WO2000062851A1

WO2000062851A1 - Electrophysiology guidewire apparatus and method of manufacture

Info

Publication number: WO2000062851A1
Application number: PCT/US2000/010982
Authority: WO
Inventors: Harvey W. Collins
Original assignee: C.R. Bard, Inc.
Priority date: 1999-04-20
Filing date: 2000-04-20
Publication date: 2000-10-26

Abstract

An electrophysiology guidewire (20) including an elongated core (22) and a biocompatible coil mechanism (24) disposed helically around the core (22) to define a plurality of windings. The coil mechanism (24) is formed from at least one conductor (A, B, C, D) covered externally with a layer of insulation. The insulation is adapted for selective removal to expose a portion of the at least one conductor (A, B, C, D) to define at least one electrode (#1, #2, #3, #4). The guidewire (20) is manufactured by carrying out the steps of selecting an elongated moldable core (22); coiling at least one insulated conductor (A, B, C, D) in a helical relationship around the core (22) to define a plurality of insulated windings; and removing a portion of the insulation from at least one of the windings to define at least one electrode (#1, #2, #3, #4).

Description

ELECTROPHYSIOLOGY GUIDEWIRE APPARATUS AND METHOD OF MANUFACTURE

Field of the Invention

The invention is directed to catheter guidewires and more particularly an economical electrophysiology guidewire apparatus for maneuvering through a vascular system and a cost-effective method of manufacturing such a guidewire.

Background of the Invention

Electrophysiology (EP) catheters are used for a variety of medical applications to collect data concerning vital organs of interest. These minimally invasive devices are conveniently introduced into a vasculature through an incision and tracked along a guidewire or manually maneuvered into a desired location by a physician. EP catheters are often used to diagnose abnormal heart conditions by sensing electrical signals between respective anode and cathode electrodes at varying locations within the heart. Often called "mapping" the heart, such a technique allows for relatively quick identification of abnormal tissue by sensing abnormal electrical readings caused by such tissue. Other treatments often performed by EP catheters involve ablating abnormal tissue to, for example, destroy undesirable lesions or the like.

A typical example of a conventional EP catheter for internally mapping and ablating cardiac tissue is disclosed in U.S. Patent No. 5,482,037. The catheter generally includes a first spirally wound wire extending the entire axial length of the device and defining a core. A second wire is wound coaxially around the first wire and includes a casing or sheath to house the proximal portion of the catheter. To sense electrical activity within the heart, a plurality of spaced apart electrode rings are disposed annularly around respective proximal and distal portions of the second wire. A medial RF electrode ring is slidably secured around the second wire to selectively ablate abnormal tissue.

Conventional catheters, such as the one described above, often work in tandem with EP guidewires that allow a physician to fluoroscopically monitor the positioning or pacing of the guidewire through the vasculature to the area of interest. EP guidewires. such as those disclosed in U.S. Patent No. 4,922,294, assigned to the assignee of the present invention, and U.S. Patent No. 5,465,732, often include uninsulated multi-filar radioscopic and radiotransparent wires wound spirally around a thin mandrel to effect radioscopic contrasting visible to the physician during imaging. Once proper positioning of the guidewire is attained, a conventional EP catheter typically tracks the guidewire to carry out a specific treatment.

While conventional EP catheters work well for their intended purposes, multi- pole applications often arise, necessitating use of several catheters during a single treatment. Ordinarily, each EP catheter requires a separate incision and a separate introducer system due to the relatively large cross-sectional radius of each catheter. As a result, to support operation of a plurality of catheters, a corresponding number of incisions and introducer systems are generally needed. Not only does this create post-treatment discomfort for the patient, but the complexities involved in manipulating a plurality of catheters from numerous entry sites also creates potential difficulties for the physician.

Another distinct disadvantage inherent in conventional EP catheters involves the manufacture of the devices. Generally, this includes the steps of wrapping the respective coiled wires to define a core, and, in a separate operation, individually measuring and mounting the annular electrodes in spaced apart locations. Installation of the electrodes in this manner not only consumes additional man-hours during fabrication, correspondingly raising manufacturing costs, but often adds undesirable girth to the cross-sectional radius of the device.

Conventional EP guidewires that operate in conjunction with EP catheters typically perform well for fluoroscopic imaging purposes, but like conventional EP catheters, have inherent problems that limit their utility. For example, EP guidewires generally carry no capability for carrying out EP treatments independently of an EP catheter. Consequently, multiple instruments are often used for a single treatment thereby increasing the complexity of the procedure for the physician

Therefore, the need exists for a highly manufacturable EP guidewire having the capability of sharing a single introducer system with a plurality of EP guidewires The need also exists for an EP guidewire having the optional ability to effect EP treatments independently of an EP catheter The guidewire of the present invention satisfies these needs

SUMMARY OF THE INVENTION

The guidewire of the present invention provides a relatively small cross- sectional diameter that permits a plurality of such devices to share a single introducer system thereby minimizing the number of incisions required to perform the treatment. Moreover, the guidewire incorporates a highly manufacturable construction that economically and efficiently establishes the capability for the guidewire of carrying out EP treatments independently of an EP catheter

To realize the advantages above, in one form, the invention comprises an electrophysiology guidewire including an elongated core and a biocompatible coil mechanism The coil mechanism is disposed helically around the core to define a plurality of windings and formed from at least one conductor covered externally with a layer of insulation The insulation is adapted for selective removal to expose a portion of the at least one conductor to define at least one electrode. In another form, the invention compπses a catheter system including a catheter having a formed lumen and a guidewire adapted to shdably engage the catheter lumen The guidewire includes an elongated core and a biocompatible coil mechamsm. The coil mechanism is disposed helically around the core to define a plurality of windings and formed from at least one conductor covered externally with a layer of insulation The insulation is adapted for selective removal to expose a portion of the at least one conductor to define at least one electrode.

In yet another form, the invention compπses a method of fabricating an electrophysiology guidewire having at least one electrode The method includes the steps of selecting an elongated core; coiling at least one insulated conductor in a helical relationship around the core to define a plurality of insulated windings; and removing a portion of the insulation from at least one of the windings to define at least one electrode.

Other features and advantages of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGURE 1 is a side plan view of an electrophysiology guidewire according to one embodiment of the present invention;

FIGURE 2 is an enlarged side view of encircled portion 2 identified in FIGURE 1;

FIGURE 3 is a radial cross-sectional view along line 3-3 of FIGURE 2;

FIGURE 4 is a partial axial cross-sectional view along line 4-4 of FIGURE 3;

FIGURE 5 is a partial perspective view of a mandrel for use in a method according to the present invention; FIGURE 6 is a radial cross-sectional view along line 6-6 of FIGURE 5;

FIGURE 7 is a partial axial view of a partially constructed guidewire according to the method of the present invention;

FIGURE 8 is a partial axial cross-sectional view along line 8-8 of FIGURE 7;

FIGURE 9 is an enlarged view of encircled portion 9 of FIGURE 8; FIGURE 10 is a partial axial cross-sectional view of the present invention according to a second embodiment;

FIGURE 11 is a radial cross-sectional view along line 11-11 of FIGURE 10;

FIGURE 12 is partial axial cross-sectional view along line 12-12 of FIGURE

11; FIGURE 13 is a side plan view of a guidewire including an alternative proximal connection device; and

FIGURE 14 is an axial view along line 14-14 of FIGURE 13. DETAILED DESCRIPTION OF THE INVENTION

Referring to Figures 1 and 2, the electrophysiology (EP) guidewire of the present invention, generally designated 20, incorporates a biocompatible multi-filar coil mechanism 24 wound around an internal core 22 (Figures 3 and 7) and having independently insulated conductors A, B, C, and D to define respective circuits for supporting respective electrodes #1, #2, #3, and #4 (Figure 2) formed in the conductors by selectively removing the insulation surrounding each conductor. By having the capability of forming respective electrodes merely by selectively removing insulation, the guidewire allows a physician to perform EP treatments with a device having a relatively small radial cross-section. Referring now to Figures 1 through 4, the internal core 22 (Figure 3) comprises an elongated formed mandrel having a relatively small radial cross-section and comprising a moldable monomer or polymer material. The moldability of the mandrel conveniently assists in preventing the multi-filar coil mechanism 24 from shifting during winding. The distal end of the mandrel is formed into a smooth mushroom-shaped tip 26 to safely navigate along vascular walls and the like without damaging tissue surfaces. The mandrel may be cold formed into appropriate shapes to facilitate entry into or stability within targeted anatomical sites such as the His Bundle, the right and left atriums and ventricles, and the coronary sinus, artery, and vein.

With reference to Figures 2 through 4, the multi-filar metallic coil mechanism 24 is disposed spirally around the mandrel 22 with the proximal end secured to an electrode tail assembly 40 (Figure 1) and the distal end attached flush to the mandrel tip 26. The distal tips of the respective filars are left unterminated as respective bipolar or unipolar electrode tips. Depending on the application, the number of poles, or filars A, B, C and D may vary with a corresponding effect on the pitch of the respective coil winding. A quadpolar winding is preferred. The respective coil filars are formed of a ductile and electrically conductive compound, such as Medical Grade Steel (MP-35N), or material under the trademark Elgiloy ® available from Elgiloy, Inc., Elgin, Illinois, or high content platinum with enough tensile strength to remain tightly wound into the desired coil shape. The coil mechanism not only provides a unique electrical capability, as will be further described below, but also provides a spring winding construction that offers sufficient stiffness to introduce the guidewire intravenously to the site of interest. Moreover, sufficient flexation is built into the formed coil to prevent undesireable perforations into vascular passage walls and allow intimal contact between the guidewire and the traversed vascular passages. Further referring to Figures 2 through 4, the thin layer of dielectric material 30 disposed around each individual coil filar serves as an important feature for the present invention. The dielectric material, preferably polyvinyl formal resin under the trademark Formvar ® available from Monsanto Co., acts to electrically isolate the filars A, B, C and D from one another. This in effect creates respective individual circuit paths defined by the respective filars. The dielectric material is selectively removable to expose portions of the respective conductive filars and define respective electrodes #1, #2, #3, and #4 (Figure 2) for each respective circuit.

Referring again to Figure 1, the electrode tail assembly 40 comprises a connector apparatus 42 to collect and house the proximal end of the coil mechanism 24 and rout the respective filars A, B, C and D to a plurality of corresponding standard .080 inch jack pins 44. Alternatively, as shown in Figures 13 and 14, the connector apparatus comprises a rotating female receptacle 46 for sealably terminating the respective filars. The tail assembly connects to a switching box or recorder interface (not shown) for use with a computerized diagnostic system (not shown). Referring now to Figures 5 through 9, fabrication of the guidewire 20 is relatively straightforward and begins with the step of selecting the formed mandrel 22, as shown in Figures 5 and 6. Next, the multi-filar coil mechanism 24 is spirally wound around the mandrel, in a progressively axially advancing direction, from the distal end of the mandrel to the proximal end as shown in Figure 7. Generally, the winding step comprises a tension winding technique, wherein a spool of multi-filar wire is wound down the mandrel with the filars in tension to form the coil. Alternatively, a point winding technique may be implemented, wherein the coil is wound from a fixed spool utilizing a diamond-shaped tool, commonly known in the art as a coiling pin, that forms the wire over the mandrel. Coiling pins may be procured from Northern Precise Products Co., Ltd., Japan. Preferably, the mandrel 22 is a moldable mandrel formed of a polymer material. By providing a moldable, polymer mandrel, the filar wires of the coil 24 are substantially prevented from sliding axially along the mandrel after they are wrapped around it. Following the coil winding step, the proximal end of the guidewire is mounted to the tail assembly 40 and the individually isolated filars terminated to the respective contact pins 44. At this time, the respective electrodes #1, #2, #3 and #4 (Figure 2) may be formed in the guidewire by selectively removing portions of the respective filars to expose the conductive material. Because the filars spirally span the entire length of the guidewire, the electrodes may be formed at any location as the particular application requires.

During operation, the guidewire 20 of the present invention is connected to a monitoring system (not shown) that processes and distributes any information provided by the guidewire electrodes to the physician in real-time. The guidewire is then inserted through an introducer system (not shown) that accesses the vasculature through an incision. An example of such an introducer system includes an angiographic catheter having a formed lumen to direct the guidewire to the location of interest. Advancement of the guidewire through the catheter lumen to particular areas may be monitored by tracking the position of one or more of the exposed electrodes.

In circumstances necessitating the use of more than one guidewire, the relatively small radial cross-section of the device allows a plurality of guidewires to be inserted through a single introducer system. This desirably reduces the number of incisions and introducer systems required to adequately perform the treatment.

The EP guidewire of the present invention is conveniently adaptable for a variety of diagnostic procedures, for example, as a bipolar phase device or unipolar phase device. To operate as a bipolar device, respective pairs of filars, such as A, B, and C, D are designated as anode-cathode pairs. The flexibility of the multi-filar wire gives the operator the option of choosing those pairs that provide optimum amplitude readings during use. Moreover, the guidewire may be configured to a unipolar device by utilizing a large indifferent back electrode underneath a patient, and designating one or more of the filars as a sensing electrode.

Referring now to Figures 10 through 12, the guidewire of the present invention according to a second embodiment, generally designated 50, includes features similar to those of the first embodiment and further includes the ability of providing additional electrodes without overaffecting the spring dependent pitch of the multi-filar coil mechanism. With particular emphasis on Figure 10, additional electrodes may be added to the guidewire by winding an overlapping second multi-filar coil 52 coaxially around all but the distal end of a first multi-filar coil 54. By telescopically recessing the outer layer axially inwardly of the first coil, a first set of respective electrodes may be formed in the distally exposed end of the first coil, and a second set of electrodes may be formed anywhere along the length of the second coil. This construction is repeatable with any number of coil layers, subject to the radial limits of the device.

While any additional coil layers may increase the radial cross-section of the guidewire somewhat, the resulting construction provides a predictably suffer multi-pole device. Moreover, by implementing additional electrodes, the number of guidewires required to perform a multi-pole treatment often will be reduced, more than compensating for any additional girth.

Those skilled in the art will appreciate the many benefits and advantages offered by the present invention. A significant feature involves the electrically isolated nature of the respective filars. The filars, in turn, define respective circuit paths for a plurality of selectively formable sensors or electrodes. This construction enables the guidewire to carry out certain EP treatments without the necessity of a corresponding EP catheter having a much larger radial cross-section. The selectively removable insulation also allows for efficient and low cost fabrication of a multi-pole device. Respective poles, or electrodes are then realized by conveniently removing portions of the insulation from the respective filars to expose the conductive material underneath.

Moreover, the relatively small radial cross-section of the guidewire allows a plurality of guidewires to be inserted into the vasculature through a single introducer system. This not only eliminates the need to make multiple incisions, but also reduces the complexity of maneuvering the respective guidewires.

While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.

Claims

WHAT IS CLAIMED IS:

1. An electrophysiology guidewire including: an elongated, moldable core; and a biocompatible coil mechanism disposed helically around said core to define a plurality of windings, said coil mechanism formed from at least one conductor covered externally with a layer of insulation, said insulation adapted for selective removal to expose a portion of said at least one conductor to define at least one electrode.

2. An electrophysiology guidewire according to claim 1 wherein: said core comprises a mandrel.

3. An electrophysiology guidewire according to claim 2 wherein: said moldable material comprises a monomer compound.

4. An electrophysiology guidewire according to claim 2 wherein: said moldable material comprises a polymer compound.

5. An electrophysiology guidewire according to claim 1 wherein: said coil comprises a plurality of axially adjacent and helically wound insulated conductors defining respective electrode circuits.

6. An electrophysiology guidewire according to claim 5 wherein at least one of said conductors is formed with an uninsulated portion to expose said at least one conductor to define an electrode.

7. An electrophysiology guidewire according to claim 1 wherein: said at least one conductor is formed of a material from the group comprising Medical-Grade-Steel and Elgiloy.

8. An electrophysiology guidewire according to claim 1 wherein: said insulation comprises Formvar.

9. An electrophysiology guidewire according to claim 6 and further including: an electrode tail mechanism having a connection device mounted to the proximal end of said guidewire to route said respective conductors to respective connection contacts.

10. An electrophysiology guidewire according to claim 1 wherein: said coil mechanism comprises a single axial layer of multi-filar wire disposed helically around said mandrel.

11. An electrophysiology guidewire according to claim 1 wherein: said coil mechanism comprises a plurality of coaxial layers of multi-filar wire disposed helically around said wire, said plurality of coaxial layers having respective distal portions telescopically recessed to expose a portion of each respective layer.

12. An electrophysiology guidewire including: an elongated mandrel formed of a moldable material; a biocompatible multi-filar coil comprising a plurality of axially adjacent and helically wound insulated conductors defining respective electrode circuits, said coil having at least one of said conductors formed with an uninsulated portion to define an electrode; and an electrode tail mechanism disposed on the proximal end of said coil for collecting and routing said respective conductors to a connector apparatus.

13. A catheter system comprising: a catheter having a formed lumen; and a guidewire adapted to slidably engage said catheter lumen and including an elongated moldable core and a biocompatible coil mechanism disposed helically around said core to define a plurality of windings, said coil mechanism formed from at least one conductor covered externally with a layer of insulation, said insulation adapted for selective removal to expose a portion of said at least one conductor to define at least one electrode.

14. A catheter system according to claim 13 wherein: said core comprises a mandrel.

15. A catheter system according to claim 14 wherein: said moldable material comprises a monomer compound.

16. A catheter system according to claim 14 wherein: said moldable material comprises a polymer compound.

17. A catheter system according to claim 13 wherein: said coil comprises a plurality of axially adjacent and helically wound insulated conductors defining respective electrode circuits, said respective conductors including respective uninsulated portions defining respective electrodes.

18. An electrophysiology guidewire according to claim 12 wherein: said at least one conductor is formed of a material from the group comprising Medical-Grade-Steel and Elgiloy.

19. An electrophysiology guidewire according to claim 12 wherein: said insulation comprises Formvar.

20. An electrophysiology guidewire according to claim 17 and further including: an electrode tail mechanism having a connection device mounted to the proximal end of said guidewire to route said respective conductors to respective connection contacts.

21. An electrophysiology guidewire according to claim 12 wherein: said coil mechanism comprises a single axial layer of multi-filar wire disposed helically around said mandrel.

22. An electrophysiology guidewire according to claim 12 wherein: said coil mechanism comprises a plurality of coaxial layers of multi-filar wire disposed helically around said wire, said plurality of coaxial layers having respective distal portions telescopically recessed to expose a portion of each respective layer.

23. A method of fabricating an electrophysiology guidewire having at least one electrode, said method including the steps of: selecting an elongated moldable core; coiling at least one insulated conductor in a helical relationship around said core to define a plurality of insulated windings; and removing a portion of said insulation from at least one of said windings to define at least one electrode.

24. A method according to claim 23 wherein said step of coiling comprises the step of: winding said at least one conductor along said core with said conductor in tension to establish a tensile winding.

25. A method according to claim 23 wherein said step of coiling comprises the step of: winding said at least one conductor along said core with a coiling pin to establish a point winding.