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

small improvements in PAD treatment could bring about 1.1. Types of vascular stents and their features
significant differences not only for the patients, but also for VS have been in use since 1977 [10] . From that moment
the entire health care system. onward, different aspects concerning VS, such as

Angioplasty, also known as percutaneous transluminal the type of materials used and the implantation and
coronary angioplasty (PTCA) or percutaneous production technology, have significantly evolved.
transluminal angioplasty in peripheral circulation, is Any innovation in VS field comes with new challenges
an interventional procedure to open narrowed vessels. arise, either in the manufacturing process or in the final
Balloon angioplasty involves opening the stenosed vessel performance of the medical device. The joint effort of the
by inflating a catheter-balloon in the stenosed area. Once scientific community in the search for the full-patency
the catheter reaches the desired zone, the attached balloon VS has given rise to the development of a wide variety
inflates to flatten the atheroma plaque against the artery of cardiovascular stents, which are currently available in
walls. Subsequently, the device (balloon and catheter) the market (Table 1). Figure 2A represents different types
is withdrawn and the vascular vessel remains opened. of VS depending on their permanence in the human
Balloon angioplasty provides short-term benefits with body, the implantation methodology and the therapeutic
some improvements in patency. activity together with their relative presence in the
current market (Figure 2B).
In stent procedure, on the other hand, VS is placed in
Permanent stents or non-resorbable stents are made of
the treated area after the flattening of atheroma. VS are materials that do not suffer degradation under physiological
cylindrical medical devices acting as endoprothesis. VS conditions. The first VS were bare metal stents (BMS), which
implantation aims to support the walls of a blood vessel were made of stainless steel and nickel-titanium alloy (first-
during a certain period of time and prevent restenosis. Once generation stents). It is possible to find cobalt, chromium,
the VS is implanted in the desired position, its final scope is platinum/iridium and platinum/chromium, or tantalum
to exert permanent pressure against the vessel walls, acting BMS . One of the main inconveniences of BMS are the
[11]
as a scaffold to keep the artery or vein open until the risk of long-term side effects: although they help to maintain the
full closure finishes. VS can also be used as flow diversion angioplasty result and they possess excellent mechanical
devices to treat aneurysm. In this procedure, the stent properties, the remaining of the medical device within the
redirects the blood flow and eliminates the pressure on the vascular vessel could lead to vascular injury, inflammation,
aneurysm, reducing the rupture risk.
thrombosis, and other cardiovascular complications, such
Disregarding the type of intervention, the ultimate as in-stent restenosis in the long term [8,12] . According to
objective against atherosclerosis complications is to Uhlemann et al., BMS have approximately a 30% chance of
guarantee blood circulation in the long term after the vessel restenosis within 6 months . Moreover, their permanent
[13]
opening, also referred to as patency. The patency is the state presence may interfere with future cardiac interventions.
or quality of being open, unblocked, or unobstructed. Even The corrosion of metallic VS might accelerate or trigger
as it seems simple, full patency after angioplasty is still a atherosclerosis as well as release some toxic ions causing
challenge. Although VS is an innovation in cardiology long-term inflammatory responses .
[14]
that has helped saving millions of lives worldwide, they
still have some drawbacks and weak points in peripheral BMS can be coated with different substances, aiming
vascular disease that require attention. to modify their superficial properties and improve their
mechanical, biological, and therapeutic performance.
The present review focuses on the most recent studies Stent surface coating has been used to improve VS
using three-dimensional (3D) printing techniques to biocompatibility and mitigate toxicity. Bearing in mind
produce VS, both by itself and in combination with that the internal part of the stent is in intimate contact
other techniques. Due to the complexity of both disease with blood flow, they must be fully biocompatible and able
and treatments/medical devices used, the first part of the to avoid platelet, protein, and other molecules adhesion
review is devoted to the most common types of VS, their while maximizing the adherence of specific cells such as
characteristics, and production techniques. The paper also endothelial cells. Coating process enables to control and
focuses on the use of 3D printing (3DP) by reviewing the reduce corrosion (oxidation) and the release of undesirable
most recent studies that have approached this technique elements or chemicals [15,16] . The category “coated stents”
for the manufacturing of VS. The ultimate aim of this usually overlaps with “drug-eluting stents” (DES), since
review is to offer a rational overview of the strengths and organic coatings (mainly polymers such as poly(ethylene),
weaknesses of 3DP in the development of these medical polyurethane, polylactides…) can act as drug reservoirs
devices, identifying research gaps, possible market niches, with controlled drug release properties.
and feasible future directions.

Volume 9 Issue 2 (2023) 221 https://doi.org/10.18063/ijb.v9i2.664