitro, the shaped tubular textile membrane was assembled with a ring taken from a Mitroflow 

Regarding dynamic regurgitation, Fig. 16.14 shows that the values are globally in the range of values obtained for the reference valves tested. The 

Finally, from a strictly qualitative point of view, the movement of the valve leaflets was studied using a video camera. Pictures were taken from the valve in closed and open positions (Fig. 16.16). In the closed position, it can be observed that the three cusps come together with good coaptation. In the open position, the flexibility of the cusps induces low flow resistance. As to the free-edge curvature, it inverts easily from closed to open position. 

The early in vitro results of the textile valve prototype show that the device is functional under physiological pressure and flow conditions. The performances obtained are in the range of what is obtained with other commercially available valves, and could be improved by varying the fabric construction parameters. 

3 Influence of the fabric construction parameters on valve behavior 

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The crucial role of the heart in serving as the pump to maintain a continuous blood supply to all the organs of the body depends on flexible heart valve leaflets that need to cycle back and forth with each beat of the heart. This occurs about 100,000 times each day and places exceptionally high demand on the bending fatigue performance of a prosthetic heart valve material, which should yet be required to last some minimum number of years. The development of a percutaneously delivered textile based heart valve with flexible and fatigue resistant leaflets is described in Chapter 16. This prototype under development shows promise based on the in vitro fatigue work and animal trials aheady conducted. 

Abstract This chapter discusses the potential of textiles used as heart valve leaflet replacement material. The chapter first reviews the anatomy of the aortic valve, before describing the diseases the valve may undergo and the limits of the noninvasive technologies available to replace the faulty valve. It then presents textile valve manufacture, and the performance that can be obtained in vitro in both the short and long term. Early animal in vivo results are presented in the last section. 

Parallel research by Lloyd (Lloyd and Singer,2001) led to the manufacture and in vitro testing of a knitted polyester valve. Although no quantitative results have been published about the performances of this device, the authors report in a qualitative way that the textile valve is functional. The work reported by Heim et aL represents the most advanced results on textile valves that can be found in the scientific literature to date. In the following sections we present a synthesis of that research activity. 

Heim F, Durand B and Chakfe N (2005), Textile heart valve prosthesis Influence of the fabric parameters on its hydrodynamic performance in vitro , Comput Methods Biomech Biomed Engin, 1,137-138. 

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