Abstract
Inferior vena cava (IVC) filters are commonly placed to prevent the development or worsening of pulmonary emboli. They are also inherently thrombogenic. Here we discuss a case of acute IVC filter thrombosis with the unusual presentation of obstructive shock resulting in death. A man, age 70 years, underwent laminectomy for multilevel spinal stenosis. An IVC filter was placed preoperatively for acute calf deep vein thrombosis (DVT). On postoperative day 4 he developed tachycardia, hypotension, and signs of lower extremity arterial insufficiency. No lower extremity swelling was noted. Imaging showed complete IVC occlusion caudal to the IVC filter with extension to bilateral iliofemoral veins. Arterial flow was preserved. Therapeutic heparinization was initiated and urgent percutaneous thrombectomy was performed. However, the patient developed multi-organ failure and died shortly thereafter. This report describes an uncommon etiology of obstructive shock and highlights a potentially life-threatening thrombotic complication associated with IVC filters that clinicians should be vigilant about.
Inferior vena cava (IVC) filters are used to prevent the development or worsening of pulmonary emboli (PE).1 They are commonly placed in patients with acute deep vein thrombosis (DVT) who are unable to be systemically anticoagulated.2 They are also used in patients who have developed recurrent DVT while therapeutically anticoagulated or as prophylaxis in select high-risk patients.2 This includes patients with malignancy, severe trauma to the spinal cord/lower extremities, or free-floating lower extremity thrombus.2 Placement of IVC filters is becoming more frequent due to their ease and speed of placement, but they do have some associated complications. These can be related to the procedure itself, including access site bleeding or thrombosis, filter malposition, migration, or defective deployment, and post procedure complications including filter thrombosis, fracture, or perforation.3
Filters themselves are inherently thrombogenic, as they disturb the laminar nature of venous blood flow and increase venous stasis.3 Higher incidence of DVT has been reported in anticoagulated patients with a filter than in anticoagulated patients without a filter.1 Rates of IVC filter thrombosis can range from 0.6% to 33%, with increasing rates in permanent filters or in filters that have been in situ for longer.1 Permanent filters have higher rates of thrombosis than retrievable filters, although this may indicate the different patient populations who are receiving the different filter types.1 Some filters have been known to harbor greater propensity for thrombus formation due to their physical shape and design, including the Trapease filter,1 which is no longer in use.
Here we present the case of acute IVC filter thrombosis with the unusual presentation of obstructive shock associated with signs of arterial insufficiency. Informed consent was provided by the patient’s next of kin to report this case.
Case Presentation
A man, age 70 years, with a past medical history of lumbar stenosis presented to the emergency room with worsening lower extremity weakness and difficulty with ambulation. Magnetic resonance imaging was obtained and demonstrated new severe stenosis at T1-2 and C3-4, along with severe spinal cord compromise. He was admitted to the hospital, and plans were made to proceed with laminectomy. The morning prior to surgery, he complained of right leg pain. A venous duplex was obtained, which showed acute DVT in the right peroneal and bilateral deep muscle veins. An IVC filter was placed without complication due to inability to therapeutically anticoagulate prior to laminectomy. The patient then proceeded with cervical-thoracic (C3-T2) laminectomy. He was recovering well until late on postoperative day 4, when he developed tachycardia and hypotension. Laboratory testing demonstrated electrolyte abnormalities, including hyperkalemia and metabolic acidosis, and the patient exhibited signs suggestive of lower extremity arterial insufficiency including pallor, poikilothermia, and reduced pulses, although arterial doppler signals were maintained. He was resuscitated with intravenous fluids and vasopressors, transferred to the surgical intensive care unit, and subsequently intubated due to continued hemodynamic instability. A computed tomography angiogram of the chest, abdomen, and pelvis was obtained, which showed complete IVC occlusion caudal to the filter (Figure 1), with extension of thrombus to bilateral iliofemoral veins. Importantly, there was preserved arterial flow and extensive venous collateralization. Bilateral venous duplex confirmed these findings. Therapeutic anticoagulation with a heparin infusion was initiated, which was considered safe as the patient was now postoperative day 5. Hemoglobin during the entire episode remained stable and greater than 10 mg/dL; creatine kinase was checked and was greater than 10,000 U/L, with a mild troponin leak in the 200s. The patient underwent urgent percutaneous mechanical thrombectomy of the IVC, with retrieval of significant amount of thrombus. Stents were placed in bilateral common iliac veins for sluggish flow of contrast on completion venogram. The rhabdomyolysis progressed to myoglobinuric renal failure, and he was initiated on continuous renal replacement therapy. Later that day, the patient developed anisocoria and became nonresponsive. He was started on hypertonic saline for suspected increased intracranial pressure, potentially due to either an epidural hematoma from therapeutic anticoagulation, or as a result of hepatic encephalopathy. He was considered too unstable to undergo brain imaging at that time. The patient deteriorated rapidly, developing multi-system organ failure, including acute liver failure and acute kidney injury with oliguria, severe rhabdomyolysis, lactic acidosis, and thrombocytopenia. His metabolic derangements continued to progress despite resuscitative efforts, and he was transitioned to comfort care by family on post-thrombectomy day 1, postoperative day 6. He expired shortly thereafter.
A computed tomography angiogram (CTA) of the chest, abdomen, and pelvis was showing complete IVC occlusion caudal to the filter with extension of thrombus to bilateral iliofemoral veins.
Discussion
This is a case of acute IVC occlusion that did not present with typical features such as leg swelling or signs of venous insufficiency. This patient’s symptoms were suggestive of obstructive shock due to arterial insufficiency, including hypotension, tachycardia, and pallor with reduced pulses. This presentation has not been well-described in the published literature. There have been case reports of patients presenting in acute shock states, including hypotension, after acute IVC filter occlusion,4 although these are few. These commonly present as phlegmasia cerulea dolens,5-7 with symptoms of venous obstruction such as leg swelling and severe pain. A recent case report described a complete occlusion of a malpositioned IVC filter with symptoms of venous obstruction and subsequent shock, which played a contributing role in the patient’s ultimate demise.4 This is in contrast to the current patient, who did not exhibit symptoms of venous obstruction. The unique presentation of our patient, including shock with reduced peripheral pulses due to IVC filter occlusion, was not identified during our literature search.
Previous study of thrombosis in IVC filters has raised the question of whether the thrombus develops in the filter itself, or whether the filter becomes occluded due to distal thromboemboli.8 No definite consensus has been reached, although both situations likely contribute to IVC filter thrombosis. Interestingly, the published literature has shown that DVT is more common in patients with IVC filters than in patients without.1
Filter thrombosis can cause severe disability including post-thrombotic syndrome, venous claudication or ulceration, PE, or phlegmasia dolens.5 Chronic thrombosis is more common, although still rare, and can present with leg pain, swelling, and claudication.5 Acute thrombosis of IVC filters can result in a myriad of symptoms, such as hematuria or oliguria (from extension of clot to the renal veins), shortness of breath (due to PE), or lower extremity swelling and dilated abdominal veins (due to extension of clot to lower extremity veins).5 Thrombosis in patients with anatomically normal IVCs is often due to a filter; other causes include procoagulopathic conditions such as thrombophilia or malignancy, or extrinsic compression caused by intraabdominal masses or May-Thurner syndrome.5 In those with IVC anomalies, thrombosis is not uncommon.
A review of 1718 patients who had IVC filters placed in the early 2000s demonstrated that filter thrombosis may occur in up to 20% of patients; up to 20% of those with a thrombosed filter were asymptomatic.9 A more recent study reported asymptomatic thrombosis was 10 times more common than symptomatic thrombosis.3 The true level is likely difficult to ascertain, due to lack of imaging or testing in asymptomatic patients. Total filter occlusion may occur in approximately 10% of those with thrombosis.9 Chronic filter thrombosis may be more likely to be asymptomatic due to accessory collateral formation, although symptoms can vary due to the extent of thrombus.8 Possible contributing factors to filter thrombosis include hypercoagulable states (such as pregnancy, malignancy, or heritable conditions), presence of DVT, and specific filter characteristics.8 Mortality due to IVC filter thrombosis is either not described or is so infrequent as to be difficult to quantify; mortality due to IVC filter use has previously been attributed to filter migration or IVC perforation.10
The PREPIC (Prévention du Risque d’Embolic Pulmonaire par Interruption Cave) study showed that symptomatic throm-bosis occurred in 13%, although this was after 8 years post-filter placement.11 There is limited data available on outcomes after IVC filter thrombosis, although studies have explored the rates of filter thrombus propagation and resolution as well as interval development or resolution of PE and DVT.9 Data related to mortality due to complications of IVC filter thrombus has not yet been collated, although a recent study did demonstrate increased 30 day mortality in patients with IVC filters and DVT compared to those treated without a filter.12 The PREPIC11 and PREPIC213 studies are the only two randomized controlled trials to date that have prospectively evaluated the effectiveness of IVC filters.14 The results of the PREPIC study demonstrated that incidence of PE is decreased after using an IVC filter,11 while the PREPIC2 study concluded that IVC filters were not supported in patients who were able to be anticoagulated, as there was increased risk of PE and death with filter use. 13
Conclusion
Clinicians should be aware that acute IVC filter thrombosis can occur days to weeks after filter placement. Although it is not well-described in the literature, a high index of suspicion should be maintained for IVC filter occlusion when encountering a patient with recent filter placement and signs of obstructive shock, as the consequences can be fatal. Concerted efforts should be made to retrieve IVC filters when they are no longer needed to avoid long-term complications. Anticoagulation should be instituted at the earliest safe opportunity.
Footnotes
Disclosures: This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. The authors declare no competing or conflicts of interest.
- Received April 4, 2024.
- Revision received August 14, 2024.
- Accepted August 19, 2024.
References
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