Pulmonary Embolism (PE) and Deep Vein Thrombosis (DVT), collectively known as Venous Thromboembolism (VTE), are important causes of disability and death in the United States.  As many as 75% of fatal PEs occur in hospitalized medical patients, and, of the 900,000 estimated cases of VTE that occur each year, more than half occur in the hospital.  VTE results in approximately 300,000 deaths annually and the current morbidity and mortality rates associated with VTE render it the leading cause of in-hospital mortality in the United States.

VTE is associated with considerable long-term morbidity and substantial consumption of hospital resources.  The high prevalence of hospital-acquired VTE is largely due to the underuse of simple, cost-effective prophylactic measures.  The most frequently recommended therapy is prophylactic anticoagulation (with heparin or low-molecular-weight heparin, the standard of care for most patients) followed by long-term treatment with anti-vitamin K drugs (Coumadin).

However, anticoagulation is frequently contraindicated for patients admitted for complex surgery; for critically ill patients with acute bleeding, sepsis, large stroke, or advanced liver disease; and for patients with severe trauma.  These patients pose a particularly difficult therapeutic dilemma because they are at substantial risk of major bleeding if treated with anticoagulants and at risk of fatal PE if not treated.

As alternatives to anticoagulation therapy, Inferior Vena Cava (IVC) filters are considered for patients with proven DVT or PE for whom anticoagulation is contraindicated or therapy has failed.  With the introduction of retrievable filters, i.e., filters that can be placed and then removed when no longer indicated, the role of IVC filters has broadened to include prophylaxis for patients at risk of PE.

Currently, this prophylactic indication is the most common reason for the use of retrievable IVC filters, and it is anticipated that 70% of the filters placed over the next several years will fit into this category.  In spite of the projected growth in the use of retrievable filters, their overall use is very limited, considering the large population at risk.  This underuse is related in part to the difficulty associated with placing them in critically ill patients who cannot be easily transported from intensive care units (ICUs) to the interventional radiology suite, and in part to safety concerns associated with complications such as migration, perforation or occlusion of the vena cava, and a higher risk of postphlebitic syndrome.

Another important problem associated with retrievable filters is the low removal rate: the consensus is that only 25% of filters will actually be removed.  This low removal rate converts retrievable filters into permanent filters in patients for whom the initial indication was for placement of a temporary/retrievable IVC filter.

Related Links

National Heart Lung and Blood Institute:
• What is Deep Vein Thrombosis and Pulmonary Embolism?
• http://www.nhlbi.nih.gov/health/dci/Diseases/Dvt/DVT_WhatIs.html

National Library of Medicine:
• Deep Vein Thrombosis
• http://www.nlm.nih.gov/medlineplus/deepveinthrombosis.html

Mayo Clinic
• Deep Vein Thrombosis
• http://www.mayoclinic.com/health/deep-vein-thrombosis/DS01005

Legs For Life
• National Screening For Vascular Disease
• http://www.legsforlife.org/main.shtml

Centers for Disease Control and Prevention
• Are You at Risk for Deep Vein Thrombosis?
• http://www.cdc.gov/Features/Thrombosis/

Centers for Disease Control and Prevention
• DVT/PE Facts
• http://www.cdc.gov/ncbddd/dvt/facts.html