Intravascular device

Abstract

An intravascular device for crossing an obstruction in a blood vessel includes: an elongated intravascular element, such as a guide wire; an ultrasonic transducer that is mechanically coupled to the intravascular element to ultrasonically excite a distal tip portion of the intravascular element to facilitate crossing of the obstruction; and one or more damping features that are mechanically coupled to the intravascular element to attenuate lateral displacement of the intravascular element at positions remote from the distal tip portion.

Description

Technical Field

[0001] The present invention relates to treating ischemia by using an ultrasound-activated wire or other elongate element to penetrate a blockage in a blood vessel and facilitate the introduction of a subsequent treatment device.

[0002] Previous Patent Applications

[0003] The present invention develops concepts expressed in the international patent application published as WO 2020 / 094747 and the unpublished GB patent application No. 2006665.0, the content of which is incorporated herein by reference. Background Art

[0004] In endovascular surgery, arteries are selected and recruited for access to the vasculature. The selection is based on the artery's ability to accommodate the passage of the intended diagnostic or therapeutic device to the target site and the extent to which it can minimize tissue and patient trauma.

[0005] In revascularization surgery, for example, in peripheral arteries or veins, access is typically made surgically through incisions and punctures in the femoral artery, popliteal artery, tibial artery, and / or pedal arteries, which is commonly referred to in medical terminology as the Seldinger technique. Once access is obtained, a guidewire and a guide sheath are inserted into the blood vessel and secured at the site. This sheath serves as a port for the introduction, withdrawal, and replacement of devices and minimizes abrasion of the arterial tissue. A guiding catheter and a guidewire are then introduced into the artery to provide further protection and assist in device navigation and delivery of treatment to the target site.

[0006] The guidewire is carefully advanced along the lumen of the blood vessel to avoid any trauma to the vessel wall and navigate the guidewire to the site of obstruction. In a successful procedure, the guidewire is then advanced across or through the obstruction and held in place to act as a guide through 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 blood vessels or other body cavities for examination, diagnosis, and different types of treatment.

[0007] Guidewires are used, for example, in balloon angioplasty, gastrointestinal, urological, and gynecological procedures. All of these procedures require creating a passage through a blockage to facilitate the passage of larger and usually bulkier devices to the site of the lesion or other target tissues distal to the lesion within the body.

[0008] Guidewires are critical for therapeutic interventions and are made of different materials, most typically stainless steel and various alloys, including NiTi (nitinol), and have many different designs. Their manufacture involves altering the chemical composition and microstructure morphology of the material, such as by cold working the material while forming it into a wire, and then machining the wire into different size designs and applying different heat treatments to achieve the desired properties. As an example, a specific taper can be machined along the length of the wire to produce a differential degree of flexibility along the length of the wire. Thus, the wire will have sufficient flexibility at its distal end to conform to the shape of the blood vessel and have the strength to transmit force to the tip ("tip strength") or force through a lesion.

[0009] In conventional guidewires, the tapered section is wrapped in a coil or sheath material, which allows flexibility through the taper while enabling the transmission of force through the coil to the distal tip of the wire. As will be explained, in the wires of the present invention, such coil or sheath material is not necessary because, even without a coating or sheath on the wire, force is transmitted by ultrasonic energy to excavate the lumen.

[0010] The length of the guidewire used in endovascular procedures also varies depending on the distance it is considered likely to be manipulated. As an example, guidewires with lengths typically ranging from 750 mm up to 900 mm are used for many peripheral applications where they may be introduced into the femoral or popliteal anatomy, or where it is necessary to track and cross occlusions in the ipsilateral iliofemoral popliteal artery and the infrapopliteal artery. The lengths of the guidewires used in ipsilateral and coronary applications tend to be approximately 1200 mm, 1500 mm, or 1700 mm. In fact, guidewires that can be tracked contralaterally may be longer, with lengths possibly ranging from approximately 2000 mm to 2250 mm or 2500 mm or 3000 mm. The most common guidewire lengths on the market are 1750 mm, 1950 mm, and 3000 mm.

[0011] In many cases, an extension guidewire can be used to facilitate the deployment of certain therapeutic devices. In this case, certain features may be required at the proximal end of the guidewire.

[0012] Many conventional intravascular wires are passive mechanical devices without active components. Passive wires do not deliver any energy other than that applied by the clinician. They are operated by being pushed, pulled, and twisted at their proximal ends to navigate to the occluded site and then pushed through or around the occlusion. They have different configurations and designs to facilitate entry into and passage through lesions in different anatomical structures and for different devices. However, in many cases, the occlusion is too challenging for conventional wires to cross. These passive wires do not work as expected for guidewires, or are limited when attempting to cross near-occluded or fully occluded blockages that may also be significantly calcified. In cases where these passive wires are tracked around an occlusion, such as in a subintimal situation, such wires are generally unsuccessful in re-entering the true lumen.

[0013] The present invention relates to using ultrasonic vibrations transmitted along a wire to cross an occlusion. Transmission of ultrasonic vibrations along small-diameter catheters and assemblies is disclosed in US 3433226. US 5971949 describes the transmission of ultrasonic energy through waveguides of different configurations and tip geometries. US 5427118 describes an ultrasonic guidewire system but does not discuss in detail the proximal geometry of the wire or how it facilitates subsequent devices via a wire-through approach.

[0014] Many current single-transducer systems are not ultrasonic-activated guidewires but ultrasonic-activated catheters containing wire members for agitating and ablating material. Such systems are described in US 6855123 and US 4979939. These catheters themselves require a separate passive guidewire to assist them in navigation and, therefore, they are tools for facilitating the crossing of a separate guidewire through an occlusion. US9629643 shows a system having a series of distal tip configurations but all require a separate guidewire to enter.

[0015] These devices are designed to deliver alternative methods of revascularization and are commonly described as atherectomy devices, crossing devices, or vascular preparation devices. With limited exceptions, these devices are not consistent with the purpose of crossing lesions and serving as a device delivery system. In the art, these ultrasonic devices and conduit-rebuilding wire devices enhance revascularization and reduce the volume of the lesion by removing the plaque forming the lesion, thereby providing or achieving atherectomy.

[0016] In early, late, and current designs, ultrasonic generator systems have become large due to the acoustics used, and they have become large units scaled to produce multiple frequencies and control pulsed waves. Additionally, practical considerations mean that known systems typically include separate components. For example, many systems are designed such that the signal generator is housed in a unit separate from the transducer, and some are mounted on large trolley units, consoles, or brackets that occupy significant space in a clinical environment. US 6450975, US 2008 / 0228111, and US 9282984 all describe such systems.

[0017] Ultrasound-activated catheter and wire systems have been considered in the past as a method for atherectomy and preparing blood vessels for angioplasty treatment. Some products were commercially available in the past, some products are still available on the market, and some new systems have recently been launched. Such catheter and wire systems typically incorporate an ultrasonic generator and an ultrasonic transducer. The ultrasonic generator converts mains electricity into an ultrasonic waveform defined by its voltage amplitude, current, and frequency. The ultrasonic transducer, and typically a horn, converts electrical energy into high-frequency mechanical vibrations defined by the frequency and amplitude of the vibrations.

[0018] A small-diameter wire waveguide is directly coupled to the transducer at its proximal end, or via any horn, and transmits the mechanical vibrations to the distal tip of the wire. This causes the distal tip of the wire waveguide to vibrate at a desired amplitude and frequency, with the aim of ablating material and ultimately facilitating revascularization or recanalization of a blood vessel and anatomical structure throughout the body. Tissues and materials near the distal tip are affected by a combination of the ultrasonic movement of the tip and its direct mechanical abrasion, ablation, and cavitation from the pressure wave component and acoustic streaming that removes the ablated material from the area surrounding the tip.

[0019] In known ultrasound-activated intravascular wire systems, the proximal end of the guide wire is connected to the transducer. In the patent application published as WO2020 / 094747, the wire passes through the transducer and extends not only distally from it 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 cutting it. The adjustable total length of the distal portion of the wire can be very useful for practical purposes, such as being adapted to the expected length of the trajectory that the wire tip needs to travel within the patient's body. Also, control of the wire is enhanced while adjusting or reconnecting the activation source to maintain its in-situ placement within the blood vessel lumen. Additionally, the adjustable-length distal portion of the wire helps to achieve and optimize resonance at the distal tip at any desired frequency.

[0020] When using ultrasonic energy to excite a wire, it is desirable to maximize the displacement amplitude at the distal tip of the wire to ablate lesions. Conversely, in the case where the guide wire extends proximally from the transducer, it is desirable to minimize the displacement or movement of the proximal portion of the wire, which is outside the patient's body and can in fact freely hang proximally from the activation unit.

[0021] An object of the present invention is to solve one or more drawbacks associated with the prior art. Summary of the Invention

[0022] To achieve this object, there is provided an intravascular device for crossing an obstruction in a blood vessel. The intravascular device includes an elongate intravascular wire, an ultrasonic transducer, and one or more damping features. The ultrasonic transducer is mechanically coupled to or in contact with the elongate intravascular wire to ultrasonically excite the distal tip of the elongate intravascular wire to facilitate crossing of the obstruction. The one or more damping features are mechanically coupled to the elongate intravascular wire to attenuate lateral displacement of the elongate intravascular wire at certain positions away from the distal tip. For example, damping can be applied or implemented proximally of the coupling to the transducer to attenuate proximal wave transmission, and damping can be applied or implemented distally of the coupling to inhibit lateral displacement of the portion of the wire that remains outside the vasculature.

[0023] Using the intravascular device according to the present invention, the displacement amplitude at the distal tip of the wire can be maximized in an energy-efficient manner. To obtain optimal efficiency, it is important that most of the power provided by the transducer is transmitted by longitudinal waves through the wire to the distal tip. Thus, any energy loss due to lateral oscillation of the wire is minimized. Using the damping features according to the present invention, such lateral displacement is reduced and the energy efficiency of the intravascular device is increased. The fracture resistance of the wire is also improved.

[0024] In one embodiment of the intravascular device according to the present invention, the one or more damping features are mechanically coupled to the elongate intravascular wire to attenuate lateral displacement of the elongate intravascular wire at one or more positions between the ultrasonic transducer and the distal tip. When attempting to improve the coupling with longitudinal displacement, limit lateral displacement, and improve wire life, it has been found that damping the lateral movement of the distal portion of the intravascular wire - i.e., extending distally from the position where the wire is coupled to the transducer - can provide the best results. A complication therein is that most of the distal portion will be inserted into the patient's body. However, as will be described below, the inventors have found various ways to achieve the desired damping of the wire near the transducer coupling point where the distal section of the wire emerges, without compromising and in fact enhancing the functionality of the device.

[0025] In a preferred embodiment, the ultrasonic transducer is included within a transducer housing. At least some of the damping features may be disposed within or at the transducer housing. Other damping features may be mechanically coupled to the elongate intravascular wire external to the transducer housing. Selective damping may be present at discrete damping locations along the length of the wire.

[0026] In a preferred embodiment, the ultrasonic transducer is coupled to the elongate intravascular wire such that the elongate intravascular wire extends proximally and distally from the ultrasonic transducer. In such embodiments, one or more damping features may be mechanically coupled to the elongate intravascular wire to attenuate lateral and / or longitudinal displacement of the elongate intravascular wire at one or more locations proximal to the ultrasonic transducer.

[0027] By damping the longitudinal and lateral movement of the proximal portion of the intravascular wire, such damping features minimize displacement or movement of the end of the wire outside the patient's body and which can in fact freely hang proximally from the activation unit. Reducing or even avoiding such unwanted lateral movement of the proximal wire portion is important for ensuring the safety of the user and avoiding damage to expensive and sensitive equipment, including the wire itself.

[0028] More generally, the present invention provides devices that enable selective or preferential control of the activation of a wire in any direction. The wire is an example of an elongate 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, such as the first approximately one meter from the proximal end, may have a wire encapsulated in a manner similar to a catheter or coating, while the distal portion of the element extending to the distal end may be an unencapsulated wire. The wire or other element of the present invention can be an internal component of the entire wave delivery system.

[0029] Many specific embodiments of the distal and proximal damping features discussed above - in particular, damping near the transducer proximally and distally at the coupling location - are described below with reference to the accompanying drawings. Some types of damping features are disposed inside the transducer housing, while others are disposed along the wire portion outside the housing. Some damping features are primarily suitable for damping the lateral movement of the distal or proximal wire portion, while other damping features can be used for both the ends or sides of the coupling between the wire and the transducer. Continuous damping, or selective, stepped, or intermittent damping, may be present along the wire. Damping can also be achieved by increasing the weight of 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:

[0031] Figure 1is a schematic perspective view of an ultrasonic wire system according to the present invention.

[0032] Figure 2 is Figure 1 a schematic longitudinal cross - sectional view of the ultrasonic activation unit shown in

[0033] Figure 3 corresponds to Figure 2 , but shows the horn coupled to the transducer within the unit housing.

[0034] Figure 4 corresponds to Figure 2 , but shows the lateral exit of the guide wire from the transducer of the unit.

[0035] Figure 5 corresponds to Figure 4 , but shows the horn coupled to the transducer within the unit housing.

[0036] Figure 6 is Figure 1 a schematic longitudinal cross - sectional view of a variant of the ultrasonic activation unit shown in

[0037] Figure 7 a schematic longitudinal cross - sectional view of the ultrasonic activation unit of the present invention, wherein the ultrasound - to - wire connector and coupling mechanism include a collet for applying torque and a spring - loaded cap.

[0038] Figure 8 shows Figure 7 an alternative configuration of the distal damper shown in

[0039] Figure 9 shows a single - tapered collet within the distal recess of the transducer, having proximal and distal damping.

[0040] Figure 10 shows a double - tapered collet within the distal recess of the transducer, having proximal damping.

[0041] Figure 11 is a longitudinal cross - sectional view of a hand - held ultrasonic activation unit showing internal features for damping the proximal wire within the housing.

[0042] Figure 12 is a longitudinal cross - sectional view of a hand - held ultrasonic activation unit including a medium for counteracting proximal wire movement.

[0043] Figure 13 is showing Figure 12 details of

[0044] Figure 14 is an end view of a cam arrangement for engaging and damping a wire.

[0045] Figure 15 is a longitudinal cross-sectional view of a hand-held ultrasonic activation unit including a button wire damping mechanism.

[0046] Figure 16a is a longitudinal cross-sectional view of a hand-held ultrasonic activation unit including a helical wire damping mechanism.

[0047] Figure 16b is Figure 16a a cross-sectional view of a hand-held ultrasonic activation unit.

[0048] Figure 17 is a longitudinal cross-sectional view of a hand-held ultrasonic activation unit including another wire damping mechanism.

[0049] Figure 18 is a longitudinal cross-sectional view of a hand-held ultrasonic activation unit including another wire damping mechanism that can be disengaged as needed to allow repositioning of the wire.

[0050] Figure 19 is a side view of a longitudinally split collet arranged to dampen proximal excitation of a wire.

[0051] Figure 20 is a schematic view of a wire showing an example of a connection position marker.

[0052] Figure 21 is a perspective view of an ultrasonic activation unit of the present invention fitted with removable distal safety and stress relief features.

[0053] Figure 22 is for use during surgery Figure 21 of an arrangement.

[0054] Figure 23 is showing for use during surgery Figure 21 of an arrangement.

[0055] Figure 24 is showing for use during surgery Figure 21 of an arrangement.

[0056] Figure 25 is a schematic view of a protective sheath for use with the present invention.

[0057] Figure 26 shows an ultrasonic activation unit having proximal damping features.

[0058] Figure 27 shows another ultrasonic activation unit having proximal damping features.

[0059] Figure 28Shows yet another ultrasonic activation unit with proximal damping features.

[0060] Figure 29 Shows an ultrasonic activation unit with proximal and distal twist locks for clamping an intravascular wire at two points.

[0061] Figure 30a 、 30b And 30c show three protrusion arrangements for reducing the lateral movement of an intravascular wire.

[0062] Figure 31 Shows another example of a proximal damper for an ultrasonic activation unit.

[0063] Figure 32 Shows yet another ultrasonic activation unit with proximal damping features.

[0064] Figure 33 Shows an ultrasonic activation unit with distal damping features.

[0065] Figure 34a 、 34b And 34c show three examples of a motion damping wire sheath that provides selective or intermittent damping by selectively or intermittently covering or surrounding the wire.

[0066] Figure 35a And 35b Shows a variant of the distal damping mechanism. Detailed Description

[0067] In the accompanying drawings Figure 1 Shows the overall configuration of a system according to the present invention and illustrates some of the main components of such a system. This example features a hand-held ultrasonic activation unit 2 through which a flexible delivery member in the form of an intravascular wire 4 extends in a centered alignment.

[0068] The wire 4 can be inserted into a patient's vasculature and threaded through to bring its distal end to a lesion site. Once a complex lesion is encountered that obstructs the passage of the wire 4, the activation unit 2 can be coupled to the wire 4 at an appropriate longitudinal position. When activated, the activation unit 2 transmits ultrasonic vibrations to the wire 4 and along the wire, thereby enhancing the wire's 4 ability to pass through the lesion through ablation and other mechanisms. The wire 4 thus serves as a crossing wire for passing through obstructions in a blood vessel and can then be held in place to serve as a guide wire for delivering subsequent treatment devices to treat the lesion.

[0069] Typically, the length of the wire 4 can be greater than 2 m and at most 3 m, for example. For instance, a lesion entering or passing through the foot may involve the wire traveling a distance of typically 1200 mm to 2000 mm within the vasculature, depending on whether an ipsilateral, contralateral, or radial approach is selected. In this regard, the wire 4, which tapers distally to a fine line at its tip, can be navigated to the pedal artery and around the arch of the foot between the dorsal artery and the plantar artery. However, the present invention is not limited to the foot or other peripheral applications and can be used, for example, in coronary applications, where the ability of the wire 4 to navigate to tortuous small-diameter arteries and drill within such tortuous small-diameter arteries is also beneficial.

[0070] The diameter of the distal section of the wire 4 will determine the flexibility of the wire 4 and its ability to conform easily to the shape of the anatomical structure it is intended to pass through. Thus, for example, in a tortuous (foot or coronary) anatomical structure, a distal section of appropriate length and a diameter of, for example, 0.005" to 0.007" combines appropriate flexibility and the ability to drill through certain nickel-titanium alloy occlusive materials.

[0071] The activation unit 2 includes a user control 6 and optionally also includes a display. The activation unit 2 further includes a distal manual lasso 8 that the user can rotate about the central longitudinal axis of the unit 2 and the wire 4. In particular, the activation unit 2 can slide on the wire 4 and can be coupled to the wire 4 at a plurality of longitudinally spaced positions by applying torque to rotate the lasso 8. To effect the coupling, as shown in the subsequent figures, the lasso 8 acts on a coupling member, such as a collet, within the activation unit 2 that surrounds the wire 4 and is coaxial with the wire. When the lasso 8 is tightened, the collet clamps the wire 4 to transmit ultrasonic energy from an integrated ultrasonic transducer within the activation unit 2, optionally through an amplifier horn coupled to or integrated with the transducer. In some embodiments, the wire 4 can be directly coupled to the transducer, in which case the horn can be omitted.

[0072] The lasso 8 is reversible to release the activation unit 2 from the wire 4. Thus, for different purposes, wires 4 of different sizes, configurations, or materials are provided to be interchangeable. The transducer or horn within the activation unit 2 can also be interchanged.

[0073] Figure 1 An exploded arrangement is shown where the ultrasonic signal generator 10 is separated 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 incorporated into the housing of the activation unit 2. Figure 1The example shown in [Figure 0] has an externally powered ultrasonic signal generator 10 and thus includes a power cable 14 connected to an external power source. Alternative embodiments may be battery powered internally, for example, the internal battery may be incorporated into the ultrasonic signal generator unit 10 or the activation unit 2.

[0074] Generally, the components of the system are preferably portable and more preferably hand-held. These components may be wireless, rechargeable, reusable, and recyclable. Any external cables 12, 14 for transmitting power or signals may be coupled by slip rings to allow the cables 12, 14 to rotate freely and avoid entanglement with the wire 4.

[0075] Now moving on to Figures 2 to 5 , these figures show various arrangements of the activation unit in the longitudinal section. Similar numbers are used for similar features. In each of these examples, the activation unit 2 is externally powered and optionally supplied with ultrasonic signals via a cable 12, although as described above a battery-powered variant is possible.

[0076] Figure 2 It is shown that the housing 18 of the unit 2 contains an ultrasonic transducer 20, which is penetrated by a central port or lumen 22 to allow the passage of the wire 4. The distal portion of the transducer 20 has a threaded section to allow engagement of the collet 24. Various collet concepts will be described later. In this example, the wire 4 extends through the entire length of the transducer 20 and exits proximally from the housing 18. 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 may be made of an elastic material such as a polymer or polymer blend (i.e., compressible and elastic).

[0077] Figure 3 Another embodiment of the present invention is shown, in which an acoustic horn 26 is attached to the distal face of the transducer 20. Acoustic horns such as these acoustic horns can be used to amplify the displacement from the distal face of the transducer 20. For this purpose, the horn 26 may be tapered distally in a continuous tapered configuration or in a stepped configuration as shown.

[0078] In Figure 3 In the example shown, the wire 4 is coupled to the distal end or face of the horn 26 by a collet 24. The horn 26 has a central lumen 22 or channel that is aligned with and communicates with the lumen 22 in the ultrasonic transducer 20. This allows the wire 4 to travel centrally along its common longitudinal axis through the horn 26 and the transducer 20.

[0079] Figure 4 Shown in connection with Figure 2A similar configuration, but in this case, the wire 4 does not travel centrally through the entire length of the ultrasonic transducer 20. Instead, the wire 4 laterally exits 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.

[0080] Accordingly, Figure 5 A configuration similar to Figure 3 is shown, but in this case, the wire 4 does not travel centrally through the entire ultrasonic transducer 20 and the horn 26, but instead laterally exits 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 Figure 4 and 5 , the wire 4 deflects through an acute angle from the central longitudinal axis of the transducer 20 or the horn 26 to laterally exit through one side of the transducer 20 or the horn 26.

[0081] It should be noted that Figures 2 to 5 the arrangement of the present invention illustrated in

[0082] is different from the prior art that uses an electric motor and a cam or a mandrel to drive the wire to vibrate to convert rotational motion into linear motion. 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. This utilizes the piezoelectric effect of the piezoelectric ceramic stack 28, where electrical energy is converted into high-frequency axial linear oscillations.

[0083] Figure 6 An activation unit 2 is shown, similar to the arrangement shown in Figure 2 , which contains an ultrasonic transducer 20 that has a central lumen 22 to allow the direct passage of the wire 4. However, in this case, the distal end of the transducer includes a pneumatic micro chuck 32 to allow the engagement and release of the wire 4. The chuck 32 has angularly spaced jaws, such as three or four jaws, that act directly or through the collet 24 on the wire 4 to grip and release the wire 4 with a constant force.

[0084] Specifically, pneumatic activation of the chuck system presses the chuck 32 against the wire 4 or against the collet 24 disposed around the wire 4 to clamp the wire 4 with the pressure required to couple the ultrasonic energy emitted from the transducer 20. The air line pressure can be used to adjust the force applied by the chuck 32 so as to apply a constant desired clamping force. A solenoid can be used to control the capture and release of the wire 4 to allow longitudinal movement or displacement of the wire 4 relative to the activation unit 2. This allows the wire 4 to be locked in place and overcome possible variations in the regulated air pressure.

[0085] In this example, the compressed air delivery port in communication with the chuck branches to define an auxiliary passage. The auxiliary passage provides a cooling air flow to cool the activation mechanism 2 generally and the coupling area in particular.

[0086] It will be apparent that Figure 6 the principle of the pneumatic chuck 32 shown in can also be applied to arrangements employing an acoustic horn 26 or in which the wire 4 exits the transducer 20 or the horn 26 laterally, such as Figures 3 to 5 those shown in. For the sake of brevity, it should be noted that references to the transducer 20 in this description can refer to the front or distal mass 30 of the transducer 20 or to the acoustic horn 26 attached to the distal face of the transducer, and thus effectively become an integral part of the transducer 20.

[0087] Turning next to Figure 7 of the drawings, the housing 18 of the activation unit 2 is tubular and coaxially surrounds the front mass of the ultrasonic transducer 20. The transducer 20 extends distally near the distal end of the housing. In this example, the wire 4 extends axially along the transducer 20 and passes through the transducer via the central lumen 22, but the wire 4 could alternatively exit the housing 18 laterally as in Figure 4 and 5 . Similarly, the front mass of the transducer 20 could be replaced with an acoustic horn 26 as in Figure 3 and 5 .

[0088] The distal end of the housing 18 is closed by a lasso buckle 8. The lasso buckle 8 can rotate about the central longitudinal axis of the wire 4 and can also be axially pushed in the proximal direction against the distal bias of a spring 42 within the housing 18. The spring 42 can be a discrete spring, such as a helical spring, or can be formed by an elastic forming member such as a helical member attached to and / or integral with the surgical 18 and / or the lasso buckle 8. The lasso buckle 8 is shown here in a distal position biased away from the distal end of the transducer 20 by the spring 42. More generally, the rotation and / or axial movement of the lasso buckle 8 relative to the collet 24 can be guided or determined by a cam or spline forming member.

[0089] The distally open, proximally tapered socket or recess 44 in the distal end of transducer 20 contains a proximally tapered collet 24 that surrounds wire 4 aligned with the inner lumen 22 of transducer 20. The collet 24 has an external thread that engages complementary internal threads in the distal recess of transducer 20.

[0090] The collet 24 is screwed into the recess of transducer 20 and then released by the user manipulating the lasso hitch 8. Specifically, the user first axially pushes the lasso hitch 8 in the proximal direction to engage the collet 24, and then rotates the lasso hitch 8 to advance the collet 24 proximally along the threads within the recess, thereby coupling transducer 20 to wire 4 via collet 24. When released by the user, the lasso hitch 8 springs distally and thus disengages from the collet 24, so as not to interfere with the transmission of ultrasonic energy along wire 4 from transducer 20.

[0091] For this purpose, the distal portion of the collet 24 projects distally from the distal end of transducer 20. When the lasso hitch 8 is pushed proximally against the bias of spring 42, the lasso hitch 8 engages the projecting distal portion of the collet 24 via complementary interface forming members. This engagement between the lasso hitch 8 and the collet 24 allows torque to be transmitted from the lasso hitch 8 to the collet 24, thus advancing the collet 24 proximally along the threads within the recess.

[0092] When the collet 24 is screwed into the recess of transducer 20 in this manner, the complementary proximally tapered surfaces of the collet and the recess cause the collet 24 to grip the wire 4 downwardly in a manner that distributes the gripping force along the wire 4 and avoids point loading. This gripping method, combined with an appropriate choice of material for the collet 24, allows for excellent fit and ultrasonic transmission. The entire assembly of transducer 20 and collet 24 is tuned to obtain an optimal resonant response.

[0093] When wire 4 is to be released from the activation unit 2, the collet 24 can be released by again pressing the lasso hitch 8 proximally to engage it with the collet 24, and then rotating the lasso hitch 8 in the opposite direction to retract the collet 24 distally along the threads in the recess of transducer 20. This relaxes the grip of the collet 24 on the wire 4, thus allowing the wire 4 to be withdrawn from the activation unit 2.

[0094] Optionally, as Figure 7 shown, an internal damper 46 can be positioned at the proximal end of the collet 24. This damper 46 is functionally similar to Figures 2 to 5The damping ring 45 shown therein. In this example, the internal damper 46 is an annular collar made of a superelastic material that surrounds the wire 4 in the inner cavity 22 of the transducer 20. When the collet 24 is screwed into the distal recess of the transducer 20, the damper 46 is axially compressed and radially thickened, thus deforming around the wire 4 and pressing against the wire. The damper 46 thereby damps or attenuates the proximal transmission of the ultrasonic energy imparted by the transducer 20 through the collet 24 to the wire 4.

[0095] Figure 7 An optional internal protective sleeve 48 disposed around the wire 4 within the inner cavity 22 is also shown. The sleeve 48 is made of a low-friction, high-wear-resistant material to center the wire 4 within the inner cavity 22 and shield the wire 4 from the surrounding walls of the transducer 20. The sleeve 48 is preferably made of the same material as the damper 46, which has a damping or attenuating effect on the proximal transmission of the ultrasonic energy applied by the transducer 20 to the wire 4. Similar sleeves 49, 51 can be disposed in the distal portion of the collet 24 and between the lasso buckle 8 and the wire 4 to center and support the wire as the wire 4 projects distally from the collet 24. The sleeve 51 between the lasso buckle 8 and the wire 4 can project 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 lasso buckle 8 are preferably configured to have a damping or attenuating effect on the proximal transmission of the ultrasonic energy imparted to the wire 4.

[0096] Figure 7 Another optional feature shown therein is a torque limiter 50 within the lasso buckle 8 that acts between the outside of the lasso buckle 8 and the collet 24 when the lasso buckle 8 engages the collet 24. If the torque applied by the user to the lasso buckle 8 exceeds a predetermined limit, the torque limiter 50 causes the lasso buckle 8 to slide relative to the collet 24, for example, by deformation of a flexible or elastic interface member of the lasso buckle 8 and / or the collet 24. This prevents the user from overtightening the collet 24 by applying excessive torque to the lasso buckle 8, which could otherwise cause the collet 24 to be overcompressed and thus cause the wire 4 to be subjected to excessive stress and risk of failure.

[0097] Figure 7 The lasso buckle 8 shown therein also includes a strain relief feature, which is illustrated herein by a distally tapered forming member around the wire. This feature alleviates kinking and possible excessive stress of the wire 4 as the wire 4 passes through the lasso buckle 8 and exits the housing 18 of the activation unit 2.

[0098] Figure 8 is shown Figure 7Alternative configurations of the two distal dampers shown herein. Here, the collet-based wire sleeve 49 extends distally from the collet 24 in part, and the lasso buckle-based wire sleeve 51 extends proximally from the lasso buckle 8. The lasso buckle-based wire sleeve 51 can also extend distally from the lasso buckle 8. The proximal end of the lasso buckle-based wire sleeve 51 surrounds and preferably clamps the distal end of the collet-based wire sleeve 49 such that a continuous connection between the two is obtained and the distal damping characteristics of the activation unit 2 are further improved. Alternatively, the distal end of the collet-based wire sleeve 49 can be configured to surround the proximal end of the lasso buckle-based wire sleeve 51, with a similar effect.

[0099] Figure 9 A single-tapered collet 24 is shown, where only the proximal end of the collet 24 is tapered so as to seat in a complementary taper at the base of the distal recess 44 of the transducer 20. Conversely, Figure 10 A double-tapered collet 24 is shown, where the distal end of the collet 24 is also tapered distally.

[0100] The main purpose of the collet 24 used in the present invention is to achieve excellent 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 concert. In particular, the transducer 20 with a coupling interface member optionally including acoustic horns is designed to resonate at the drive frequency of the system.

[0101] The shape and size of the transducer 20 are selected to achieve amplification gain while ensuring that the system remains close to its operating resonance frequency. In addition, any modification to the distal drive face of the transducer 20 to accommodate a connector must be taken into account and considered for the resonance response.

[0102] Figure 9 A transducer 20 fitted with a single-taper external-threaded collet 24 is shown. When torque is applied to the collet 24 to advance the collet 24 into the recess 44, the collet 24 anchors the wire 4 within a complementary threaded hole or recess 44 at the distal end of the transducer 20. The complementary taper at the proximal base of the recess 44 then radially compresses the collet 24 to clamp the wire 4. As Figure 4 shown, when the collet 24 is fully advanced into the recess 44, the distal portion of the collet 24 projects distally from the distal end of the transducer 20. A damper 46 at the proximal end of the recess 44 and a damping sleeve 48 similar to the Figure 7 collet-based sleeve 48 shown are provided for damping or attenuating the proximal transmission of ultrasonic energy imparted by the transducer 20 to the wire 4.

[0103] Figure 10Shown is a transducer 20 equipped with a double - taper collet 24 and a cap screw 54. The proximal cone of the collet 24 is received in a countersunk distal recess 44 in the distal face of the transducer 20. The cap screw 54 similarly receives and is complementary to the cone at the distal end of the collet 24. The torque applied to the cap screw 54 advances the cap screw 54 to longitudinally compress the collet 24 and radially compress the collet 24 to clamp the wire 4.

[0104] As Figure 7 in the arrangement shown, an internal damper 46 is disposed at the proximal end of the collet 24 within the transducer 20. The damper 46 is an annular collar made of a super - elastic material around the wire 4 in the inner cavity 22 of the transducer 20. When the collet 24 is forced proximally into the distal recess 44 of the transducer 20, the damper 46 is axially compressed and radially thickened, thus deforming around the wire 4 and pressing against the wire. The damper 46 thereby damps or attenuates the proximal transmission of ultrasonic energy given by the transducer 20 through the collet 24 to the wire 4. In this arrangement and Figure 7 in the arrangement of, multiple dampers 46 or one longer damper 46 can be deployed along the length within the transducer body 20.

[0105] Figure 11 Shown is an internal damping feature within the housing 18 of the activation unit 2, where the portion of the wire 4 that protrudes proximally from the transducer 20 passes through a series of tortuous bends 94. Guiding the wire 4 through these meandering bends 94 attenuates the ultrasonic energy and thus reduces the proximal transmission. The proximal portion of the wire 4 can also extend through a tube 96 having a high coefficient of friction. In that case, the action of the bends 94 increases the frictional force between the wire 4 and the surrounding tube 96, resulting in 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.

[0106] Additionally, the proximal portion of the wire 4 can slide through a super - elastic tube such as silicone having an inner diameter equal to or less than the outer diameter of the wire. To illustrate the former possibility, Figure 12 and 13 corresponding to Figure 6 the pneumatic clamping arrangement, but shows a damping medium 100 disposed around the wire on the proximal side of the pneumatic micro - chuck 32.

[0107] Similarly, the proximal portion of the wire 4 can be actively clamped or bent off - center by a mechanism independent of or connected to the main user lasso 8. For example, Figure 14 shows how the proximal portion of the wire 4 is captured between offset cams 102 within the activation unit 2. Figure 15Shows a button damping mechanism 104 that can be pressed radially inwards against the proximal portion of the wire 4 within the activation unit 2. The button damping mechanism 104 is configured to apply pressure to the wire 4 and thus damp the displacement of the wire 4.

[0108] In Figure 16a , the housing 18 of the activation unit 2 is fitted at its proximal end with a damping mechanism 105 that includes a proximal cap that can be rotated to bring a laterally offset helical forming member into damped contact with the proximal portion of the wire 4. Figure 16b Shows a cross-sectional view through the damping mechanism 105.

[0109] In Figure 15 and 16a it will be noted that the proximal portion of the wire 4 is surrounded by a strain relief feature extending proximally from the housing 18, which also affects the lateral damping of the wire 4.

[0110] Figure 17 Illustrates how modulation of proximal vibrations can be effected automatically by the user rotating the distal lasso 8. As the lasso 8 is rotated, the guide cable 106 within the housing of the activation unit 2 is displaced. This pulls on a spring-loaded element 108 that acts via a friction collar 110 on the proximal portion of the wire 4, which portion extends through the friction collar. By increasing the friction on the wire 4 and restricting its vibrations, this attenuates the ultrasonic energy otherwise directed proximally from the activation unit 2. In other embodiments, the friction collar 110 can be electronically controlled. A similar distal lasso 8 can then be used to adjust the friction via an electronic coupling between the distal lasso 8 and the friction collar 10.

[0111] Figure 18 Shows another way in which the proximal portion of the wire 4 can be clamped to damp ultrasonic oscillations. Here, the housing 18 of the activation unit 2 supports a rod 112 that extends longitudinally along the housing 18. The proximal end of the rod 112 is biased by a spring 114 into damped contact with the proximal portion of the wire 4. When it is desired to withdraw the wire 4 from the activation unit 2, the distal end of the rod 112 can be depressed to release the pressure exerted by the rod 112 on the proximal portion of the wire 4.

[0112] Damping features can also be incorporated into the collet 24. For example, Figure 19 shows 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 protrusions 76 alternate between opposing portions of the collet 24 to define a undulating path therebetween. The protrusions 76 can be made of a compliant material to effectively damp excitations.

[0113] Figure 20Shows how the lumen of a transducer or horn can be injected with foam or elastomeric polymer material to eliminate movement in the proximal portion of the lead extending proximally from the coupler and from the activation unit.

[0114] Turning next to Figures 21 to 24 , these figures show a safety feature where a rigid tube 176 projecting distally from the distal end of the activation unit 2 surrounds and encapsulates the distal portion of the lead 4. The main purpose of the tube 176 is to prevent the hand-held activation unit 2 from being advanced distally towards the patient during surgery so far that there could be a risk of the lead 4 being lost within the patient's body if the lead 4 breaks. A second benefit of the tube 176 is to provide stress relief and lateral damping for the distal portion of the lead 4.

[0115] In particular, as Figure 22 shown, the tube 176 serves as a spacer to prevent the user from advancing the activation unit 2 all the way into the catheter access port 178, which is commonly referred to in the art as a "luer". The length of the tube 176 imposes a separation distance between the activation unit 2 and the access port 178. As shown, the distal end of the tube 176 can be spherical or otherwise enlarged to serve as an end stop or insertion limiter to prevent the tube from entering the access port.

[0116] The length of the tube 176 ensures that even if the lead 4 breaks, a section of the lead 4 will always remain outside the patient's body. Specifically, if the lead 4 breaks near its point of coupling to the transducer 20 within the activation unit 2, a section of the lead 4 that is at least as long as the tube 176 and typically slightly longer than the tube 176 will always remain outside the access port 178. In this case, the friction between the lead 4 and the tube 176 will help prevent the lead 4 from sliding distally along the tube 176 and into the patient's body.

[0117] Figure 23 and 24 show that the tube 176 can have an additional property of being radially compressible between the user's fingers to clamp the lead 4 within the tube 176 in the event of a break. This helps the user prevent the broken end of the lead 4 from being pulled into the patient's body. The tube 176 can be compressible in this way at its proximal end or at any point along its length, but preferably at or near its distal end, as shown.

[0118] Advantageously, the tube 176 can also be easily detached from the activation unit 2 to allow quick access to the lead 4. For this purpose, the tube 176 can be easily detached 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 lasso buckle 8. There, the tube 176 can be separated from the activation unit 2, for example, by twisting off or a press / pull arrangement.

[0119] Thus, the user can squeeze tube 176 to clamp the broken wire 4, and then, while still clamping wire 4, can pull tube 176 away from activation unit 2 to ensure that wire 4 remains outside the patient's body.

[0120] Now moving on to Figure 25 , this figure shows a flexible tubular protective catheter or sheath 182. At the start of the procedure, sheath 182 extends along or around the distal portion of wire 4, which extends between activation unit 2 and a Luer interface or introducer defining an access port 178 leading into the patient's body. The purpose of sheath 182 is to surround and protect this length of wire 4, which would otherwise be exposed before being advanced into the patient's body. Wire 4 can easily pass through the loose sheath 182, while sheath 182 prevents wire 4 from contacting any material that might contaminate wire 4 or modify, in particular dampen, the oscillations of wire 4.

[0121] Sheath 182 is particularly useful in cases where a long wire 4 has to be inserted into the patient's body, for example to cross an occlusion in the distal tibial artery or a foot artery. In particular, tube 182 helps to insert such a long length of wire 4 in a single continuous movement, rather than intermittently in successive shorter movements, which would occur if activation unit 2 instead repeatedly clamps and releases wire 4.

[0122] Thus, instead of remaining close to introducer 178, activation unit 2 is coupled to wire 4 at a location remote from introducer 178 and is thus ready to introduce the full length of wire 4 into the target vessel. Thus, the user can simply clamp activation unit 2 to wire 4 at a proximal location one meter or more from the patient's body, and then can activate a long section of wire 4 and deliver the long section into the body in a single uninterrupted action.

[0123] Sheath 182 must not impede the distal movement of activation unit 2 and wire 4 towards introducer 178. Thus, when activation unit 2 and wire 4 are advanced distally, sheath 182 can collapse along its length or in a hexagonal concertina. In another method, as shown here, sheath 182 has longitudinal slits 184, groovezippers or other closures along its length to separate longitudinally and then peel away from wire 4 to provide clearance as activation unit 2 and wire 4 are advanced distally together through sheath 182.

[0124] In Figure 26In [reference], the displacement or movement of the proximal end of the wire 4 is reduced by a flexible tubular sleeve 71 that surrounds the proximal portion of the wire 4, where the wire exits the housing 18 of the activation unit 2 at the proximal portion. This flexible tubular sleeve, made of, for example, an elastic polymeric material, abuts against the wire 4 and thereby damps its movement.

[0125] Figure 27 A similar embodiment of the activation unit 2 is shown. In addition to what has been shown in Figure 26 , this embodiment further includes a clamp 72 that presses the flexible tubular sleeve 71 onto the wire 71. The clamp 72 can be longitudinally movable along the sleeve 71 to a position that produces an optimal damping effect. In Figure 28 , the clamp 72 is replaced by a collet 73, which can also move along the sleeve 71. Additionally, the collet 73 can be adapted to control the clamping force by which it clamps the tubular sleeve 71 and the wire 4 extending therethrough. The double collet 73 provides a damping characteristic that compresses the wire in the axial or longitudinal direction and can clamp the wire 4 at more than one point. In another embodiment, Figure 27 's clamp 72 and Figure 28 's collet 73 can be combined.

[0126] In Figure 29 , the activation unit 2 includes a proximal twist lock 74 that clamps onto the proximal portion of the wire 4 and couples the wire to the housing 18 of the activation unit 2 to damp the displacement or movement of the proximal portion of the wire 4. The proximal twist lock 74 can include a collet 74a or a tubular sleeve that surrounds the wire 4 and is tightened by operating the proximal twist lock 74. In addition to this, the activation unit 2 can include a similar distal twist lock 75 having a collet 75a that couples the transducer to the distal portion of the wire 4. Each or both of the twist locks 74, 75, but preferably at least the distal twist lock 75, can be combined with a user lasso buckle 8 as disclosed in Figure 1 and in many other figures discussed above. Such a user lasso buckle 8 will then be configured to be rotatable about the same longitudinal axis independently of the twist locks 74, 75. Another mechanism or operator can place the wire 4 in a tensioned or compressed state before locking, or the wire 4 can remain neutral before locking.

[0127] Figure 30a , 30b and 30c show three different arrangements of a wire retaining formation 76 that can be provided inside the housing 18 of the activation unit 2, preferably at least at its proximal end, in order to firmly hold the wire 4 and thereby attenuate the displacement or movement of its proximal portion. As in Figure 19As already shown, these wire retaining formations 76 may be disposed inside the collet 24, or in any other element surrounding the wire 4 and rigidly mounted inside the housing 18. The wire retaining formation 76 may be spring-biased against the proximal portion of the wire 4 and damp the vibration of the proximal portion. In Figure 30a four wire retaining formations 76 together provide two contact points with the wire 4. In Figure 30b three wire retaining formations 76 provide three contact points. In Figure 30c three wire retaining formations 76 are arranged such that the wire 4 takes a meandering path through longitudinally staggered contact points, similar to the path shown in Figure 19 The combinations and variations of the arrangements shown in Figure 30a and 30b and 30c will be obvious to those skilled in the art. It should be further noted that similar arrangements may be used for the lateral pins 98 in the embodiments of Figure 11 .

[0128] In Figure 31 an elastic plug 77 or grommet is provided which may be pushed into the proximal end of the central port 22 extending through the housing 18 and against the proximal portion of the wire 4 extending therethrough. The plug 77 is designed to fit tightly into 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 similarly moldable and / or elastic material. Pushing the plug 77 into the central port 22 will cause the elastic plug 77 to be compressed and the wire 4 to be clamped, thereby further damping the lateral movement of the proximal portion of the wire 4.

[0129] In Figure 32 a tubular flexible membrane 78 is disposed within the central port 22 of the housing 18. The tubular flexible membrane 78 defines an annular cavity which may be inflated or filled by applying fluid pressure through a port 79 in the housing 18 which communicates with the cavity. The port 79 may be connected to an external fluid reservoir and a pump may pump fluid into the tubular flexible membrane 78 to radially press the membrane 78 inwardly against the proximal portion of the wire 4 to damp the vibration of this portion of the wire 4. When the fluid pressure is released, the flexible membrane 78 is deflated and the central port 22 is opened again, thereby allowing the wire 4 to move relative to the activation unit 2 for adjustment, insertion or removal of the wire 4. The fluid may be any type of liquid, such as water. Alternatively, the fluid may be air, in which case the membrane 78 is pneumatically operated. Although the port 79 shown in Figure 32 is arranged to be connected to an external fluid reservoir, alternative embodiments may use a fluid reservoir integrated within the housing 18.

[0130] Most of the embodiments described above illustrate measures for damping movement in the proximal end of the wire 4, mainly for the safety of the user and to avoid damage to expensive and sensitive equipment and indeed the wire itself. However, it may also be desirable to damp certain wire movements at the distal end of the activation unit 2. Appropriate distal damping increases the efficiency and efficacy of the intravascular device by transferring energy from the transducer to the active distal tip portion of the wire 4 mainly through longitudinal waves, without unnecessary loss of energy due to lateral movement of the wire 4 along the way.

[0131] Figure 33 FIG. shows one way in which distal damping of the wire 4 can be achieved. In this figure, a thin sheath 81 surrounds the portion of the wire 4 that protrudes from the distal end of the housing 18 of the activation unit 2 to damp the lateral vibrations 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 implemented as a coating on the wire 4, such as a painted layer.

[0132] Figure 34a 、 34b and 34c provide three variants of a catheter or sheath configured to provide proximal and / or distal damping. Each of these sheaths can be a discrete sleeve as discussed with reference to Figure 33 . Such discrete sleeves can be fitted tightly or loosely around the wire 4. Alternatively, the sheath can be coated or painted onto the wire 4. The sheath, sleeve or coating can be a continuous sheath 82 as shown in Figure 34a , a helical or spiral sheath 83 as shown in Figure 34b or a discontinuous or stepped sheath 84 as shown in Figure 34c . The sheath can have cut-out windows along its length. Thus, selective or intermittent damping can be achieved by selectively or intermittently covering or surrounding the wire 4. Intermittent covering may result in discrete sections with an outer diameter larger than the outer diameter of the wire.

[0133] All of the sheaths 82, 83, 84 have the effect of increasing the weight and inertia of the wire 4 and thereby restricting the movement of the covered portion of the wire 4. If the displacement of the wire 4 is greatest at a position coinciding with the damping wall section of the discontinuous or windowed sheath, this can have a positive effect on the damped movement of the wire 4, as shown in Figure 34c .

[0134] The sheath may be thinner at its distal end than at its proximal end, such that the distal portion of the wire 4 is allowed to be fitted within the catheter that supports the wire 4. To maintain the possibility of the activation unit 2 translating along the wire, the sheath at the proximal end may be movable along the wire 4. Alternatively, a section of the sheath is configured to be removable when needed. In one embodiment, the same coated or painted sheath may be provided along the entire wire 4, with only an additional removable or movable sheath at the proximal end.

[0135] Figure 35a and 35b A variant of the distal damping mechanism is shown, in which the rod 85 is pivotable relative to the housing 18 against the wire 4 that projects distally from the acoustic horn 26 of the transducer 20 within the housing. The rod 85 bears against a portion of the wire 4 within the housing 18 that is disposed between the horn 26 and the distal end of the housing 18. The strain relief feature around the wire 4 extends distally from this end of the housing 18. The rod 85 may bear directly against the wire 4 as shown in Figure 35a or indirectly against the wire through an intermediate pad 86 inserted between the rod 85 and the wire 4 as shown in Figure 35b .

[0136] It should be noted that many of the features of the various embodiments described above are not limited to those specific embodiments. A person skilled in the art will be able to combine the features from one embodiment with the features of other embodiments, provided that this is technically possible and makes sense from a practical perspective.

Claims

1. An intravascular device for crossing an obstruction in a blood vessel, the device comprising: An elongate intravascular element; A source of ultrasonic energy, including an ultrasonic transducer in a transducer housing, A coupler for transmitting the ultrasonic energy from the source to an active tip portion at the distal end of the intravascular element along the intravascular element in use, the coupler being arranged to couple the source to the intravascular element at any of a plurality of discrete operating positions along the length of the intravascular element for the transmission of the ultrasonic energy to the active tip portion, the coupler being further arranged to clamp the intravascular element when at any of the operating positions, the intravascular element extending through the coupler and the source and having portions extending proximally and distally from the coupler and the source respectively, Wherein the intravascular device further comprises a damping feature mechanically coupled to the intravascular element to attenuate lateral displacement of the intravascular element at a position proximal and / or distal to the distal tip portion of the ultrasonic transducer and away from the distal tip portion.

2. The intravascular device according to claim 1, wherein the damping feature is also mechanically coupled to the intravascular element to attenuate longitudinal displacement of the intravascular element proximal to the ultrasonic transducer.

3. The intravascular device according to claim 1 or 2, wherein the transducer housing further comprises at least one of the damping features.

4. The intravascular device according to claim 3, wherein at least one of the damping features is mechanically coupled to the intravascular element external to the transducer housing.

5. The intravascular device according to claim 1 or 2, wherein the ultrasonic transducer comprises a lumen for holding the intravascular element, and the damping feature comprises at least one damping ring or damping sleeve made of an elastic material disposed between the intravascular element and the inner surface of the lumen.

6. The intravascular device according to claim 1 or 2, wherein the transducer housing comprises a distal opening through which the intravascular element extends, and wherein the damping feature comprises a damping ring or damping sleeve disposed between the intravascular element and the inner surface of the distal opening.

7. The intravascular device according to claim 1 or 2, wherein the damping feature comprises a plurality of guiding formations disposed in the transducer housing and arranged to be in direct contact with opposite sides of the intravascular element to prevent lateral movement of the intravascular element in a direction perpendicular to the intravascular element itself.

8. The intravascular device according to claim 1 or 2, further comprising a rigid tube disposed distally of the transducer housing and surrounding the intravascular element.

9. The intravascular device according to claim 1 or 2, wherein the damping feature includes a flexible and elastic tubular sleeve disposed at least partially proximal to the transducer housing, the flexible and elastic tubular sleeve surrounding and holding a portion of the intravascular element, and wherein the damping feature further includes an adjustable clamp for selectively clamping a portion of the flexible and elastic tubular sleeve.

10. The intravascular device according to claim 1 or 2, wherein the damping feature includes a pair of two rotatably adjustable offset cams for clamping the intravascular element therebetween, the offset cams being disposed inside the transducer housing, proximal to the transducer.

11. The intravascular device according to claim 1 or 2, wherein the damping feature includes a button damping mechanism capable of pressing radially inward against the intravascular element, the button damping mechanism being disposed inside the transducer housing, proximal to the transducer.

12. The intravascular device according to claim 1 or 2, wherein the damping feature includes a rotatably adjustable proximal cap capable of being rotated to bring a laterally offset helical forming member into damped contact with the intravascular element, the rotatably adjustable proximal cap being disposed inside the transducer housing, proximal to the transducer.

13. The intravascular device according to claim 1 or 2, wherein the damping feature includes a controllable friction collar surrounding the intravascular element for applying an adjustable frictional force thereto, the controllable friction collar being disposed inside the transducer housing, proximal to the transducer.

14. The intravascular device according to claim 1 or 2, wherein the damping feature includes a rod extending longitudinally along the transducer housing, the rod being spring-biased into damped contact with the intravascular element at a position proximal to the transducer.

15. The intravascular device according to claim 1 or 2, wherein the transducer housing further includes a rotatable twist lock surrounding the intravascular element and configured to apply an adjustable clamping force to the intravascular element.

16. The intravascular device according to claim 1 or 2, wherein the damping feature includes a grommet surrounding the intravascular element at a position proximal to the transducer housing and configured to fit into a proximal opening of the transducer housing.

17. The intravascular device according to claim 1 or 2, further comprising a collet surrounding the intravascular element, the proximal end of the collet being removably coupled to the ultrasonic transducer, and the damping feature including a damping ring or a damping sleeve disposed around the intravascular element and within the distal end of the collet.

18. The intravascular device according to any one of the preceding claims 1 or 2, wherein the damping feature includes a sheath and / or a coating surrounding at least a portion of the intravascular element distal to the transducer.

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