滤器直径与下腔静脉穿通程度相关性的实验研究

Placing a filter into inferior vena cava (IVC) has been an effective method against fatal pulmonary embolism. The inserted filter may cause IVC penetration, some of which being clinically significant with the surrounding structural injuries. The clinical practice calls for researches with focus on how to reduce this filter-related complication. The mismatch between filter's diameter and caval caliber may contribute to this complication. The filter or the components of filter may penetrate caval wall if an oversized filter is placed in a relatively small IVC. However, the hypothesis has not been well verified. Consequently, the present study aims: (1) to study the morphology of infrarenal IVC (length, caliber, and collapsibility) under different respiratory phases in miniature pig using dual-source CT, and to establish a set of key imaging techniques for preoperatively evaluating the morphology of infrarenal IVC; (2) to study the radial force' response to one type of filter with different oversize ratio (OR);(3) to experimentally study the prevalence and severity of real IVC penetration attributed to mismatched OR of a filter and finally to attain an optimal OR value of a filter for safe placement. We attempt to further verify the correlation between the OR value of a filter and the severity of IVC penetration, to propose the optimal OR value for safe placement of a filter and thereby to reduce the rate of IVC penetration. Meanwhile, the present study may theoretically and basically help to promote the design of a filter, and clinically help a doctor to precisely and individually use a filter with the optimal OR.

下腔静脉滤器置入是预防发生致死性肺动脉栓塞的有效方法。滤器置入下腔静脉后，可发生下腔静脉管壁穿通，导致周围组织和结构损伤。如何降低滤器腔静脉穿通风险，已成为临床迫在眉睫的课题。滤器直径和腔静脉内径之间不匹配可能是发生该并发症的主要原因：当滤器直径过大，腔静脉内径偏小时，滤器支脚的径向力增大，即可能发生滤器穿通腔静脉。但该假说尚未得到实验证实，为此开展本研究：（1）以小型猪为实验对象，研究不同呼吸时相下的猪肾下段下腔静脉形态（长度、内径、塌陷率等），建立评价下腔静脉形态的关键影像学技术；（2）以点接触滤器为对象，研究滤器直径放大率和滤器径向力的相关性；（3）研究不同滤器/下腔静脉内径比率下，发生滤器真性穿通的比率及程度，得到滤器的最佳直径放大率。旨在明确滤器直径放大率与腔静脉穿通程度的相关性，提出点接触滤器的最佳直径放大率值，以期降低腔静脉穿通的发生率；同时为滤器的改良和创新提供理论基础。

下腔静脉滤器是预防致死性肺动脉栓塞的有效方法和手段，但随着滤器置入患者人数日渐增多，与滤器相关的并发症，如滤器断裂、下腔静脉穿通等并发症发生率也随之增高。滤器穿通下腔静脉管壁的机制尚未系统阐明，根据现有研究推测下腔静脉管径和滤器形态学不匹配是发生滤器穿通下腔静脉管壁的主要机制之一。本课题通过一系列的实验研究，重点探讨滤器直径与下腔静脉穿通程度之间的相关性。初步研究结果提示：选取小型猪为实验动物，以双源CT为主要工具，研究不同呼吸时相下的猪肾下段下腔静脉形态（长度、内径、塌陷率等）是可行的。以点接触滤器为主要研究对象，研究在滤器不同直径放大率下，滤器支脚径向力的变化，初步研究结果提示：滤器支脚径向力与直径放大率呈正相关。采用动物实验，研究滤器不同直径放大率下，发生滤器真性穿通的比率及程度（与组织病理学对照），计算滤器的最佳直径放大率，初步研究结果提示：滤器直径过大，腔静脉内径偏小，是发生滤器穿通腔静脉的重要原因。初步研究结果提示：滤器穿通下腔静脉管壁后，静脉内膜可出现增生改变，外膜可变薄，滤器穿通处可见纤维组织包裹。我们的研究结果有一定的科学意义，通过上述系列研究，明确滤器直径与发生滤器穿通腔静脉的相关性，提出点接触滤器的最佳直径放大率值，达到既能防止滤器移位，又能降低滤器穿通腔静脉发生率的目的；同时为滤器的改良和创新提供理论基础，为临床个体化、精准化使用滤器提供理论支持。