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

four sample patient data, outcomes based on previous papers have been obtained. First
of all, it can be deduced that transients within a cardiac cycle is important to consider
for evaluating of stent efficiency, since depending on the geometry of the aneurysm, the
oscillations and spatial distribution of blood velocity is away from unity. It can be seen
that, stent application does have implied a mean velocity reduction about 40% but the
maximum velocities within the sac volume has not significantly decreased; for one
patient, it is observed to increase.
Unstented Stented
Figure 3 – Change of Flow field with Stent Application (Patient 4)
It is a chance that we have the patient follow up data for all the patients, which other
than data available in the literature; provide the real case outcomes and are given in
Table 1. It is not good for aneurysm treatment to have a very high decrease in mean
velocity without having enough reduction over maximum velocity; otherwise there is a
risk of rupture (as in Patient 4), if the aneurysm wall is not exposed to synovial fluid (as
is the case for Patient 2). It is also seen that, maximum velocity reduction might be an
important factor for immediate treatment of aneurysms, since our outcomes imply that
maximum velocity reduction is directly proportional to immediate clotting within the
sac (Patient 4 does clot, where as Patient 1, 2 and 3 does not. Patient 1 and 3 turns OK
in the long run, but Patient 2 fails to respond to treatment). The decrease in transient
behavior of flow within the sac is seen to be an efficient thing for treatment (Patient 1),
but treatment is generally observed to increase oscillatory behavior within the aneurysm
sac (Patient 2-4). That is also dependent to the aneurysm neck position – Patient 1 is a
pure side wall aneurysm, whereas Patients 2-4 have much wider necks and rather look
like a balloon through which fluid flow.
5. CONCLUSION AND FURTHER STUDIES
CFD models of real stent application cases were generated, and parameters related to
aneurysm flow are calculated. The results were compared to real follow-up data of the
patients, and meaningful results were obtained that could help understanding stent
efficiency. Parameters developed can be further analyzed on many examples so that
statistically meaningful outcomes can be developed. This study exhibit the limitation of
assuming rigid arterial wall, sac wall and stent assumption, which might lead to change
in the volume of the sac during a cardiac cycle and alter the flow pattern. It is also
known by the authors that this preliminary study is not promising a net statistical
outcome with respect to patient count considered, but is rather proposing a challenge to
the way of thinking for engineers interested in biomechanics of aneurysms and a