| Objective To assess the feasibility and safety of implantation homemade stents of surface modification, and their influence of stents on neointimal proliferation, to supply the evidence for further experimental or clinic trial. Data and Methods 1.Experimental animals and pretreatment Fourteen Chinese experimental minipigs were divided into two groups randomly (n=7 in each group)—experimental group and control group. The minipigs had been forbidden to drink and eat for 12 hours before coronary angiography. Before and after operation, the minipigs were fed with common corn . 2.Stents and delivering system A custom-made stainless steel, slotted-tube stent(Jinxin stent, developed by the Metal Institute of Chinese Academy of Science and Liaoning provincial hospital's cardiac intervention center)of 15 mm length and 3.0 mm expanded diameter was used in the present study. The stent was crimped manually on a 3.0 mm balloon catheter before operation and it could be expanded to expected diameter when the balloon was inflated with 6~8 atm .The length of balloon used were 18 mm. To produce the stent of surface modification, the Jinxin stent was coated with titanium, and then titanium oxide/ titanium nitride films were performed by ion beam enhanced deposition on titanium in a vacuum chamber. 3.Stent implanting After anesthesia and skin degerming, femoral artery was dissected and punctured. Heparin sodium (200 IU/kg IV) was administered. The stent was implanted in a selected coronary segment with a vessel diameter of 2.5~3.0 mm. The balloon had been inflated with 10~15 atm for 15 seconds to overstretch the coronary by a balloon-to-artery ratio 1.1~1.3. The stents of surface modification were implanted in the artery of minipigs of experimental group, while the Jinxin stents were implanted in the artery of minipigs of control group. 4.Angiography analyses Quantitifying Coranary Angiography(QCA) was performed before stent implanting, instantly and three months after stent implanting. The minimal lumens diameter (MLD) of coronary stent edge was examined. The instant gain was calculated as the difference of MLD instantly after stent implanting and before stent implanting. The late loss was calculated as the difference of MLD instantly after stent implanting and MLD 3 months after stent implanting. 5.Histological examination The minipigs were sacrificed after 3 months follow-up and repeating coronary angiography. The stented coronary segments were analyzed on a digital system for quantitative histomorphometry. The cross-sectional areas of the intima, media and lumen, and injury score were determined. The intima was defined as the area between the endothelial lining and the internal elastic lamina, the media as the area between the internal and external elastic lamina, and the luminal area as the area circumscribed by the endothelial layer. Neointimal thickness was determined by calculatingthe ratio of neointimal area and internal elastic lamina circumference. Media thickness was determined by calculating the ratio of media area and external elastic lamina circumference. 6.Statistical Analyses Continuous numerous variables were expressed as mean value ± SD. Differences in experimental group and control group were assessed by independent samples t-test. SPSS 10.0 statistics software was adopted. A value of P<0.05 was considered statistically significant. Results 1 . Seven stents were implanted in minipigs' coronary arteries successfully in each group. One minipig died from pneumonia after operation. Adverse cardiac events haven't been observed in both groups. 2.The MLD of experimental group and control group were (2.83±0.21) mm and (2.78±0.21) mm (P=0.71) before stent implanting; (3.13±0.22) mm and (3.07±0.37) mm (P=0.72) instantly after stent implanting; (2.79±0.32) mm and (2.62±0.17) mm (P=0.28) 3 months after stent implanting. Instant gain were (0.30±0.28) mm and (0.28±0.25) mm (P=0.91) in two groups, while late loss were (0.34±0.38) mm and (0.45±0.39) mm (P=0.63). No stenosis and thromb...
|
PDF Full Text Request