Catheter for treating calcified plaque

Abstract

A catheter for treating calcified plaque includes a catheter body and an expandable balloon. Therapeutic devices of the catheter disrupt and / or alter the calcified plaque. The treatment device can be a thermal shock generator, a nuclear magnetic resonance generator or a vibration generator.

Description

Technical Field

[0001] The present technology generally relates to a catheter and method for treating calcified plaques within the body of a subject. Background Art

[0002] A variety of techniques and instruments have been developed for the percutaneous treatment of calcified plaques within the body of a subject. By way of example, calcified plaques may accumulate within the circulatory system of a subject. A common example is the accumulation of fatty deposits (atheromas) within the intimal layer (located beneath the endothelium of the patient's blood vessels). Over time, a substance that was initially deposited as a relatively soft cholesterol-rich atherosclerotic material typically hardens into a calcified atherosclerotic plaque. An atheroma may be referred to as a stenosis lesion or stenosis, while the occluding substance may be referred to as a stenotic substance. If left untreated, such stenosis can severely reduce perfusion, which may lead to angina, hypertension, myocardial infarction, stroke, etc. Angioplasty or atherectomy may be performed to improve blood flow. However, the presence of calcified plaques typically makes it difficult to adequately treat the blood vessel. Summary of the Invention

[0003] The technology of the present disclosure generally relates to altering and / or disrupting calcified plaques.

[0004] In one aspect, the present disclosure provides a catheter for treating calcified plaques within the body of a subject. The catheter includes a catheter body having opposite proximal and distal end portions and a longitudinal axis extending between the proximal end portion and the distal end portion. The catheter body is configured to be percutaneously inserted into the body of the subject and delivered to a treatment site having a calcified plaque. An expandable balloon is coupled to the distal end portion of the catheter body. The expandable balloon is configured to contact the calcified plaque and apply a radial pressure thereto. A thermal shock generator is operably coupled to the expandable balloon and is configured to alternate between heating and cooling the calcified plaque to induce a thermal shock in the calcified plaque.

[0005] In another aspect, the present disclosure provides a method for treating a calcified plaque at a treatment site within the body of a subject. The method includes: delivering the catheter body of the catheter to the treatment site such that the balloon at the distal end portion of the catheter body is adjacent to the calcified plaque; expanding the balloon after delivering the catheter body to apply a radial pressure to the calcified plaque; heating the calcified plaque; and rapidly cooling the heated calcified plaque to induce a thermal shock in the calcified plaque while the radial pressure is applied to the calcified plaque by the expandable balloon.

[0006] In yet another aspect, the present disclosure provides a catheter for treating calcified plaque within a subject's body. The catheter includes a catheter body having opposite proximal and distal end portions and a longitudinal axis extending between the proximal end portion and the distal end portion. The catheter body is configured to be percutaneously inserted into the subject's body and delivered to a treatment site having calcified plaque. A magnetic resonance generator includes a radio frequency coil coupled to the distal end portion of the catheter body. The magnetic resonance generator is configured to disrupt the calcified plaque.

[0007] In yet another aspect, the present disclosure provides a catheter for treating calcified plaque within a subject's body. The catheter includes a catheter body having opposite proximal and distal end portions and a longitudinal axis extending between the proximal end portion and the distal end portion. The catheter body is configured to be percutaneously inserted into the subject's body and delivered to a treatment site having calcified plaque. A vibration generator located at the distal end portion of the catheter body is configured to generate radial mechanical vibrations that are adapted to produce resonance in the calcified deposits within the calcified plaque, thereby disrupting the calcified deposits.

[0008] Details of one or more aspects of the present disclosure are set forth in the following drawings and description. Other features, objects, and advantages of the techniques described in this disclosure will be apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a schematic diagram of an embodiment of a catheter for treating calcified plaque.

[0010] Figure 2 is a schematic cross-section of the catheter body of the catheter.

[0011] Figure 3 is a schematic diagram of the catheter within a body cavity including calcified plaque, with the balloon of the catheter in a deflated state.

[0012] Figure 4 is similar to Figure 3 , where the balloon is in an inflated state and receives heated fluid therein to heat the calcified plaque.

[0013] Figure 5 is similar to Figure 4 , except that cooled fluid is delivered to the balloon to rapidly cool the calcified plaque.

[0014] Figure 6 is an exemplary scheme of a control unit for operating the catheter.

[0015] Figure 7 is another embodiment of a catheter for treating calcified plaque using thermal shock treatment.

[0016] Figure 8 is another embodiment of a catheter for treating calcified plaque using nuclear magnetic resonance.

[0017] Figure 9 is similar to Figure 8 Another embodiment of the catheter.

[0018] Figure 10 is another embodiment of a catheter for treating calcified plaque using nuclear magnetic resonance.

[0019] Figure 11 is an embodiment of a catheter for treating calcified plaque using mechanical vibration.

[0020] Figure 12 is Figure 11 The enlarged distal end portion of the catheter.

[0021] Figure 13 is another embodiment of a catheter for treating calcified plaque using mechanical vibration.

[0022] Figure 14 is Figure 13 The enlarged distal end portion of the catheter.

[0023] Figure 15 is the enlarged distal end portion of another embodiment of a catheter for treating calcified plaque using mechanical vibration.

[0024] Figure 16 is the enlarged distal end portion of yet another embodiment of a catheter for treating calcified plaque using mechanical vibration. Detailed Description

[0025] The following description generally relates to embodiments and examples of a therapeutic catheter for treating calcified plaque within a subject's body. The examples shown are applicable to treating calcified plaque within a subject's circulatory system (such as the subject's blood vessels and / or heart). The examples shown may also be applicable to treating other body cavities external to the circulatory system.

[0026] Referring to Figure 1 , one embodiment of a therapeutic catheter for treating calcified plaque within a subject's body is generally designated by reference numeral 10. Generally, the catheter 10 is configured to create a thermal shock in the calcified plaque. The thermal shock alters or destroys the calcified plaque. For example, the thermal shock can cause the calcified plaque to rupture, thereby facilitating treatment. In one example, the calcified plaque can be further treated, such as by angioplasty or endarterectomy or other treatments, or the treatment using the thermal shock can be the primary or sole treatment of the calcified plaque.

[0027] Still referring to Figure 1, the catheter 10 includes a catheter body 12 having a proximal end portion and a distal end portion and a longitudinal axis extending between the proximal end portion and the distal end portion. The catheter body 12 is designed and configured to be percutaneously inserted into a blood vessel of a subject to deliver the distal end portion of the catheter body to a treatment site including a calcified plaque. As a non-limiting example, the catheter body 12 may have a length of about 135 cm to about 142 cm and a diameter of about 138 mm to about 142 mm. The catheter body 12 may suitably include a flexible material, such as a polymer, to enable the body to traverse a tortuous path to the treatment site.

[0028] The thermal shock generator 14 of the catheter 10 is configured to heat (i.e., transfer heat to) the calcified plaque and then rapidly cool the calcified plaque (i.e., remove heat from the calcified plaque) to create a thermal shock within the calcified plaque. In the present embodiment, the thermal shock generator 14 is fluidly connected to an expandable heat transfer element 18 at the distal end portion of the catheter body. The thermal shock wave generator 14 includes a heating system (generally designated 20) in thermal communication with the heat transfer element, a cooling system (generally designated 24) in thermal communication with the heat transfer element, and a control unit 26 that controls the operation of the heating system and the cooling system. As explained in more detail below, the heating system 20 is configured to generate heat and transfer the heat to the heat transfer element, which in turn transfers the heat to the calcified plaque at the treatment site. The cooling system 24 is configured to rapidly remove heat from the transfer element, which in turn rapidly removes heat from the calcified plaque at the treatment site. In other words, the cooling system 24 is configured to rapidly cool the calcified plaque. The control unit 26 is configured to control the timing and amount of heating and cooling of the calcified plaque to create a thermal shock within the plaque, as Figure 6 shown.

[0029] In the illustrated embodiment, the expandable heat transfer element 18 is an expandable balloon configured to receive a heat-conducting fluid to inflate the balloon. The inflated balloon 18 contacts the calcified plaque and applies a radial pressure or force thereto. The inflated balloon 18 also facilitates heat transfer between the plaque and the inflated balloon. The wall of the balloon 18 is heat-conductive to facilitate heat transfer from the heat-conducting fluid to the balloon wall and from the balloon wall to the calcified plaque. Suitable fluids for the balloon 18 include, but are not limited to, saline. Suitable balloon materials include, but are not limited to, nylon. Also in the illustrated embodiment, a guidewire lumen 19 extends along the catheter body 12 and through the balloon 18 for receiving a suitable guidewire (not shown).

[0030] Reference Figure 1 and Figure 2, in the illustrated embodiment, the heating system 20 includes: a heating fluid lumen 30 that extends along the catheter body 12 from the proximal end portion into the interior of the balloon 18; a return heating lumen 32 that extends along the catheter body from the interior of the balloon toward the proximal end portion; a fluid heater 34; and a fluid circulator 36 that is configured to circulate the heated fluid between the fluid heater and the heating fluid lumen and the return lumen. The fluid heater 34 can be a conventional heater for heating the fluid, such as by conduction or otherwise. The fluid circulator 36 is configured to deliver the heated fluid through the heating fluid lumen 30 and into the balloon 18, thereby heating the calcified plaque on the balloon, for example, by conduction. The fluid is recirculated back through the return lumen 32 to be reheated and delivered to the balloon 18. The temperature of the fluid as it enters the balloon 18 can be from about 150°C to about 160°C. As explained below, a temperature sensor 40 (e.g., a thermocouple) can be disposed in, on, or otherwise in thermal communication with the balloon. The temperature sensor 40 communicates (e.g., wired or wirelessly) with the control unit 26 to monitor the temperature of the fluid. In the illustrated embodiment, a wire 42 ( Figure 2 ) connects the temperature sensor 40 to the control unit 26.

[0031] , in the illustrated embodiment, the cooling system 24 includes: a cooling fluid lumen 50 that extends along the catheter body 12 from the proximal end portion into the interior of the balloon 18; a return cooling lumen 52 that extends along the catheter body from the interior of the balloon toward the proximal end portion; a fluid chiller 54 that is disposed external to the patient's body; and a fluid circulator 56 that is configured to circulate the cooled fluid between the fluid chiller and the cooling fluid lumen and the return lumen. The fluid chiller 50 can be a conventional chiller for cooling the fluid, such as by conduction or otherwise. The fluid circulator 56 is configured to deliver the cooled fluid through the cooling fluid lumen 50 and into the balloon 18, thereby rapidly cooling the calcified plaque, for example, by conduction. The fluid is recirculated back through the return lumen 52 to be recooled and delivered to the balloon 18. The temperature of the fluid as it enters the balloon 18 can be from about -20°C to about -40°C. As described below, the temperature sensor 40 that communicates (e.g., wired or wirelessly) with the control unit 26 is used to monitor the temperature of the fluid. As described below, the calcified plaque can be rapidly cooled in other ways.

[0032] Reference Figure 3 , in one example, the distal end of the catheter body is delivered to the treatment site such that the balloon 18 in its deflated state is adjacent to the calcified plaque. Then, the user can interact with the control unit 26 via the user interface 60 (e.g., a touch screen) such that the control unit actuates the treatment protocol. In one example, as Figure 4As shown, the control unit enables the heating system 20 by enabling the heater and the circulator to inflate the balloon and heat the balloon. The control unit monitors the temperature inside the balloon or of the balloon or of the calcified plaque through feedback from the temperature sensor 40. In one example, the balloon wall is heated to a temperature of about 150°C to about 300°C. When a heating threshold temperature signal from the temperature sensor 40 indicating that the balloon wall has reached the desired temperature persists for a desired amount of time, the control unit 26 actuates the delivery of the cooling fluid to rapidly cool the balloon 18 and the calcified plaque (or remove heat from the balloon and the calcified plaque), as Figure 5 shown. Before the control unit 26 operates the circulator 56, the cooling fluid may have been pre-cooled so that the cooled fluid immediately replaces the heated fluid to achieve rapid cooling. In one example, the balloon wall cools at a rate of about -20°C / s to about -40°C / s. The control unit 26 may stop the circulation of the cooled fluid when a threshold cooling temperature signal from the temperature sensor 40 persists for a desired amount of time. In one example, the threshold cooling temperature signal may indicate that the balloon wall has reached a temperature of about -38°C to about -40°C.

[0033] In one example, the control unit 26 may be programmed to operate the heating system 20 and the cooling system 24 to perform repeated heating and cooling of the calcified plaque and repeated application of the radial force from the balloon 18. Figure 6 An example of a suitable scenario is shown, where the solid line indicates temperature and the dashed line indicates the pressure imposed by the balloon. The heating and subsequent rapid cooling of the calcified plaque together with the pulsed radial pressure cause ruptures (e.g., stress fractures) within the calcified plaque, and the inflated balloon applies radial stress to the plaque. This combination of treatments alters or disrupts the plaque. After treatment with the catheter 10, in one example, the catheter body 12 may be withdrawn and subsequent treatments (e.g., angioplasty and / or atherectomy and / or drug therapy) may be performed.

[0034] It should be understood that the operation of the heating system 20 and the cooling system 24 may be reversed such that the cooling system is enabled first and then the heating system is enabled.

[0035] Reference Figure 7 , another embodiment of a treatment catheter for treating calcified plaques in a subject's body is generally designated by the reference numeral 110. Generally, the catheter 110 is similar to the catheter 10 in that this catheter is configured to create a thermal shock in the calcified plaque. The thermal shock alters or disrupts the calcified plaque. For example, the thermal shock can cause the calcified plaque to rupture, facilitating treatment. In one example, the calcified plaque may be further treated, such as by angioplasty or atherectomy or other treatments, or the treatment using the thermal shock may be the primary or sole treatment for the calcified plaque.

[0036] In this embodiment, the catheter 110 includes a catheter body 112 and a cryoballoon 114 at a distal end portion of the catheter body, the cryoballoon being configured to rapidly cool calcified plaque. As is commonly known in the art, the cryoballoon 114 includes a refrigerant released within the balloon to rapidly cool the inflating fluid in the balloon. The cryoballoon 114 contacts the calcified plaque to rapidly cool the plaque. Generally, the cryoballoon 114 includes a cooling system in which the fluid in the balloon is cooled within the balloon rather than the fluid being cooled away from the balloon and then delivered to the balloon. The catheter 110 includes a control unit 126 for controlling the cooling of the calcified plaque using the cryoballoon 114.

[0037] The illustrated embodiment also includes a plaque heating element 130 within or adjacent to the balloon for non-conductive heating of the calcified plaque. Generally, the plaque heating element 130 is part of a heating system of the catheter 110. The plaque heating element 130 can be an ultrasound transducer for generating ultrasound energy directed at the calcified plaque. The ultrasound energy is absorbed by the calcified plaque to heat the plaque. In another embodiment, the plaque heating element 130 can be a radio frequency generator configured to heat the calcified plaque by dielectric heating. The plaque heating element 130 can be other types for non-conductive heating. The control unit 136 communicates with the plaque heating element 130 to operate the heating element.

[0038] In one example, the control unit 126 can be programmed to operate the cryoballoon 114 and the heating element to perform repeated heating and cooling of the calcified plaque and repeated application of a radial force from the balloon 118. Figure 6 An example of a suitable scenario is shown where the solid line indicates temperature and the dashed line indicates the pressure imposed by the balloon. The heating and subsequent rapid cooling of the calcified plaque together with pulsed radial pressure cause rupture (e.g., stress rupture) within the calcified plaque, and the inflated balloon applies a radial stress to the plaque. This combination of treatments alters or disrupts the plaque. After treatment with the catheter 110, in one example, the catheter body 112 can be withdrawn and a subsequent treatment (e.g., angioplasty and / or atherectomy and / or drug treatment) can be performed.

[0039] Reference Figure 8 Another embodiment of a treatment catheter for treating calcified plaque within a subject's body is generally designated by reference numeral 210. Generally, the catheter 210 is configured to use nuclear magnetic resonance (NMR) to alter or disrupt calcified plaque. In one example, the calcified plaque can be further treated, such as by angioplasty or atherectomy or other treatments, or the treatment catheter 210 can be the primary or sole treatment for the calcified plaque.

[0040] The catheter 210 includes a catheter body 212, an NMR generator (generally designated 216) coupled to the distal end portion of the catheter body, and a control unit 226 in communication with the NMR generator. The catheter body 212 is designed and configured to be percutaneously inserted into a blood vessel of a subject to deliver the distal end portion of the catheter body to a treatment site including a calcified plaque. As a non-limiting example, the catheter body 212 can have a length of about 132 cm to about 142 cm and a diameter of about 17 mm to about 20 mm. The catheter body 212 can suitably comprise a flexible material, such as plastic, to enable the body to traverse a tortuous path to the treatment site.

[0041] The illustrated NMR generator 216 includes at least one magnet 232 (broadly, a constant magnetic field generator) and at least one radio frequency (RF) coil 234 (broadly, an oscillating magnetic field generator) adjacent to the magnet. The magnet 232 generates a magnetic field that polarizes molecules in the calcified plaque. The magnet 232 can be a permanent magnet as Figure 8 illustrated, or an electromagnet 232' as Figure 9 illustrated. The RF coil 234 generates an oscillating magnetic field at the Larmor frequency of calcium to cause the molecules to "relax". This relaxation of the molecules disrupts the calcium in the calcified plaque. The control unit 226 controls the operation of the RF coil to generate the Larmor frequency.

[0042] Referring Figure 10 , in another embodiment similar to the catheter 210, the catheter 310 includes an RF coil 334 (broadly, an oscillating magnetic field generator) controlled by a control unit 326, but does not include a magnet. Instead, a contact magnetic field is generated outside the subject's body, such as by an MRI machine.

[0043] Referring Figure 11 and Figure 12 , another embodiment of a treatment catheter for treating a calcified plaque within a subject's body is generally designated by reference numeral 410. Generally, the catheter 410 is configured to use vibrational energy to alter or disrupt the calcified plaque. In one example, the calcified plaque can be further treated, such as by angioplasty or atherectomy or other treatments, or the treatment catheter 410 can be the primary or sole treatment for the calcified plaque.

[0044] The catheter 410 includes a catheter body (generally designated 412), a vibration generator 416 disposed in an expandable cage (generally designated 418), and a control unit 426 in communication with the vibration generator. The catheter body 412 is designed and configured to be percutaneously inserted into a blood vessel or other body cavity of a subject to deliver the expandable cage 418 to a treatment site including calcified plaque. As a non-limiting example, the catheter body 412 can have a length of from about 132 cm to about 142 cm and a diameter of from about 17 mm to about 20 mm. In the illustrated embodiment, the catheter body 412 includes a retractable sheath 430 and an inner shaft 432 coupled to the expandable cage 418.

[0045] The vibration generator 416 is configured to generate mechanical vibrations. In one example, the vibration generator 416 includes a piezoelectric actuator, such as a piezoelectric cylinder or tube actuator configured to generate radial vibrations. The piezoelectric actuator 416 can have, for example, an outer diameter of from about 1.5 mm to about 0.5 mm. An electrical energy source 436 (e.g., a voltage source) is electrically connected to the piezoelectric actuator, such as through one or more electrical conductors 438( Figure 12 ). The electrical energy supplied to the vibration generator 416 can be controlled or manipulated by the control unit, which can include a microprocessor and / or a pulse width modulator. The control unit 426 can be configured to send control signals to the piezoelectric actuator 416 to generate mechanical vibrations. The control signals delivered to the piezoelectric actuator 416 can be pulse width modulated, or the parameters of the control signals can be otherwise adjusted by the control unit 426. In one example, the control unit 426 is configured (e.g., programmed) to deliver a range of voltages to the piezoelectric actuator 416 to generate vibrations within a certain frequency range, as explained in more detail below. The electrical energy source 436 and / or the control unit 426 can be housed within the handle or can be separate from the handle.

[0046] The vibration generator can include other types of vibration generators suitable for generating mechanical vibrations. For example, reference Figure 13 and 14, the vibration generator 516 of another catheter embodiment 510 may include a rotatable mass. In one example, the rotatable mass 516 is configured to generate vibrations when it reaches a particular rotational speed. In another example, the rotatable mass 516 may be an eccentric wheel. The rotatable mass 516 may be rotated by a drive shaft 537 (e.g., a drive coil) that is operatively connected to a motor 539 (e.g., an electric motor) to drive the drive shaft to rotate about its axis. The motor 539 may be controlled or operated by a control unit 526 that may include a microprocessor. The control unit 526 may be configured to control the speed of the motor 539 to generate mechanical vibrations at the rotatable mass 516. In one example, the control unit 526 is configured (e.g., programmed) to control the motor 539 to generate different rotational speeds, thereby generating vibrations across a frequency range, as explained in more detail below. The drive shaft 537 may extend through a lumen defined by an inner shaft 532. The rotatable mass 516 is housed within a housing 541 and may rotate relative to the housing. The rotatable mass 516 may be rotatably connected to the housing 541. The motor and / or control unit may be housed within the handle or may be separate from the handle.

[0047] For purposes of disclosure, the following features are discussed only with respect to catheter 410. However, unless otherwise indicated, the following disclosure equally applies to catheter 410, 510, or any other embodiment that includes one type of vibration generator.

[0048] Returning to Figure 11 and Figure 12 , the expandable cage 418 is configured to be received within a retractable sheath 430, which in turn is received within a guiding catheter 450. The retractable sheath 430 is retractable relative to the expandable cage 418. The expandable cage 418 includes a cage body 460 that includes a plurality of struts 462 or other structural members that are configured to enable the cage to self-expand when the cage is removed from the sleeve 430 (such as by retracting the sleeve). As an example, the cage body 460 may generally be in the form of a self-expanding stent. The cage body 460 may include metal (e.g., nitinol), polymer, or other materials suitable for transmitting mechanical vibrations or be formed therefrom. When expanded, the cage 460 radially engages calcified plaque L in the body (e.g., blood vessel BV). The illustrated cage 460 also includes a distal cap or cover 464 that is fixed to the cage body 460. The distal cap 464 is configured to capture tissue that detaches from the calcified plaque L during treatment to inhibit downstream embolization. The distal cap 464 may include a blood-permeable membrane or other materials suitable for capturing the detached tissue.

[0049] Referring to Figure 15, the expandable cage 618 of another catheter embodiment 610 may include needles or barbs 615 (e.g., microneedles) coupled to the cage body 660 and extending generally radially outward from the cage body. The needles 615 are configured to embed in the calcified plaque L when the cage 618 expands and to transmit mechanical vibrations from the cage body 660 into the calcified plaque. It is believed that this further facilitates the transmission of vibrations into the calcified plaque L. The needles 615 may have a length (or radial extent) of less than 1 mm, such as 0.5 mm, such that the needles do not penetrate the vessel wall, e.g., the vessel wall without calcified plaque. The needles 615 may be formed on the cage body 660 or otherwise directly coupled to the cage body (e.g., coupled to the struts 662 of the cage body). In another example, the needles 615 may be formed on a mesh or sleeve received on the expandable cage 618. As Figure 15 shown, when the cage 618 expands, the needles 615 may be angled toward the distal end of the cage body 660 to inhibit damage to the needles during tracking, deployment, and recapture of the expandable cage. The needles 615 may flex or deflect toward the cage body 660 during recapture and when received within the sheath 630 and rebound from the cage body when released from the sheath. The needles 615 may be formed of or include metal (e.g., stainless steel, nitinol, titanium) or polymer (e.g., polyimide, silicone) or other materials suitable for transmitting mechanical vibrations. In one example, the needles 615 may be configured to disconnect from the cage body 660 during recapture and remain in the calcified plaque L. The needles may be dissolvable or non-dissolvable.

[0050] Returning to reference Figure 11 and Figure 12 , in the illustrated embodiment, the proximal end portion and the distal end portion of the expandable cage 418 are coupled to the inner shaft 432. In the illustrated embodiment, the inner shaft 432 defines an inner guidewire lumen configured to receive a guidewire (not shown) to deliver the catheter 410 to a treatment site. In the illustrated embodiment, the vibration generator 416 is mounted on or otherwise coupled to the inner shaft 432 within the expandable cage 418. In one example, the inner shaft 432 passes through the vibration generator 416. For example, in the case where the vibration generator is the piezoelectric tube 416, the inner shaft 432 may pass through the tube. In other embodiments, the inner shaft 432 may be coupled to the piezoelectric tube 416 such that the lumen defined by the tube communicates with the lumen of the inner shaft 432 to together define a guidewire lumen. In another example, the rotatable mass 516 and the rotatable drive shaft 537 may include a lumen to define an inner guidewire lumen through which a guidewire is received.

[0051] Still referring to Figure 11 and Figure 12, the vibration generator 416 is operatively coupled to the cage 418, and more specifically to the cage body 460, via at least one transmission coupler 470, which is configured to transmit mechanical vibrations from the vibration generator 416 to the cage.( Figure 14 A similar transmission coupler 570 as shown in is coupled to the housing 541 and the cage to transmit vibrations from the rotatable mass 516.) The illustrated embodiment includes a plurality of elongated transmission couplers 470, which may be in the form of transmission struts that extend generally radially outward from the vibration generator 416 (or housing) to the struts 462 of the cage body 460. The transmission couplers 470 may extend at a non-vertical angle to the cage body 460.

[0052] Now, for illustrative purposes, referring to the catheter 410, it should be understood that the following disclosure equally applies to other embodiments unless otherwise indicated. In one example of use, the catheter 410 is delivered to the calcified plaque L through the guiding catheter 450. For example, the catheter 410 may be tracked along a guide wire received in the guide wire lumen of the catheter body 412. The catheter 410 may be delivered to the calcified plaque L in other ways. The retractable sheath 430 is retracted relative to the expandable cage 418 to release the expandable cage. When the sheath 430 is retracted, the cage 418 self-expands, whereby the cage body radially engages the calcified plaque L. In an embodiment including a needle 615( Figure 15 ), when the cage 418 expands, the needle embeds into the calcified plaque L. Then, the vibration generator 416 is activated to generate mechanical vibrations that are transmitted through the transmission coupler to the expandable cage 418 (and to the needle if applicable). The control unit 426 controls the frequency and / or amplitude of the generated vibrations and sweeps the vibration frequency to cause resonance in the calcified deposits CD( Figure 12 ) in the calcified plaque L. When the mechanical vibrations cause one or more calcified deposits CD to oscillate at the natural vibration frequency of the calcified deposits (its resonance frequency or resonant frequency), the calcified deposits respond with a greater amplitude of vibration. This increased amplitude causes the calcified deposits CD in the calcified plaque L to break, be destroyed, and / or be altered.

[0053] In one example, the vibrations generated by the vibration generator 416 (e.g., a piezoelectric actuator or a rotatable mass) may have a frequency ranging from about 10 kHz to about 1000 kHz and an amplitude ranging from about 10 microns to about 100 microns. The resonance frequency of hydroxyapatite (the main material in the calcified deposits) is 100 kHz to 280 kHz. Thus, in one example, the catheter 410 is configured to transmit mechanical vibrations within this frequency range (i.e., sweep this frequency range) to cause resonance and break the calcified deposits. The catheter 410 may be configured to transmit other frequency ranges. The control unit 426 is used to generate the frequency.

[0054] After treatment, the expandable cage 418 collapses when retracted into the retractable sheath 430 or alternatively when the sheath is moved distally to recapture the cage. When the cage 418 collapses, tissue detached from the calcified plaque L enters the expandable cage and is captured in the distal cap 464. The catheter 410 is then withdrawn from the body. Subsequent treatments (e.g., angioplasty and / or atherectomy and / or drug therapy) can then be performed.

[0055] Reference Figure 15 , in another embodiment, the catheter 710 does not include an expandable cage or other delivery component. Instead, the vibration generator 716 is configured to transmit vibrations through a body fluid (e.g., blood) in a body (e.g., a blood vessel). The vibration generator 716 can be delivered to the calcified plaque L such that the generator is radially spaced from the calcified plaque L (e.g., about 1 mm). Thus, the body fluid serves as a medium for transmitting mechanical vibrations to the calcified plaque L to cause resonance of the calcified deposits CD. The vibration generator 716 can be, for example, a piezoelectric tube or other vibration generator. Except for this difference, the operation of the catheter is similar to the previous embodiment, i.e., the catheter delivers vibrations to cause resonance of the calcified deposits in the calcified plaque, thereby causing the calcified plaque to break, rupture, or otherwise change.

[0056] By using a vibration generator to cause resonance of the calcified deposits in the calcified plaque, several benefits are achieved. For example, the catheter can prepare the calcified plaque for subsequent intervention by disrupting, altering the calcified plaque, and / or removing the calcified deposits from the calcified plaque. The catheter can use a single device to alter and remove the calcified deposits. The catheter can be compatible with a 0.014-inch guidewire and a 6F guiding catheter. When the expandable cage includes struts and thus openings, there is no blockage of the body cavity during treatment. In addition, using the catheter does not cause damage to healthy areas of the body cavity.

[0057] The present invention can also be described with reference to the following numbered paragraphs:

[0058] 1. A catheter for treating a calcified plaque in a subject's body, the catheter comprising:

[0059] A catheter body having opposite proximal and distal end portions and a longitudinal axis extending between the proximal and distal end portions, wherein the catheter body is configured to be percutaneously inserted into the subject's body and delivered to a treatment site having a calcified plaque;

[0060] An expandable balloon coupled to the distal end portion of the catheter body, wherein the expandable balloon is configured to contact the calcified plaque and apply a radial pressure thereto;

[0061] A thermal shock generator that is operably coupled to the expandable balloon and configured to alternate between heating and cooling the calcified plaque to induce a thermal shock in the calcified plaque.

[0062] 2. The catheter according to paragraph 1, wherein the wall of the expandable balloon is thermally conductive to transfer heat between the calcified plaque and the expandable balloon.

[0063] 3. The catheter according to paragraph 2, wherein the thermal shock generator includes: a heating system and a cooling system, the heating system being configured to deliver heated thermally conductive fluid to the balloon, and the cooling system being configured to deliver cooled thermally conductive fluid to the balloon.

[0064] 4. The catheter according to paragraph 3, wherein the heating system includes a heating circulator for circulating the heated thermally conductive fluid in and out of the balloon, and wherein the cooling system includes a cooling circulator for circulating the cooled thermally conductive fluid in and out of the balloon.

[0065] 5. The catheter according to paragraph 3, the catheter further including a control unit in communication with the heating system and the cooling system, wherein the control unit is configured to alternate between operating the heating system and operating the cooling system.

[0066] 6. The catheter according to paragraph 5, the catheter further including a temperature sensor configured to sense at least one of: the temperature inside the balloon, the temperature of the wall of the balloon, and the temperature of the calcified plaque, wherein the temperature sensor is in communication with the control unit.

[0067] 7. The catheter according to paragraph 2, wherein the thermal shock generator is configured to heat the wall of the balloon to a temperature of about 150°C to about 300°C, and to cool the wall of the balloon at a rate of about -20°C / s to about -40°C / s.

[0068] 8. The catheter according to paragraph 8, wherein the thermal shock generator is configured to cool the wall of the balloon to a temperature of about -38°C to about -40°C.

[0069] 9. The catheter according to paragraph 1, wherein the thermal shock generator includes a plaque heating element configured to non-conductively heat the calcified plaque.

[0070] 10. The catheter according to paragraph 9, wherein the plaque heating element includes an ultrasonic transducer.

[0071] 11. The catheter according to paragraph 9, wherein the plaque heating element includes a radio frequency generator.

[0072] 12. The catheter according to paragraph 9, wherein the plaque heating element is disposed in the balloon.

[0073] 13. The catheter according to paragraph 9, wherein the thermal shock generator is configured to deliver a refrigerant to the balloon to cool the balloon and the calcified plaque.

[0074] 14. The catheter according to paragraph 1, wherein the thermal shock generator is configured to deliver a refrigerant to the balloon to cool the balloon and the calcified plaque.

[0075] 15. A method of treating a calcified plaque at a treatment site within a subject's body, the method comprising:

[0076] delivering a catheter body of a catheter to the treatment site such that a balloon at a distal end portion of the catheter body is adjacent to the calcified plaque;

[0077] after delivering the catheter body, expanding the balloon to apply a radial pressure to the calcified plaque;

[0078] heating the calcified plaque; and

[0079] rapidly cooling the heated calcified plaque to induce a thermal shock in the calcified plaque while the radial pressure is applied to the calcified plaque by the expandable balloon.

[0080] 16. The method according to paragraph 15, wherein heating the calcified plaque comprises: delivering a heated thermally conductive fluid to the balloon.

[0081] 17. The method according to paragraph 15, wherein cooling the calcified plaque comprises: delivering a cooled thermally conductive fluid to the balloon.

[0082] 18. The method according to paragraph 15, wherein heating the calcified plaque comprises: non-conductively heating the calcified plaque using a plaque heating element coupled to the catheter body.

[0083] 19. The method according to paragraph 15, wherein cooling the calcified plaque comprises: introducing a refrigerant into the balloon to cool the balloon.

[0084] 20. A catheter for treating a calcified plaque within a subject's body, the catheter comprising:

[0085] a catheter body having opposite proximal and distal end portions and a longitudinal axis extending between the proximal and distal end portions, wherein the catheter body is configured to be percutaneously inserted into the subject's body and delivered to a treatment site having a calcified plaque;

[0086] An expandable balloon, which is coupled to the distal end portion of the catheter body, wherein the expandable balloon is configured to contact the calcified plaque and apply a radial pressure thereto;

[0087] A nuclear magnetic resonance generator, which includes a radio frequency coil located within the balloon, wherein the nuclear magnetic resonance generator is configured to disrupt the calcified plaque.

[0088] 21. A catheter for treating a calcified plaque within a subject's body, the catheter comprising:

[0089] A catheter body having opposite proximal and distal end portions and a longitudinal axis extending between the proximal and distal end portions, wherein the catheter body is configured to be percutaneously inserted into the subject's body and delivered to a treatment site having a calcified plaque; and

[0090] A vibration generator located at the distal end portion of the catheter body, the vibration generator being configured to generate radial mechanical vibrations that are adapted to produce resonance in the calcified deposits within the calcified plaque, thereby disrupting the calcified deposits.

[0091] 22. The catheter according to paragraph 21, further comprising an expandable cage located at the distal end portion of the catheter body, the expandable cage being configured to be expandable to radially engage the calcified plaque, wherein the vibration generator is operatively coupled to the expandable cage such that the mechanical vibrations generated by the vibration generator are transmitted to the expandable cage and, in turn, to the calcified plaque.

[0092] 23. The catheter according to paragraph 22, wherein the vibration generator is disposed within the expandable cage.

[0093] 24. The catheter according to paragraph 23, wherein the vibration generator is operatively coupled to the expandable cage by at least one transmission coupler.

[0094] 25. The catheter according to paragraph 21, wherein the vibration generator includes a piezoelectric actuator.

[0095] 26. The catheter according to paragraph 25, wherein the vibration generator includes a piezoelectric tube.

[0096] 27. The catheter according to paragraph 22, wherein the expandable cage includes a cage body that includes a plurality of struts.

[0097] 28. The catheter according to paragraph 22, wherein the expandable cage includes a plurality of needles configured to be embedded in the calcified plaque.

[0098] It should be understood that the various aspects disclosed herein can be combined in combinations different from those specifically presented in the specification and the drawings. It should also be understood that depending on the example, certain actions or events of any of the processes or methods described herein can be performed in a different order, can be added, combined, or omitted altogether (e.g., not all of the described actions or events may be required to perform these techniques). Additionally, although for clarity some aspects of the present disclosure are described as being performed by a single module or unit, it should be understood that the techniques of the present disclosure can be performed by a combination of units or modules associated with, for example, a medical device).

[0099] In one or more examples, the described techniques can be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions can be stored on a computer-readable medium as one or more instructions or code and executed by a hardware-based processing unit. The computer-readable medium can include a non-transitory computer-readable medium corresponding to a tangible medium such as a data storage medium (e.g., RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer).

[0100] The instructions can be executed by one or more processors such as one or more digital signal processors (DSPs), general-purpose microprocessors, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Thus, as used herein, the term "processor" can refer to any of the foregoing structures or any other physical structure suitable for implementing the described techniques. Additionally, these techniques can be fully implemented in one or more circuits or logic elements.

Claims

1. A catheter (10) for treating calcified plaques within a subject's body, the catheter (10) comprising: A catheter body (12) having opposite proximal and distal end portions and a longitudinal axis extending between the proximal and distal end portions, wherein the catheter body (12) is configured to be percutaneously inserted into the subject's body and delivered to a treatment site having a calcified plaque; An expandable balloon (18) coupled to the distal end portion of the catheter body (12), wherein the expandable balloon (18) is configured to contact the calcified plaque and apply a radial pressure thereto; A thermal shock generator (14) operatively coupled to the expandable balloon (18) and configured to alternate between heating and cooling the calcified plaque to induce a thermal shock in the calcified plaque.

2. The catheter (10) according to claim 1, wherein the wall of the expandable balloon (18) is thermally conductive to transfer heat between the calcified plaque and the expandable balloon (18).

3. The catheter (10) according to any one of claims 1 and 2, wherein the thermal shock generator (14) comprises: A heating system (20) and a cooling system (24), the heating system being configured to deliver heated thermally conductive fluid to the expandable balloon (18), the cooling system being configured to deliver cooled thermally conductive fluid to the expandable balloon (18).

4. The catheter (10) according to claim 3, the catheter further comprising a control unit (26) in communication with the heating system (20) and the cooling system (24), wherein the control unit (26) is configured to alternate between operating the heating system (20) to deliver heated thermally conductive fluid to the expandable balloon (18) and operating the cooling system (24) to deliver cooled thermally conductive fluid to the expandable balloon (18).

5. The catheter (10) according to claim 4, the catheter further comprising a temperature sensor (40) configured to sense at least one of: the temperature inside the expandable balloon (18), the temperature of the wall of the expandable balloon (18), and the temperature of the calcified plaque, wherein the temperature sensor (40) is in communication with the control unit (26).

6. The catheter (10) according to any one of claims 2 to 5, wherein the thermal shock generator (14) is configured to heat the wall of the expandable balloon (18) to a temperature of about 150°C to about 300°C and to cool the wall of the expandable balloon (18) at a rate of about -20°C / s to about -40°C / s.

7. The catheter (110) according to any one of claims 1 and 2, wherein the thermal shock generator (114) comprises a plaque heating element (130) configured to non-conductively heat the calcified plaque.

8. The catheter (110) according to claim 7, wherein the plaque heating element (130) is disposed within the expandable balloon (118).

9. A catheter (210) for treating calcified plaque within a subject's body, the catheter (210) comprising: A catheter body (212) having opposite proximal and distal end portions and a longitudinal axis extending between the proximal and distal end portions, wherein the catheter body (212) is configured to be percutaneously inserted into the subject's body and delivered to a treatment site having calcified plaque; A nuclear magnetic resonance generator (216) including a radio frequency coil (234) coupled to the distal end portion of the catheter body (212), wherein the nuclear magnetic resonance generator (216) is configured to disrupt the calcified plaque.

10. A catheter (410) for treating calcified plaque within a subject's body, the catheter (410) comprising: A catheter body (412) having opposite proximal and distal end portions and a longitudinal axis extending between the proximal and distal end portions, wherein the catheter body (412) is configured to be percutaneously inserted into the subject's body and delivered to a treatment site having calcified plaque; and A vibration generator (416) located at the distal end portion of the catheter body (412), the vibration generator (416) being configured to generate radial mechanical vibrations adapted to cause resonance in calcified deposits within the calcified plaque, thereby disrupting the calcified deposits.

11. The catheter (410) according to claim 10, the catheter further comprising an expandable cage (418) located at the distal end portion of the catheter body (412), the expandable cage (418) being configured to be expandable to radially engage the calcified plaque, wherein the vibration generator (416) is operatively coupled to the expandable cage (418) such that the mechanical vibrations generated by the vibration generator (416) are transmitted to the expandable cage (418) and, in turn, to the calcified plaque.

12. The catheter (410) according to claim 11, wherein the vibration generator (416) is disposed within the expandable cage (418).

13. The catheter (410) according to any one of claims 11 and 12, wherein the vibration generator (416) is operatively coupled to the expandable cage (418) by at least one transmission coupler (470).

14. The catheter (410) according to any one of claims 10 to 13, wherein the vibration generator (416) comprises a piezoelectric actuator.

15. The catheter (610) according to any one of claims 11 to 14, wherein the expandable cage (618) comprises a plurality of needles (6150 configured to be embedded in the calcified plaque.

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