Self-expandable and highly flexible nitinol stent: immediate and long-term results in dogs.
We sought to investigate the acute and long-term patency rates and the histologic response of coronary arteries to a self-expandable nitinol coil stent. Twenty-two stents were implanted. Angiographic patency was demonstrated acutely in all but one dog, in which the stent was released in a small branch (1 mm); mismatch in stent-to-artery diameters resulted in vessel closure. Two dogs died from anesthesia overdose and two from bleeding within 24 hours. All dogs were treated with aspirin (80 mg/day) and warfarin (2.5 mg/day) for up to 1 month. Sixteen dogs were monitored for 1 to 2 weeks, 1 month, 3 months, 6 months, and 1 year and underwent subsequent angiography and histopathologic examination. Angiographic artery dimensions measured immediately after stent implantation (2.72 +/- 0.4 mm) did not differ from those noted at follow-up (2.68 +/- 0.44 mm, p not significant). Histologic examination showed outward stent pressure compressing the internal elastic membrane and media in most cases. Intimal hyperplasia started at 2 weeks and was most apparent at 3 and 6 months. Mean intimal thickness was 30.7 +/- 10.9 mu, 141.8 +/- 105.4 mu, 227.1 +/- 104.1 mu, 211.8 +/- 99.1 mu, and 170.1 +/- 42.7 mu at 1 to 2 weeks and 1, 3, 6 and 12 months, respectively. Therefore the nitinol self-expandable stent provokes a moderate cellular proliferative response that reaches its maximum in 3 to 6 months without further progression.
Grenadier
E
E
Division of Cardiology, Rambam Medical Center, Haifa, Israel.
Shofti
R
R
Beyar
M
M
Lichtig
H
H
Mordechowitz
D
D
Globerman
O
O
Markiewicz
W
W
Beyar
R
R
D000497:Alloys; D000818:Animals; D017023:Coronary Angiography; D003331:Coronary Vessels / Q000473:pathology / Q000502:physiology; D004285:Dogs; D004867:Equipment Design; D006965:Hyperplasia / Q000473:pathology; D015607:Stents; D013997:Time Factors; D017539:Tunica Intima / Q000473:pathology; D014654:Vascular Patency / Q000502:physiology
D000497:Alloys; C013616:nitinol