Guidewire with centering mechanism

The invention provides a guidewire with a centering mechanism. The mechanism lifts the guidewire from a vessel wall and biases it towards the center of the vessel. Since the guidewire can be selectively lifted away from the vessel wall, scraping the catheter against the wall can be avoided, the tip can be guided into the correct branch of a bifurcation, and an imaging device can be used to its full potential. In certain aspects, the invention provides a guidewire with an elongated shaft with a proximal portion and a distal portion comprising a distal tip. One or more centering mechanism can be provided on a guidewire.

FIELD OF THE INVENTION

The invention generally relates to a guidewire for intravascular intervention, and particularly to mechanisms for centering a guidewire within a vessel.

BACKGROUND

Some people are at risk of having a heart attack or stroke due to fatty plaque buildups in their arteries that restrict the flow of blood or even break off and block the flow of blood completely. Angioplasty is a procedure for treating sites that are affected by plaque. In this procedure, a needle is used to make an opening through a patient's skin and into a blood vessel, often the femoral artery in the patient's leg. A sheath is used to hold the opening open and a radiopaque dye is injected, allowing physician view the treatment site on x-ray and select a suitable balloon catheter and a guidewire for treatment.

The guidewire is then inserted through the hole and guided through the artery until the tip just passes the treatment site. The physician guides the wire by twisting and manipulating the proximal end that sits outside the patient. With the wire in place, the balloon catheter is slid over the proximal end and pushed forward until the balloon lies within the narrowed area. The balloon is then inflated to compress the plaque or to deliver a stent.

A number of problems are associated with this procedure. For example, in places where the guidewire lies against the side of the vessel, pushing the catheter over the guidewire can scrape the catheter against the vessel wall. The guidewire tends to be pushed against the vessel wall by any curve in the vessel. Specifically, the guidewire will push against the inside wall at the peak of the curve and against the outside wall at the ends of the curve.

Curves also present navigational challenges. For example, where a curve in the vessel lies close to a branch-point, it can be difficult to guide the tip of the wire into the correct branch due to the strong tendency of the curve to push the wire towards one side of the vessel.

Some positioning difficulties could be helped by an imaging guidewire. For example, a guidewire with an ultrasound imaging tip could help a physician navigate the vessels. However, the tendency of the guidewire to push up against the vessel wall interferes with imaging. If the imaging device is pushed into the vessel wall, it will not be useful for viewing its environment.

SUMMARY

The invention provides a guidewire with a mechanism for centering the guidewire within a vessel. A physician can operate the mechanism to cause it to lift the guidewire from the vessel walls and bias it towards the center of the vessel. Since the guidewire can be selectively lifted away from the vessel wall, scraping the catheter against the wall can be avoided, the tip can be guided into the correct branch of a bifurcation, and an imaging device can be used to its full potential. Thus the centering mechanism improves visibility and helps maneuver the guidewire to the location where fatty plaque is narrowing the arteries. The centering mechanism also minimizes trauma to healthy tissue by keeping the catheter from scraping through the vessel walls. Since the centering mechanism helps navigate the balloon to the affected site while protecting healthy tissue, angioplasty procedures can reach a number of sites that otherwise may have been inaccessible due to complex combinations of curves and branch-points within the blood vessels. Thus, by pushing the tip away from vessel walls and helping the physician orient the guidewire in the intended direction of travel, while also improving the view offered by imaging guidewires, a guidewire centering mechanism can be valuable for treating a person who is at serious risk for heart attack or stroke.

In certain aspects, the invention provides a guidewire for an intravascular procedure. The guidewire has an elongated shaft with a proximal portion and a distal portion comprising a distal tip. A centering mechanism is provided on the distal portion so that, when the distal portion is inserted into a vessel in a body, the centering mechanism can be operated to center the guidewire in the vessel. A guidewire can include a single centering mechanism, or a number of centering mechanisms disposed at different locations along the length.

In some embodiments, the centering mechanism uses a flexible sleeve that bows outward from an axis of the guidewire when compressed in a direction parallel to the axis. The flexible portion of the sleeve can be compressed by translating an outer sleeve along an inner core. For example, the proximal portion of the guidewire can present, to a physician, a graspable portion of the outer sleeve and of the inner core, allowing the physician to pull back the outer sleeve causing the centering mechanism to bow outwards. Moreover, the guidewire can be designed to transmit torque so that a physician can twist the proximal portion to cause the distal, inserted portion to twist. For example, torque can be transmitted by a key and keyway structure or a splined structure.

In certain embodiments, the centering mechanism includes a balloon. A balloon can be included that surrounds the guidewire and inflates into a torus. Or, a balloon can be included that inflates into a spheroid lobe on one side of the guidewire. Where a centering mechanism comprises one or a number (e.g., three) lobe-shaped balloons, one, selected ones, or all of the balloons can be inflated to center the guidewire without occluding the flow of blood. Other embodiments of a centering mechanism can be provided that do not occlude the flow of blood. For example, a centering mechanism can make use of one or more struts configured to expand out from the guidewire to push the wire away from the vessel wall. A sleeve or band can be included to constrain the strut or struts against a core member. Removing the sleeve from the vicinity of the strut results in the strut expanding away from the core member. Moreover, the centering mechanism can be configured so that the sleeve can be returned to its original position to compress the strut back against the core member.

A guidewire of the invention can include a centering mechanism along with other features. For example, a guidewire can include an imaging device. In some embodiments, an acoustic transducer is included for intravascular ultrasound imaging. The guidewire can be an IVUS imaging guidewire or can include an optoacoustic imaging fiber. An optoacoustic imaging fiber can use a photoacoustic transducer on an optical fiber that include one or more fiber Bragg grating to send an optical signal along the length of the fiber and guidewire while using an acoustical signal to image the tissue. The acoustic signal is received through the photoacoustic transducer and the signal information is carried out through the proximal end of the guidewire by the optical signal (e.g., as an interferometric signal).

In related aspects, the invention provides a coronary intervention system that uses a catheter with a treatment device and a guidewire that includes a centering mechanism. The guidewire is configured to be inserted into a blood vessel and the catheter is configured to slide over the guidewire to carry the treatment device to a treatment site. The catheter may itself include a structure for centering the guidewire in the vessel. This way, the guidewire may be centered by both the guidewire centering mechanism and the catheter structure, thus allowing the guidewire to be centered in more than once place, or giving a physician greater control of guidewire navigation. The guidewire centering mechanism can operate through the use of a balloon, one or more struts, or a pliable material configured to bow outwards from the guidewire. In certain embodiments, the guidewire has a central core member and an outer sleeve member that can be translated relative to the core member in a direction substantially parallel to an axis of the guidewire.

Aspects of the invention provide methods of performing angioplasty that include inserting a guidewire into a vessel of a patient and operating a centering mechanism disposed at a distal portion of the guidewire to bias the distal portion towards the center of the vessel. A catheter can be introduced to the treatment site by using the guidewire. These steps can be performed in any order. The guidewire centering mechanism can be employed when the catheter is already substantially advanced over the guidewire or the centering mechanism can be used when only the guidewire is substantially within the vessel, to aid in navigating the guidewire into position.

DETAILED DESCRIPTION

Embodiments of the invention provide a guidewire with an expandable element that biases the guidewire to a particular location within a vessel, facilitating the precise placement of the guidewire and providing greater accuracy during subsequent catheter procedures. The expandable element can function as a centering mechanism, tending to center the guidewire within the vessel. A guidewire of the invention may also include detection elements that detect placement of the guidewire and subsequent therapy.

FIG. 1shows a catheter101according to certain embodiments of the invention. Catheter101includes a proximal portion103that is generally outside of a patient during use and a distal portion105extending to a distal tip109configured for insertion into a patient. Distal portion105may generally include a treatment device. Guidewire201may be seen extending from distal tip109. Pictured inFIG. 1is a stent disposed around a balloon, but any suitable treatment device may be included. A length of catheter101extending through distal portion105generally defines a catheter shaft111capable of being delivered over guidewire201. Intravascular balloon catheters are used for such procedures as balloon angioplasty, or percutaneous transluminal coronary angioplasty (PTCA). Catheter101generally includes a pliable material that provides flexibility or maneuverability, allowing catheter101to be guided to a treatment site in a patient's blood vessels. Preferably, catheter101has enough stiffness to allow it to be pushed to a target treatment site, and accordingly, an ability to optimize a balance of pliability versus stiffness or pushability is beneficial to medical use. Elongate shaft111may 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). Generally, shaft111will be capable of transmitting torque along an axis of the shaft. Catheter101may itself include a mechanism to aid in centering. For example, U.S. Pat. No. 7,547,304 to Johnson described a guidewire centering catheter tip. U.S. Pat. No. 5,660,180 to Malinowski describes an intravascular ultrasound imaging guidewire that can be centered through use of a catheter.

Catheter101may include an angioplasty balloon or other interventional device at distal portion105to 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, catheter shaft111will include a guidewire lumen so that the catheter may be advanced along guidewire201. A guidewire lumen in a balloon catheter is described in U.S. Pat. No. 6,022,319. 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. Other suitable materials for use in catheter101include high density polyethylene (HDPE) or combinations of material, for example, bonded in multiple layers.

Catheter101may include coaxial tubes defining separate inflation and guidewire lumens, for example, along a portion of, or an entirety of, a length of catheter101. A plurality of lumens may be provided in parallel configuration or coaxial at one point and parallel at another, with a transition such as a plunging portion that traverses a wall located between the parallel and the coaxial portions (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. Catheter101is generally introduced into vessel and advanced to a site of treatment by the use of guidewire201.

FIG. 2depicts guidewire201. Guidewire201generally has a proximal portion213and a distal portion209terminating at distal tip205. Guidewire201includes a mechanism to bias a location of guidewire201away from a vessel wall when guidewire201is inserted therein. Guidewires are discussed in U.S. Pat. Nos. 5,439,139 ;3,789,841; 6,059,738; and 6,423,012

FIG. 3shows a centering mechanism215according to certain embodiments of the invention. Here, mechanism215includes a pliable polymer sheath219fixed to a core member221near a distal tip205of guidewire201. The other end of sheath219is fixed to a sleeve member217disposed around core member221. Sleeve member217is configured to translate longitudinally relative to core member221, in a direction substantially parallel to an axis of guidewire201.

FIG. 4shows the centering mechanism215ofFIG. 3in an expanded configuration. When sleeve member217is translated in a direction towards distal tip205, relative to core member221, polymer sheath219bows outward from guidewire201. Preferably, sheath219includes a polymer with elasticity, such as a urethane or PTFE polymer. An operator can center guidewire201by pushing sleeve217inwards towards a patient away from a proximal end of guidewire201. If sheath219includes enough elasticity, it will tend to return to a non-expanded state of its own disposition. Sheath219can be substantially contiguous so that in its expanded state it tends to occlude blood flow. In other embodiments, sheath219can include slits parallel to an axis of guidewire201so that when it expands, separate strips of the polymer bow outwards and allow blood to flow past centering mechanism215even while deployed.

FIG. 5shows centering mechanism215being deployed to center distal portion209of guidewire201near a treatment site151. Here, distal tip109of catheter101is shown being used to introduce balloon107. As can be seen inFIG. 5, distal tip109is kept away from the vessel walls to prevent damage to the tissue. An expandable pliable sheath is thus one mechanism for a centering mechanism. Other embodiments are provided.

FIGS. 6 and 7illustrate use of an inflatable balloon225at a distal portion209of guidewire201as a centering mechanism. Guidewire201includes balloon inflation lumen227(shown here disposed within guidewire201—lumen227could also be provided as a tube along a side of guidewire201). Forcing an inflation fluid (e.g., air, gas, water, saline, etc.) through inflation lumen inflates the balloon as shown inFIG. 7.FIG. 19illustrates a guidewire201being centered within a vessel151with a plurality of balloons26a,26b,26cas a centering mechanism.

FIG. 8shows use of balloon225as centering mechanism215to center guidewire201in a site within a vessel151. Distal tip of a catheter109is again illustrated to show that it is kept away from the vessel wall by centering mechanism215.

FIG. 9shows a strut-based embodiment of a centering mechanism215of the invention. Here, guidewire201includes a central core221surrounded by outer sleeve217. Outer sleeve217compresses one or more of strut235against the side of core221. Strut235can include a springy material or a shape-memory material (e.g., steel, iron, nitinol, etc.) that tends to bias strut235away from core221. Sleeve217can include one or more aperture237. When sleeve217is translated relative to core221, aperture237is positioned over strut235. Strut235is then released and expands away from core221under its own dispositional bias.

FIGS. 11 and 12give perspective views of a centering mechanism215including a plurality of struts235in the compressed and expanded states, respectively. While shown here using a sleeve217with aperture237, sleeve217could also operate to compress one or more of strut235, and to allow them to expand, by having a terminal edge disposed in a vicinity of the strut or struts. Pull back on sleeve217can cause a terminal end of sleeve217to be removed from strut or struts235, allowing them to expand. Sleeve217could then be pushed forward to compress strut or struts235. Other arrangements are also possible and within the scope of the invention. For example, a terminus of sleeve217may have a straight (circular) edge, or may have a scalloped or slotted appearance, with individual recess for individual ones of strut235.

FIG. 13is a cross-sectional view of a centering mechanism215including a plurality of struts235taken along the dotted line shown inFIG. 10. While shown inFIG. 13as including three of strut235, centering mechanism215can include any number of strut235. In fact, in certain embodiments, a single one of strut235provides a mechanism for biasing guidewire201away from a vessel wall in one direction.

FIG. 14shows a cross sectional view of a single strut235for biasing guidewire201away from a vessel wall. Strut235as depicted inFIG. 14may be operated substantially as described above with regards toFIGS. 9 and 10. Biasing a guidewire201away from a vessel wall may be particularly beneficial for a guidewire that is configured to transmit torque from one end to another. For example, an operator may view guidewire201via x-ray angiography and see that it needs to be pushed away from a vessel wall. The operator may twist the proximal end until the single strut235appears on the angiograph as oriented towards the wall. The operator may then deploy centering mechanism215to bias guidewire201towards a center of the vessel. Accordingly, embodiment of the invention that include a sheath surrounding a core can optionally include a structure for transmitting torque from one portion of guidewire201to another. Any suitable torque transmitting mechanism may be employed. In certain embodiments, torque is transmitted by a key and keyslot mechanism or by a spline mechanism.

As shown inFIG. 14, sleeve217includes bosses241defining a keyslot and core221includes a key245that fits therein. One of skill in the art will recognize that variations are possible such as placing one or more key or keyslot on either of core221and sleeve217. Additionally or alternatively a surface of core221, sleeve217, or both can be splined.

FIG. 15shows a centering mechanism215for a guidewire201that includes five of strut235. The centering mechanism215is depicted from the proximal perspective with each of strut235mounted to core221at a proximal end of strut235. Thus a mounted, butt-end of each strut235is seen, with a elongated member of each strut extending away from the view, into the page, and biased away from core221.

Struts235can be assembled on guidewire by any suitable means including, for example, welding, co-molding, clamping, banding, or adhesives. In some embodiments, a portion of strut235is swaged into the material of core221. A band (e.g., metal or a polymer) may also be strapped around the bases of struts235. Adhesives or spot welds may be additionally used, as desired. Thus a guidewire201of the invention includes a mechanism215for centering the guidewire within a vessel.

FIG. 16shows a cross-sectional view through distal portion105of catheter101. Running through catheter101is catheter shaft111defining guidewire lumen117extending to distal tip109. Inflation channel119may generally be disposed along guidewire lumen117along a length of catheter shaft111. Balloon107surrounds inflation lumen113which is in fluid communication with inflation channel119. Guidewire201may optionally include one or more of imaging device135. Balloon107may be any suitable balloon known in the art such as, for example, an angioplasty balloon. Balloon107is configured to be expandable, and may be used to deliver stent161or to open an obstructed vessel. Balloon107generally includes a strong flexible material and exhibits a narrow profile in an un-inflated state. Any suitable material may be used for balloon107including, for example, polyolefins such as polyethylene, polyvinyl chloride, polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) and copolyesters, polyether-polyester block copolymers, polyamides, polyurethane, poly(ether-block-amide) and the like. Balloons are described in U.S. Pat. No. 7,004,963; U.S. Pub. 2012/0071823; and U.S. Pub. 2008/0124495, the contents of each of which are incorporated by reference. Materials for balloon catheters are described in U.S. Pat. No. 5,820,594. Balloon catheters are described in U.S. Pat. Nos. 5,779,731 and 5,411,016.

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. Nos. 7,951,186; 7,777,399; and U.S. Pub. 2007/0247033, the contents of each of which are incorporated by reference.

In some embodiments, guidewire201includes imaging fiber129extending from a proximal portion103of catheter101. At proximal portion103, imaging fiber129may be operably coupled to a control unit (not pictured) via an optical coupler. Imaging device135may include any suitable imaging technology known in the art. In certain embodiments, device101uses optical-acoustic transduction to perform ultrasound imaging using imaging fiber129and imaging device135.

FIG. 17shows an imaging fiber129configured for optical-acoustic imaging. Along fiber129, a cladding surrounds fiber core131. Light137is transmitted from the control unit down a length of fiber129. Within fiber core, fiber Bragg grating149partially reflects light137. Also, where included, terminal fiber Bragg grating141reflects light. Additionally, blazed fiber Bragg grating145reflects light in a direction substantially radial to an axis of fiber129. The radial portion of the path of light137extends to photoacoustic transducer135. When light137impinges on photoacoustic transducer135, phonons are generated, leading to thermal strain of photoacoustic transducer135. Thus, photoacoustic transducer135uses incoming light137as an energy source to generate a longitudinal pressure wave139. When distal portion105is in a patient's vessel, pressure wave139can be used for ultrasonic imaging of material in the vessel, plaque, the vessel wall, surrounding tissue, other material, or a combination thereof. Parts of wave139that bounce back constitute the return signal that will contribute to the ultrasonic image data. 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.

In some embodiments, this return signal impinges on photoacoustic transducer135. The energy of return signal causes a vibration or deformation of photoacoustic transducer135. This results in a change in length of light path137. In some embodiments, the primary change in length of light path137is in the radial portion extending between photoacoustic transducer135and fiber core131, substantially perpendicular to an axis of fiber129. However, deformations in geometry of cladding133may result in a change of length of light path137in, for example, the region between fiber Bragg grating149and blazed fiber Bragg grating145. Depending on a desired embodiment, one may be favored over the other by cladding a portion of fiber129in a material with different rigidity or changing proportions of the depicted elements. Light reflected by blazed fiber Bragg grating from photoacoustic transducer135and into fiber core131combines with light that is reflected by either fiber Bragg grating149or141(either or both may be including in various embodiments). The light from photoacoustic transducer135will interfere with light reflected by either fiber Bragg grating149or141and the light137returning to the control unit will exhibit an interference pattern. This interference pattern encodes the ultrasonic image captured by imaging device135. The light137can 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, THESCIENTIST ANDENGINEER'SGUIDE TODIGITALSIGNALPROCESSING, California Technical Publishing (San Diego, Calif.), 626 pages; U.S. Pat. Nos. 8,052,605; 6,152,878; 6,152,877; 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 related embodiments, imaging fiber129operates without a blazed fiber Bragg grating and detects a change in path length between fiber Bragg gratings149and141associated by a strain induced on fiber129by the impinging sonic return signal. In some embodiments, separate imaging fibers129are used to send and to receive an ultrasonic image. Methods of optic-acoustic imaging using fiber Bragg gratings for use with the invention are discussed in U.S. Pat. No. 8,059,923 and U.S. Pub. 2008/0119739, the contents of which are incorporated by reference in their entirety.

The invention includes methods of providing an array of imaging fibers129that can be disposed around guidewire201and further provides methods of creating a plurality of image detectors135that are all oriented in a desired direction. In some embodiments, a plurality of substantially featureless optical fibers are arrayed in a sheet substantially parallel to one another. The sheet of fibers may be positioned on a sheet of material that may optionally have an adhesive on the surface. Additionally or alternatively, a cementing material may be applied to the sheet-like array of fibers. The fibers129may be arrayed in substantially straight lines (e.g., by combing prior to application of adhesive or cement) or may be in other conformations. For example, introducing a wavy or zigzag pattern into a portion of the fibers129may give them slack, or “play”, that allows image detectors to stay in place as guidewire201bends or twists. Once the fibers are so arrayed and held in place, the fiber Bragg gratings may then be formed in all of them. The fiber Bragg gratings may be formed by an inscribing method using a UV laser and may be positioned through the use of interference or masking. Inscribing and use of fiber Bragg gratings are discussed in Kashyap, 1999, FIBERBRAGGGRATINGS, Academic Press (San Diego, Calif.) 458 pages; Othonos, 1999, FIBERBRAGGGRATINGS: FUNDAMENTALS ANDAPPLICATIONS INTELECOMMUNICATIONS ANDSENSING, Artech (Norwood, Mass.) 433 pages; U.S. Pat. Nos. 8,301,000; 7,952,719; 7,660,492; 7,171,078; 6,832,024; 6,701,044; U.S. Pub. 2012/0238869; and U.S. Pub. 2002/0069676, the contents of each of which are incorporated by reference.

Detectors135can 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 grating149,141, both, others, or a combination thereof can be formed, as well as any desired number of blazed fiber Bragg grating145in each fiber129(seeFIG. 17). 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 shaft111.

Other imaging modalities may be included in system101. Imaging device135can 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, catheter101may include an ultrasound transducer as imaging device135. 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 A1; 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, catheter101makes use of a combination of optical and acoustic signal propagation for imaging capabilities.

FIG. 18illustrates a guidewire201with centering mechanism215being introduced into a treatment site151of a vessel so that catheter body111can be used to deliver balloon107to the treatment site. As shown inFIG. 18, as catheter101approaches treatment site151(such as a region of a blood vessel affected by atherosclerotic plaque), a physician can view site151on a monitor of an associated medical imaging instrument (not pictured). Using, for example, IVUS or optical-acoustic imaging, the vessel wall is viewed to monitor for the location of atherosclerotic plaques. Monitoring a position of catheter111may also be optionally combined with use of standard x-ray angiographic techniques. When balloon107is positioned at the target treatment site, it is inflated to open a passageway that will allow blood to flow past the stenosized (narrowed) portion of the vessel after the balloon is deflated. Balloon107may also be optionally used to deploy a stent. Such vascular intervention procedures by catheter are often performed in specialized clinical environments known as cath labs. Cath labs and associated imaging instrumentation (e.g., IVUS and OCT instruments) are known in the art. For example, IVUS is discussed in U.S. Pat. Nos. 8,289,284; 7,773,792; U.S. Pub. 2012/0271170; U.S. Pub. 2012/0265077; U.S. Pub. 2012/0226153; and U.S. Pub. 2012/0220865. Optical-acoustic imaging structures (e.g., for imaging fiber129) are discussed in U.S. Pat. Nos. 8,059,923; 7,660,492; 7,527,594; 6,261,246; 5,997,523; U.S. Pub. 2012/0271170 and U.S. Pub. 2008/0119739. The contents of each of these patents and publications are incorporated by reference in their entirety for all of their teachings and for all purposes. As shown inFIG. 8, use of a centering mechanism215allows for centering of guidewire201in the vessel, thus preventing balloon107or another portion of catheter101from scraping the vessel wall.

INCORPORATION BY REFERENCE

EQUIVALENTS