Synthetic fiber reinforced heart valves

Citation for published version (APA):Cacciola, G., Peters, G. W. M., Schreurs, P. J. G., & Baaijens, F. P. T. (1998). Synthetic fiber reinforced heartvalves. Poster session presented at Mate Poster Award 1998 : 3rd Annual Poster Contest, .

Document status and date:Published: 01/01/1998

Document Version:Accepted manuscript including changes made at the peer-review stage

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Download date: 18. Mar. 2021

Synthetic fiber reinforced heart valvesG. Cacciola, G. Peters, P. Schreurs, F. Baaijens

Eindhoven University of Technology,Faculty of Mechanical Engineering,

P.O. Box 513, NL 5600 MB Eindhovene-mail giovanna@wfw.wtb.tue.nl

Introduction

Commercially available heart valve prostheses are ei-ther mechanical or biological. Both mechanical andbiological valves are not optimal. Synthetic valvesare the future valve generation. However the proto-types made up to now have still durability problems.It is believed that considerable improvement can beachieved by using fiber reinforced composite materialfor the leaflets.

Materials and Manufacturing

The stented three-leaflets valve prosthesis (fig. 1a)consists of a stent, which supports the three leaflets.The leaflets are made of a flexible, fiber reinforced,synthetic material. In the stentless prototype (fig. 1b)the leaflets are directly made inside a piece of theaorta.

(a) (b)

fig. 1 Stented (a) and stentless (b) prototypes

The matrix (EPDM rubber) is reinforced with polyethy-lene (PE) fibers, which are thin and strong. The PEfibers are placed on the EPDM rubber, using a com-puter controlled winding machine. Different fiber lay-outs are possible in order to reinforce the compositematerial in the areas where the highest stresses oc-cur.

Numerical simulations

In the design, extensive use is made of a finite ele-ment model of the valve. The leaflets (and the aorta inthe stentless model) are subdivided into a large num-ber of elements, with the appropriate material behav-ior. The finite element models are shown in fig. 2.

The numerical simulation not only gives us the geom-etry of the leaflets during the cardiac cycle, but alsothe strains and stresses in the material. These re-sults are used to optimize the fiber layout such thatthe stresses in the leaflets will be as low as possible.

Y

X

Z

5.332e-05

3.334e-02

6.663e-02

9.992e-02

1.332e-01

1.665e-01

1.998e-01

2.331e-01

2.664e-01

2.996e-01

3.329e-01

1

Y X

Z 0.000e+00

2.500e-02

5.000e-02

7.500e-02

1.000e-01

1.250e-01

1.500e-01

1.750e-01

2.000e-01

2.250e-01

2.500e-01

1

fig. 2 Stented (left) and stentless (right) models

In fig. 3 the deformation of the models is comparedwith the motion of two prototypes. The openingand closing behavior was experimentally studied ina pulse duplicator system. A high speed camera wasused to record the valve motion.

Y

X

Z

1

X

Y

Z

1

(a) (d)(b) (c)

fig. 3 Stented and stentless models (a and c)and prototypes (b and d)

Conclusions

The procedure of manufacturing a three-leaflet valveprosthesis, with fiber reinforced leaflet, is very flexible.It is possible to apply the fibers so that the same func-tionality as in the natural valve is obtained. Prototypesof valves have been tested, showing good openingand closing behavior. FEM models with fiber rein-forcement show lower stresses than the model with-out fibers.