In Reply to: Case 797_01 -- Incompletely formed nitinol filter posted by Editor on July 17, 1997 at 17:12:15:
We don't use this filter except in unusual circumstances, e.g. (as recently occurred) bilateral femoral vein thrombosis, neck brace in place covering right IJ, and need to go from the arm. I'm interested as to Dr. Kirsch's reasons for favoring the filter.
My inclination would have been to leave the filter as is--I would also worry about getting a snare stuck or tearing the cava with what may be (unintentionally) overly vigorous manipulations. I would have thought that the cross-sectional profile could have filtered quite adequately and am certainly interested in the suggestion by Scott Trerotola (suggested by the company representative) that this might not be the case.
I certainly would have been concerned about penetration of the caval wall by the filter leg, particularly given the acute nature of the finding. However, I would call everyone's attention to an exhibit presented at last year's RSNA by Procter et al from Ann Arbor which showed that what seemed to be obvious caval penetration on CT scans or ivc grams in fact did not represent gross penetration, at least for the Greenfield filter; instead, the legs were found to be in the adventitia or within scar tissue and there was evidence of some remodeling of the caval wall in the vicinity of the filter leg. This material was also presented at the 1997 SCVIR meeting. I don't know if tenting of the caval wall could produce a similar "pseudopenetration" in the acute setting.
By the way, can any etymologists out there explain to me why the words are "cavography" and "aortography" rather than "cavagraphy" and "aortagraphy". One of those deficiencies in my education which I've not been able to resolve.