OBJECTIVETo assess the effectiveness and safety of non-permanent filter in preventing pulmonary embolism (PE) caused by deep venous thromboembolism (DVT).

METHODSThe 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.

RESULTSAmong 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.

CONCLUSIONSNon-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.