Retrievable Vena Caval Filter Research Articles

Results of a multicenter study of the retrievable Tulip Vena Cava Filter: early clinical experience.

To evaluate clinically a new, retrievable vena caval filter in a multicenter study. The Tulip filter is a stainless steel half-basket that is suitable for antegrade or retrograde insertion via an 8.5 Fr introducer sheath. The filter can be retrieved via the jugular approach using an 11 Fr coaxial retrieval system. Forty-eight filters were implanted via the femoral approach and 38 via the jugular approach in 83 patients. Follow-up examinations (plain films, colorcoded duplex sonography) were performed up to 3 years after filter insertion (mean 136 days) in 75 patients. Twenty-seven patients were screened by colorcoded duplex sonography for insertion site thrombosis. An appropriate filter position was achieved in all cases. Insertion problems occurred in 3 cases; these were not due to the filter design but to an imperfect prototype insertion mechanism that has now been modified (n = 2) or a manipulation error (n = 1). In 2 of these cases the filters were replaced percutaneously; 1 patient required venotomy for filter removal. No further complications due to filter insertion occurred. Two filters were used as temporary devices and were successfully removed after 6 and 11 days, respectively. There was 1 fatal recurrent pulmonary embolism (PE) and 2 non-fatal PE, 5 complete and 3 partial caval occlusions, and 3 caudal migrations of the filter. Insertion site venous thrombosis was not seen in the 27 patients monitored for this complication. Precise placement of the Tulip filter is feasible by either access route and the device appears mechanically stable. Further observations are needed to confirm that safe filter removal is practical up to 10 days after its insertion.

In vitro evaluation of a new temporary venous filter: The spring filter

To evaluate in vitro the function efficacy of a new variable-sized, temporary venous filter, the Spring filter (SF). The SF was tested in a flow phantom, using flexible, thin-walled polyethylene tubes 12, 14, and 16 mm in diameter to simulate veins. Clots of three sizes were used: 6 x 10 mm, 6 x 20 mm, 9 x 20 mm. Filter deployment was performed, ensuring that its functional diameter after placement was a predetermined multiple of the radius 'r' of the tube: 3.0r, 2.8r, 2.6r, 2.4r. The terminal coil was visually examined for changes in configuration. Clot retention by the filter for a period of 3 min was recorded as a success. The baseline intraluminal pressure and the maximum pressure reached after clot introduction were recorded. The trapping ability was calculated from the results for 10 clots. The effect of the following parameters on filter function were studied: size of embolus, caliber of simulated vein, and functional diameter of filter. The filter configuration was stable. Not a single instance of axial tilting occurred on deployment. Functional diameter was the major determinant of filter function. One hundred percent of clots were trapped irrespective of clot size and tube caliber when the functional diameter was 3.0r. Only 73% (95% confidence interval (CI): 57% - 88%) and 77% (95% CI: 61% - 92%) of small emboli were held up by the filter when the functional diameters were 2.6r and 2.4r, respectively (p = 0.0001). A significant reduction in clot trapping was encountered even with medium clots when the functional diameter was 2.4r (p = 0.02). Against the background of available data on retrievable vena caval filters, the current model of SF warrants further investigation.

Insertion and recovery of a new retrievable vena caval filter. Work in progress.

A new retrievable inferior vena cava (IVC) filter was tested in nine pigs. Insertion was through a 14 French sheath using both the femoral and jugular approaches. All insertions were successful, and there was a 100% postinsertion IVC patency rate (8/8 pigs at one week and 1/1 pig at one month). Addition of an apical hook to the filter design allowed transjugular retrieval of two filters at one week postinsertion. Three of nine filters migrated to the upper IVC. The filter's design allows paraxial blood flow despite trapped thrombus and inhibits filter tilting. In vitro, the filter captured 95% to 100% of 5 X 5 mm clots. If problems with migration can be solved, the new filter may provide effective short- and long-term prophylaxis against pulmonary embolism.

Experience with the Amplatz Retrievable Vena Caval Filter. Work in Progress

The Amplatz retrievable vena caval filter was designed in an attempt to decrease complications associated with the placement of Mobin-Uddin or Kimray-Greenfield filters. The design allows percutaneous retrieval, thus expanding application of the filter to situations requiring temporary prophylaxis against pulmonary embolism. Filters have been placed in 16 patients, nine (56%) for prophylactic purposes. All filters were easily inserted percutaneously. Complications occurred in three patients; these included complete thrombosis of the inferior vena cava below the filter, misplacement of one filter into the pericaval retroperitoneal tissue, and development of thrombus cranial to the filter. With the current introduction system, the possibility of filter misplacement has been essentially eliminated. No patient experienced symptoms suggestive of pulmonary embolism after filter insertion. One filter retrieval has been performed, with no complications.

Experience with the Amplatz retrievable vena caval filter. Work in progress.

The Amplatz retrievable vena caval filter was designed in an attempt to decrease complications associated with the placement of Mobin-Uddin or Kimray-Greenfield filters. The design allows percutaneous retrieval, thus expanding application of the filter to situations requiring temporary prophylaxis against pulmonary embolism. Filters have been placed in 16 patients, nine (56%) for prophylactic purposes. All filters were easily inserted percutaneously. Complications occurred in three patients; these included complete thrombosis of the inferior vena cava below the filter, misplacement of one filter into the pericaval retroperitoneal tissue, and development of thrombus cranial to the filter. With the current introduction system, the possibility of filter misplacement has been essentially eliminated. No patient experienced symptoms suggestive of pulmonary embolism after filter insertion. One filter retrieval has been performed, with no complications.

Retrievable vena caval filter percutaneously introduced.

A vena caval filter than can be introduced percutaneously via the femoral vein is described. We placed these filters in five patients without complications. Experimental work in filter removal one to two weeks after insertion in dogs has been performed.