Biomedical Engineering Reference
In-Depth Information
4.6 Strut fracture of a Björk-Shiley valve prosthesis. The extruded
pyrolyte convexo-concave disc and the outfl ow strut were recovered
at surgery.
4.7 Medtronic-Hall tilting valve prosthesis, viewed from the infl ow
aspect. Image presented with permission of Medtronic, Inc.,
Minneapolis, MN, USA.
￿ ￿ ￿ ￿ ￿
With the subsequent introduction and mounting popularity of bileafl et
valves, the demand for tilting valve prostheses declined. The only remain-
ing tilting disc prosthesis in current use is the Medtronic-Hall (Medtronic
Inc., Minneapolis, MN), which was initially introduced as the Hall-Kaster
valve in 1976 (Fig. 4.7). The valve entered clinical use in Oslo, Norway, in
1977, and was approved for commercial distribution in the United States
in December 1981. The valve is machined from a single piece of titanium,
with no welds, and contains a rotatable sewing cuff. The disc is made of
tungsten-impregnated graphite, which renders the disc radiopaque, with a
pyrolytic carbon coating. The disc opens 75° in the aortic and 70° in the
Search WWH ::




Custom Search