Intravascular device for passing through obstruction in blood vessel

Abstract

To provide an intravascular device capable of maximizing the displacement amplitude at a distal tip of a wire to excavate a lesion, and minimizing displacement or movement of a proximal portion extending both in the distal direction and the proximal direction from an actuation unit.SOLUTION: An intravascular device comprises: an elongated intravascular element such as a wire 4 which includes a proximal section, a distal tip section having a smaller diameter than the proximal section, and an intermediate section tapering distally and extending between the proximal section and the distal tip section; an ultrasonic transducer which is mechanically coupled to the proximal section of the elongated intravascular element to ultrasonically actuate the elongated intravascular element, thereby exciting the distal tip section to facilitate passage through an obstruction; and a tube which surrounds the elongated intravascular element, and extends distally from an actuation unit 2 that houses the ultrasonic transducer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the treatment of ischemia by using an ultrasonically actuated wire to cross blockages within blood vessels and, optionally, to facilitate the introduction of subsequent treatment devices.

[0002] The present invention develops concepts expressed in our PCT / EP2019 / 080449 (published as WO 2020 / 094747), PCT / EP2020 / 081386, and PCT / EP2020 / 081399 (both soon to be published), the contents of which are incorporated herein by reference.

[0003] As explained in these applications, ischemia is an inadequate blood supply to organs in the body. In atherosclerotic blood vessels, ischemia occurs as a result of a blood vessel being blocked by an obstruction resulting from a lesion in the vessel wall, an atherosclerotic plaque, or an embolus resulting from other causes. Atherosclerotic plaque is composed of material whose structure gradually hardens over time. By partially or completely obstructing a blood vessel, the blockage restricts blood flow to tissues distal to the blockage, causing cell death and a rapid deterioration in tissue health.

[0004] The preferred method for treating such blockages is through minimally invasive endovascular angioplasty. In these procedures, small-diameter therapeutic devices are introduced into the vascular system, navigated through the lumens of veins and arteries to the blockage, and deployed at the lesion site to restore patency. These procedures, which revascularize blockages in coronary and peripheral arteries in the treatment of chronic atherosclerotic plaques, can also be used to treat acute embolic blockages, thrombi, occlusive clots, or chronic total occlusions (CTOs).

[0005] The anatomical structures in which these procedures are performed include, but are not limited to, the coronary arteries, neurovascular arteries, and peripheral arteries, including those supplying the lower extremities. Different anatomical structures are associated with different pathologies. The pathologies found in the various peripheral vessels pose different types of challenges than those found in the coronary arteries. The iliac, femoral, popliteal, and infrapopliteal arteries vary in tortuosity and are often substantially smaller than the coronary or neurovascular systems. However, these arteries are susceptible to extensive calcification, which poses serious obstacles to the success of endovascular procedures.

[0006] 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 trauma to the tissue and patient can be minimized.

[0007] In peripheral arterial revascularization procedures, access is often achieved through surgical cutdown and puncture of the femoral, popliteal, and 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 in place. The sheath serves as a port for device introduction, withdrawal, and exchange, minimizing arterial tissue ablation. A guide catheter and guidewire are then introduced into the artery to provide additional protection and aid in device navigation to the target site.

[0008] 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 occlusion.

[0009] Guidewires are used in other minimally invasive procedures to introduce other devices and instruments into vessels or other cavities within the body to enable examination, diagnosis, and different types of treatment. Guidewires are used, for example, in balloon angioplasty, gastrointestinal procedures, urological procedures, and gynecological procedures. All such procedures require a passageway to be formed through an obstruction to facilitate passage of a larger diagnostic or therapeutic device to the site of a lesion or other tissue targeted within the body distal to the lesion.

[0010] Visualization of the progress of guidewires and other devices advanced through the anatomy is typically accomplished by x-ray or duplex ultrasound, with MRI becoming increasingly common in other anatomy.

[0011] Guidewires are manufactured from a variety of materials with many different designs, most typically stainless steel and various alloys including NiTi (nitinol). As an example, the wire may be tapered along its length to create varying degrees of flexibility along its length. Thus, at its distal end, the wire has sufficient flexibility to conform to the shape of the vessel and strength to transmit force to the tip ("tip stiffness") or force to pass through the lesion.

[0012] Wires are available in a variety of outer diameters related to the anatomy being treated. Wires on the order of 0.010 inches (approximately 0.25 mm) in diameter are commonly used in the neurovascular system, while wires with an outer diameter of 0.014 inches (approximately 0.36 mm) are typically used in coronary applications. Such wires are also used in many peripheral vasculature, typically in the anatomy of the leg and tibial fossa below the popliteal fossa. When accessing and treating large, straight diseased vessels, such as the iliac, aortic, and thoracic vessels, wires with a typical outer diameter of 0.035 inches (approximately 0.89 mm) may be used. Wires with a diameter of 0.018 inches (approximately 0.46 mm) can be used in the lower leg.

[0013] The length of wires used in endovascular procedures also varies depending on the distance they are likely to operate over. As an example, wires ranging in length from 750 mm up to 900 mm are typically used in many peripheral applications where they can be introduced into the femoral or popliteal anatomy or must be tracked to and through blockages in the ipsilateral iliofemoral and infrapopliteal arteries. Wires used in contralateral and coronary applications tend to be on the order of 1200 mm, 1500 mm, or 1700 mm in length. In fact, wires that can be tracked contralaterally can be much longer, perhaps on the order of 2000 mm to 2250 mm, 2500 mm, or even 3000 mm or longer.

[0014] In some cases, elongated wires may be used to facilitate the deployment of certain treatment devices, in which case the proximal end of the wire may require certain features.

[0015] Many conventional intravascular wires are passive mechanical devices with no active components. Passive wires do not transmit any energy other than that applied by the clinician. They are manipulated by pushing, pulling, or torquing their proximal ends to navigate to the blockage site and then pushed through or around the blockage. However, very often, the blockage is too difficult for conventional wires to pass. These passive wires either do not function as intended as guidewires or are limited when attempting to cross near- or completely blocked blockages that may be heavily calcified. In situations where the wire tracks around the blockage, e.g., in subintimal situations, such wires often fail to re-enter the true lumen.

[0016] The present invention relates to the use of ultrasonic vibrations transmitted along a wire to cross obstructions. The transmission of ultrasonic vibrations along a small diameter catheter and assembly is disclosed in U.S. Patent No. 3,433,226. U.S. Patent No. 5,971,949 describes the transmission of ultrasonic energy through waveguides of different configurations and tip geometries. U.S. Patent No. 5,427,118 describes an ultrasonic guidewire system but does not discuss in detail the proximal geometry of the wire or how to facilitate subsequent devices via an over-the-wire approach.

[0017] Many current single transducer systems are not ultrasonically actuated guidewires, but instead are ultrasonically actuated catheters that include a wire member for agitating and ablating 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 thus the separate guidewires are tools to facilitate crossing blockages. U.S. Patent No. 9,629,643 shows systems with a range of distal tip configurations, but all require a separate guidewire for access.

[0018] These ultrasonically actuated devices are directed to delivering alternative methods of revascularization and are often described as atherectomy devices, pass-through devices, or angioplasty devices. In the art, these devices and recanalization wire devices provide or perform atherectomy by enhancing revascularization and reducing the bulk of the lesion by removing the plaque that forms the lesion.

[0019] Ultrasound-activated catheter and wire systems have been considered in the past as a method of atherectomy and for preparing blood vessels for angioplasty treatment. Some products have been commercially available in the past, some are still available, and some 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 electricity 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.

[0020] A small diameter wire or waveguide, serving as a wave delivery system, ultrasound delivery system, or transmission member, is coupled to the transducer directly or through an optional horn to transmit 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 for the purpose of excavating material and ultimately facilitating revascularization or recanalization of blood vessels and anatomical structures throughout the body. Tissue and material near the distal tip are affected by a combination of the ultrasonic motion of the tip, its direct mechanical abrasion, ablation, and cavitation from pressure wave components, and acoustic streaming, which removes the ablated material from the zone around the tip. [Prior art documents] [Patent documents]

[0021] [Patent Document 1] U.S. Patent No. 3,433,226 [Patent Document 2] U.S. Patent No. 5,971,949 [Patent Document 3] U.S. Patent No. 5,427,118 [Patent Document 4] U.S. Patent No. 6,855,123 [Patent Document 5] U.S. Patent No. 4,979,939 [Patent Document 6] U.S. Patent No. 9,629,643 [Patent Document 7] International Publication No. 2020 / 094747 Summary of the Invention [Problem to be solved by the invention]

[0022] Generally speaking, the devices of the present invention use a handheld actuation unit and intravascular wire combination to transmit ultrasonic vibrations to the distal tip of the wire for the purpose of passing through blockages that impede blood flow, such as chronic total occlusions and other complex lesions. The actuation unit houses an ultrasonic transducer and a mating collet having a central lumen through the transducer and collet to allow passage of the intravascular wire. In such a configuration, the actuation units can be slid over the intravascular wire and can be mated to each other at multiple locations along the wire.

[0023] Once coupled to the wire, the actuation unit transmits ultrasonic energy through the wire and can subsequently be deactivated, moved to another location on the wire, coupled, and reactivated. The actuation unit can then be detached from the wire and completely removed, for example by sliding it proximally over the wire, while the wire remains in place, allowing for subsequent treatment. However, the device can also be used in stand-alone treatments to effect revascularization and restore blood flow in foot applications or otherwise.

[0024] In known ultrasonically activated intravascular wire or catheter systems, the proximal end of a guidewire is connected to a transducer. In our patent application published as WO 2020 / 094747, the wire extends through the transducer and extends proximally as well as distally from the transducer. This allows a user to couple the transducer to the wire at any desired location and adjust the overall length of the distal portion of the wire from the transducer to the distal tip without having to cut the wire.

[0025] An adjustable overall length of the distal portion of the wire can be very useful for practical purposes, for example to accommodate the expected length of the trajectory that the wire tip will need to travel within the patient's body. Also, control of the wire is enhanced in maintaining its position within the vessel lumen while adjusting or reconnecting the activation source. Additionally, the adjustable length distal portion of the wire helps to achieve and optimize resonance at the distal tip at any desired frequency.

[0026] When ultrasonic energy is used to excite the wire, it is desirable to maximize the displacement amplitude at the distal tip of the wire to excavate the lesion, and to minimize displacement or movement of the proximal portion of the wire that remains outside the patient's body and extends both distally and proximally from the actuation unit. [Means for solving the problem]

[0027] In one respect, the present invention relates to an intravascular device for passing an obstruction in a blood vessel, the device comprising: an elongated intravascular element, such as a wire, the elongated intravascular element having a proximal section, a distal tip section having a smaller diameter than the proximal section, and a distally tapering intermediate section extending between the proximal and distal tip sections; an ultrasonic transducer mechanically coupled to the proximal section of the element for ultrasonically actuating the element, thereby exciting the distal tip section to facilitate passage through the obstruction; and a catheter surrounding the element, wherein at least a portion of a distal tip portion of the element protrudes distally beyond the distal end of the catheter.

[0028] The catheter may be longitudinally movable relative to the activated element to adjust the protrusion length of the distal tip section. The catheter may also have an adjustable diameter lumen that defines a variable radial gap around the element. For example, the catheter may include an inner distal collar, such as an annular inner balloon, that is expandable radially inward toward the element.

[0029] The catheter may also include an external distal centering device extendable in a radially outward direction from at least two opposing sides of the catheter, which may also employ at least one external balloon. Similarly, the catheter may include an external steering arrangement extendable from the catheter in at least one radially outward direction to deflect the distal end and elements of the catheter laterally from the longitudinal axis.

[0030] The catheter may include at least one radially self-expanding cage-like stent or support deployable from the catheter around the element and having a longitudinally tapered shape when deployed.

[0031] The proximal end of the catheter may be coupled to the transducer to receive ultrasonic energy from the transducer. For example, the catheter may be coupled to the transducer over a transmission path that bypasses the collet that couples the element to the transducer. Alternatively, the catheter may be coupled to the transducer over a transmission path that extends through the collet that couples the element to the transducer. One or more waveguides may extend along the catheter.

[0032] Conveniently, the catheter comprises a longitudinal slit extending along at least the majority of the length of the catheter, the slit communicating with the lumen of the catheter for accommodating the element. Such a slit may terminate short of the distal end of the catheter.

[0033] The catheter may define at least two parallel lumens, a first of which is for housing an element and a second of which is in communication with a fitting for connection to a pump for driving fluid flow along the second lumen or for pressurizing fluid in the second lumen. The second lumen may be in fluid communication with the first lumen.

[0034] Correspondingly, the concept of the present invention encompasses an intravascular device for passing through an obstacle in a blood vessel, comprising: an elongated intravascular element, such as a wire, having a proximal section, a distal tip section having a smaller diameter than the proximal section, and a distally tapering intermediate section extending between the proximal and distal tip sections; an ultrasonic transducer mechanically coupled to the proximal section of the element for ultrasonically actuating the element, thereby exciting the distal tip section to facilitate passing through the obstacle; and a tube surrounding the element, the tube extending distally from an actuation unit housing the transducer.

[0035] At least a portion of the tube may have a structure that is more rigid laterally than longitudinally. For example, the tube may be longitudinally stretchable and collapsible. Conversely, a portion of the tube may have a structure that is more rigid longitudinally than transversely. For example, that portion of the tube may be user-compressible radially inward to contact an element.

[0036] The inventive concept also encompasses a method of passing through an obstruction in a blood vessel. In one expression, the method includes actuating a distal tip section of a wire with ultrasonic energy and moving the distal tip section in a first order longitudinal mode with distal and proximal vibrations, and also in a radial direction with a transverse mode and a differential harmonic second order mode. Alternatively expressed, a method for passing through an obstruction in a blood vessel, the method including exciting a distal tip section of an elongated intravascular element, such as a wire, by transmitting ultrasonic energy from a wider proximal section of the element along a distally tapering intermediate section of the element to the distal tip section, the excitation producing transverse subharmonic vibrations in the distal tip section in addition to longitudinal vibrations driven by longitudinal resonance in the element.

[0037] Advantageously, the distal tip section undergoes orbital or multi-harmonic motion about the central longitudinal axis to excavate a tunnel in the obstruction that is substantially wider than the distal tip section. For example, the distal tip section of the element can be advanced distally through the obstruction to form an aperture, followed by inducing orbital and / or multi-harmonic motion in the distal tip section distal to the obstruction and moving the orbital or multi-harmonic distal tip section proximally through the obstruction to widen the aperture.

[0038] The element may be supported within the peripheral catheter, leaving at least a portion of the distal tip section protruding distally beyond the distal end of the catheter. Relative longitudinal movement between the element and the catheter enables the catheter to induce orbital and / or multi-harmonic motion in the distal tip section proximal to the obstruction, and subsequently move the orbital or multi-harmonic distal tip section distally through the obstruction to form or widen an aperture through the obstruction.

[0039] The centering force is applied by at least one inflatable balloon, and the method may include inflating the balloon to center the catheter before using the element to pass through the obstruction, advancing the balloon into an aperture in the obstruction, and re-inflating the balloon within the aperture.

[0040] The present invention extends to various methods of manipulating an elongated intravascular element, such as a wire, for passing an obstruction within a patient's blood vessel. One such method includes advancing an actuation unit distally toward the patient's body, the actuation unit being coupled to and ultrasonically actuated by the element, and limiting the distal advancement of the actuation unit toward the body with a tube extending distally from the actuation unit and surrounding a portion of the element, keeping that portion of the element outside the body.

[0041] Another such method includes supporting a portion of the element outside the patient's body in a tube extending distally from an actuation unit coupled to the element for ultrasonically actuating the element, and forcing a portion of the tube radially inward into contact with the element. Conveniently, the tube can be removed from the actuation unit while continuing to grip the element by depressing a portion of the tube.

[0042] Another such method includes supporting a portion of the element outside the patient's body in a tube extending distally from an actuation unit coupled to the element for ultrasonically actuating the element, and varying the length of the tube by applying a longitudinal force to a telescoping, bellows, or braided structure of the tube.

[0043] Another such method includes supporting a portion of the element outside the patient's body within a tube extending between the body and an actuation unit coupled to the element and ultrasonically actuating the element, the wall of the tube being pierced by a longitudinal slit, and either prior to inserting at least a portion of the portion of the element into the tube through the slit or subsequently withdrawing at least a portion of the portion of the element through the slit and out of the tube, the slit terminating short of a distal end of the tube, such that the element is constrained within the distal portion of the tube.

[0044] If the element is supported within a first lumen around the catheter, fluid may be driven from a second lumen of the catheter into the first lumen around the element. In another approach, fluid may be driven along the second lumen of the catheter to aspirate debris dislodged from the obstruction by excitation of the distal tip section of the element.

[0045] As a result of ultrasonic activation, the motion in the distal tapered region of the wire consists of both axial and radial or lateral components, where the axial component is driven by the longitudinal displacement in the transducer at the driving frequency, while the radial component consists of a series of transverse modes whose magnitude and shape (amplitude and frequency) are determined by the geometry and flexibility of the wire, the dimensions of the transition region, and the geometry of the distal section of the wire.

[0046] These wire design features, which determine its flexibility and allow it to express lateral displacement, are selected to promote coupling at subharmonic frequencies of the drive frequency. As a result, the wire geometry in the distal region can be optimized to drill, abrade, or cut primarily axially, or to have more significant lateral movement in addition to axial or longitudinal movement. The use of both axial and radial movement in the distal region helps increase the opening profile during drilling and for subsequent procedures thereafter.

[0047] In a preferred embodiment, the system of the present invention includes a signal power generator, an ultrasonic transducer, an optional acoustic horn, a transmission waveguide or traversing wire capable of transmitting high frequency ultrasonic vibrations to its distal tip to ablate through non-compliant and other materials blocking the artery and sized to facilitate delivery of standard diagnostic and therapeutic devices, and a coupling, an attachment mechanism that couples the transmission wire to the acoustic horn or directly to the transducer, minimizing losses and allowing faithful transmission of high frequency mechanical energy.

[0048] The systems of the present invention may or may not be handheld to control the operation of a medical device and may include a compact housing unit that houses all or some of the following components: a signal generator, an ultrasound transducer, an acoustic amplification horn (the horn may be part of the transducer assembly or may be omitted), and interface coupling components, as well as data acquisition, processing, and system control. In some embodiments, all of these components are integrated into a single unit. In other embodiments, the components are separated and the generator is housed separately. In another embodiment, the transducer horn is separate. In another embodiment, a fitting connects directly to the transducer stack.

[0049] A set, type, or series of interchangeable flexible transmission member assemblies or crossing guidewires are provided for minimally invasive percutaneous surgical recanalization of blocked or partially blocked anatomical passageways. Couplings allow the crossing wires to be connected to an ultrasound transducer and / or horn assembly.

[0050] In use, a signal generator supplies electrical energy to the transducer, the piezoelectric ultrasonic transducer converts the electrical energy into mechanical vibrations, which may be further amplified by an acoustic horn, a transmission member is coupled to the acoustic transducer or horn, the ultrasonic vibrations are transmitted through the transmission member, and the distal tip of the transmission member vibrates at a predetermined frequency and amplitude with the ability to beneficially destroy diseased tissue or other material. The ultrasonic transducer may be controlled by a suitable controller to achieve a constant vibration amplitude.

[0051] The ultrasound generator, main housing, circuitry, and coupling components remain outside the patient's body. The majority of the length of the transmission member and any peripheral catheter components are the only portions of the system that need to enter the patient's body. The proximal section of the transmission member and any peripheral catheter components remain external to facilitate coupling to the main unit and the steering and control procedure requirements.

[0052] In a preferred method of operation, the intravascular traversing wire can be initially used within the anatomical passage in a passive mode without ultrasonic vibration. While the wire remains within the anatomical passage, the traversing wire can be optionally coupled to an acoustic horn / transducer assembly located within the housing to energize or transmit ultrasonic vibrations through the wire, which acts as a transmission member. This results in vibrations at the distal tip, resulting in lesion traversal.

[0053] Following ultrasonic activation, the transverse wire can be decoupled or decoupled from the acoustic horn located within the housing, as needed, to return to a passive wire configuration to facilitate further subsequent devices or treatments.

[0054] The ultrasonic transducer, horn, coupling means, signal generator, power supply, and control circuitry can all be located in the same hand-carried, lightweight, compact housing unit. In another embodiment, the signal generator is separate and is joined via a connector cable to the compact housing unit containing the transducer and horn. In another embodiment, the entire system can be designed as a disposable device, hi another embodiment, the ultrasonic transducer, horn, coupling means, generator, and control circuitry can all be located in the same portable, compact housing unit and connected to a power source via a cable.

[0055] Distal features can be included to improve navigation and passage performance, including optimized wire control and steerability for tracking through anatomy, and to increase the aperture profile achieved. Additionally, marker bands can be included to provide visibility under fluoroscopy or x-ray. Radiopaque markers may indicate, for example, the working length and transverse tip of the wire.

[0056] The device may operate at a set or variable frequency, for example, between 20 kHz and 60 kHz, preferably between 35 kHz and 45 kHz, more preferably between 37 kHz and 43 kHz, and most preferably about 40 kHz. The device may also operate at a desired low power, for example, in the range of 1 W to 5 W, or up to 3 W, 10 W, or 15 W. In addition to automatic control over a desired low power range, for example, between 1 W and 5 W, the device's output can be controlled to allow the user to boost power beyond this range, thus compensating for unexpected interference and ensuring fast, effective traversal. Thus, the device can also deliver higher power levels, for example, up to 50 W to 100 W maximum load, to aggressively traverse difficult lesions and overcome tip attenuation or deflection.

[0057] The intravascular device of the present invention allows for energy-efficient maximization of the displacement amplitude at the distal tip of the wire. For optimal efficiency, it is important that the majority of the power provided by the transducer is transmitted to the distal tip by longitudinal waves passing through the wire. Thus, energy loss due to transverse vibration of the wire is minimized. It is also desirable to improve the resistance of the wire to breakage.

[0058] Damping the longitudinal and lateral movement of the proximal portion of the intravascular wire outside the patient minimizes displacement or migration of the proximal portion of the wire. Reducing unwanted 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.

[0059] A wire is one example of an elongated intravascular element that can be used as a waveguide or wave delivery system. For example, the element may be a hybrid between a wire and a catheter. In particular, the proximal portion of the element, e.g., approximately the first meter of the element from the proximal end, may have an encapsulated wire in a manner similar to a catheter, 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 may be an internal component of an overall wave delivery system. [Brief explanation of the drawings]

[0060] In order that the present invention may be more readily understood, reference will now be made, by way of example, to the accompanying drawings in which: [Figure 1] 1 is a perspective view of an apparatus of the present invention; [Figure 2] FIG. 1 is a side view of an active wire of the present invention. [Figure 3] FIG. 1 is a detailed side view of an active wire of the present invention protruding distally from a catheter. [Figure 4] 10A-10C are a series of images showing an active wire excavating a tunnel within a lesion that was blocking a blood vessel. [Figure 5] 10A-10C are a series of diagrams showing an active wire tunneling a lesion. [Figure 6] 10A-10C are a series of diagrams showing an active wire tunneling a lesion. [Figure 7] 10A-10C are a series of diagrams showing an active wire tunneling a lesion. [Figure 8] FIG. 1 is a side view of a longitudinal section of an active wire and catheter coupled to an actuation unit. [Figure 9] 10 shows the centering feature of the present invention being used for centering to drill a lesion and then for angioplasty of the lesion after drilling. [Figure 10] 10 shows the centering feature of the present invention being used for centering to drill a lesion and then for angioplasty of the lesion after drilling. [Figure 11]1 illustrates the steering feature of the present invention. [Figure 12] 10 shows a mechanism for varying the lumen of the catheter around the active wire. [Figure 13] 10 shows an alternative wire and catheter placement. [Figure 14] 10 shows a configuration that adds a twist to the catheter to facilitate passage through a lesion or obstruction. [Figure 15] 10 shows a configuration that adds a twist to the catheter to facilitate passage through a lesion or obstruction. [Figure 16] 10 shows a variation in which the distal end of the catheter has a drilling structure. [Figure 17] 10 shows a variation in which a stent-like support can be deployed from a catheter into a vessel. [Figure 18] 13 shows a variation in which the wire is accessed through a side window in the catheter. [Figure 19] 10 shows a variation in which the wire and catheter carry the markers. [Figure 20] 1 illustrates a concept for focusing shock waves onto a lesion. [Figure 21] 1 shows the enlarged and angled distal end of the catheter. [Figure 22] 1 shows a sleeve with a longitudinal slit to receive and protect the wire during use. [Figure 23] 1 shows a dual lumen catheter with a longitudinal slit. [Figure 24] 1 shows a dual lumen catheter with a longitudinal slit. [Figure 25] 25 shows the catheter of FIG. 24 coupled to a pump for suction. [Figure 26] 1 shows further details of a longitudinal slit catheter. [Figure 27] 13 shows a variation in which the wire is held against the aspiration catheter by a short collar. [Figure 28] 10 illustrates a variation that provides fluid communication between adjacent lumens of a catheter. [Figure 29]13 shows a variation that provides tactile feedback of the relative longitudinal position between the wire and the catheter. [Figure 30] 13 shows a variation in which the catheter has a damping lever for damping excitation of the wire. [Figure 31] 10 illustrates an alternative coupling between the catheter and the actuation unit. [Figure 32] 10 illustrates an alternative coupling between the catheter and the actuation unit. [Figure 33] 1 shows a distal tube extending from the actuation unit around the wire. [Figure 34] 34 shows a distal tube similar to that of FIG. 33 used to manipulate the wire and control its insertion. [Figure 35] 34 shows a distal tube similar to that of FIG. 33 used to manipulate the wire and control its insertion. [Figure 36] 34 shows a distal tube similar to that of FIG. 33 used to manipulate the wire and control its insertion. [Figure 37] 10 shows a further variation of the distal tube. [Figure 38] 10 shows a further variation of the distal tube. [Figure 39] 10 shows a further variation of the distal tube. DETAILED DESCRIPTION OF THE INVENTION

[0061] Figure 1 shows the overall configuration of a system according to the present invention and illustrates some of the major components of such a system. This example features a handheld ultrasonic actuation unit 2 through which extends a centrally aligned flexible transmission member in the form of an intravascular waveguide or wire 4.

[0062] The wire 4 can be inserted into the patient's vasculature and transected to move its distal end to the location of the lesion. When the wire 4 encounters a complex lesion that resists crossing, the actuation unit 2 can be coupled to the wire 4 at an appropriate longitudinal position. When activated, the actuation unit 2 transmits ultrasonic vibrations to and along the wire 4, enhancing the wire 4's ability to cross the lesion via ablation and other mechanisms. The wire 4 can thereby function as a crossing wire to pass through an occlusion within a blood vessel and then remain in situ to function as a guidewire or rail for delivering a subsequent therapeutic device to treat the lesion.

[0063] Typically, the wire 4 may be longer than 2 meters, up to 3 meters, for example. For example, accessing a lesion in or through the foot may involve navigating the wire through the vascular system, typically a distance of 1200 mm to 2000 mm, depending on whether an ipsilateral, contralateral, or radial approach is selected. At this point, the wire 4, tapering distally to a thin 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 the subinguinal or peripheral vessels of the foot; for example, it can be used in coronary artery applications where the ability of the wire 4 to navigate and drill through tortuous, small-diameter arteries is also beneficial.

[0064] The diameter of the distal section of wire 4 determines the flexibility of that distal section and its ability 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, e.g., 0.005" to 0.007" diameter, combines adequate flexibility with the ability to excavate occlusive material for a particular Nitinol having a particular thermal transition temperature.

[0065] The actuation unit 2 may include user controls 6 and, optionally, a display. The actuation unit 2 further comprises a distal hand toggle 8 that can be rotated by a user about a central longitudinal axis of the unit 2 and the wire 4. In particular, the actuation unit 2 can be slid over the wire 4 and coupled to the wire 4 at multiple longitudinally spaced positions by applying torque to rotate the toggle 8.

[0066] To effect the coupling, as shown in subsequent figures, toggle 8 acts on a collet in actuation unit 2 that surrounds and is coaxial with wire 4. When toggle 8 is tightened, the collet grips wire 4 and transmits ultrasonic energy from an integrated ultrasonic transducer in actuation unit 2, optionally through an amplifier horn coupled to the transducer. Wire 4 may be coupled directly to the transducer in some embodiments, in which case the horn may be omitted.

[0067] The movement of the toggle 8 is reversible to release the actuation unit 2 from the wire 4. This allows for the exchange of wires 4 of different sizes, configurations or materials for different purposes. There is also the possibility to exchange transducers, horns and / or collets within the actuation unit 2.

[0068] 1, the ultrasonic signal generator 10 is separate from the actuation unit 2 and is connected to the actuation unit 2 by a connector cable 12. An integrated configuration in which the ultrasonic signal generator 10 is incorporated into the housing of the actuation unit 2 is also possible.

[0069] 1 has an ultrasonic signal generator 10 that is externally powered and therefore includes a power cable 14 that connects to an external power source. Other examples may be powered by an internal battery that may be built into the ultrasonic signal generator unit 10 or the actuation unit 2.

[0070] In general, the system components are preferably portable, and more preferably handheld. Components may be wireless, rechargeable, reusable, and recyclable. Any external cables 12, 14 for transmitting power or signals may be coupled through slip rings to allow free rotation of the cables 12, 14 and avoid entanglement with the wires 4.

[0071] When using ultrasonic energy to excite the wire 4, it is desirable to optimize the displacement amplitude at the distal tip portion of the wire to excavate and traverse the lesion. Conversely, it is desirable to minimize the displacement or movement of the proximal end portion of the wire 4, which is outside the patient's body and may have a portion hanging freely proximal to the actuation unit 2. To accomplish this, the distal length of the wire 4 from the distal tip to where the actuation unit 2 is coupled to the wire 4 should be an odd multiple of a quarter wavelength of the ultrasound. This creates a standing wave in the wire with a vibrating antinode at the distal tip, thus maximizing the amplitude of vibration at the distal tip.

[0072] Referring now also to Figure 2, the wire 4 includes a region whose geometry tapers to provide a change in diameter. Specifically, the wire 4 shown in Figure 2 comprises a substantially straight proximal section 16 and a substantially straight distal tip section 18 that provides a digging portion for traversing the lesion. The distal section 18 is narrower than the proximal section 16 and may be tapered or may have a uniform diameter along its length.

[0073] Distal section 18 is joined to proximal section 16 by a distally tapering transition section 20. Proximal section 16, distal section 18, and transition section 20 are coaxially aligned with one another along the central longitudinal axis of wire 4, but are substantially flexible to bend along their lengths.

[0074] The purpose of the tapered transition 20 is to provide gain and sustain the transmission of ultrasonic energy through the wire 4. For purposes of amplification, the change in cross-sectional area represents a level of gain in both lateral and longitudinal displacement amplitude in the wire 4. The length and diameter of the distal section 18 determine the mode and magnitude of displacement in the axial and radial directions. The transition 20 also affects how the lateral mode of displacement can be established in the distal section 18 of the wire.

[0075] When the distal section of the wire 4 emerges from the surrounding sheath or catheter 22, as shown in FIG. 3, additional low-frequency lateral vibrations may occur. The freedom of motion allows a lateral component to be expressed, and some of the motion may result from a cantilever effect. In this regard, FIG. 3 illustrates how sleeving the wire 4 in this manner allows the desired distal length to be free to vibrate laterally as shown. The distal extent of the sleeving, and therefore the length of the free end of the wire 4, controls the excavation by the distal section 18 of the wire 4. Sleeving or covering the wire 4 at the resonant or harmonic wavelength, so that the distal end of the catheter 22 is substantially aligned with the resonant or harmonic wavelength, allows the wire 4 to excavate a larger aperture.

[0076] If desired, the catheter 22 and / or wire 4 can be moved longitudinally relative to one another in the distal and proximal directions as shown, for example, by rotating a thumbwheel on the actuation unit 2 that acts on the outer sleeve of the catheter 22 as shown in subsequent figures. As will also be described, the behavior of the wire 4 can also be influenced by adjusting the radial gap between the catheter 22 and the wire 4, or by applying a radially inward force from the catheter 22 around the wire 4 as also shown in Figure 3. Compression or forced radial restraint of the wire using a collar, such as a balloon, has variable effects depending on the frequency at hand and the relative position of the acoustic source and where it is coupled to the wire.

[0077] As with all intravascular wires, a balance is required between flexibility, described as "trackability," and stiffness, described as "pushability" or "steerability." Pushability requires longitudinal cylindrical stiffness, while steerability requires torsional stiffness. However, unlike passive wires, the wire 4 must also be capable of transmitting ultrasonic energy to the distal section 18 to assist in traversing the lesion. In this way, the wire 4 functions as a drilling tool along part of its length, not just its tip. In particular, the distal section 18 acts radially as a lateral drilling device to drill an aperture 24 at a lesion 26 within a blood vessel 28, as shown in Figure 4. The wire 4 may also have a distal shaped length to amplify radial drilling.

[0078] Because the goal of the activated wire 4 is to drill through the lesion 26, its dimensions are optimized with the goal of drilling the largest aperture 24 possible for a given power input. In this regard, Figure 4 illustrates how the distal section 18 of the wire 4 can drill an aperture 24 in the lesion 26 whose diameter is larger than that of the wire 4, thus creating a larger lumen through which treatment can be introduced into the lesion 26.

[0079] Specifically, when activated with ultrasonic energy, the distal section 18 of the wire 4 moves in and out and also moves radially in a primary longitudinal mode, mapping and excavating a larger volume at the distal end via lateral movement or radial displacement along the wire 4. The distal section 18 of the wire 4 is also seen to move through lateral and undulating motions at or near the driving frequency under secondary modes of resonant waves and differential harmonics, depending on the operating frequency, the length of the distal section 18, and the torsion of the anatomy. These waveforms can interfere with each other and be more or less effective at excavating material at different moments.

[0080] Thus, when activated, the wire 4 functions as an excavation tool, excavating material distal to the tip 18 of the wire 4 by longitudinal movement of the wire 4 and then tunneling its path by offset translational or lateral movement of the wire 4 within the vessel, providing a lateral offset that opens up the diameter of the tunnel. Thus, the wire 4 abrades the inner surface of the occlusion not only at its distal tip 18 but also along the portion of its length extending proximally from the distal tip 18, creating a wider aperture for passage of a subsequent treatment device over the wire 4.

[0081] The diameters of the various portions 16, 18, 20 of the wire 4 are selected for an optimal balance between pushability and trackability, while allowing standard-sized subsequent devices to use the wire 4 as a guidewire. By way of example, the proximal section 16 may have a diameter of 0.43 mm, and the distal section 18 may have a diameter of 0.18 mm or 0.25 mm. The taper of the intermediate transition portion 20 is slight and therefore greatly exaggerated in these drawings. The transition portion 20 may extend over a length that is a multiple of λ or a fraction of λ, preferably a fraction with a numerator of 1 and an even denominator (e.g., 1 / 2, 1 / 4, 1 / 8, etc.), while the distal section 18 may be λ / 2 or a multiple of λ / 2 or a fraction of λ / 2, such as λ / 4, in length. The optimum lengths we have found for the materials under consideration for sections 18 and 20 are λ, λ / 2, and potentially λ / 4 at lower subharmonics and for thin wires.

[0082] The overall geometry of the wire 4, including its nominal diameter and length, as well as the drive frequency of the system, are determined by the characteristic speed of sound in the wire's material. This characteristic is a function of the material's properties and its geometry. The selected frequency generates harmonics along the length of the wire, and the load at the tip of the wire 4 helps establish a standing wave. The system can generate lateral and longitudinal displacements over a range of frequencies distant from the drive frequency, often occurring at subharmonics of the frequency in the distal section 18.

[0083] In one example, without excluding other dimensions, a wire 4 having a 0.43 mm core cross-sectional diameter defining a proximal section 16 has a tapered transition section 20 optimally positioned to transition to a 0.18 mm diameter distal section 18. The length of each portion 16, 18, 20 of the wire 4 can be selected to have a longitudinal resonant mode at or near the drive frequency, e.g., 40 kHz, with strong subharmonics at or near 20 kHz, 10 kHz, etc. With proper design, there can be adjacent transverse modes near 40 kHz and 20 kHz, etc. There can be an amplification of approximately 2.4 times or other suitable value across the taper.

[0084] As a result, even when the wire 4 is driven with longitudinal vibrations, through appropriate selection of materials, geometry, and distal design features, the desired transverse modes are excited, as shown in Figures 2 and 4. Together, the longitudinal and transverse vibrations contribute to drilling the lesion 26, such that the wire 4 opens an aperture 24 or lumen within the lesion 26 whose inner diameter is substantially larger than the diameter of the wire 4.

[0085] Figures 5, 6, and 7 illustrate how the ability to change the relative longitudinal positions of wire 4 and catheter 22 can be utilized to affect lateral movement of the distal end of wire 4, thereby affecting secondary or lateral excavation, drilling, or tunneling of lesion 26 by wire 4 within lesion 26. In particular, Figures 5, 6, and 7 schematically illustrate how the distal end of wire 4 first penetrates lesion 26 to form longitudinal aperture 24, as shown in Figure 5, and then, with optimized lateral oscillation of wire 4, widens aperture 24 to form a lumen of a desired diameter, as shown in Figures 6 and 7.

[0086] When a sufficient free end length of wire 4 extends distally beyond lesion 26, for example, a length greater than about λ / 4, which in some instances is about 20 mm to 30 mm, lateral vibration at the free end portion begins to laterally excavate the distal segment of lesion 26, as shown in Figure 6. At this stage, a longitudinal spacing or clearance of, for example, about 2 mm, can be maintained between catheter 22 and lesion 26, as shown.

[0087] Next, as shown in FIG. 7 , the activated wire 4 is pulled back proximally through the lesion 26, aided by optimized lateral vibration in the portion of the wire 4 between the catheter 22 and the lesion 26, thereby extending and widening the aperture 24. At this point, extending the longitudinal spacing between the catheter 22 and the lesion 26 to about λ / 4 (by way of example, again about 20 mm to 30 mm) maximizes lateral vibration of the wire 4 in the proximal segment of the lesion 26. The free end of the wire 4 can extend distally, again by way of example, about 2 mm beyond the lesion 26. If necessary, the activated wire 4 can then be pushed back distally through the lesion 26 to further widen the aperture 24.

[0088] Reference is now made to Figure 8, which shows an ultrasonic actuation unit 2 having a longitudinally extending wire 4. In this example, the actuation unit 2 is externally powered and optionally supplied with an ultrasonic signal via a cable 12.

[0089] 8 shows that the actuation unit 2 includes an ultrasonic transducer 30 and a distally tapering acoustic horn 32 attached to the distal face of the transducer 30. A collet 34 couples the wire 4 to the distal end of the horn 32.

[0090] The transducer 30, horn 32, and collet 34 are penetrated by a central lumen to allow passage of the wire 4, whereby the wire 4 extends through the entire length of the actuation unit 2 and emerges proximally from the actuation unit 2. In other configurations, the wire 4 can instead exit laterally from the actuation unit 2 at a location proximal to the collet 34.

[0091] It should be noted that the actuating unit 2 differs from prior art techniques that use an electric motor and cam or spindle to drive the vibration of the wire to convert rotary motion into linear motion. Instead, the actuating unit 2 uses an ultrasonic transducer 30 that utilizes the piezoelectric effect of a piezoelectric ceramic stack, where electrical energy is converted into high-frequency axial linear vibrations. Also unlike prior art techniques, the present invention allows the actuating unit 2 to move along the wire 4 and then be coupled to transmit ultrasonic energy to the wire 4 at any of multiple longitudinally spaced locations along the wire 4. The active wire 4 performs both longitudinal, axial, or directional drilling, as well as radial, lateral, or orbital drilling, via the circumferential movement of the wire 4 from the axial plane of the wire 4 at different harmonics in a consistent and monotonic manner.

[0092] In FIG. 8, the catheter 22, which surrounds and supports the wire 4, can be bonded to the distal region of the wire 4. The bond can be achieved via a mechanical bond, but in this example, it is achieved by a distal annular balloon 36 within the catheter 22, which expands into the distal lumen of the catheter 22, narrowing the lumen of the catheter 22 and providing concentric support around the wire 4. This stabilizes the wire 4 near the center of the lumen of the blood vessel 28 blocked by the lesion 26. If the balloon 36 is designed to abut the wire 4, the surface of the balloon 36 must be able to withstand the fretting effects of the ultrasound-active wire 4, for example, by a compression ring or other means that protects the expanded material from wearing to the point of rupture.

[0093] The balloon 36 may be inflated with a liquid or gas through an inflation port 38 on the catheter 22, which communicates with the balloon 36 through a channel in the wall of the catheter 22. Additional ports and lumens may be included in the catheter 22, for example, to provide aspiration of emboli or debris or particles generated during drilling.

[0094] The balloon 36 may be a compliant or non-compliant material, and the properties and contact length of the balloon 36 may be tailored to optimize drilling and tunneling performance, providing sufficient support to the wires 4 while minimizing negative damping effects on the wires 4.

[0095] Optionally, the balloon 36 or other coupling may be configured to grip the wire 4, applying an inward clamping force to the distal portion of the wire 4. In this scenario, ultrasonic energy is coupled through the waveguide element of the catheter 22, and electromechanical energy can be transmitted from the catheter 22 to the distal tip region of the wire 4 via a connection through the balloon 36. To this end, the balloon 36 may include a metallic element or foil to facilitate the transmission of energy from the catheter 22 to the wire 4, or other such element may be inserted between the balloon 36 and the wire 4. The external metallic element may be in the form of a cutting or abrasive element, or may be in the form of a self-expanding cage that expands with the balloon 36. The atheroma may be fixedly attached to the balloon 36.

[0096] These features can improve cutting or crossing capabilities, particularly lateral cutting, when actuating catheter 22. Actuating catheter 22 can also facilitate passage of the catheter through tortuous anatomy.

[0097] The proximal end of catheter 22 may be coupled to transducer 30 via a mechanical coupling, such as adapter element 40. Subsequent figures expand on other configurations for coupling between catheter 22 and transducer 30 and illustrate possible catheter waveguide element configurations. The proximal end of adapter element 40 abuts the distal end of horn 32 around collet 34 and is thereby coupled to transducer 30 to receive ultrasonic energy.

[0098] In principle, the adapter element 40 can facilitate the transfer of energy from the transducer in any of three modes of operation: the wires 4 are independently activated, the catheter 22 is independently activated, or the catheter 22 and wire 4 are simultaneously activated. In the first mode, the adapter element 40 is disengaged from the horn 32, for example, by being moved distally away from the horn 32. In the second mode, the collet 34 is disengaged from either the horn 32 or the wire 4, either by being moved distally away from the horn 32 or by being moved radially away from the wire 4.

[0099] The adapter element 40 between the transducer 30 and the catheter 22 can be adjusted to optimize and support the length of the wire 4 that would otherwise remain unsupported between the collet 34 and the proximal entrance to the catheter 22. For example, the adapter element 40 may be an adjustable length unit that allows the operator to modify the relative position of the wire 4 and the catheter 22 within a defined range of motion. In one example, the adapter element 40 may be a telescoping coupling that provides lateral support to the wire 4 over a wider range of motion. This reduces the risk of breakage of the wire 4 or other adverse effects of excessive vibration of the wire 4 outside the catheter 22 (such as standing wave formation or damage to the catheter 22).

[0100] Figures 9, 10, and 11 show how a balloon 42 external to the catheter 22 can be used for a variety of beneficial purposes. Such an external balloon 42 can be used separately or in addition to the internal balloon 36 as shown in Figure 8. For example, in Figures 9 and 10, an external distal annular balloon 42 surrounds the distal end portion of the catheter 22.

[0101] 9 shows the catheter 22 after it has been advanced along the blood vessel 28 near the lesion 26. The balloon 42 is then inflated, for example, via an inflation channel in the wall of the catheter 22. This causes the inflated balloon 42 to abut against the surrounding wall of the blood vessel 28, centering the catheter 22, and thus the wire 4 concentrically disposed therein, relative to the lumen of the blood vessel 28. When inflated and engaged with the blood vessel 28 in this manner, the balloon 42 also provides support or damping to the wire 4 through the catheter 22 as the wire 4 advances relative to the catheter 22 and traverses the lesion 26.

[0102] 10 illustrates an optional next step after the wire 4 has traversed the lesion 26 and drilled an aperture 24 in the lesion 26 that is wider than the wire 4. The balloon 42 is then deflated into the lesion 26 and then re-inflated within the lesion 26 in the manner of an angioplasty. The wire 4 can then be actuated again to transmit ultrasonic energy from the wire 4 through the balloon 42 and into the surrounding lesion 26. The balloon 42 thereby functions to clear a wider cross-sectional area of ​​the lesion 26. However, this is optional, as simply inflating the balloon 42 can serve to widen the aperture 24 within the lesion 26.

[0103] The balloon 42 can be deflated, moved, and re-inflated two or more times, each time optionally coupled with an activated wire to remove more of the lesion 26 before follow-up treatment is administered.

[0104] When used to transmit ultrasonic energy from the wire 4 to the surrounding lesion 26, the balloon 42 can contain a fluid, such as a liquid, that acts as a medium when transmitting ultrasonic energy from the wire 4 through the balloon to the lesion. This can act like an ultrasonic bath, improving the effectiveness of the energy transmission. Again, as mentioned above, the balloon 42 may require protective materials to withstand abrasion from the activated wire 4 or for protective layers or elements to be inserted between the balloon 42 and the wire 4.

[0105] The transmission of mechanical vibrations through the balloon 42 can have a beneficial effect on its ability to expand and displace plaque in angioplasty.

[0106] In Figure 11, the external balloon 42 is offset to one side of the catheter 22. As the catheter 22, including the wire 4, is advanced along the blood vessel 28 toward the lesion 26, at least a portion of the balloon 42 expands, compressing the surrounding blood vessel 28. The resulting asymmetric force deflects the catheter 22 laterally away from the longitudinal centerline of the blood vessel 28, thus directing the wire 4 to one side of the centerline. The balloon 42 thereby helps align the wire 4 with the laterally offset lesion 26 depending on where the lesion 26 accumulates.

[0107] Again, balloon 42 , upon inflation and engagement with blood vessel 28 , provides support or damping to wire 4 through catheter 22 as wire 4 advances relative to catheter 22 and crosses lesion 26 .

[0108] It will be apparent that once deflected away from the centerline of the vessel 28, the wire 4 can be steered by rotating the catheter 22 about its central longitudinal axis. In this manner, the wire 4 can be more precisely aimed at laterally offset lesions 26. The wire 4 can also be moved at an angle relative to a large lesion 26 to excavate more of the lesion 26 than would be possible by remaining aligned with the centerline.

[0109] A balloon is not the only way to center and support the wire 4 within the catheter 22. For example, in the configuration shown in Figure 12, and more specifically in Detail A of Figure 12, the catheter 22 comprises multiple layers or tubular components concentrically arranged around the wire 4. These components include an outer sheath 44, a radially compressible body 46 of foam or mesh within the outer sheath 44, an optional insulating layer 48 within the body 46 to insulate the body 46 from the active wire 4, and an inner sheath 50.

[0110] Body 46 may be formed, for example, from a shape memory alloy mesh that has been treated to exhibit enhanced elastic properties with an inflection point in its stress-strain curve under load.

[0111] The inner sheath 50 can be retracted proximally and advanced distally via a user-activated mechanism such as a thumbwheel 52, which may be located, for example, on the housing of the actuation unit 2 or on the proximal hub of the catheter 22, as shown.

[0112] 12, detail B, the walls of body 46 expand such that the inner diameter of body 46 is smaller than the outer diameter of inner sheath 50. Thus, when inner sheath 50 is longitudinally aligned with body 46, body 46 is deformed radially outward by inner sheath 50.

[0113] Specifically, as inner sheath 50 advances distally, it compresses the wall of body 46 against the inside of outer sheath 44. In other words, the inner surface of body 46 is forced radially outward. Conversely, when inner sheath 50 is retracted proximally by rotating thumbwheel 52, body 46 is again free to expand radially inward, returning toward its rest state. In this manner, the expander 46 narrows the lumen of the catheter 22 to provide support around the wire 4, allowing the wire 4 to be pushed down.

[0114] Advantageously, the porosity of body 46 defined by its foam or mesh configuration may help to trap particles generated by the ultrasonic disruption of calcified material in lesion 26 .

[0115] 13 of the drawings, this shows a catheter 22 with a stepped, distally tapering inner lumen profile that internally complements a similarly contoured wire 4. The interlock between opposing stop structures or shoulders 54 of these profiles prevents further distal movement of the wire 4 beyond a certain point, thus ensuring that only a predetermined length of the wire 4 can extend distally beyond the catheter 22. The complementary profiles also help to center the wire 4 within the catheter 22.

[0116] As catheter 22 is pushed through the lumen of blood vessel 28 toward lesion 26 and encounters lesion 26 or a particularly tortuous path, the external pressure on catheter 22 can cause high stiction or blockage, which can further increase the difficulty of advancing catheter 22. Figures 14 and 15 illustrate an embodiment of the present invention that addresses this problem.

[0117] In this embodiment, the catheter 22 has a distally tapered end and includes two tubular coils of bundled filament, i.e., an inner coil 56 within an outer coil 58, in a nested relationship, as seen in Detail A of FIG. 14 . The outer coil 58 is fixed inside the catheter 22. The filaments of each coil 56, 58 follow a partial helical path such that each coil 56, 58 is twisted about the central longitudinal axis of the catheter 22. The coils 56, 58 are twisted in opposite directions such that radially inward movement of the outer coil 58 or proximal movement of the inner coil 56, driven by radially inward compression of the catheter 22, causes the outer coil 58 to rotate about the central longitudinal axis of the catheter 22.

[0118] Thus, when the distal end of catheter 22 encounters a barrier, such as a lesion 26, that requires an increased distal force to be applied to catheter 22, this axial force acting on the tapered distal end causes coils 56, 58 to push together and interact, as shown in detail B of FIG. 14. The interaction between coils 56, 58 generates a torsional force that rotates the distal end of catheter 22, thus creating kinetic friction instead of static friction to facilitate further distal movement of catheter 22. For example, catheter 22 can more easily enter lesion 26 by rotation about its longitudinal axis when trailing behind wire 4 that has already passed through lesion 26, as shown in FIG. 15.

[0119] The tapered distal tip of catheter 22 may include one or more metallic elements to increase the conduction of ultrasonic energy and therefore increase the excavation of lesion 26 when wire 4 is activated and coupled with those elements. The tapered distal tip of catheter 22 may also include serrated edges or burrs to improve its cutting performance upon encountering lesion 26.

[0120] In this regard, Figure 16 illustrates a catheter 22 having a tapered distal tip that includes serrations, burrs, or striations 60 to enhance its tunneling capabilities when encountering a lesion 26, shown here blocking a blood vessel 28. The catheter 22 provides support to the wire 4 as it advances into the lesion 26 under ultrasonic actuation, specifically providing columnar stiffness for pushability and torsional support for steerability in addition to providing centering support for the wire 4 within the blood vessel 28. Synergistically, this interaction and support can improve the lesion crossing capabilities of both the wire 4 and the catheter 22. Supporting the wire 4 and avoiding sharp points or surfaces avoids lacerations and promotes abrasion of the lesion 26 .

[0121] 17 shows two variations of another aid that may be used to center the catheter 22, and thus the wire 4, within the vasculature: open-cell cages 62, 64 at the distal end of the catheter 22. The cages 62, 64 are mesh or web structures that taper longitudinally around the wire 4 at the distal end of the catheter 22, either distally as shown for cage 62 in Detail A of FIG. 17, or proximally as shown for cage 64 in Detail B of FIG. 17. The cages 62, 64 may be tapered to be smaller than the inner diameter of the catheter 22 in order to center the wire 4 relative to the catheter 22.

[0122] Independent of centering the wire 4, the porous or perforated structure of the cages 62, 64 may aid in capturing particles of calcified material produced by ultrasonic disruption of the lesion 26. The cages 62, 64 may also aid in retrieving mass material after traversing or penetrating the lesion 26.

[0123] Either or both of the cages 62, 64 are supported on an inner sleeve 50 within the catheter 22. The outer sheath 44 of the catheter 22 can be retracted relative to the inner sleeve 50, for example, using a thumbwheel 52 on the actuation unit 2, so that the or each cage 62, 64 can be deployed within the blood vessel 28 as a self-expanding stent.

[0124] Only one of the cages 62, 64 may be loaded within the catheter 22, or both may be loaded within the catheter 22. If both cages 62, 64 are loaded within the catheter 22, the distally tapering cage 62 may be released first and the proximally tapering cage 64 may be released next with further retraction of the outer sheath 44. For example, as shown in Detail C, the distally tapering cage 62 may be positioned distal to the lesion 26, and the proximally tapering cage 64 may be positioned proximal to the lesion 26 to capture calcific or mass material.

[0125] The catheter 22 can be used to aspirate larger amounts of material into the catheter 22 when the cages 62, 64 are expanded, especially in the case of the proximally tapering cage 64 shown in Detail B of Figure 17. When the cages 62, 64 are closed by the cover, it can also stop or slow blood flow to an occlusion such as a lesion 26.

[0126] Optionally, each cage 62, 64 may have anchoring points or formations, for example at its wider end, for adhering to fibrous portions of the mass or to vessels, but without risk of vascular intrusion.

[0127] 18 illustrates another adaptation of the catheter 22, in this example showing an opening 66, such as a window or slot, in the side near the distal end of the catheter 22. The lateral opening 66 exposes the active wire 4 transversely or laterally to the wall of the lesion 26 or vessel 28. This allows the wire 4 to be displaced laterally to target the wall of the lesion 26 or vessel 28, enabling lateral, transverse, or directional atherectomy or debulking. The wire 4 can loop out of the opening 66 to make stronger contact with the vessel wall.

[0128] In this example, as best seen in Detail A of Figure 18, the portion of wire 4 aligned with opening 66 has an undulating profile that defines lateral protrusions that can protrude through opening 66 or better engage lesions 26 located adjacent the fenestration. Detail B of Figure 18 also shows how wire 4 within catheter 22 is exposed by aperture or opening 66.

[0129] 19 is a schematic diagram showing radiopaque markers 68 at the distal ends of both the wire 4 and the catheter 22. When aligned in a particular way, these markers 68 indicate to the operator where to clamp the wire 4 for maximum resonance. This avoids the need for markers at the proximal end of the device, but may require the collet 34 of the actuator unit 2 to be locked a fixed distance from the proximal end of the catheter 22.

[0130] The longitudinal vibration of the wire 4 at the distal end of the catheter 22 generates pressure waves within the fluid, i.e., blood, filling the blood vessel 28. At ultrasonic frequencies, these pressure waves can cause cavitation, which has the potential to advantageously erode solid material, such as that of a lesion 26, such as a chronic total occlusion or CTO. However, the pressure waves propagate in all directions, with random reflections from surrounding surfaces, particularly the cap at one end of the CTO lesion 26 and the cylindrical wall of the blood vessel 28. In the event that an enhanced standing wave pattern does not exist, the energy of the cavitation is dissipated.

[0131] 20, which shows a deformable, radially expanded distal surface 70 of catheter 22. When distal surface 70 of catheter 22 forms a paraboloid, and the diameter of surface 70 is large enough to substantially fill the cross-section of blood vessel 28, pressure waves 72 in the fluid within blood vessel 28 are directed to the focus of the parabola. In this manner, the energy of waves 72 may be focused onto lesion 26, and cavitation erodes the calcified material of the CTO. Such erosion due to cavitation increases the erosion due to mechanical action of the activated wire 4 .

[0132] Detail A is a cross-sectional view showing the parabolic shape of distal surface 70 of catheter 22. As the concave curvature of that surface increases, the focal length of the parabola decreases.

[0133] 21 shows another catheter 22 having an enlarged distal end or mouth 74 that lies substantially in a plane that is at an acute angle to the longitudinal axis of the wire 4. This wider mouth 74 at the end of the catheter 22 better accommodates material or debris during aspiration. Radiopaque material or markers can be affixed to the beveled surface to allow visualization of the location or orientation of the mouth 74 at the distal end.

[0134] Beneficially, the acutely angled plane of the port 74 creates a more tapered or sharply pointed distal profile for the catheter 22, resulting in a lower crossing profile and easier penetration. In this case, the angled port 74 also provides one-sided coverage of the active wire 4 to prevent damage to the sidewall of the vessel 28 when forward drilling or drilling only the cap of the CTO lesion 26 is required. This is intended to keep the wire 4 within the true lumen or as the wire travels between the wall of the vessel 28 and the lesion 26.

[0135] Turning now to FIG. 22 , this shows a flexible, tubular, protective catheter or sheath 76. At the beginning of a procedure, the sheath 76 extends along and around the distal portion of the wire 4 that extends between the working unit 2 and a luer or introducer that defines an entry port 78 into the patient's body. The purpose of the sheath 76 is to enclose and protect this length of wire 4, which would otherwise be exposed before being advanced into the patient's body. The wire 4 can easily pass through the loose sheath 76, which prevents the wire 4 from coming into contact with any material that could contaminate the wire 4. The catheter or sheath can assist in restraining lateral components along the length of the catheter or sheath, as well as allowing the wire to be immersed in a liquid medium along its length.

[0136] The sheath 76 is particularly useful when a long length of wire 4 must be inserted into a patient, such as when crossing a blockage in the distal tibial or foot arteries. In particular, by providing support or preventing kinking, the sheath 76 helps such substantial lengths of wire 4 be inserted in a single continuous movement, rather than intermittently in a series of shorter movements, as would be the case if the actuation unit 2 were instead repeatedly clamped to and released from the wire 4. The sheath 76 may be sized, at least in part, so that the distal end can be inserted within a support catheter over a portion of its length, e.g., 20 cm.

[0137] Thus, instead of being held near the introducer 78, the actuation unit 2 is coupled to the wire 4 at a location away from the entry port 78, so that the entire length of the wire 4 is ready to be introduced into the target vessel. As a result, a user can simply clamp the actuation unit 2 to the wire 4 at a proximal location, more than a meter away from the patient's body, and then, with a single, uninterrupted motion, actuate and deliver a long portion of the wire 4 into the body. This is useful when actuation of the wire 4 may be required to facilitate delivery or tracking of the wire 4.

[0138] The sheath 76 must not impede the distal movement of the actuating unit 2 and wire 4 toward the entry port 78. Thus, the sheath 76 may collapse or accord along its length as the actuating unit 2 and wire 4 are advanced distally. In another approach, as shown here, the sheath 76 has a longitudinal closure or aperture, such as a groove or slit 80, along its length, which is split longitudinally and then peeled away from the wire 4. This provides clearance for the actuating unit 2 and wire 4 as they advance distally together through the sheath 76.

[0139] The principles of longitudinal closure shown in the sheath 76 of Figure 22 can also be applied to catheters, as described with reference to Figures 23-27. These embodiments also disclose a multi-lumen catheter 22 with at least two parallel lumens. Specifically, these embodiments disclose a dual-lumen configuration with a guidewire lumen 82 for receiving and accommodating the ultrasonic actuation wire 4 and a second lumen 84 for receiving additional or alternative devices or for carrying fluids, for example, for aspirating embolic material removed from a lesion during a procedure. Thus, the catheter 22 becomes a dual-purpose aspiration and actuation catheter.

[0140] Guidewire lumen 82 provides containment for wire 4, stabilization and restraint of lateral displacement of wire 4, and uniform damping of wire 4 when wire 4 is activated.

[0141] The longitudinal closure provides for entry and exit of the wire 4 into and out of the guidewire lumen 82 at almost any location along the length of the catheter 22, not just at the proximal end. Thus, the wire 4 can enter and exit the guidewire lumen 82 at either the distal or proximal entry point. In particular, the guidewire lumen 82 has a closure, such as a slit 80, extending from its proximal end to a distance of approximately 150 mm to 300 mm from its distal end. This facilitates entry and exit of the wire 4 into and out of the guidewire lumen 82 as the wire 4 travels through the vessel and the user wishes to accommodate the wire 4 for practical purposes, such as fluid excitation or attenuation. Thus, this feature allows the wire 4 to break laterally through the catheter 22 as the catheter 22 is advanced through the vessel and / or any lesion when the wire 4 is ultrasonically actuated.

[0142] As best seen in Detail A of Figure 26, the proximal portion of guidewire lumen 82 may be defined by a channel section comprising opposing webs separated by slits 80. The resilience of the channel sections pushes the webs together around slits 80 to surround and accommodate wire 4. The webs may then abut or overlap one another, as shown on the left and right sides, respectively, of Detail B of Figure 26. Figure 26 also shows that a second lumen 84 may terminate proximally beyond guidewire lumen 82.

[0143] When slit 80 terminates short of the distal end of catheter 22, the wall of guidewire lumen 82 remains intact and is circumferentially continuous at its distal portion 86. The integrity of distal portion 86 allows wire 4 to guide catheter 22 along a desired path through the vasculature. The short length of distal portion 86 relative to the overall length of catheter 22 and wire 4 makes it easy and quick for a single operator to load and unload catheter 22 onto wire 4 during a procedure.

[0144] The distal end of guidewire lumen 82 may be flush with the end of catheter 22 or may be proximally offset from the distal tip of catheter 22. Conversely, second lumen 84 is shaped at its distal tip to create an opening with a large area to facilitate capture and aspiration of soft plaque or other embolic material. For example, the opening may lie in a plane that intersects second lumen 84 at an acute angle relative to the central longitudinal axis of catheter 22.

[0145] In another embodiment, the diameter of the second lumen 84 may be larger in the proximal section than in the distal section. The distal taper of the second lumen 84 may allow for more efficient wicking of bulk particles or vulnerable plaque.

[0146] Aspiration is achieved through a negative pressure suction pump 88, shown in Figure 25, such as a syringe under vacuum, coupled to a proximal port in communication with the second lumen 84. At appropriate points in the procedure, the aspiration pump 88 can be activated to aspirate and remove debris generated during passage through the lesion.

[0147] As noted above, FIG. 26 illustrates that second lumen 84 may terminate proximally beyond guidewire lumen 82. This possibility is taken to an extreme in the variation shown in FIG. 27, in which guidewire lumen 82 is shortened to a collar attached to the distal end region of second lumen 84 and extending proximally a short distance from the distal tip of catheter 22. Wire 4 is merely secured to catheter 22 by shortened guidewire lumen 82 and is free to extend away from second lumen 84 proximally of guidewire lumen 82. Functionally, guidewire lumen 82 is similar to the short distal portion 86 beyond the distal end of slit 80 in FIG. 23.

[0148] The provision of at least two lumens in the shaft of catheter 22 can be utilized for other purposes. For example, FIG. 28 shows a second lumen 84 used as an infusion lumen and a vent hole 90 penetrating the wall between second lumen 84 and guidewire lumen 82. Vent hole 90 serves as a cross-channel for infusion of fluid from second lumen 84 into guidewire lumen 82, thereby lubricating movement of actuation wire 4 within guidewire lumen 82.

[0149] The fluid injected may be in the form of water or saline, or a cooling fluid, or a medication, perhaps to promote dissolution.

[0150] The second lumen 84 carrying the fluid may be closed at the distal tip so that the fluid is delivered at high pressure through the vent 90. This may create pressure at the distal end of the wire 4 or may push down on the distal section, affecting lateral movement of the wire for some benefit. Distal lateral attenuation can be provided through the delivered fluid, which can have a high or low viscosity, or can be a contrast fluid.

[0151] Returning to the proximal end of the catheter 22, Figure 29 shows a variation of the catheter 22 that includes an internal detent protrusion 92 that faces radially inward toward the wire 4. Correspondingly, the wire 4 has a complementary protrusion 92 that faces radially outward toward the catheter 22. Such a protrusion 92 on the wire 4 may be defined, for example, by a band around the wire 4 .

[0152] During the relative telescopic movement between the catheter 22 and the wire 4, the opposing sets of protrusions 92 ride up against each other with a resilient click or snap action, which provides audible and tactile feedback to the user regarding the relative longitudinal positions of the catheter 22 and the wire 4 during that telescopic movement.

[0153] 29 also includes an integral bulbous enlargement 94 near its proximal or hub end. The enlargement 94 provides a convenient rest or stop for a user's finger to avoid inadvertently touching an activated wire 4 that may be exposed beyond the proximal end of the catheter 22. In this regard, it should be noted that the protrusion 92 within the catheter 22 is positioned distally near the enlargement 94 and thus aligned with the user's finger for enhanced tactile feedback.

[0154] A bulbous proximal enlargement 94 is also a feature of the catheter 22 shown in FIG. 30 . In this case, the catheter 22 includes a damping lever 96 near its distal enlargement 94, thus also being aligned with the user's grip. The damping lever 96 is resiliently hinged to the wall of the catheter 22 and includes a stud 98 on its underside that can be received by an opposing opening 100 in the wall of the catheter 22. When the damping lever 96 is depressed, for example by the user's thumb, this pushes the stud 98 through the opening 100 into contact with the active wire 4, applying a radial damping force to the wire 4. The stud 98 can include a damping material that resists abrasion by the wire 4.

[0155] It will be recalled that some embodiments of Figure 8 illustrate an interface between the actuation unit 2 and the catheter 22. In this regard, Figures 31 and 32 show other configurations for coupling the catheter 22 to the ultrasonic energy generated by the transducer 30 of the actuation unit 2.

[0156] In Figure 31, a threaded collet 34 couples the wire 4 to the transducer 30, and a secondary coupling connects the catheter 22 to the collet 34. The secondary coupling comprises a catheter adapter cap 102 having internal threads that complement the external threads of the collet 34, and a catheter mating ferrule 104 having a through hole that is received by the catheter adapter cap 102 and allows the wire 4 to pass unimpeded through the assembly. The proximal end flange of the mating ferrule 104 can be compressed against the collet 34 by tightening the adapter cap 102 proximally along its threaded engagement with the collet 34.

[0157] The tubular wall of catheter 22 contains an elongated waveguide 106 that extends distally along the length of catheter 22 and may terminate in a distal mass 108. At their proximal ends, where catheter 22 is received in a hub 110 that may be attached to the housing of actuation unit 2, waveguide 106 terminates in a waveguide terminal 112. Waveguide terminal 112 connects waveguide 106 to the distal end of coupling ferrule 104, and thus to transducer 30 via coupling ferrule 104. Transducer 30 is thus coupled to wire 4 and catheter 22 via collet 34 for simultaneous actuation of wire 4 and catheter 22.

[0158] The waveguides 106 may be arranged in a straight longitudinal configuration, as shown in Figure 31. Alternatively, they may be helically twisted about the central longitudinal axis of the catheter 22. The catheter 22 may have one or more waveguides 106. If two or more waveguides 106 are employed, they may extend parallel to one another or may be braided.

[0159] In an alternative configuration shown in FIG. 32 , a catheter adapter cap 102 is attached to the externally threaded distal horn portion of the transducer 30. The adapter cap 102 presses the proximal flange of a catheter coupling ferrule 104 against the distal end of the transducer 30. The coupling ferrule 104 is thus held in direct contact with the transducer mass. To this end, the coupling ferrule 104 surrounds a collet 34 that is separately threadably engaged with the transducer 30. The distal side of the coupling ferrule 104 is coupled to a waveguide 106 extending along the catheter 22. The transducer 30 is thus coupled to the wire 4 via the collet 34 and to the catheter 22 via the coupling ferrule 94, activating the wire 4 and the catheter 22 simultaneously.

[0160] The proximal hub 110 encloses the coupling mechanism and provides a means for attaching an inflation and / or suction device to the catheter 22 via one or more ports 38 on the body of the hub 110 .

[0161] In the configurations of Figures 31 and 32, connections to collet 34 or transducer 30 can be made using connection means other than mating threads, such as a friction taper fit, a luer connector, or a bayonet connector.

[0162] 33, which shows an actuation unit 2 having a rigid, elongated, distally extending tube 114 that forms a tubular nose, sleeve, or sheath around the wire 4. The tube 114 projects distally from the distal end of the actuation unit 2 and surrounds and covers the portion of the wire 4 adjacent the actuation unit 2. The tube 114 provides strain relief for the wire 4.

[0163] In one mode of use, the tube 114 can be connected to a hub at the proximal end of the catheter, which allows the user to secure the hub to the actuation unit 2. In a second mode of use, the tube 114 can fit over the proximal end of the catheter while allowing the hub and catheter to telescope along the tube 114. In that case, the wire 4 can remain covered as the actuation unit 2 and the catheter hub are moved closer to or further apart. In both cases, the tube 114 covers the wire 4 protruding from the actuation unit 2, protecting the user and the wire 4 itself.

[0164] 33 also illustrates the option of a wire 4 having longitudinally spaced markers 116. Such markers 116 can guide the user as to where the actuation unit 2 should be coupled to the wire 4 to optimize the drilling of the lesion at the distal end of the wire 4.

[0165] The tube 114 extending distally from the actuation unit 2 around the wire 4 can be used for a variety of purposes in accordance with the present invention. For example, complementary protrusions, such as those in the catheter of FIG. 29, can provide audible and tactile feedback through a clicking or snapping action during telescopic movement between the tube 114 and the wire 4. Similarly, the tube 114 can have a damping lever, such as that shown on the catheter of FIG. 30, that allows the user to apply a lateral damping force to the wire 4.

[0166] Referring now to Figures 34-36, these figures show a safety feature in which tube 114 is used to prevent actuation unit 2 from advancing too far distally towards the patient during a procedure where there may be a risk of losing wire 4 within the patient's body if wire 4 breaks.

[0167] 35 , tube 114 acts as a spacer that prevents the user from advancing actuation unit 2 all the way to the luer or introducer that defines entry port 78 into the patient's body. The length of tube 114 imposes a standoff distance between actuation unit 2 and entry port 78. The distal end of tube 114 may be bulbous or otherwise enlarged, as shown, to act as an end stop or insertion limiter that prevents tube 114 from entering entry port 78.

[0168] The length of the tube 114 ensures that, even if the wire 4 breaks, a portion of the wire 4 will always remain outside the patient's body. Specifically, if the wire 4 breaks near its attachment point to the transducer 20 in the actuation unit 2, a length of the wire 4 that is at least as long as the tube 114, and typically somewhat longer than the tube 114, will always remain outside the inlet port 78. In this case, friction between the wire 4 and the tube 114 helps prevent the wire 4 from sliding distally along the tube 114 and into the patient's body.

[0169] 36 shows that the tube 114 may have the additional attribute of being radially compressible between the user's fingers so as to grip the wire 4 within the tube 114 in the event of breakage. This helps the user prevent the broken end of the wire 4 from being pulled into the patient's body. The tube 114 may be compressible in this manner at its proximal end or any point along its length, but is preferably compressible at or near its distal end, as shown.

[0170] Advantageously, the tube 114 may also be easily removed from the actuation unit 2 to allow quick access to the wire 4. To this end, the tube 114 is easily removable from the distal end of the actuation unit 2 by releasing a removable connector 118 at the proximal end of the tube 114 from the distal side of the toggle 8. The tube 114 may then be removed from the actuation unit 2 by, for example, a twist-off or press / pull configuration.

[0171] Thus, the user can squeeze the tube 114 to grasp the broken wire 4, and then, while still grasping the wire 4, pull the tube 114 away from the actuation unit 2 to ensure that the wire 4 remains outside the patient's body.

[0172] Finally, referring to Figures 37-39, these figures show an embodiment in which the distal tube 114 is distally extendable and proximally collapsible while remaining attached to the distal end of the actuation unit 2.

[0173] By providing a longitudinal extension, the length of the tube 114 can be adjusted to allow for adjustment of the attenuation over different lengths of the wire 4. It also allows the length of the tube 114 to be adjusted to allow for differences in longitudinal spacing between the actuation unit 2 and other structure disposed distally of the actuation unit 2, such as the proximal end of the catheter 22 as shown in the previous embodiment, or the inlet port 78 as shown in FIG. 35. The tube 114 can thereby function as a connector between the actuation unit 2 and structure disposed distally of the actuation unit 2.

[0174] 37-39 are longitudinally stretchable and compressible, but may be laterally or radially stiff or otherwise less compressible to protect and guide the wire 4 or to apply damping forces to the wire 4. In particular, some lateral stiffness can aid in applying damping forces to the wire 4.

[0175] In Figure 37, tube 114 comprises a series of nested rigid tubular sections 120. Tube 114 is shown in a collapsed and expanded state in Detail A of Figure 37.

[0176] As best shown in Detail B of FIG. 37 , the distal most portion of section 120 has a bulbous tip 122 for the user to grasp as they pull out section 120 to extend tube 114. A bump-fit ​​feature 124 on the proximal end of tube 114 allows for easy attachment of tube 114 to actuation unit 2. A colored band 126 in central portion 120 of tube 114 provides a visual cue to allow the user to identify when tube 114 is in an optimal extension state for wire 4 to perform atherectomy of the lesion at the distal tip of wire 4.

[0177] 38 shows a braided tube 114 that can function as a secondary sheath or connection adapter extending around the wire 4 between the actuation unit 2 and the catheter hub. A longitudinal slit 128 extends along the entire length of the tube 114 to allow the wire 4 to be placed laterally within the lumen of the tube 114, if desired. Connection of the rigid end fittings of the tube 114 to the actuation unit 2 and catheter hub can be by snap fit, bump fit, or other convenient means.

[0178] The braided central portion of the tube 114 allows for longitudinal expansion and contraction. In this regard, the tube 114 is shown in a collapsed and expanded state in Detail A of FIG. 38. The tube 114 is thus a variable-length unit that allows the operator to change the relative longitudinal position of the wire 4 and the catheter within a defined range of motion. The extensibility of the tube 114 also provides strain relief or lateral support for the wire 4 over a wider range of motion, reducing the risk of wire 4 breaking or the adverse effects of excessive vibration of the wire 4 outside the catheter.

[0179] Finally, Figure 39 shows a tube 114 with an extendable central portion having a bellows-like, concertina, or accordion configuration. A colored middle portion 130 of the tube 114 appears as the tube 114 is extended and is fully visible when the tube 114 is fully extended, as shown in Detail A of Figure 39. Again, this provides a visual cue so that the user can identify when the tube 114 is at an optimal extension for the wire 4 to perform an atherectomy of the lesion at the distal tip of the wire 4.

[0180] Depending on its properties, such as stiffness, the tube 114 shown in Figures 33-39 can have a variety of functions. For example, the tube 114 can provide strain relief to limit the degree of bending that can be applied to the wire 4 by locally restraining the wire 4 against lateral movement, noting that NiTi is strain-sensitive and strain in the area of ​​the collet will promote fracture. The tube 114 can also provide additional safety by contacting the wire 4, allowing the user to interface with the active wire 4 if desired.

[0181] The tube 114 can also facilitate wire capture, as the wire 4 can be wet, slippery with fluid, and therefore difficult to grasp, especially when activated. The tube 114 can be used to capture a broken wire 4, as described above, but more generally, the tube 114 may be used to capture and hold the wire 4 in place to prevent loss of position, which is important for subsequent treatment, and may also be used as an aid in optimal positioning of the wire 4 for activation. The tube 114 also provides a means for allowing immersion of the wire 4 in a fluid medium, such as a liquid. The longitudinal extensibility of the tube 114 is also useful for maintaining a continuous and controlled distance from ports such as luer locks.

[0182] Many other variations are possible within the concept of the present invention, for example, a multi-lumen catheter could deliver a therapeutic active wire in one lumen in parallel or simultaneously with a passive guidewire in another lumen.

Claims

1. 1. An intravascular device for passing an obstruction in a blood vessel, the intravascular device comprising: an elongated intravascular element, such as a wire, comprising a proximal section, a distal tip section having a smaller diameter than the proximal section, and a distally tapering intermediate section extending between the proximal section and the distal tip section; an ultrasonic transducer mechanically coupled to the proximal section of the elongated intravascular element for ultrasonically actuating the elongated intravascular element, thereby exciting the distal tip section to facilitate passage through the obstacle; an intravascular device comprising: a tube surrounding the elongated intravascular element, the tube extending distally from an actuation unit housing the ultrasound transducer;

2. The intravascular device of claim 1 , wherein at least a portion of the tube has a structure that provides greater lateral stiffness than longitudinal stiffness.

3. The intravascular device of claim 2 , wherein the tube is longitudinally extensible and collapsible.

4. The intravascular device of claim 3 , wherein the tube comprises a series of telescoping rigid tubular sections.

5. The intravascular device of claim 3 , wherein the tube comprises a corrugated or braided structure.

6. The intravascular device of claim 1 , wherein a portion of the tube has a structure that provides greater longitudinal stiffness than lateral stiffness.

7. The intravascular device of claim 6 , wherein a portion of the tube is user-compressible in a radially inward direction into contact with the elongate intravascular element.

8. 8. The intravascular device of claim 6 or 7, further comprising a detachable connector at the proximal end of the tube.

9. 9. The intravascular device of claim 8, wherein the connector is operable to detach the tube from the actuation unit by applying a twist-off or press / pull action to the tube.

10. The intravascular device of any one of claims 1 to 9, wherein the tube is connected to a hub at the proximal end of a catheter.

11. 11. The intravascular device of claim 10, wherein the tube fits over the proximal end of the catheter while the hub and catheter are telescopically movable along the tube, thereby allowing the elongated intravascular element to remain covered even as the actuation unit and the catheter hub are moved closer together or further apart.

12. The intravascular device of any one of claims 1 to 11, wherein the distal end of the tube is bulbous or enlarged.

13. 13. The intravascular device of claim 12, wherein in combination with an entry port, such as a luer, the enlarged distal end of the tube is an insertion limiter that prevents the tube from entering the entry port.

14. 14. The intravascular device of any one of claims 1 to 13, wherein the tube includes internal detent projections facing radially inward toward the elongate intravascular element, and the elongate intravascular element has complementary projections facing radially outward toward the tube, such that during relative telescopic movement between the elongate intravascular element and the tube, opposing sets of projections ride over each other with a resilient click or snap action.

15. 15. The intravascular device of any one of claims 1 to 14, wherein the tube comprises a damping lever resiliently hinged to the wall of the tube, the stud being provided on an underside of the tube that can be received in an opening on the opposite side of the wall of the tube when the damping lever is depressed to force a stud through an opening and into contact with the elongate intravascular element.

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