16.2 IVC Filters & Foreign-Body Retrieval

IVC Filters & Foreign-Body Retrieval

ARRT Cardiac-Interventional Procedures 2.A.6 covers inferior vena cava (IVC) filter placement and retrieval and intravascular foreign-body retrieval. The same Focus of Questions still applies: anatomy and pathophysiology, indications, contraindications, imaging, access, ultrasound, equipment, complications, and closure. This is not coronary PCI. It is venous filtration and the rescue of metal and plastic that should not be floating in a vessel or chamber.

Quick Answer: Land an IVC filter infrarenal after a cavogram that looks for thrombus, duplicated IVC, and mega-cava. Choose femoral versus jugular access so you do not traverse lower-extremity clot. Retrievable filters can become permanent after tilt, embedment, or strut fracture. Never retrieve through clot without a plan. Foreign bodies — embolized stent, fractured wire, catheter fragment, pacer stylet — are captured with a gooseneck snare, forceps, or a balloon-trap. If a central fragment is stuck, convert to surgery rather than tearing the chamber.

Anatomy, pathophysiology, indications, contraindications

The IVC returns lower-body blood to the right atrium. Deep-vein thrombosis (DVT) that breaks free becomes pulmonary embolism (PE). An IVC filter is a metallic obstacle intended to trap that embolus below the heart and lungs. Standard landing is infrarenal — caudal to the renal-vein inflows — so that if the filter thromboses, the kidneys still drain into a patent cava above the cone. Suprarenal landing is the exception (thrombus to the renal veins, pregnancy with a gravid uterus crowding the infrarenal cava, some duplicated-IVC anatomies), not the default.

Indications (teaching): acute DVT or PE with a contraindication to anticoagulation, or failure of anticoagulation (recurrent PE despite therapy). Filters are not a casual substitute for heparin in a patient who can be anticoagulated.

Contraindications / cautions: uncorrectable coagulopathy that makes even a venous stick unsafe; complete chronic IVC occlusion with no landing zone; infection at the planned access site; a mega-cava larger than the labeled filter diameter (often discussed around 28 mm; some designs go larger, and a mismatch is migration). Do not place a filter into a cava already full of free-floating thrombus without a plan for that clot.

Foreign-body indications are any intravascular object that does not belong: a stent that jumped off the balloon, a wire that fractured, a catheter that sheared at a hub, a pacemaker stylet or lead fragment. Contraindication to a heroic percutaneous pull is an object embedded in a cardiac chamber or central vein when traction would tear the wall — that is a surgical conversation, not a harder yank.

Imaging, access, and ultrasound

Imaging. A cavogram (contrast in the IVC) is not optional paperwork. It shows diameter, the iliac confluence, renal-vein level, filling defects (thrombus), duplicated IVC, and mega-cava. Place the filter in the infrarenal segment you actually measured, not in a memory of “L2–L3.” Fluoroscopy during retrieval shows tilt, hook orientation, strut position relative to the wall, and whether a fragment is already in the heart or pulmonary artery. Continuous fluoro during foreign-body work is how you do not lose a piece off-screen.

Access. Femoral vein and internal jugular (IJ) vein are the two teaching routes. If the patient has femoral or iliac DVT, do not drive a filter delivery system through that clot from the groin — use jugular access so you approach from above. Filter hooks generally point cranially, so retrieval often uses a jugular snare. Placement can be femoral or jugular depending on clot location and device. For arterial foreign bodies (embolized coronary stent now in the iliac), you need arterial access large enough for a sheath that can swallow the object. Venous fragments are a venous sheath problem.

Ultrasound. Linear vascular ultrasound guides the IJ or femoral venous stick, proves compressibility, and keeps you out of the artery. After a large retrieval sheath, ultrasound the groin or neck for hematoma. Echo or intracardiac echocardiography (ICE) may locate a fragment in the right atrium; that is imaging, not a substitute for a snare.

Equipment: filters, snares, and retrieval discipline

Permanent filters (Greenfield-class teaching) are intended to stay. Retrievable (optional) filters are designed with a hook or apex that a snare can capture. Either type can tilt, embed struts in the wall, fracture, penetrate the cava, migrate, or thrombose. A retrievable filter left in too long, or one that has tilted and grown into the wall, is functionally permanent. Document the plan for retrieval when a retrievable device goes in.

Snares. The Amplatz gooseneck (nitinol loop at a right angle to the shaft) is the workhorse for hooks, wire ends, and catheter fragments. Multi-loop snares and baskets add surface area. Endovascular forceps / biopsy forceps grasp when there is no free end to lasso. Balloon-trap: pass a wire through or beside an embolized stent, inflate a balloon distal (or within the stent), and withdraw as a unit into a large sheath so the stent cannot skate further down the artery. Conceptually keep distal protection in mind — a fragment you push becomes a more distal embolus (17.2 expands dedicated filters; here the idea is “do not drive debris into a smaller vessel”).

Never retrieve an IVC filter through clot without a plan. If the cavogram or retrieval venogram shows a large thrombus in the filter or the cava, lysing or extracting that clot first, using a protection strategy, or leaving the filter are the options. Pulling the cone through occlusive thrombus is how you manufacture a massive PE in the lab.

Foreign bodies and when to call surgery

Name the objects: embolized stent, fractured wire, catheter fragment, pacer stylet. Loop a free end with a gooseneck. If there is no free end, create one with a wire, use forceps, or balloon-trap a stent. Maintain continuous fluoroscopy. A larger sheath than the object is required — you cannot pull a 4 mm stent through a 5 Fr hub and call it retrieval.

Convert to surgery when the object is central (right atrium, ventricle, pulmonary artery, caval-atrial junction) and stuck, when traction moves the heart wall or the blood pressure, or when a fractured filter strut has already embolized beyond a safe percutaneous path. Notify the surgeon before the last heroic pull, not after tamponade (6.2) starts.

Complications and closure

Filter complications: insertion-site thrombosis, IVC thrombosis, recurrent PE through or around the filter, tilt, penetration of adjacent structures, strut fracture with fragment embolization, and migration to the heart. Retrieval complications: IVC tear, the PE you created by pulling through clot, and a filter that will not come and must stay. Foreign-body complications: further embolization, dissection, arrhythmia, and tamponade if a stiff fragment exits a chamber.

Closure of a venous stick is usually manual compression and a dressing, sometimes a figure-of-eight or a venous closure aid per lab protocol. Large retrieval sheaths bleed. Anticoagulation status after PE/DVT work is not optional trivia — document it before you pull. Arterial foreign-body sheaths close like any other arterial case (13.3).

Worked case

A retrievable filter was placed from the right IJ because bilateral femoral DVT was present — correct access (do not traverse clot). Six weeks later retrieval is planned. Cavogram shows a large filling defect in the cone. Stop. That is clot in the filter. Snaring now is PE. Plan catheter-directed lysis or thrombectomy, or leave the filter. A second case: a coronary stent strips off the balloon and sits in the external iliac. Upsize the arterial sheath, balloon-trap or snare, and keep fluoro on the fragment. If instead a wire fragment is waving in the right atrium and will not fold into a snare, that is surgical, not a longer fluoro run.

Exam traps

• Infrarenal is the default landing; suprarenal is the exception.
• Cavogram hunts thrombus, duplication, mega-cava — not a courtesy picture.
• Jugular retrieval matches a cranial hook; femoral placement is wrong if you must cross iliac DVT.
• Never retrieve through clot without a plan.
• Central and stuck → surgery, not a bigger snare as a personality test.