Pulmonary Embolus after Vena Cava Filter Placement

Abstract

This report characterizes risk factors in patients who suffer pulmonary embolus (PE) after insertion of vena caval filter (VCF) and formulates an organized diagnostic and therapeutic plan of management. Three hundred eighteen patients were included in a review of patients undergoing insertion of VCF from 1989 to 1995. Ten patients (six men and four women, ages 25-72 years) from this group (3.1%) experienced PE after VCF insertion. Risk factors for deep venous thrombosis were documented in these ten patients. Venacavography was performed after diagnosis of PE. Thrombus length measured from the apex of the filter was used to determine further therapy. Thrombus 5 cm or greater in length was treated with a second VCF (VCF-2). Smaller clots were treated with anticoagulation (AC). All patients treated with AC underwent repeat vena caval study (CT scan or venacavagram) 10 days to 18 months after treatment. PE occurred from 8 days to 5.5 years after original VCF insertion. Five patients suffered PE longer than 6 months (range, 21-66 months; mean, 39 months) after VCF insertion. Venacavagrams demonstrated thrombus in all ten patients with PE. Six patients were treated with VCF-2 and four patients with AC. Dissolution of thrombus was seen on follow-up in all patients given AC. All 10 patients harbored at least two risk factors for deep venous thrombosis. Malignancy was found in only two patients. Five patients were found to have procoagulant states characterized by decreased levels of anti-thrombin III or protein C or S. No postoperative deaths or early recurrent PE occurred. One patient experienced another PE 5 years after treatment with AC when she discontinued warfarin. Contraindications to AC appeared to be self-limited, and all patients were discharged on warfarin. No significant bleeding occurred during early follow-up. Our findings confirm the reliability and low complication rate for VCF. Patients experiencing PE after insertion of VCF mandate an aggressive diagnostic approach that should include venacavography and a search for identifiable risk factors including procoagulant state. Treatment with AC and insertion of a second VCF both give favorable results. All patients appear to benefit from short- or long-term warfarin therapy, and contraindications to AC frequently are self-limited. Therapy based on clot size warrants further study.