Comparison of Pura-Vario and Palmaz-Schatz stents following implantation using normal and high pressure in pigs: immediate and late results assessed by 3-dimensional IVUS.
BACKGROUND
The Pura-Vario stent features 2 newly designed "bridging segments" for enhanced longitudinal flexibility, in order to allow easier and safer stent implantation.


METHODS
The aim of the present experimental investigation was to analyze the expansion characteristics of the Pura-Vario stent (PV), and to compare it with the Palmaz-Schatz stent (PS). Furthermore, stent implantation using "high pressure" (18 atm) (HP) was compared with "normal pressure" (12 atm) (NP). Stents (n = 16) were implanted into the left anterior descending artery (LAD) and the circumflex artery (CX) of 8 pigs. Stent area, lumen area and stent asymmetry were measured by means of three-dimensional intravascular ultrasound (3D-IVUS): (1) immediately after implantation, and (2) at 14-days follow-up.


RESULTS
Stent expansion was found not to be uniform: the "bridging segments" were significantly larger than the "diamond segments" in either stent model at day 0; this difference, however, disappeared at 14-days follow-up. Despite higher flexibility of the Pura-Vario stent, no difference in stent expansion was found between both stent models, neither immediately after implantation (mean lumen area: 9.75 +/- 0.28 mm2 (PV) vs. 9.82 +/- 0.34 mm2 (PS)), nor at 14-days follow-up (7.44 +/- 0.16 mm2 (PV) vs. 7.45 +/- 0.22 mm2 (PS)). Pura-Vario stents, however, were less asymmetric in the cross-sectional view. Implantation using "high pressure" resulted in larger and less asymmetric stent expansion only at day 0 (lumen area: 9.54 +/- 0.39 mm2 (HP) vs. 8.77 +/- 0.33 mm2 (NP) (p < 0.05)); this difference, however, disappeared after 14 days due to higher stent recoil in the "high pressure" group.


CONCLUSIONS
Despite higher flexibility of the Pura-Vario stent, expansion characteristics of both stent models were comparable. "High pressure" implantation compared favorably with "normal pressure" implantation only at day 0, whereas no difference could be found between both techniques at 14-days follow-up.
von Degenfeld
G
G
Med. Klinik I, Klinikum Grosshadern, München.
Heinrich
D
D
Giehrl
W
W
Boekstegers
P
P
D000818:Animals; D003331:Coronary Vessels; D003627:Data Interpretation, Statistical; D019160:Endosonography; D011312:Pressure; D019919:Prosthesis Implantation / Q000379:methods*; D011897:Random Allocation; D015607:Stents; D013552:Swine