可回收下腔静脉滤器预防肺栓塞实验研究

目的：评价新型可回收下腔静脉滤器(RNIVCF)的稳定性、血栓捕获能力、可回收性及安全性。方法：体外实验评定RNIVCF捕获直径2．5、3和4mm混合血栓的能力。实验犬12只，10只经股静脉注入直径2．5mm自体不透X线混合血栓，评价RNIVCF血栓捕获能力；2只在置入RNIVCF后第7天尝试取出。摄腹部及胸部平片验证滤过效果。结果：体外实验证实RNIVCF捕获了直径3和4mm混合血栓的100%，直径2．5mm混合血栓的95％～100％。成功地在12只犬下腔静脉(IVC)经皮置入13枚RNIVCF，其中1只犬为双IVC，置入2枚滤器。lO只犬体内的11枚RNIVCF成功地捕获了经股静脉注入的直径2．5mm的混合血栓，无一死亡。2枚滤器在置入后第7夫经皮回收没有困难。结论可回收滤器既可以长期留置，又可以临时置入，更为实用。优点：①可经皮经5F输送器置入及回收；②滤器无钩刺，对腔静脉壁无损伤；③置入后稳定；④捕获小血栓有效。

Preliminary experimental study of retrievable nitinol inferior vena cava filter

Objective To evaluate, in vitro and in an animal model together with the placement, stability, clot capturing efficacy, retrieval and safety of a new non-invasive retrievable nitinol inferior vena cava filter (RNIVCF) for temporary or permanent use. Methods RNIVCF were made by wrapping nitinol monofilament wire on a steel mandril to form a steric configuration. A 5-F Teflon sheath/dilator was taken for placement and retrieval. In vitro clots' trapping was assessed with size of 2. 5/3/4 mm-diameter clots. Twenty adult mongrel dogs were used in this study. 2. 5-mm-diameter homologous radiopaque clots (2.5-mm-HRC) were injected into IVC until the experimental animals die of acute pulmonary embolism (PE) and then to determine the minimum fatal quantity of clots in 8 dogs. RNlVCFs were introduced into the inferior vena cava in 12 dogs. For 10 animals, 10-ml 2. 5-mm-HRC were injected below the filter to test its thrombus-trapping efficacy. The retrieval of filter was attempted on the 7th day after placement in two other dogs. Plain films of the abdomen and chest were made to document the effectiveness of the filter. Results Initial experimental study showed that the RNIVCF functioned as intended. In vitro all 3 and 4-mm-diameter clots injected in the device simulating IVC flow was trapped by the filter. However, 95%-100% 2. 5-mm-diameter clots were also captured by it. More than 10-ml 2.5-mm-HRC with once injection into IVC could cause the death of experimental animals due to acute PE in per-experiment. RNIVCF could be easily and successfully placed percutaneously in the inferior vena cava of the dogs through a 5-F sheath. The filter was accurately positioned in the inferior vena cava by moving the retrieval wire. All 13 RNIVCFs were placed in 12 dogs, one of those has double inferior vena cava and two filters were implanted. The filters trapped these 2. 5-mm-diameter clots in the iliac veins of 8 dogs and none of them died of acute PE. But the initial two dogs with two original RNIVCF died of acute PE due to hypertension of the inferior vena cava below the filters caused by injecting too much clots to force the trapped clots passing through the filters. Therefore, only 10-ml clots was necessary for injection into each the IVC of the dogs and thus the stabilized portion of the original RNIVCF can change into three-petals-quincunx shape. Two filters were retrieved successfully through the sheath/dilator in the 7th day after placement without difficulty. Conclusion RNIVCF is a kind of sophisticated device for retracting emboli. It can be sited percutaneously with 5F delivery permanently or temporarily in stable condition. The smooth contours cause no traumatic effect especially for retrieving small emboli.