Self-expanding nitinol renal artery stents: comparison of safety and efficacy of bare versus Polyzene-F nanocoated stents in a porcine model.
OBJECTIVE
To investigate the safety and efficacy of a Polyzene-F nanocoat on new low-profile self-expandable nitinol stents in minipig renal arteries.


METHODS
Ten bare nitinol stents (BNS) and 10 stents coated with a 50 nm-thin Polyzene-F coating were randomly implanted into renal arteries of 10 minipigs (4- and 12-week follow-up, 5 animals/group). Thrombogenicity, on-stent surface endothelialization, vessel wall injury, late in-stent stenosis, and peristrut vessel wall inflammation were determined by quantitative angiography and postmortem histomorphometry.


RESULTS
In 6 of 10 BNS, >50% stenosis was found, but no stenosis was found in stents with a nanothin Polyzene-F coating. Histomorphometry showed a statistically significant (p < 0.05) different average maximum luminal loss of 55.16% ± 8.43% at 12 weeks in BNS versus 39.77% ± 7.41% in stents with a nanothin Polyzene-F coating. Stents with a nanothin Polyzene-F coating had a significantly (p < 0.05) lower inflammation score after 12 weeks, 1.31 ± 1.17 versus 2.17 ± 0.85 in BNS. The results for vessel wall injury (0.6 ± 0.58 for Polyzene-F-coated stents; 0.72 ± 0.98 for BNS) and re-endothelialization, (1.16 ± 0.43 and 1.23 ± 0.54, respectively) were not statistically significant at 12-week follow-up. No thrombus deposition was observed on the stents at either follow-up time point.


CONCLUSIONS
Nitinol stents with a nanothin Polyzene-F coating successfully decreased in-stent stenosis and vessel wall inflammation compared with BNS. Endothelialization and vessel wall injury were found to be equal. These studies warrant long-term pig studies (≥120 days) because 12 weeks may not be sufficient time for complete healing; thereafter, human studies may be warranted.
Clinics for Diagnostic and Interventional Radiology, Klinikum Stuttgart, Kriegsbergstr. 60, 70174, Stuttgart, Germany.
P
P
Kurz
U
U
Stampfl
P
P
Christoph
C
C
Henn
S
S
Satzl
B
B
Radeleff
I
I
Berger
G M
GM
Richter
D000497:Alloys; D000792:Angiography; D000818:Animals; D020099:Coated Materials, Biocompatible; D006083:Graft Occlusion, Vascular / Q000517:prevention & control*; D036103:Nanotechnology; D009943:Organophosphorus Compounds; D011108:Polymers; D015641:Radiography, Interventional; D011897:Random Allocation; D012077:Renal Artery; D018709:Statistics, Nonparametric; D015607:Stents; D013552:Swine; D013556:Swine, Miniature
D000497:Alloys; D020099:Coated Materials, Biocompatible; D009943:Organophosphorus Compounds; D011108:Polymers; C108974:poly(phosphazene); C013616:nitinol