Accurate deployment of vena cava filters: Comparison of intravascular ultrasound and contrast venography

Background: The increasing use of vena cava filters by trauma surgeons has led to reports of filter placement using intravascular ultrasound (IVUS), A lthough attractive because of its ease of use and elimination of contrast a nd radiation, no studies have examined the accuracy of filter placement by IVUS as compared with contrast venography (CV), The purpose of this study w as to compare the anatomic information obtained by both techniques during f ilter placement. Methods: Twenty-one patients meeting trauma service criteria for filter pla cement were studied (11 women and 10 men; mean age, 46.8 years). All proced ures were performed in the operating room by trauma surgeons. Vascular acce ss was obtained by percutaneous placement of an 8 French sheath in the righ t femoral vein. CV, IVUS, and bilateral selective renal venography were per formed before deployment of a Greenfield filter, Localization and diameter measurements were made in reference to a radiopaque ruler placed on the pat ient's abdomen. We chose the "best location" for filter deployment as 1 cm below the junction of the lowest renal vein and the vena cava. Measurements by CV and IVUS were compared with the "gold standard" of selective renal v enography. Results: As compared with selective renal venography, the difference betwee n best location by CV and IVUS was 16.3 +/- 13.8 mm and 3.7 +/- 5.6 mm, res pectively (p = 0.001), In four cases (19%) the CV missed best location by 3 cm or more. CV overestimated the diameter of the vena cava in all cases. A verage vena cava diameter was 26.4 +/- 3.3 mm by venography and 20.6 +/- 3. 1 mm by IVUS (p < 0.0001), CV incorrectly identified four patients as havin g vena cava diameters too large (>2.8 cm) for the placement of a Greenfield filter. The two renal vein anomalies (one double left renal vein and one a bsent left renal vein) were correctly diagnosed by IVUS, Conclusion: IVUS is a more accurate method of localizing the renal veins an d measuring vena cava diameter for placement of vena cava filters than cont rast venography.