[Percutaneous caval filter Dibie-Musset "DM". Results of animal experiments].

Aim: a 7 F percutaneous cava filter was achieved, developed and tested in a goat. Thanks to its double-spiral original form, it is possible to place and remove it atraumaticaly and percutaneously. PRINCIPLES OF THE FILTER: its diameter, larger than the lower vena cava's (LVC) leads to a flattening of the venous lumen whose flow is intersected by the filter turns, thus creating a netting effect.

Case-report: during 28 months, 40 filters were introduced under fluorscopy in 20 goats. Thanks to 16 embolizations, it was possible to test the effectiveness of the filter against small emboli, with simultaneous cavography and pulmonary angiography in 4 cases. 29 filters were removed by jugular and femoral track, from D0 to D14. 12 goats were sacrificed to investigate histologicaly and macroscopicaly the LVC and control the biocompatibility from the 8th to the 385th day. Clinical and radiological supervision lasted more than one year for 3 goats.

Results: the size of the filter (30, 35, 40 mm) is chosen from the LVC diameter measured by cavography. 30 filters were introduced via jugular vein, 10 via femoral vein. These filters were introduced by catheter 7F thanks to an applicator and placed in correct position in the LVC. RELIABILITY OF THE FILTER: easy percutaneous introduction 7F. Once installed, the filters flatten the LVC; this process is automatically confirmed by cavography, and by scanning in 4 cases. EFFECTIVENESS AGAINST EMBOLI: out of 16 cases, 2 partial failures were observed at the beginning of the experiment (one spiral-fitted filter). Its effectiveness was optimized thanks to the addition of a second spiral which allowed the blocking of over-2 mm clots. PERCUTANEOUS REMOVAL: during the initial removals, partial failures were due to the fragility of the filter and the inflexibility of the extracting material. Successive changes of the shape and the alloy of the filter as well as the development of catheters and extracting materials have led to a sufficient reliability to remove (D0 to D14) the filter in security, by percutaneous tract (9 jugular, 9 femoral) before its clamping on the LVC, on the 15th day. INNOCUOUSNESS: both biological supervision and anatomo-pathological investigation have showed the good tolerance of the filter. In local areas, this atraumatic filter does not wound nor perforate the LVC wall. Histologically, a thickening of the intima is observed. The positive results of this experiment led us to start clinical trials of "DM" filter in human beings.