ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

A TAWSS [Pa]
B OSI [Pa]
C
0 0.25 0.5
Figure 4. Comparison of the near-wall fluid dynamic variables in case of the culotte technique performed
with the Tryton stent (top) and with two Multilink stents (bottom). Contour maps of: A) time-averaged
WSS (regions with low WSS are red colored), B) OSI, C) RRT.
distribution of the eluted drug disturbing the correct healing process of the artery.
In Fig. 4 the main fluid dynamic results are shown. In particular, the following nearwall
quantities are represented: TAWSS (time-averaged WSS), OSI (oscillatory shear
index) and RRT (relative residence time). Low TAWSS, high OSI and high RRT are
recognized as critical for the process of atherogenesis and in-stent restenosis. The case
of the culotte technique performed with the Tryton stent show a smaller area with
TAWSS lower than 0.1 Pa in comparison to standard stents (28.7% versus 35.5%).
Moreover the dedicated model has a lower area with high OSI. RRT contour maps
confirm TAWSS and OSI results, with lower values in the case of the dedicated stent. In
fact, RRT is a combination of the two previously mentioned quantities but it has a more
tangible connection to the biological mechanisms underlying atherosclerosis [10].
Concerning stenting procedures involving two or more devices, another important
aspect is the difficulty of stent positioning inside the bifurcation. In this work, the ease
of access to MB for the second device implanted during the culotte technique is
investigated. Figure 5 illustrates the geometrical configuration at the MB access of the
Multilink and Tryton stents. The green area corresponds to the optimal crossing region
to obtain a good access to MB, few struts at the SB ostium and low stent deformations.
The dedicated device provides a wider area (63.4%) available for an optimal re-crossing
if compared to the Multilink stent (10.9%). Furthermore, a sub-optimal procedure
performed with Tryton rotated of 30° or 60° (worst scenario) still enhances the
performances of the standard device examined, maintaining the crossing area at 45.4%
and 37.6%, respectively.
5. CONCLUSIONS
0 0.25 0.5
CULOTTE WITH TRYTON AND MULTILINK VISION
CULOTTE WITH TWO MULTILINK VISION
RRT [Pa -1 ]
0 7.5 15
Structural and fluid dynamic simulations of the culotte technique were performed in
order to compare the behavior of a dedicated device, the Tryton stent, with a standard
one. Results show that Tryton stent reduces the metal-to-artery ratio and the
deformation of stent struts, improving also the fluid dynamics with a smaller area
subjected to low and oscillating WSS. Moreover, the dedicated stent facilitates the