MODIFIED GUIDEWIRE FOR LEFT VENTRICULAR ACCESS LEAD

Abstract: An improved guide wire (20) for assisting in implantation of a cardiac lead includes three sections (22, 24, 26). The most distal zone (22) is sufficiently floppy to prevent trauma to the vessel walls through which the guide wire (20), and lead are inserted. An intermediate zone (24) is generally stiffer, and has a cross section less than or equal to the cross section of the distal zone (22). The third zone (26) is stiffer yet, and is joined to the intermediate zone by a shoulder (34) to transfer force to the lead.

Description: MODIFIED GUIDEWIRE FOR LEFT VENTRICULAR ACCESS LEAD CROSS REFERENCE TO THE RELATED APPLICATION This patent application is a continuation-in-part of copending application Serial No. 09/097,101, filed June 12, 1998. BACKGROUND OF THE INVENTION I. Field of the invention The invention relates to the implantation and placement of cardiac leads used in combination with cardiac rhythm management devices, e.g., heart pacemakers or defibrillators, to monitor and control the rhythm of the heart. This invention is more particularly directed toward a guidewire configuration adapted to assist in the implantation and placement of cardiac leads having electrodes that are to reside in the distal branches of the coronary venous system, the great cardiac vein, or coronary sinus. II. Discussion of the Prior Art Placement of cardiac leads in the distal branches of the coronary venous system, the great cardiac vein, or the coronary sinus is a difficult task. Often when deploying the lead there comes a point at which the lead cannot be advanced further into the vascular system using standard techniques and equipment. All too often this point is not the optimal position for the lead's electrode either sensing cardiac activity or delivering therapy to the heart. There are several reasons which make proper placement of the lead difficult. These include (1) friction between the vasculature and the lead; (2) partial obstruction of the vasculature; (3) unusually shaped bifurcations in the vasculature; and (4) accumulative friction between lead, guide catheter and guidewire. Prior efforts to resolve such problems included the use of a stiffer guidewire. While stiffer guidewires offer additional support, they may impede advancement due to their relative size with respect to the lumen of the lead. Additionally, when proper placement of the lead is achieved, problems arise during guide catheter extraction. All too often, the act of extracting the guide catheter causes the lead to be dislodged from the implanted position. Standard guidewires and stylets are not suitable for maintaining position while the guide catheter is removed due to insufficient stiffness, lack of appropriate force transmission features, and friction between the guidewire and lumen wall of the coronary vein lead. The present invention is deemed to be an improvement over such prior art guidewires. It is more effective in properly placing the lead. It is also less likely to cause a properly placed lead to become dislodged during extraction of the guide catheter and the guidewire itself. SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a guidewire comprised of at least three zones. Each zone differs from the other two in stiffness and flexibility. Each zone also has geometric characteristics which assist in proper placement of the lead and further assist in preventing dislodgement of the lead as the guide catheter is extracted and as the guidewire itself is extracted. Specifically, the first and most distal zone is intended to be sufficiently floppy to prevent trauma to the surrounding vessel walls when the guidewire is used for deploying a coronary vein lead. This zone includes a spiral wound portion surrounding a thin, solid ribbon core and a spherical tip. The second intermediate zone, is generally stiffer and comprises a solid wire or spiral wound wire having a cross-sectional diameter that does not exceed the cross-sectional diameter of the first zone. The third most proximal zone is of a larger diameter and is stiffer than the first and second zones. The third zone comprises a wire or tube which is manipulated to apply advancement forces during deployment of the lead and counter forces during extraction of the guide catheter. The diametric transition between the second and third zones is abrupt and ideally corresponds to a matching feature in the lead so that this transition is the point where most of the advancement forces and counter forces are transmitted to the lead. Other improvements also exist. For example, the improved guidewire (or portions thereof) can be provided with a hydrophilic coating to produce a highly lubricious surface. The presence of such a surface reduces friction between the lumen wall of the lead and the guidewire thereby reducing the risk that the lead will be dislodged during extraction of the guidewire. Likewise, a locking mechanism can be provided between the lumen of the lead and the guidewire so that forces applied to the guidewire are transmitted to the lead through the locking mechanism. DESCRIPTION OF THE DRAWINGS The foregoing features, objects and advantages of the present invention will become more clear to those skilled in the art from the following detailed description of a preferred embodiment, particularly when considered in conjunction with the accompanying drawings in which like numerals in the several views refer to corresponding parts. Figure 1 is a view showing an intravenous cardiac lead having an electrode positioned in a coronary vein. Figure 2 is a perspective view of a preferred embodiment of the guidewire of the present invention. Figure 3 is a cross-sectional view of a cardiac lead with a guidewire positioned within the lumen of the lead. Figure 4 is a plan view of an alternative embodiment of a guidewire made in accordance with the present invention. Figure 5 is a cross-sectional view of a cardiac lead with a guidewire of the type shown in Figure 4 positioned within the lumen of the lead. DETAILED DESCRIPTION OF THE INVENTION Figure 1 shows a human heart 1 with a coronary lead 10 passing through the superior vena cava 2 , the right atrium 3, and the coronary sinus 4 into the great vein of the heart 5 so that an electrode 12 on the lead 10 is properly positioned in a branch of the coronary vein. When positioned as shown, the electrode 12 can be used to sense the electrical activity of the heart or apply stimulating pulses to the left ventricle 7 without the electrode being positioned within the left ventricular chamber. The present invention is directed toward elongated wires useful in placing the electrode in the vasculature. Such wires are generally referred to as "guidewires". As used herein, the term "guidewire" includes both wires used to position the electrode and wires used to retain the electrode in the proper position as a guide catheter is removed. Figure 2 shows a first preferred embodiment of a guidewire 20 advantageously used to position the coronary lead 10 as shown in Figure 1 and retain the coronary lead in that position as a guide catheter is removed. Guidewire 20 has three zones, a distal zone 22, intermediate zone 24, and a proximal zone 26. The distal zone 22 preferably is 1-1.5 inches long. The distal zone 22 is circular in cross-section and has a cross-sectional diameter of approximately 0.014 inches. The distal zone 22 comprises an internal shapeable ribbon core member 28, a spiral winding 30 and a spherical tip 32. The internal ribbon core member 28, as it extends distally, tapers from about 0.005 inches to about 0.001 inches. This construction is sufficiently floppy such that there is no trauma induced by the guidewire to a surrounding vessel wall. This construction also allows it to be capable of being biased so as to aid in steering through the vasculature. The intermediate zone 24 is generally stiffer than the distal zone 22. The intermediate zone comprises a solid wire having a circular cross-section. The cross- sectional diameter of the wire can vary depending upon the performance needs, but should not exceed the cross- sectional diameter of distal zone 22. The length of intermediate zone 24 can also vary, but preferably will be one to four inches long. The proximal zone 26 is made of a wire or tubing and is the stiffest and longest section of the guidewire 20. The proximal zone 26, being the stiffest and most proximal, is the portion handled and used to apply forces during deployment and guide catheter extraction. Preferably the overall length of the guidewire 20 will be in the range of five feet. The cross-sectional diameter of the proximal zone is larger than the cross-sectional diameter of the distal zone 22 and the intermediate zone 24. For example, if the distal and intermediate zones have a diameter of approximately 0.014 inches, the proximal zone will have a diameter of approximately 0.022 inches. The diametrical transition between the proximal and intermediate zones taper, though abruptly, from 0.022 inches to 0.014 inches. As discussed below, this diametrical transition constitutes a shoulder 34 through which most of the advancement and counter forces are transmitted between the lead 10 and guidewire 20. Figure 3 shows the guidewire 20 of Figure 2 positioned within a lumen 14 of the coronary lead 10. The lumen 14 has a projection 16 which corresponds to the shoulder 34 of the guidewire 20. When the shoulder 34 engages the projection 16, advancement forces applied to the guidewire 20 are transferred to the lead 10 through the shoulder 34 and projection 16 or reduction in lumen diameter. Figures 4 and 5 show a second preferred embodiment of a guidewire 20, specifically referred to as a removal wire. This embodiment is ideally suited for use during removal of a guide catheter. As such, it may be used to replace a standard guidewire after insertion of the lead but before removal of the guide catheter. Again, the guidewire 20 of this embodiment has three zones — a distal zone 22, an intermediate zone 24, and a proximal zone 26. The guidewire 20 shown in Figure 4 is dimensioned in a fashion similar to the guidewire shown in the other three figures. The primary difference between the removal wire shown in Figure 4 and the guidewire shown in the other figures is that the tip 32 is not attached to the core 28 by a solder joint. Also, the tip 32 of this embodiment is not intended to exit the distal end of the lead 10, thus it is not shapeable or steerable in the vasculature. It may be used to lock into the lead 10 and transmit force to the lead tip, but only as used in conjunction with the lead. The tip 32 of this embodiment is not considered atraumatic whereas the tip in the embodiment shown in Figure 2 is designed to be extremely atraumatic. This spiral wound wire is secured to the proximal zone 26 by a solder joint. The direction of the winding will preferably be opposite that of any winding 11 of the lead 10 itself. This allows for better tracking through the central lumen of the lead. The distal zone 22 is a continuation of the spiral winding of the intermediate zone. However, the diameter of the winding is increased to form the distal zone. The distal tip 32 of the coil which forms the intermediate end distal zones is cut square and not attached to a core wire or the like. Thus, as the guide catheter is withdrawn, the square cut of tip 32 seats in the taper of the coil 11 of the lead preventing the lead from withdrawing as the guide catheter is pulled free. Furthermore, as the removal wire is pulled free from the lead, the square, unattached coil tip 32 slightly distends and easily frees itself from the tapered coil section of the lead. This feature allows for easy, predictable removal of the removal wire from the lead, thus preventing loss of lead position upon its withdrawal. In either embodiment, a hydrophilic coating can be applied to create a surface 21 on the guidewire 20 that is highly lubricious. Alternatively, all surfaces of guidewire 20 can be coated with a hydrophilic coating or polytetrafluoroethylene (PTFE) , or some other dry lubricious material, i.e. silicone film. This serves to reduce friction between the guidewire 20 and lead lumen 14 thereby reducing the risk that the lead 10 will be dislodged from its proper position as the guidewire 20 is extracted. What is claimed is:

Claims: CLAIMS 1. For implantation and placement of cardiac leads, a guidewire comprising: a. a floppy distal zone comprising a ribbon core member, a spiral winding, and a spherical tip; b. an intermediate zone coupled to said floppy distal zone, the largest cross-sectional diameter of said intermediate zone being no larger than the largest cross-sectional diameter of said floppy distal zone; and c. a proximal zone having a cross-sectional diameter greater than the largest cross-sectional diameter of said intermediate zone, said proximal zone coupled to said intermediate zone by a tapered shoulder and being stiffer than both the floppy distal zone and the intermediate zone. 2. The guidewire of claim 1 wherein said intermediate zone is stiffer than said floppy distal zone. 3. The guidewire of claim 1 wherein said intermediate zone comprises a solid wire. 4. The guidewire of claim 1 wherein said intermediate zone comprises a spiral wound wire. 5. The guidewire of claim 3 wherein said solid wire has a circular cross-section. 6. The guidewire of claim 1 wherein at least a portion of said guidewire has a lubricious outer surface formed by a hydrophilic coating. 7. The guidewire of claim 6 wherein said lubricious outer surface is a hydrophilic coating. 8. The guidewire of claim 6 wherein said lubricious outer surface is a polytetrafluoroethylene coating. 9. The guidewire of claim 6 wherein said lubricious outer surface is a silicone film coating. 10. For implantation and placement of at least one cardiac electrode, an apparatus comprising (a) a cardiac lead having said electrode coupled thereto and having a lumen defined by a wall and a member projecting inwardly from said wall; (b) a guidewire comprising: (1) a floppy distal zone comprising a ribbon core member, a spiral winding, and a spherical tip; (2) an intermediate zone coupled to said floppy distal zone; and (3) a proximal zone coupled to said intermediate zone by a shoulder dimensional to engage the member projecting inwardly from the lumen wall of the cardiac lead when said guidewire is inserted into said lumen, said proximal zone being stiffer than both the floppy distal zone and the intermediate zone. 11. The guidewire of claim 10 wherein said intermediate zone is stiffer than said floppy distal zone. 12. The guidewire of claim 10 wherein said intermediate zone comprises a solid wire. 13. The guidewire of claim 10 wherein said intermediate zone comprises a spiral wound wire. 14. The guidewire of claim 12 wherein said solid wire has a circular cross-section. 15. The guidewire of claim 10 wherein at least a portion of said guidewire has a lubricious outer surface. 16. The guidewire of claim 15 wherein said lubricious outer surface is a hydrophilic coating. 17. The guidewire of claim 15 wherein said lubricious outer surface is a polytetrafluoroethylene coating. 18. The guidewire of claim 15 wherein said lubricious outer surface is a silicone film coating. 19. The apparatus of claim 1 further comprising means for temporarily locking said guidewire to said lead when said shoulder of said lead is in engagement with said member projecting from said lumen. 20. For implantation and placement of at least one cardiac electrode, an apparatus comprising: (a) a cardiac lead having said electrode coupled thereto and having a lumen defined by a wall; (b) a guidewire comprising: (i) a floppy distal zone comprising a ribbon core member, a spiral winding, and a spherical tip; (ii) an intermediate zone coupled to said floppy distal zone; and (iii) a proximal zone coupled to said intermediate zone, said proximal zone being stiffer than both the floppy distal zone and the intermediate zone. (c) means for transmitting forces between said cardiac lead and said guidewire. 21. The apparatus of claim 20 wherein said means for transmitting forces between said cardiac lead and said guidewire includes a shoulder between the proximal zone and intermediate zone of the guidewire which engages a member projecting from the wall of the lumen of the cardiac lead. 22. For use in implantation of cardiac leads, a guidewire comprising: (a) a floppy distal zone comprising a spiral winding; (b) an intermediate zone coupled to said floppy distal zone, the largest cross-sectional diameter of said intermediate zone being no larger than the largest cross-sectional diameter of said floppy distal zone; and (c) a proximal zone having a cross-sectional diameter greater than the largest cross-sectional diameter of said intermediate zone, said proximal zone coupled to said intermediate zone by a tapered shoulder and being stiffer than both the floppy distal zone and the intermediate zone. 23. The guidewire of claim 22 wherein said intermediate zone comprises a spiral winding. 24. For use in combination with a guide catheter to implant a cardiac lead, said cardiac lead having at least one electrode, a central lumen defined by a wire coil turned in a first direction, a guidewire comprising: (a) a distal zone comprising a spiral winding turned in a second direction and having a square cut tip; (b) an intermediate zone coupled to said distal zone, the largest cross-sectional diameter of said intermediate zone being no longer than the largest cross- sectional diameter of said distal zone; and (c) a proximal zone having a cross-sectional diameter greater than the largest cross-sectional diameter of said intermediate zone, said proximal zone coupled to said intermediate zone by a tapered shoulder and being stiffer than both the distal zone and the intermediate zone. 25. The guidewire of claim 24 wherein said guidewire is insertable into said lumen after placement of the lead so that said tip is engageable with the wire coil which defines said lumen to retain the lead in place during removal of the guide catheter. AMENDED CLAIMS [received by the International Bureau on 24 August 1999 (24.08.99); original claims 1-25 replaced by amended claims 1-21 (4 pages)]. 1. For implantation and placement of cardiac leads, a guidewire comprising: a. a floppy distal zone comprising a spiral winding, a spherical tip covering one end of the ribbon core member and spiral winding; b. an intermediate zone coupled to said floppy distal zone, the largest cross-sectional diameter of said intermediate zone being no larger than the largest cross-sectional diameter of said floppy distal zone, said intermediate zone comprising a solid wire coil; and c. a proximal zone having a cross-sectional diameter greater than the largest cross-sectional diameter of said intermediate zone, said proximal zone coupled to said intermediate zone by a tapered shoulder and being stiffer than both the floppy distal zone and the intermediate zone. 2. The guidewire of claim 1 wherein said intermediate zone is made of a material which makes it stiffer than said floppy distal zone. 3. The guidewire of claim 1 wherein said intermediate zone comprises a solid wire. 4. The guidewire of claim 3 wherein said solid wire has a circular cross-section. 5. The guidewire of claim 1 wherein said lubricious outer surface is a hydrophilic coating. 6. The guidewire of claim 5 wherein said lubricious outer surface comprises a polytetrafluoroethylene coating. 7. The guidewire of claim 5 wherein said lubricious outer surface comprises a silicone film coating. 8. For implantation and placement of at least one cardiac electrode, an apparatus comprising (a) a cardiac lead having said electrode coupled thereto and having a lumen defined by a wall and a member projecting inwardly from said wall; (b) a guidewire comprising: (1) a floppy distal zone comprising, a spiral winding, a spherical tip covering one end of the ribbon core member and the spiral winding; (2) an intermediate zone coupled to said floppy distal zone; and (3) a proximal zone coupled to said intermediate zone by a shoulder dimensional to engage the member projecting inwardly from the lumen wall of the cardiac lead when said guidewire is inserted into said lumen, said proximal zone being stiffer than both the floppy distal zone and the intermediate zone. 9. The guidewire of claim 8 wherein said intermediate zone is made of a material which makes it stiffer than said floppy distal zone. 10. The guidewire of claim 8 wherein said intermediate zone comprises a solid wire. 11. The guidewire of claim 8 wherein said intermediate zone comprises a spiral wound wire. 12. The guidewire of claim 10 wherein said solid wire has a circular cross-section. 13. The guidewire of claim 8 wherein at least a portion of said guidewire has a lubricious outer surface. 14. The guidewire of claim 13 wherein said lubricious outer surface comprises a hydrophilic coating. 15. The guidewire of claim 13 wherein said lubricious outer surface comprises a polytetrafluoroethylene coating. 16. The guidewire of claim 13 wherein said lubricious outer surface comprises a silicone film coating. 17. The apparatus of claim 1 further comprising means for temporarily locking said guidewire to said lead. 18. For implantation and placement of at least one cardiac electrode, an apparatus comprising: (a) a cardiac lead having said electrode coupled thereto and having a lumen defined by a wall; (b) a guidewire comprising: (i) a floppy distal zone comprising a spiral winding surrounding a ribbon core member and a spherical tip covering one end of the ribbon core member and the spiral winding; (ii) an intermediate zone coupled to said floppy distal zone; and (iii) a proximal zone coupled to said intermediate zone, said proximal zone being stiffer than both the floppy distal zone and the intermediate zone. (c) means for transmitting forces between said cardiac lead and said guidewire. 19. The apparatus of claim 18 wherein said means for transmitting forces between said cardiac lead and said guidewire includes a shoulder between the proximal zone and intermediate zone of the guidewire which engages a member projecting from the wall of the lumen of the cardiac lead. 20. For use in combination with a guide catheter to implant a cardiac lead, said cardiac lead having at least one electrode, a central lumen defined by a wire coil turned in a first direction, a guidewire comprising: (a) a distal zone comprising a spiral winding turned in a second direction and having a square cut tip; (b) an intermediate zone coupled to said distal zone, the largest cross-sectional diameter of said intermediate zone being no longer than the largest cross- sectional diameter of said distal zone; and (c) a proximal zone having a cross-sectional diameter greater than the largest cross-sectional diameter of said intermediate zone, said proximal zone coupled to said intermediate zone by a tapered shoulder and being stiffer than both the distal zone and the intermediate zone. 21. The guidewire of claim 24 wherein said guidewire has a diameter small enough so that the guidewire is insertable into said lumen after placement of the lead yet the distal zone has a diameter large enough so that said tip is engageable with the wire coil which defines said lumen to retain the lead in place during removal of the guide catheter.

Inventors: GREENLAND JOHN S, HINDERS MARY N, PETERFESO RANDALL M, TOCKMAN BRUCE A, WESTLUND RANDY W, GREENLAND, JOHN, S., HINDERS, MARY, N., PETERFESO, RANDALL, M., TOCKMAN, BRUCE, A., WESTLUND, RANDY, W.
Applicants: CARDIAC PACEMAKERS INC, CARDIAC PACEMAKERS, INC.
Application year: 1999
Main classification: A61M25
IPC codes: A61M25, A61N1