Common Indications and Retriever of IVC Filter Placement in Nigeria: Three Case Series

There are many reasons for Inferior Vena Cava (IVC) filter placement. Even with the expanding lists of indications, most guidelines recommend that contraindications to systemic thrombolysis or its failure may necessitate IVC filter placement. The increased use may be due to the insertion of retrievable filters. We report three cases with indications for IVC filter placement.


Introduction
IVC is a vein that carries deoxygenated blood from the lower limbs, pelvic and abdominal organs to the heart. According to the recommendations of American Society of Echocardiography (ASE) guidelines and European Association of Echocardiography (EAE), the IVC was described as small when the diameter was <1.2 cm, normal when the diameter measured between 1.2 and 1.7 cm and dilated when it measured >1.7-2.5 cm, markedly dilated when it >2.6 cm. [1,2] The commonest source of pulmonary embolism is deep vein thrombosis (DVT) from the lower limb and the pelvic region [3]. An IVC filter is one method that helps prevent pulmonary embolism. In this 3 case series, we report the common indications for inferior vena cava (IVC) filter placement in Nigeria.

Case 1
Mr This was followed by emergency upper GI therapeutic endoscopy with an injection of sclerosant on the stomach ulcer. The patient was then transferred to our cardiac catheterization laboratory for inferior vena-cava filter implantation. Warfarin was stopped. Pre-procedure inform consent was taken. Packed cell volume after the 12 units of blood was transfused was 23% and Hb 7.0g/dl, Na was 141mmol/dl, K was 3.8mmol/dl, urea was 3.9mmol/dl and creatinine was 72µmmol/dl. He was counseled on the complications of IVC filter including fracture and embolization, thrombogesis, migration, and penetration.
Procedure: The right groin was prepared with a butadiene solution in sterile technique. This was followed with 10mls of 2% lignocaine after draping the patient. The common femoral vein was accessed via blind puncture and the guide wire passed to the right common iliac vein. The intra-renal segment of the IVC was located with an injection of 20 MLS of omnipaque. This was to visualize the renal vein and the IVC diameter (24mm).
The IVC filter (7F sheath, ALN IVC filter) was placed at L 3, (an intra-renal segment of the inferior vena cava). (see figure 1). The procedure was uneventful.
Post-procedure: He was transfused with 3 more units of packed cells. IV antibiotics and omeprazole continued in the hospital for 1 week. He was discharged home after a week of hospital stay (28 th March 2019). He is clinically stable. He is on compression stocking and physiotherapy. He was also counseled on the need of regular clinic check, the need to remove the filter at our center when the DVT resolved.

Discussion
Venous thromboembolism comprised Deep Venous Thrombosis (DVT) and pulmonary embolism (PE) [4]. It is a continuum of a single disease process within the veins that drain blood to the right-sided heart and continue to the pulmonary artery [4]. The 3 case series above had DVT with the 2 nd case diagnosed with pulmonary embolism. Commonly, DVT develops within the deep veins of the lower extremities or pelvic region [3]. But, it can also arise from upper extremities or devices such as a pacemaker, implantable cardioverter defibrillators, cardiac Resynchronization therapy, and long term tunnel dialysis catheters [5]. The most dreaded complication of DVT is pulmonary embolism [4]. Pulmonary embolism is the frequent cause of death among patients with venous thromboembolism [4]. One patient had pulmonary embolism among the 3 patients reported. Death is associated with serious underlying disease in approximately 50% of patients with massive pulmonary embolism [6].

The mainstay of DVT and pulmonary embolism is
Systemic anticoagulation with intravenous heparin followed by oral warfarin or Non-Vitamin K antagonist oral anticoagulants (NOAC). However, as many as 33% of patients will develop a second PE while receiving adequate anticoagulation therapy [7]. The second case reported developed pulmonary embolism while on oral anticoagulation. Also, anticoagulation therapy is associated with bleeding. This limits its use in certain groups of high-risk patients, including patients at high risk for falling, hemorrhagic stroke, metastatic disease, or bleeding diathesis. The concern about the possibility of IVC filter precipitating renal vein thrombosis has prompted many to recommend that vena cava filters be placed in the infrarenal portion of the inferior vena cava [10]. The 3 patients reported had infra-renal IVC filters. Supra-renal IVC filter placement is a valuable technique that helps to prevent pulmonary embolism in the patient that has an indication for IVC filter but contraindication to infra-renal placement.

Realignment technique
In the realignment technique, a loop snare with single access, curved or angled angiographic or guiding catheter allow sufficient redirection of the snare toward the filter apex, prolapse it between filter & IVC wall. The filter is grasped and realigned.
The maneuver allows the filter to be removed with a snare or pulled to a more central orientation for retrieval cone. This is shown in figure 6 below.

Stiff Wire-Displacement Technique
Tilted filter's apex difficult to conventionally engage and displaced away from the caval wall with stiff straight wire between filter apex and caval wall (see figure 8). Retrieval cone advanced into IVC to grasp filter and wire. This technique can be used from a jugular approach for cone-shaped IVC filters or a femoral approach for trapezoidal filters.

Dual-Access Technique
It is a through-and-through "flossing" approach that increases the distraction force on the tilted non embedded or mildly epithelialized filter (see figure 9). Jugular and femoral vascular access are required. Stiff wire introduced from the femoral or jugular approach, directed btw the filter apex and IVC wall, and snared from the alternate approach. Wire traction applied in caudal and cephalic directions simultaneously. The through-and-through wire should be protected by long covering sheaths or catheters to prevent entry or pelvic vein lacerations during this maneuver (i.e. "cheese-slicing"). This approach can release the filter apex from the IVC wall. Snare introduced through the direction of retrieval would remove the repositioned filter.

Balloon-Displacement Technique
This technique involves the filter being shimmied away from IVC with an interposed angioplasty balloon (see figure 11).
Balloon inflated between the apex of filter or embedded struts, removed from the caval wall. The technique very important for severely tilted filters.

Sling Technique
This technique is useful in a single-access "sling" approach filter with embedded apex. Short-radius reverse-curve catheter, positioned below the retrieval zone of filter to direct guide wire backward in "U-turn" fashion. Para-axial snare, placed through the same outer sheath to grasp the guide wire and exteriorize it .Applicable in tilted IVC filters not removed by standard techniques. Nitinol wire, super elastic with kink resistance, recommended for this approach.

Sandwich Technique
Guide wires passed through a guiding catheter along either side of the filter's "nose," through opposing sheaths. Long catheter & sheath advanced into snug contact against the filter, upward or downward force is selectively & repetitively applied to "rock" the filter-free. The technique can be attempted with a single wire, but the use of parallel wires is recommended to better encapsulate the "neck" of the filter ( figure 13). The approach might also minimize filter disassembly during the traction. Retrieval sheath is used to remove the disengaged filter

Advantages of filter removal
IVC retrieval helps to reduce the risk associated with having a permanent IVC filter (a foreign body within the human body). The following complications can be ameliorated by retrieval of the IVC filter.
a. Occlusion of the filter due to thrombus is the most frequent complication of the filters. [12,13,14] The filter related thrombosis is more with permanent filters [13]. The thrombosis was significantly decreased with the temporary filters [14].
b. IVC filters left in-situ for a long time have been found to develop device-related complications such as fracture, device migration, organ penetration, and IVC perforation. IVC perforation is suspected when the filter components extend 3 mm beyond the IVC wall on CT scan [15].

Indications for remover of ivc filters
a. IVC filter is removed as soon as the underlying indication for filter deployment was over [16].
b. For the patients who cannot take anticoagulation temporarily, as the immediate postoperative period, the implanted IVC filter should be removed once the patient becomes eligible to take anticoagulation. 8 c. IVC filter implanted for prophylactic reasons like immobilization, the filter should be removed once the patient is ambulated.
d. Special attention should be paid to prophylactic filters placed in trauma patients, a situation in which the filter can typically be removed within a relatively short time interval as patients begin to ambulate or are transitioned to anticoagulation [17].

Conclusion
IVC filter placement is a valuable technique that helps to prevent pulmonary embolism in a patient with DVT and have contra-indication for anticoagulation or its failure.