Balloon catheter with controller depth incising blade

A device for incising tissue to a pre-selected incision depth within a body conduit of a patient includes an elongated balloon catheter and at least one elongated straight blade that is mounted on the balloon. To control the incision depth, each blade has a blunt section formed with a non-incising surface and a cutting edge positioned distally to the blunt section. A proximal portion of the blade is attached to a proximal balloon section, and in operation, the balloon/blade combination is advanced into the body conduit and positioned distal to the target tissue/stenosis. The balloon is then inflated. With this inflation, the blade is inclined relative to the axis of the catheter with an increasing distance between the blade and the axis in a distal direction. The device is then withdrawn, proximally, to incise the tissue/stenosis.

FIELD OF THE INVENTION

The present invention pertains generally to subcutaneous, 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 at a controlled cutting depth. The present invention is particularly, but not exclusively, useful for incising an aortic valve stenosis with a catheter having a blade configured to incise at a pre-selected cutting depth.

BACKGROUND OF THE INVENTION

The creation of superficial incisions within a body conduit can be used for several purposes. For example, a properly placed incision can be used to facilitate the dilation of the conduit's lumen when the conduit is stenosed or otherwise blocked. Applications where the creation of an incision is beneficial can include, but are not limited to, the dilation of vessels and valves in the vasculature. Other conduits where incisions can be used for dilation and other purposes include the esophagus, urethra and portions of the airway system. For some (if not all) of these applications, it is important to control the depth of the incision. If the incision is too shallow, the incision will be ineffective in promoting dilation of the conduit lumen. On the other hand, if the incision is too deep, the incision can cause damage to underlying tissue. This underlying tissue can include vital organs, nerves and nerve endings, and other delicate anatomical structures, the damage of which may be irreparable.

One exemplary application which warrants further discussion is the incision and dilation of the aortic valve as a treatment for Aortic Valve Stenosis (AS). Functionally, 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 in which 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 in its entirety.

As indicated above, in some applications, it is important to control the depth of the incision. In this regard, the present invention is directed to a percutaneous device and method for making incisions in a body conduit having a controlled, pre-selected incision depth. Preferably, the invention provides a cutting device for treating aortic valve stenosis by making controlled depth incisions in the aortic valve to thereby establish a more normal flow of blood from the left ventricle of the heart into the aorta.

SUMMARY OF THE INVENTION

In accordance with the present invention, a device for incising to a pre-selected incision depth within a body conduit of a patient includes a catheter having an elongated balloon mounted near its proximal 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 substantially straight, elongated blades are attached to the balloon. Each blade defines a blade axis 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 control the incision depth, each blade has a blunt section formed with a non-incising surface that extends completely around the blade axis. In more detail, the blunt section is positioned proximally from the distal blade end to interpose a cutting edge between the non-incising surface and the distal blade end. The non-incising surface can be attached to a portion of the blade having the cutting edge or integrally formed thereon. In one embodiment of the present invention, the non-incising surface includes a rounded surface portion. For example, a blade can be formed initially having a sharp blade edge that extends from the distal blade end to the proximal blade end and thereafter a proximal portion of the sharp blade edge can be rounded to create the non-incising surface.

In another embodiment of the blade, a protective sheath can be positioned to overlay a proximal portion of the sharp blade edge. In one implementation, a plastic, tubular shaped protective sheath is used to cover a proximal portion of the sharp blade edge. In yet another embodiment of the blade, a spherical shaped member having a substantially spherical non-incising surface is formed at a location on the blade proximal to the distal blade end. In a particular implementation of this embodiment, the spherical member is sized having a diameter, 2 r, that is larger than the blades maximum dimension, d, normal to the blade axis (d<2 r). For all of these blade embodiments, a blunt section having a non-incising surface is created to control (i.e. limit) the incision depth.

In the operation of the present invention, the balloon (in its deflated configuration) is advanced into the body conduit (e.g. vasculature) of the patient. Specifically, for the exemplary case where the invention is used for the treatment of AS, 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. Thus, the angle of the blade can be any angle suitable for an angioplasty balloon. Preferably, this angle (α) is in a range between approximately zero degrees and approximately forty-five degrees (0°<α<45°). As a consequence of this cooperation of structure, when the balloon is in its inflated configuration, the cutting edges of the blade(s) are presented for cutting (incising) the aortic valve. More specifically, the distal ends 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. Specifically, the cutting edge penetrates the tissue or lesion to be incised until the non-incising surface contacts the tissue/lesion. At this point, the incision depth is set and further withdrawal of the inflated balloon results in an incision having a somewhat constant, controlled incision depth. 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.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring initially toFIG. 1, a system for incising tissue in accordance with the present invention is shown and generally designated10. As shown, the system10includes a catheter12which has a proximal end14and a distal end16. System10also has an inflatable, elongated balloon18that is mounted on the catheter12near its distal end16. Further, it is seen that a y-site20is attached to the proximal end14of the catheter12. Specifically, the y-site20allows the catheter12to be operationally engaged with a guidewire22for the purpose of advancing the catheter12over the guidewire22after the guidewire22has been pre-positioned in a body conduit, such as the vasculature, of a patient (not shown).FIG. 1also shows that an inflation/deflation device24can be connected to the y-site20for fluid communication with the balloon18.

For the catheter12, the inflatable balloon18can 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 toFIG. 1, it will be seen that the system10of the present invention includes a plurality of substantially straight blades26, of which the blades26aand26bare only exemplary. The system10may include only one such blade26, or it may include more than one blade26(e.g. two, three or more). With this in mind, and using the blade26aas a specific example for purposes of disclosure, it will be seen that the proximal end28of the blade26ais positioned adjacent, or near, the proximal end30of the balloon18. Further, it is to be appreciated that the blade26ais oriented on the balloon18so that it is coplanar with the longitudinal axis32of the balloon18(seeFIG. 2A). Also, it is to be appreciated by cross-referencingFIG. 1withFIG. 2B, that the blade26ais attached to a proximal section of the balloon18. For purposes of the present invention, the blades26can be attached to the balloon18by any means well known in the pertinent art, such as by bonding.

The structure for balloon18will be best understood by referencing bothFIGS. 1 and 2B. As shown, the balloon18, when inflated, generally defines three sections. These are: a proximal section34; an intermediate section36; and a distal section38. More specifically, when the balloon18is inflated, the proximal section34is generally conical-shaped and has a taper with an increasing radius in the distal direction. On the other hand, the intermediate section36is substantially cylindrical-shaped and has a generally constant radius. Also, there is a conical-shape for the distal section38. This time, however, the taper for the distal section38has a decreasing radius in the distal direction. Preferably, the blade26ais longer than the proximal section34and is attached to only the proximal section34of the balloon18. Consequently, the distal end40of the blade26ais not engaged with the balloon18. As perhaps best seen inFIG. 2B, this cooperation of structure allows the distal end40of the blade26a, to extend radially outward from the axis32to a greater distance than the radius of the cylindrical-shaped intermediate section36. Stated differently, with the balloon18in its inflated configuration, the blades26are inclined at an angle (α) relative to the axis32. Preferably, the angle (α) is in a range between 0° and 45°.

FIG. 1also shows that the system10of the present invention can include radiopaque markers44aand44bto assist the operator in positioning the balloon18in the vasculature of the patient. Identification of the balloon18at a location in the vasculature can be further facilitated by using a contrast medium to inflate the balloon18. Other mechanisms, well known in the pertinent art, can be incorporated in the system10and used for these purposes.

As envisioned for the present invention, the balloon18of the present invention can be reconfigured between a deflated configuration (FIGS. 2A and 3A) and an inflated configuration (FIGS. 2B and 3B). The actual inflation and deflation of the balloon18is accomplished by manipulating the inflation device24(SeeFIG. 1). Specifically, for this purpose, the inflation/deflation device24is connected at the y-site20in fluid communication with an inflation lumen46(seeFIG. 4). A manipulation of the plunger48(seeFIG. 1) can then cause the balloon18to selectively inflate or deflate.FIG. 4also shows that the catheter12is formed with a guidewire lumen50for receiving the guidewire22therethrough.

As best seen inFIG. 5, each blade26has a sharp blade edge52and includes a blunt section54having a non-incising surface56to control incision depth. For the blade26shown inFIGS. 1-5, the blunt section54consists of a tubular shaped, protective sheath58that is positioned to overlay a distal portion of sharp blade edge52. More specifically, for this embodiment, the sharp blade edge52extends from a distal edge end60to a proximal edge end62and the protective sheath58overlays and covers a proximal portion of the sharp blade edge52. It can further be seen that the elongated blade26defines a blade axis64and the non-incising surface56of the blunt section54extends completely around the blade axis64. Moreover, the blunt section54is positioned proximally from the distal end40of the blade26to project an exposed cutting edge42distally from the blunt section54. For this embodiment of the blade26, the blunt section54can be, but is not limited to, a sheath58that encapsulates a proximal portion of the blade26(as shown) or a coating (not shown) that is applied directly to the sharp blade edge52. In a particular embodiment, the protective sheath58can be made of a polymeric material (e.g. plastic) and bonded to a proximal portion of the blade26.

FIG. 6shows another embodiment of a blade (designated126) having a blunt section154for use in the system10shown inFIG. 1to control incision depth. As shown inFIG. 6, the blunt section154is positioned proximally from the distal end140of the blade126to project an exposed cutting edge142distally from the blunt section154.FIG. 6also shows that the blunt section154establishes a non-incising surface156, which includes a rounded surface portion66, and extends completely around the blade axis164. With this cooperation of structure, the blade126can be used in the system10to effect a controlled depth incision. In an exemplary manufacturing method, the blade126can be prepared by initially forming a blade blank (not shown) having a sharp blade edge that extends the entire length of the blade blank. Next, a proximal portion of the sharp blade edge can be rounded (i.e. dulled) to create the non-incising surface156.

Referring now toFIG. 7, another embodiment of a blade (designated226) is shown having a blunt section254for use in the system10shown inFIG. 1to control incision depth. As shown inFIG. 7, the blunt section254is positioned proximally from the distal end240of the blade226to project an exposed cutting edge242distally from the blunt section254.FIG. 7also shows that the blunt section254establishes a non-incising surface256which is substantially spherical, and extends completely around the blade axis264. For the embodiment shown inFIG. 7, the spherical, blunt section254is sized having a diameter, 2 r, that is larger than the maximum dimension, d, of the blade226, normal to the blade axis264(d<2 r). With this cooperation of structure, the blade226can be used in the system10to effect a controlled depth incision.

FIG. 8shows yet another embodiment of a blade (designated326) having a blunt section354for use in the system10shown inFIG. 1to control incision depth. As shown inFIG. 8, the blunt section354is positioned proximally from the distal end340of the blade326to project an exposed cutting edge342distally from the blunt section354.FIG. 8also shows that the blunt section354establishes a non-incising surface356, which is substantially cylindrical shaped, and extends completely around the blade axis364. In a typical embodiment, the blunt section354is formed as a wire and then attached to the remaining portion of the blade326that includes the cutting edge342. With this cooperation of structure, the blade326can be used in the system10to effect a controlled depth incision.

Referring now toFIG. 9, an exemplary application of the system10is illustrated wherein the system10is used to treat Aortic Valve Stenosis. Although the exemplary treatment of an aortic valve stenosis is hereinafter described, it is to be appreciated that the system10can be used to incise tissue (including stenosed tissue) in other areas of the body. For the procedure, a guidewire22is first pre-positioned in the vasculature of the patient. Next, the catheter12, with the balloon18in its deflated configuration (i.e. as shown inFIGS. 2A and 3A) is then advanced over the guidewire22. Specifically, as shown, the balloon18is advanced over the guidewire22until the balloon18has been positioned in the left ventricle68of the patient's heart. At this point, the inflation/deflation device24is manipulated to inflate the balloon18into its inflated configuration (FIGS. 1,2B and3B). With the cutting blades26radially deployed, the system10is then withdrawn in a proximal direction through the aortic valve70and into the aorta72. During this withdrawal, the cutting edges42of respective blades26incise the aortic valve70to relieve any stenosis that has developed in the aortic valve70. After incision, the balloon18is deflated, and the system10is removed from the vasculature of the patient.

While the particular Balloon Catheter With Controlled Depth Incising Blade and corresponding methods of manufacture and 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 or design herein shown other than as described in the appended claims.