Experimental study of a new retrievable stent in inferior vena cava

Objective To evaluate the feasibility and safety of the implantation and recovery of a new retrievable inferior vena cava stent by animal experiment, and to provide evidence for further clinical application. Methods A total of 24 miniature pigs were divided into four groups randomly according to the observation time (3, 7, 11 and 15 days) after the retrievable inferior vena cava stent was deployed, with 6 pigs in each group. The retrievable stent placement was performed under general anesthesia via the right jugular vein with the right hepatic vein covered by the stent. Angiography of inferior vena cava and right hepatic vein and measurement of right hepatic vein pressure was conducted before and after the stent was released. On the basis of a pre-determined time, the retrievable inferior vena cava stent was removed. Right hepatic vein pressure was measured before the stent was taken out. Inferior vena cava and right hepatic vein were evaluated by venography before and after the stent was removed. The tissue of vessel with stent placement underwent pathological examination. Results Twenty-four stents were successfully implanted in inferior vena cava of the animals, the technical success rate was 100%, and all stents expanded great. For comparison of right hepatic vein pressures measured at different time points within the group, there was no significant difference (F=0.17, P>0.05; F=0.41, P>0.05; F=0.50, P>0.05; F=0.62, P>0.05). Stents were successful retrieved at 3rd and 7th day. It was difficult to retrieve the stents at 11th and 15th day after implantation. Under the microscopic examination, the thickness of neo-endothelialization of the inferior vena cava segments where the stent was implanted was (41.82±7.15), (200.32±66.67), (416.32±21.22) and (646.38±37.53) μm respectively, which had statistically significant difference among the four groups (F=260.52, P<0.01). The proliferating cell nuclear antigen (PCNA) mean optical density was (8.25±1.63), (19.77±3.59), (40.52±5.23) and (59.38±3.58) respectively in four group, with the difference being significant among four groups (F=209.46, P<0.01). Conclusion The retrievable inferior vena cava stent is safe and feasible to implant in the animal model, it will not change the hemodynamics of hepatic vein in the short term and can be safely retrieved within 7 days after implantation. Key words: Inferior vena cava; Retrievable; Stent