Temporary vascular filter

Details Temporary vascular filter Temporary vascular filter

1999-09-21

2001-12-04

Recla, Henry J. (Department: 3731)

Surgery

Instruments

Internal pressure applicator

Reexamination Certificate

active

06325815

ABSTRACT:

FIELD OF THE INVENTION
The present invention generally relates to filters for body passageways, and has particular utility in connection with temporary vascular filters.
BACKGROUND OF THE INVENTION
Filters can be deployed in channels or vessels in patient's bodies in a variety of medical procedures or in treating certain conditions. For example, rotating burrs are used in removing atheroma from the lumen of patients' blood vessels. These burrs can effectively dislodge the atheroma, but the dislodged material will simply float downstream with the flow of blood through the vessel. Filters can be used to capture such dislodged material before it is allowed to drift too far downstream, possibly occluding blood flow through a more narrow vessel.
Some researchers have proposed various traps or filters for capturing the particulate matter released or created in such procedures. However, most such filters generally have not proven to be exceptionally effective in actual use. These filters tend to be cumbersome to use and accurate deployment is problematic because if they are not properly seated in the vessel they can drift to a more distal site where they are likely to do more harm than good. In addition, these filters are generally capable of only trapping relatively large thrombi and are not effective for removing smaller embolic particles from the blood stream.
The problems with most temporary filters, which are intended to be used only during a particular procedure then retracted with the thrombi trapped therein, are more pronounced. Even if the trap does effectively capture the dislodged material, it has proven to be relatively difficult or complex to retract the trap back into the catheter through which it was delivered without simply dumping the trapped thrombi back into the blood stream, defeating the purpose of the temporary filter device. For this reason, most atherectomy devices and the like tend to aspirate the patient's blood during the procedure to remove the dislodged material entrained therein.
One promising filter design which overcomes many of these difficulties is shown in International Publication No. WO 96/01591 (the publication of PCT International Application No. PCT/US95/08613 ), the teachings of which are incorporated herein by reference. Generally, this reference teaches a trap which can be used to filter particles from blood or other fluid moving through a body vessel. In one illustrated embodiment, this trap includes a basket
270
which can be deployed and retracted through a catheter or the like, making it particularly suitable for use in minimally invasive procedures such as angioplasty or atherectomy procedures. The fact that this trap is optimally carried on a mandrel
260
further enhances its utility as most common angioplasty balloons and atherectomy devices are used in conjunction with such mandrels. While this trap is very useful and shows great promise in many common procedures, it may be possible to better retain the thrombi collected in the filter during retrieval of the filter.
SUMMARY OF THE INVENTION
The present invention provides a method of deploying a medical filter within a channel in a patient's body and devices which are well suited for use in such procedures. In accordance with one method of the invention, a filter and retrieval catheter are provided. This filter has a radially expandable body having proximal and distal ends and which defines an enclosure. The expandable body has a distal length and a proximal length which includes an opening therein. The retrieval catheter has a lumen with a diameter less than the maximum dimension of the body's expanded configuration. This filter is urged along a length of the channel in the patient's body with the filter body in a radially reduced configuration. The body is radially expanded to its expanded configuration such that it substantially fills the lumen of the vessel and the opening in the body is oriented proximally. Body fluid is permitted to enter the enclosure through this proximally oriented opening and is permitted to pass through the distal length of the body. In so doing, the distal length of the body filters from the body fluid particulate material entrained therein (assuming, of course, that there is any such particulate material of an appropriate size). The proximal length of the body is drawn within the lumen of the catheter, thereby effectively closing the proximally oriented opening within the retrieval sheath to retain said particulate material within the enclosure.
Further refinements of this method are envisioned. For example, in one embodiment, the filter has a narrow proximal end which is smaller than the lumen of the catheter. In drawing the proximal length of the filter within the catheter, this narrow proximal end may be introduced into the distal end of the catheter's lumen. The filter may then be retracted until the internal surface of the catheter engages the body of the filter distally of the opening to effectively create a particulate seal therebetween.
As noted above, the present invention also encompasses a device well suited for use in such procedures. In one embodiment, such a device comprises a collapsible filter system including a mandrel and a filter. The mandrel has proximal and distal ends and the filter is carried along the mandrel between these ends. The filter has a radially expandable body having proximal and distal ends of its own. The body is formed of a porous, resilient fabric having pores therein through which a body fluid may pass, but which are small enough to restrict passage of particulate material over a certain, predetermined size entrained in the body fluid. A proximally oriented hole passes through the fabric along a proximal length of the filter's body. This hole is spaced distally of the proximal end of the body and being at least about five times the size of said pores.


REFERENCES:
patent: 4619246 (1986-10-01), Molgaard-Nielsen et al.
patent: 5192286 (1993-03-01), Phan et al.
patent: 5814064 (1998-09-01), Daniel et al.
patent: 6096053 (2000-08-01), Bates
patent: 6214026 (2001-04-01), Lepak et al.

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