The timing for safe and uncomplicated retrieval of an IVC filter cannot be universally determined. However, in the setting of increasing reports of device-related adverse events, the FDA issued an alert in 2010, urging physicians responsible to retrieve the filter as soon as protection from pulmonary embolism (PE) was no longer needed. This alert was updated with a quantitative decision analysis model by Morales et al. in 2014 [10]. The model showed the risk of complications began to outweigh protective benefits of the filter at day 35 from implantation. Based on a sensitivity analysis, the authors suggested an ideal retrieval time between 29 and 54 days from implantation. In practice, several patient- and physician-related factors can delay significantly the timing of retrieval. Some patients have prolonged complicated hospital course and need for repeat surgeries especially after multi-trauma accidents [11]. Vascular specialists placing IVC filters may not have established algorithms for continuity of care resulting in loss to follow up. The creation of institutional mechanisms to capture patients after IVC filter placement has significantly improved and expedited their removal [12, 13]. In a recent survey of vascular specialists , 45% of responders who place IVC filters would not offer IVC filter removal after a dwell time of 2 years [14]. On the other hand, several case reports have described retrieval of IVC filters after extended periods from 3 years and up to 16 years from the time of placement [15–17]. Prolonged dwell time increases failure and complications of filter removal [8, 9]. Therefore, the decision of IVC filter removal and the technical strategy should be individualized based on patient’s symptoms, risk of recurrent VTE/bleeding, and local expertise.

Prior to retrieval of the IVC filter, patients are evaluated to assess for risk of recurrent VTE. This evaluation involves a focused history and physical, routine laboratory investigations focusing on renal function and coagulation profiles. The presence of signs and symptoms suggestive of new or recurrent VTE requires a full workup prior to IVC filter removal. The ambulatory status of the patient must be assessed prior to retrieval. In our practice, we do not remove IVC filters routinely from patients who are immobilized because of increased risk of VTE. The presence of DVT must be ruled out by obtaining venous duplex of the lower extremities prior to consideration for filter retrieval. If imaging performed reveals new or progressive VTE, filter retrieval must be deferred to a later date. However, these patients should be reevaluated for filter retrieval, upon completion of the appropriate anticoagulation regimen. We follow a modified version of the algorithm provided by the Society for Interventional Radiology (Fig. 33.1) [18]. A computed tomography (CT) scan of the abdomen and pelvis with intravenous contrast is warranted for patients with a filter dwell time over 1 year. Additionally, in our practice we routinely obtain CT scan of the abdomen and pelvis with intravenous contrast for retrieval of IVC filters that were placed at outside institution and referred for retrieval. Cross-sectional imaging is useful to determine the configuration and integrity of the filter, the presence of thrombus within the filter, and the location of the hook as well as penetration into surrounding structures. A grading system has been devised to better define the extent of strut penetration into the IVC wall [19] (Table 33.2). Filter tilt is measured as the angle between the axis of the filter and the axis of the IVC. The tilt is deemed significant when this angle is greater than 15° from long axis [20]. Filter migration can also be determined and is defined as a 2 cm or greater superior or inferior movement from initial placement location [20].

Standard retrieval of an IVC filter is commonly performed via right internal jugular vein access under ultrasound guidance. First, a venogram is performed to ensure that there is no thrombus trapped in the IVC filter. If more than a third of the cone has thrombus, we leave the IVC filter in situ to avoid “squeezing” and embolization of the clot to the lungs. A vascular snare or a retrieval cone system is introduced to grasp the hook of the filter. This is followed by advancing a vascular sheath over the snared filter to disengage the struts and collapse the filter (Fig. 33.2). Most filters have the apex or the “cone” directed cephalad and can be retrieved via a transjugular approach. However, certain filters have the hook placed caudally, requiring a transfemoral approach for retrieval. There are various kits and tools commercially available such as Recovery Cone Removal System (Bard Peripheral Vascular, Tempe, AZ), Günther-Tulip retrieval kit (Cook Medical Inc., Bloomington, IN), and ALN Optional Vena Cava Filter Extraction Kit (ALN Implants Chirurgicaux, Ghisonaccia, France). Filter retrieval can be performed with local anesthesia and sedation as outpatient procedure. When performed in a timely fashion after placement , successful retrieval can be achieved in 93% of the time as demonstrated in a recent randomized trial [21].

Filter removal involves two maneuvers: first, securing the filter and aligning it with the sheath and, second, collapsing it and freeing its tines from the IVC wall. As simple as it may seem, these two steps can be fraud with significant challenges transforming a simple procedure to a vascular specialist’s worst nightmare. Increased dwell time, filter tilt, and filter to caval wall apposition have been shown to be associated with failure of retrieval and increased complexity [8, 9]. Filter tilt without apposition to the wall of the cava typically does not prevent removal but makes it more challenging. The commercially available kits contain straight linear tools with inability to tilt or aim in a specific direction. Posterior tilt can be particularly deceiving, as the filter may appear to be centered on the anteroposterior fluoroscopy image. The operator can spend some time trying to capture the hook of the device without success. Oblique views are needed to visualize the tilt and direct the operator. Apposition of the filter to the wall makes the hook inaccessible, but erosion of the hook through the wall makes safe endovascular retrieval even more challenging (Fig. 33.3). Moreover, severe fibrosis around the tines of the filter can make the removal very hard. Significant force is needed sometimes that surpasses the maximal stress that the material of the filter or the retrieval device can tolerate before failure. Figure 33.4 illustrates a retrieval sheath that is accordioned from excess pressure while pulling on the filter and pushing the sheath (Fig. 33.4a). The filter was captured, but a tine was stuck and eroded through the sheath at the deformed zone (Fig. 33.4b). Filter and sheath had to be removed together. The filter was confirmed to be intact after cutting the sheath open and visualizing the filter (Fig. 33.4c). In another example, one of the tines was stuck in a lumbar vein and could not be disengaged easily. The force applied was excessive, resulting in a complete straightening of the filter hook (Fig. 33.5). The case was aborted because of patient discomfort. The filter was subsequently removed successfully during a second attempt under general anesthesia with dual access and wire-loop technique. These challenges led to significant creativity in the vascular community to use available tools, sometimes in an off-label fashion, for endovascular IVC filter removal. These methods will be referred to as advanced endovascular techniques and will be summarized in the next section.

In up to 20% of cases, standard endovascular retrieval is unsuccessful [7–9]. Over the years, numerous advanced techniques have been described for filter retrieval, in these complex scenarios [22–24]. The simplest modification of standard retrieval is when the sheath is upsized to a large-bore sheath (16 French), increasing the rigidity of the retrieval apparatus. Additionally, the snare can be introduced through an angled catheter, in cases with significant filter tilt. This simple maneuver permits for easy engagement of the apex in these situations.

These techniques incorporate the use of multiple wires, snares, and sheaths to engage the hook of filter and mechanically disrupt embedded struts of the filter. It is important to note that the characteristics of optional filters render them a higher risk for filter deformity, strut fracture, and strut migration. Hence, careful vigilance must be used while incorporating these techniques.