Patent Application
20060116700
The present invention pertains generally to interventional medical devices. More particularly, the present invention pertains to catheters that can be used to incise target tissue in the vasculature of a patient while minimizing collateral damage to non-target tissue. The present invention is particularly, but not exclusively, useful for incising an aortic valve stenosis with a catheter having a blade to prevent the inadvertent incision of non-target tissue.
The aortic valve controls the flow of oxygen-rich blood from the left ventricle into the aorta. Anatomically, the aortic valve consists of three semilunar cusps (i.e. right, left and posterior cusps) that are attached around the circumference of an opening that is located between the aorta and left ventricle. During each heart cycle, the cusps (also called flaps or leaflets) fold back against the inside wall of the aorta as the left ventricle contracts, effectively opening the aortic valve to allow blood to be pumped through the aorta and into the arteries in the vasculature of the body. Between contractions of the left ventricle, however, the cusps extend into the passageway between the left ventricle and aorta to close the aortic valve and form a tight seal that prevents blood from leaking back into the left ventricle from the aorta.
For any of several reasons (e.g. aging, or birth defects), it can happen that the aortic valve is somehow damaged and may become stenosed. When this happens, the aortic valve does not open to its normal extent and the flow of blood from the heart into the aorta is constricted. This leads to an undesirable heart condition that is commonly known as aortic valve stenosis (AS). If left untreated, AS can worsen and lead to a number of complications including endocarditis, arrhythmia and in some cases heart failure.
Heretofore, the conventional methods used to treat AS have typically involved either an aortic valve replacement or a procedure commonly known as percutaneous balloon valvuloplasty. In the case of a valve replacement, an extensive surgical procedure is generally required wherein the aortic valve is replaced either by a mechanical or a porcine valve. On the other hand, being a percutaneous procedure, balloon valvuloplasty is somewhat less involved than a valve replacement procedure. Nevertheless, for many reasons including a high recurrence rate, and despite its initial acceptance, balloon valvuloplasty is now used infrequently and only palliatively or as a bridge to a subsequent valve replacement.
More recently, efficacious treatments for aortic valve stenosis have been developed which entail incising and dilating the stenosed aortic valve. For example, a device and method for treating AS is disclosed in co-pending, co-owned U.S. patent application Ser. No. 10/353,827, filed by Leonard Schwartz (Schwartz '827) on Jan. 27, 2003, for an invention titled “A Device for Percutaneous Cutting and Dilating a Stenosis of the Aortic Valve”, and which is hereby incorporated by reference herein.
The present invention is directed to efficacious percutaneous devices and methods for treating a stenosis in a body conduit and is particularly applicable to the treatment of a valvular stenosis.
In accordance with the present invention, a cutting device having a blade for treating a stenosis in a lumen or a valvular stenosis includes a catheter having an elongated balloon mounted near its distal end. As intended for the present invention, the balloon can be reconfigured on the catheter between an inflated configuration and a deflated configuration. Structurally, the balloon defines an axis and, in its inflated configuration, it has at least three identifiable sections that are located between its proximal end and its distal end. These sections are: a substantially conical-shaped proximal section having a taper with an increasing radius in the distal direction; a substantially conical-shaped distal section having a taper with a decreasing radius in the distal direction; and a substantially cylindrical-shaped intermediate section that is located between the proximal section and the distal section.
One or more elongated blades, that are typically substantially straight, are attached to the balloon. For the present invention, each blade is formed with a sharp edge and extends from a distal blade end to a proximal blade end. In a particular embodiment of the cutting device, a proximal portion of each blade is attached to the proximal section of the balloon. On the other hand, for this embodiment, the distal end of each blade is detached from the balloon to allow the blade to incline relative to the balloon axis when the balloon is inflated.
To reduce the likelihood of inadvertent tissue incision by the distal end of each blade during a movement of the blade, each blade has a blunt tip member at the blade's distal end. The blunt tip member can be attached to the portion of the blade having the cutting edge or integrally formed thereon. For example, in one embodiment of the present invention, the blunt tip member includes a fine coil wire and ball shaped element. More particularly, a fine coil wire having a distal end and a proximal end is provided, with the ball shaped element located at the distal end of the coil wire. In another embodiment of the present invention, the blunt tip member includes a protective sheath. For this embodiment, the cutting edge extends from a cutting edge distal end to a cutting edge proximal end and the protective sheath is positioned to overlay the distal end of the cutting edge. For example, the protective sheath can be made of plastic and bonded to the portion of the blade having the cutting edge. In yet another embodiment, the blunt tip member is formed as a rounded surface to prevent tissue incision by the distal tip of the blade.
In the operation of the present invention, the balloon (in its deflated configuration) is advanced into the vasculature of the patient. Specifically, for one exemplary treatment wherein AS is treated, the balloon is routed through the aorta and positioned inside the left ventricle of the heart. This then places the balloon distal to the aortic valve. Once the balloon is in the left ventricle it is then inflated.
In its inflated configuration, the balloon inclines each blade relative to the axis of the balloon. Specifically, this inclination is characterized by an increasing distance between the blade and the axis of the balloon, in a distal direction along the axis. In cooperation with the balloon, each blade is inclined relative to the balloon's axis at an angle (α) that is established by the taper of the balloon's proximal section, when the balloon is inflated. Preferably, this angle (α) is in a range between approximately zero degrees, when the balloon is in its deflated configuration, and approximately forty-five degrees, when the balloon is in its inflated configuration, (0°-45°). As a consequence of this cooperation of structure, when the balloon is in its inflated configuration, the sharp edges of the blade(s) are presented for cutting (incising) the aortic valve. More specifically, the distal portions and distal ends (including the blunt tip member) of the respective blade(s) are projected radially outward from the axis through a distance that extends beyond the radius of the cylindrical-shaped intermediate section.
An incising action on the aortic valve is accomplished as the inflated balloon is withdrawn through the aortic valve in a proximal direction. After the inflated balloon has been withdrawn through the aortic valve, and the valve has been incised, the balloon is deflated, retracting each blade into its original, non-inclined orientation. The deflated balloon and retracted blade(s) are then removed from the vasculature to complete the procedure.
The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which:
Referring initially to
For the catheter 12, the inflatable balloon 18 can be made of a compliant, semi-compliant or non-compliant material. Specifically, any suitable thermoplastic or thermosetting material may be used in accordance herewith including both elastomeric and non-elastomeric materials. Thermoplastic materials find particular utility herein. Examples of non-elastomeric materials include, but are not limited to, polyolefins including polyethylene and polypropylene, polyesters, polyethers, polyamides, polyurethanes, polyimides, and so forth, as well as copolymers and terpolymers thereof. As used herein, the term “copolymer” shall hereinafter be used to refer to any polymer formed from two or more monomers.
Examples of suitable elastomeric materials include, but are not limited to, elastomeric block copolymers including the styrenic block copolymers such as styrene-ethylene/butylene-styrene (SEBS) block copolymers disclosed in U.S. Pat. No. 5,112,900 which is incorporated by reference herein in its entirety. Other suitable block copolymer elastomers include, but are not limited to, styrene-isoprene-styrene (SIS), styrene-butadiene-styrene (SBS), styrene-isobutylene-styrene (SIBS) and so forth. Block copolymer elastomers are also described in commonly assigned U.S. Pat. Nos. 6,406,457, 6,171,278, 6,146,356, 5,951,941, 5,830,182 and 5,556,383, each of which is incorporated by reference herein in its entirety.
Elastomeric polyesters and copolyesters may be employed herein. Examples of elastomeric copolyesters include, but are not limited to, poly(ester-block-ether) elastomers, poly(ester-block-ester) elastomers and so forth. Poly(ester-block-ether) elastomers are available under the trade name of HYTREL® from DuPont de Nemours & Co. and consist of hard segments of polybutylene terephthalate and soft segments based on long chain polyether glycols. These polymers are also available from DSM Engineering Plastics under the trade name of ARNITEL®.
Non-elastomeric polyesters and copolymers thereof may be employed, such as the polyalkylene naphthalates, including polyethylene terephthalate and polybutylene terephthalate, for example. Polyamides including nylon, and copolymers thereof, such as poly (ether-block-amides) available under the trade name of PEBAX® from Atofina Chemicals in Philadelphia, Pa., are suitable for use herein. Suitable balloon materials are described in commonly assigned U.S. Pat. Nos. 5,549,552, 5,447,497, 5,348,538, 5,550,180, 5,403,340 and 6,328,925, each of which is incorporated by reference herein in its entirety. The above lists are intended for illustrative purposes only, and shall not be construed as a limitation on the scope of the present invention.
Still referring to
The structure for balloon 18 will be best understood by referencing both
As envisioned for the present invention, the balloon 18 of the present invention can be reconfigured between a deflated configuration (
As best seen in
Referring now to
Referring now to
While the particular Aortic Stenosis Cutting Balloon Blade and corresponding methods of use as herein shown and disclosed in detail are fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that they are merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction, design or use herein shown other than as described in the appended claims.
