Developments in cardiovascular valve technology - Biomaterials and Devices for the Circulatory System - page 101

linearized rate of valve failure was 0.75% per patient-year. Actuarial
freedom from valve failure was 100% for the Shiley valves, 86% for the
'hospital made' valves, and 90% overall. Ionescu 68 also reported hemody-
namic performance of pericardial valves in 29 standard and 12 low profi le
mitral xenografts impanted between 1971 and 1976. Mean diastolic pressure
gradient at rest was 6.4 ± 0.5 vs. 4.5 ± 0.4 mmHg at rest and 15.3 ± 0.9 vs.

12.8 0.8 during exercise in standard vs. low profi le xenografts; these results

are considered moderately abnormal. Ionescu et al. 62 concluded that peri-
cardial mitral valve replacement can be performed without anticoagulants
at minimal risk, thereby avoiding hemorrhagic events, and that the valves
had excellent durability for

±

10 years.
With more extensive experience with the standard Ionescu pericardial
prosthesis, more recent reports indicate actuarial freedom from primary
valve failure of 95% at 6 years and 90% at 11 years. In the authors' experi-
ence with explanted valves at surgery, cuspal tearing, calcifi cation and pros-
thetic valve endocarditis (Fig. 4.12) accounted for the late failure of this
valve. 69

≥

4.4.6 Carpentier-Edwards pericardial bioprosthesis

The Carpentier-Edwards bioprosthesis was developed after the Ionescu
pericardial valve had entered clinical use. It underwent several modifi ca-
tions in its design, preservation, and fi xation that improved its function and
durability. Currently manufactured by Edwards Lifesciences (Irvine, CA),
the Carpentier-Edwards valve (Fig. 4.13) is constructed with three opti-
mally matched bovine pericardial leafl ets fi xed with 0.625% glutaraldehyde,
treated with anticalcifi cation solution, and mounted in a fl exible and resil-
ient metallic stent. The stent is designed to reduce stress on the free margins
and bases of the cusps. The Perimount valve (Fig. 4.14), a new generation
Carpentier-Edwards bioprosthesis, has a sewing ring confi gured for supra-
annular, intra-annular, aortic, or mitral positions. The Perimount Magna
Model is designed with a compact sewing ring which increases the valve
orifi ce area over that of the standard model of the same annulus diameter.
Clinical and hemodynamic reports with the Perimount Magna valve are
favorable, and it seems especially well suited for small aortic roots, mitigat-
ing patient-prosthesis mismatch.
Within the last decade several reports 70-75 have described the long-term
clinical and hemodynamic performance of the Carpentier-Edwards bio-
prosthesis for mitral or aortic valve replacement. These reports, many cov-
ering

￿ ￿ ￿ ￿ ￿

15 years of follow-up, document excellent survival of valve recipients
and very limited valve-related complications. The Carpenter-Edwards
valve is almost unequivocally considered the bioprosthesis of choice
for the ever-expanding elderly population. The risk of structural valve

≥