Detection and Correction of Anterior or Posterior Tilting of the Günther-Tulip Filter in the Inferior Vena Cava and Correction by Repositioning: A Phantom Study and Preliminary Clinical Experiences

Purpose: To evaluate the features of the Günther-Tulip filter (GTF) with or without tilting toward the anterior or posterior direction with use of phantom models and to describe our preliminary clinical experience to detect tilting and to reposition the GTF with regard to the maneuver's feasibility and usefulness. Materials and Methods: Two types of phantom models were made by inserting a GTF in a tube with or without tilting toward the anterior or posterior direction. Changes of the fluoroscopic features were observed in the postero-anterior projection. For the clinical trials, transjugular placement of the GTF in the inferior vena cava (IVC) was performed in 12 patients. As the result of the phantom study, repositioning of the filter was repeated until the four anchoring hooks stood on an imaginary line before releasing. Finally, cavograms were obtained and the angles were measured between the axis of the filter and the IVC axis and the coronal plane in the lateral projection. Results: In the phantom study, the four anchoring hooks stood in a transverse imaginary line when the filter without tilting was located at the center of the fluoroscopic projection. In the clinical trials, the mean number of repositionings was 1.67, and the mean angles between the axis of the filter and the IVC axis and the coronal plane in the lateral projection of the cavogram were 0.08 degrees ± 2.32 and 0.18 degrees ± 5.09, respectively. Conclusions: For placement of the Günther-Tulip filter, the maneuver to detect tilting and to reposition it was feasible and useful to prevent tilting seen after initial placement.