The invention relates to the field of intraluminal catheters, and particularly, to guiding catheters suitable for intravascular procedures such as angioplasty, stent deployment and the like.
In percutaneous transluminal coronary angioplasty (PTCA) procedures, a catheter system is introduced into a patient's vasculature to open up a body lumen, usually a coronary artery, which has become partially blocked by a stenotic lesion. These procedures can also be used to open up other arteries which have become partially blocked, including, but not limited to the carotid arteries and peripheral arteries. The catheter system is usually inserted into the heart to treat a coronary artery by advancing the system through the femoral artery, although it is possible to access the coronary arteries through other arteries in the patient's vasculature.
The catheter system usually includes a guide catheter, often referred to as a guiding catheter, which is used to create an open passageway for the insertion of other catheters which are to be advanced to the target lesion. The guide catheter usually has a pre-shaped distal section which allows it to be positioned in the proper direction once placed in the aortic arch of the patient. The guide catheter is usually percutaneously introduced into the patient's vasculature and then advanced through the patient's vasculature until the shaped distal section of the guide catheter is adjacent to the ostium of a desired coronary artery. The proximal end of the guiding catheter, which extends out of the patient, is torqued to rotate the shaped distal section and, as the distal section rotates, it is guided into the desired coronary ostium. The distal section of the guide catheter is shaped so as to engage a surface of the ascending aorta and thereby seat the distal end of the guide catheter in the desired coronary ostium and to hold the catheter in that position during the procedures when other intravascular devices such a guide wires, balloon catheters and stent catheters are being advanced through the inner lumen of the guiding catheter.
In the typical PTCA or stent delivery procedures, the balloon catheter with a guide wire disposed within an inner lumen of the balloon catheter is advanced within the inner lumen of the guide catheter which has been appropriately positioned with its distal tip seated within the desired coronary ostium. A guide wire is first advanced out of the distal end of the guide catheter into the patient's coronary artery until the distal end of the guide wire crosses a lesion to be dilated or an arterial location where a stent is to be deployed. A balloon catheter is advanced into the patient's coronary anatomy over the previously introduced guide wire until the balloon on the distal portion of the balloon catheter is properly positioned across the lesion. Once properly positioned, the balloon is inflated with inflation fluid one or more times to a predetermined size so that in the case of the PTCA procedure, the stenosis is compressed against the arterial wall, and the wall is expanded to open up the vascular passageway. In the case of stent deployment, the balloon is inflated to plastically expand a stent within the stenotic region where it remains in the expanded condition. Generally, the inflated diameter of the balloon is approximately the same diameter as the native diameter of the body lumen being dilated so as to complete the dilatation or stent deployment but not over expand the artery wall. After the balloon is finally deflated, blood flow resumes through the dilated artery and the dilatation catheter and the guide wire can be removed therefrom. Generally, the stent deployment may be accomplished simultaneously with or after a PTCA procedure has been performed at the stenotic site.
Treatment of the main coronary arteries (left and right) usually requires the guide catheter to be engaged within the ostium of the artery, as will be explained. Unfortunately, the anatomy of the main coronary arteries, particularly the left main coronary artery, can be relatively short and can compromise the support provided by the guiding catheter. Additionally, lesions near the ostium can prevent a deep seating of the distal end of the guide catheter within the ostium. Guide catheter backout can thus occur when an interventional device, such as a balloon catheter, is used within the distal portion of the artery. “Backout” of the guide catheter from the ostium is a term used to describe the action taken by the guide catheter caused by the reactive forces applied to the guide catheter as the interventional device is treating the lesion. As the term implies, the guide catheter will move or back out of the ostium, which is detrimental to its function. As a result, it can be difficult to place a stent in the region where the distal end of the guide catheter is seated, and if the guide catheter is not properly seated, it can back out.
What has been needed is a guide catheter design which would allow the implantations of a stent in the ostium or proximal region of the coronary artery while not compromising the support that is need from the guide catheter for accurate placement of the primary or secondary stents or other treatment devices. The present invention satisfies these and other needs.
The present invention is generally directed to methods for implanting a stent into an ostium or a proximal portion of a body vessel utilizing a guide catheter, rather than a conventional balloon angioplasty catheter, as the primary delivery device. By using the guide catheter as the primary stent delivery catheter, the guide catheter can function both as a conventional guide catheter to allow interventional instruments to be advanced therethrough and as a stent delivery catheter to simultaneously implant a stent in a location of the body vessel which is often difficult to implant a stent with conventional stent delivery devices. The present invention is particularly useful in allowing a physician to accurately implant a stent near the ostium of a main coronary artery branching from the aorta, while still achieving adequate guide catheter support for advancement of secondary treatment devices into the main coronary artery.
The methods of the present invention can utilize a guide catheter which includes a mounting region located at its distal end section upon which a stent can be mounted. Suitable stents which can be placed on the mounting region include, but are not limited to, balloon-expandable stents, self-expanding stent, bio-absorbable stents, drug-eluting stents and composite stents. When a balloon expandable stent is to be implanted, the guide catheter should include an expandable member, such as a balloon, which is adapted to apply an outward radial force which expands the stent into the body lumen. The guide catheter would require a mechanism, such as an inflation lumen and an inflation port, which would be used to inflate the balloon. When a self-expanding stent is to be implanted, usually a retractable sheath would be co-axially disposed over the guide catheter to maintain the self-expanding stent in a collapsed, delivery position. The retractable sheath could be simply retracted to remove the restraint placed on the self-expanding stent, thus allowing the self-expanding stent to radially expand to its expanded position. A retractable sheath also could be used to cover a balloon-expandable, bio-absorbable and drug eluting stents to protect these stents as the guide catheter is being advanced into the patient's vasculature. As a result of using a protective outer sheath, there may be no need to crimp the stent onto the guide catheter, which would be beneficial especially if the stent has a fragile structure or is coated with a drug. The guide catheter can be made similar to conventional devices and include an elongated shaft with a preshaped or shapeable distal shaft section to facilitate placement of the distal tip of the guide catheter into a patient's body lumen.
A method of implanting a stent into a patient's vasculature utilizing a guide catheter includes providing a guide catheter having a distal section, a proximal section and an inner lumen adapted to receive interventional devices therethrough. The distal section of the guide catheter has a stent disposed thereon. The guide catheter and stent are then advanced through the patient's vasculature to a location where a branch vessel, such as the left main coronary vessel, forms from a main vessel, such as the aorta. The distal section of the guide catheter and the stent can then be positioned into the opening, or ostium, of the branch vessel a sufficient distance to anchor the distal section of the guide catheter within the branch vessel. The method further includes implanting the stent at the opening of the branch vessel to treat a stenosis which has formed at or in close proximity of the ostium of the branch vessel.
In a further method of use, an interventional device can be advanced through the lumen of the guide catheter after the stent is implanted. As mentioned above, the guide catheter may include an expandable member upon which the stent is mounted. In using such a guide catheter, the method can include actuating the expandable member to implant the stent in the opening of the branch vessel, which will also help in anchoring the distal section of the guide catheter within the branch vessel. The expandable member can be, for example, an inflatable stent balloon. After the expandable member has been actuated, an additional interventional procedure(s) can be performed on one or more stenoses, lesions or damaged vessel located distal to the ostium by simply using the guide catheter to advance the necessary interventional devices through the lumen of the guide catheter. As a result of this method, the physician does not have to utilize a conventional stent delivery catheter to stent the sometimes difficult to stent ostium of the branch vessel.
As mentioned above, the stent can be covered during the time that the guide catheter is being advanced through the patient's vasculature. The method contemplates retracting the sheath in order to implant the stent. When the stent is a self-expanding type, the simple retraction of the sheath should allow the stent to self-expand to its expanded position. If the stent is a balloon expandable type, the sheath should first be retracted, otherwise the expansion of the balloon could cause the sheath to expand with the stent. Thereafter, the expandable member can be actuated to implant the stent at the area of stenosis in the ostium of the branch vessel. In one particular method of the present invention, the sheath can be made from a bio-absorbable material which starts to dissolve once making contact with the body fluid. In such a method, the sheath does not have to be retracted since the sheath will dissolve in time to expose the stent for implantation.
The guide catheter can be made from suitable polymeric material and may include multistrand reinforcing structure made from metallic or metallic like materials which extend through at least a portion of the shaft section of the guide catheter. The distal section of the guide catheter is usually more flexible to provide atraumatic characteristics to the distal tip. The distal end of the catheter shaft is typically provided with an atraumatic distal tip which can be radiopaque to enhance visibility under a fluoroscope. Additionally, the distal section of the guide catheter can be pre-shaped, common with conventional guide catheters, in order to match the vasculature in which the guide catheter is to be placed. Suitable polymeric materials include, but are not limited to polyimides, polyamide elastomers, e.g., polyether block amides such as PEBAX alone or blended with nylon or PEBAX materials with other durometers. Other suitable polymeric materials include polyurethanes. A variety of other thermoplastic and thermoelastic polymers, copolymers and blends may also be employed.
These and other advantages of the invention will become more apparent from the following detailed description of the invention and the accompanying exemplary drawings.
Referring initially to
The distal section 22 of the guide catheter 10 is shown in
As is shown in
Next, as is depicted in
The above-described method utilizes a balloon expandable stent to be implanted at the ostium of the branch vessel. Other stents can be implanted at the ostium as well. For example, a self-expanding stent can be implanted. A protective sheath is used when implanting a self-expanding stent in order to maintain the stent in a collapsed, delivery position. The sheath and self-expanding stent must first be placed into the ostium 14, as is shown in
Referring again to
While the disclosed method describes the use of the guide catheter in implanting a stent into the ostium of the left main coronary artery, it should be appreciated that the method of the present invention could be used in a number of branch vessels which are susceptible to lesions and stenoses near the ostium of the vessel. For example, the guide catheter could be used to implant a stent at the right main coronary artery 50, shown in
The guide catheter can be made from materials used in conventional guide catheters and balloon dilatation delivery systems. For example, the guide catheter could be made from a polymeric material and may include a reinforcing structure or layer formed from stiffer materials, such as braiding or winding formed from wires. Such construction for a guide catheter is well known in the art. It is contemplated that the reinforcing structure could include strands of wires formed of stainless steel and similar materials. Most of the strands forming the braided reinforcing structure are formed of a high strength, highly radiopaque metal. A substantial portion of the strands can be formed of a variety of other materials that include stainless steel (304) and high strength alloys such as MP35N, Elgiloy, Conichrome, Haynes 242 and L-605 which contain cobalt, chromium and nickel as well as high strength polymeric material. High strength plastic strands (e.g., Kevlar) or mixtures of plastic and metallic strands may also be used to form part of the reinforcing structure of the guide catheter.
Guide catheters designed for coronary artery access have varying lengths, generally between about 90 to about 130 cm, in one embodiment the length is about 100 to about 120 cm. The wall thickness of the catheter shaft can ranges from about 0.003 to about 0.01 inch (0.076-0.254 mm). The guide catheter can have a generally constant outer diameter throughout its length, and the wall thickness can also be generally constant.
It will be apparent from the foregoing that, while particular methods of the invention have been illustrated and described, various modifications can be made without departing from the spirit and scope of the invention. While the description of the invention is directed to embodiments for coronary applications, various modifications and improvements can be made to the invention without departing therefrom.