[Clinical experience of the Greenfield filter--especially about tilting and distal migration of the filters].

Since December 1985, we used Greenfield filter in 8 patients to prevent pulmonary embolism. Mean follow-up period was 42 month. Recurrence of pulmonary embolism was suspected in one patient after perfusion lung scan. Another patient died from other reasons. Occlusion of the inferior vena cava was not suspected in any patient clinically. Tilting and distal migration of the filters occurred frequently. 3 filters tilted greater than 5 degrees compared with the position immediately after their placement. 5 filters migrated distally more than half the length of a lumbar vertebra. Although there was no severe complications in our series, we should pay attention especially to the position and angle of the filters, since an extreme tilting position of the filter could be a possible cause of serious complications.