Page 235 - IJB-9-2

International Journal of Bioprinting Coronary and peripheral artery disease. State of the art.

Table 2. Differential properties and features of peripheral and coronary blood vessels influencing the patency of PAD and CAD
stenting
Differential characteristic Coronary blood vessels Peripheral blood vessels
Blood flow Excellent autoregulation (60–200 mm Hg) to Moderate autoregulation (50–70 mmHg). Stenosis could
maintain normal blood flow under aortic pres- reduce distal pressures below the autoregulatory range causing
[24]
sure changes . maximally dilated vessels and further pressure reductions [25]
Blood oxygenation Flow tightly coupled to oxygen demand due to Moderate pressure autoregulation could lead to tissue hypoxia.
high basal oxygen consumption by heart .
[24]
Extent of the stenosed lesion Smaller, localized lesions. Much longer lesions, usually located between muscle and
bone.

that affects peripheral blood vessels, such as femoral, factor to consider when designing and implanting a stent
iliac or popliteal arteries, among others . In fact, the is the extent of the stenosed lesion: in CAD, normally the
[21]
endovascular treatment of PAD still yields unsatisfactory size of the stenosed area is smaller and more localized
patency rates or no significant differences between (always with exceptions), while in PAD, the lesions can be
[22]
stenting and percutaneous transluminal angioplasty (PTA) much longer and usually located between muscle and bone
in the lower extremities . Among subjects with diabetes, tissue. The lesion size and its location imply that the stent
[23]
the risk of PAD is often severe and associated with will be subjected to higher level of movements and stresses
extensive arterial calcification, thus leading to a particular (e.g., displacement, fracture, crushing). Therefore, more
type of lesion that could complicate the stenting procedure. flexible VS are preferred for PAD, while the VS is allowed
Definitely, PAD and CAD respond differently toward the to be a little stiffer for CAD because it will not be subjected
same pathology and intervention, due to differential to so much movements.
features and characteristics summarized in Table 2. The
differential anatomy of coronary and peripheral arteries 2. Desirable stent features
(size, bifurcations, elasticity, and curvature) influences the In general, the perfect VS has the ability to be crimped in
shear stress and blood turbulences, indicating the need to agreement with the implantation methodology (balloon
adjust the VS to the idiosyncrasy of each vessel. The blood or self-expansion), and has good expandability ratio with
flow and blood pressure and perfusion is better regulated enough radial strength and minimal recoil. VS must also be
in the heart due to excellent autoregulation mechanisms of flexible and fully biocompatible, as well as able to prevent
these vessels, thus guaranteeing optimal blood flow ; on or avoid thrombosis and restenosis after implantation .
[24]
[26]
the other hand, other organs such as skeletal muscle and These desirable properties and features are intimately
splanchnic circulations show moderate autoregulation . related to the stent raw materials, their combinations,
[25]
If blood pressure drops to below the autoregulatory range and the intrinsic features of each of them as well as the
due to pathologies such as stenosis, the distal vessels will manufacturing process and post-processes. Nevertheless,
be maximally dilated in an attempt to guarantee proper the geometry and design of the VS are likewise important to
blood flow, thus causing further pressure reductions. control the final properties of the medical device, including
When stenting peripheral blood vessels, the moderated the mechanical properties . Under these circumstances,
[27]
autoregulation of blood pressure and flow could hinder the study of the geometry and dimensions of VS is a field
the function of the vessel in maintaining the open of study on its own due to the myriad of possibilities. In
lumen. Because of this, stents with better radial force are this sense, computational studies have proven themselves
desirable for PAD. Another factor to bear in mind is blood as useful tools to analyze and predict the influence of stent
oxygenation of the tissues in the distal region of the stenosed design on the final performance.
vessel. When it comes to the heart, the flow is tightly
coupled to oxygen demand (when cardiac O consumption Good expandability is the property of a material to
2
increases, there is an increase in coronary blood flow) , expand (active expansion or self-expandability) or to be
[24]
indicating that it is more easily compensated in CAD. In expanded (passive expansion). VS implanted with a balloon
the case of PAD, the moderated pressure autoregulation are passively expanded by the inflation of the balloon.
of the peripheral tissues could lead to oxygen-starvation Therefore, the materials used for the manufacturing of
of the distal tissues as well as inflammation, hypoxia, balloon-expandable stents need to be more plastic than
edema, ulceration, and, ultimately, amputation in the long elastic. On the contrary, self-expandability of VS refers to
term. The lower blood oxygenation in PAD worsens the the ability of the medical device to expand without the use
prognosis of the treatments, including stenting. Another of an external force and to retain the final shape. This can

Volume 9 Issue 2 (2023) 227 https://doi.org/10.18063/ijb.v9i2.664