Division of Vascular Surgery, University of Utah School of Medicine, Salt Lake City, Utah 84132, USA.
J Vasc Surg. 2010 Oct;52(4):920-4. doi: 10.1016/j.jvs.2010.05.013. Epub 2010 Jul 13.
In July 2007, our group began to use a modified conical inferior vena cava filter with additional stabilizing struts designed to reduce tilting of retrievable filters. We analyzed our experience with this modified filter (Cook Medical, Bloomington, Ind) from July 1, 2007 to December 31, 2008 and compared it to our experience with the standard filter (Günther Tulip, Cook Medical, Bloomington, Ind) from January 1, 2006 through December 31, 2008 to determine if adoption of the modified filter reduced tilting and delivered a discernible clinical benefit.
The primary outcome measure was tilt angle after deployment. Secondary outcomes were change in tilt angle between deployment and retrieval (self-centering) and retrieval failure due to inability to engage the filter hook. Measurements were retrospectively determined using the anteroposterior venogram at the time of placement and removal. Tilt angle was defined by the center line of the filter relative to the center line of the inferior vena cava (IVC). Statistical significance was assumed for P ≤ .05.
During the study period, a total of 302 IVC filters were placed. Retrieval was attempted for 85 of 194 (44%) standard filters and 52 of 108 (48%) modified filters. The overall difference in tilt angle (degrees) between the standard (median [interquartile range] = 5 [3, 8]) and modified (5 [3, 8]) filters at the time of placement was not statistically significant (P = .44). Modified filters deployed through a femoral route (8 [4, 11]) had significantly greater tilt angles than modified filters deployed using jugular access (4 [2, 6]; P < .0001). At the time of retrieval, evidence of self-centering was observed more often with modified (32 of 52 [62%]) than standard (36 of 85 [42%]) filters (P = .03). Overall, there were only four failures to retrieve the filter due to excess tilting (standard, 3 of 85 [4%], modified, 1 of 52 [2%]; P = .59).
Overall, tilt angle at insertion did not differ between the modified and standard filters, although more modified filters displayed self-centering. There was no difference between the groups in retrieval failure due to excess tilting. Despite its greater tendency to self-center, we did not recognize a measurable clinical advantage of the modified filter.
2007 年 7 月，我们的团队开始使用一种改良的锥形下腔静脉滤器，该滤器增加了稳定支柱，旨在减少可回收滤器的倾斜。我们分析了从 2007 年 7 月 1 日至 2008 年 12 月 31 日期间使用这种改良滤器（库克医疗公司，印第安纳州布鲁明顿）的经验，并将其与 2006 年 1 月 1 日至 2008 年 12 月 31 日期间使用标准滤器（库克医疗公司，印第安纳州布鲁明顿的 Günther Tulip）的经验进行比较，以确定采用改良滤器是否减少了倾斜并带来了明显的临床益处。
主要的结局测量指标是植入后的倾斜角度。次要结局指标为植入和取出期间的倾斜角度变化（自对准）和因无法钩住滤器而导致的取出失败。使用植入和取出时的前后位静脉造影来回顾性确定测量值。倾斜角度通过滤器的中心线相对于下腔静脉（IVC）的中心线来定义。假设 P≤0.05 具有统计学意义。
在研究期间，共放置了 302 个 IVC 滤器。尝试取出 194 个标准滤器中的 85 个（44%）和 108 个改良滤器中的 52 个（48%）。标准（中位数[四分位距] = 5 [3, 8]）和改良（5 [3, 8]）滤器在植入时的总体倾斜角度（度）差异无统计学意义（P =.44）。通过股静脉途径植入的改良滤器（8 [4, 11]）的倾斜角度明显大于通过颈内静脉途径植入的改良滤器（4 [2, 6]；P<0.0001）。在取出时，与标准滤器（36 个中的 32 个[42%]）相比，改良滤器（52 个中的 32 个[62%]）更常出现自对准现象（P =.03）。总体而言，只有 4 个滤器因过度倾斜而无法取出（标准，3 个中的 3 个[4%]，改良，1 个中的 1 个[2%]；P =.59）。
总体而言，改良滤器和标准滤器在插入时的倾斜角度没有差异，尽管更多的改良滤器显示出自对准。由于过度倾斜而导致的取出失败在两组之间没有差异。尽管改良滤器有自我中心的趋势，但我们没有发现改良滤器有可衡量的临床优势。
