Catheter guiding system and methods
A steerable guide catheter includes a tip ring at a distal end and one or more pullwires configured to engage with the tip ring when put in tension, the pullwire(s) thereby subjecting the steerable guide catheter to a curving or turning force. The tip ring includes a saddle and one or more pullwire channels allowing the pullwire to be looped over the saddle such that when the pullwire is placed under tension, it abuts against the saddle of the tip ring. Some embodiments include additional catheters axially aligned within or outside of the steerable guide catheter, and include a keying feature aligning the rotation of the multiple catheters. The keys of the keying feature can be formed of a polyamide with a glass microsphere filler, and can be thermally welded to the catheter.
1. A guidance system for accessing a target area within a body, the guidance system comprising: a guidable catheter having a proximal end and a distal end; a tip ring attached to the distal end of the guidable catheter, the tip ring having a distal surface with a first indentation in the distal surface, a first saddle formed within the first indentation and having an inclined surface extending distally to an apex of the saddle that is equal or proximal to the distal surface having the first indentation, a first pullwire channel extends proximally from an opening formed in the inclined surface; and a first pullwire extending to the first saddle, through the opening, over the apex of the saddle, and then extending proximally through a second pullwire channel and from the first saddle, the first pullwire being configured to engage with the first saddle of the tip ring upon application of tension to the first pullwire, the first pullwire thereby subjecting the guidable catheter to a first curving force upon application of tension to the first pullwire; further comprising a second pullwire and a third pullwire extending to the tip ring and configured to engage with a second saddle and a third saddle formed in the tip ring, respectively, the second saddle and the third saddle being formed as raised surfaces within second and third indentations in the distal surface.
2. The guidance system of claim 1 , wherein the tip ring includes a proximal surface.
3. The guidance system of claim 2 , wherein the second saddle and the third saddle is disposed separately from the first saddle such that application of tension to the second pullwire subjects the guiding catheter to a second curving force and application of tension to the third pullwire subjects the guiding catheter to a third curving force.
4. The guidance system of claim 3 , wherein the first, second, and third saddles are disposed on the tip ring at locations that are substantially 90 degrees apart from at least one other saddle.
5. The guidance system of claim 2 , wherein the tip ring includes the first pullwire channel extending through the tip ring from the proximal surface to the first indentation, and the second pullwire channel extending through the tip ring from the proximal surface to the first indentation, the first saddle being positioned at least partially between the first and second pullwire channels such that the first pullwire is passed through the first pullwire channel and over the first saddle before passing through the second pullwire channel.
6. The guidance system of claim 5 , wherein the first saddle has a curved surface such that the first saddle supports the first pullwire in a curved orientation when the first pullwire is engaged with the first saddle.
7. The guidance system of claim 6 , wherein the first indentation is configured in size and shape such that the first pullwire does not extend beyond the distal surface of the tip ring when the first pullwire is engaged with the first saddle.
8. The guidance system of claim 1 , further comprising an inner catheter positioned at least partially within a lumen of the guidable catheter and being axially translatable within the guidable catheter.
9. The guidance system of claim 8 , further comprising a keying feature configured to prevent rotation of the inner catheter relative to an outer catheter, the keying feature including a key joined to the inner catheter or outer catheter and a corresponding keyway disposed opposite the key and configured to receive the key, the key being formed at least partially from a plastic and being integrally joined to the inner catheter or outer catheter.
10. The guidance system of claim 9 , wherein the key has a hygroscopicity such that moisture absorption of the key in physiological conditions is 1 percent or less by weight.
11. The guidance system of claim 9 , wherein the key is formed at least partially from a polyamide, polyether, or a copolymer of ether and amide units.
12. The guidance system of claim 11 , wherein the key is formed at least partially from nylon-12.
13. The guidance system of claim 11 , wherein the key is formed from a polyamide that includes a filler material of glass microstructures.
14. The guidance system of claim 13 , wherein the glass microstructures are glass microspheres.
15. The guidance system of claim 14 , wherein the glass microspheres are included in the key in an amount of about 10 percent to about 40 percent by weight.
16. The guidance system of claim 14 , wherein the glass microspheres have a diameter within a range of about 5 microns to about 15 microns.
17. The guidance system of claim the delivery system of claim 14 , wherein the glass microspheres have a diameter within a range of about 8 microns to about 10 microns.
18. A guidance system for accessing a target area within a body, the guidance system comprising: a catheter having a lumen therethrough; a tip ring attached to a distal end of the catheter to form a guidable catheter, the tip ring having a proximal surface, a distal surface, a first indentation extending proximally from the distal surface, a first saddle formed as a raised surface within the first indentation, with inclined surfaces of the first saddle extending from the first indentation to an apex of the first saddle that is equal or proximal to the distal surface having the first indentation, a first and second pullwire channel extending proximally from the inclined surfaces; and a first pullwire that extends through the first pullwire channel to exit from an opening on one of the inclined surfaces of the first saddle, over the apex of the first saddle, and extends proximally through an opening of the second pullwire channel formed in the other of the inclined surfaces and through the second pullwire channel, the first pullwire being configured to engage with the first saddle of the tip ring upon application of tension to the first pullwire, the first pullwire thereby subjecting the guidable catheter to a first curving force; further comprising a second pullwire and a third pullwire extending to the tip ring and configured to engage with a second saddle and a third saddle formed in the tip ring, respectively, the second saddle and the third saddle being formed as raised surfaces within second and third indentations in the distal surface.
19. A guidance system for accessing a target area within a body, the guidance system comprising: a guidable catheter having a proximal end and a distal end; a tip ring attached to the distal end of the guidable catheter, the tip ring having a distal surface with a first indentation in the distal surface, a first saddle formed within the first indentation and comprising a pair of inclined surfaces extending to an apex of the saddle that is equal or proximal to the distal surface having the first indentation, the pair of inclined surfaces extending from a base of the first indentation an indentation formed in the tip ring to the apex, with openings formed in the inclined surfaces; and a first pullwire extending to the first saddle, exiting a first opening of the openings, looping around the apex of the first saddle, and extending proximally through a second opening of the openings, the first pullwire being configured to engage with the first saddle of the tip ring upon application of tension to the first pullwire, the first pullwire thereby subjecting the guidable catheter to a first curving force upon application of tension to the first pullwire; further comprising a second pullwire and a third pullwire extending to the tip ring and configured to engage with a second saddle and a third saddle formed in the tip ring, respectively, the second saddle and the third saddle being formed as raised surfaces within second and third indentations in the distal surface.