Biomedical Engineering Reference
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at high vs. low pressure. 65 The study revealed a lower rate of structural valve
deterioration in the low pressure fi xation group. Patient age at implantation
proved to be another important determinant of valve durability; valve
deterioration was lower in patients over 65 years old.
Jamieson et al. 66 reported on a series of 1823 CE supra-annular aortic
porcine implants with a 20 year follow-up. The overall actuarial survival was
28.8
2.0% at 20 years. The overall freedom
from structural valve deterioration in all age groups was 64% at 18 years,
but in patients
±
1.5% at 15 years and 6.8
±
70 years of age was even higher, 95%, at 18 year
follow-up.
4.4.4 Medtronic Mosaic porcine bioprosthesis
The Medtronic Mosaic porcine bioprosthesis (Fig. 4.11) represents the third
generation of the Porcine Hancock Bioprosthesis, and evolved after mul-
tiple refi nements to improve its function and durability. The use of amino-
oleic acid, an anti-mineralization agent, and low pressure fi xation with
glutaraldehyde has helped to preserve the collagen structure of the leafl ets.
The valve is mounted on a fl exible homopolymer stent that decreases the
commissural stress during valve closure. The sewing ring for the aortic posi-
tion has a scalloped shape that facilitates supra-annular valve implantation.
Both the aortic and mitral Medtronic valves have lower profi les than the
older Hancock valve.
￿ ￿ ￿ ￿ ￿
4.11 Medtronic Mosaic porcine prosthesis, the third generation of the
Hancock porcine tissue valve. Image presented with permission of
Medtronic, Inc., Minneapolis, MN, USA.
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