Patent Application
20090204005
The invention is directed to devices for sensing movement within tissue at a target site to scan for the presence or absence of structures such as blood vessels so that a procedure may be performed at the target site in a safe manner.
When performing procedures through an endoscope, bronchoscope, or other such device there is a risk that the procedure might disrupt structures beneath a tissue surface (such as blood vessels), where the disruption then causes significant complications.
One such area is within the airways of the lungs where puncturing of a blood vessel beneath the airway surface can result in significant bleeding. In cases where a scope type device is used, the bleeding obstructs the ability of the medical practitioner to visualize the damaged area resulting in an escalation of complications. In some cases, a patient's chest must be opened to stem the bleeding.
Such risks occur in many types of scope-based procedures, including but not limited to lung based approaches. For example, creation of collateral channels in COPD patients poses such risks. For example see U.S. Pat. No. 6,692,494; U.S. patent application Ser. Nos. 09/947,144, 09/946,706, and 09/947,126 all filed on Sep. 4, 2001; U.S. Patent Application No. filed on Sep. 4, 2002: U.S. patent application Ser. No. 11/335,263, filed on Jan. 18, 2006; U.S. patent application Ser. No. 11/562,947, filed on Nov. 22, 2006; each of which is incorporated by reference herein in its entirety. In addition, biopsy procedures, and transbronchial aspiration procedures arc a few procedures that present the same risk of penetrating a blood vessel within the lungs.
The problem is further compounded when accounting for motion of the tissue. For example, because airway or other lung tissue moves due to tidal motion of the lungs (as a result of the mechanics of breathing), it is difficult to visually identify an area that was previously scanned unless the scanning device remains relatively stationary against the tissue. Moreover, the difficulty increases when considering that the procedure takes place through the camera of a bronchoscope or endoscope.
Aside from the risk to the patient, once the medical practitioner punctures a blood vessel, that practitioner is often understandably hesitant or risk averse when performing future procedures. As a result, while the benefit of these procedures is well known, the risks of complications may reduce the overall success of the procedure.
Additionally, during bronchoscope surgeries it is not uncommon for the interventionalist or surgeon to navigate the bronchoscope through 90 to 180 degree bends. For example, a bend of this nature may be required to reach an upper lobe of a lung in an airway bypass procedure as described in U.S. Pat. No. 6,692.494 and incorporated herein by reference in its entirety. Likewise, the catheter being advanced through the bronchoscope must also be able to bend to the same degree as the bronchoscope. The catheter must be able to bend and maintain its functionality. In the case of a catheter carrying an extendable needle, and being urged through a working channel of a bronchoscope, a number of challenges may arise including, for example, increased friction between the needle and the catheter's working lumen. The needle may engage or puncture the working lumen as it is advanced through a sharp turn. The needle may also damage the bronchoscope, or worse, injure the patient. In view of the above, a need remains to increase the operation and safety of catheter systems through turns of up to 180 degrees. Such a need remains in procedures that create channels to vent trapped gasses within the lungs, transbronchial aspiration procedures, transesophageal procedures, biopsy procedures, use of cytology brushes, etc. Furthermore, the need may arise in any lung based procedure or other procedures in other parts of the body.
The invention relates to devices and methods for sensing structures within tissue (such as blood vessels or other organs) while performing a procedure at the site.
The catheter member can be a tubular member. The catheter member can be a polymeric tube or a reinforced polymeric tube. As described herein, it may have one or more lumens to accommodate the variations of the devices within this disclosure.
The sensing assembly is used to scan the tissue to minimize causing undesirable injury to the patient. As discussed below, any number of sensing modes may be incorporated into the device. In one variation of the invention, a Doppler ultrasound transducer assembly is incorporated for sensing blood vessels within tissue.
In variations of the device, the sensing assembly is offset from an axis of the catheter assembly. The sensing assembly may also be positioned distal to the main catheter lumen. Doing so improves the ability of the sensing assembly to contact tissue surfaces when the device is advanced along body conduits. In addition, this offset and/or extension feature improves the ability to see the tip of the sensing assembly when the device is used with a scope type device.
The invention further includes methods of treating tissue, where the method includes selecting an area in the tissue for treatment, advancing the device into the lung to a tissue site, where the device includes a sensing assembly affixed to a catheter to sense for the presence or absence of blood vessels. The device may then allow for the use of a needle member comprising a curved needle that creates a passage. The device also includes various depth limiting features, such as a transition surface that causes tactile or sensory feedback to a physician if the device is advanced too far out the distal end of the sensing assembly, which can act as a stop. In addition, the needle assembly can include visual indicators to allow a physician to observe proper advancement of the needle.
As noted herein, one variation of the device permits scanning the tissue site by placing the sensing assembly in contact with the tissue site. However, various sensing assemblies may permit non-contact scanning. Regardless of whether the sensing tip contacts the tissue, creation of the opening or passage may be performed without significant movement of the scanning assembly. Such a benefit is apparent as medical practitioners may lose track of the scanned tissue if they are required to substitute or move the scanning assembly to create an opening.
The invention includes a medical device for sensing structures beneath tissue and penetrating tissue, the device comprising an elongate sheath having a near portion, a far portion, and a handle located on the near portion, the elongate sheath including at least one lumen extending through the handle to the far portion and exiting at a sheath opening, the elongate sheath being sufficiently flexible to navigate through a working lumen of a bronchoscope as well as a tortuous anatomy, a sensing element spaced distally from the sheath opening and positioned such that an active surface of the sensing element is able to scan in a distal direction to inspect tissue distal to a front tip of the elongate sheath while leaving the sheath opening proximally spaced from tissue, where the sensing element is coupleable to a sensing monitor, an elongate body member having a hub located at a proximal end, and a needle tip located at a distal end, the body member and needle tip being slidably located through the sheath lumen, where a length of the body member is greater than a length of the elongate sheath such that when the hub advances against the handle, the needle tip extends distally to the sensing element.
In another variation, the invention includes a medical device for sensing structures beneath tissue and penetrating tissue at a remote site in tortuous anatomy, the device comprising an elongate sheath having a near portion, a far portion, and a handle located on the near portion, the elongate sheath including at least one lumen extending through the handle to the far portion and exiting at a sheath opening, the elongate sheath having a reinforcing member extending at least partially therethrough and being sufficiently flexible and long to navigate through tortuous anatomy, a sensing element being coupleable to a sensing monitor, an elongate body member having a hub located at a proximal end, and a needle tip located at a distal end, the body member and needle tip being slidably located through the sheath lumen, where a length of the body member is greater than a length of the elongate sheath such that when the hub advances against the handle, the needle tip extends distally from the sheath opening, where the elongate body member has a column strength to allow the needle tip to puncture tissue when the hub advances against the handle, and where the needle tip comprises a curved tip and where a front portion of the curved tip curves towards a centerline of the needle tip thereby minimizing the front portion of the curved tip from interfering with an interior wall of the sheath lumen.
The invention also includes methods of creating an opening in tissue located in tortuous anatomy at a preferred site. In one variation the method includes advancing a device through the tortuous anatomy. The device includes a sensing element and a sheath where the sensing element extends distally beyond the sheath opening, scanning the tissue with the sensing element to identify the preferred site. The sensing element is pressed against the preferred site while keeping the sheath Opening spaced from the preferred site. The needle tip and elongate body member is extended from the sheath opening, where a transition section between the needle tip and the elongate body member comprises a reduced diameter section distal to an increased diameter section. In another variation, the elongate member comprises an increased diameter section. The needle tip pierces the tissue such that the transition section interferes with tissue causing sensory feedback at a proximal end of the elongate member. Elastic tissue will also constrict and conform to the reduced section such that continued advancement will result in an interference between the tissue and needle shaft.
As will be discussed below, a variation of the invention includes a Doppler ultrasound based sensing element 206 and control system 190. However, other modes are within the scope of this invention and regardless of the mode incorporated by the sensing assembly, the system 150 may include a user interface that allows the user to determine the presence or absence of a blood vessel at the target site. Typically, the user interface provides an audible confirmation signal. However, the confirmation signal may be manifested in a variety of ways (e.g., light, graphically via a monitor/computer, etc.)
Although depicted as being external to the device, it is contemplated that the control system 190 may alternatively be incorporated into the device 200. Moreover, the system 150 may incorporate any number of connectors or fittings that allow for either permanent or detachable connections of the fluid source, control system and/or any other auxiliary systems used with the system 150.
When using Doppler ultrasound to detect the presence of blood vessels within tissue, the ultrasound can operate at any frequency in the ultrasound range but preferably between 2 Mhz-30 Mhz. It is generally known that higher frequencies provide better resolution while lower frequencies offer better penetration of tissue. In one embodiment of the present invention, because location of blood vessels does not require actual imaging, there maybe a balance obtained between the need for resolution and for penetration of tissue. Accordingly, an intermediate frequency may be used (e.g., around 8 Mhz). In another embodiment of the invention, it is desirable to operate at a frequency of about 30 Mhz. A variation of the invention may include inserting a fluid or gel into the airway to provide a medium for the Doppler sensors to couple to the tissue to detect blood vessels. In those cases where fluid is not inserted, the device may use mucus found within the airway to directly couple the sensor to the wall of the airway.
As noted above, Doppler ultrasound was found to be an efficient way to identify blood vessels. As such, the control system 190 can be configured to communicate with an analyzing device or control unit adapted to recognize the reflected signal or measure the Doppler shift between the signals. The source signal may be reflected by changes in density between tissues. In such a case, the reflected signal will have the same frequency as the transmitted signal. When the source signal is reflected from blood moving within a vessel, the reflected signal has a different frequency than that of the source signal. This Doppler Effect permits determination of the presence or absence of a blood vessel within tissue. The Doppler system described herein comprises a Doppler ultrasound mode of detection. However, additional variations include transducer assemblies that allows for the observation of the Doppler Effect via light or sound as well.
Turning now to the device 200, the elongate sheath 202 typically has a sufficient length that allows a physician to advance the sheath 202 through tortuous anatomy to a remote site. As noted above, such a device is useful in the lungs, vasculature, or other such tortuous anatomy. Accordingly, variations of the sheath 202 are fabricated with sufficient flexibility and column strength to reach the intended target site. Although various sizes are within the scope of the invention, one configuration includes a sheath diameter of 1.8 mm with a 21 GA needle having a penetration depth of 10.9 mm. In one embodiment, the working length of the device can range from 1320 to 1473 mm.
As shown in
Although the variations discussed below include a needle assembly for the working device, the working device can include any number of devices. For example, the working device can include aspiration needles, transbronchial aspiration needles, biopsy devices, brushes, forceps, and other such devices that are able to be advanced through the lumen of the sheath 202 to the target site at the end of the device 200. In most variations, such medical appliances are of a small diameter. The use of the handle 208 provides a more convenient opening for insertion of a small device. For instance, attempting to insert an aspiration needle (e.g., 17-21 GA) into a small diameter lumen will be a lime consuming effort. Use of the hub 208 permits the medical practitioner to rapidly insert such a small sized appliance into the device 200.
Turning now to the sensing element 206, in the illustrated variation the sensing clement 206 is situated such that an active surface of the sensing element is able to scan in a distal direction to inspect tissue distal to a front tip of the elongate sheath. Such a configuration permits the sensing element 206 to scan the target site for structures beneath the tissue prior to insertion of the working device into the target site. Clearly, variations of the invention can include sensing elements that are angled or scan in a radial or an oblique direction relative to the sheath 202.
The sensing element can be any modality that is capable to scan beneath a surface of tissue. For exemplary purposes, the control system 190 and sensing element 206 are discussed herein as being a Doppler ultrasound system. As such, the sensing element 206 includes the sensing tip that is coupled to the power supply 190 as is known by those familiar with such systems. For example, the sensing element 206 may include any number of conducting members (e.g., wires) extending along the sheath 202 (either internally or externally to the sheath 202). In any case, these conducting members provide the energy and controls for the sensing element 206. In the case of Doppler ultrasound, the conducting members couple an ultrasound source 190 to the sensing element 206 where the element comprises an ultrasound transducer assembly or lens. The sensing clement 206 can be covered by a layer or coating to ensure biocompatibility and durability and an atraumatic tissue contact interface. The transducer or transducers may comprise a piezo-ceramic crystal (e.g., a Motorola PZT 3203 HD ceramic). In the current invention, a single-crystal piezo (SCP) is preferred, but the invention does not exclude the use of other types of ferroelectric material such as poly-crystalline ceramic piezos, polymer piezos, or polymer composites. The substrate, typically made from piezoelectric single crystals (SCP) or ceramics such as PZT, PLZT, PMN, PMN-PT; also, the crystal may be a multi layer composite of a ceramic piezoelectric material. Piezoelectric polymers such as PVDF may also be used. Micromachined transducers, such as those constructed on the surface of a silicon wafer are also contemplated. As described herein, the transducer or transducers used may be ceramic pieces coated with a conductive coating, such as gold. Other conductive coatings include sputtered metal., metals, or alloys, such as a member of the Platinum Group of the Periodic Table (Ru, Rh, Pd, Re, Os, Ir, and Pt) or gold. Titanium (Ti) is also especially suitable. The transducer may be further coated with a biocompatible layer such as Parylene or Parylene C.
Commonly assigned patent publication nos. US20020128647A1; US20020138074A1; US20030130657A1, and US20050107783A1; disclose additional variations of transducer assemblies and modes of securing such assemblies to the device. The entirety of each of which is incorporated by reference herein.
Moreover, variations of the inventive device include conducting members that comprise a series of wires, with one set of wires being coupled to respective poles of the transducer, and any number of additional sets of wires extending through the device. In addition, the sensing element 206 may have more than one sensing surface disposed along the portion of the sheath.
The degree to which the sensing clement 206 is offset and extends from the sheath 202 can vary depending on the particular application. For example, in certain variations, the sensing tip may be immediately distal to the far end of the sheath. In alternate variations, the sensing tip may extend as shown in the drawings. It may extend, for example, by 0.1 to 0.3 inches and more preferably about 0.20 to 0.25 inch. Such a construction is useful when the practitioner desires to view the sensing clement 206 at any orientation when the device extends from the endoscope.
Offsetting the sensing element 206 from the sheath opening can be accomplished any number of ways (as shown below). However, in the present variation, a wall 218 of the sheath 202 that defines the secondary lumen 214 extends beyond or distal to the sheath opening 216.
Various parameters and dimensions may be defined to characterize the needle tip 240 such as, but not limited to, the rigid length, outer diameter, inner diameter, bevel angle, and length of the bevel region as shown in
The tapered section 248 is smaller in diameter than an end of the elongate member 238. The joining of the two structures creates an irregular or discontinuous surface to provide the depth limiting feature. When used in tissue, as the needle tip 240 penetrates tissue, the curved tip 250 penetrates the tissue to conform to the outer diameter of the needle tip 240. The needle does not core or remove significant amounts of tissue. Once the needle 240 advances such that a portion of the tissue surrounds the transition section 244, the tissue recovers and conforms to the tapered section 248. Further advancement of the needle assembly 230 causes the tissue to engage the irregular or discontinuous transition to the distal end of the elongate member 238.
The needle 240 is joined to the elongate member 238 by, for example, a press fit, welding, an outer sleeve, heat shrinking tube, wrap, or an adhesive. The needle preferably has a relatively short length so that it may turn corners ranging from 90-180 degrees. In applications in the lung, for example, it is not uncommon to make a turn greater than 120 degrees. One application that requires the physician to navigate the instrument through a sharp turn is when it is necessary to access a site in the upper lobe of*the lung. The length of the needle 240 in this embodiment preferably ranges as indicated above.
In addition, or as an alternative to the needle configurations shown above, the sheath can be combined with various aspiration needles, transbronchial aspiration needles, biopsy devices, other such commonly known devices where removal of tissue or other fluids is desired.
In certain minimally invasive applications and interventional procedures (for example, bronchoscopically accessing the upper lobe of the lung) turns of 90 degrees or more are required. Navigating, extending and retracting a needle is a challenge. In such cases, the needle tip design described above, in combination with a puncture resistant working lumen, serves to prevent damage to the catheter, bronchoscope, and patient.
The sensing tip 206 of the device 200 should be in contact with the airway wall to function properly. A physician will confirm contact with the airway wall using bronchoscopic vision by the displacement of the airway wall with light forward pressure on the bronchoscope and/or device. In variations using a Doppler Ultrasound mode of detection, movement of the device against the airway wall can potentially cause sounds that may not be distinguishable from sounds of blood vessels. Accordingly, a physician may hold the device still, and listen for a period (e.g., 2-3 seconds) to confirm whether a vessel is the cause of the sounds. Stopping and listening for the period is also required in order to confirm the absence of vessels. In one technique, the physician sweeps the tip of the sheath 202 across the target site 114. The scanning can include circumferentially and axially scanning the areas surrounding the target site. The physician will frequently stop the device to listen for the sounds associated with vessels (i.e. if a blood vessel is present the user will hear a pulsing sound or a swishing sound indicating blood flow).
As shown in
As noted above, the needle 240 can advance into the target site without removing the sensing element 206 from the tissue. Accordingly, variations of the device require sufficient stiffness so that the tissue may be adequately probed without collapse of the sensing element 206 or segment carrying the clement. As described above, the system 150 provides the physician with audio or visual signals so that the physician can determine whether it is sufficiently safe to make an opening in the tissue. The physician may rotate, probe, circulate, traverse, or otherwise move the tip 206 in the area to reach a sufficient degree of confidence that the location or site is blood vessel free.
A further variation of the invention may include configuring the transducer assembly and/or controller to have different levels of sensitivity. For example, a first level of sensitivity may be used to scan the surface of tissue. Then, after creation of the opening, the second level of sensitivity may be triggered. Such a feature acknowledges that scanning of tissue on, for example, the airway wall may require a different sensitivity than when scanning tissue within the parenchyma of the lung.
It should be noted that the invention includes kits containing the inventive device with any one or more of the following components, a Doppler ultrasound controller, a conduit delivery catheter incorporating a conduit thereon, as described in one or more of the applications listed above, and a bronchoscope/endoscope.
In the above explanation of Figures similar numerals may represent similar features for the different variations of the invention.
The invention herein is described by examples and a desired way of practicing the invention is described. However, the invention as claimed herein is not limited to that specific description in any manner. Equivalence to the description as hereinafter claimed is considered to be within the scope of protection of this patent.
The devices of the present invention are configured to locate a target site for creation of a collateral channel in the tissue and to create an opening in tissue. As discussed above, a benefit of this combination feature is that a single device is able to select a target location and then create an opening without having been moved. Although the device is discussed as being primarily used in the lungs to create a collateral channel, the device is not limited as such and it is contemplated that the invention has utility in other areas as well, specifically in applications in which blood vessels or other structures must be avoided while cutting or removing tissue (one such example is tumor removal) or in Transbronchial Needle Aspiration or Transbronchial Needle Biopsy.
The above illustrations are examples of the invention described herein. It is contemplated that combinations of aspects of specific embodiments/variations or combinations of the specific embodiments/variations themselves are within the scope of this disclosure.
