Biomedical Engineering Reference
In-Depth Information
The fi rst implant was implanted too low, showing signifi cant aortic regur-
gitation. A second implant was implanted successfully, with no documented
post-implantation paravalvular or valvular regurgitation. The patient
returned home on day 7 after an uneventful hospital stay. Control echocar-
diography showed 15 mmHg of transvalvular gradient and no valvular
regurgitation, centro- or paravalvular.
In February 2005, a 68-year-old female with severe aortic calcifi ed steno-
sis received a revalving procedure through a right inferior limb artery cut-
down. The patient was able to walk to her postoperative day 2 control
echocardiogram, which showed low transvalvular gradient and no valvular
regurgitation, centro- or paravalvular.
The patient returned home after an uneventful hospital stay.
Since these early procedures, more than 4000 successful implantations
were achieved successfully around the world, using different access points
(transapical, subclavian and femoral).
The self-expandable approach used by CoreValve differs from the
Edwards SAPIEN Life Sciences system in different ways. Indeed, the self-
expanding aortic valve prosthesis was initially designed for retrograde
implantation via the peripheral arteries. Whereas animal studies have
shown that the balloon-expandable prosthesis requires exact device posi-
tioning to avoid device embolization,
12
the profi le and properties of nitinol
could improve the easiness of deployment and the stability of the
implant.
24
Even though nitinol devices could be susceptible to fracture with time,
the self-expandable technology is used commonly in thoracic aortic stent
grafting and has given satisfactory results.
25
One additional advantage of
self-expandable technology is the potential for continued expansion over
time, which may in turn reduce paravalvular leaks after implantation.
24
Emerging advances in percutaneous technologies include reduced delivery
catheter diameter and alternative approaches (retrograde subclavian or
transapical approaches), which may represent an alternative to iliofemoral
retrograde approach and may reduce the risk of implantation failure in
patients with severe peripheral vascular disease.
26,27
5.7
Future trends
The retrograde approach proposed with the actual catheter size tracking
over the wire may encounter some diffi culties in small and diseased arter-
ies, but avoids further damage to the mitral anterior leafl et. The self-
expanding multisegment frame prosthesis is a concept that has a number
of advantages: avoiding ballon damage to the pericardial leafl ets at the
time of implantation, providing improved radial force for better anchor-
age on the annulus, preventing periprosthesis leak and migration, and per-
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