Biomedical Engineering Reference
In-Depth Information
4.8
St. Jude Medical bileafl et Regent series valve prosthesis. Image
courtesy of St. Jude Medical, St. Paul, MN, USA.
Recently, early results were reported from 300 Regent aortic valve
implants in a multicenter clinical trial in Europe and Canada. Excellent
clinical outcomes, very low rates of adverse events and no structural valve
deterioration or thrombosis were reported in patients with the Regent
valves. Embolism occurred in only 4.8% and valve-related death in only
0.9% of patients. All valve sizes, ranging from 1.0
±
0.2 cm
2
/m
2
in the 19 mm
0.2 cm
2
/m
2
in the 29 mm valve, afforded excellent hemody-
namics. The authors
51
noted that prosthesis-patient mismatch is usually
obviated if the effective orifi ce area exceeds 0.85 cm
2
/m
2
. Similar favorable
results emerged from a large 25 year retrospective study of 4480 implants
of the three St. Jude Medical valve series used for single aortic or mitral
valve replacement.
52
valve to 2.4
±
4.3.5 On-X prosthetic heart valve
In 1996 Dr Jack Bokros and a team of engineers developed and designed
the On-X prosthesis, motivated by a desire to improve existing bileafl et
valves. Bokros was the originator of the pyrolytic carbon used in the fi rst
generation of cardiac valve prostheses. In the mid-1990s he developed a
new form of pure pyrolytic material free of silicon carbide that was stronger
and had a smoother surface than the original material. The On-X valve
constructed from this pure pyrolytic carbon features an extended fl are to
minimize turbulence and prevent pannus (fi brous ingrowth) progression.
The hinge is confi gured to optimize washing effect and prevent clot forma-
tion. Coating the housing and leafl ets with the new pyrolytic carbon imparts
Search WWH ::
Custom Search