Patent Application
20110301684
This invention is in the field of means and methods for the treatment of stenoses that occur in human blood vessels by the implantation of intravascular stents.
At the present time in the history of stenting, stenoses of the arterial system are typically diagnosed with the use of angiography in which contrast medium is injected into the suspected vascular region and x-ray imaging is used to determine if there is a stenosis. To accomplish coronary angiography, the interventional cardiologist typically advances an angiographic catheter through an introducer sheath at the patient's groin with the distal end of the angiographic catheter being placed at the ostium of the coronary artery in the vascular region that is being examined. If a clinically significant stenosis is revealed by angiography, and if stenting is to be used as the means to dilate that stenosis, the angiographic catheter and (often) the introducer sheath are replaced with a new introducer sheath and guiding catheter both of which typically have a larger diameter as compared to the angiographic catheter and its introducer sheath. Typically, the catheter used for angiography will be sized from 4 FR to 6 FR (˜1.3 to 2 0 mm) in diameter and for stenting, the minimum diameter guiding catheter would typically be 6 FR (2 mm). The FR (French) diameter of a catheter expressed in millimeters is equal to the FR size divided by three. As an example, a 6 FR guiding catheter would have an outside diameter of 6/3=2 mm. A 6 FR introducer sheath used with a 6 FR guiding catheter would have to have an inside diameter that would allow the 6 FR guiding catheter to pass through which requires that the sheath have an even larger outside diameter which is typically 8 FR (˜2.7 mm). For coronary stenting, a 7 FR guiding catheter is often used and the associated introducer sheath would have a 9 FR (3 mm) outside diameter. With these sheaths with 2.7 mm to 3 mm diameters, it is not unusual to have bleeding at the groin after the introducer sheath is removed. That type of bleeding is potentially dangerous for the patient and occasionally requires a blood transfusion, vascular surgery or both to repair vascular damage. Such additional treatments are both expensive, time consuming and uncomfortable for the patient. In addition, major bleeding at the sheath insertion site is an independent predictor of late mortality after coronary artery stenting.
U.S. Pat. Nos. 5,180,376, 5,324,262 and 5,423,774 describe a non-kinking introducer sheath that includes a flat wire helix in the plastic of the sheath tube. The designs of these patents are generally greater in wall thickness than existing sheaths and do not envision the combination of an ultra-thin wall sheath with a combination angiography & guiding catheter.
U.S. Pat. No. 5,389,090 describes a unique guiding catheter that can be used to reduce the size of the opening made in the femoral artery when doing angiography and/or stenting. By using a dilator to place the guiding catheter through the femoral artery at the groin, the introducer sheath could possibly be eliminated thereby reducing by an additional two French sizes the size of the opening that is made in the femoral artery at the groin. Any reduction in the size of the opening in the groin is highly advantageous for reducing bleeding at that site in the femoral artery after the introducer sheath (if used) and the guiding catheter are removed. However, most interventional cardiologists prefer to have an introducer sheath left in the patient during the procedure to allow changes in catheter shapes, as well as when the procedure is over to inject medications and to allow quick access back into the artery. Therefore, a catheter system that could reduce the size of the opening in the groin while also having an introducer sheath for the angiographic catheter to slide through would be advantageous for the stenting or angioplasty of any coronary (or other) artery.
When angiography is performed, there is a need for stenting or angioplasty in only about one third of such procedures. When stenting following angiography is not needed, it is still advantageous for the patient to have as small an opening made at the groin (or in the arm for radial artery stenting) as is possible. Therefore, the Intro-Angio-Guide catheter as described herein can be a very valuable tool for the interventional cardiologist whether or not angiography is or is not followed by stenting. This is true for doing angiography with or without stenting for all regions of a human body including peripheral arteries, bypass grafts and arteries of the heart, brain, kidneys, etc. The Intro-Angio-Guide catheter as described herein is ideally suited to be used with the stent-on-a-wire (S-O-A-W) stent delivery system as described in U.S. Pat. No. 6,375,660, or any other low profile balloon angioplasty or stent delivery system.
The present invention is called an Intro-Angio-Guide because it combines in one device; (1) an introducer sheath; (2) an angiographic catheter; and (3) a guiding catheter for use with a balloon angioplasty catheter, or a low profile stent delivery system such as the stent-on-a-wire (S-O-A-W) stent delivery system. Another way of looking at this device is that it combines, (1) an introducer sheath: and (2) an Angio-Guide catheter which can serve as an angiographic catheter or as a guiding catheter for a low profile stent delivery system, and (3) a sheathing catheter that is soft and flexible enough in its distal portion to allow it to be tracked over the shaft of a stent delivery system, such as S-O-A-W, to allow backup and low volume contrast injection in the more distal part of the coronary artery during stent placement. Thus, a single catheter (the Angio-Guide catheter) can serve as both an angiographic catheter to perform angiography and as a guiding catheter when using the S-O-A-W or another small diameter delivery system for the stenting of a blood vessel. The advantage of the present invention compared to existing devices is that the introducer sheath fits snugly over the cylindrical shaft of the Angio-Guide catheter and it has a wall thickness of less than 5 mils (a mil is 1/1,000 of an inch). It is practical to have a wall thickness for the introducer sheath of the Intro-Angio-Guide catheter that is only 2 to 3 mils. Because the thin-walled introducer sheath is inserted through the groin when wrapped around the Angio-Guide catheter, it does not buckle as it would, at that very thin wall thickness, if it weren't wrapped around a comparatively strong cylinder, namely, the shaft of the Angio-Guide catheter.
For coronary angiography, the following procedure is used after a guide wire has been placed through the groin and advanced through the femoral artery:
Because the introducer sheath fits snugly over the shaft of the Angio-Guide catheter with a clearance of only 1 to 2 mils, and because it has such a thin wall, the outside diameter of the Intro-Angio-Guide catheter will only be about 0.6 FR larger than the outside diameter of the Angio-Guide catheter. This compares with a diameter increase of about 2.0 FR when a conventional introducer sheath is used. This smaller outer diameter for the Intro-Angio-Guide system will tend to reduce the risk of bleeding at the groin that can be a serious problem for patients undergoing angiography or stenting. To facilitate the thinnest wall introducer sheath component with the maximum wall strength, a flat wire helix or braid may be included within the plastic of the present invention Intro-Angio-Guide introducer sheath. It is also envisioned that the distal end of the sheath, the distal end of the Angio-Guide catheter and the distal end of the straightening dilator used with the Angio-Guide catheter would have radiopaque markers to facilitate delivery under fluoroscopy. It is also envisioned that the distal 10-20 cm of the Angio-Guide will be relatively soft and flexible to allow it to be tracked down a coronary artery over the shaft of a balloon angioplasty catheter or a stent delivery system, and thus act as a distal support catheter, providing for superb “backup” to allow better steering and lesion crossing of the stent system as well as imaging of distal target lesions using a minimum of contrast.
The inventive means and method described herein is particularly valuable for the new type of stent delivery system (the S-O-A-W system) that is described in U.S. Pat. No. 6,375,660. The very small stent delivery system outside diameter made possible by the S-O-A-W system can allow, for the first time, the use of the same diameter introducer sheath and guiding catheter both for angiography and for stenting. Specifically, a 4 FR, 4.5 FR or 5 FR Intro-Angio-Guide catheter can be used to first perform angiography. If stenting of a stenosis is then required, the S-O-A-W stent delivery system can accomplish the stenting procedure using the same Intro-Angio-Guide system as was used for angiography. If a conventional stent delivery catheter is used to deliver a conventional stent, this would often require an introducer sheath and a guiding catheter with a larger diameter as compared to the Intro-Angio-Guide. It is anticipated that a unique Intro-Angio-Guide catheter whose size is 4.5±0.3 FR would be ideal for first performing angiography and then stenting any stenosis that is found in any artery of the body.
Thus one object of the present invention is to use the Intro-Angio-Guide catheter for angiography, thus minimizing the opening through the patient's skin.
Another object of the present invention is to use the Intro-Angio-Guide catheter to first perform angiography and then to perform angioplasty and/or stenting using the S-O-A-W stent delivery system, or some other very low profile stent delivery system, thereby providing the smallest possible opening in the skin at the patient's groin.
Another object of this invention is to use an Intro-Angio-Guide system whose outside diameter of its introducer sheath is less than or equal to 5.5 FR to accomplish both angiography and stenting.
Still another object of this invention is to reduce procedure time and lower costs for an interventional procedure by using the same introducer sheath and guiding catheter for both angiography and stenting.
Yet another object of this invention is to construct the introducer sheath component of the Intro-Angio-Guide system using very thin walled tubing that includes either round or flat metal wires that are either braided or helically wrapped within the plastic of the sheath tubing.
Still another object of this invention is to reduce procedure time and lower costs for stenting a blood vessel of the human body by using the Intro-Angio-Guide system with the S-O-A-W system thereby eliminating the need for going to a larger diameter introducer sheath and guiding catheter after angiography reveals the need for stenting, as well as essentially eliminating the need for costly vascular closure devices.
Still another object of this invention to allow the distal portion of the Angio-Guide to be tracked down a coronary artery over the shaft of a balloon angioplasty catheter or a stent delivery system, and thus act as a distal support catheter, to provide “backup” to allow better steering and lesion crossing of the stent system as well as imaging of distal target lesions using a minimum amount of contrast medium.
These and other objects and advantages of this invention will become obvious to a person of ordinary skill in this art upon reading the detailed description of this invention including the associated drawings as presented herein.
The design of
The present invention is designed to accomplish the goal of having the smallest possible opening in the groin while at the same time, having an introducer sheath that can remain in place at the end of the procedure and through which the catheter to access the coronary circulation can slide back and forth as necessary for an angiography or stenting procedure without having a long catheter rubbing the opening in the groin. The invention to accomplish this goal is illustrated in
To optimize the structural rigidity of the introducer sheath 40, it would be advantageous for the shaft 41 to include some metal wire structure placed within a plastic material such as PTFE or Nylon or any similar plastic material. The metal wire structure (not shown) could be in the form of a wire mesh or a thin-walled, flat wire helix. Stainless steel would be an optimum metal for the wire structure within the shaft 41. The shaft 31 and distal shaft 33 of the Angio-Guide 100 may also include a metal wire structure as is often the case for guiding catheters.
After the Intro-Angio-Guide 100′ is in place with the distal end 34 of the shaft 31 with radiopaque marker 35 firmly situated through the ostium of a coronary artery, angiography is performed by injecting contrast medium into the heart's arterial system. If no stenosis that warrants revascularization is detected, the angiography procedure is completed and the Intro-Angio-Guide 100′ can be removed from the patient's body in either one or two steps. If there is no reason to leave a sheath for medication or later arterial access, the entire system can be removed. Otherwise, the Angio-Guide catheter 30 is removed and the sheath 40 would remain for a period of time before it too is removed.
Because the outside diameter of the thin-walled introducer sheath 40 is only about 5.1 FR that would be a smaller outside diameter as compared to any other introducer sheath used for angiography that is on the market today. The smallest possible opening in the groin is very important to prevent bleeding at the groin after the introducer sheath is removed.
If the angiography detects a “significant” stenosis in the artery, it is typical in medical practice today to place a stent into that stenosis in order to improve blood flow to the myocardium. If that is the case, then the S-O-A-W stent delivery system as described in U.S. Pat. No. 6,375,660, or other low profile stent delivery system can be used with the Intro-Angio-Guide system 100′ to deliver a stent (not shown) into that stenosis. Because of the very small outside diameter of the S-O-A-W stenting system, stenting can be accomplished without resorting to a larger diameter guiding catheter having a larger diameter introducer sheath. Thus, the combination of the S-O-A-W system with the Intro-Angio-Guide system 100 as described herein would provide by far the smallest opening in the access artery as compared to any other system used for stenting a stenosis. Specifically, instead of an outside diameter of the introducer sheath being 8 FR or 9 FR as is typically used during stenting today, the invention described herein would provide an outside diameter for the introducer sheath 40 that could be as small as approximately 5.1 FR. This may be advantageous in order to avoid the need for vascular closure devices and to reduce the possibility of serious bleeding at the groin which occurs in about 3% of all stent cases today and can result in the patient requiring additional treatments such as a blood transfusion.
After the angiography or stenting procedure is completed, it is helpful to retain the introducer sheath 40 at its site through the skin at the groin and into the femoral artery so that the patient's medications can be adjusted without significant blood loss through the opening at the groin. For example, medication to prevent blood clots must be mostly gone from the patient's body before the introducer sheath 40 is removed from its site in the groin. Also, the interventional cardiologist may wish to provide additional medications to the patient at the end of the angiography or stenting procedure. For the introducer sheath 40 to remain in the patient's body with the Angio-Guide catheter 30 removed, it is necessary to have a means to prevent the buckling of the thin wall of the shaft 41 of the introducer sheath 40 as the Angio-Guide catheter 30 is withdrawn from the introducer sheath 40. To accomplish this goal, the guide wire 60 (see
Presented below is a detailed method of how the present invention would be used for stenting of a coronary artery.
The following would replace steps 13-15 if the sheath 40 includes sufficient wire reinforcement such as a flat wire helix as described in U.S. Pat. No. 5,180,376 that the snap on sheath dilator 70 is not necessary.
The following procedure could be used if an additional stenosis is to be stented:
The maneuver described in Step 9 above provides three very important performance enhancements compared to conventional stenting with conventional stent delivery systems and guiding catheters: 1) the Angio-Guide catheter 30, when advanced deeply into the target vessel, will provide much better “backup” support and one-to-one torque control and steering of the S-O-A-W system, to allow passage of the S-O-A-W system through a tortuous and/or severely narrowed target lesion (stenosis); 2) contrast can be injected via the Angio-Guide catheter 30 which provides excellent visualization of the target vessel with minimal contrast use (this provides excellent visualization using much less contrast than required using conventional guiding catheters, thereby reducing the risk of contrast-induced nephropathy, volume overload, reduced cost, etc.); and 3) this system allows the Angio-Guide catheter 30 to be advanced over the body of the S-O-A-W delivery system if a dissection occurs during stenting. The S-O-A-W system is advanced distally beyond the dissection, followed by advancement of Angio-Guide over the S-O-A-W to a true lumen position distal to the dissection; allowing removal of S-O-A-W system and replacement with another S-O-A-W system to repair the dissection, and/or a coronary guidewire to be advanced distally to allow conventional stenting and/or replacement of Angio-Guide catheter 30 with a conventional guiding catheter over the coronary guidewire using an exchange length coronary guide wire.
Various other modifications, adaptations and alternative designs are of course possible in light of the teachings as presented herein. Therefore it should be understood that, while still remaining within the scope and meaning of the appended claims, this invention could be practiced in a manner other than that which is specifically described herein.
