Surgery – Instruments – Internal pressure applicator
Patent
1995-05-09
1997-07-22
Weiss, John G.
Surgery
Instruments
Internal pressure applicator
606191, 604104, 604106, A61M 2900
Patent
active
056499531
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to the filtration of clots circulating in the bloodstream. It relates more particularly to an assembly consisting of a filter and a device for inserting it in the vessel.
To prevent the migration of clots originating from the lower veins of the body into the heart and pulmonary artery, and hence to avoid an embolism, it is known to implant filter devices, hereafter called filters, the purpose of which is to obstruct the passage of clots while at the same time allowing the blood to flow through the vessel.
BACKGROUND OF THE INVENTION
There are numerous types of filter in existence. The so-called GREENFIELD filter, which consists of wires preformed into zig-zags and joined together by a cover, is particularly well known. These wires are arranged to form a cone whose tip is the cover, said zig-zags forming the envelope of the cone. The ends of the wires are provided with anchoring hooks by which the filter can grip the inner wall of the vessel.
The placing of such a filter is effected from an insertion sheath inside which the filter is inserted, the elastic wires being kept approximately in alignment with the longitudinal axis of the sheath. After the distal end of the insertion sheath has been positioned at the location where the filter is to be placed in the vessel, said filter is released with the aid of a thrust component which is a rod capable of being actuated from outside the insertion sheath, and which, bearing on the filter, makes it possible to move the latter while at the same time keeping the insertion sheath steady. Once released in the vessel, the elastic wires develop into a cone inside the vessel, the end hooks on the wires gripping the inner wall of the vessel.
Other filters based on the same working principle have been proposed since this GREENFIELD filter, one having a conical general shape with several lugs joined together at their heads, forming an ogival point and diverging towards their other end. This filter is in a single piece formed from a thin sheet of a material of appropriate elasticity. The lugs in question are therefore flat strips of small thickness. Such lugs are tapered at their free end. For positioning inside the vessel, this filter is placed in an insertion tube. A flexible metal guide is first introduced into the vein; then, using this metal guide, a first, relatively thin insertion tube is introduced which is used as a guide tube for the passage of the insertion tube containing the filter.
Thus, as well as the flexible metal guide, the placing of such a filter requires the use of two insertion tubes.
The Applicant has found various disadvantages to be associated with the devices currently in use. On the one hand, the first insertion tube, through which the second insertion tube containing the filter has to travel, must have a relatively large overall diameter because the second insertion tube can have an internal diameter of 3.6 mm. Thus the first insertion tube may possibly have an external diameter of the order of 5 mm. These tubes are made of a flexible plastic material which must nevertheless be sufficiently rigid to be able to advance inside the vessel while at the same time delimiting an interior space capable of accommodating the second insertion tube. Depending on the sinuosity of the vessels, especially in the case of the left femoral vein, the first insertion tube sometimes becomes prohibitively bent, preventing the second insertion tube from traveling through it normally.
The object which the Applicant set out to achieve is to propose a kit, composed of a filter and a device for placing it, which overcomes the observed disadvantages in that it is of simple design and does not require insertion tubes of large diameter.
This object is perfectly achieved by the kit of the invention, which is composed of a filter, a flexible metal guide, a push-rod and an insertion tube. The filter is formed by elastic lugs extending approximately in the shape of a conical corolla extending from a distal head, which has a s
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Bentex Trading S.A.
O Ki Yong
Weiss John G.
LandOfFree
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