The invention generally relates to balloon catheters for vascular intervention and particularly to devices for imaging from within a balloon.
Atherosclerosis, or hardened arteries, involves the buildup of plaque inside blood vessels. The buildup of plaque restricts the flow of blood, and thus nutrients and oxygen, to a person's tissue and brain. Sometimes chunks of the atherosclerotic plaque break away and flow through the person's blood vessels. This can lead to serious and deadly strokes and heart attacks.
Vascular balloon catheters are one tool for treating atherosclerosis. In a treatment known as balloon angioplasty, a catheter is used to inflate a balloon within the narrowed vessel to crush the plaque and open up the vessel. The balloon is then withdrawn, allowing blood to flow freely. The balloon may also be used to implant a stent to support the newly opened vessel.
Blood vessels have countless forks and turns, none of which are visible to the naked eye. Nevertheless, angioplasty requires maneuvering the catheter to the affected area and using the balloon in the right spot. Even though some catheters have imaging devices, maneuverability and visibility are significant problems. For example, each device on a catheter tends to stiffen the catheter and decrease its flexibility. Thus, adding an ultrasonic imaging probe near a balloon or stent interferes with maneuverability. Moreover, deploying the balloon in the correct location can require multiple iterations of viewing the affected site, sliding the catheter into position, inflating the balloon, pulling the catheter back to look again, and repeating. This trial-and-error approach requires the patient to have a catheter threaded into their veins for a prolonged time, which aggravates the patient's discomfort, as well as increasing costs and risks of complications.
The invention provides a balloon catheter with an imaging device inside the balloon and capable of viewing a treatment site through a wall of the balloon. Since this arrangement allows a physician to both view the affected site within the vessel and to inflate the balloon at the location that is in view, the device allows a balloon to be deployed in just the right location with a single inflation. Locating the imaging device inside of the balloon also minimizes a stiff length of the catheter. Due to its increased flexibility, the catheter is more maneuverable, and a doctor can more readily position the balloon properly at the treatment site. Since the doctor can view the treatment site directly through the balloon and deploy the balloon in the correct location, multiple iterations of catheter positioning are avoided. Since the balloon can be maneuvered to the correct location and deployed with precision and accuracy, treatment does not require a prolonged amount of time. Thus, patient discomfort and unnecessary costs as well as high risks of complications are all avoided. With these tools, more patients can be treated for atherosclerotic conditions that would otherwise pose a significant risk of stroke and heart attack.
In certain aspects, the invention provides a vascular balloon catheter generally having an elongate shaft with a proximal portion and a distal portion and having an inflatable balloon disposed at the distal portion for insertion into a vessel. An image detector is disposed within the balloon to take an image of the vessel and treatment site by receiving a signal through the balloon. The image detector can be located on the surface of the elongate shaft of the catheter and the elongate shaft can provide a guidewire lumen for angioplastic guidewire procedures. The image detector may include a fiber that is on an exterior of the elongate member within the balloon and entirely within the elongate shaft everywhere outside of the balloon. In some embodiments, the image detector uses an optical fiber, a photoacoustic transducer, or both. For example, the image detector can include a fiber Bragg grating. This can be used with a photoacoustic transducer to receive a signal through the balloon as sound and to send the signal from the balloon to the proximal portion of the catheter (e.g., along the optical fiber) as light. Where the image detector employs an optoacoustic imaging modality, acoustic energy may propagate substantially perpendicular to an axis of the catheter and light may propagate substantially parallel to the axis.
By using an optical fiber, positioning the image detector within the balloon, or both, a catheter may be provided that has imaging capabilities and also a substantially uniform flexibility everywhere along its length outside of the balloon.
In related aspects, the invention provides a method of delivering an angioplasty balloon by using an elongate catheter having a balloon disposed at a distal portion of the catheter to deliver the balloon to a treatment site within a vessel. The treatment site is viewed from within the balloon using an image detector on the distal portion within the balloon. An operator may decide when and where to inflate the balloon based on viewing the treatment site. Inflating the balloon causes an exterior surface of the balloon to make contact with the treatment site and dilate the vessel. Methods of the invention may also optionally be used to deliver and deploy a stent.
In some embodiments, the treatment site is viewed via ultrasound imaging technology, optical-acoustical imaging, or other suitable methods. For example, an ultrasound image signal may be received at the image detector and converted into an optical interferometric signal using the image detector. The image detector may employ one or more of an optical fiber; a fiber Bragg grating; a blazed fiber Bragg grating; photoacoustic transducer; other elements; or a combination thereof.
The invention generally relates to intravascular balloon catheters, and more particularly to a balloon catheter that provide the ability to capture an image from within the balloon.
Catheter 101 includes an angioplasty balloon 107 or other interventional device at distal portion 105 to expand or dilate blockages in blood vessels or to aid in the delivery of stents or other treatment devices. Blockages include the narrowing of the blood vessel called stenosis.
Typically, elongate shaft 111 of catheter 101 will include a guidewire lumen so that the catheter may be advanced along a guidewire. Guidewire lumen in a balloon catheter is described in U.S. Pat. No. 6,022,319 to Willard. Elongate shaft 111 may include any suitable material such as, for example, nylon, low density polyethylene, polyurethane, or polyethylene terephthalate (PET), or a combination thereof (e.g., layers or composites). An inner surface of a guidewire lumen may include features such as a silicone resin or coating or a separate inner tube made, for example, of preformed polytetrafluoroethylene (PTFE). The PTFE tube may be installed within the catheter shaft by sliding it into place and then shrinking the catheter shaft around it. This inner PTFE sleeve provides good friction characteristics to the guidewire lumen, while the balance of the catheter shaft can provide other desired qualities. Other suitable materials for use in catheter 101 or an inner tube portion thereof include high density polyethylene (HDPE) or combinations of material, for example, bonded in multiple layers.
Catheter 101 may include coaxial tubes defining separate inflation and guidewire lumens, for example, along a portion of, or an entirety of, a length of catheter 101. A plurality of lumens may be provided in parallel configuration or coaxial at one point and parallel at another, with a twisting/plunging portion to affect a transition between the parallel segment and the coaxial segment (see., e.g., U.S. Pat. No. 7,044,964). Other possible configurations include one or more of a guidewire tube or guidewire lumen disposed outside of the balloon. Or the guidewire tube may be affixed to and extend along the wall of the balloon.
In some embodiments, the balloon includes artificial muscle (electro-active polymer). Electro-active polymers exhibit an ability to change dimension in response to electric stimulation. The change may be driven by electric field E or by ions. Exemplary polymers that respond to electric fields include ferroelectric polymers (commonly known polyvinylidene fluoride and nylon 11, for example), dielectric EAPs, electro-restrictive polymers such as the electro-restrictive graft elastomers and electro-viscoelastic elastomers, and liquid crystal elastomer composite materials. Ion responsive polymers include ionic polymer gels, ionomeric polymer-metal composites, conductive polymers and carbon nanotube composites. Common polymer materials such as polyethylene, polystyrene, polypropylene, etc., can be made conductive by including conductive fillers to the polymer to create current-carrying paths. Many such polymers are thermoplastic, but thermosetting materials such as epoxies, may also be employed. Suitable conductive fillers include metals and carbon, e.g., in the form of sputter coatings. Electro-active polymers are discussed in U.S. Pat. No. 7,951,186; U.S. Pat. No. 7,777,399; and U.S. Pub. 2007/0247033, the contents of each of which are incorporated by reference.
As shown in
Imaging device 135 can employ any suitable imaging modality known in the art. Suitable imaging modalities include intravascular ultrasound (IVUS), optical coherence tomography (OCT), optical-acoustical imaging, and others. For ultrasound imaging, catheter 101 may include an ultrasound transducer as imaging device 135. Ultrasonic imaging catheters are discussed in U.S. Pat. No. 5,054,492 to Scribner; U.S. Pat. No. 5,024,234 to Leary; and U.S. Pat. No. 4,841,977 to Griffith. Systems for IVUS are discussed in U.S. Pat. No. 5,771,895; U.S. Pub. 2009/0284332; U.S. Pub. 2009/0195514; U.S. Pub. 2007/0232933; and U.S. Pub. 2005/0249391, the contents of each of which are hereby incorporated by reference in their entirety. OCT systems and methods are described in U.S. Pub. 2011/0152771; U.S. Pub. 2010/0220334; U.S. Pub. 2009/0043191; U.S. Pub. 2008/0291463; and U.S. Pub. 2008/0180683, the contents of each of which are hereby incorporated by reference in their entirety. In certain embodiments, catheter 101 makes use of a combination of optical and acoustic signal propagation for imaging capabilities.
Light reflected by blazed fiber Bragg grating 145 from photoacoustic transducer 135 and into fiber core 131 combines with light that is reflected by either fiber Bragg grating 149 or 141 (either or both may be including in various embodiments). The light from photoacoustic transducer 135 will interfere with light reflected by either fiber Bragg grating 149 or 141 and the light 137 returning to the control unit will exhibit an interference pattern. This interference pattern encodes the ultrasonic image captured by imaging device 135. The light 137 can be received into photodiodes within a control unit and the interference pattern thus converted into an analog electric signal. This signal can then be digitized using known digital acquisition technologies and processed, stored, or displayed as an image of the target treatment site. An incoming optical acoustical signal impinging on diodes creates an analog electrical signal which can be digitized according to known methods. Methods of digitizing an imaging signal are discussed in Smith, 1997, THE SCIENTIST AND ENGINEER'S GUIDE TO DIGITAL SIGNAL PROCESSING, California Technical Publishing (San Diego, Calif.), 626 pages; U.S. Pat. No. 8,052,605; U.S. Pat. No. 6,152,878; U.S. Pat. No. 6,152,877; U.S. Pat. No. 6,095,976; U.S. Pub. 2012/0130247; and U.S. Pub. 2010/0234736, the contents of each of which are incorporated by reference for all purposes.
In some embodiments, imaging fiber 129 operates to receive the incoming ultrasonic signal without necessarily being the source of the outgoing ultrasonic signal. An outgoing ultrasonic signal may be provided by a neighboring transducer 135, by another ultrasonic transducer such as a guidewire transducer, or by using balloon 107 itself as the source of ultrasonic energy. Angioplasty balloons as a source of ultrasonic excitation are discussed in U.S. Pat. No. 6,398,792 to O'Connor; U.S. Pat. No. 5,609,606 to O'Boyle. While using image detector 135 to view the target tissue, an operator can position balloon 107 in the appropriate place and inflate it.
The invention includes methods of providing an array of imaging fibers 129 that can be disposed around elongate shaft 111 as shown in
Detectors 135 can then be introduced by grinding a channel into the surface of all of the fibers. If done with the fibers un-cemented, the fibers can be rolled over and the grinding continued so that each fiber has an annular channel extending around the fiber. Fiber Bragg grating 149, 141, both, others, or a combination thereof can be formed, as well as any desired number of blazed fiber Bragg grating 145 in each fiber 129. A channel or cutaway can be formed for image detector and may optionally be filled with a photoacoustic transducer material. Suitable photoacoustic materials can be provided by polydimethylsiloxane (PDMS) materials such as PDMS materials that include carbon black or toluene. Imaging fibers and methods of making them are discussed in U.S. Pat. No. 8,059,923, the contents of which are incorporated by reference for all purposes. Once the sheet-like array is bound together (e.g., the adhesive has set), the sheet can be applied to a surface—for example, wrapped around catheter shaft 111.
Use of a catheter 101 of the invention allows for imaging from within a balloon and this may aid in properly delivering and positioning a stent 161.
References and citations to other documents, such as patents, patent applications, patent publications, journals, books, papers, web contents, have been made throughout this disclosure. All such documents are hereby incorporated herein by reference in their entirety for all purposes.
Various modifications of the invention and many further embodiments thereof, in addition to those shown and described herein, will become apparent to those skilled in the art from the full contents of this document, including references to the scientific and patent literature cited herein. The subject matter herein contains important information, exemplification and guidance that can be adapted to the practice of this invention in its various embodiments and equivalents thereof.
This application claims the benefit of, and priority to, U.S. Provisional Patent Application Ser. No. 61/740,479, filed Dec. 21, 2012, the contents of which are incorporated by reference.
Number | Date | Country | |
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61740479 | Dec 2012 | US |