Supplemental Appendix
Details of bifurcation techniques
Kissing balloon inflation. The main vessel and side-branch were wired and a 3.0x18
mm BVS was deployed in the main vessel, covering the side-branch. A third
guidewire was maneuvered through the struts covering the side-branch, ensuring
that the wire entered the side-branch through the most distal cell possible in order
to minimize distortion of the main vessel stent struts after kissing balloon inflation
and to create a small ‘flap’ of the main vessel scaffold to cover the proximal aspect of
the side-branch ostium.(10) A kissing-balloon inflation was then performed with a
2.5x20 mm balloon in the side-branch and a 3.0x20 mm balloon, both inflated to 8
atmospheres.
It is now common practice to perform the proximal optimization technique (POT) in
order to facilitate wire reentry into the jailed side-branch and to optimize apposition of
the proximal segment of the main vessel stent, since the stent diameter was chosen for the
diameter of the distal segment of the main vessel. The optimized apposition minimizes
the risk of the wire utilized to re-enter the jailed side-branch from entering the proximal
segment external to the proximal segment of the BVS. However, our simple phantom had
the same 3.0 mm diameter proximal as well as distal to the bifurcation. Therefore optimal
apposition was achieved with the initial BVS deployment. Despite the absence of this
step, wire reentry and balloon crossing into the jailed side-branch were not problematic.
In a real life situation, this step would be desirable.
Modified T-stenting. This next step was intended to deploy a side-branch scaffold in
a ‘provisional’ manner, that is, after deployment of the main vessel scaffold, in a T-
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stenting technique. As in the kissing balloon procedure both vessels were wired, the
main vessel was covered with a 3.0x18 mm BVS, and the side-branch was rewired
and dilated with a 2.5x20 mm balloon at 12 atmospheres. A 2.5x18 mm BVS was
then advanced through the open struts into the side branch. A 3.0x20 mm balloon
was positioned in the main vessel covering the side-branch. The proximal BVS
balloon marker was then lined up with the carina and the BVS was deployed at 14
atmospheres. The balloon was then withdrawn, a 2.5x20 balloon was positioned
partly in the main vessel, and a kissing balloon inflation was performed with both
balloons inflated to 8 atmospheres. A second procedure was performed utilizing
identical technique, except that the final kissing balloon inflation was carried out
with both balloons inflated to 10 atmospheres.
Crush techniques. The double crush or step crush technique was performed by first
wiring both the main vessel and the side-branch. After wiring, a 2.5x28 mm BVS was
positioned in the side-branch, with 4 struts protruding into the main vessel. A
3.0x20 mm balloon was positioned in the main vessel, covering entirely the
protruding BVS. The BVS was deployed at 14 atmospheres, the balloon and sidebranch wire were removed, and the main vessel balloon was inflated also to 14
atmospheres, thus crushing the BVS in the main vessel. The crushed side-branch
BVS was rewired through the crushed struts at a mid-ostial entry point, avoiding
distal strut reentry that could result in deformation of the crushed stent and lack of
BVS coverage in the distal aspect of the ostium, a previously inflated 2.5x20 mm
balloon was advanced through the struts partly into the side-branch. A 3.0x20 mm
balloon was positioned in the main vessel, fully covering the side-branch. The side-
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branch balloon was then inflated to 16 atmospheres. The side-branch balloon and
guidewire were withdrawn and the main-vessel balloon was inflated to 14
atmospheres. The balloon was then removed and a 3.0x18 mm BVS was deployed in
the main vessel, covering the scaffolded side-branch, which was then rewired. A
final kissing balloon inflation was then performed with a 3.0x20 mm balloon in the
main vessel and a 2.5x20 mm balloon in the side-branch, with each inflated
individually in a sequential fashion, and then with both balloons inflated to 8
atmospheres. This procedure was repeated in a similar manner a second time. A
classic mini-crush technique was also performed, with a 2.5x28 mm BVS deployed
in the side-branch at 14 atm. with 2 struts protruding into the main vessel crushed
by 3.0x18 mm BVS deployed in the main vessel at 16 atm. The side-branch was
rewired and a 2.5x20 mm Mini Trek was advanced through the struts. The
positioning of the side-branch balloon caused a distal movement of the side-branch
BVS away from the bifurcation. The balloon was positioned partly outside of the BVS
distally, inflated gently and pulled back, bringing the side-branch BVS back into
position. The balloon was pulled back further, partly into the main vessel, and
inflated to 14 atm. A 3.0x20 mm NC Trek was then advanced into the main vessel
and a gentle FKB was performed, with both balloons inflated to 8 atm.
Culotte technique. After wiring the side-branch, a 3.0x28 mm BVS was deployed at
14 atmospheres, mostly in the side-branch and approximately 6-8 mm in the
proximal main vessel, following which the distal main vessel was wired with a
second wire. A 3.0x20 balloon was advanced through the struts, partly into the
distal main vessel, and inflated to 14 atmospheres. A 3.0x18 mm BVS was then
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maneuvered across the dilated cell into the distal main vessel, with the proximal
portion completely covering the proximal main vessel segment of the side-branch
scaffold, and following removal of the side-branch wire, was deployed at 14
atmospheres. The side-branch was then rewired, and the side-branch and main
vessel were sequentially post-dilated to 8 atmospheres.
Micro CT Methods
Five pairs of overlapped pairs of Absorb BVS constrained in PVA mock vessels were
scanned using a high-resolution computed tomography system (GE Preclinical
eXplore Locus RS Micro CT). Images were acquired at 80 kV and 425 µA, with the
specimens in contrast solution to enhance the segmentation of the scaffolds from
the PVA mock vessels. Each scan produced 720 cross-sectional slices with 20 micron
isotropic voxel resolution. These two-dimensional images were processed using
GE’s proprietary algorithms to create three-dimensional (3D) reconstructions of the
scanned specimens.
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