WO1999040957A1

WO1999040957A1 - Method of and apparatus for navigating medical devices in body lumens

Info

Publication number: WO1999040957A1
Application number: PCT/US1998/002835
Authority: WO
Inventors: Walter M. Blume; Jeffrey M. Garibaldi
Original assignee: Stereotaxis, Inc.
Priority date: 1998-02-17
Filing date: 1998-02-17
Publication date: 1999-08-19
Also published as: AU6165298A

Abstract

This invention is a guide wire (22, 102) combined with a catheter (20) or medical device for moving through a body lumen to a desired position in the body with the aid of an applied magnetic field. The guide wire is provided with a magnet (28) on its distal end that can be oriented or oriented and moved by the application of a magnetic field to the magnet. A catheter or other medical device can be advanced over the guide wire. Once the medical device is in its desired position, the magnet can be withdrawn through the lumen of the catheter. Alternatively, a guide wire with a magnet on its distal end can be docked at the distal end of a catheter or medical device and can be oriented, or oriented and moved by the application of a magnetic field.

Description

METHOD OF AND APPARATUS FOR NAVIGATING MEDICAL DEVICES IN BODY LUMENS

FIELD OF THE INVENTION

This invention relates to a method of, and apparatus for, navigating medical devices in body lumens, such as in blood vessels, the trachea, the gastrointestinal tract, or the urinary tract.

BACKGROUND OF THE INVENTION

Many diagnostic and therapeutic medical procedures require navigating a medical device to a particular location through lumens in the body. For example, procedures such as cardiac catheterizations and interventional neuroradiology procedures involve the introduction of medical devices through the arteries; bronchoscopies involve the introduction of medical devices through the trachea; endoscopies and colonoscopies involve the introduction of instruments through the gastrointestinal tract; and urethroscopies involve the introduction of medical devices through the urinary tract . Numerous methods and apparatus have been developed for introducing medical devices in the body. Many of these methods employ guide wires for remotely controlling the orientation of the tip of the medical device as it is advanced in the body lumen. These guide wires typically have a bend in their distal ends, the tip is rotated until the tip is properly oriented, and the wire is then advanced. It is a difficult and tedious process to steer a medical device remotely with a guide wire since the orientation of the guidewire is difficult to contol . Thus, these procedures can be prolonged, which increases the risk to the patient and fatigues the physician.

It has been proposed to guide medical devices in the body with magnets, see Yodh, Pierce, eggel, and Montgomery, A New Magnetic System, for ' Intravascular Navigation', Medical & Biological Engineering, Vol. 6, No. 2, pp. 143-147 (March 1968), incorporated herein by reference. This article proposes a magnetically tipped catheter that is steered within the body by an externally applied magnetic field. However, the magnet in this proposed device is attached to the catheter which can impair the ability to control the magnet. Moreover, there is no provision for removing the magnet and leaving the catheter or other medical device in place. Thus, only one such catheter can be directed to a given position because the magnetic field acting on one magnet will also act on the other magnets in the vicinity.

SUMMARY OF THE INVENTION

The methods and apparatuses of the present invention involve magnetically guiding a medical device through a lumen in the body. Generally, according to the method of this invention, a magnet is provided on the end of a guide wire and an externally applied magnetic field orients the magnet in the body lumen. The magnet can be advanced through the body lumen by manipulating the magnetic field or by pushing the guide wire.

According to a first embodiment of this invention, a catheter may be disposed over a guide wire having a magnet on its distal end. The guide wire and catheter combination is introduced into a body lumen through a natural or surgically formed opening. Once in the body the guide wire and catheter combination is navigated through the body lumen by applying a magnetic field, which acts on the distal end of the guide wire, orienting it. Typically, the guide wire is advanced slightly ahead of the catheter at a branch in the body lumen, and a magnetic field is applied to orient the tip of the guide wire, and the guide wire is advanced in the direction of the tip which is oriented into the selected branch. The guide wire can be advanced by the application of the magnetic field, by pushing at the proximal end, or by both. The catheter is then advanced over the guide wire. This process is repeated until the distal end of the catheter is at its desired location. Once the distal end of the catheter is in the desired position, the magnet can be withdrawn through the lumen of the catheter by pulling on the tether. Treatment, such as drug therapy or embolizing agents, can then be passed through the catheter.

According to a second embodiment of this invention, a guide wire with a magnet on the tip may be docked at the distal end of the lumen inside a catheter or other medical device . The guide wire and catheter combination is introduced into a body lumen through a natural or surgically formed opening. Once in the body lumen, the guide wire and catheter combination is navigated through the body lumen by applying a magnetic field, which acts upon the magnet-tipped guide wire in the catheter, orienting it. The catheter is advanced by pushing the guide wire. Once the distal end of the catheter is in the desired location, the guide wire can be withdrawn through the lumen of the catheter by pulling on the guide wire. Treatment, such as drug therapy or embolizing agents, can then be passed through the catheter.

The methods of the various embodiments of this invention, and the guide wire of the various embodiments of this invention, facilitate quick, easy and accurate positioning of a catheter or other medical device via a body lumen. Once the catheter is properly positioned, it can be used during a diagnostic or therapeutic procedure, either directly or as a passage for other medical devices .

These and other features and advantages will be in part apparent and in part pointed out hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a longitudinal cross-sectional view of a guide wire and catheter combination constructed according to the principles of a first embodiment this invention;

Fig. 2 is a plan view of the guide wire of the first embodiment;

Fig. 3 is an enlarged cross-sectional view of the distal tip of the guide wire;

Fig. 4 is an enlarged cross sectional view of the distal end of the guide wire using a socket to secure the magnet ;

Fig. 5 is an enlarged cross sectional view of the distal end of the guide wire using a collar to secure the magnet .

Fig. 6 is an enlarged cross-sectional view of a first alternate construction of the distal section of the guide wire;

Fig. 7 is an enlarged cross-sectional view of a second alternate construction of the distal section of the guide wire; Fig. 8 is an side elevation view of a third alternate construction of the distal section of the guide wire;

Fig. 8a is a side elevation view of the third alternate construction of the distal section of the guide wire, in a magnetic field;

Fig. 9 is a side elevation view of a fourth alternate construction of the distal section of the guide wire;

Fig. 9a is a side elevation view of the fourth alternate construction of the distal tip of the guide wire, in a magnetic field;

Fig. 10 is a longitudinal cross-sectional view of the guide wire and endoscope combination constructed according to the principles of the first embodiment of this invention;

Fig. 11 is a longitudinal cross-sectional view of a guide wire and catheter combination according a second embodiment of this invention;

Fig. 12 is a longitudinal cross-sectional view of a guide wire and catheter combination with the guide wire partially withdrawn from the lumen of the catheter;

Fig. 13 is a side elevation view of a guide wire and biopsy device according to the principles of the present invention.

Corresponding reference numbers indicate corresponding parts throughout the several views of the drawings .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A guide wire and magnet combination constructed according to the principles of a first embodiment of this invention is indicated generally as 20 in Fig. 1. The guide wire and catheter combination 20 comprises a guide wire 22 and a catheter 24. The guide wire 22 comprises a wire 26, which is preferably made of nitinol, which is 6 highly flexible and resists kinking, although the guide wire could be made of some other suitable material. A magnet 28 is mounted on the distal end 30 of the guide wire 22. This magnet may either be a permanent magnet or a permeable magnetic material. A permanent magnet is easier to orient under the application of a magnetic field, as described below, but a permeable magnetic material is easier to pull under the application of a magnetic field.

In the preferred embodiment, the magnet 28 is made of NdFeB (neodymium-iron-boron) or samarium cobalt and is sized to respond to the magnetic field that will be applied to orient the guide wire 22 in the body lumen and to be retracted through the catheter 24. The magnet 28 is preferably elongate so that it can orient the tip of the guide wire 22 in the presence of an applied magnetic field. Magnets of about 0.4 mm (0.02 inches) to about 0.7 mm (0.03 inches) in diameter, and a length of about 1 mm (0.04 inches) to 1.5 mm (0.06 inches) are sufficiently large for use in navigating a guide wire.

As shown in Fig. 2 and 3, the magnet is preferably a cylindrical body 34 with an axial bore 36 therethrough. The distal end of the guide wire 22 extends through the bore, and is secured with a bead 38 of adhesive on the distal side of the magnet 28. The bead 38 also provides a rounded head on the distal end 30 of the guide wire 22.

As shown in Fig. 4, the magnet 28 could also be attached to the distal end of the guide wire 22 with a socket 39 formed on the end of the guide wire. The socket 39 can be crimped into the distal end of the magnet 28, and/or the magnet can be secured with adhesive. As shown in Fig. 5, the magnet 28 could also be secured by first attaching a collar 41 to the end of the guide wire 22. The magnet 28 can be secured to the collar 41 by adhesive or by fusion. The catheter 24 is preferably of conventional construction, having a proximal end 40, a distal end 42, and a lumen 44 extending therebetween. The catheter 24 can be made of polyurethane tubing, or some other suitable material. The size of the catheter 24 depends upon where in the body it will be introduced, and how it will be used. For example, for use in the blood vessels in the brain, the catheter might have an outside diameter of about 0.7 mm (0.03 inches), an inside diameter of about 0.6 mm (0.02 inches), and a length of about 2m (6.6 feet) .

The guide wire 22 can be introduced into a body lumen, such as a blood vessel, and navigated to its desired location by the controlled application of magnetic fields. The application of a magnetic field allows the operator to steer the distal end of the guide wire 22 by orienting the distal end of the guide wire to the desired direction of travel. The guide wire 22 can be advanced using the magnetic field, or the guide wire can be advanced by pushing the proximal end. As the guide wire advances, the catheter 24 can be advanced over the guide wire 22, until the catheter is in its desired location.

Once the distal end 42 of the catheter 24 has been placed in its desired location, the guide wire 22 can be left in place, or if the magnet 28 is sufficiently small, the guide wire can be withdrawn through the lumen 44 of the catheter and out the proximal end 40. As shown in Fig. 6, a first alternate construction of the guide wire 22' can be provided with a tapering collar 46. The collar 46 facilitates withdrawing the magnet 28 through the distal end 42 of the catheter 24. The collar can be made of a platinum so that the position of the end of the guide wire can be easily located on an x-ray.

The magnetic articulation of the distal end of the guide wire eliminates the need to provide a permanent 8 bend in the guide wire in order to navigate through branches in body lumens. The straight configuration permitted by the guide wires of the present invention permits faster and easier navigation on straight sections and reduces unintentional diversion down branches of the lumen.

As shown in Fig. 7, a second alternate construction of the guide wire 22" has a sheath 48, made of flexible polyurethane tubing, extending over the wire 26. The sheath 48 preferably has the same outside diameter as the magnet 28, to smoothly slide in the lumen 44, and to help prevent the excessive movement of the guide wire 22 within the lumen. The sheath 48 is preferably secured to the proximal end of the magnet 28 with an adhesive, such as SICOMET 40 available from Tracon.

A third alternate construction of the guide wire of the first embodiment is indicated as 50 in Fig. 8. Instead of the single magnet 28 on the distal end of the wire 26, guide wire 50 has a series of spaced magnets 52 on the distal end portion 54 of the wire 56. The magnets 52 are preferably similar in construction to magnet 28, comprising a generally cylindrical body 58, each having an axial bore 60 extending therethrough. The distal portion of the wire 56 extends through the bores 60, and the magnets 52 are secured to the wire 56 in spaced apart relation with adhesive.

The magnets 52 are preferably made from NdFeB, and have a diameter of 2 mm (0.08 inches) and are 4 mm (0.16 inches) long. The magnets 52 are preferably spaced over the distal 5 cm (2 inches) of the guide wire 50, and are spaced 1cm (0.4 inches) on center. Of course some other size magnets and/or different magnet spacing could be used. Moreover the spacing of the magnets does not have to be equal . This alternate construction is particularly useful for an electrophysiology catheter where the magnetic fields could pull or shape the guide wire 50 to the heart wall .

As shown in Fig. 8a, upon the application of a magnetic field, the magnets 52 on the distal end portion 54 of guide wire 50 cause the guide wire to assume a particular shape dictated by the field. Thus by controlling the applied magnetic field, the shape of the distal portion of the guide wire can be controlled, facilitating the navigation through, or shaping to, the body lumen. The guide wire 50 can be pulled by magnet force on the magnets 52, or the distal end can be manually pushed. The pull force could be used to hold the catheter with guide wire to the wall of a body lumen.

A fourth alternative construction of the guide wire of the first embodiment is indicated as 62 in Fig. 9. Instead of the single magnet 28 on the distal end of the wire 26 as in guide wire 22, or multiple magnets 52 on the distal end portion 54 of the wire 56 as in guide wire 50, the distal end portion 64 of guide wire 62 is made from a magnetic material.

The distal end portion 64 is preferably about 0.25 mm (0.01 inches) in diameter, and about 1 cm (0.4 inches) long. The distal end portion is can be made of a permeable magnetic material such as a steel or a magnetic stainless steel wire, or a steel or a magnetic stainless steel braid.

As shown in Fig. 9a, upon the application of a magnetic field, the distal end portion 64 of guide wire 62 assumes a particular orientation dictated by the field. Thus by controlling the applied magnetic field, the orientation or shape of the distal portion 64 of the guide wire can be controlled, facilitating the navigation through the body lumen. The guide wire 62 can be advanced by magnet force on the distal portion 48, or the proximal end can be pushed. The magnetic field can also function to selectively stiffen the distal end of the 10 guide wire, to facilitate navigation through the body lumen. This allows the guide wire to be designed with the minimum amount of stiffness to over come static friction when applying an axial pushing force on at the proximal end. Sufficient stiffness for navigation can be provided by applying a magnetic field to the distal tip.

As showing in Fig. 10, the guide wire 22 can be used to navigate an endoscope 66 through a body lumen, such as a colon. The endoscope 66 has a lumen 68 extending therethrough. A magnetic field is applied to orient the magnet 28 on the distal end of the guide wire with the magnetic field. The endoscope 66 can then be advanced over the guide wire, the lumen 68 sliding over the guide wire. The guide wire 22 is preferably incrementally advanced, and the endoscope is then advanced over the guide wire, until the endoscope reaches its desired location.

A guide wire and catheter combination constructed according to a second embodiment of this invention is indicated generally as 100 in Figs. 11 and 12. The guide wire and catheter combination 100 comprises guide wire 102 and catheter 104. The guide wire 102 comprises a wire 106, preferably made of nitinol, which is highly flexible and resists kinking, although the guide wire could be made of some other suitable material . A magnet 108 is mounted on the distal end of the wire 106. This magnet may either be a permanent magnet or a permeable magnetic material . A permanent magnet is easier to orient under the application of a magnetic field, as described below, but a permeable magnetic material is easier to pull under the application of a magnetic field.

In the preferred embodiment, the magnet 108 is made of NdFeB (neodymium-iron-boron) or samarian cobalt and is sized to respond to the magnetic field that will be applied to move the guide wire 102 through the body lumen. The magnet 108 is preferably elongate so that it 11 can orient the tip of the guide wire 102 in the presence of an applied magnetic field. Magnets of about 0.4 mm (0.02 inches) to about 0.7 mm (0.03 inches) in diameter, and a length of about 1 mm (0.04 inches) to 1.5 mm (0.06 inches) are sufficiently large for use in navigating a guide wire .

As shown in Fig. 12, the magnet is preferably a cylindrical body 110 with an axial bore 112 therethrough. The distal end of the guide wire 102 extends through the bore 112, and is secured with a bead 114 of adhesive on the distal side of the magnet 108. The bead 114 also provides a rounded head on the distal end of the guide wire 102. Of course instead of magnet 108, the guide wire 102 could have a plurality of spaced magnets on the distal end portion similar to guide wire 50, described above, or the distal end portion of the guide wire could be made of a flexible magnetic material similar to guide wire 62.

The catheter 104 is preferably of conventional construction, having a proximal end 116, a distal end 118, and a lumen 120 extending therebetween. The catheter 104 can be made of polyurethane tubing, or some other suitable material. The size of the catheter 104 depends upon where in the body it will be introduced, and how it will be used. For example, for use in the blood vessels in the brain, the catheter might have an outside diameter of about 0.7 mm (0.13 inches), an inside diameter of about 0.6 mm (0.11 inches), and a length of about 2 m (6.5 feet) .

The guide wire 102 is adapted to fit inside the lumen 120, and "dock" with the catheter 104. To facilitate this, the distal end of the lumen 120 has a restriction 122 for engaging the distal end of the guide wire 102. This restriction is preferably formed by a annular flange 124 on ring 126 provided on the distal end of the catheter. The ring 126 can be made of tantalum. 12

The guide wire and catheter combination 100 can be introduced into a body lumen, such as a blood vessel, and navigated to its desired position by the controlled application of magnetic fields. The application of a magnetic field allows the operator to steer the distal end of the guide wire 102 by orienting the distal end of the guide wire to the desired direction of travel. The guide wire 102 can be advanced using the magnetic field, or the guide wire can be advanced by pushing the proximal end. As the guide wire advances, the catheter 104 can be advanced.

Once the distal end 118 of the catheter 104 has been placed in its desired location, the guide wire 102 can be withdrawn through the lumen 120, and out the proximal end 116.

As shown in Fig. 13, the guide wire 102 can be used to navigate a biopsy tool 128 through a body lumen such as a kidney. The biopsy tool 128 has a lumen 130 therein. The distal end of the guide wire 102 is adapted to fit into the lumen 130 and "dock" with the biopsy tool. A magnetic field is applied to orient the magnet 108 inside the lumen 130 of the biopsy tool 128. The biopsy tool 128 can then be advanced, in the desired direction either by pushing the proximal end of the guide wire 102, of pulling the distal end of the guide wire with the magnetic field. When the biopsy tool 128 has been advanced to its desired location, the guide wire 102 can be withdrawn.

The guide wires of either embodiment can be used to deliver catheter or other medical devices to locations within the body accessible via a body lumen. For example the guide wire could be used to navigate a device for retrieval of man made objects stents, or body made objects e.g. stones. The high degree of articulation of the tip provides the control needed to capture and recover such objects. 13

OPERATION

In operation, the guide wire and catheter combination 20 of the first embodiment is introduced through a natural or surgically formed- opening in a body lumen. A magnetic field is applied to orient the distal tip within the vessel. The magnetic field can also be used to advance the distal tip of the guide wire, or the guide wire can be pushed to advance the guide wire in the body lumen. As the guide wire is incrementally advanced the catheter 24 can be advanced over the guide wire. Once the distal end 42 of the catheter is in its desired position, the magnet 28 is removed from the catheter 24 by pulling the tether 26 to withdraw the magnet through the lumen 44 of the catheter.

Because the magnet on the guide wire can be removed from the treatment site, multiple catheters can be directed in the same general area to facilitate a medical procedure with independent control of the catheters .

In operation, the guide wire 102 is inserted into the lumen of the catheter 104 (or other medical device) and the guide wire and catheter combination 100 of the second embodiment is introduced through an opening in a natural or surgically formed opening in a body lumen. A magnetic field is applied to orient the magnet 108 on the proximal end of the guide wire 102, inside the catheter 104. The guide wire and catheter are then advanced, either by applying a magnetic field, or by pushing the distal end of the guide wire. Once the distal end 118 of the catheter is in its desired position, the guide wire 102 is removed from the catheter 104 by pulling the guide wire 102 to withdraw it from the lumen 120 of the catheter.

Once the catheter 24 or 104 is in position it can be used for the administration of drug therapy or to 14 perform a medical procedure or it can be used as a guide to insert medical devices to the area surrounding the distal end of the catheter to perform a medical procedure .

Because the magnet on the guide- wire can be removed from the treatment site, multiple catheters can be directed in the same general area to facilitate a medical procedure withindependent control of the catheters. Of course, the magnet could be left in place within the catheter, if desired.

Claims

15What is claimed:

1. In combination with a medical device having a proximal end, a distal end, and a lumen therebetween, a guide wire having a proximal end, a distal end, and a magnet on the distal -end, the guide wire extending through the lumen of the medical device, with the distal end of the guide wire extending beyond the distal end of the catheter.

2. The combination according to claim 1 wherein the magnet on the distal end of the guide wire is a cylindrical body having an axial bore therethrough, and wherein the distal end of the guide wire extends into the axial bore .

3. The combination according to claim 1 wherein the magnet on the distal end comprises a flexible magnetic material forming the distal end section of the guide wire .

4. The combination according to claim 1 wherein the magnet on the distal end comprises a plurality of magnets on the distal end section of the guide wire in spaced apart relation.

5. A method of navigating a medical device through a body lumen to a desired location within the body, the method comprising: providing a medical device having a lumen therethrough, the lumen having a proximal end and a distal end; inserting a guide wire having proximal end and a magnetic distal tip through the lumen of the device until at least a portion of the magnetic distal tip extends distally beyond the distal end of the lumen in the medical device; inserting the medical device and guide wire into a lumen in the body; navigating the medical device through the lumen in the body by applying a magnetic field to orient the magnetic tip in the desired direction of travel; advancing the guide wire in the direction in which the magnetic tip is 16 oriented; and advancing the medical device over the guide wire .

6. The method according to claim 5 wherein the magnetic tip of the guide wire comprises a magnet mounted on the distal end of the guide -wire.

7. The method according to claim 5 wherein the magnetic tip of the guide wire comprises the distal section of the guide wire being made from a flexible magnetic material.

8. The method according to claim 6 wherein the magnetic tip of the guide wire comprises a plurality of magnets secured on the distal end section of the guide wire in spaced apart relation.

9. The method according to claim 5, wherein the step of navigating the medical device comprises successively incrementally advancing the guide wire and the medical device.

10. The method according to claim 5 wherein the step of advancing the guide wire comprises pulling the guide wire with the magnetic field.

11. The method according to claim 5 wherein the step of advancing the guide wire comprises pushing the proximal end of the guide wire .

12. The method according to claim 5 wherein the step of advancing the guide wire comprises pulling the guide wire with the magnetic field and pushing the proximal end of the guide wire .

13. In combination with a guide wire having a proximal end, a distal end, and a magnetic distal tip, a medical device having proximal end, a distal end, and a lumen extending substantially to the distal end of the device, the guide wire extending into the lumen of the medical device with the magnetic distal tip in the distal end of the lumen in the medical device .

14. The combination according to claim 13 wherein the portion of the guide wire adjacent the distal 17 end is sufficiently flexible to allow the magnetic tip to move in response to an applied magnetic field, but the proximal section of the guide wire is sufficiently stiff to advance the medical device through a lumen in the body .

15. The combination according to claim 14 wherein the magnet on the distal end of the guide wire is a cylindrical body having an axial bore therethrough, and wherein the distal end of the guide wire extends into the axial bore.

16. The combination according to claim 14 wherein the magnet on the distal end comprises a flexible magnetic material forming the distal end section of the guide wire .

17. The combination according to claim 14 wherein the magnet on the distal end comprises a plurality of magnets on the distal end section of _the guide wire in spaced apart relation.

18. The combination according to claim 14 wherein the lumen of the medical device has a stricture therein for engaging the guide wire and retaining the guide wire in the lumen of the medical device.

19. A method of navigating a medical device through a body lumen to a desired location within the body, the method comprising: providing a medical device having a proximal end, a distal end, and a lumen extending to substantially the distal end of the medical device; inserting a guide wire having proximal end and a magnetic distal tip into the lumen until the magnetic tip is substantially adjacent the distal end of the medical device; inserting the medical device and guide wire into a lumen in the body; navigating the medical device through the lumen in the body by applying a magnetic field to orient the magnetic 18 tip inside the lumen of the medical device so that the distal end of the medical device is oriented in the desired direction of travel; advancing the guide wire and medical device in the direction in which the distal end of the medical device is oriented.

20. The method according to claim 19 wherein the magnetic tip of the guide wire comprises a magnet mounted on the distal end of the guide wire.

21. The method according to claim 19 wherein the magnetic tip of the guide wire comprises the distal section of the guide wire being made from a flexible magnetic material .

22. The method according to claim 19 wherein the magnetic tip of the guide wire comprises a plurality of magnets secured on the distal end section of the guide wire in spaced apart relation.

23. The method according to claim 19, wherein the step of navigating the medical device comprises successively orienting and advancing the guide wire and medical device .

24. The method according to claim 19 wherein the step of advancing the guide wire and medical device comprises pulling the guide wire with the magnetic field.

25. The method according to claim 19 wherein the step of advancing the guide wire and medical device comprises pushing the proximal end of the guide wire.

26. The method according to claim 19 wherein the step of advancing the guide wire and medical device comprises pulling the guide wire with the magnetic field and pushing the proximal end of the guide wire .