N. Nakagawa et al., A RETRIEVABLE NITINOL VENA-CAVA FILTER - EXPERIMENTAL AND INITIAL CLINICAL-RESULTS, Journal of vascular and interventional radiology, 5(3), 1994, pp. 507-512
PURPOSE: The authors describe the properties of a new retrievable niti
nol vena cava filter and report experimental and initial clinical resu
lts. MATERIALS AND METHODS: The filters, made of nitinol monofilament
wire that forms a spiral cone and retrieval wire, were introduced thro
ugh an indwelling 5.5-F transfemoral sheath into the infrarenal portio
n of the inferior vena cava in 10 sheep. In seven animals, four 4 x 30
-mm radiopaque clots were injected below the filter to test its thromb
us-trapping efficacy. Aspiration thrombectomy was then attempted, and
the filter was removed. Follow-up venography was performed 1 week afte
r placement in three other animals. After successful preclinical testi
ng, the filter was implanted and retrieved in two patients. RESULTS: A
ll 10 filters were successfully and easily placed in sheep. All filter
s were thrombus-free at follow-up venography. All clots injected in th
e iliac veins were trapped by the filter and successfully removed by m
eans of aspiration thrombectomy. All 10 filters were retrieved without
difficulty. Temporary filter implantation and retrieval were accompli
shed in two patients for 5 and 7 days. In one patient, infrafilter thr
ombus was aspirated. Perisheath thrombosis occurred in both patients.
One patient subsequently underwent permanent filter placement. CONCLUS
ION: Temporary vena cava filtration is feasible. Potential advantages
include easy placement, surveillance, and retrieval. One current limit
ation is pericatheter thrombosis, which may be eliminated by a less th
rombogenic sheath.