Tilt and caval penetration among permanent and retrievable inferior vena cava filters of similar design

Abstract

Purpose: The goals of this research were to compare tilt and caval penetration rates of the Günther Tulip (Cook Medical, Bloomington, IN) and Greenfield (Boston Scientific, Marlborough, MA) inferior vena cava (IVC) filters, and assess the difficulty of Tulip retrieval based on filter tilt, dwell time and caval wall penetration. Methods: Institutional review board approval was granted for this study, IRB #18-003517. Informed consent was waived by the institutional review board. This retrospective study reviewed Greenfield filter placement (n=26) and Tulip filter (n=203) removal. The electronic medical record was reviewed and a single author determined filter angle and caval penetration on the most recent available CT or catheter venogram. Filters removed with a snare were analyzed as routine removal and filters requiring additional devices or procedures were placed in a difficult removal group. Results: Greenfield filters had longer dwell time with a mean ± standard deviation of 811.3 ± 1398.1 days compared to 183.8 ± 262.1 days for Tulip filters (p=0.845). Filter tilt angle was not significantly different between the filter types 7.2 ± 4.7 for Greenfield filters and 5.5 ± 4.8 degrees for Tulip filters (p=0.09). Four (15.4%) Greenfield filters and 47 (23.2%) Tulip filters penetrated the caval wall >3 mm (P=0.37). Of the Tulip filters, those in the difficult removal group had a mean tilt of 7.6 ± 6.5 degrees compared to 4.6 ± 3.6 degrees in the routine removal group (p=0.0057). Conclusion: Greenfield IVC filters with longer dwell times demonstrate similar degrees of filter tilt and caval penetration as Tulip filters. A mean tilt of 7.6 ± 6.5 degrees indicates a filter which may require additional or alternative techniques for removal. *Correspondence to: Misra S, MD, FSIR FAHA, Professor of Radiology, Mayo Clinic, Department of Radiology, 200 First Street SW, Rochester, MN 55905, USA, Tel: 507-255-7208; Fax: 507-255-7872; E-mail: misra.sanjay@mayo.edu Received: November 04, 2019; Accepted: November 15, 2019; Published: November 18, 2019 Introduction Inferior vena cava (IVC) filters are commonly placed in patients at risk for pulmonary embolism (PE) or who have PE and a contraindication to anticoagulation, have failed anticoagulation, or have had a complication related to anticoagulation [1]. Over the past several decades, there have been numerous iterations to the IVC filter design and conically-shaped IVC filters are currently the most commonly used type of filter [2]. Permanent filters have largely been replaced by retrievable filters due to increased risk of lower extremity thrombosis associated with prolonged permanent filter dwell time [1,3,4]. Filter-related complications include caval wall penetration, IVC thrombosis, and in some cases, retrievable filters cannot be safely removed due to hook contact with the caval wall or strut penetration through the cava [1,5-7]. These issues tend to be magnified by the degree of filter tilt and duration of dwell time [8]. Although similar potential complications exist between permanent and retrievable filters, permanent filters are associated with fewer device related complications [7,9]. The purpose of this study was to compare IVC filter tilt and caval penetration rates of the similar, conically shaped permanent Greenfield (Boston Scientific, Marlborough, MA) filter and the retrievable Günther Tulip (Cook Medical, Bloomington, IN) filter, as well as evaluate the impact of tilt and penetration on retrievability of Tulip filters. Methods Institutional review board approval was granted for this single institution, retrospective review, and the study was compliant with the Health Insurance Portability and Accountability Act. Informed consent was waived by the institutional review board.