Objective: To assess the effectiveness and safety of non-permanent filter in preventing pulmonary embolism (PE) caused by deep venous thromboembolism (DVT).
Methods: The clinical data of 12 patients who were implanted with non-permanent filter for documented deep venous thromboembolism in Peking Union Medical College Hospital from September 2003 to June 2006 were retrospectively analyzed.
Results: Among these 12 patients, 10 were implanted with temporary filters, and 2 with retrievable filters. All the 12 operations were successful without major complications. In the 10 patients who received temporary filters, filters were smoothly removed after 4 weeks in 9 patients, while one patient was further treated with anticoagulation therapy for 12 weeks because large emboli were entrapped by filter. In the 2 patients who received retrievable filters, filter were smoothly removed 2 weeks later in one patient; however, in another patient, the filter was left inside because large emboli were entrapped by filter. In all the 12 patients, emboli were entrapped in 6 filters (50%), in which the emboli were larger than 2 cm in 2 patients, larger than 1 cm but less than 2 cm in 1 patient, and less than 1 cm in 3 patients. PE scanning was performed in 10 patients before primary implantation, and PE was found in 5 patients. PE scanning was performed in 8 patients 6 months after implantation, and minor PE was found in 4 patients, whose symptoms and affected pulmonary artery were obviously improved. All patients received regular follow-up (ranged from 3 months to 2 years), 1 patient died of malignant tumor 4 months after operation, 1 patient suffered inferior vena cava occlusion due to large emboli entrapped by the temporary filter, and 1 patient experienced the recurrence of symptomatic DVT. Symptoms were improved in all the 5 patients with PE.
Conclusions: Non-permanent filter can safely and effectively protect patients from PE. More standardized criteria for placement and protocols to ensure timely removal should be developed and implemented.