Experimental arterial stent placement. Comparison of a new Nitinol stent and Wallstent.
OBJECTIVE
To compare technical aspects and neointima formation of a new Nitinol stent and a Wallstent.


METHODS
A Nitinol sten and a Wallstent were placed into the iliac arteries of 14 sheep (total of 28 stents) and followed angiographically. Seven sheep were killed after 1 month and 7 after 4.5 months. Examination of histologic specimen by light microscopy was performed to determine neointimal and medial thickness inside the stents. Measurements were analyzed statistically.


RESULTS
Neointima was thicker in Nitinol stents (N) than in Wallstents (W) (P < 0.004), both adjacent to (W = 0.265 mm, N = 0.596 mm) and between the stent wires (W = 0.177 mm, N = 0.361 mm). Because of poor radiopacity and the Crochê releasing technique, delivery was more difficult with Nitinol stents. High-grade stenosis was found in two Nitinol stents at 1 and 4.5 months of follow-up, respectively. One Wallstent was insufficiently incorporated into the vessel wall.


CONCLUSIONS
The observed difference in neointima formation that may be caused by differences in design, mechanical properties or the metal alloy of the stents probably is too insignificant to be relevant to patency of large arteries. However, it may be relevant in small vessels such as coronary arteries.
Schürmann
K
K
Department of Diagnostic Radiology, University of Technology, Aachen, Germany.
Vorwerk
D
D
Kulisch
A
A
Stroehmer-Kulisch
E
E
Biesterfeld
S
S
Stopinski
T
T
Günther
R W
RW
D000497:Alloys; D000818:Animals; D001157:Arterial Occlusive Diseases / Q000000981:diagnostic imaging / Q000473:pathology; D001696:Biomechanical Phenomena; D003035:Cobalt; D003251:Constriction, Pathologic / Q000000981:diagnostic imaging / Q000473:pathology; D004867:Equipment Design; D005500:Follow-Up Studies; D007083:Iliac Artery / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D007501:Iron; D011859:Radiography; D012756:Sheep; D015607:Stents; D013499:Surface Properties; D017539:Tunica Intima / Q000000981:diagnostic imaging / Q000473:pathology; D017540:Tunica Media / Q000000981:diagnostic imaging / Q000473:pathology; D014654:Vascular Patency
D000497:Alloys; C013616:nitinol; D003035:Cobalt; D007501:Iron