Retrieval of overdue retrievable inferior vena cava filters
Feng Xiang, Department of Vascular Surgery, Changhai Hospital, Shanghai, China Retrievable inferior vena cava filters have become the mainstay of inferior vena cava filters because of their ability to capture thrombus at the risk of pulmonary embolism and to avoid complications associated with permanent implantation. However, it often happens that some patients miss the deadline for filter removal due to other problems during the treatment process. In such cases, the retrievable filters were often kept in the patient as permanent filters, thus completely eliminating the advantages of retrievable inferior vena cava filters. Recently, we have made some attempts to recycle these filters that have exceeded the expiration date of the use instructions for various reasons, which are summarized as follows. Feng Xiang, Department of Vascular Surgery, Shanghai Changhai Hospital
I. Materials and methods
1. Case data
From January 2009 to June 2012, a total of 6 patients were operated for the recovery of overdue retrievable inferior vena cava filters, and the basic conditions of the patients are shown in the following table.
Table 1, basic patient profile
Serial number
Sex
Age (years)
Filter implantation time (days)
Filter brand
Primary morbidity
1
Male
61
140
Günther Tulip
Pelvic fracture + DVT of right lower extremity
2
male
45
48
OptEase
DVT+PE of left lower extremity
3
Male
38
56
OptEase
DVT+PE of left lower extremity
4
Male
34
61
OptEase
DVT of the left lower extremity after prostate cancer surgery
5
Female
32
59
OptEase
DVT of left lower extremity
6
Female
70
120
Günther Tulip
DVT+PE of the left lower extremity
2. Status of the filters used
In 2 of the 6 cases (case 1 and case 6) using Günther Tulip (Cook Medical, Bloomington, IN), the filters were implanted for 140 and 120 days, respectively, while the maximum retrievable period of the product instructions was 20 days; in 4 cases using OptEase (Cordis Corporation, Bridgewater, NJ) in 4 cases, the average implantation time was 56 days, while the maximum retrievable period of the instructions was 23 days. All patients missed the filter retrieval time limited by the product’s instruction manual due to treatment of primary disease or DVT recurrence.
3.Surgery method
The retrieval procedures were performed under X-ray fluoroscopy.
In 2 cases, the Günther Tulip was recovered via the right internal jugular vein. The patient was lying flat on the DSA bed, the right neck was anesthetized by local infiltration, the internal jugular vein was punctured, the guidewire guided the catheter to the distal end of the inferior vena cava filter, the imaging showed no tilt of the filter and no large thrombus attachment, the rigid guidewire was exchanged, the 10F retrieval sheath and EV3 loop sleeve were fed, the filter retrieval hook was captured and the retrieval sheath was pushed downward to retrieve the filter into the sheath, the retrieval sheath was fixed and the filter was removed, and the inferior vena cava was re-imaged.
In all four cases, OptEase was retrieved by puncture through the right femoral vein, and the technique was the same except that the retrieval direction was opposite to that of the Günther Tulip filter.
II. Results
Two of the four OptEase cases were successfully retrieved, while one case encountered greater resistance during the retrieval of the filter into the sheath, and the inferior vena cava was found to be transiently stenosed by about 60% in the filter anchorage area after successful retrieval. In one case, repeated attempts to retrieve the filter were met with greater resistance, and the filter could not be completely retrieved into the sheath. The distal end of the filter was partially retracted into the retrieval sheath during the upward delivery of the retrieval sheath, but the patient felt unbearable back pain at this time. The inferior vena cava was completely blocked when the distal part of the filter entered the retrieval sheath, and the inferior vena cava blood flow entered the collateral vessels. In this case, the retrieval was abandoned, and the patient’s pain was relieved after 2 minutes of relaxation, and the inferior vena cava was restored to patency with no movement of the filter on repeat CT (Figure 1). On repeat CT, the filter was not displaced, the inferior vena cava was patent, and the anchoring struts of the filter were completely encapsulated by the inferior vena cava wall (Figure 2).
A B
C D
Figure 1 Failure of retrieval of a retrievable filter.
A Pre-recovery imaging is a well-positioned filter with patency, no tilt, and no large thrombus attachment.
B Increased resistance of the distal end of the filter into the retrieval sheath and inability to fully retract into the sheath.
C A partial sheathing of the filter shows a complete blockage of the inferior vena cava.
D The retrieval is abandoned and the inferior vena cava is restored to patency on repeat imaging.
A B
Figure 2 CT review after failed retrieval
A No displacement of the filter, patency of the inferior vena cava, and no peripheral exudate.
B The anchoring strut of the filter has been completely encapsulated by the endothelium of the inferior vena cava.
III. Discussion
The therapeutic concept of blocking thrombus emboli at the inferior vena cava to avoid pulmonary embolism (PE) has been around for more than 100 years, and the highly invasive inferior vena cava ligation was accepted by many physicians and patients because of its perceived benefit in preventing PE. As a result, the relatively non-invasive vena cava filter became accepted very quickly upon its appearance, and in the 20 years from 1979 to 1999, the use of inferior vena cava filters in the United States increased 20-fold [1,2,3]. In the last decade, the development of evidence-based medicine has called into question the role of vena cava filters in the prevention of PE and, with the recognition of vena cava filter complications, the indications for vena cava filter implantation have become more stringent [4,5]. However, the use of vena cava filters continues to increase, as data, also from the United States, show that the market for vena cava filters in the United States was worth $200 million in 2007 and is estimated to reach $300 million in 2012 [6], with much of this growth coming from the promotion and use of recyclable filters in recent years.
The natural course of venous thrombosis exposes patients to the threat of PE only for a period of time after the formation of DVT in the lower extremities, so the need for PE prevention is only temporary, meaning that even if vena cava filters are very effective in preventing PE, the need for them is only temporary. The previous permanent filters exposed patients to the need for long-term anticoagulation and the possibility of inducing inferior vena cava thrombosis, making them suffer from PE for a long time after getting rid of the short-term threat [7]. Therefore the concept of temporary or retrievable filters emerged. One is the temporary filter that must be retrieved, represented by the Tempfilter II from B. BRAUN, which is designed with a catheter attached to the proximal end of the filter, and the end of the catheter is fixed under the skin of the neck after implantation. The disadvantages are the possibility of catheter thrombosis, displacement to the proximal end, infection, and patient discomfort caused by the indwelling catheter; the second type is called the temporary and permanent dual-use filter, i.e., the retrievable inferior vena cava filter, whose structure is similar to the previous permanent filter but with a retrieval hook, which can be retrieved through the sheath and trap, and there is a wide variety of these products, but the manufacturers’ recommended retrieval period is generally within one month [8].
Retrievable inferior vena cava filters have become the mainstay of inferior vena cava filters because they can capture thrombus during the risky phase of pulmonary embolism and avoid the complications associated with permanent implantation of the filter. However, a study by the American Association for Trauma Surgery of 446 patients with prophylactic implantation of retrievable filters found that only 22% of the filters were retrieved on time [9]. There are many reasons why retrievable filters are not retrieved on time, including patients still at risk for PE and need to be left in place longer, the filter captures a large volume of embolus, the filter tilts or adheres to the vena cava wall making retrieval difficult, the patient is missed after surgery or the patient does not want to reoperate, etc. For these patients who have missed the deadline for filter retrieval as defined in the product instructions for various reasons, the majority of retrievable filters have been kept in the patient’s body as permanent filters, thus completely eliminating the benefits of retrievable filters, but there are many attempts to retrieve expired retrievable filters that continue to challenge the record.
A review of the literature reveals a number of records for the longest time a retrievable filter has been in a patient: the Günther Tulip was removed after 494 days of implantation, the OptEase was removed after 59 days of implantation, the G2 (Bard Peripheral Vascular, Tempe, AZ) was removed after 1,463 days of implantation, and the Celect (Cook Medical) was removed after the longest time. Celect (Cook Medical) was removed after a maximum of 466 days and ALN (ALN Implants Chirurgicaux, Ghisonaccia, France) after a maximum of 722 days [10,11,12].
The above cases were not attempted simply to satisfy the patient’s wish to remove the filter, ignoring the recall period specified in the product’s instructions for use. The issue of OFF-LABEL USE of interventional devices has been a constant issue both domestically and internationally, and in many cases has been a source and motivation for new product development. However, in order to ensure patient safety, exploring the recovery of over-life recyclable filters requires an understanding of several issues.
First, we need to understand why retrieval of retrievable filters is time-limited. When a filter is implanted in the inferior vena cava, the anchor points of the filter are in contact with the wall of the inferior vena cava, and most filters also have a barb-like design that prevents displacement proximally. These contact points cause damage to the endothelium of the vena cava, which will be covered by the re-formed endothelium after a certain period of time [13]. The larger the area of the contact point, the larger the area covered by endothelium, and the greater the resistance to recovery. The time to complete the reendothelialization of vascular injury is generally about 3 months, and the more complete the endothelialization, the more the filter is fixed, and the greater the resistance to filter recovery. Therefore, within one month of the vena cava filter being implanted, the filter is only mechanically fixed and not encapsulated by the new endothelium, which is the main reason why most retrievable filters are required to be retrieved within one month.
Next, we need to understand what improvements have been made to the retrievable filters compared to the permanent filters. Most manufacturers’ recyclable filters are improved from the original permanent filters. One is the addition of a recovery hook, which is necessary for recovery; the other is that most of the anchoring points of the retrievable filters use pillars parallel to the axial direction (e.g., Cordis’ OptEase) or upper and lower support points (e.g., COOK’s CELECT) to ensure that the axial direction of the filter is parallel to the inferior vena cava after implantation, thus avoiding the difficulty of recovery caused by the tilted recovery hook against the wall of the filter [14, 15]. difficulties in recovery [14, 15]. These two different methods of maintaining the axial orientation of the filter determine the difference in the area of contact with the vena cava wall, which leads to a different magnitude of recovery resistance, and it is clear that the strut type anchorage device results in greater resistance to recovery when it is embedded by the endothelium. Therefore, if it is estimated that the patient will need filter protection for a longer period of time, a filter with a point anchorage point should be used instead of a filter with a pillar anchorage point.
Finally, we need to understand the rationale for the manufacturer’s filter recall period. There is no doubt that the data comes from animal and clinical trials, but it should be noted that the filter manufacturer must get very safe data in clinical trials in order to successfully obtain certification, in other words to get very low complication rate data in the case of a new product launch when most doctors do not have much experience in using it. According to our analysis above, we can know that the shorter the implantation time of the filter, the lower the resistance to recovery and the lower the operational complication rate. Therefore, the recovery period set by the manufacturer needs to ensure a safe and smooth recovery for each physician, and most of the overdue filters are not difficult for experienced physicians to recover.
From the above analysis, we can conclude that, firstly, most of the current retrievable filters have a limited retrieval time of less than one month, which is not enough to meet the needs of all patients, and many patients turn their retrievable filters into permanent ones simply because they miss the retrieval deadline. Third, the difficulty of retrieving retrievable filters differs slightly from structure to structure, so if you consider the possibility of retrieval before implantation, you should choose a brand that is easier to retrieve.