Principles of Clinical and Engineering Integration in Hemocompatibility - Biomaterials Science: An Integrated Clinical and Engineering Approach - page 21

artery of a preterm baby allowed the reperfusion of the left lung. The reper-
fusion persisted throughout the 4-month follow-up period during the degra-
dation process of the stent until it was completed. The degradation process
was clinically well tolerated by the baby [49, 60].
The bioabsorbable magnesium stent was also evaluated in the human
coronary arteries in the PROGRESS-AMS (Clinical Performance and
Angiographic Results of Coronary Stent) study [57]. This study was a pro-
spective, multi-center, consecutive, non-randomized study of 63 patients
with coronary artery disease that addressed the safety and feasibility of this
stent deployment in human coronary arteries. The primary endpoint of this
study included major adverse cardiac events (MACE) at 4 months. These
were defined as cardiac death, nonfatal myocardial infarction, and ischemia-
driven target lesion revascularization. In a sub-study of PROGRESS-AMS,
Ghimire et al. assessed the endothelium independent coronary smooth mus-
cle vasomotor function 4 months after implantation of the stent in 5 patients.
This group was compared with a control group of permanent metal stents
(n = 10) undergoing follow-up angiography and who were free from angio-
graphic restenosis [59].
The bioabsorbable stent was shown to be safe overall, with a high proce-
dural success rate of 99.4%. Moreover, the stent showed its ability to degrade
well. No adverse events or distal embolization were observed. In addition, the
targeted vessel regained its vasoreactivity properties. A major disadvantage,
however, was its association with higher than expected restenosis rates. These
results were associated with early recoil and neointima formation [57, 59, 60].
These materials show that ultimately their advantages as well as disadvan-
tages must be correlated with clinical trials and long-term follow-ups. That
is, ultimately, their widespread use will be dependent on clinical end-points
that include morbidity and mortality parameters being well stratified [2].
Drug-Eluting Balloons (DEB)
While a complete discussion of the topic of drug-eluting balloons is beyond
the scope of this chapter, its relevance to hemocompatibility will be dis-
cussed. Their salient advantage over DES is their ability to not leave behind
an implant. It should be noted, however, DEB cannot overcome the important
mechanical limitation of acute recoil, which can be seen with postballoon
angioplasty [72].
Several architectures can exist for DEB, yet only one will be discussed here.
The DEB may consist of several components, which can include a balloon,
elongated members, and reinforcing strands. Reinforcing strands between the
inside surface of the balloon and the outside of the elongating member can
enhance the balloon when inflated as it is subjected to high pressures. When
the balloon is not collapsed, a lumen can exist between the inner surface of the