US20100023037A1 - Ultrasound catheter and methods for making and using same - Google Patents

Abstract

Ultrasound catheter devices and methods provide enhanced disruption of blood vessel obstructions. Generally, ultrasound catheters include an elongate flexible catheter body with one or more lumens, an ultrasound transmission member extending longitudinally through the catheter body lumen and, in some embodiments, a guidewire tube extending through the lumen. A distal head for disrupting occlusions is coupled with the distal end of the ultrasound transmission member and is positioned adjacent the distal end of the catheter body. Some embodiments include improved features such as a bend in the catheter body for enhancing positioning and/or advancement of the catheter.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS
• This application is a continuation of U.S. patent application Ser. No. 10/345,078, entitled Ultrasound Catheter and Methods for Making and Using Same, filed on Jan. 14, 2003 which is related to pending U.S. patent application Ser. No. 10/229,371, entitled “Ultrasound Catheter for Disrupting Blood Vessel Obstructions,” the full disclosures of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
• The present invention relates generally to medical devices and methods. More specifically, the present invention relates to ultrasound catheter devices, methods for making the devices, and methods for using the devices to disrupt blood vessel occlusions.
• Catheters employing various types of ultrasound transmitting members have been successfully used to ablate or otherwise disrupt obstructions in blood vessels. Specifically, ablation of atherosclerotic plaque or thromboembolic obstructions from peripheral blood vessels such as the femoral arteries has been particularly successful. To disrupt occlusions of small blood vessels, such as coronary arteries or peripheral vessels, ultrasound catheters typically have configurations—size, flexibility, shape and the like—which allow for their advancement through the tortuous vasculature of the aortic arch, coronary tree, peripheral vasculature or other similarly narrow vessels.
• Typically, an ultrasound catheter transmits energy from an ultrasound transducer through a transducer horn and then a transmission member, such as a wire, to a distal tip or distal head. Ultrasound energy propagates through the transmission member as a sinusoidal wave to cause the distal head to vibrate. Such vibrational energy is typically utilized to ablate or otherwise disrupt vascular obstructions. Various ultrasonic catheter devices have been developed for use in ablating or otherwise removing obstructive material from blood vessels. For example, U.S. Pat. Nos. 5,267,954 and 5,380,274, issued to the inventor of the present invention and hereby incorporated by reference, describe ultrasound catheter devices for removing occlusions. While many ultrasound catheters have been developed, however, improvements are still being pursued.
• To effectively reach various sites for treatment of intravascular occlusions, ultrasound catheters often have lengths of about 150 cm or longer. To reach some sites, such as arterial side-branches, it is often necessary to form a bend in the ultrasound catheter. Such bends are often crudely made in an operating room, vascular suite or other setting by a surgeon, cardiologist, interventional radiologist or other physician manually bending the catheter with pliers, surgical forceps or some other instrument. This technique has several drawbacks. First, it is inaccurate and does not always result in a bend at a desired location along the catheter or in a bend having a desired angle. Second, because the user bends the catheter when the catheter is already assembled, with the transmission member already in place, a strain is placed on the transmission member by the bending process. The transmission member is typically bent to as acute of an angle as the catheter body is bent, and the bending process itself stresses the transmission member. Even slight stresses placed on the transmission member by such a bending procedure may cause the transmission member to break prematurely, leading to a reduced usable life for the ultrasound catheter. This susceptibility for premature breakage is compounded by the fact that currently available ultrasonic transmission wires typically break toward their distal ends, where the cross-sectional areas of the wires become smaller.
• Therefore, a need exists for ultrasound catheter devices and methods for making and using such devices that include at least one bend for enhancing positioning and/or advancement of the catheter in a blood vessel. Ideally, such catheter devices would be durable enough to last longer than a conventional ultrasound catheter that is hand-bent by a surgeon or other user immediately before use. Ultrasound catheters may also benefit from additional improvements, such as over-the-wire configurations, improved configurations of a distal head of the catheter, catheters that allow for various modes of operation, catheters with enhanced lubricity and the like. At least some of these objectives will be met by the present invention.
BRIEF SUMMARY OF THE INVENTION
• Ultrasound catheter devices and methods of the present invention provide enhanced disruption of blood vessel obstructions. Generally, ultrasound catheters include an elongate flexible catheter body with at least one lumen, an ultrasound transmission member extending longitudinally through the lumen and, in many embodiments, a guidewire tube extending through the lumen. A distal head for disrupting occlusions is coupled with the distal end of the ultrasound transmission member and is positioned adjacent the distal end of the catheter body. Various embodiments include novel features such as a bend in the catheter body to facilitate positioning and/or advancement of the catheter, over-the-wire configurations, improved configurations of a distal head of the catheter, catheters that allow for various modes of operation, catheters with enhanced lubricity and the like. Methods for making ultrasound catheters may include methods for making a bend in the catheter, methods for sterilizing a catheter using electron-beam radiation and/or the like.
• In one aspect of the invention, an ultrasound catheter for disrupting occlusions in blood vessels comprises an elongate flexible catheter body having a proximal end, a distal end, at least one lumen, and at least one bend in the catheter body nearer the distal end than the proximal end. The catheter also includes an ultrasound transmission member extending longitudinally through the lumen of the catheter body, the ultrasound transmission member having a proximal end connectable to a separate ultrasound generating device and a distal end disposed adjacent the distal end of the catheter body. Finally, the catheter includes a distal head coupled with the distal end of the ultrasound transmission member, the distal head positioned adjacent the distal end of the catheter body.
• Generally, the bend in the catheter may be placed in any desired location and have any desired angle, relative to the longitudinal axis of the catheter body. In some embodiments, for example, the bend in the catheter body is disposed along the catheter body at a location between 5 mm and 30 mm from the distal end. In some embodiments, the bend in the catheter body has an angle of less than 90 degrees. For example, the bend may have an angle of between 20 degrees and 50 degrees in some embodiments. In some embodiments, the bend in the catheter body causes a corresponding bend in the ultrasound transmission member. In this case, sometimes the bend in the catheter body has an angle greater than a corresponding angle of the corresponding bend in the ultrasound transmission member. Optionally, the catheter may further include a sheath disposed over at least a portion of the distal end of the catheter body for maintaining the bend in the catheter body. For example, the sheath may be disposed over the portion of the distal end during non-use of the catheter and is removed from the catheter body before use. In some embodiments, the catheter may further include a hydrophilic coating disposed along an outside surface of at least a portion of the catheter body. The hydrophilic coating may be any suitable coating.
• The distal head of the catheter device may have any of a number of different configurations and features. For example, in some embodiments the distal head is not directly affixed to the distal end of the catheter body. Some embodiments further include at least one side-opening through a side of the distal head. The side-opening may comprise, for example, a space for introducing an adhesive to couple the distal head with a guidewire tube disposed in the lumen of the catheter body. Optionally, the side-opening may extend around at least a portion of a circumference of the distal head. For example, the side-opening may take the form of a slot.
• Some embodiments of the ultrasound catheter include a guidewire tube having a proximal end and a distal end and extending longitudinally through at least a portion of the lumen of the catheter body and through at least a portion of the distal head. The guidewire tube may comprise any suitable material such as, in some embodiments, a polyimide material. In some embodiments, the guidewire tube is affixed to the distal head. Furthermore, the guidewire tube may also be affixed to the catheter body. The side-opening in the distal head, as just described, may sometimes be used for introducing adhesive to affix the distal head to a guidewire tube. For example, the catheter may include a side-opening in the distal head and a polymer sleeve disposed around a portion of the distal head, the polymer sleeve being coupled with the guidewire tube by adhesive extending through the side-opening.
• A guidewire tube of an ultrasound catheter may be an over-the-wire tube, a rapid-exchange tube, a monorail tube or any other suitable guidewire tube. In some embodiments, for example, the proximal end of the guidewire tube exits the catheter body nearer the proximal end of the catheter body than the distal end of the catheter body. Alternatively, the guidewire tube may exit the catheter body nearer the distal end of the catheter body than the proximal end of the catheter body. In still other embodiments, the proximal end of the guidewire tube exits the catheter body through the proximal end of the catheter body. The last of these embodiments may further include a connector device coupled with the proximal end of the catheter body and the proximal end of the guidewire tube, wherein the guidewire tube extends through at least a portion the connector device. Such a catheter may further comprise a coupling member, such as a sheath or sleeve, for coupling the connector device with the catheter body. In other embodiments, the guidewire tube may exit the catheter body through a guidewire port positioned along the catheter body at a location separate from the connector device. Such a guidewire port may sometimes include a flexible extension. In some embodiments, the guidewire tube may include micro-perforations or apertures along all or a portion of its length. The micro-perforations may allow, for example, passage of fluid into the guidewire lumen to provided lubrication to a guidewire.
• In some embodiments, the connector device just described includes a distal portion for coupling with the proximal end of the catheter body, the distal portion having a common lumen. The device further includes a proximal ultrasound transmission arm having an ultrasound transmission lumen in communication with the common lumen and a proximal guidewire arm having a guidewire lumen in communication with the common lumen. Optionally, the connector device may also include a proximal infusion arm having an infusion port in communication with the common lumen. In some embodiments, the ultrasound transmission arm, the distal portion, and the catheter body are disposed along a common longitudinal axis. In some embodiments, the guidewire arm branches from the distal portion of the connector at less of an angle than the infusion arm branches from the distal portion of the connector. Any such embodiments may further include a coupling member for coupling the distal portion of the connector device with the catheter body.
• In some embodiments of the catheter, the ultrasound transmission member may transmit ultrasound energy from the separate ultrasound device as both pulsed energy and continuous energy. Such embodiments may optionally include an actuator coupled with the ultrasound generating device for switching between transmission of the pulsed energy and transmission of the continuous energy to the ultrasound transmission member. Any of the above embodiments may be sterilized by exposure to an electron beam.
• In another aspect, an ultrasound catheter for disrupting occlusions in blood vessels comprises: an elongate flexible catheter body having a proximal end, a distal end, at least one lumen extending longitudinally through the body; an ultrasound transmission member extending longitudinally through the lumen of the catheter body, the ultrasound transmission member having a proximal end connectable to a separate ultrasound generating device and a distal end disposed adjacent the distal end of the catheter body; and a distal head coupled with the distal end of the ultrasound transmission member, the distal head positioned adjacent the distal end of the catheter body; wherein the ultrasound transmission member transmits at least two different types of ultrasound energy from the separate ultrasound generator. In some embodiments, the catheter may further include at least one bend in the catheter body near the distal end. Optionally, the separate ultrasound generating device may include an actuator for switching between transmitting a first type of ultrasound energy to the ultrasound transmission member and transmitting at least a second type of ultrasound energy to the ultrasound transmission member. For example, the first type of ultrasound energy may comprise pulsed ultrasound energy and the second type of ultrasound energy may comprise continuous ultrasound energy.
• In another aspect, an ultrasound catheter for disrupting occlusions in blood vessels includes an elongate flexible catheter body having a proximal end, a distal end, an external surface, an internal surface, at least one lumen, and a hydrophilic coating disposed along at least a portion of the external surface. The catheter also includes an ultrasound transmission member extending longitudinally through the lumen of the catheter body, the ultrasound transmission member having a proximal end connectable to a separate ultrasound generating device and a distal end disposed adjacent the distal end of the catheter body. Finally, the catheter includes a distal head coupled with the distal end of the ultrasound transmission member, the distal head positioned adjacent the distal end of the catheter body. In some embodiments, the catheter further comprises at least one bend in the catheter body.
• In another aspect, an ultrasound catheter for disrupting occlusions in blood vessels comprises: an elongate flexible catheter body having a proximal end, a distal end, at least one lumen extending longitudinally through the body; an ultrasound transmission member extending longitudinally through the lumen of the catheter body, the ultrasound transmission member having a proximal end connectable to a separate ultrasound generating device and a distal end disposed adjacent the distal end of the catheter body; and a distal head coupled with the distal end of the ultrasound transmission member, the distal head positioned adjacent the distal end of the catheter body, wherein the ultrasound catheter is sterilized by exposure to an electron beam. Some embodiments of such catheters may further include a bend in the catheter body near the distal end.
• In another aspect, an improved ultrasound catheter of the type comprising an elongate flexible catheter body having a proximal end, a distal end, and at least one lumen, an ultrasound transmission member extending longitudinally through the lumen of the catheter body, and a distal head coupled with a distal end of the ultrasound transmission member, includes an improvement comprising at least one bend in the catheter body nearer the distal end of the catheter body than the proximal end.
• In still another aspect, an improved ultrasound catheter of the type comprising an elongate flexible catheter body having a proximal end, a distal end, and at least one lumen, an ultrasound transmission member extending longitudinally through the lumen of the catheter body, and a distal head coupled with a distal end of the ultrasound transmission member, includes an improvement comprising a hydrophilic coating disposed along at least a portion of an external surface of the catheter body.
• In another aspect, an ultrasound system for disrupting occlusions in blood vessels comprises an ultrasound catheter, which includes: an elongate flexible catheter body having a proximal end, a distal end, at least one lumen, and at least one bend in the catheter body nearer the distal end than the proximal end; an ultrasound transmission member extending longitudinally through the lumen of the catheter body, the ultrasound transmission member having a proximal end and a distal; and a distal head coupled with the distal end of the ultrasound transmission member, the distal head positioned adjacent the distal end of the catheter body. The ultrasound system also includes a separate ultrasound generating device coupled with the proximal end of the ultrasound transmission member.
• In some embodiments, the separate ultrasound generating device includes an actuator for switching between transmitting a first type of ultrasound energy to the ultrasound transmission member and transmitting at least a second type of ultrasound energy to the ultrasound transmission member. For example, in some embodiments the first type of ultrasound energy comprises pulsed ultrasound energy and the second type of ultrasound energy comprises continuous ultrasound energy.
• In yet another aspect, a method of making an ultrasound catheter for disrupting occlusions in blood vessels comprises forming a catheter body over a mandrel, wherein the mandrel includes at least one bend for forming a corresponding bend in the catheter body; separating the catheter body from the mandrel. The method then involves inserting an ultrasound transmission member into a lumen of the catheter body, wherein inserting the ultrasound transmission member reduces an angle of the at least one bend in the catheter body.
• Any angles, locations or the like for one or more angle(s) may be used. For example, in one embodiment the method comprises forming the body over a mandrel having a bend of between about 20 degrees and about 90 degrees. In some embodiments, inserting the ultrasound transmission member into the lumen reduces the angle of the bend in the catheter body to between 15 degrees and 80 degrees. Sometimes, inserting the ultrasound transmission member into the lumen causes the ultrasound transmission member to bend at the bend in the catheter body. In some embodiments, for example, the ultrasound transmission member bends at an angle less than the angle of the bend in the catheter body. Optionally, some embodiments of the method for making the catheter further include placing a sheath over at least a portion of the catheter body to maintain the bend in the catheter body. Also optionally, some embodiments further involve directing an electron beam at the ultrasound catheter to sterilize the catheter.
• In still another aspect, a method of making an ultrasound catheter for disrupting occlusions in blood vessels comprises placing a catheter body over a mandrel, wherein the mandrel includes at least one bend for forming a corresponding bend in the catheter body, heating the catheter body, removing the catheter body from the mandrel, and inserting an ultrasound transmission member into a lumen of the catheter body, wherein inserting the ultrasound transmission member reduces an angle of the at least one bend in the catheter body.
• In another aspect, a method for disrupting an occlusion in a blood vessel comprises positioning an ultrasound catheter in the blood vessel such that a distal end of the catheter is adjacent the occlusion, transmitting a first type of ultrasound energy to an ultrasound transmission member of the ultrasound catheter to disrupt the occlusion, and transmitting a second type of ultrasound energy to the ultrasound transmission member to further disrupt the occlusion. In some embodiments of the method, the first type of ultrasound energy comprises pulsed energy and the second type of energy comprises continuous energy. In other embodiments, the first type of ultrasound energy comprises continuous energy and the second type of energy comprises pulsed energy. The method may further comprise switching from transmitting the second type of ultrasound energy to transmitting the first type of ultrasound energy. Any of these methods may also include repeating at least one of the transmitting and switching steps at least once.
• In some cases, transmitting the first type of energy and transmitting the second type of energy involves activating an actuator on a separate ultrasound generating device coupled with the ultrasound catheter. In some embodiments, positioning the catheter comprises using a bend in the ultrasound catheter to advance the catheter into a position adjacent the occlusion. The method may further comprise using a bend in the catheter to reposition the ultrasound catheter in an additional blood vessel adjacent an additional occlusion and transmitting at least one form of ultrasound energy to the ultrasound transmission member to disrupt the additional occlusion.
• In any of the above methods, positioning the device may involve advancing the ultrasound catheter over a guidewire. Such advancing of the ultrasound catheter over the guidewire may involve advancing over a guidewire disposed in a guidewire lumen of the catheter, the guidewire lumen extending at least a majority of a length of the catheter. Optionally, the guidewire lumen may extend the full length of the catheter and may be coupled with a connector device coupled with a proximal end of the ultrasound catheter. In some embodiments, the method may further involve injecting dye into the blood vessel through the guidewire lumen. Alternatively, dye may be injected through a catheter via means other than a guidewire lumen.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
• FIG. 1 is a perspective view of a system including an ultrasound catheter device and ultrasound energy source according to an embodiment of the present invention;
• FIG. 1ais a side view of a mandrel and a catheter body, showing a method for making a catheter body according to an embodiment of the present invention;
• FIG. 1bis a cross-sectional side view of a distal end of a catheter body and an ultrasound transmission member within the body according to an embodiment of the present invention;
• FIG. 2 is a cross-sectional side view of a distal end of an ultrasound catheter device according to an embodiment of the present invention;
• FIG. 2ais a cross-sectional front view of an ultrasound catheter device from the perspective of the arrows labeled “a” inFIG. 2;
• FIG. 2bis a partial cut-away perspective view of an ultrasound transmission member with a friction reducing coating or jacket according to an embodiment of the present invention;
• FIG. 3 is a cross-sectional view of a distal end of an ultrasound catheter device according to another embodiment of the present invention;
• FIG. 4 is a cross-sectional view of a distal end of an ultrasound catheter device according to another embodiment of the present invention;
• FIG. 5 is a cross-sectional view of a distal end of an ultrasound catheter device according to another embodiment of the present invention;
• FIG. 5ais an exploded, cross-sectional, side view of a distal head, ultrasound transmission member and guidewire tube of an ultrasound catheter device according to an embodiment of the invention;
• FIG. 6 is a cross-sectional view of a distal end of an ultrasound catheter device according to another embodiment of the present invention;
• FIG. 7 is a cross-sectional view of a proximal connection assembly of an ultrasound catheter device according to an embodiment of the present invention;
• FIG. 7ais an exploded side view of a proximal connection assembly as inFIG. 7;
• FIG. 8 is a side view of a proximal end of an ultrasound catheter device coupled with a connector device according to an embodiment of the present invention; and
• FIG. 8ais an exploded, side view of a proximal end of an ultrasound catheter device and a connector device according to an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
• Ultrasound catheter devices and methods of the present invention may generally be used for treating occlusions in blood vessels. Catheter devices generally include a catheter body, an ultrasound energy transmission member disposed within the catheter body and a distal head coupled with the energy transmission member and disposed at or near the distal end of the catheter body. The ultrasound transmission member transmits ultrasound energy from an ultrasound transducer to the distal head, causing the head to vibrate and, thus, disrupt vascular occlusions.
• Some embodiments of an ultrasound catheter include at least one bend in the catheter body for enhancing positioning and/or advancement of the catheter in a blood vessel. A bend may facilitate, for example, placement or repositioning of the catheter in a branching vessel that branches off of a larger vessel. The bend in the catheter body is typically formed by heating the body while it is on a mandrel, but other suitable methods may be employed. The bend is formed when before the ultrasound transmission member is inserted into the catheter body, so as to reduce stress on the transmission member. In some embodiments, the transmission member bends somewhat when it is placed in the catheter body, but to a lesser degree than the catheter body is bent. Various locations for one or more bends n the catheter body, various angles for the bend(s) and the like may be used in various embodiments of the ultrasound catheter, as desired.
• Other embodiments of an ultrasound catheter may include various other improvements. For example, some embodiments include a sheath for maintaining a bend in the catheter when not in use. Some embodiments include a hydrophilic coating disposed over at least a portion of the external surface of the catheter body to enhance the lubricity of the body and facilitate advancement of the catheter through a blood vessel. Some embodiments include an over-the-wire guidewire tube to allow for enhanced injection of dye or other fluids near an occlusion and/or to facilitate guidewire changing during a procedure. Some embodiments include a distal head with an opening configured for enhanced attachment of the head to a guidewire tube disposed within the catheter body. In some embodiments, an ultrasound transducer coupled with the ultrasound catheter may be switched, via an actuator, between a pulsed ultrasound energy mode, a continuous ultrasound energy mode and/or other ultrasound energy modes, as desired. Some embodiments are sterilized via electron-beam sterilization. In any given embodiment, an ultrasound catheter may include any suitable combination of the features described above, as well as any other suitable features. These features will be described in further detail below in the form of examples, but these examples should in no way be interpreted to limit the scope of the invention as it is defined in the claims.
• Referring now toFIG. 1, one embodiment of anultrasound catheter system20 suitably includes anultrasound catheter10, a proximalend connector assembly12 coupled withcatheter10, anultrasound transducer14 coupled with the proximal end of aproximal connector assembly12, and anultrasound generator16 with apower cord17 and foot-actuated on/offswitch18, which is operatively coupled withultrasound transducer14 to provide ultrasonic energy totransducer14 and, thus, toultrasound catheter10. Generally,catheter10 includes an ultrasound transmission member, or wire (not shown), for transmitting energy from thetransducer14 to adistal head26 of the catheter. In some embodiments,catheter10 includes one ormore bends117 along its length for facilitating positioning and/or advancement ofcatheter10. Components ofsystem20 may be coupled via any suitable means, such as connectingwires11a,11bof any kind, wireless connections or the like.
• Proximal connector assembly12, described more fully below, may have aconnector device15, such as the W-connector that is shown, a Y-connector or the like.Connector device15 may include any suitable number of side-arms or ports, such as aguidewire arm19 for passage of a guidewire and aninfusion arm13 for infusing and/or withdrawing irrigation fluid, dye and/or the like. In other embodiments,catheter10 may be passed along a guidewire which accessescatheter10 via a side aperture rather thanconnector device15. For example, some embodiments include a rapid exchange guidewire lumen.Ultrasound catheters10 of the present invention may be used with any suitable proximal devices, such as anysuitable ultrasound transducer14,ultrasound generator16,connector assembly12, connector device(s)15 and/or the like. Therefore, exemplaryFIG. 1 and any following descriptions of proximal apparatus or systems for use withultrasound catheters10 should not be interpreted to limit the scope of the present invention as defined in the appended claims.
• In some embodiments,ultrasound generator16,ultrasound transducer14 or any other suitable component ofsystem20 may include one ormore actuators119 for switching between two or more modes or types of ultrasound energy transmission to an ultrasound transmission member ofcatheter10.Actuator119 may be used, for example, to switch between transmission of pulsed ultrasound signal and continuous ultrasound signal. Providing two or more different types of ultrasound signal may enhance disruption of a vascular occlusion, and in various embodiments, switching between types of signals may be performed in any order desired, as many times as desired, without stopping the transmission of ultrasound energy to make the switch and/or the like. Althoughactuator119 is pictured onultrasound generator16 inFIG. 1, it may be given any other location and configuration.
• Referring now toFIG. 2, a cross-sectional side view of the distal end of one embodiment ofultrasound catheter10 is shown. Generally,ultrasound catheter10 suitably includes anelongate catheter body22 with at least one hollowcatheter body lumen21. InFIG. 2,catheter body22 is shown having one lumen, but it may have any number of lumens in various embodiments. Disposed longitudinally withincatheter body lumen21 are anultrasound transmission member24 and ahollow guidewire tube28 forming aguidewire lumen29. Coupled with the distal ends ofultrasound transmission member24 andguidewire tube28 is adistal head26, positioned adjacent the distal end ofcatheter body22.
• Generally, the various coupled components described above may be coupled by any suitable means, such as adhesives, complementary threaded members, pressure fittings, and the like. For example,distal head26 may be coupled withultrasound transmission member24 andguidewire tube28 with any suitable adhesive substance. In one embodiment, for example,guidewire tube28 is coupled withdistal head26 by means of adhesive at multiple head/guide wire adhesive points30. In some embodiments,guidewire tube28 may also be coupled withcatheter body22 by adhesive or other means at one or more body/guidewire adhesive points32. As explained further below, some embodiments ofdistal head26 include one or more apertures for facilitating introduction of adhesive to coupledistal head26 toguidewire tube28.
• Catheter body22 is generally a flexible, tubular, elongate member, having any suitable diameter and length for reaching a vascular occlusion for treatment. In one embodiment, for example,catheter body22 preferably has an outer diameter of between about 0.5 mm and about 5.0 mm. In other embodiments, as in catheters intended for use in relatively small vessels,catheter body22 may have an outer diameter of between about 0.25 mm and about 2.5 mm.Catheter body22 may also have any suitable length. Some ultrasound catheters, for example, have a length in the range of about 150 cm. However, any other suitable length may be used without departing from the scope of the present invention. Examples of catheter bodies similar to those which may be used in the present invention are described in U.S. Pat. Nos. 5,267,954 and 5,989,208, which were previously incorporated herein by reference.
• As mentioned above, and with reference again toFIG. 1, in some embodiments ofultrasound catheter10catheter body22 includes one ormore bends117 along its length, for enhancing advancing and/orpositioning catheter10. For example, bend117 may facilitate advancement ofcatheter10 into a side-branch vessel of a larger vessel. Bend117 may be located at any suitable location alongcatheter10 and may have any suitable angle, relative to the longitudinal axis ofcatheter10, and any number ofbends117 having any number of configurations are contemplated within the scope of the invention. In some embodiments, for example,catheter body22 includes one bend, located between about 1 mm and about 20 mm from the distal end ofcatheter body22, and preferably between about 5 mm and about 15 mm from the distal end ofcatheter body22, and even more preferably between about 7 mm and about 10 mm from the distal end ofcatheter body22.
• Generally, and with reference now toFIG. 1a,in one embodiment of a method for makingcatheter10,bend117 incatheter body22 is formed by positioningcatheter body22 on amandrel114. In some embodiments,catheter body22 is formed onmandrel114, while in otherembodiments catheter body22 may be pre-formed and then placed onmandrel114 for formingbend117. In either case,mandrel114 may include or be coupled with astopper member120.Stopper member120 generally maintains a position ofcatheter body22 onmandrel114, to help ensure the formation ofbend117 in a desired location. In some embodiments,catheter body22 or material for makingcatheter body22 is placed onmandrel114 and is advanced until oneend118 of the material is stopped bystopper120. In some embodiments,catheter body22 is then heated in order to formbend117. Afterbend117 is formed,catheter body22 may be separated frommandrel114 and used as part ofcatheter10. This is but one example of a method for makingcatheter body22, and any suitable alternative methods including a mandrel for making a bend are contemplated within the scope of the invention.
• As previously mentioned,bend117 may have any suitable angle of deflection, relative to the longitudinal axis ofcatheter10. In some embodiments, for example, bend117 may have an angle of between about 20 degrees and about 50 degrees, and preferably an angle of between about 30 degrees and about 40 degrees. In some embodiments,catheter body22 may be formed having an angle that is greater, or more severe, than the final angle ofbend117 ofcatheter10. In other words, when an ultrasound transmission member is inserted into abent catheter body22, the ultrasound transmission member will typically bend slightly to conform to bend117, andcatheter body22 will straighten slightly to conform to the ultrasound transmission member. Thus,catheter body22 in some embodiments will be formed havingbend117 with an angle that is larger than the final angle that bend117 will have when the ultrasound transmission member is inserted. InFIG. 1a,for example, bend117 has an angle of approximately 90 degrees. Other embodiments may use any other suitable angles forbend117 ofcatheter body22 to arrive at a desired angle forbend117 when the ultrasound transmission member is inserted. For example, mandrels may have bends with angles of between about 20 degrees and about 90 degrees, or any other suitable angle, and may result in a catheter body having a bend of between about 15 degrees and about 80 degrees when an ultrasound transmission wire is inserted, or any other suitable angle.
• As just discussed, in one aspect of the invention, and with reference now toFIG. 1b,bend117 incatheter body22 has a more acute angle than a corresponding bend inultrasound transmission member24 inserted incatheter body22. This generally occurs becausecatheter body22 straightens somewhat whenultrasound transmission member24 is inserted andultrasound transmission member24 bends somewhat to conform to bend117 incatheter body22. In some embodiments, as shown,ultrasound transmission member24 is at least partially free to move within the lumen ofcatheter body22 so that it remains as straight as possible and is not forced to bend to the same extent thatcatheter body22 is bent. This less-bent configuration places less of a strain onultrasound transmission member24 during use, which in turn results in less wear and tear ofultrasound transmission member24 and a longer life of the device than would occur ifultrasound transmission member24 were more severely bent.
• Becauseultrasound transmission member24 may tend to straightenbend117 to a degree, some embodiments ofcatheter10 include a sheath, sleeve, cover or other shape-retention device for placement over at least a portion ofcatheter body22 whencatheter10 is not in use. For example, a shape-retention device may comprise a short, rigid, plastic sheath, having a bend in its length. When placed overcatheter body22 atbend117, the sheath may help retain the shape and angle ofbend117 during non-use. Whencatheter10 is to be used, the sheath is removed. Any suitable size, shape or material may be used for making such a shape-retention device and any such device falls within the scope of the present invention.
• In some embodiments,catheter10 includes a coating on the external or outward-facing surface ofcatheter body22. Coatings may alternatively be applied to any other surface or combination of surfaces ofcatheter10, as desired. A coating may be made of any suitable material, may have any suitable thickness and may cover any suitable length ofcatheter body22. In some embodiments, for example, the coating is made from one or more hydrophilic materials, which provide increased lubricity and decreased friction for the external surface ofcatheter body22, thus enhancing advancement and/or positioning ofcatheter10 in a blood vessel. For example, a hydrophilic coating oncatheter body22 may be similar to the coatings described in U.S. Pat. No. 5,538,512, entitled “Lubricious Flow Directed Catheter,” the full disclosure of which is hereby incorporated by reference. As described in U.S. Pat. No. 5,538,512, materials used for coatings may include, but are not limited to, polymers or oligomers of monomers selected from ethylene oxide and its higher homologs, including up to 6 carbon atoms; 2-vinyl pyridine; N-vinylpyrrolidone; polyethylene glycol acrylates such as mono-alkoxy polyethylene glycol mono(meth)acrylates, including mono-methoxy triethylene glycol mono(meth)acrylate, mono-methoxy tetraethylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate; other hydrophilic acrylates such as 2-hydroxyethylmethacrylate, glycerylmethacrylate; acrylic acid and its salts; acrylamide and acrylonitrile; acrylamidomethylpropane sulfonic acid and its salts, cellulose, cellulose derivatives such as methyl cellulose ethyl cellulose, carboxymethyl cellulose, cyanoethyl cellulose, cellulose acetate, polysaccharides such as amylose, pectin, amylopectin, alginic acid, and cross-linked heparin; maleic anhydride; aldehydes; etc. These monomers may be formed into homopolymers or block or random copolymers. The use of oligomers of these monomers in coating the catheter for further polymerization is also an alternative. Preferred monomers include ethylene oxide; 2-vinyl pyridine; N-vinylpyrrolidone and acrylic acid and its salts; acrylamide and acrylonitrile each polymerized (with or without substantial crosslinking) into homopolymers, or into random or block copolymers.
• Additionally, hydrophobic monomers may be included in the polymeric coating material in an amount up to about30% by weight of the resulting copolymer, so long as the hydrophilic nature of the resulting copolymer is not substantially compromised. Suitable monomers include ethylene, propylene, styrene, styrene derivatives, alkylmethacrylates, vinylchloride, vinylidenechloride, methacrylonitrile, and vinyl acetate. Preferred, because of their propensity for ease of linkage to the typical polymeric catheter substrates, are ethylene, propylene, styrene, and styrene derivatives.
• For further details regarding materials for coatings, methods for preparing and/or applying coatings, and/or the like, reference may be made to U.S. Pat. No. 5,538,512. Alternatively, any other suitable hydrophilic coating may be applied to an exterior surface and/or any other surface ofcatheter10, without departing from the scope of the present invention.
• Returning toFIG. 2, in many embodiments,ultrasound transmission member24 extends longitudinally throughcatheter body lumen21 to transmit ultrasonic energy fromultrasound transducer14, connected to the proximal end ofcatheter10, to the distal end ofcatheter10.Ultrasound transmission member24 may be formed of any material capable of effectively transmitting ultrasonic energy fromultrasound transducer14 to the distal end ofcatheter body22, including but not limited to metals such as titanium and nickel alloys.
• In accordance with one aspect of the invention, all or a portion ofultrasound transmission member24 may be formed of one or more materials which exhibit superelastic properties. Such material(s) should preferably exhibit superelasticity consistently within the range of temperatures normally encountered byultrasound transmission member24 during operation ofultrasound catheter apparatus10. Specifically, all or part of theultrasound transmission member24 may be formed of one or more metal alloys known as “shape memory alloys.”
• Use of supereleastic metal alloys in ultrasound transmission members is described in U.S. Pat. No. 5,267,954, previously incorporated by reference. Examples of superelastic metal alloys which may be used are described in detail in U.S. Pat. No. 4,665,906 (Jervis); U.S. Pat. No. 4,565,589 (Harrison); U.S. Pat. No. 4,505,767 (Quin); and U.S. Pat. No. 4,337,090 (Harrison), the entire disclosures of which are hereby incorporated by reference insofar as they describe the compositions, properties, chemistries and behavior of specific metal alloys which are superelastic within the temperature range at whichultrasound transmission member24 of the present invention operates, any and all of which superelastic metal alloys may be used to formultrasound transmission member24 of the present invention.
• In many embodiments,ultrasound transmission member24 includes one or more tapered regions along a portion of its length, towards its distal end. Such a tapered region23 decreases the distal rigidity ofultrasound transmission member24, thus amplifying ultrasound energy transmitted alongultrasound transmission member24 todistal head26. Tapered region23 typically divides thetransmission member24 between a proximal portion and a distal portion, which both typically have a larger cross-sectional diameter than tapered region23, as pictured inFIG. 2. A thicker distal portion, for example, may enhance stability of the connection betweenultrasound transmission member24 anddistal head26. Other embodiments are contemplated, however. For example, tapered region23 may be positioned at the extreme distal end oftransmission member24. In still other embodiments,ultrasound transmission member24 may include multiple tapered portions, widened portions and/or the like. Thus,ultrasound transmission member24 may be configured with any suitable length, combinations of diameters and tapers, or any other suitable shapes, sizes or configurations to advantageously transmit ultrasound energy fromtransducer14 todistal tip26.
• With reference now toFIG. 2b,in some embodimentsultrasound transmission member24 may include a low-friction coating25, jacket or similar covering on all or a portion of its outer surface.Coating25 may be disposed on the outer surface ofultrasound transmission member24 so as to completely coverultrasound transmission member24 along its entire length, or along a discrete region or regions thereof. Such coating orjacket25 may comprise a layer of low friction polymer material such as polytetrafluoroethylene (PTFE), TEFLON™ (available from Dupont, Inc., Wilmington, Del.) or other plastic materials such as polyethylene.Coating25 may be applied as a liquid and subsequently allowed to cure or harden on the surface ofultrasound transmission member24. Alternatively, coating25 may be in the form of an elongate tube, disposable over the outer surface ofultrasound transmission member24. Generally, coating25 serves to prevent or diminish friction between the outer surface ofultrasound transmission member24 and the adjacent structures ofcatheter10 or proximalend connector assembly12 through whichultrasound transmission member24 extends.
• In most embodiments,distal head26 is mounted on or otherwise coupled with the distal end ofultrasound transmission member24. In many embodiments, as shown inFIG. 2, distal tip includes aproximal region27 with an outer diameter configured to fit within the distal end ofcatheter body lumen21 and adistal region29 with a slightly larger diameter thanproximal region27. In many embodiments, all or a portion ofdistal region29 ofdistal head26 will have an outer diameter approximately the same as the outer diameter ofcatheter body22. Thus, in embodiments like the one pictured inFIG. 2, the distal end ofcatheter body22 overlaps at least a portion ofdistal head26. The amount of overlap may vary in different embodiments, so that in someembodiments catheter body22 may completely overlapdistal head26. This overlapping may enhance stability of the distal end ofcatheter10 anddistal head26 in particular.
• In another embodiment, as shown inFIG. 3,distal head34 is configured so that its proximal end abuts the distal end ofcatheter body22. In this embodiment,distal head26 is held in positionadjacent catheter body22 by its attachment toultrasound transmission member24 and/or guidewire tube28 and does not fit withincatheter body lumen21. Typically, in such an embodiment, all or a portion ofdistal head34 will have an outer diameter that is approximately equal in dimension to the outer diameter ofcatheter body22.
• As is evident fromdistal heads26 and34, shown inFIGS. 2 and 3, distal heads may have any suitable configuration, shape, and size suitable for ablating or otherwise disrupting occlusions. For example,distal head26,34 may have a shape that is bulbous, conical, cylindrical, circular, rectangular or the like. Similarly,distal head26,34 may have dimensions which allow it to fit wholly or partially within the distal end ofcatheter body lumen21 or may, alternatively, be disposed completely outsidecatheter body lumen21. Thus, the configuration ofdistal head26 may take any suitable form and should in no way be limited by the exemplary embodiments pictured inFIGS. 2 and 3 and described above or below.
• In some embodiments,distal head26 is not directly affixed to the distal end ofcatheter body22. Instead, in various embodiments, it is held in place by its attachment to eitherultrasound transmission member24,guidewire tube28, or both. In some embodiments,distal head26 may additionally be secured to the distal end ofcatheter body22 by fitting partially or wholly withincatheter body lumen21, as described above. In embodiments wheredistal head26 is not directly affixed to the distal end of catheter body,distal head26 will be able to move freely, relative to the distal end ofcatheter body22. Positioningdistal head26 in this way, without affixing it tocatheter body22, allows greater freedom of movement ofhead26, providing enhanced efficiency of ultrasound energy transmission and reduced stress toultrasound transmission member24.
• Distal head26 may be coupled indirectly withcatheter body22 at one or more points proximal to the distal end ofcatheter body22. In some embodiments, for example,distal head26 is indirectly coupled to thecatheter body22 viaguidewire tube28, as described further below. For example,distal head26 may be coupled withguidewire tube28, andguidewire tube28 may be coupled withcatheter body22 at a location within 1 cm of the distal end ofcatheter body22, at a location around 25 cm from the distal end ofcatheter body22, or at any other location or combination of locations. In other embodiments,distal head26 may be coupled withultrasound transmission member24, andultrasound transmission member24 may be coupled withcatheter body22 near its proximal end and/or at any other suitable location.
• In some embodiments,distal head26 is formed of radiodense material so as to be easily discernable by radiographic means. For example,distal head26 may be formed of a metal or metal alloy. Alternatively,distal head26 may be made of a polymer or ceramic material having one or more radiodense markers affixed to or located withindistal head26. In one embodiment, for example,distal head26 may be molded of plastic such as acrylonitrile-butadiene-styrene (ABS) and one or more metallic foil strips or other radiopaque markers may be affixed to such plasticdistal head26 in order to impart sufficient radiodensity to permitdistal head26 to be readily located by radiographic means. Additionally, in embodiments whereindistal tip26 is formed of molded plastic or other non-metallic material, a quantity of radiodense filler such as powdered bismuth or BaSO₄may be disposed within the plastic or other non-metallic material of whichdistal head26 is formed so as to impart enhanced radiodensity todistal head26.
• In some embodiments,guidewire tube28 is also disposed longitudinally withincatheter body lumen21, along all or a portion of the luminal length.Guidewire tube28 may also extend throughdistal head26, as shown inFIGS. 2 and 3, to allow a guidewire to pass through the distal end ofdistal head26. Alternatively,guidewire tube28 andguidewire lumen29 may be given any suitable configuration, length, diameter and the like suitable for passingcatheter10 along a guide wire to a location for treatment. For example, in some embodiments, a relativelyshort guidewire lumen29 may be formed near the distal end ofcatheter body22 to permit rapid exchange of catheters. In other embodiments,catheter10 may include an over-the-wire guidewire tube28 andguidewire lumen29 that extend along all or almost all of the length ofcatheter10. Such an over-the-wire configuration may be beneficial for providing means for a super-selective dye injection at a location near an occlusion, for facilitating one or more changes of guidewires during a procedure, for enhancing manipulation ofcatheter10 and/or the like. In some embodiments,guidewire tube28 may include micro-perforations or apertures along all or a portion of its length. The micro-perforations may allow, for example, passage of fluid into the guidewire lumen to provided lubrication to a guidewire. In some embodiments having over-the-wire guidewire tubes28,guidewire lumens29 may be accessed via aguidewire arm19 onconnector device15. Again,connector device15 may comprise a W-connector, a Y-connector or any other suitable device. Thus,catheters10 of the present invention are not limited to those includingguidewire tubes28 and orguidewire lumens29 as described byFIGS. 2 and 3, but may include any suitable guidewire lumens, tubes or the like.
• In some embodiments,guidewire tube28 is attached to bothdistal head26 andcatheter body22. As previously described, such attachment may be accomplished by any suitable means, such as by an adhesive substance. Generally,guidewire tube28 is attached within a portion ofdistal head26 at one or more adhesive points30. An outer wall ofguidewire tube28 also may be attached to an inner wall ofcatheter body22 at one or more guidewire tube/catheter body adhesive points32. For example, in some embodiments tube/catheter bodyadhesive point32 is located approximately 25 cm from the distal end ofcatheter body22. Other embodiments may include one tube/catheter body adhesive point at approximately 25 cm from the distal end ofcatheter body22 and another tube/catheter body adhesive point within approximately 1 cm of the distal end ofcatheter body22. Any suitable adhesive point or combination of multiple adhesive points is contemplated.
• Such attachment ofguidewire tube28 to bothdistal head26 andcatheter body22 helps to holddistal head26 in its position at the distal end ofcatheter body22. Attachment also helps limit unwanted transverse motion ofdistal head26 while allowing longitudinal motion due to tube elasticity. Adhesives used to attachguide wire tube28 todistal head26 andcatheter body22 may include, but are not limited to cyanoacrylate (eg. Loctite™, Loctite Corp., Ontario, CANADA or Dron Alpha™, Borden, Inc., Columbus, Ohio) or polyurethane (e.g. Dymax™, Dymax Engineering Adhesive, Torrington, Conn.) adhesives.
• In still other embodiments, a portion ofdistal head26 may be formed to extend laterally wider than the outer surface ofcatheter body22 andguidewire tube28 may be positioned on the outer surface ofcatheter body22. Such embodiments, whereinguidewire tube28 is positioned along the outer surface ofcatheter body22, are commonly referred to as “monorail” catheters, as opposed to “over-the-wire” catheters as described byFIGS. 2 and 3. In addition to over-the-wire embodiments and monorail embodiments,ultrasound catheter10 may also be configured as a combination or hybrid of over-the-wire and monorail embodiments. Specifically, such embodiments may include anultrasound catheter10 having aguidewire tube28 formed through a distal portion ofcatheter body22 only, with a guidewire entry/re-entry aperture being formed through a sidewall ofcatheter body22 to permit passage of a guidewire from the distal guidewire lumen of the catheter to a position outside the catheter body.
• With reference now toFIG. 2a,some embodiments ofultrasound catheter10 include one or morefluid outflow apertures36 indistal head26 to permit fluid flow out ofcatheter body lumen21. Other embodiments (not shown) may include one or more similar apertures at or near the distal end ofcatheter body22, either in addition to or in place ofapertures36 indistal head26.Outflow apertures36 facilitate continual or intermittent passage of irrigant liquid throughlumen21, for example by infusion intolumen21 via one or more side-arms11,13. Infusion of irrigant liquid throughlumen21, in proximity toultrasound transmission member24, may be used to control the temperature ofultrasound transmission member24 to prevent overheating during use and enhance the process of disruption of blood vessel obstruction. Irrigant liquids may include, but are not limited to, saline and the like.
• In some embodiments,guidewire tube28 andlumen29 are generally configured with an inner diameter slightly larger than the outer diameter of a guide wire along whichcatheter10 is passed. Such aguidewire tube28 may then be used as an alternative or additional means to allow fluid outflow throughdistal head26. In still other embodiments, one or more separate lumens having separate outflow apertures formed at or near the distal tip of the catheter may be formed for infusion of oxygenated perfusate, medicaments or other fluids into the blood vessel or other anatomical structure in which the catheter is positioned.
• Referring now toFIG. 4, some embodiments ofultrasound catheter10 include adistal sleeve72 which is coupled withcatheter body22 and which surrounds a portion ofultrasound transmission member24. Generally,distal sleeve72 comprises a hollow cylindrical member, made of any suitable material, such as but not limited to a polymer.Sleeve72 is coupled withcatheter body22 withinlumen21 at a location near the distal end ofcatheter body22.Sleeve72 may be coupled withbody22 via any reasonable means but will often by coupled via an adhesive at one or more adhesive points74, such as those described above for coupling other components ofcatheter10.
• By surrounding a portion ofultrasound transmission member24 and being coupled withcatheter body22,distal sleeve72 adds stability tocatheter10. Although it is not necessary for use ofcatheter10 and does not enhance the performance ofcatheter10, physicians often twist or torque catheters radially upon insertion and/or during use of a catheter. Such twisting motions may causeguidewire tube28 to kink and/or collapse astube28 moves in relation tocatheter body22 andtransmission member24. Placement ofdistal sleeve72 aroundtransmission member24 causes the components ofcatheter10 to move together whencatheter10 is twisted, thus avoiding kinking or collapsing ofguidewire tube28 and maintaining patency ofguide wire lumen29.
• Referring now toFIG. 5, another embodiment ofultrasound catheter10 includes adistal head sheath82.Distal head sheath82 is generally a cylindrical sheath that surrounds a portion ofdistal head26.Sheath82 is coupled withguidewire tube28 via an adhesive at anadhesive point84, which is accessed through asmall hole86 in a side portion ofdistal head26.Sheath82 may be made of any suitable material, but will typically be made of a polymer of the same or similar material with which guidewiretube28 is made. Securingsheath82 totube28 throughhole86 indistal head26, enhances the stability of the connection betweentube28 anddistal head26. Thus, there is less chance thatdistal head26 will break off fromcatheter10 and safety of the device is enhanced. Formingsheath82 andguidewire tube28 from the same or similar materials will allow for a secure connection between the two via an adhesive.
• With reference toFIG. 5a,an exploded side view ofdistal head26,ultrasound transmission member24 andguidewire tube28 is shown. In some embodiments,distal head26 may include anopening130, for facilitating the introduction of an adhesive.Opening130 is typically larger thanhole86, described above, but may have any suitable configuration. In some embodiments, for example, opening130 comprises a slot or similarly configured opening disposed around at least a portion of the circumference ofdistal head26. Any other suitable configuration is contemplated within the scope of the invention, but opening130 is generally configured to facilitate access through a portion ofdistal head26 to allow introduction of one or more adhesive substances. Such adhesives, for example, may directly coupledistal head26 toguidewire tube28, may couple sheath82 (not shown inFIG. 5a) toguidewire tube28 and/or the like. Enhanced adhesive coupling viaopening130 may enhance the useful life ofcatheter10 by preventing detachment ofdistal head28 fromguidewire tube28 or some other part ofcatheter10.
• With reference now toFIG. 6, yet another embodiment ofcatheter10 includes adistal head anchor94.Distal head anchor94 may comprise a wire or similar device made from metal, polymer or any other suitable material. Generally, a distal portion ofanchor94 is coupled withdistal head26 at anadhesive point96, and a proximal portion ofanchor94 is coupled withcatheter body22 at anadhesive point92 proximal to the extreme distal end ofcatheter body22. Therefore,distal head26 remains free-floating relative to the extreme distal end ofcatheter body22 but is anchored tocatheter body22 at a moreproximal location92. This anchoring helps ensure thatdistal head26 will not break off fromcatheter10 during use. Any suitable anchoring device may be used and is contemplated within the scope of the invention.
• Various types and designs of proximalend connector apparatus12,ultrasound transducers14,ultrasound generation devices16 and/or the like may be coupled withultrasound catheter10 for use ofcatheter10 to disrupt vascular occlusions. Detailed descriptions of such apparatus may be found, for example, in U.S. Pat. Nos. 5,267,954 and 5,380,274, invented by the inventor of the present invention and previously incorporated herein by reference. Therefore, theultrasound catheters apparatus20 and methods are not limited to use with anyparticular transducers14,ultrasound generators16,connector apparatus12 or the like.
• That being said, and with reference now toFIG. 7, one embodiment of proximalend connector apparatus12 suitably includes ahousing42 with a hollowinner bore44.Bore44 may have a uniform inner diameter along its length or, alternatively, may have multiple segments, such as aproximal segment47, amiddle segment45 and adistal segment49, each of which may surround one or more various components of proximalend connector apparatus12.
• Generally,proximal segment47 ofbore44 is configured to allow attachment toultrasound transducer56, viatransducer housing58 andtransducer thread54. As such,proximal segment47 includes a proximal portion ofsonic connector48, including asonic connector thread52 for connection withcomplementary transducer thread54.Proximal segment47 and/or theproximal end41 ofhousing42 may have any shape, diameter or configuration to allow coupling withtransducer housing58. As shown inFIG. 7,proximal segment47 may have an inner diameter of a size to allowtransducer housing58 to fit within it. Thus,transducer housing58 andproximal end41 may be coupled via a pressure fit. In other embodiments,transducer housing58 andproximal end41 may connect via complementary threads. In still other embodiments,transducer housing58 may fit around the outer diameter ofproximal end41. It should be apparent that any suitable configuration of proximal end may be used.
• Similarly,sonic connector thread52 may have any suitable size, shape and configuration for coupling with acomplementary transducer thread54. Such coupling may be achieved via complementary threads, snap-fit mechanism, or any other suitable means. Otherwise,sonic connector thread52 andsonic connector48 are generally configured to transmit ultrasound energy fromultrasound transducer56 toultrasound transmission member24. Apin50 is generally positioned withinsonic connector48 and is disposed betweenproximal segment47 andmiddle segment45 ofbore44.
• Middle segment45 ofbore44 typically surrounds a portion ofsonic connector48, which is coupled with the distal end ofultrasound transmission member24, and one or more sets ofabsorber members46, which surround a portion ofultrasound transmission member24 to reduce vibration ofmember24.Absorber members46 may include, for example, one or more O-rings.Sonic connector48 is coupled with the distal end ofultrasound transmission member24 by any suitable means, to transmit ultrasound energy tomember24 fromtransducer56.
• Absorber members46 are configured to circumferentially surroundultrasound transmission member24 in whole or in part to dampen transverse vibrations created by the transmission of ultrasound energy. The number, size and configuration ofabsorber members46 used may be determined based upon a desired level of dampening and any suitable configuration or combination may be used. Alternatively, other dampening structures may be used, rather thanabsorber members46, and thus the configuration ofproximal connector apparatus12 is not limited to the use of one or more sets ofabsorber members46.
• Distal segment49 ofbore44 typically surrounds a portion ofultrasound transmission member24 and may also contain one or more additional sets ofabsorber members46.Distal segment49 may also contain a portion ofconnector device15, which is coupled with thedistal end43 ofhousing42 of proximalend connector apparatus12. Again,connector device15 may comprise a Y-connector as inFIGS. 7 and 7a,a W-connector as inFIGS. 8 and 8a,or any other suitable connector device. Coupling ofconnector device15 withdistal end43 ofapparatus12 may be accomplished via complementary threads, pressure fitting, or any other suitable means. Acommon lumen45 ofconnector device15 allows passage ofultrasound transmission member24 and is in communication withcatheter body lumen21.
• Connector device15 may include aninfusion arm13 to allow for introduction and/or withdrawal of one or more fluids for irrigation, dye injection and/or the like.Connector device15 may further include additional arms, as described more fully below, for passage of a guide wire and/or passage of any other suitable structure or substance throughcatheter10. In some embodiments,infusion arm13 is in fluid communication withcommon lumen45 andcatheter body lumen21. In other embodiments,arm13 may have a lumen that communicates with a separate lumen inconnector device15 andcatheter body22.
• Generally, pressurized fluid such as an irrigant liquid may be infused throughinfusion arm13,common lumen45 andcatheter body lumen21 so that it flows out offluid outflow apertures36. The temperature and flow rate of such irrigant liquid may be specifically controlled to maintain the temperature ofultrasound transmission member24 at a desired temperature within its optimal working range and/or may enhance disruption of blood vessel occlusions. In particular, in embodiments of the invention whereinultrasound transmission member24 is formed of a metal alloy which exhibits optimal physical properties (e.g. super elasticity) within a specific range of temperatures, the temperature and flow rate of irrigant liquid infused throughinfusion arm13 may be specifically controlled to maintain the temperature ofultrasound transmission member24 within a range of temperatures at which it demonstrates its most desirable physical properties. For example, in embodiments of the invention whereultrasound transmission member24 is formed of a shape memory alloy which exhibits super elasticity when in its martensite state, but which loses super elasticity as it transitions to an austenite state, it will be desirable to adjust the temperature and flow rate of the irrigant liquid infused throughinfusion arm13 so as to maintain the shape memory alloy ofultrasound transmission member24 within a temperature range at which the alloy will remain in its martensite state and will not transition to an austenite state. The temperature at which such shape memory alloys transition from a martensite state to an austenite state is known as the “martensite transition temperature” of the material. Thus, in these embodiments, the fluid infused througharm13 will be at such temperature, and will be infused at such rate, as to maintain the shape memory alloy ofultrasound transmission member24 below its martensite transition temperature.
• Referring now toFIG. 7a,proximalend connector apparatus12 is shown in exploded side view. In this embodiment,sonic connector48 is held withinhousing42, by means ofdowel pin50. In other embodiments,dowel pin50 may not be included andsonic connector48 may be positioned within housing by other means. Otherwise,FIG. 4asimply demonstrates the various components previously described with reference toFIG. 4.
• With reference now toFIG. 8, in some embodiments a proximal end ofcatheter10 may be coupled withconnector device15 that comprises a W-connector.Connector device15 may includeinfusion arm13,guidewire arm19 and aguidewire port140 coupled withguidewire arm19. In some embodiments, acoupling device142 is used forcoupling connector device15 withcatheter body22. Coupling device may comprise, for example, a sheath, sleeve or any other suitable device.Connector device15 may also comprise any suitable connector, including any configuration of ports, lumen(s) and the like. In some embodiments, for example,guidewire arm19 will have an angle that is as slight as possible, relative to the longitudinal axis ofcatheter body22, so that only a minimal bending of a guidewire occurs when the guidewire is inserted intoguidewire arm19 andguidewire lumen28.
• FIG. 8ashows an exploded view ofconnector device15 and a proximal portion ofcatheter body22, as inFIG. 8. This view shows one embodiment of howcoupling device142 may be used to coupledcatheter body22 withconnector device15. In other embodiments, various alternative coupling means may be employed without departing from the scope of the present invention.
• In some embodiments,ultrasound catheter10, one or more components ofcatheter10 and/or one or more additional components ofultrasound system20 may be sterilized using an electron-beam sterilization technique. Electron-beam sterilization techniques are known. For example, one may refer to “Electron-Beam Systems for Medical Device Sterilization,” by L. R. Calhoun et al., at www.devicelink.com/mpb/archive/97/07/002.html, the entire contents of which is hereby incorporated by reference. Electron-beam radiation has not been applied for sterilization of devices such asultrasound catheter10 of the present invention. Such sterilization techniques may provide significant advantages by exposingcatheter10 to less stress than would occur with traditional sterilization methods.
• Although the invention has been described above with specific reference to various embodiments and examples, it should be understood that various additions, modifications, deletions and alterations may be made to such embodiments without departing from the spirit or scope of the invention. Accordingly, it is intended that all reasonably foreseeable additions, deletions, alterations and modifications be included within the scope of the invention as defined in the following claims.

Claims (12)

1. A method of making an ultrasound catheter for disrupting occlusions in blood vessels, the method comprising:

forming a bend in a catheter body;

subsequent to forming the bend, inserting an ultrasound transmission member into a lumen of the catheter body, such that the ultrasound transmission member is disposed at least partially within the formed bend of the catheter body; and

coupling a distal head with a distal portion of the ultrasound transmission member, such that the distal head is disposed completely outside of the catheter body.

2. A method as inclaim 1, wherein the process of inserting the ultrasound transmission member into the lumen of the catheter body reduces an angle of the formed bend of the catheter body.

3. A method as inclaim 1, wherein the process of inserting the ultrasound transmission member into the lumen of the catheter body causes the ultrasound transmission member to bend in the catheter body.

4. A method as inclaim 1, wherein the process of forming the bend in the catheter body comprises heating the catheter body.

5. A method of making an ultrasound catheter for disrupting occlusions in blood vessels, the method comprising:

forming a bend in a catheter body;

subsequent to forming the bend, inserting an ultrasound transmission member into a lumen of the catheter body, such that the ultrasound transmission member is disposed at least partially within the formed bend of the catheter body;

coupling the ultrasound transmission member with a sonic connector; and

coupling a distal head with a distal portion of the ultrasound transmission member, such that at least a portion of the distal head extends distally beyond a distal end of the catheter body.

6. A method as inclaim 5, wherein the process of inserting the ultrasound transmission member into the lumen of the catheter body reduces an angle of the formed bend of the catheter body.

7. A method as inclaim 5, wherein the process of inserting the ultrasound transmission member into the lumen of the catheter body causes the ultrasound transmission member to bend in the catheter body.

8. A method as inclaim 5, wherein the process of forming the bend in the catheter body comprises heating the catheter body.

9. A method of making an ultrasound catheter for disrupting occlusions in blood vessels, the method comprising:

forming a bend in a catheter body;

subsequent to forming the bend, inserting an ultrasound transmission member into a lumen of the catheter body, such that the ultrasound transmission member is disposed at least partially within the formed bend of the catheter body; and

coupling a distal head with a distal portion of the ultrasound transmission member, such that at least a portion of the distal head extends distally beyond a distal end of the catheter body.

10. A method as inclaim 9, wherein the process of inserting the ultrasound transmission member into the lumen of the catheter body reduces an angle of the formed bend of the catheter body.

11. A method as inclaim 9, wherein the process of inserting the ultrasound transmission member into the lumen of the catheter body causes the ultrasound transmission member to bend in the catheter body.

12. A method as inclaim 9, wherein the process of forming the bend in the catheter body comprises heating the catheter body.

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