Guidewire for intravascular device

Abstract

An elongated intravascular element for passing through an obstruction in a blood vessel includes: a proximal segment; a distal tip segment with a diameter smaller than that of the proximal segment; and a distally tapering intermediate segment extending between the proximal segment and the distal tip segment; wherein the length of the tapering intermediate segment is substantially λ / 2 or a multiple of λ / 2, where λ is the wavelength of the driving frequency that will produce longitudinal resonance in the element.

Description

Technical Field

[0001] The present invention relates to treating local ischemia by using ultrasound-activated wires or other slender elements to pass through blockages in blood vessels and facilitate the introduction of subsequent treatment devices.

[0002] Previous patent applications

[0003] This invention develops the concepts expressed in the international patent application published as WO 2020 / 094747 and the unpublished GB patent application No. 2006665.0, the contents of which are incorporated herein by reference. Background Technology

[0004] In endovascular surgery, arteries are selected and recruited to obtain access to the vascular system. Selection is based on the artery's ability to adapt to the intended diagnostic or therapeutic device at the target site and its ability to minimize tissue and patient trauma.

[0005] In procedures such as revascularization of peripheral arteries or veins, access is typically established through surgical incisions and punctures in the femoral, popliteal, tibial, and / or foot arteries—a technique commonly known in medical terminology as the Seldinger technique. Once access is granted, a guide wire and guide sheath are inserted into the vessel and secured at the site. This sheath serves as a port for device introduction, withdrawal, and replacement, minimizing abrasion to the arterial tissue. A guiding catheter and guidewire are then introduced into the artery to provide further protection and assist in device navigation and delivery of treatment to the target site.

[0006] The guidewire is carefully advanced along the lumen of the blood vessel to avoid any trauma to the vessel wall and to guide it to the site of obstruction. In a successful procedure, the guidewire is then advanced across or through the obstruction and held in place to act as a guide through which diagnostic or therapeutic devices, such as balloon catheters and stents, are tracked to the site of blockage. Guidewires are used in other minimally invasive procedures to introduce other devices and instruments into other lumens of the blood vessel or body for examination, diagnosis, and different types of treatment.

[0007] Guidewires are used in procedures such as balloon angioplasty, gastrointestinal surgery, urological surgery, and gynecological surgery. All of these procedures require navigating through the blocked passageway to facilitate access to the lesion site or other target tissues distal to the lesion via a larger and often bulkier device.

[0008] Guidewires are crucial for therapeutic interventions and are made from various materials, most typically stainless steel and various alloys, including NiTi (nickel-titanium), cobalt-chromium alloys (CoCr), and many different designs. Their fabrication involves altering the chemical composition and microstructure morphology of the material, for example, by cold-working the material simultaneously into a wire, and then machining the wire into different dimensional designs and applying different heat treatments to achieve the desired performance. As an example, a specific taper can be machined along the length of the wire to create a differential degree of flexibility along its length. Thus, the wire will have sufficient flexibility at its distal end to conform to the shape of the blood vessel and possess the strength to transmit force to the tip (“tip strength”) or the force to penetrate the lesion.

[0009] In conventional guidewires, the tapered section is encased in a coil or sheath material, which allows for flexibility through the tapering while enabling force to be transmitted through the coil to the distal tip of the wire. As will be explained, such a coil or sheath material is not necessary in the wire of the present invention because force is transmitted via ultrasonic energy to excavate the cavity even if the wire is uncoated or unsheathed.

[0010] The length of the lead used in endovascular surgery also varies depending on the distance it is considered possible to traverse. For example, leads typically ranging from 750 mm to 900 mm in length are used in many peripheral applications where they may be introduced into femoral or popliteal anatomy, or where occlusions need to be traced and traversed in the ipsilateral iliofemoral and subpopliteal arteries. Lead lengths used in ipsilateral and coronary applications are often around 1200 mm, 1500 mm, or 1700 mm. In practice, leads that can be traced contralaterally can be longer, ranging from approximately 2000 mm to 2250 mm, 2500 mm, or 3000 mm. The most common lead lengths on the market are 1750 mm, 1950 mm, and 3000 mm.

[0011] In many cases, extension leads can be used to facilitate the deployment of certain therapeutic devices known as over-the-wire (OTW) devices. In this case, the proximal end of the lead may require certain features.

[0012] Many conventional intravascular leads are passive mechanical devices without active components. Passive leads transmit no energy other than that applied by the clinician. They are operated by being pushed, pulled, and twisted proximally to navigate to the site of the blockage and then pushed through or around it. They have different constructions and designs to facilitate access to and passage through lesions in different anatomy and are used with different devices. However, in many cases, the blockage is too challenging to pass through for conventional leads. These passive leads do not work as expected of guidewires, or they are limited when attempting to pass through near-blockage or completely blocked blockages that may also be significantly calcified. In cases where these passive leads are being tracked around the blockage, such as in subintimal situations, such leads are often unsuccessful in re-entering the true lumen.

[0013] This invention relates to the use of ultrasonic vibrations transmitted along a wire to penetrate blockages. US 3433226 discloses the transmission of ultrasonic vibrations along small-diameter conduits and assemblies. US 5971949 describes the transmission of ultrasonic energy through waveguides with different configurations and tip geometries. US 5427118 describes an ultrasonic guidewire system, but does not discuss in detail the proximal geometry of the wire or how it facilitates subsequent devices via the wire-through method.

[0014] Many current single-transducer systems are not ultrasonically activated guidewires, but rather ultrasonically activated catheters containing wire components for agitating and ablating material. US 6855123 and US 4979939 describe such systems. These catheters themselves require separate passive guidewires to aid in their navigation, and therefore, they are tools that facilitate the passage of individual guidewires through blockages. US9629643 illustrates a system with a series of distal tip configurations, but all require separate guidewires for entry.

[0015] These devices are designed to deliver alternative methods of revascularization and are generally described as atherosclerotic devices, crossing devices, or vascular preparation devices. In limited exceptions, these devices are not intended to pass through lesions or serve as device delivery systems. In the art, these ultrasound devices and conduit reconstruction lead devices enhance revascularization and reduce lesion volume by removing the plaque that forms the lesion, thereby providing or enabling atherosclerotic plaque resection.

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

[0017] Ultrasound-activated catheter and lead systems were previously considered a method for percutaneous procedures or atherosclerotic plaque resection and for preparing blood vessels for angioplasty. Some products were commercially available in the past, some remain on the market, and some newer systems have recently become available. These catheter and lead systems typically consist of an ultrasound generator and an ultrasound transducer. The ultrasound generator converts mains power into ultrasonic waves, defined by their voltage amplitude, current, and frequency. The ultrasound transducer, and typically an amplifying horn, converts electrical energy into high-frequency mechanical vibrations, defined by the frequency and amplitude of the vibrations.

[0018] Small-diameter wire waveguides are directly coupled to the transducer at their proximal end, or through any corner, and 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, with the aim of ablating material and ultimately facilitating revascularization or vascular reconstruction of blood vessels and anatomical structures throughout the body. The tissue and material near the distal tip are affected by a combination of the ultrasonic movement of the tip and its direct mechanical abrasion, ablation, and cavitation from the pressure wave component and the acoustic flow that removes ablated material from the area surrounding the tip.

[0019] In known ultrasound-activated intravascular lead systems, the proximal end of the guidewire is connected to the transducer. In patent application WO2020 / 094747, the lead wire passes through the transducer and extends not only distally but also proximally. This allows the user to couple the transducer to the lead wire at any desired location and adjust the total length of the distal portion of the lead wire without cutting it. The ability of the lead wire to travel or extend through the transducer and be coupled to it at multiple locations has very useful practical benefits, stemming from the ability to adjust the total length of the distal portion of the lead wire, for example, to adapt to the desired trajectory length required for the lead wire tip to travel within the patient's body. Similarly, it enhances control over the lead wire to maintain its in-situ placement within the vascular lumen while adjusting or reconnecting the activation source. Additionally, the adjustable length of the distal portion of the lead wire facilitates the achievement and optimization of resonance at any desired frequency at the distal tip.

[0020] In developing the concept disclosed in WO 2020 / 094747, the inventors recognized the need to improve upon pre-existing intravascular guides in various aspects, both for the concept in WO 2020 / 094747 and others. There is a need for intravascular guides that are easier to manufacture, easier to navigate to the lesion site, simpler and more effective to activate and control, and more effective at traversing lesions while forming a larger lumen that better facilitates flow along the vessel and accommodates subsequent treatment.

[0021] The purpose of this invention is to address one or more drawbacks associated with the prior art. Summary of the Invention

[0022] According to one aspect of the invention, an elongated intravascular element is provided for passing through an obstruction in a blood vessel. The element comprises:

[0023] Proximal section;

[0024] The distal tip segment, wherein the diameter of the distal tip segment is smaller than the diameter of the proximal segment; and

[0025] A distally tapering intermediate section extends between the proximal section and the distal tip section.

[0026] The length of the tapered intermediate section is substantially a multiple or even fraction of λ / 2 in the sequence λ / 4, λ / 8..., where λ is the wavelength of the driving frequency that will produce longitudinal resonance in the element.

[0027] The invention also resides in an intravascular device for traversing obstructions in a blood vessel, the device comprising an elongated intravascular element of the invention and an ultrasonic transducer mechanically coupled to the element to ultrasonically excite the distal tip segment of the elongated intravascular element to facilitate traversing the obstruction.

[0028] The present invention also provides a method for ultrasonically exciting a distal tip segment of an elongated waveguide element, the method comprising: inputting ultrasonic energy into a proximal segment of the element at a driving frequency that excites a longitudinal resonance in the element; and generating lateral subharmonic vibrations in the distal tip segment in addition to longitudinal vibrations.

[0029] The ultrasonic excavation guidewire of this invention differs from other ultrasonic leads and conventional guidewires in many important respects.

[0030] This invention facilitates the navigation of guide wires through anatomical structures, lesions, and open lumens with a diameter larger than that of the guide wire or ball or any other enlarged feature at the distal end of the guide wire. For this purpose, a tapered or narrower distal portion of the guide wire may remain exposed to facilitate lateral excavation in the distal region. In conventional guide wires and in competing ultrasound guidewires, the distal end of the guide wire tapers to a narrower diameter to aid in navigation through tortuous anatomical structures. However, these portions of the guide wire are fitted with spring-like coils and / or polymer jackets to allow such flexible elements to be pushed through the anatomical structure.

[0031] In existing lead wires, the coils or clips allow for the transmission of longitudinal loads and can have the secondary function of maintaining a constant diameter along the length of the lead wire so that subsequent treatment devices introduced into the vascular system via a guidewire can do so at their maximum working length. However, in the ultrasonic lead wire of the present invention, the energy in the form of an ultrasonic displacement waveform transmitted through the lead wire provides a means for the lead wire to pass through obstructions, and therefore a coil or clip in the distal portion of the lead wire is not necessary.

[0032] To provide lateral tapping of blocking materials, the absence of a distal coil or jacket and the optimization of tapered and distal pad (land) lengths and diameters in this invention provide dual tapping of cavitation, abrasion, and ablation through longitudinal and lateral displacement of the conductor. In addition to the longitudinal direction, this invention also allows for preferential selection of subharmonics in the lateral or radial directions.

[0033] To select the subharmonic frequency to be mined in lateral mode at the distal end, the distal portion of the conductor is machined according to the invention to accommodate the preferred primary subharmonic resonant frequency. This is achieved by designing the conductor's profile relative to its taper and the length and diameter of its distal pad, thereby maximizing the lateral displacement of the distal portion.

[0034] For a given material with characteristic acoustic properties at 37°C selected for its elasticity, toughness, and mechanical properties, the optimal properties of the wire relative to its total length are an odd multiple (n = 1, 3, 5, ... n) of λ / 4, where λ is the wavelength in the material for a given input frequency and specific material properties.

[0035] The tapered transition provides a step gain or amplification of the ultrasonic energy transmitted distally in the conductor. However, the inventors have noted that the natural selection of the dominant subharmonic can be achieved by making the tapered length λ / 2. It has also been found that optimal lateral transmission of the conductor is obtained with a distal pad length λ.

[0036] An important aspect determining usability is that the conductors of the present invention have tip flexibility, allowing them to conform to the shape of the artery or other vessel they navigate, and are flexible such that lateral oscillation modes significantly affect force displacement. Therefore, conductors with a distal pad diameter of 0.005" to 0.008" are preferred, with 0.007" providing optimal performance in Type 1 Nitino conductors having a specific Af (e.g., between 5°C and 18°C).

[0037] It is necessary to utilize the displacement modes established by the excitation in both the longitudinal and lateral directions without exposing the conductor to high stress or strain levels that could lead to catastrophic conductor breakage. Therefore, the conductor is mechanically coupled to the ultrasonic transducer and is primarily excited in the longitudinal direction at a prescribed frequency and displacement amplitude. The conductor geometry is chosen such that it resonates primarily in a longitudinal mode at or near this input drive frequency, which establishes standing waves along the conductor's length at resonance. This results in a significant longitudinal component of vibration near the distal tip.

[0038] Another challenge is that while lateral displacement modes can occur anywhere along the length of the conductor, it is desirable to transfer and concentrate energy at the distal end. Specifically, in addition to the longitudinal modes at or near the system drive frequency, various additional longitudinal subharmonics exist, under which a conductor of suitable length for dissection will be excited. Furthermore, the conductor exhibits lateral or transverse vibration modes near the longitudinal dominant frequency and subharmonic frequencies. Any offsets or imbalances introduced by the anisotropy of the conductor or its construction or geometry will promote these lateral vibration modes, especially if these lateral modes are at or near the longitudinal modes. However, it is desirable to encourage lateral excitation to occur preferentially in the distal region of the conductor.

[0039] Lateral displacements occur at frequencies below the driving or input frequency, and the attenuation or amplification of these lateral displacements on the conductor's movement depends primarily on the driving frequency and the geometry and materials used in the conductor. These lateral modes are superimposed on the longitudinal motion in the distal region and, according to the invention, can be preferentially selected by incorporating specific design features into the conductor. While these lateral displacements may theoretically exist within the conductor, the selection of specific frequencies and vibration modes can be achieved by customizing the conductor's geometry (including the location and length of the taper), and the magnitude of the movement can be determined by the diameter and material properties of the distal portion of the conductor.

[0040] The conductor needs to be optimized to displace with optimal force and displacement to excavate blockages. Therefore, in the optimized conductor of this invention, different taper lengths and pad configurations along the conductor length can produce different lateral and longitudinal responses in the distal region of the conductor. These responses can then be optimized for different use cases envisioned in different anatomy and types of lesions.

[0041] There is also a need for a guidewire capable of rapidly navigating to and penetrating chronic total occlusions composed of calcified lesions, and thus providing a sufficiently large lumen to allow access to subsequent treatment devices via the lead. Therefore, the object of the present invention is to selectively excavate endovascular obstructive material and open a hole or lumen substantially larger than the cross-sectional area of ​​the lead to facilitate the delivery of subsequent therapies. For this purpose, the excavation mechanism in the distal tip region of the lead includes a direct longitudinal vibration coupled to a lateral movement that acts uniformly to ablate and open the lumen within the lesion. This ablation or other excavation mechanism can occur not only where the distal tip of the lead contacts the lesion, but also where the distal region of the lead contacts the lesion after the initial penetration.

[0042] According to the present invention, various interrelated variables can be modified to optimize lesion detection. Specifically, the lead wire guides ultrasound energy from the location where it is coupled to the transducer to the distal end of the lead wire. The detection of this distal tip region of the lead wire is determined by the pattern (i.e., lateral and longitudinal movement) and amplitude of the energy presentation in the lead wire, and is therefore determined by: the driving frequency and amplitude of the ultrasound signal / displacement driving the lead wire through its length; the acoustic transmission characteristics in the lead wire; and the diameter of different sections of the lead wire, namely the proximal pad section, the intermediate tapering section, and the distal pad section, which affects the amplification and amplitude of the lead wire displacement in different regions along the length of the lead wire when the lead wire responds to excitation.

[0043] Therefore, the size and consistency of a conductor affect its response in the following aspects: the internal composition of the conductor and the properties of its material; the external shape of the conductor and any discontinuities or shape features or formations in the conductor; the consistency of the conductor in its shape and size, such as length tolerances; taper dimensions, transition sections and their correlation with the applied ultrasonic energy; the variation of the conductor diameter from its proximal diameter at the transducer to the diameter of its distal excavation pad; the amplification associated with the diameter reduction over the length of the conductor; and the location and length of the taper section and how it corresponds to the wavelength.

[0044] The selection of the mechanical properties and design of the conductor to optimize its performance is based on the understanding that these properties are related to the physical behavior of lateral or transverse motion.

[0045] All these objectives of the present invention must be achieved by a guide wire with sufficient flexibility to determine the shape of the anatomical structures it traverses in use. Specifically, the flexibility and elasticity or resilience of the guide wire determine whether it can be fitted into the lumen of an artery or other blood vessel. The diameter and mechanical strength of the guide wire also determine whether it can pass through or navigate through tortuous anatomical structures and thus follow the shape of the blood vessel without congestion, blockage, or worse, penetration of the vessel wall due to its inability to deflect and conform to the shape of the anatomical structure. In this respect, in the case of the femoral artery, the vessel is large and therefore the ability of the guide wire to conform to its shape is less challenging than in foot arteries, for example, which have a tortuosity similar to that of the coronary arteries and some larger neurovascular anatomy.

[0046] The design parameters of each conductor can be jointly selected to control how much energy is coupled to the longitudinal and lateral modes. In a preferred embodiment, the ratio of the diameter of the proximal segment defining the working length of the conductor to the diameter of the distal segment defining the excavation section of the conductor is between 2:1 and 3:1, which provides optimal gain or amplification.

[0047] The optimal length of the tapered section used to select the primary and secondary frequencies is λ / 2, that is, the ratio of the length of the tapered section to the length of the far pad is λ / 2:λ, where the effective length of the conductor from the coupler to the far tip is an odd multiple of λ / 4 ((2n+1)λ / 4).

[0048] The lead is an example of an elongated intravascular element of the present invention that can be used as a waveguide or wave delivery system. For example, the element can be a hybrid of a lead and a catheter. In particular, the proximal portion of the element, such as the first meter from the proximal end, can have a lead encapsulated in a manner similar to a catheter, while the distal portion of the element extending to the distal end can be an unencapsulated lead. The lead or other element of the present invention can be an internal component of the entire wave delivery system.

[0049] The design of the transmission components or waveguide wires is optimized to control the transmission of wave patterns through different anatomical structures to the distal tip and through different materials. The morphology of the materials used is important, and while they can exhibit highly elastic isotropic material morphology at the "macro" level, they can also possess anisotropic micromorphological features that can delay the initiation of cracks or inhibit crack progression.

[0050] The materials used in the embodiments are widely cold-workable stainless steel, nickel-titanium alloys, and / or cobalt / chromium alloys, such as linearly elastic nickel-titanium. Specifically, in the case of nickel-titanium alloys only, the size and amount of inclusions are strictly controlled to limit the possibility of fracture. In other alloys, other morphological characteristics that may promote premature conductor failure are controlled.

[0051] This invention allows for the introduction of specific features machined into the conductor at the proximal and distal ends and along its length to enhance the conductor's ability to pass through lesions, strengthen the conductor, achieve greater control over the conductor, enable conductor coupling, and facilitate efficient transmission through the conductor. The composition of the design varies depending on the materials used and the intended application.

[0052] The geometry of the conductors and the materials used are optimized for different application use cases. The conductors are processed to minimize defects and optimized for transfer along the length of the material and through segments of the material length via tightly controlled taper and keyed splines. Attached Figure Description

[0053] Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0054] Figure 1 This is a schematic perspective view of the ultrasonic lead system according to the present invention.

[0055] Figure 2 This is a perspective view of the handheld ultrasonic activation unit and the lead wire with positioning marks.

[0056] Figure 3 This is a schematic side view of the conductor according to the present invention.

[0057] Figure 4 This is an enlarged side view of the distal portion of the conductor according to the present invention.

[0058] Figure 5 This is an enlarged view of the distal portion of the conductor in a variant of the present invention.

[0059] Figure 6 and 6a This is a side view of the conductor of the present invention, showing the response of the conductor to excitation.

[0060] Figure 7 It is a schematic side view of an active conductor with an angularly offset distal portion.

[0061] Figure 8a and Figure 8b This is a schematic side view of the additional active conductor including the marking strip of the present invention.

[0062] Figure 9 This is a schematic side view of another active conductor according to the present invention.

[0063] Figure 10 and 11 This is a schematic side view of the other active wires of the present invention, each having an enlarged spherical distal tip.

[0064] Figure 12This is a side view of the conductor of the present invention, showing the effect of adding a clip to the conductor.

[0065] Figure 13a , 13b 13c and 13c are schematic perspective views illustrating the ends of the wires in a variant of the invention.

[0066] Figure 14a , 14b 14c are schematic perspective views illustrating the end of a wire in a further variant of the invention. Detailed Implementation

[0067] The attached image Figure 1 The overall configuration of the system according to the invention is shown, and some of the main components of such a system are illustrated. This example features a handheld ultrasound activation unit 2, with a flexible delivery member in the form of an intravascular guide 4 extending through the handheld ultrasound activation unit in a centrally aligned manner.

[0068] Lead 4 can be inserted into the patient's vascular system and passed through to bring its distal end to the lesion site. Upon encountering a complex lesion that obstructs the passage of lead 4, activation unit 2 can be coupled to lead 4 at a suitable longitudinal position. When activated, activation unit 2 transmits ultrasonic vibrations to lead 4 and along it, thereby enhancing lead 4's ability to pass through the lesion through ablation and other mechanisms. Lead 4 thus serves as a crossing lead for passing through blockages in blood vessels and can then be held in place to serve as a guidewire for delivering subsequent treatment devices to treat the lesion.

[0069] Typically, the length of the lead 4 can be greater than 2 m and at most 3 m. For example, accessing or traversing a lesion in the foot may involve the lead traveling a distance of typically 1200 mm to 2000 mm within the vascular system, depending on whether an ipsilateral, contralateral, or radial approach is chosen. In this regard, the lead 4, which tapers distally at its tip, can navigate to the foot artery and encircle the arch of the foot between the dorsal and plantar arteries. However, the invention is not limited to foot or other peripheral applications and can be used, for example, in coronary artery applications, where the ability of the lead 4 to navigate to and excavate within tortuous small-diameter arteries is also advantageous.

[0070] The diameter of the distal segment of conductor 4 will determine the flexibility of conductor 4 and its ability to readily conform to the shape of the anatomical structures it is intended to traverse. Thus, for example, in tortuous (foot or coronary) anatomy, a distal segment with a diameter of 0.005" to 0.007" combines flexibility with the ability to excavate obstructive material.

[0071] Activation unit 2 includes user controls 6 and optionally a display. Activation unit 2 further includes a distal manual lasso 8, which a user can rotate about the central longitudinal axis of unit 2 and conductor 4. Specifically, activation unit 2 can slide on conductor 4 and can be coupled to conductor 4 at multiple longitudinally spaced locations by applying torque to rotate lasso 8. For coupling, lasso 8 acts on a coupling element such as a collet within activation unit 2, surrounding and coaxial with conductor 4. When lasso 8 is tightened, the collet clamps conductor 4 to deliver ultrasonic energy from an integrated ultrasonic transducer within activation unit 2, optionally via an amplifier horn coupled to the transducer. In some embodiments, conductor 4 can be directly coupled to the transducer, in which case the horn can be omitted.

[0072] The lasso 8 is reversible to release the activation unit 2 from the wire 4. Therefore, the wire 4 can be interchanged with different sizes, configurations, or materials for different purposes. The transducers or horns within the activation unit 2 can also be interchanged.

[0073] Figure 1 The disassembled arrangement is shown, in which the ultrasonic signal generator 10 is separated from the activation unit 2. In this example, the ultrasonic signal generator 10 is connected to the activation unit 2 via a connector cable 12. In an alternative arrangement, the ultrasonic signal generator 10 may be incorporated into the housing of the activation unit 2. Figure 1 The example shown has an externally powered ultrasonic signal generator 10, and therefore includes a power cable 14 connected to an external power source. Alternative embodiments may be powered by an internal battery, which may be incorporated, for example, into the ultrasonic signal generator unit 10 or the activation unit 2.

[0074] Typically, the system components are preferably portable, and more preferably handheld. These components may be wireless, rechargeable, reusable, and recyclable. Any external cables 12, 14 used for transmitting power or signals may be coupled via slip rings to allow free rotation of the cables 12, 14 and prevent tangling with the conductor 4, or the external cables may provide conduits for the proximal portion of the conductor 4.

[0075] The semi-automatic control system can control or modulate signals from generator 10 based on feedback from the lead-tissue interaction. These signals are applied to the transducers and corners of activation unit 2 and thus to the crossing lead 4, in order to control the transmitted signals to adjust for losses due to damping or increased resistance or modulation of the applied force. Visual and tactile feedback indicators can provide the user with visual, auditory, and / or tactile feedback regarding the device status, the nature of the ablated tissue, and indicate the level of force that can be applied to achieve tissue ablation and destruction, as well as the progress through the lead.

[0076] The system may include a device for providing manual over-control to help control the amplitude of the vibration delivered to the distal tip. This allows the system to be controlled by a user operating the device during surgery via controllers and user input mechanisms located on the generator and transmission unit, or to be autonomously controlled.

[0077] As will be explained, the distal end of lead 4 is also suitably optimized to track through anatomical structures in ultrasound imaging mode, and has a marking band to highlight the location under X-ray. The lead may have radiopaque markings to indicate the working length and the lead's passing tip.

[0078] Figure 2 The diagram illustrates how the conductor 4 is etched or otherwise marked with a series of optimal zone markings 92 to guide the user in selecting the length of conductor 4 that encourages distal activation. The user can then align the coupling of the activation unit 2 with the zone markings 92 on the conductor 4, optionally using other markings appropriately located on the housing 18 of the activation unit 2. This method is applicable to both through-through embodiments where the proximal portion of the conductor 4 is axially exposed from the housing 18 of the activation unit 2 and other embodiments where the proximal portion of the conductor 4 is laterally exposed along the length of the housing 18.

[0079] Marker 92 addresses a challenge in system control: how ultrasound energy is coupled to the lead wire and the importance of positioning the connection point in a specific area for optimal coupling. Marker 92, placed on the proximal segment of lead wire 4, ensures this alignment is clear to the physician. These marks 92 also facilitate the physician's reconnection of activation unit 2 to lead wire 4 at different locations during surgery.

[0080] To address the visibility and alignment of the excitation, marker 92 can be aligned with a reference point on the active unit 2, such as a reference point on the strain relief feature at the distal end of housing 18, to indicate an optimal location. Visualization of marker 92 can be improved by adding illumination and / or a transparent or semi-transparent window to the active unit 2, for example, positioned on the distal strain relief feature of unit 2.

[0081] Markings 92 can be easily applied by laser etching beads or other methods such as applying a coating and / or a jacket to mark the surface of conductor 4 in a way that allows users to distinguish the optimal connection points along the length of conductor 4. Modifying the oxide surface layer or the finish of conductor 4 is considered the best way to achieve this. The period or longitudinal spacing of these markings will be λ / 2, and the length of the markings will be a function of the efficiency of coupling energy into conductor 4, as well as its mechanical and dimensional properties.

[0082] In an embodiment of the invention, a mark 92 on the conductor 4 can indicate that any length of a plurality of lengths of the conductor 4 exposed from the housing 18 of the activation unit is at or near the resonant length and the proximal section is not at the resonant length. In other words, the attachment mark 92 is optimally positioned on the conductor 4 such that, when coupled to a sound source, the length of the distal portion from the coupling point to the distal tip is equal to the resonant length, while the length of the proximal portion from the coupling point to the proximal tip is equal to the non-resonant length. In practice, these marks 92 can be located in positions tailored to the system to account for bending and other design features that may affect the resonant response.

[0083] When using ultrasound energy to excite lead 4, it is desirable to optimize the displacement amplitude at the distal tip of the lead to detect lesions. Conversely, it is desirable to minimize the displacement or movement of the proximal end of the lead, which is outside the patient's body and can actually be freely suspended proximally from the activation unit 2.

[0084] To achieve this, the distal length of the wire 4 from the distal tip to the location where the activation unit 2 is coupled to the wire 4 should be an odd multiple of a quarter wavelength of the ultrasound. This will generate a standing wave in the wire and an antinode at the distal tip, thus maximizing the amplitude of the vibration at the distal tip.

[0085] Therefore, positioning the distal end of the transducer at an odd multiple of a quarter wavelength from the distal tip of conductor 4 will maximize vibration at the distal tip. Conversely, ensuring that the length of the proximal section is a multiple of half the wavelength from which the transducer is fixed will minimize vibration at the proximal end of conductor 4.

[0086] When coupled to the ultrasonic transducer 20 in the activation unit 2, the conductor 4 of the present invention undergoes axial ultrasonic vibration and can be considered as a fixed free rod under longitudinal or axial vibration. The natural frequency of the fixed free rod under longitudinal or axial vibration is given by the following expression:

[0087]

[0088] Where c = the speed of sound in the conductor material;

[0089] L is the length of the rod; and

[0090] ω = the system's natural frequency = 2πf

[0091] The ultrasonic activation unit 2 applies a constant, known frequency, and the sound velocity c of the conductor 4 can be measured experimentally or approximated by the following expression:

[0092]

[0093] Where E = Young's modulus of the conductor material; and

[0094] ρ = density of the conductor material

[0095] For systems using constant or near-constant frequencies, the length L of the conductor 4 where resonance will occur is given below:

[0096]

[0097] In fact, in the through-wire system, from the connection point of conductor 4 to the transducer, conductor 4 can be considered as two fixed free rods undergoing longitudinal axial vibration. One rod extends distally, and the other rod extends proximally from the activation unit 2.

[0098] For example, the speed of sound for a specific nickel-titanium alloy is approximately 3400 m / s. For a drive frequency of 40 kHz, the wavelength λ can be calculated to be approximately 85 mm. Therefore, the resonant length can be determined and marked at an optimal position on conductor 4. The wavelength further influences the selection of the taper position and taper length along conductor 4.

[0099] Figures 3 to 7 Various preferred and optional features of wire 4 are shown.

[0100] Typically, the lead wire 4 has features that allow it to be integrated with the handheld activation unit 2. For example, location markings are provided to guide optimal positioning and attachment of the activation unit 2, facilitating attachment and release at multiple longitudinal locations. Thus, along a considerable length of its proximal segment, a series of optimal attachment locations are etched or otherwise marked on the lead wire 4 to guide the user in positioning and selecting the optimal attachment location for distal ultrasound delivery from the activation unit 2. The housing 18 of the activation unit 2 may also have markings that can be aligned with the markings on the lead wire 4 prior to coupling.

[0101] As with all intravascular leads, a balance needs to be struck between flexibility or "traceability" and rigidity or "maneuverability." However, unlike passive leads, the lead must be able to deliver ultrasound energy to the distal region to aid in lesion penetration. In this way, lead 4 functions as a digger not only at its tip but also along a portion of its length. Lead 4 has a distal pad length that radially serves as a lateral digging device for opening the aperture. The lead may have a distal shaping length to amplify radial digging.

[0102] Conductor 4 includes regions with a geometrically tapered shape to influence diameter changes (from a larger diameter to a smaller diameter or from a smaller diameter to a larger diameter). In areas requiring tapering and other locations, sections can be welded or otherwise joined end-to-end. In addition to normal bending and cyclic fatigue patterns, such welds or joints must also be able to withstand stresses generated by ultrasonic energy transfer. Alternatively, the entire conductor 4 or portions of conductor 4 can be ground or similarly processed to achieve the desired geometry.

[0103] Therefore, wire 4 can be made from segments welded together end-to-end. For example, the proximal segment can be machined to a standard diameter to provide enlargement and a standard connection for the activation unit 2 loaded to the proximal side. The proximal segment can be welded to one of a selection of wires with different diameters that can have customized distal ends and distal tips. Thus, segments can be selected and combined in a variety of ways. This advantageously reduces the requirement to maintain raw materials with a variety of wire diameters, as several segments with different wire diameters can be assembled to produce wire 4 with many desired configurations. Welding the proximal segment to the distal segment, if post-processing is performed on the wire, promotes more efficient manufacturing and more efficient transport, and different materials can be welded to the proximal NiTi base if desired.

[0104] Ideally, the taper can be chosen to begin at a length equal to or nearly equal to a multiple of half the wavelength of the conductor system. This places the taper's starting point at the antinode of the standing wave in conductor 4, where the vibration amplitude is greatest. Preferably, the length of the taper section is chosen to be equal to or nearly equal to half the wavelength of the resonant system. Typically, the solder joint or connector should be located in the longitudinal position of least stress. Because the solder joint or connector is in a low-stress location, the load applied to it during conductor activation will not lead to catastrophic fatigue failure.

[0105] Figure 3 The conductor 4 shown includes a proximal segment 124, a central or intermediate segment 128, and a distal excavation segment 130 for traversing the lesion. The intermediate segment 128 is narrower than the proximal segment 124 but wider than the distal segment 130. Therefore, the intermediate segment 128 is connected to the proximal segment 124 via a tapered proximal transition 132 and to the distal segment via a tapered distal transition 134. Each segment is soldered to the next segment via a solder point 122 on the proximal side of its respective transition.

[0106] The proximal segment 124 has a series of longitudinally spaced region markers 92, similar to Figure 2The regions within the wire are marked to guide the user in selecting wire lengths that encourage distal activation and inhibit proximal activation. Wire 4 further includes radiopaque marker strips 136 to aid in tracking the intermediate segment 128 and distal segment 130 within the patient's anatomy during surgery. These various markers 136 are readily produced by plasma vapor deposition, atomic layer deposition, or sputtering (e.g., sputtered gold) to resist ultrasound loading.

[0107] Although essentially flexible to bend along their length, the proximal section 124, intermediate section 128, and distal section 130 are generally straight and aligned with each other along the central longitudinal axis of the conductor. However, the composite distal portion 138 of the conductor 4 has a shape configured to bend away from the overall axis of the conductor 4 in the remainder of the distal section 130. In addition to the longitudinal movement of the conductor 4, these bending or heat-set shapes also enhance lateral movement.

[0108] Specifically, as well as Figure 4 As shown, the distal portion 138 includes an inner angled leg 140 and an outer distal tip 126 at the distal end of the angled leg 140. The leg 140 is inclined relative to the overall axis of the conductor 4, and the distal tip 126 is inclined relative to the angled leg 140. The distal tip 126 may be as follows: Figure 4 The spherical or otherwise enlarged feature of 25 shown in the figure, and the coating 142 may extend partially along the length of the angled leg 140, leaving the distal end and distal tip 126 of the angled leg 140 uncoated.

[0109] In this example, the distal tip 126 is tilted further away from the overall axis of the conductor 4 than the angled leg 140. Therefore, both the distal tip 126 and the angled leg 140 are tilted in approximately the same direction away from the overall axis of the conductor 4. However, in other examples, the distal tip 126 is tilted closer to the overall axis of the conductor 4 than the angled leg 140. Potentially, the distal tip 126 may even be approximately parallel to the overall axis of the conductor 4 in the remainder of the distal segment 130.

[0110] To briefly reiterate, the total length of the distal portion of the wire 4 from the distal tip 126 to the connection point or coupling of the activation unit 2 can be equal to the resonant length of the wire 4. Ideally, the tapered length is equal to a multiple of half the wavelength. In addition to allowing standard-sized downstream devices to use the wire 4 as a guidewire, the diameters of the various segments of the wire 4 are selected to achieve an optimal balance between maneuverability and trackability.

[0111] In this example, lead 4 includes an angled portion positioned at the location to enhance maneuverability of lead 4 when tracing the lesion site. For example, the length of the angled leg 140 can be 15 mm to 25 mm and the length of the distal tip 126 can be 2 mm to 5 mm. The angled leg 140 facilitates steering through anatomical structures, while the distal tip 126 facilitates tracing through small-diameter lesions. The angle between the angled leg and the remainder of the distal segment 130 is typically 10° to 40°. This angle provides a means of navigation into the branch but is not large enough to promote stress exceeding the fatigue limit of lead 4. The angle between the distal tip 126 and the angled leg 140 is typically 10° to 30°. This allows navigation within diseased small-diameter vessels.

[0112] The wire 4 can be heat-treated, for example by annealing after machining the tip 126 and shaping it, to optimize its microstructure to resist fatigue.

[0113] The visibility of the lead 4 under X-ray or other imaging modes can be enhanced by adding a radiopaque marking strip or coating 136, which is selected to optimize visibility under optimal imaging modes. The lead 4 may also have a coating 142, such as a hydrophilic coating, to reduce friction with surrounding catheters or tissues.

[0114] Figure 5 The conductor 4 is shown to have a distal coil or polymer jacket 144 attached or bonded to the distal segment 130. The jacket shown here terminates distally just before a bend in the conductor 4 that facilitates deflection of the distal tip 126. The distal tip 126 of the conductor 4 may be coated or treated to harden the surface or increase its ablation properties.

[0115] Figure 6 and 6a The diagram shows a generally straight proximal segment or pad 124, a distally tapering intermediate segment 130, and a distal tip portion 126 for a conductor 4 passing through the generally straight excavation portion or pad of the lesion. Due to the tapering of the intermediate segment 130, the diameter of the distal tip portion 126 is smaller than that of the proximal segment 124. For example, the diameter of the proximal segment 124 can be 0.43 mm and the diameter of the distal tip portion 126 can be 0.18 mm or 0.25 mm. The tapering of the intermediate segment 130 is small and is therefore greatly exaggerated in these figures. The tapering intermediate segment 130 can extend to a length that is a multiple of λ or a fraction of λ, preferably having a numerator of 1 and an even denominator, such as in the sequence 1 / 2, 1 / 4, 1 / 8... while the length of the distal tip portion 126 can be λ / 2 or a multiple of λ / 2 or a fraction of λ / 2, such as λ / 4.

[0116] The overall geometry of conductor 4, including its nominal diameter and length, as well as the driving frequency of the system, is determined by the characteristic sound velocity in the conductor material. This characteristic is a function of the material's properties and its geometry. The dimensions of the conductor's straight and tapered sections are machined at functional intervals corresponding to wavelengths.

[0117] As an example of a nickel-titanium alloy with a Young's modulus of approximately 75 GPa, λ, λ / 2, and λ / 4 are determined to be 84 mm, 42 mm, and 21 mm, respectively. The selected frequencies will generate harmonics along the conductor length, and the load at the conductor tip will help establish standing waves for non-characteristic lesions. The distal segment 126 can be tapered or can be uniform in diameter along its length. The system can generate lateral and longitudinal displacements in a frequency range far from the driving frequency, typically occurring at subharmonic frequencies in the distal segment 126.

[0118] As an example, without excluding other dimensional values, a conductor with a core cross-sectional diameter of 0.43 mm has a tapered section 130, which is optimally positioned to transition to a distal conductor diameter of 0.18 mm. The length of each section of the conductor can be selected to have a longitudinal resonant mode at or near the driving frequency, such as 40 kHz, and strong subharmonics at or near 20 kHz, 10 kHz, or other frequencies. With proper design, adjacent lateral modes exist at 40 kHz and 20 kHz or other nearby frequencies. The tapered section may be larger than approximately 2.4 times or other suitable values. When the conductor is exposed from the conduit or sheath, additional low-frequency lateral vibrations may occur through cantilever action.

[0119] Therefore, by appropriately selecting the conductor material, geometry, and distal design features, ideal lateral modes can be excited even when the conductor is driven by longitudinal vibration. Simultaneously, both longitudinal and lateral vibrations contribute to the discovery of lesions and cause the conductor to open holes or cavities within the lesions, where the inner diameter of the lesion is significantly larger than the conductor diameter.

[0120] In terms of length, the total length of the conductor can be a function of an odd multiple of λ / 4. The effective length, which is the distance from the proximal connection point to the distal tip of the conductor, can also be a function of an odd multiple of λ / 4.

[0121] The purpose of the tapered transition 130 is to provide gain and maintain energy transfer through the conductor. The tapered section will also affect how lateral displacement patterns are established in the distal pad section 126 of the conductor.

[0122] Introducing taper points can also help promote material variation between parts of the conductor, which may create wavelength differences between the distal and proximal segments.

[0123] The diameter of the tapering transition can vary in a stepped, exponential, radial, or linear manner. For amplification purposes, the change in cross-sectional area represents the gain level of both lateral and longitudinal displacement amplitudes in the conductor. The length and diameter of the distal segment 126 will determine the pattern and amplitude of displacement in the axial and radial directions.

[0124] Since the goal of the activated wire 4 is to pass through and excavate lesions, its size is optimized to excavate the largest possible hole given the input. In this respect, Figure 6 The distal segment 126 of conductor 4, once activated, moves in a primary longitudinal mode, moving in and out, and also moves radially, which maps out and excavates a larger volume at the distal end through the longitudinal movement of conductor 4. The distal segment 126 of conductor 4 is also seen moving laterally and wavyly at or near the drive frequency and in a differential harmonic secondary mode, depending on the activation frequency and the length of the distal segment 126. These waveforms may interfere with each other and excavate material more or less effectively at different times.

[0125] Figure 6 Further illustration shows how the distal segment 126 of lead 4 can excavate a hole with a diameter larger than that of the lead, thereby creating a larger lumen through which therapy can be introduced into the lesion. In this example, the catheter cannula or polymer clip 144 again terminates before the un-clipped distal segment 130 of the lead. Once activated, the distal segment 126 of lead 4 moves in a primary longitudinal mode, moving in and out, and also moves in the radial direction, which maps out and excavates a larger volume at the distal end through the longitudinal movement of lead 4. It is also seen that the distal segment 126 of lead 4 moves in other modes through lateral and wavy motions in the secondary modes of resonant wave 146 and differential harmonics, depending on the activation frequency, the length of the distal segment, and the tortuosity of the anatomical structure.

[0126] Therefore, when activated with ultrasonic energy, lead 4 acts as a digging tool by means of longitudinal movement, and then by the displacement translation or lateral movement of lead 4 within the vascular system providing lateral displacement, to dig out material distal to the distal tip of lead 4. Thus, lead 4 abrades the obstructed inner surface not only at its distal tip but also along its length extending proximally from the distal tip, and thus forms a wider orifice for access to subsequent treatment devices through lead 4. As lead 4 extends beyond the distal end of the lesion, lateral displacement continues digging within the lesion, and thus forms a larger lumen.

[0127] Figure 7A guide 4 is shown, formed or shaped to have an angled distal excavation segment for crossing the lesion. In this embodiment, the distal segment is not straight but angled due to a heat-set shaped tip 126. The dimensions of the tip 126 are optimized to provide improved performance in manipulating and excavating the lesion. Specifically, the angle of the tip 126 relative to the longitudinal axis of the distal segment and the length of the tip 126 determine the ability of the guide 4 to transition into a particular collateral vessel. The angle and length of the tip 126 also affect how the guide 4 will excavate a segment of stenotic material once activated. If the dimensions of the tip 126 are of a harmonic characteristic, for example, λ / 8 or a length of approximately 11 mm, the guide 4 will open a significantly larger tunnel in the lesion than, for example, a 25 mm tip segment. The amplitude of the waveform and the number of times the distal segment of the guide 4 crosses the calcified segment will determine the diameter of the tunnel excavated.

[0128] The wire 4 does not necessarily need to be shaped or angled at its tip, but if it is, the angle must be carefully chosen. If the angle of the tip 126 is too large, it will create a larger lever arm and thus cause excessive fatigue in the wire 4; conversely, if the angle of the tip 126 is too small, the wire 4 may not be able to be manipulated effectively. In this respect, Figure 7 The tip 126 can be offset from the longitudinal axis of the conductor 4 by approximately 15° to 45°, thereby allowing the tip 126 to disrupt and excavate lesions of a larger volume. The tip 126 is suitably heat-treated, for example, at over 500°C for less than 10 minutes, to produce a microstructure that reliably resists crack propagation and thus fatigue.

[0129] Figure 8a and 8b This illustrates how the visibility of the lead 4's position in the patient's body can be enhanced by using a marking strip 194, such as gold. For example, such a marking strip 194 can be secured near the distal tip 126 of the lead 4 (e.g., approximately 3 mm away) and also away from the distal end of the proximal segment 184, just before the start of the tapering intermediate segment 186. The marking strip 194 is positioned at the point of least load when using the lead 4. This minimizes the possibility that the marking strip 194 can be removed or that the lead 4 might fail at these locations. The marking strip 194 can be easily flush-fitted into a circumferential groove ground around the lead 4.

[0130] Figure 9 A variation is shown in which the distal tip 126 of conductor 4 is rounded without a sharp transition. As an example, in this case, the proximal segment 184 can be 1800 mm long, the tapered intermediate segment 186 can be 84 mm long, and the distal segment 188 can be 10 mm long. Again, the marking strip 194 surrounds conductor 4 near the distal tip 126 and the distal end of the proximal segment 184.

[0131] Figure 10 and 11 Other variations of the conductor 4 are shown, each having a spherical distal tip 198, which is rounded to avoid a sharp transition, but can instead be chamfered or have facets, preferably with obtuse angles between the facets, having facets that converge distally to simplify the passage of the conductor through the anatomical structure. An enlargement, such as a light bulb, can be located at and / or slightly spaced from the distal tip, and can cover a non-transmissive coil or other material.

[0132] The length of the spherical tip 198 can be, for example, 3 mm to 4 mm, and the diameter can be just over 0.4 mm, or, for example, 0.010" to 0.035". In addition to its spherical tip 198, Figure 10 The wires shown are otherwise similar Figure 9 The wire 4 is shown in the diagram. Similarly, Figure 10 and 11 The wire 4 shown has a circumferential marking strip 194, which can be flush-fitted into a circumferential groove ground around the wire 4. Conveniently, as shown, a spherical tip 198 can be surrounded by one of the marking strips 194.

[0133] exist Figure 11 In the example shown, the conductor has a proximal portion comprising a straight section 200 and a distally tapering section 202. The straight section 200 may have a ridged or other textured surface as shown to improve engagement with the activation device. The proximal portion is soldered to a middle portion constituting most of the length of the conductor 4. The middle portion also includes a straight section 204 and a short distally tapering section 206. A marking band 194 is shown as the distally tapering section 206 surrounding the straight section 204 near the middle portion 194. Finally, a short, narrow distal section 208 extends distally from the middle portion 186 to the spherical tip 198.

[0134] Figure 12 This demonstrates how, for example, using a polymer jacket or coil 144 to jacket or thickly coat a lead can keep the desired distal length open or unjacketed and allow for lateral free oscillation as shown in the figure. The effect of a jacket or coating can also be simulated by a conduit surrounding the lead 4. It has been found that the distal extent of the jacket controls the hole created by the distal excavation section 130 of the lead 4. The lead 4 excavates the lesion distal to the jacket 144 up to the loop or edge 148. It has been found that if the unjacketed distal length of the lead is not long enough, it may create a hole at the lesion that is no larger than the diameter of the lead, or even inhibit the progression of the lead through the blockage.

[0135] Specifically, the conductor 4 is fitted with a sleeve at a length below or above the resonant or harmonic length, such that the distal edge 148 of the sleeve 144 does not coincide with the resonant or harmonic length, thereby hindering the formation of the hole. Conversely, the conductor 4 is fitted with a sleeve to the resonant or harmonic length, such that the distal edge 148 of the sleeve 144 is substantially aligned with the resonant or harmonic length, thereby allowing the conductor 4 to create a larger hole.

[0136] Figure 13a , 13b Figures 13c and 13c show the arrangement of the distal tip 126. Figure 13a A wire 4 is shown, which is surrounded by a non-transparent band 136 and has a circular cow-shaped tip 150, such as beryllium. Figure 13b A non-transmittable coil 151 is shown welded around the distal tip section 126 of the conductor 4. Figure 13c An oversized beryllium tip 152 is shown to increase effectiveness when traversing long calcified sections. The distal tip section 126 can be heat-treated to increase its fatigue resistance.

[0137] Figure 14a , 14b Figures 14c show other arrangements of the distal tip 126. Figure 14a A ring-shaped tip 154 ​​with an outer surface is shown, which is coated or otherwise modified to optimize drilling or excavation along the loop, rather than being confined to the tip. The loop can also aid in navigation to blockage locations. Figure 14b The diamond-coated tip burr 156 is shown. Figure 14c A drill tip 158 or segment coated with a diamond and / or carbide coating is shown. Coatings and hardening materials, such as these, provide positive processing of the lesion.

[0138] Typically, the conductor 4 of this invention is readily made of a superelastic alloy, such as nitinol (nickel-titanium), which is known to have preferential properties in ultrasonic transmission while providing a balance between flexibility and maneuverability. Linearly elastic nitinol, resulting from advancements in the processing of nickel and titanium alloys, can also be used for the conductor of this invention; β-titanium is also an option. Surface finishes and coatings applied to the conductor 4 may include elastic fluoropolymers and hydrophilic coatings to reduce friction.

[0139] Many other variations are possible within the scope of this invention. For example, the coating can be provided along discrete segments of the conductor, such as by coating intermediate sections of the conductor's length so that the distal and proximal portions of the conductor are uncoated for use in excavation and for clamping the activation unit, respectively. Continuous and discontinuous coated segments along the length of the conductor can allow for selective clamping and removal of the activation unit at desired locations.

[0140] PTFE or alternative polymer jackets can be used to reduce the risk of friction and damage to the inside of the guiding catheter.

[0141] Polymer jackets can be used in the distal section to improve radiation impermeability, more generally to provide lubrication along the conductor, or to provide markers for connection to the transducer of the activation unit.

[0142] Surface modification can involve adding striations or serrations to the surface of the distal portion to further penetrate the calcified lesion, thereby aiding in excavation and resistance to damage. Such formations can be directional to utilize the direction of movement and amplify the cutting or abrasion efficiency of the obstructing material. However, individual formations can have smooth rather than sharp contours to avoid damaging the vessel wall. Similarly, materials can be applied to the lead to create additional abrasive surfaces to aid in material excavation. Such materials can usefully reduce the area of ​​the lead in contact with the lesion to facilitate cutting and prevent calcified material from impeding the vibration and movement of the lead.

[0143] A stretched filled tube (DFT) can be used, in which a NiTi core is surrounded by a second metal with different properties, such as stainless steel. Because the relative thickness of the second layer can be controlled, it can be used to create marking strips, couple wires, shape wires, or promote lateral damping.

[0144] The jacket of the shaped alloy can provide navigation and / or opacity. Using a more ductile outer jacket can avoid the need for cold working and post-treatment heat treatment of Nitinol.

[0145] Potentially, there may be multiple cut surfaces defined by multiple pads located at the distal tip or distal region of the conductor. This can facilitate different and potentially more anatomically appropriate distal gains, as well as a potentially larger diameter second proximal pad for better lesion handling. This is one way to create multiple lateral excavation zones; other methods include different cross-sectional diameters, different tapers, and different excavation pad profiles.

[0146] It should be noted that many features of the various embodiments described above are not limited to those specific embodiments. Those skilled in the art will be able to combine features from one embodiment with features from other embodiments, provided that this is technically possible and makes sense from a practical point of view.

Claims

1. An elongated intravascular element for passing through an obstruction in a blood vessel, said element comprising: Proximal section; The distal tip segment has a diameter smaller than that of the proximal segment; as well as A distally tapering intermediate section extends between the proximal section and the distal tip section. The length of the tapered intermediate segment is either λ / 2 in the sequence λ / 2, λ / 4, λ / 8... or a multiple of λ / 2 or a fraction with an even denominator of λ / 2, where λ is the wavelength of the driving frequency that will produce longitudinal resonance in the element. The proximal segment of the element is marked with a series of longitudinally spaced position marks, which are spaced apart from each other by a distance of λ / 2, to guide the user to couple the activation unit in order to optimally activate the distal tip segment.

2. The element according to claim 1, wherein the length of the distal tip segment is λ / 2 or a multiple of λ / 2, where λ is the wavelength of the driving frequency that will produce longitudinal resonance in the element.

3. The element according to claim 1 or 2, wherein the diameter of the distal tip segment is between 1 / 8 and 1 / 2 of the diameter of the proximal segment.

4. The element according to claim 1 or 2, wherein its total length is a function or multiple of (2n+1)λ / 4, where λ is the wavelength of the driving frequency that will produce longitudinal resonance in the element.

5. The element according to claim 1 or 2, wherein the length of the proximal segment is λ / 4 + nλ / 2, where λ is the wavelength of the driving frequency that will produce longitudinal resonance in the element.

6. The element according to claim 1 or 2, wherein the length of the proximal segment is an odd multiple of λ / 4, where λ is the wavelength of the driving frequency that will produce longitudinal resonance in the element.

7. The element according to claim 1 or 2, wherein the distal tip segment includes a spherically enlarged feature at the distal end.

8. The element according to claim 1 or 2, wherein the distal tip segment includes a distal portion that is angularly offset relative to the longitudinal axis of the element.

9. The element according to claim 1 or 2, wherein the marking band at least surrounds the distal tip segment.

10. The element according to claim 1 or 2, wherein the distal tip section is tapered or has a constant diameter along its length.

11. The element according to claim 1 or 2, wherein the length of each segment of the element is a function or multiple of λ / 4, where λ is the wavelength of the driving frequency that produces longitudinal resonance in the element.

12. The element according to claim 1 or 2, further comprising a marking band positioned on the distal tip portion and near the distal end of the proximal segment.

13. The element according to claim 1 or 2, wherein the distal tip portion is partially clipped or coated or partially covered by a conduit, such that the length of the element extending to its distal tip is un-clipped or uncoated.

14. The element according to claim 1 or 2, wherein the middle section of the length of the element is clipped or coated, and at least a portion of the proximal section is not clipped or coated.

15. The element of claim 14, wherein the proximal segment has a discontinuous, longitudinally discontinuous jacket or coating.

16. The element according to claim 1 or 2, wherein at least the distal portion of the distal tip segment comprises a bare wire without a sheath or coating.

17. An intravascular device for passing through an obstruction in a blood vessel, the device comprising an elongated intravascular element according to any one of the preceding claims and an ultrasonic transducer mechanically coupled to the element to ultrasonically excite the distal tip segment of the elongated intravascular element to facilitate passage through the obstruction.

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