Objective To study the safety of the novel high nitrogen nickel-free austenitic stainless steel bare metal stents (BMS) in a recognized porcine coronary model and to select a better grid structure of it.
Methods Three types of stents were randomly implanted in different coronary arteries of the same pig: 316L stainless steel BMS (316L-BMS) (n=12), novel high nitrogen nickel-free stents Grid A (NF-A-BMS) (n=12) and novel high nitrogen nickel-free stents Grid B (NF-B-BMS) (n=12). In total, eighteen animals underwent successful random placement of 36 oversized stents in the coronary arteries. Coronary angiography was performed after 36 d of stents implantation. Nine animals were respectively sacrificed after 14 d and 36 d for histomorphologic analysis.
Results Quantitative coronary angiography (QCA) showed similar luminal loss (LL) in the three groups:(0.21±0.17) mm for 316L-BMS, (0.16±0.12) mm for NF-A-BMS, (0.24±0.15) mm for NF-B-BMS (P>0.05). Histomorphomeric analysis after 15 d and 36 d revealed that there was also no significant difference among the three groups in neointimal area (NA) with similar injury scores respectively. High magnification histomorphologic examination showed similar inflammation scores in the three groups, but NF-A-BMS group had poorer endothelialization scores compared with NF-B-BMS group, 2.00±0.63 vs. 2.83±0.41 (P=0.015) at 15 d, which also could be proved by the scanning electron microscope. However, the difference could not been observed at 36 d.
Conclusion The novel NF-BMS showed similar safety as 316L-BMS during the short-term study. NF-B-BMS had better endothelialization than NF-A-BMS and this may owe to the specific strut units.

Objective To investigate the delivery efficacy of periadventitial delivery of 125I-iododeoxyuridine (125I-IUdR) in comparison of intravascular delivery to determine the optimal delivery method for inhibiting post-angioplasty restenosis. Methods In 8 pigs, one side carotid, subclavian and iliac arteries of each pig were injured by balloon angioplasty with a 20% overstretches. Then, 4 mCi of 125I-IUdR was delivered at each targeted vessel with periadventitial method in 4 pigs (periadventitial group) and with intravascular method via a porous balloon catheter in other 4 pigs (intravascular group). The animals survived for 5 hours and the blood radioactivity was investigated prior to and hourly after procedure until sacrifice. The targeted vessels and renal arteries (for control) were harvested for gamma-counting and histological observation. Meanwhile, the radioactivity in thyroid, liver, bladder, small bowel and each kidney also were measured to determine the biodistribution of 125I. The activities of 125I presented in arterial and tissue specimens were compared between the two delivery groups. The targeted arteries were histologically observed and the ratio of intima to media (I∶M ratio) was calculated. Results The target arterial walls in the periadventitial group had 3.4 times as much of 125I radioactivity as in the intravascular group, respectively (P=0.038); the blood activity in intravascular group was significantly higher than periadventitial group immediate after procedure (P<0.05) and intravascular delivery resulted in much higher activity in urine than periadventitial delivery (P<0.05). The systemic biodistributions of 125I-IUdR in the organs were slightly higher in the intravascular group (P>0.05). The mean I: M ratios in both groups were 0.05 without additional injury at the vessel wall. Conclusion The periadventitial delivery offered substantial advantage over intravascular approach with high local delivery efficacy. The apparent redistribution rate is more rapid following intravascular delivery.

Objective　To study the efficacy and safety of cutting balloons in coronary interventions.Methods　Twenty-two patients with 23 narrowed coronary arteries and 25 lesions enrolled the study, 17 of whom had 18 diseased coronary arteries and 18 lesions were in-stent restenosis. The average time from previous stenting was 7.60±3.53 months. The lesions were dilated with cutting balloons. Results　All of the lesions were dilated successfully by 5.16±2.30 inflations of a cutting balloon. The mean total duration of balloon inflation was 233.96±94.83 seconds at pressures up to 9.40±1.96 bars. The severity of vascular stenosis was lessened substantially (89.64±8.65% vs 17.60±17.15%， P=0.000) without severe complications. Three restenotic lesions were further dilated with conventional balloons, another one was stented again because of a dissection distal to the previous stent. Three primary lesions were stented for dissection or residual stenosis. Angina pectoris reoccurred in two patients in a mean follow-up period of 7.42±6.87 (range 0.5-20) months. Conclusion　Cutting balloon dilation is an effective and safe choice in interventions for coronary disease especially for in-stent restenosis.

Ojbective To find the independent predictors for restenosis after coronary stenting.Methods Quantitative angiography was performed on 60 cases (67 successfully dilated lesions) after angioplasty over 6-months follow-up, and both univariate and multivariate logistic regression analysis were done to identify the correlations of restenosis with clinical factors. Results The total restenosis rate was 31.3％(21 of 67 lesions), and according to univariate analysis the patients who underwent coronary stenting ≥3.5mm had a lower rate of restenosis ( P ＜ 0. 01).Collateral circulation to the obstruction site, high maximal inflation pressure, smoking and the less minimal lumen diameter after PTCA made the rate of restenosis higherower ( P ＜ 0.05) . Multivariate logistic regression analysis showed that coronary stenting ≥ 3.5mm had a low rate of restenosis, but high maximal inflation pressure and smoking made the restenosis rate higher. Conclusion Coronary stent size, maximal inflation pressure and. smoking were independent predictors for restenosis.