Intravascular Devices

Abstract

An intravascular device for crossing an obstruction in a blood vessel includes an elongated intravascular element, such as a wire, an ultrasonic transducer mechanically coupled to the intravascular element for ultrasonically exciting a distal tip portion of the intravascular element to facilitate crossing of the obstruction, and one or more damping features mechanically coupled to the intravascular element at a location spaced from the distal tip portion to attenuate lateral displacement of the intravascular element.

Description

[Technical field]

[0001] The present invention relates to the treatment of ischemia by using ultrasonically activated wires or other elongated elements to cross obstructions within blood vessels and facilitate the introduction of subsequent therapeutic devices.

[0002] Prior Patent Applications The present invention develops concepts described in our international patent application published as WO 2020 / 094747, and in our unpublished UK patent application No. 2006665.0, the contents of which are incorporated herein by reference. [Background technology]

[0003] In endovascular procedures, an artery is selected and employed for use in gaining access to the vascular system based on the artery's ability to accommodate passage of the intended diagnostic or therapeutic device to the target site and the extent to which tissue and patient trauma can be minimized.

[0004] For example, in peripheral arterial or venous revascularization procedures, access is often achieved by surgical incision and puncture into the femoral, popliteal, tibial, and / or foot arteries, commonly known in medical terms as the Seldinger technique. Once access is achieved, an introducer wire and introducer sheath are inserted into the vessel and secured at the site. The sheath acts as a port for device introduction, withdrawal, and exchange, and functions to minimize abrasion of the arterial tissue. A guide catheter and guidewire are then introduced into the artery to provide additional protection and aid in device navigation to the target site, and delivery of therapy.

[0005] The guidewire is carefully pushed along the lumen of the vessel so as not to cause trauma to the vessel wall and navigated to the site of the obstruction. In a successful procedure, the guidewire is then pushed across or through the obstruction and held in place to act as a guide over which diagnostic or therapeutic devices, such as balloon catheters and stents, are tracked to the site of the blockage. Guidewires are used in other minimally invasive procedures to introduce other devices and instruments into vessels or other cavities within the body to allow for examination, diagnosis, and different types of treatment.

[0006] Guidewires are used, for example, for balloon angioplasty, gastrointestinal, urological, and gynecological procedures, all of which require a passageway to be created through an obstruction to facilitate the passage of larger, often more cumbersome devices to the site of the lesion, or to other targeted tissue distal to the lesion within the body.

[0007] Guidewires are important for therapeutic interventions and are manufactured from a variety of materials, most typically stainless steels and alloys including NiTi (nitinol), with many different designs. Their manufacture often involves modification of the chemical composition and microstructural morphology of the material, for example, by cold working the material while forming it into a wire, then machining the wire into various dimensional designs, and applying various heat treatments to produce the desired performance. As an example, a specific taper can be machined over the length of the wire to produce a differential degree of flexibility along the length of the wire. Thus, at its distal end, the wire will have sufficient flexibility to conform to the shape of the vessel, and strength to transmit forces to the tip ("tip stiffness") or to traverse through the lesion.

[0008] In conventional guidewires, the tapered segment is enclosed in a coil or jacket material that allows flexibility through the taper while still allowing force transmission through the coil to the distal tip of the wire. As explained below, such a coil or jacket material is not required in the wires of the present invention, since the force to excavate the lumen is transmitted by ultrasonic energy even if the wire is not coated or jacketed.

[0009] The length of wires used in endovascular procedures varies according to the distance they are likely to operate. As an example, wires of 750mm to up to 900mm in length are typically used in many peripheral applications where they may be introduced into the femoral or popliteal anatomy, or tracked to and through blockages in the ipsilateral iliac-femoral and infrapopliteal arteries. Wire lengths used in ipsilateral and coronary applications tend to be around 1200mm, 1500mm, or 1700mm in length. In fact, wire lengths that may be tracked antilaterally may be even longer, perhaps 2000mm to 2250mm or 2500mm or 3000mm. The most common wire lengths on the market are 1750mm, 1950mm, and 3000mm.

[0010] In many instances, extension wires may be used to facilitate the deployment of a particular treatment device. In this instance, the proximal end of the wire may require certain features.

[0011] Many conventional intravascular wires are passive mechanical devices with no active parts. Passive wires transmit nothing but energy applied by the clinician. They are manipulated by pushing, pulling and torquing their proximal ends to navigate to the site of the occlusion and then push through or around the occlusion. They come in a variety of configurations and designs to facilitate access and crossing of lesions in different anatomies and for different devices. However, very often the occlusion is too difficult for conventional wires to cross. These passive wires are limited when attempting to cross a nearly or completely occluded occlusion, where the guidewire does not function as intended or may be heavily calcified. In situations where passive wires are tracked down around the occlusion, for example in subintimal situations, such wires are often unsuccessful in re-entering the true lumen.

[0012] The present invention relates to the use of ultrasonic vibrations transmitted along a wire to cross an occlusion. Transmission of ultrasonic vibrations along small diameter catheters and assemblies is disclosed in U.S. Pat. No. 3,433,226. U.S. Pat. No. 5,971,949 describes the transmission of ultrasonic energy through waveguides of different configurations and tip shapes. U.S. Pat. No. 5,427,118 describes an ultrasonic guidewire system but does not discuss in detail the proximal shape of the wire or how it facilitates subsequent devices via the over-the-wire method.

[0013] Many current single transducer systems are not ultrasonically activated guidewires, but instead are ultrasonically activated catheters that include a wire member for agitating and cauterizing material. U.S. Patent Nos. 6,855,123 and 4,979,939 describe such systems. These catheters themselves require separate passive guidewires to help them navigate, and are therefore tools to facilitate separate guidewires crossing blockages. U.S. Patent No. 9,629,643 shows systems with various distal tip configurations, but all require separate guidewires for access.

[0014] These devices are directed to delivering alternative methods of revascularization and are often described as atherectomy devices, crossing devices, or vessel preparation devices. With few exceptions, they are not considered the same as crossing the lesion for the purpose of functioning as a device delivery system. In the present technology, these ultrasound and recanalization wire devices provide or affect atherectomy by enhancing revascularization and debulking the lesion by removing the plaque that forms the lesion.

[0015] In early, later, and current designs, ultrasound generator systems have become bulky due to the acoustics used, producing multiple frequencies and being large units scaled to control the pulse waves. Also, considerations of practical utility mean that known systems generally include separate elements. For example, many systems are designed with the signal generator housed in a separate unit from the transducer, and some are mounted on large trolley units, consoles, or stands that take up significant space in the clinical environment. U.S. Pat. No. 6,450,975, U.S. Pat. App. Pub. No. 2008 / 0228111, and U.S. Pat. No. 9,282,984 all describe such systems.

[0016] Ultrasound-activated catheter and wire systems have been considered in the past as a method of atherectomy and to prepare vessels for angioplasty treatment. Several products have been commercially available in the past, some remain on the market, and several new systems have recently come onto the market. Such catheter and wire systems often include an ultrasound generator and an ultrasound transducer. The ultrasound generator converts a mains power source into an ultrasonic waveform defined by its voltage amplitude, current, and frequency. The ultrasound transducer, and often an amplifying horn, converts the electrical energy into high frequency mechanical vibrations defined by the frequency and amplitude of the vibrations.

[0017] A small diameter wire waveguide is coupled at its proximal end to a transducer, either directly or through an optional horn, which transmits its mechanical vibrations to the distal tip of the wire, causing the distal tip of the wire to vibrate at a desired amplitude and frequency, intended to excavate material and ultimately facilitate revascularization or recanalization of vasculature and anatomical structures throughout the body. Tissue and material near the distal tip is affected by the ultrasonic movement of the tip in combination with its direct mechanical ablation, ablation and cavitation from the pressure wave component, and acoustic streaming that removes the ablated material from the zone around the tip.

[0018] In known intravascular wire systems activated by ultrasound, the proximal end of the guidewire is connected to a transducer. In our patent application published as WO 2020 / 094747, the wire not only travels through the transducer and extends distally therefrom, but also proximally. This allows the user to couple the transducer to the wire at any desired location and adjust the total length of the distal portion of the wire without having to cut it. The adjustable total length of the distal portion of the wire can be very useful for practical purposes, for example, to match the expected length of the path the wire tip needs to travel inside the patient's body. Also, control of the wire is enhanced in holding its placement in place within the lumen of the vessel while adjusting or reconnecting the activation source. Furthermore, the adjustable distal portion of the wire length helps to achieve and optimize resonance at the distal tip at any desired frequency.

[0019] When exciting the wire using ultrasonic energy, it is desirable to maximize the displacement amplitude at the distal tip of the wire to excavate the lesion. Conversely, for a guidewire extending proximally from the transducer, it is desirable to minimize displacement or movement of that proximal portion of the wire, which is outside the patient's body and can, in fact, hang freely from the proximal side of the activation unit. [Prior art documents] [Patent documents]

[0020] [Patent Document 1] U.S. Pat. No. 3,433,226 [Patent Document 2] U.S. Pat. No. 5,971,949 [Patent Document 3] U.S. Pat. No. 5,427,118 [Patent Document 4] U.S. Patent No. 6,855,123 [Patent Document 5] U.S. Pat. No. 4,979,939 [Patent Document 6] U.S. Patent No. 9,629,643 [Patent Document 7] U.S. Patent No. 6,450,975, [Patent Document 8] US Patent Application Publication No. 2008 / 0228111 [Patent Document 9] U.S. Patent No. 9,282,984 [Patent Document 10] International Publication No. 2020 / 094747 Summary of the Invention [Problem to be solved by the invention]

[0021] It is an object of the present invention to address one or more of the shortcomings associated with the prior art. [Means for solving the problem]

[0022] Summary of the Invention To this end, an intravascular device for traversing an obstacle within a blood vessel is provided. The intravascular device includes an elongated intravascular wire, an ultrasonic transducer, and one or more dampening features. The ultrasonic transducer is mechanically coupled to or in contact with the elongated intravascular wire to ultrasonically excite a distal tip thereof to facilitate traversing the obstacle. The one or more dampening features are mechanically coupled to the elongated intravascular wire to attenuate lateral displacement of the elongated intravascular wire at a particular location away from the distal tip. For example, dampening can be applied or induced proximal to the coupling to the transducer to attenuate proximal wave transmission and dampen lateral displacement of a portion of the wire that remains outside the vascular system distal to the coupling.

[0023] With the intravascular device according to the invention, it is possible to maximize the displacement amplitude at the distal tip of the wire in an energy efficient manner. For optimal efficiency, it is important that the majority of the power provided by the transducer is transferred to the distal tip by longitudinal wave motion through the wire. Thus, any loss of energy due to lateral vibration of the wire is minimized. With the dampening feature according to the invention, such lateral displacement is reduced, improving the energy efficiency of the intravascular device. Resistance to wire breakage is also improved.

[0024] In one embodiment of the intravascular device according to the invention, one or more restraining features are mechanically coupled to the elongated intravascular wire to attenuate lateral displacement of the elongated intravascular wire at one or more locations between the ultrasound transducer and the distal tip. When attempting to improve coupling to longitudinal displacement, limit lateral displacement, and improve the life of the wire, it has been found that restraining lateral motion of the distal portion of the intravascular wire, i.e., extending distally from where the wire is coupled to the transducer, provides the best results. A complicating factor in this is that the majority of the distal portion is inserted within the patient's body. However, as described below, the inventors have found various ways to achieve the desired restraint of the wire near the transducer coupling point where the distal section of the wire emerges without compromising, and indeed enhancing, the functionality of the device.

[0025] In a preferred embodiment, the ultrasound transducer is contained within a transducer housing. At least some of the suppression features can be provided within or on the transducer housing. Other suppression features can be mechanically coupled to the elongated intravascular wire outside of the transducer housing. There can be selective suppression at discrete suppression locations along the length of the wire.

[0026] In a preferred embodiment, the ultrasound transducer is coupled to an elongated intravascular wire such that the elongated intravascular wire extends proximally and distally from the ultrasound transducer. In such an embodiment, one or more dampening features can be mechanically coupled to the elongated intravascular wire to attenuate lateral and / or longitudinal displacement of the elongated intravascular wire at one or more locations proximal to the ultrasound transducer.

[0027] By constraining longitudinal and lateral movement of the proximal portion of the intravascular wire, such constraining features minimize displacement or movement of the end of the wire that is outside the patient's body and may actually hang freely proximal to the activation unit. Reducing or even avoiding such undesirable lateral movement of the proximal wire portion is important to ensure user safety and to avoid damage to expensive and sensitive equipment, including the wire itself.

[0028] More generally, the invention provides a device that allows selective or preferential control of the activation of a wire in any direction. A wire is an example of an elongated intravascular element that can be used as a waveguide or wave delivery system. For example, the element can be a hybrid of a wire and a catheter. In particular, the proximal portion of the element, e.g., about one meter of the element from the proximal end, may have a wire that is coated similar to a catheter or coating, while the distal portion of the element extending toward the distal end may be an uncoated wire. The wire or other element of the invention may be an internal component of an overall wave delivery system.

[0029] A number of specific embodiments of the above mentioned distal and proximal restraining features, particularly restraining both proximal to the transducer and distal to the transducer near the coupling location, are described below with reference to the figures. Some types of restraining features are provided inside the transducer housing, while other types of restraining features are provided along the wire portion on the outside of the housing. Some restraining features are primarily suited to restraining lateral movement of the distal or proximal wire portion, whereas other restraining features can be used at both ends or both sides of the coupling between the wire and the transducer. There can be continuous restraining or selective, graduated, or intermittent restraining along the wire. Restraining can also be achieved by adding weight to the wire at one or more discrete locations. [Brief description of the drawings]

[0030] Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings in which: [Figure 1] 1 is a schematic perspective view of an ultrasound wire system according to the present invention; [Diagram 2] FIG. 2 is a schematic diagram of a longitudinal section of the ultrasound activation unit shown in FIG. 1. [Diagram 3] 2 but shows an acoustic horn coupled to a transducer within the housing of the unit. [Figure 4] 2 but showing the lateral exit of the guidewire from the transducer of the unit. [Diagram 5] 4, but showing an acoustic horn coupled to a transducer within the housing of the unit. [Figure 6] FIG. 2 is a schematic diagram of a longitudinal section of a variation of the ultrasonic activation unit shown in FIG. 1, operable for pneumatically actuated clamping. [Figure 7] FIG. 1 is a schematic diagram of a longitudinal cross section of an ultrasonic activation unit of the present invention, in which an ultrasonic-to-wire connector and coupling mechanism includes a collet and a spring-loaded cap for applying torque. [Figure 8] 8 illustrates an alternative configuration of the distal restrainer shown in FIG. 7. [Figure 9] 1 shows a single tapered collet inside a recess distal to the transducer, with proximal and distal restraints. [Figure 10] Shown is a double tapered collet inside the recess distal to the transducer, with a proximal restraint. [Figure 11] FIG. 13 is a longitudinal cross-sectional view of a handheld ultrasonic activation unit showing internal features within the housing for restraining the proximal wire. [Figure 12] FIG. 13 is a longitudinal cross-sectional view of a handheld ultrasonic activation unit including a medium for counteracting the activity of the proximal wire. [Figure 13] FIG. 13 is an enlarged view of a detail of FIG. 12. [Figure 14] FIG. 13 is an end view of a cam arrangement for engaging and restraining a wire. [Figure 15] FIG. 1 is a longitudinal cross-sectional view of a handheld ultrasonic activation unit with a push button wire restraint mechanism. [Figure 16a] FIG. 1 is a longitudinal cross-sectional view of a handheld ultrasonic activation unit with a helical wire restraint mechanism. [Figure 16b] FIG. 16b is a cross-sectional view of the handheld ultrasonic activation unit of FIG. 16a. [Figure 17] FIG. 13 is a longitudinal cross-sectional view of a handheld ultrasonic activation unit with an alternative wire restraint mechanism. [Figure 18] FIG. 13 is a longitudinal cross-sectional view of a handheld ultrasonic activation unit with an alternative wire restraint mechanism that can be removed as needed to allow repositioning of the wire. [Figure 19] FIG. 13 is a side view of a longitudinally split collet arranged to suppress proximal excitation of the wire. [Figure 20] FIG. 1 is a schematic diagram of a wire showing an example of an attachment location marker. [Figure 21]FIG. 1 is a perspective view of an ultrasonic activation unit of the present invention fitted with a removable distal safety and strain relief feature. [Figure 22] FIG. 22 is a longitudinal cross-sectional view of the arrangement of FIG. 21 in use during a procedure. [Figure 23] FIG. 22 is a perspective view showing the arrangement of FIG. 21 for use during a procedure. [Figure 24] FIG. 22 is another perspective view showing the arrangement of FIG. 21 for use during a procedure. [Diagram 25] FIG. 2 is a schematic diagram of a protective sheath for use with the present invention. [Figure 26] 1 shows an ultrasound activation unit with proximal inhibition features. [Figure 27] 13 illustrates another ultrasonic activation unit with a proximal inhibition feature. [Figure 28] 13 illustrates yet another ultrasonic activation unit with a proximal inhibition feature. [Figure 29] 1 shows an ultrasonic activation unit with proximal and distal twist locks for clamping the intravascular wire at two points. [Figure 30a] 1 shows three configurations of protrusions for reducing lateral movement of an intravascular wire. [Figure 30b] 1 shows three configurations of protrusions for reducing lateral movement of an intravascular wire. [Figure 30c] 1 shows three configurations of protrusions for reducing lateral movement of an intravascular wire. [Diagram 31] 13 shows a further example of a proximal suppressor of an ultrasound activation unit. [Diagram 32] 13 illustrates yet another ultrasonic activation unit with a proximal inhibition feature. [Diagram 33] 1 shows an ultrasound activation unit with distal suppression features. [Figure 34a] Three examples of motion restraining wire sheaths are shown that provide selective or intermittent restraint via selective or intermittent covering or surrounding of the wire. [Figure 34b]Three examples of motion restraining wire sheaths are shown that provide selective or intermittent restraint via selective or intermittent covering or surrounding of the wire. [Fig. 34c] Three examples of motion restraining wire sheaths are shown that provide selective or intermittent restraint via selective or intermittent covering or surrounding of the wire. [Figure 35a] 13 shows a modified example of the distal restraining mechanism. [Figure 35b] 13 shows a modified example of the distal restraining mechanism. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Figure 1 of the drawings shows the overall configuration of a system according to the invention and illustrates some of the main components of such a system. This example features a handheld ultrasonic activation unit 2 through which a flexible transmission member, in the form of an intravascular wire 4, extends in a centrally aligned manner.

[0032] The wire 4 can be inserted and traversed within the patient's vasculature to bring its distal end to the location of the lesion. Upon encountering a complex lesion that resists the wire 4 traversing the patient's vasculature, the activation unit 2 can couple to the wire 4 at a suitable longitudinal location. When activated, the activation unit 2 transmits ultrasonic vibrations to and along the wire 4, enhancing the ability of the wire 4 to traverse the lesion via cauterization and other mechanisms. The wire 4 can thereby serve as a traversal wire to traverse through an obstruction within a blood vessel and then remain in place to serve as a guidewire for delivery of a subsequent therapeutic device to treat the lesion.

[0033] Typically, the length of the wire 4 can be, for example, greater than 2 m and up to 3 m. For example, accessing a lesion in or through the foot may require the wire to travel a distance of typically 1200 mm to 2000 mm within the vascular system depending on whether an ipsilateral, antilateral, or radial approach is selected. In this regard, the wire 4, which tapers distally to a fine wire at its tip, can navigate into the pedicle arteries and around the arch of the foot between the dorsal and plantar arteries. However, the present invention is not limited to foot or other peripheral applications, but can be used, for example, in coronary applications, where the ability of the wire 4 to navigate and drill within tortuous, small diameter arteries is also beneficial.

[0034] The diameter of the distal section of the wire 4 will determine the flexibility of the wire 4 and the ability of the wire to easily conform to the shape of the anatomy it is intended to pass through. Thus, for example, in a tortuous (foot or coronary) anatomy, a distal section of appropriate length, for example, 0.005" to 0.007" in diameter, will combine appropriate flexibility with the ability of the particular Nitinol to excavate occlusive materials.

[0035] The activation unit 2 includes a user control 6 and optionally a display. The activation unit 2 further includes a distal manual toggle 8 that the user can rotate about a central longitudinal axis of the unit 2 and the wire 4. In particular, the activation unit 2 can be slid over the wire 4 and can be coupled to the wire 4 at multiple longitudinally spaced locations by applying torque to rotate the toggle 8. To effect the coupling, the toggle 8 acts on a coupling, such as a collet, within the activation unit 2 that surrounds and is coaxial with the wire 4, as shown in subsequent figures. When the toggle 8 is tightened, the collet grips the wire 4 and transmits ultrasonic energy from an integrated ultrasonic transducer within the activation unit 2, optionally via an amplifier horn that is coupled to or integral with the transducer. The wire 4 can be directly coupled to the transducer in some embodiments, in which case the horn can be omitted.

[0036] The toggle 8 reversibly releases the activation unit 2 from the wire 4. Provision is thereby made to exchange wires 4 of different dimensions, configurations or materials for different purposes. There is also the possibility to exchange the transducer or horn in the activation unit 2.

[0037] FIG. 1 shows a separate arrangement in which the ultrasonic signal generator 10 is separate from the activation unit 2. In this example, the ultrasonic signal generator 10 is connected to the activation unit 2 by a connector cable 12. In an alternative arrangement, the ultrasonic signal generator 10 can be integrated into the housing of the activation unit 2. The example shown in FIG. 1 has the ultrasonic signal generator 10 powered externally and therefore includes a power cable 14 connecting to an external power source. In an alternative embodiment, it may be powered by an internal battery, which can be integrated, for example, in the ultrasonic signal generator unit 10 or in the activation unit 2.

[0038] In general, the system components are preferably portable, and more preferably handheld. They may be wireless, rechargeable, reusable, and recyclable. Any external cables 12, 14 for carrying power or signals may be coupled via slip rings to allow free rotation of the cables 12, 14 and avoid entanglement with the wires 4.

[0039] Turning now to Figures 2 to 5, these figures show various arrangements of the activation unit in longitudinal cross section. Like numerals are used for like features. In each of these examples, the activation unit 2 is externally powered, optionally with an ultrasonic signal via cable 12, although as mentioned above a self-contained battery powered variant is also possible.

[0040] FIG. 2 shows that the housing 18 of the unit 2 houses an ultrasonic transducer 20, which is threaded by a central port or lumen 22 to allow passage of the wire 4 through. The distal portion of the transducer 20 has a threaded section to allow engagement of a collet 24. Various collet concepts will be described later. The wire 4 extends through the entire length of the transducer 20, emerging proximally from the housing 18 in this example. A compressible damping ring 45 is provided proximal to the collet 24 to help minimize movement of the proximal portion of the wire 4. This damping ring 45 can be made of an elastic material (i.e., compressible and resilient), such as a polymer or polymer blend.

[0041] 3 illustrates another embodiment of the invention in which an acoustic horn 26 is attached to the distal face of the transducer 20. Acoustic horns such as these can be used to amplify the displacement from the distal face of the transducer 20. To this end, the horn 26 can taper distally in a continuous tapered configuration, or in a stepped configuration, as shown in the figure.

[0042] 3, the wire 4 is coupled via a collet 24 to the distal end or face of a horn 26. The horn 26 has a central lumen 22 or channel that aligns with and communicates with a lumen 22 in the ultrasound transducer 20. This allows the wire 4 to travel through the center of the horn 26 and transducer 20 along their common longitudinal axis.

[0043] Figure 4 shows a similar configuration to Figure 2, but in this case the wire 4 does not traverse through the center of the length of the ultrasound transducer 20. Instead, the wire 4 emerges laterally from the transducer 20 at a location between the piezoelectric ceramic stack 28 and the distal end or front mass 30 of the transducer 20 where the collet 24 is located.

[0044] Similarly, Figure 5 shows a similar configuration to Figure 3, but in this case the wire 4 does not traverse through the entire center of the ultrasonic transducer 20 and horn 26, but instead emerges laterally from the horn 26 at a location along the length of the horn 26 between the collet 24 and the distal face of the transducer 20. Thus, in Figures 4 and 5, the wire 4 deviates at an acute angle from the central longitudinal axis of the transducer 20 or horn 26 to exit laterally through the side of the transducer 20 or horn 26.

[0045] It should be noted that the arrangement of the present invention illustrated in Figures 2-5 differs from the prior art which uses an electric motor and a cam or spindle to convert rotary motion to linear motion to drive the vibration of a wire. Instead, the present invention uses an ultrasonic transducer 20 that includes a piezoelectric ceramic stack 28 and front and rear (or distal and proximal) masses. It employs the piezoelectric effect of the piezoelectric ceramic stack 28, where electrical energy is converted into high frequency axial linear vibration.

[0046] Additionally, unlike the prior art, the present invention allows the wire 4 to extend through the activation unit 2 and further be coupled to the distal end of the transducer 20, which expression includes an acoustic horn 26 that can optionally be coupled to the distal end of the transducer 20. The prior art does not accommodate allowing the wire to travel through at least the center of the distal end of the transducer when using an ultrasonic transducer. This feature of the present invention allows the activation unit 2 to be moved along the wire 4 and then coupled to transmit ultrasonic energy to the wire 4 at any of a number of locations spaced longitudinally along the wire 4.

[0047] 6 shows an activation unit 2, similar to the arrangement shown in FIG. 2, housing an ultrasonic transducer 20 with a central lumen 22 that allows for a straight through passage of the wire 4. In this case, however, the distal end of the transducer includes a pneumatic micro-chuck 32 that allows for engagement and release of the wire 4. The chuck 32 has diagonally spaced jaws, e.g., three or four jaws, that act on the wire 4 directly or via a collet 24 to clamp and release the wire 4 with a constant force.

[0048] Specifically, pneumatic activation of the chuck system compresses the chuck 32 onto the collet 24 disposed on or around the wire 4 to clamp the wire 4 with the pressure required to couple ultrasonic energy emanating from the transducer 20. Air pressure can be used to regulate the force applied by the chuck 32 to apply a constant required gripping force. Solenoids can be used to control capture and release of the wire 4, allowing the wire 4 to be moved or indexed longitudinally relative to the activation unit 2. This allows the wire 4 to be locked in place, overcoming the potential for fluctuating regulated air pressure.

[0049] In this example, a compressed air delivery port in communication with the chuck branches to define a secondary channel that provides a cooling air flow for cooling the activation mechanism 2 in general, and the bond area in particular.

[0050] It will be apparent that the principles of the pneumatic chuck 32 shown in Figure 6 may also be applied to arrangements employing an acoustic horn 26, similar to those shown in Figures 3-5, or in which the wire 4 exits laterally from the transducer 20 or horn 26. Note that for simplicity, references to the transducer 20 in this description may refer to the front or distal mass 30 of the transducer 20, or to the acoustic horn 26 being attached to the distal face of the transducer, and thus effectively becoming an integral part of the transducer 20.

[0051] Turning now to Figure 7 of the drawings, the housing 18 of the activation unit 2 is tubular and coaxially surrounds the front mass of the ultrasound transducer 20. The transducer 20 extends distally to near the distal end of the housing. In this example, the wire 4 extends axially along and through the transducer 20 via a central lumen 22, although the wire 4 could alternatively exit the housing 18 laterally as in Figures 4 and 5. Also, as in Figures 3 and 5, the front mass of the transducer 20 could be replaced by an acoustic horn 26.

[0052] The distal end of the housing 18 is closed by a toggle 8. The toggle 8 can rotate about a central longitudinal axis of the wire 4 and can also urge axially in a proximal direction against the distal bias of a spring 42 within the housing 18. The spring 42 can be a separate spring, such as a coil spring, or can be formed by a resilient formation, such as a helical member, attached to or integral with the housing 18 and / or the toggle 8. The toggle 8 is shown here in a distal position biased by the spring 42 spaced from the distal end of the transducer 20. More generally, the rotational and / or axial movement of the toggle 8 relative to the collet 24 can be induced or determined by a cam or spline formation.

[0053] A distally-opening, proximally-tapered socket or recess 44 at the distal end of transducer 20 receives a proximally-tapered collet 24 which is aligned with lumen 22 of transducer 20 and surrounds wire 4. Collet 24 has external threads which engage complementary internal threads in the distal recess of transducer 20.

[0054] Collet 24 is threaded into a recess in transducer 20 and then released by a user manipulating toggle 8. Specifically, the user first presses toggle 8 axially in a proximal direction to engage collet 24, and then rotates toggle 8 to advance collet 24 proximally along the threads in the recess, thus coupling transducer 20 with wire 4 via collet 24. When released by the user, toggle 8 springs distally out of collet 24 and, as a result, does not impede the transmission of ultrasonic energy from transducer 20 along wire 4.

[0055] To this end, a distal end portion of collet 24 protrudes distally from the distal end of transducer 20. When toggle 8 is pushed proximally against the bias of spring 42, toggle 8 engages the protruding distal end portion of collet 24 via a complementary interface formation. This engagement between toggle 8 and collet 24 allows torque to be transferred from toggle 8 to collet 24, thus advancing collet 24 proximally along the threads in the recess.

[0056] In this manner, when the collet 24 is threaded into the recess of the transducer 20, the complementary proximal tapered surface and recess of the collet cause the collet 24 to clamp tightly against the wire 4, distributing the clamping force along the wire 4 and avoiding point loading. This clamping method in conjunction with proper selection of the collet 24 material allows for excellent fit and ultrasonic transmission. The entire transducer 20 and collet 24 assembly is tuned for optimal resonant response.

[0057] When the wire 4 can be released from the activation unit 2, the collet 24 can be released by again pressing the toggle 8 proximally to engage the collet 24, and then rotating the toggle 8 in the opposite direction to pull the collet 24 distally back along the threads in the recess in the transducer 20. This relaxes the grip of the collet 24 on the wire 4, allowing the wire 4 to be withdrawn from the activation unit 2.

[0058] Optionally, as shown in FIG. 7, an internal suppressor 46 may be disposed at the proximal end of the collet 24. This suppressor 46 is similar in function to the damping ring 45 shown in FIGS. 2-5. In this example, the internal suppressor 46 is an annular collar of superelastic material that surrounds the wire 4 within the lumen 22 of the transducer 20. When the collet 24 is threaded into the distal recess of the transducer 20, the suppressor 46 is axially compressed and radially thickened, thus deforming around and pressing against the wire 4. The suppressor 46 thereby suppresses or attenuates the proximal transmission of ultrasonic energy imparted by the transducer 20 through the collet 24 to the wire 4.

[0059] FIG. 7 also shows an optional internal protective sleeve 48 disposed about the wire 4 within the lumen 22. The sleeve 48 is made of a low friction, highly wear resistant material and centers the wire 4 within the lumen 22 and shields the wire 4 from the surrounding walls of the transducer 20. The sleeve 48, like the suppressor 46, is preferably made of a material that has a suppressing or attenuating effect on the proximal transmission of ultrasonic energy imparted to the wire 4 by the transducer 20. Similar sleeves 49, 51 can be disposed in the distal portion of the collet 24 and between the toggle 8 and the wire 4 to center and support the wire 4 as it emerges distally from the collet 24. The sleeve 51 between the toggle 8 and the wire 4 can extend partially distally therefrom. Like the sleeve 48 disposed between the transducer 20 and the wire 4, the sleeves 49, 51 disposed in the collet 24 and the toggle 8 are preferably configured to have a suppressing or attenuating effect on the proximal transmission of ultrasonic energy imparted to the wire 4.

[0060] 7 is a torque limiter 50 in the toggle 8 that acts between the exterior of the toggle 8 and the collet 24 when the toggle 8 engages the collet 24. This torque limiter 50 causes the toggle 8 to slip relative to the collet 24, for example, by deformation of a flexible or elastic interface formation of the toggle 8 and / or collet 24, if the torque applied to the toggle 8 by a user exceeds a predetermined limit. This prevents the user from over-tightening the collet 24 by applying too much torque to the toggle 8, which could otherwise cause the collet 24 to compress too much and thus become over-stressed and risk breaking the wire 4.

[0061] 7 also includes a strain relief feature, exemplified here by a distal taper formation around the wire, which reduces kinking and possible overstressing of the wire 4 as it emerges from the housing 18 of the activation unit 2 through the toggle 8.

[0062] FIG. 8 illustrates two alternative configurations of the distal restrainers shown in FIG. 7, where the collet-based wire sleeve 49 extends partially distally from the collet 24 and the toggle-based wire sleeve 51 extends proximally from the toggle 8. The toggle-based wire sleeve 51 may also extend distally from the toggle 8. The proximal end of the toggle-based wire sleeve 51 seals and preferably clamps the distal end of the collet-based wire sleeve 49, resulting in a continuous connection between the two, further improving the distal restraining properties of the activation unit 2. Alternatively, the distal end of the collet-based wire sleeve 49 may be configured to seal the proximal end of the toggle-based wire sleeve 51, with a similar effect.

[0063] Figure 9 illustrates a single taper collet 24 in which only the proximal end of the collet 24 is tapered to seat in a complementary taper at the base of the distal recess 44 of the transducer 20. Conversely, Figure 10 illustrates a dual taper collet 24 in which the distal end of the collet 24 is also distally tapered.

[0064] The primary purpose of the collet 24 used in the present invention is to achieve good acoustic coupling between the wire 4 and the rest of the system. In this regard, the transducer 20 and the coupling method must work in unison. In particular, the transducer 20 is designed to resonate at the drive frequency of the system, with coupling interface components optionally including an acoustic horn.

[0065] The shape and dimensions of the transducer 20 are selected to achieve amplification gain while ensuring that the system remains near its operating resonant frequency. Additionally, any modifications to the distal drive face of the transducer 20 to accommodate a connector need to be considered and accounted for in terms of the resonant response.

[0066] FIG. 9 shows the transducer 20 mated with a single tapered, male-threaded collet 24. The collet 24 secures the wire 4 within a threaded bore or recess 44 complementary to the distal end of the transducer 20 when torque is applied to the collet 24 to advance it into the recess 44. A complementary taper at the proximal base of the recess 44 then radially compresses the collet 24 to grip the wire 4. As shown in FIG. 4, when the collet 24 is fully advanced into the recess 44, a distal end portion of the collet 24 remains protruding distally from the distal end of the transducer 20. A suppressor 46 at the proximal end of the recess 44 and a suppression sleeve 48 similar to the sleeve 48 in the collet base shown in FIG. 7 are provided to suppress or attenuate the proximal transmission of ultrasonic energy imparted by the transducer 20 to the wire 4.

[0067] 10 shows the transducer 20 mated with a dual taper collet 24 and cap screw 54. The proximal taper of the collet 24 is received in a countersunk distal recess 44 in the distal end face of the transducer 20. The cap screw 54 similarly receives and complements a taper at the distal end of the collet 24. Torque applied to the cap screw 54 advances the cap screw 54, compressing the collet 24 longitudinally and compressing the collet 24 radially to grip the wire 4.

[0068] Similar to the arrangement shown in FIG. 7, an internal suppressor 46 is disposed within the transducer 20 at the proximal end of the collet 24. The suppressor 46 is an annular collar of superelastic material that surrounds the wire 4 within the lumen 22 of the transducer 20. When the collet 24 is forced proximally into the distal recess 44 of the transducer 20, the suppressor 46 compresses axially and thickens radially, thus deforming around and pressing against the wire 4. The suppressor 46 thereby suppresses or attenuates the proximal transmission of ultrasonic energy imparted by the transducer 20 through the collet 24 to the wire 4. In this arrangement, as well as the arrangement of FIG. 7, multiple suppressors 46 or one longer suppressor 46 can be deployed the length of the transducer body 20.

[0069] FIG. 11 shows an internal containment feature within the housing 18 of the activation unit 2, where the portion of the wire 4 emerging proximally from the transducer 20 passes through a serpentine series of bends 94. Guiding the wire 4 through these tortuous bends 94 attenuates the ultrasonic energy and therefore reduces proximal transmission. The proximal portion of the wire 4 may also extend through a tube 96 having a high coefficient of friction. In that case, the effect of the bends 94 is to increase the frictional forces between the wire 4 and the surrounding tube 96, causing further attenuation of the ultrasonic energy. Friction also occurs between the wire 4 and features such as the lateral pins 98 that define the bends 94.

[0070] Additionally, the proximal portion of the wire 4 can be slid through a superelastic tubing, such as silicone, whose inner diameter is equal to or less than the outer diameter of the wire. To illustrate this former possibility, Figures 12 and 13 correspond to the pneumatic clamping arrangement of Figure 6, but show a restraining medium 100 disposed around the wire proximal to the pneumatic micro-chuck 32.

[0071] Also, the proximal portion of the wire 4 may be actively clamped or bent off-center by mechanisms that are independent of or coupled to the main user toggle 8. For example, FIG. 14 shows how the proximal portion of the wire 4 may be captured between offset cams 102 in the activation unit 2. FIG. 15 shows a push button restraining mechanism 104 that may be pressed radially, inwardly against the proximal portion of the wire 4 within the activation unit 2. The push button restraining mechanism 104 is configured to exert pressure on the wire 4, thus restraining displacement of the wire 4.

[0072] In Fig. 16a, the housing 18 of the activation unit 2 is fitted at its proximal end with a proximal cap with a restraining mechanism 105 that can be rotated to bring the laterally offset helical formation into restraining contact with the proximal portion of the wire 4. Fig. 16b shows a cross-sectional view through the restraining mechanism 105.

[0073] 15 and 16a, the proximal portion of the wire 4 is surrounded by a strain relief feature that extends proximally from the housing 18, which also affects lateral restraint of the wire 4.

[0074] FIG. 17 illustrates how variation in proximal vibration can be achieved automatically by a user rotating the distal toggle 8. As the toggle 8 rotates, it displaces a guide cable 106 within the housing of the activation unit 2. This pulls a spring-loaded element 108, which acts on a portion of the wire 4 proximally via a friction collar 110 around which the wire 4 extends. By increasing the friction force on the wire 4 to dampen its vibration, this attenuates ultrasonic energy that would otherwise be directed proximally from the activation unit 2. In other embodiments, the friction collar 110 can be electronically controlled. A similar distal toggle 8 can then be used to adjust the friction force via an electronic coupling between the distal toggle 8 and the friction collar 10.

[0075] 18 illustrates another way in which the proximal portion of the wire 4 can be clamped to suppress ultrasonic vibrations. Here, the housing 18 of the activation unit 2 supports a lever 112 that extends longitudinally along the housing 18. The proximal end of this lever 112 is biased by a spring 114 into suppressing contact with the proximal portion of the wire 4. When it is desired to remove the wire 4 from the activation unit 2, the distal end of the lever 112 can be depressed to release the pressure exerted by the lever 112 on the proximal portion of the wire 4.

[0076] Constraint features can also be incorporated into the collet 24. For example, FIG. 19 illustrates a split collet 24 in which the proximal portion of the wire 4 is forced into a serpentine path defined by opposing guide formations 76 in opposing faces of the collet 24. Specifically, longitudinally staggered projections 76 alternate between opposing portions of the collet 24 to define an undulating path therebetween. The projections 76 can be made of a compliant material to effectively constrain vibration excitation.

[0077] FIG. 20 shows how the lumen of the transducer or horn can be infused with foam or elastic polymer material to negate activity in the proximal portion of the wire extending proximally from the coupling and activation unit.

[0078] 21-24, these figures show a safety feature in which a rigid tube 176 protruding distally from the distal end of the activation unit 2 surrounds and protects the distal portion of the wire 4. The primary purpose of the tube 176 is to prevent the handheld activation unit 2 from advancing too distally towards the patient during a procedure, i.e., to prevent the wire 4 from breaking and potentially becoming lost within the patient. This tube 176 has the secondary benefit of providing strain relief and lateral restraint to the distal portion of the wire 4.

[0079] In particular, as shown in Fig. 22, tube 176 acts as a spacer that prevents the user from advancing activation unit 2 all the way into catheter entry port 178, commonly referred to in the art as a "luer." The length of tube 176 imposes a separation distance between activation unit 2 and entry port 178. The distal end of tube 176 may be bulbous or otherwise enlarged, as shown, and may act as an end stop or insertion limiter that prevents the tube from entering the entry port.

[0080] The length of tube 176 ensures that even if wire 4 breaks, a section of wire 4 will always remain outside the patient's body. Specifically, if wire 4 breaks near its attachment point with transducer 20 in activation unit 2, a length of wire 4 that is at least as long as tube 176, and typically somewhat longer than tube 176, will always remain outside inlet port 178. In this case, tube friction between wire 4 and tube 176 will help prevent wire 4 from slipping distally along tube 176 and into the patient's body.

[0081] 23 and 24 show that the tube 176 has the additional attribute of being radially compressible between the fingers of a user in the event of breakage, allowing the user to grasp the wire 4 within the tube 176. This helps the user to prevent the broken end of the wire 4 from being pulled into the patient's body. The tube 176 may be compressible in this manner at its proximal end, or at any point along its length, but is preferably compressible at or near its distal end, as shown in the figures.

[0082] Advantageously, the tube 176 can also be easily removed from the activation unit 2 to allow quick access to the wire 4. To this end, the tube 176 is easily removable from the distal end of the activation unit 2 by releasing a detachable connector 180 at the proximal end of the tube 176 from the distal side of the toggle 8, whereupon the tube 176 can be removed from the activation unit 2 by, for example, threading or a push / pull arrangement.

[0083] Thus, the user can tighten the tube 176 to grasp the broken wire 4 and then, while still grasping the wire 4, the user can pull the tube 176 away from the activation unit 2 to ensure that the wire 4 remains outside the patient's body.

[0084] 25, which shows a flexible tubular protective catheter or sheath 182. At the beginning of the procedure, the sheath 182 extends along and around the distal portion of the wire 4 that extends between the activation unit 2 and the luer or introducer that defines the entry port 178 for introduction into the patient's body. The purpose of the sheath 182 is to surround and protect this length of the wire 4 that would otherwise be exposed before advancing into the patient's body. The wire 4 can easily pass through the loose sheath 182, while the sheath 182 can prevent the wire 4 from coming into contact with any material that may contaminate the wire 4 or modify, and in particular inhibit, the vibration of the wire 4.

[0085] The sheath 182 is particularly useful when a long wire 4 must be inserted into a patient's body, for example to cross an occlusion in the distal tibial or foot artery. In particular, the tubing 182 assists in such substantial lengths of wire 4 being inserted in a single continuous motion, rather than intermittently in a series of shorter motions, as would be the case if the activation unit 2 were instead repeatedly clamped and released from the wire 4.

[0086] Thus, rather than being held close to the introducer 178, the activation unit 2 is coupled to the wire 4 at a location remote from the introducer 178, thus preparing the entire length of the wire 4 for introduction into the target vessel. As a result, a user can simply clamp the activation unit 2 to the wire 4 at a proximal location of a meter or more from the patient's body, and then activate and deliver a long section of the wire 4 into the body with a single, continuous action.

[0087] The sheath 182 must not impede distal movement of the activation unit 2 and wire 4 into the introducer 178. Thus, the sheath 182 can collapse along its length or bellows as the activation unit 2 and wire 4 advance distally. In another approach, as shown here, the sheath 182 has a longitudinal slit 184, groove chuck, or other closure along its length that is scored longitudinally and then peeled away from the wire 4 to provide clearance as the activation unit 2 and wire 4 advance distally together through the sheath 182.

[0088] 26, the displacement or movement of the proximal end of the wire 4 is mitigated by a flexible tubular sleeve 71 that surrounds the proximal portion of the wire 4 where it exits the housing 18 of the activation unit 2. This flexible tubular sleeve, made, for example, of an elastic polymer material, is resistant to the wire 4, thereby inhibiting movement of the wire.

[0089] FIG. 27 shows a similar embodiment of the activation unit 2. In addition to what is already shown in FIG. 26, this embodiment further comprises a clamp 72 that squeezes a flexible tubular sleeve 71 onto the wire 71. This clamp 72 can be longitudinally movable along the sleeve 71 to the position that provides the best restraining effect. In FIG. 28, the clamp 72 is replaced by a collet 73 that can also be moved along the sleeve 71. Furthermore, the collet 73 can be adapted so that it controls the clamping force with which the clamp clamps the tubular sleeve 71 and the wire 4 extending therethrough. The double collet 73 provides a restraining feature that can compress the wire axially or longitudinally and clamp the wire 4 at more than one point. In a further embodiment, the clamp 72 of FIG. 27 and the collet 73 of FIG. 28 can be combined.

[0090] In FIG. 29, the activation unit 2 includes a proximal twist lock 74 that clamps against the proximal portion of the wire 4 and couples it to the housing 18 of the activation unit 2 to inhibit displacement or movement of the proximal portion of the wire 4. The proximal twist lock 74 may include a collet 74a or a tubular sleeve that surrounds the wire 4 and is clamped by operating the proximal twist lock 74. In addition, the activation unit 2 may include a similar distal twist lock 75 with a collet 75a that couples the transducer to the distal portion of the wire 4. Either or both of the twist locks 74, 75, but preferably at least the distal twist lock 75, may be combined with a user toggle 8, as disclosed in FIG. 1 and many of the other figures above. Such a user toggle 8 would then be configured to be rotatable independently of the twist locks 74, 75 about the same longitudinal axis. Another mechanism, or operator, may place the wire 4 under tension or compression before locking, or may leave the wire 4 in a neutral state before locking.

[0091] 30a, 30b and 30c show three different arrangements of wire retention formations 76 that can be provided inside the housing 18 of the activation unit 2, preferably at least at its proximal end, to hold the wire 4 firmly and thereby damp the displacement or movement of the proximal part of the wire. These wire retention formations 76 can be provided inside the collet 24, as already shown in FIG. 19, or on any other element that surrounds the wire 4 and is firmly attached inside the housing 18. The wire retention formations 76 can be spring-loaded and are resistant to the proximal part of the wire 4 and suppress vibrations of said proximal part. In FIG. 30a, four wire retention formations 76 together provide two contact points with the wire 4. In FIG. 30b, three wire retention formations 76 provide three contact points. In Fig. 30c, the three wire retention formations 76 are arranged so that the wire 4 follows a serpentine path through longitudinally staggered contact points similar to the path shown in Fig. 19. Combinations and variations of the arrangements shown in Figs. 30a, 30b, and 30c will be apparent to those skilled in the art. It is further noted that in the embodiment of Fig. 11, a similar arrangement can be used for the lateral pin 98.

[0092] In the embodiment of FIG. 31, an elastic plug 77 or grommet is provided that can be pushed into the proximal end of the central port 22 extending through the housing 18 and that is resistant to the proximal portion of the wire 4 extending therethrough. The plug 77 is designed to fit snugly within the opening of the central port 22 through which the wire 4 extends. Preferably, the plug 77 is made of rubber or a different but similar moldable and / or elastic material. Pushing the plug 77 into the central port 22 compresses the elastic plug 77 and pinches the wire 4, thereby further restricting lateral movement of the proximal portion of the wire 4.

[0093] In FIG. 32, a tubular flexible membrane 78 is provided within the central port 22 of the housing 18. The tubular flexible membrane 78 defines an annular chamber that can be expanded or inflated by applying fluid pressure through a port 79 in the housing 18 that communicates with the chamber. The port 79 can be connected to an external fluid reservoir, and a pump can pump fluid into the tubular flexible membrane 78 to force the membrane 78 in a radially inward direction against the proximal portion of the wire 4 to inhibit vibration of that portion of the wire 4. When the fluid pressure is relieved, the flexible membrane 78 contracts and the central port 22 reopens, thereby allowing movement of the wire 4 relative to the activation unit 2 for adjustment, insertion, or removal of the wire 4. The fluid can be any type of liquid, such as water. Alternatively, the fluid can be air, in which case the membrane 78 is pneumatically operated. Although the port 79 shown in FIG. 32 is positioned to connect to an external fluid reservoir, alternative embodiments may use a fluid reservoir that is integrated within the housing 18.

[0094] Most of the above embodiments show means for restraining motion at the proximal end of the wire 4, primarily for the safety of the user, as well as to avoid damage to expensive and sensitive equipment, and indeed to the wire itself. However, some wire motion restraint may also be desirable at the distal end of the activation unit 2. Proper distal restraint increases the efficiency and effectiveness of the intravascular device by transporting energy from the transducer to the active distal tip portion of the wire 4 primarily by longitudinal undulations, without unnecessarily losing energy to lateral motion of the wire 4 along the way.

[0095] 33 illustrates one way in which distal restraint of the wire 4 can be achieved. In this figure, a thin sheath 81 emerges from the distal end of the housing 18 of the activation unit 2 to surround a portion of the wire 4 that restrains lateral vibration of the distal portion of the wire 4. The outer diameter of the sheath 81 is small enough to allow it to be fitted into a catheter that supports the wire 4. In one embodiment, the sheath 81 can be realized as a coating on the wire 4, such as a painted layer.

[0096] Figures 34a, 34b, and 34c provide three variations of catheters or sheaths configured to provide proximal and / or distal restraint. Each of these sheaths can be an individual sleeve, as already described with reference to Figure 33. Such individual sleeves can fit tightly or loosely around the wire 4. Alternatively, the sheath can be coated or applied onto the wire 4. The sheath, sleeve, or coating can be a continuous sheath 82 as shown in Figure 34a, a spiral or helical sheath 83 as shown in Figure 34b, or a discontinuous or stepped sheath 84 as shown in Figure 34c. The sheath may have windows cut out along its length. Thus, selective or intermittent restraint can be achieved through selective or intermittent covering or surrounding the wire 4. The intermittent covering can create individual sections of larger outer diameter than the outer diameter of the wire.

[0097] All of the sheaths 82, 83, 84 have the effect of increasing the weight and inertia of the wire 4, thereby limiting the movement of the coated portions of the wire 4. If the displacement of the wire 4 is at its maximum where it coincides with the restraining wall section of the discontinuous or windowed sheath, this can have a positive effect on the restraining movement of the wire 4, as shown in Figure 34c.

[0098] At the distal end of the wire, the sheath may be thinner than at its proximal end, so that the distal portion of the wire 4 can fit into a catheter supporting the wire 4. To maintain the possibility of translating the activation unit 2 along the wire, the sheath at the proximal end may be movable along the wire 4. Alternatively, sections of the covering may be configured to be removable, if desired. In one embodiment, the same coating or applied covering may be provided along the entire wire 4, with an additional covering that is removable or movable only at the proximal end.

[0099] 35a and 35b show a variation of the distal restraint mechanism in which a lever 85 is pivotable relative to the housing 18 and bears against a wire 4 projecting distally from an acoustic horn 26 of a transducer 20 within the housing. The lever 85 bears against a portion of the wire 4 disposed within the housing 18 between the horn 26 and the distal end of the housing 18. A strain relief feature around the wire 4 extends distally from that end of the housing 18. The lever 85 bears against the wire 4 either directly, as shown in FIG. 35a, or indirectly through an intermediate pad 86 interposed between the lever 85 and the wire 4, as shown in FIG. 35b.

[0100] It should be noted that many features of the various embodiments described above are not limited to only those particular embodiments: a person skilled in the art will be able to combine features from one embodiment with features of other embodiments whenever this is technically possible and makes sense from a practical point of view.

Claims

1. An intravascular device for crossing an obstacle in a blood vessel, said device comprising: - an elongated intravascular element, such as a wire; an ultrasonic transducer mechanically coupled to the intravascular element for ultrasonically exciting a distal tip portion of the intravascular element to facilitate the traversal of the obstacle; one or more restraining features mechanically coupled to the intravascular element at a location away from the distal tip portion to dampen lateral displacement of the intravascular element; the ultrasonic transducer is contained within a transducer housing; The intravascular device, wherein the transducer housing further comprises at least one of the one or more suppression features.

2. 10. The intravascular device of claim 1, wherein the one or more dampening features are mechanically coupled to the intravascular element to attenuate lateral displacement of the intravascular element at a location between the ultrasound transducer and the distal tip portion.

3. The intravascular device of claim 1 or 2, wherein at least one of the one or more suppression features is mechanically coupled to the intravascular element outside the transducer housing.

4. The intravascular device of any one of claims 1 to 3, wherein the ultrasonic transducer is coupled to the intravascular element such that the intravascular element extends proximally as well as distally from the ultrasonic transducer.

5. The intravascular device of claim 4 , wherein the one or more dampening features are mechanically coupled to the intravascular element at a location proximal to the ultrasound transducer to attenuate displacement of the intravascular element.

6. 6. The intravascular device of claim 1, wherein the ultrasonic transducer comprises a lumen for retaining the intravascular element, and the one or more restraining features comprise at least one restraining ring or sleeve of elastic material disposed between the intravascular element and an inner surface of the lumen.

7. An intravascular device for crossing an obstacle in a blood vessel, said device comprising: - an elongated intravascular element, such as a wire; an ultrasonic transducer mechanically coupled to the intravascular element for ultrasonically exciting a distal tip portion of the intravascular element to facilitate the traversal of the obstacle; one or more restraining features mechanically coupled to the intravascular element at a location away from the distal tip portion to dampen lateral displacement of the intravascular element; the ultrasonic transducer is contained within a transducer housing; An intravascular device, wherein the transducer housing comprises a lumen for retaining the intravascular element, and the restraining feature comprises a liquid restraining medium disposed between the intravascular element and an inner surface of the lumen.

8. 8. The intravascular device of claim 1, wherein the transducer housing includes a distal opening, the intravascular element extends through the distal opening, and the restraining feature includes a restraining ring or sleeve disposed between the intravascular element and an inner surface of the distal opening.

9. 9. The intravascular device of claim 1, further comprising a collet, the collet surrounding the intravascular element, a proximal end of the collet being removably coupled to the ultrasonic transducer, and the restraining feature comprising a restraining ring or sleeve disposed around the intravascular element and within a distal end of the collet.

10. An intravascular device for crossing an obstruction in a blood vessel, said device comprising: - an elongated intravascular element, such as a wire; an ultrasonic transducer mechanically coupled to the intravascular element for ultrasonically exciting a distal tip portion of the intravascular element to facilitate the traversal of the obstacle; one or more restraining features mechanically coupled to the intravascular element at a location away from the distal tip portion to dampen lateral displacement of the intravascular element; the ultrasonic transducer is contained within a transducer housing; The intravascular device, wherein the restraining feature comprises a plurality of guide formations disposed within the transducer housing and positioned in direct contact with opposing sides of the intravascular element to prevent lateral movement of the intravascular element in a direction perpendicular to the intravascular element itself.

11. The intravascular device of claim 10 , wherein the plurality of guide formations define a generally straight path through the transducer housing.

12. The intravascular device of claim 10 , wherein the plurality of guide formations define a tortuous or undulating path through the transducer housing.

13. The intravascular device of any one of claims 10 to 12, wherein the guide formation is spring biased towards the intravascular element.

14. 14. The intravascular device of claim 10, further comprising a collet, the collet surrounding the intravascular element, a proximal end of the collet being removably coupled to the ultrasonic transducer, and the guide formation being provided inside the collet.

15. An intravascular device for crossing an obstruction in a blood vessel, said device comprising: - an elongated intravascular element, such as a wire; an ultrasonic transducer mechanically coupled to the intravascular element for ultrasonically exciting a distal tip portion of the intravascular element to facilitate the traversal of the obstacle; one or more restraining features mechanically coupled to the intravascular element at a location away from the distal tip portion to dampen lateral displacement of the intravascular element; the ultrasonic transducer is contained within a transducer housing; a rigid tube disposed distal to the transducer housing and surrounding the intravascular element; An intravascular device, wherein the rigid tube comprises a compressible portion.

16. The intravascular device of claim 15 , wherein the rigid tube is removably attached to the transducer housing.

17. The intravascular device of claim 15 , wherein the compressible portion is disposed at a distal tip of the rigid tube.

18. An intravascular device for crossing an obstruction in a blood vessel, said device comprising: - an elongated intravascular element, such as a wire; an ultrasonic transducer mechanically coupled to the intravascular element for ultrasonically exciting a distal tip portion of the intravascular element to facilitate the traversal of the obstacle; one or more restraining features mechanically coupled to the intravascular element at a location away from the distal tip portion to dampen lateral displacement of the intravascular element; the ultrasonic transducer is contained within a transducer housing; at least one of the one or more suppression features is mechanically coupled to the intravascular element outside the transducer housing; An intravascular device, wherein the restraining feature comprises a flexible, resilient tubular sleeve disposed at least partially proximal to the transducer housing, the flexible, resilient tubular sleeve surrounding and retaining a portion of the intravascular element.

19. 20. The intravascular device of claim 18, wherein the restraining feature further comprises an adjustable clamp for selectively clamping a portion of the flexible, resilient tubular sleeve.

20. 20. The intravascular device of claim 18 or 19, wherein the restraining feature further comprises an adjustable collet for selectively constricting a portion of the flexible, resilient tubular sleeve.

21. An intravascular device for crossing an obstacle in a blood vessel, said device comprising: - an elongated intravascular element, such as a wire; an ultrasonic transducer mechanically coupled to the intravascular element for ultrasonically exciting a distal tip portion of the intravascular element to facilitate the traversal of the obstacle; one or more restraining features mechanically coupled to the intravascular element at a location away from the distal tip portion to dampen lateral displacement of the intravascular element; the ultrasonic transducer is contained within a transducer housing; An intravascular device, wherein the transducer housing includes a distal opening, the intravascular element extends through the distal opening, and the transducer housing further includes a pneumatic micro-chuck for pneumatically clamping the intravascular element at the distal opening.

22. An intravascular device for crossing an obstruction in a blood vessel, said device comprising: - an elongated intravascular element, such as a wire; an ultrasonic transducer mechanically coupled to the intravascular element for ultrasonically exciting a distal tip portion of the intravascular element to facilitate the traversal of the obstacle; one or more restraining features mechanically coupled to the intravascular element at a location away from the distal tip portion to dampen lateral displacement of the intravascular element; the ultrasonic transducer is contained within a transducer housing; An intravascular device, wherein the restraining feature comprises a pair of two rotatably adjustable offset cams for clamping the intravascular element between the offset cams, the offset cams being disposed inside the transducer housing proximal to the transducer.

23. An intravascular device for crossing an obstruction in a blood vessel, said device comprising: - an elongated intravascular element, such as a wire; an ultrasonic transducer mechanically coupled to the intravascular element for ultrasonically exciting a distal tip portion of the intravascular element to facilitate the traversal of the obstacle; one or more restraining features mechanically coupled to the intravascular element at a location away from the distal tip portion to dampen lateral displacement of the intravascular element; the ultrasonic transducer is contained within a transducer housing; An intravascular device, wherein the restraining feature comprises a push button restraining mechanism that can be pressed radially inward against the intravascular element, the push button restraining mechanism being disposed inside the transducer housing proximal to the transducer.

24. An intravascular device for crossing an obstruction in a blood vessel, said device comprising: - an elongated intravascular element, such as a wire; an ultrasonic transducer mechanically coupled to the intravascular element for ultrasonically exciting a distal tip portion of the intravascular element to facilitate the traversal of the obstacle; one or more restraining features mechanically coupled to the intravascular element at a location away from the distal tip portion to dampen lateral displacement of the intravascular element; the ultrasonic transducer is contained within a transducer housing; An intravascular device, wherein the restraining feature comprises a rotatably adjustable proximal cap that can be rotated to bring a laterally offset helical formation into restraining contact with the intravascular element, the rotatably adjustable proximal cap being disposed inside the transducer housing proximal to the transducer.

25. An intravascular device for crossing an obstacle in a blood vessel, said device comprising: - an elongated intravascular element, such as a wire; an ultrasonic transducer mechanically coupled to the intravascular element for ultrasonically exciting a distal tip portion of the intravascular element to facilitate the traversal of the obstacle; one or more restraining features mechanically coupled to the intravascular element at a location away from the distal tip portion to dampen lateral displacement of the intravascular element; the ultrasonic transducer is contained within a transducer housing; An intravascular device, wherein the restraining feature comprises a controllable friction collar surrounding the intravascular element for applying an adjustable frictional force to the intravascular element, the controllable friction collar being disposed inside the transducer housing proximal to the transducer.

26. 26. The intravascular device of claim 25, wherein the transducer housing further comprises a distal toggle operably coupled to the controllable friction collar for adjusting the frictional force.

27. An intravascular device for crossing an obstruction in a blood vessel, said device comprising: - an elongated intravascular element, such as a wire; an ultrasonic transducer mechanically coupled to the intravascular element for ultrasonically exciting a distal tip portion of the intravascular element to facilitate the traversal of the obstacle; one or more restraining features mechanically coupled to the intravascular element at a location away from the distal tip portion to dampen lateral displacement of the intravascular element; the ultrasonic transducer is contained within a transducer housing; An intravascular device, wherein the restraining feature comprises a lever extending longitudinally along the transducer housing, the lever being spring biased into restraining contact with the intravascular element at a location proximal to the transducer.

28. An intravascular device for crossing an obstacle in a blood vessel, said device comprising: - an elongated intravascular element, such as a wire; an ultrasonic transducer mechanically coupled to the intravascular element for ultrasonically exciting a distal tip portion of the intravascular element to facilitate the traversal of the obstacle; one or more restraining features mechanically coupled to the intravascular element at a location away from the distal tip portion to dampen lateral displacement of the intravascular element; the ultrasonic transducer is contained within a transducer housing; An intravascular device, wherein the transducer housing further comprises a rotatable twist lock that surrounds the intravascular element and is configured to apply an adjustable clamping force to the intravascular element.

29. 30. The intravascular device of claim 28, wherein the rotatable twist lock is provided at a proximal and / or distal end of the transducer housing.

30. An intravascular device for crossing an obstacle in a blood vessel, said device comprising: - an elongated intravascular element, such as a wire; an ultrasonic transducer mechanically coupled to the intravascular element for ultrasonically exciting a distal tip portion of the intravascular element to facilitate the traversal of the obstacle; one or more restraining features mechanically coupled to the intravascular element at a location away from the distal tip portion to dampen lateral displacement of the intravascular element; the ultrasonic transducer is contained within a transducer housing; An intravascular device, wherein the restraining feature comprises a grommet configured to surround the intravascular element at a location proximal to the transducer housing and to fit within a proximal opening of the transducer housing.

31. An intravascular device for crossing an obstacle in a blood vessel, said device comprising: - an elongated intravascular element, such as a wire; an ultrasonic transducer mechanically coupled to the intravascular element for ultrasonically exciting a distal tip portion of the intravascular element to facilitate the traversal of the obstacle; one or more restraining features mechanically coupled to the intravascular element at a location away from the distal tip portion to dampen lateral displacement of the intravascular element; An intravascular device, wherein the restraining feature comprises a tubular structure having a lumen for retaining the intravascular element, the tubular structure comprising a fluid pocket and a flexible inner wall separating the fluid pocket from the lumen, the fluid pocket being inflatable or expandable to reduce a diameter of the lumen.

32. The intravascular device of any one of claims 1 to 31, wherein the containment feature comprises a sheath and / or coating surrounding at least a portion of the intravascular element distal to the transducer.

33. An intravascular device for crossing an obstruction in a blood vessel, said device comprising: - an elongated intravascular element, such as a wire; an ultrasonic transducer mechanically coupled to the intravascular element for ultrasonically exciting a distal tip portion of the intravascular element to facilitate the traversal of the obstacle; one or more restraining features mechanically coupled to the intravascular element at a location away from the distal tip portion to dampen lateral displacement of the intravascular element; the containment feature includes a sheath and / or coating surrounding at least a portion of the intravascular element distal to the transducer; An intravascular device, wherein the sheath and / or coating forms a continuous covering for the intravascular element.

34. An intravascular device for crossing an obstacle in a blood vessel, said device comprising: - an elongated intravascular element, such as a wire; an ultrasonic transducer mechanically coupled to the intravascular element for ultrasonically exciting a distal tip portion of the intravascular element to facilitate the traversal of the obstacle; one or more restraining features mechanically coupled to the intravascular element at a location away from the distal tip portion to dampen lateral displacement of the intravascular element; the containment feature includes a sheath and / or coating surrounding at least a portion of the intravascular element distal to the transducer; An intravascular device, wherein the sheath and / or coating forms a helical covering of the intravascular element.

35. An intravascular device for crossing an obstacle in a blood vessel, said device comprising: - an elongated intravascular element, such as a wire; an ultrasonic transducer mechanically coupled to the intravascular element for ultrasonically exciting a distal tip portion of the intravascular element to facilitate the traversal of the obstacle; one or more restraining features mechanically coupled to the intravascular element at a location away from the distal tip portion to dampen lateral displacement of the intravascular element; the containment feature includes a sheath and / or coating surrounding at least a portion of the intravascular element distal to the transducer; An intravascular device, wherein the sheath and / or coating forms a discontinuous covering of the intravascular element.

36. 1. An intravascular device for crossing an obstruction in a blood vessel, the device comprising: - an elongated intravascular element; - an ultrasonic energy source including an ultrasonic transducer; a coupling for transmitting, in use, the ultrasonic energy along the intravascular element from the source to an active tip portion at a distal end of the intravascular element, the coupling being arranged to couple the source to the intravascular element at any of a plurality of individually operable positions along the length of the intravascular element for transmission of the ultrasonic energy to the active tip portion, the coupling being further arranged to clamp the intravascular element at any of the operable positions when the intravascular element extends through the coupling and the source and has portions extending proximally and distally from the coupling and the source, respectively; The intravascular device further includes a restraining feature mechanically coupled to the intravascular element to attenuate lateral displacement of the intravascular element at a location proximally and / or distally away from the distal tip portion of the transducer.

37. An intravascular device according to claim 36, further comprising one or more of the features according to any one of claims 1 to 35.

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