WO1999023950A1

WO1999023950A1 - Method and apparatus for obtaining tissue samples

Info

Publication number: WO1999023950A1
Application number: PCT/US1998/002836
Authority: WO
Inventors: Peter R. Werp; Michael A. Lawson
Original assignee: Stereotaxis, Inc.
Priority date: 1997-11-12
Filing date: 1998-02-17
Publication date: 1999-05-20
Also published as: AU6325698A

Abstract

An apparatus for obtaining a tissue sample from inside the body includes a catheter (20) having a proximal end (22), a distal end (24), and a cylindrical space (38) therebetween, with a tip (32) on the end of the distal end (24) having an opening (34) therein for receiving a tissue sample. A cutting element (42) extends generally across the opening (34). The apparatus is used for obtaining a sample from a tissue mass by inserting a distal end (24) of the catheter (20) into the body and pressing the opening (34) of the catheter (20) against the tissue mass from which the sample is taken to cause a core of the tissue to pass through the opening (34), and into the cylindrical space (38) of the catheter (20). The apparatus is then rotated to cause the cutting element (42) to cut the core of tissue inside the cylindrical space (38) from the tissue mass. The catheter (20) is then withdrawn from the body, and the tissue sample can be removed.

Description

METHOD AND APPARATUS FOR OBTAINING ΗSSUE SAMPLES

FIELD OF THE INVENTION

This invention relates to a method of, and an apparatus for, obtaining tissue samples, and in particular tissue samples from the brain.

BACKGROUND OF THE INVENTION

Various devices have been constructed for harvesting tissue samples. However, there has been a need for a way to reliably harvest a sample of substantially intact cells large enough for diagnostic testing without unduly disturbing the surrounding tissue.

SUMMARY OF THE INVENTION

The present invention relates to a method of, and apparatus for obtaining tissue samples. Generally, the apparatus of the invention comprises a catheter having a proximal end and a distal end, and a lumen extending therebetween. There is preferably at least one cutting element extending generally diametrically across the cross section of the lumen, adjacent the distal end.

In use, the apparatus is applied against the tissue mass from which a sample is to be taken, and pushed into the tissue. The apparatus cores into the tissue mass until a sample of tissue is contained in the distal end of the lumen. Suction can be applied to facilitate drawing the sample into the lumen. The catheter is then rotated about its axis so that the cutting element cuts the sample contained in the lumen from the tissue mass. The catheter is then withdrawn from the tissue. The distal end of the apparatus is preferably sufficiently thin and flexible to pass through a positioning catheter previously inserted into the body to provide access to the tissue of interest.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a top plan view of an apparatus for obtaining tissue samples constructed according to the principles of this inven ion;

Fig. 2a is an enlarged partial longitudinal cross- sectional view of the distal tip of the apparatus taken along the plane of line 2-2 in Fig. 1 ;

Fig. 2b is an enlarged partial longitudinal cross- sectional view of the distal tip of the apparatus taken along the plane of line 2-2 in Fig. 1, showing an alternate construction of the distal tip of the apparatus; Fig. 3 is an enlarged partial cross-sectional view of the apparatus taken along the plane of line 3-3 in Fig. 1;

Fig. 4 is an enlarged partial cross-sectional view of the apparatus taken along the plane of line 4-4 in Fig . 1 ; and

Fig. 5 is an elevation view of the distal end of the device.

Corresponding reference numerals indicate corresponding parts throughout the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An apparatus for obtaining tissue samples constructed according to the principles of this invention is indicated generally as 20 in Fig. 1. The apparatus 20 has a proximal end 22 and a distal end 24, and comprises a proximal section 26 of flexible plastic tubing, and a distal section 28 of a thinner, more flexible plastic tubing 28. As shown in Fig. 3, the section of tubing forming the distal section 28 preferably fits in the distal end of the section of tubing forming the proximal section 26, and the two sections are joined, for example with ultrasonic welding or other suitable means.

There is a luer fitting 30 on the proximal end 22 of the apparatus 20 (Fig. 4). The fitting 30 allows a syringe to be connected to the proximal end 22 of the apparatus to draw air from or inject air into the apparatus 20, thereby creating suction or pressure at the distal end 24. There is a biopsy tip 32 on the distal end 24 of the apparatus 20. As best shown in Figs. 2a and 2b, the tip 32 has an opening 34 in its distal end, surrounded by a beveled cutting edge 36, and a cylindrical space 38 adjacent the opening for receiving and holding a tissue sample. The beveled edge is sharp enough to cut through tissue to core the sample as described below. In this preferred embodiment the bevel is about 22°. The proximal portion 40 of the tip 32 has a reduced diameter to fit in the distal end of the distal section 28, so that the outside of the tip 32 is substantially flush with the outside of the distal section 38.- The tip 32 can be made of 304 stainless steel. In this preferred embodiment, the tip 32 has an outside diameter of about 0.070 inches, and an inside diameter of about 0.050 inches. Thus, in the preferred embodiment the space for receiving the sample is a cylindrical volume 0.050 inches in diameter and extending about 0.120 inches from the distal end of tip 32 to an annular shoulder 41. The preferred dimensions of the tip ( including the sample space) and the tubing might differ depending on the type of tissue being sampled and its location in the body.

While in this preferred embodiment the proximal section 26 and the distal section 28 are made from a flexible tubing, one or both of these sections could be made from rigid tubing, if desired. For example, the entire distal section could be a rigid tube, or the length of the tip 32 could be significantly greater to provide a stiff element better adapted to cut into a mass of tissue to take a sample.

At least one cutting element 42 extends across the opening 34 of the tip 32. There is preferably just one cutting element which in this preferred embodiment is a wire extending generally diametrically across the opening 34. As shown in Fig. 2a, the cutting element is preferably a generally U-shaped section of wire 44, oriented with the bottom of the "U" distal of the top of the "UP In this preferred embodiment, the wire 44 is preferably a 0.004 inches diameter stainless steel wire. Each of the legs of the U-shaped section of wire 44 can be secured to the inside of the tip 32, for example by welding, soldering, or brazing. The bottom of the "U" extends across the opening 34, and is preferably flush with the beveled cutting edge 36, or just slightly distal of the edge (as shown) or just slightly proximal to the edge. In this preferred embodiment the bottom of the "U" of wire 44 extends about 0.040 inches beyond the beveled cutting edge 36.

As shown in Fig. 2b the cutting wire can be a generally U-shaped wire 44 p oriented with the bottom of the "U" distal of the top of the "U" . There are feet 46 and 48 projecting outwardly from the top of the legs of the "U" . The feet 46 and 48 are received in radially extending holes in the wall of the tip 32. The ends of the feet 46 and 48 project through the wall of the tip 32 and are welded to secure the wire 44' in the opening 34. The bottom of the "U" extends across the opening 34, or just slightly distal of the edge (as shown in Fig. 2b) or just slightly proximal to the edge. In this preferred embodiment the bottom of the "U" of the wire 44 extends about 0.040 inches beyond the beveled cutting edge 36.

OPERATION

In operation the distal section 28 of the apparatus 20 is introduced into the body, and the tip 32 is urged against the tissue mass from which the sample is to be taken. The distal section is preferably introduced through a guiding catheter that has been previously placed to provide a direct route to the tissue mass to be sampled. A syringe can be secured to the fitting 30 on the proximal end 22 of the apparatus 20 to evacuate air from the interior of the device to facilitate recovering a tissue sample in the tip 32. The beveled cutting edge 36 cuts in to the tissue against which it is pressed, coring a sample of tissue into the space 38 of the tip 32. At the same time, the cutting element 42 slices through the tissue sample and remains in substantially the same orientation with respect to the tip 32. When the space 38 in the tip 32 is full, and abutting annular shoulder 41, the tip 32 can be rotated (180° for one cutting element, or less if there are multiple cutting element) so that the cutting element 42 can cut the root of the tissue sample core held in the space 38. The apparatus 20 can then be withdrawn from the body, and the tissue sample ejected from tip by operating the syringe to inject air or saline solution into the apparatus to displace the tissue sample from the tip 32.

The apparatus 20 is thus of simple and inexpensive construction. The beveled cutting edge and the cutting wire cooperate to cut and recover a relatively intact sample of tissue with a minimum of disruption to the tissue from which the sample is taken. The ability to apply suction with the syringe facilitates recovery of the tissue, and the ability to apply pressure with the syringe facilitates removal of the sample from the tip.

Claims

What is claimed:

1. An apparatus for obtaining a tissue sample from inside a body, the apparatus comprising:

a catheter having a proximal end, a distal end, and a lumen therebetween;

a tip on the distal end of the catheter having an opening therein for receiving a tissue sample; and

at least one cutting element extending generally across the opening for cutting the tissue sample from the body.

2. The apparatus according to claim 1 wherein there is one cutting element.

3. The apparatus according to claim 2 wherein the cutting element is a wire extending generally diametrically across the opening.

4. The apparatus according to claim 1 further comprising a cutting edge surrounding the opening in the tip for cutting a core from the tissue the tip is pressed against.

5. The apparatus according to claim 4 wherein there is one cutting element.

6. The apparatus according to claim 5 wherein the cutting element is a wire extending generally diametrically across the opening.

7. The apparatus according to claim 4 wherein the cutting element is a generally "U" shaped wire, extending across the opening with the bottom of the "U" oriented distally of the top of the "UP

8. The apparatus according to claim 7 wherein the bottom of the "U" is distal of the cutting edge.

9. The apparatus according to claim 7 wherein the bottom of the "U" is flush with the cutting edge.

10. The apparatus according to claim 7 wherein the bottom of the "U" is proximal of the cutting edge.

11. The apparatus according to claim 4 wherein the cutting edge is generally circular.

12. The apparatus according to claim 1 further comprising a syringe fitting on the proximal end for attaching a syringe.

13. The apparatus according to claim 1 wherein the catheter comprises a proximal section of tubing and a distal section of tubing, and wherein the distal section of tubing has a smaller diameter and is more flexible than the proximal section of tubing.

14. A method of obtaining a tissue sample from a tissue mass, the method comprising:

inserting a distal end of a catheter, having an open end with at least one cutting element extending across the open end, into the body; pressing the open end of the catheter against the tissue mass from which the sample is taken to cause a core of the tissue to pass through the open end and into the lumen of the catheter;

rotating the catheter to cause the at least one cutting element to cut the core of tissue inside the lumen from the tissue mass;

and withdrawing the catheter.

15. The method according to -claim 14 wherein the distal end of the catheter is inserted into the body through a larger diameter guiding catheter extending substantially perpendicular to the tissue mass.

16. The method according to claim 15 wherein the open end of the catheter is surrounded by a cutting edge.

17. The method according to claim 15 further comprising the step of applying suction to the proximal end of the catheter as the distal end of the catheter is urged against the tissue mass to facilitate the passage of the core into the lumen of the catheter.

18. The method according to claim 15 further comprising injecting fluid into the lumen of the catheter after withdrawal of the catheter from the body to eject the tissue sample from the catheter.