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Coronary Stents
THE JOURNAL OF MEDICINE FOR THE WORLDWIDE MED COMMUNITY
Коронарные стенты
The most frequently used polymer
in the current generation
of BDS is PLLA and poly-D,Llactide
(PDLLA), both utilized
as resorbable sutures, softtissue
implants, or orthopedic
implant. The PLLA and PDLLA
are metabolized via the Krebs
cycle over a period of approximaterly
12 to 18 months and
converted to carbon-dioxide
and water. At present, no BDS
has either the C.E. mark or
U.S. FDA approval.
The BVS (Bioabsorbable
Vascular Scaffold) EES (Abbott
Vascular) is a manufactured
from PLLA polymer and is
coated with a formulation
of everolimus in a PDLLA
polymer matrix which contains
and controls the release of
everolimus from the stent. The
drug-polymer coating is applied
to the entire stent surface
with a standard concentration
of approximately 8.2μg/mm
stent length and is designed to
release approximately 80% of
the total dose within 30 days
of stent placement; polymeric
strut absorption will take approximately
two years. Following
encouraging pre-clinical
studies, both safety and feasibility
of the first-generation
BVS implant were assessed
in 30 low-risk patients with
de novo coronary lesions who
were enrolled in the propective,
open-label, multicenter
FIM ABSORB study [45]. The
study demonstrated clinical
safety of the BVS as there was
only 1 ischemia-driven MACE
at 6 months, whereas no
MACE events were reported
in the following 30 months. Of
note, no stent thrombosis has
been observed over 3 years
follow-up [46]. At two-year
follow-up angiography, the instent
late loss of 0.48mm and
the diameter stenosis of 27%
did not significantly differ from
the findings at six months. In
addition, there is evidence of
restoration of vasomotor function
in the stented segment
[45].
Beside bioabsorbable polymer-coated
DES there are
bioabsorbable polymer-free
stents. The balloon-expandable
AMS-1 BDS is composed of
93% magnesium and 7% rare
earth metals. The stent has a
high mechanical strenght, and
has properties comparable to
stainless steel stents, such
as low elastic recoil (