Patent Publication Number: US-10314641-B2

Title: Anatomical thermal sensing device and method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 13/777,556, filed 26 Feb. 2013 (the &#39;556 application), which is a continuation of U.S. application Ser. No. 12/751,946, filed 31 Mar. 2010 (the &#39;946 application), now U.S. Pat. No. 8,388,549, which is a continuation-in-part of U.S. application Ser. No. 12/345,243, filed 29 Dec. 2008 (the &#39;243 application), now U.S. Pat. No. 8,317,810. The &#39;556 application, the &#39;946 application and the &#39;243 application are both hereby incorporated by reference as though fully set forth herein. 
    
    
     BACKGROUND OF THE INVENTION 
     a. Field of the Invention 
     The instant invention relates generally to anatomical devices and methods, including devices and methods useful for determining or locating relative positions within different parts of a varying anatomical structure (e.g., having different thermal capacity, tissue thickness, electrical or blood flow characteristics and the like). 
     b. Background Art 
     Practices are known for locating and gaining access to anatomical structures, including structures provided within a human body. For example, a current practice for gaining access to the left atrium is to manually puncture the intra-atrial septum at the location of the fossa ovalis. Because the location is difficult to find, and failure to puncture in a proper location can lead to significant complications, a physician may employ a combination of techniques to help verify that an appropriate site has been identified. Such techniques may include, inter alia, fluoroscopy, pressure monitoring, contrast injection, or various combinations of the foregoing. 
     Among other things, the teachings of the present disclosure provide a device and technique, whether employed alone or in combination with other techniques, to verify appropriate positions or locations within an anatomical body or structure. 
     BRIEF SUMMARY OF THE INVENTION 
     Medical devices that utilize temperature sensing to identify or assess anatomical bodies or structures are disclosed. Embodiments of the devices include an elongate tubular member, at least one electrode, a thermal sensor, and a temperature response assessment system or component. The elongate tubular member includes a distal portion having a distal tip and a side wall. The at least one electrode may be connected to the distal portion of the elongate tubular member, and the one or more electrode can be configured to provide energy to a portion of an anatomical body or structure. The thermal sensor may be configured to measure the thermal response of the portion of an anatomical body or structure, which may include, for example and without limitation, tissue or blood pools from the application and subsequent cessation or substantial cessation of sub-threshold energy. The temperature response assessment system or component can be operatively coupled to the thermal sensor. 
     In embodiments, the device may include a lumen and port opening, which may, for example, accommodate a tool, e.g., an access tool, such as a needle. Methods for using temperature sensing to identify an anatomical body or structure are also disclosed. 
     The foregoing and other aspects, features, details, utilities, and advantages of the present invention will be apparent from reading the following description and claims, and from reviewing the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a distal portion of a device in accordance with an embodiment; 
         FIG. 2  illustrates an embodiment of a device in contact with a relatively thicker portion of tissue. 
         FIG. 3  illustrates an embodiment of a device similar to that depicted in  FIG. 2 , depicted in contact with a relatively thin portion of tissue. 
         FIG. 4A  depicts a representative “heating” profile associated with the treated tissue portion illustrated in  FIG. 2 . 
         FIG. 4B  depicts a representative “heating” profile associated with the tissue portion illustrated in  FIG. 3 . 
         FIG. 5A  depicts a representative “heating-cooling” profile associated with the treated tissue portion illustrated in  FIG. 2 . 
         FIG. 5B  depicts a representative “heating-cooling” profile associated with the treated tissue portion illustrated in  FIG. 3 . 
         FIG. 6  illustrates a representative “heating” profile when the device is positioned in a blood pool. 
         FIG. 7  illustrates a representative “heating-cooling” profile when the device is positioned in a blood pool. 
         FIG. 8  illustrates an embodiment of a device including two ring electrodes and a lumen. 
         FIG. 9  illustrates the device of  FIG. 8  with a needle that extends through the lumen. 
         FIG. 10  illustrates an embodiment of a device including a side port opening provided between a first electrode and a second electrode. 
         FIG. 11  illustrates an embodiment of a device including a side port opening provided proximally of a first electrode and a second electrode. 
         FIG. 12  illustrates an embodiment of a device including an electrode ring that encircles or substantially circumscribes a side port opening. 
         FIG. 13  illustrates an embodiment of a device of the type shown in  FIG. 12 , including a segmented electrode ring that substantially encircles a side port opening 
         FIG. 14  illustrates an embodiment of a device similar to that shown in  FIG. 8 , the device including a lumen and a segmented electrode ring that substantially encircles the lumen. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A device  10  according to an embodiment is generally shown in  FIG. 1 . The device  10  includes an elongate tubular member  20  and a distal portion  30 . The distal portion  30  may include a thermal sensor or sensing mechanism that can be used for identifying or locating anatomical bodies or structures based upon relative thermal absorptive and dissipative properties of different portions of said bodies or structures. In embodiments, a device  10  may be configured to locate an anatomical landmark, such as portions of body tissue having such different characteristics. For example, in an application a device  10  may be employed to locate particular portions of a heart, including the fossa ovalis, relative to other portions of the heart. 
     With further reference to  FIG. 1 , the illustrated device  10  may include a first electrode  40  and a second electrode  50 . The first electrode  40  can be located at the distal tip  60  of the distal portion  30 , and the second electrode  50  may be provided spaced proximally of the first electrode  40 . The first electrode  40  may be a button-type, or a discrete unitary electrode and the second electrode  50  may be a ring electrode. For some embodiments the electrodes may, if desired, be comprised of nonconductive polymers doped or containing conductive material(s) such as flakes or particles of gold or the like, and thus may be MRI compatible. 
     The first electrode may include a thermal sensor  70 . In embodiments, the thermal (or temperature) sensor  70  may, for example, be a thermocouple, thermistor, an optical thermal sensor, or other type of temperature-monitoring sensor known in the art. The thermal sensor can be configured to, inter alia, provide feedback for the assessment of a thermal response gradient. In embodiments, the thermal sensor may be insulated or spaced from the electrode and may have a rapid time constant and high Q value. If the thermal sensor(s) is embedded in an electrode (the electrode serves as a heat transfer mechanism) a latency can be expected (and may be compensated for in an associated thermal response assessment). Moreover, for some embodiments, the sensor may, in addition to providing temperature sensing, may be configured to measure impedance. Also, as generally illustrated in  FIG. 1 , a segment or region  80  may be provided between a first electrode  40  and second electrode  50 . For some embodiments the segment or region  80  may provide a gap between the electrodes that is thermally conductive, but electrically insulative. The segment or region  80  may, for example and without limitation, comprise a non-conductive polymer. Moreover, in alternate embodiments, the thermal sensor  70  may be provided at other locations and may, for example, be located adjacent to the first electrode  40 . 
     In embodiments, at least one electrode may be configured to provide energy to a portion of an anatomical structure, e.g., a tissue portion, in a so-called unipolar or a bipolar configuration. Herein, a single electrode coupled to a portion of a medical device such as a catheter or introducer with a return path to another electrode not disposed on the device is deemed a unipolar configuration while a pair of spaced apart electrodes on the device is deemed bipolar. Thus the energy, which may be in the form of heat, may, without limitation, be applied by one or more electrodes employing unipolar or bipolar techniques, and the energy conveyed may, for example, be in the form of radio frequency (RF), microwave, laser, ultrasound, or closed-loop circulated heated fluids. It is noted that the energy or heat that is transferred by the device  10  may be in the form of a non-ablating amount or level of energy or heat that is delivered over a period of time. That is, embodiments of the disclosure may employ a “sub-threshold” energy such that the energy that is applied will not damage, ablate or otherwise promote necrosis or tend to perforate the tissue to which the energy is applied. 
     Without limitation, when first and second electrodes  40 ,  50  are provided, the electrodes may be configured to create a bi-pole along the distal portion  30  of the device  10 . When RF energy is delivered between the poles, an adjacent anatomical structure (e.g., adjacent tissue) will be heated. The thermal sensor  70  can be configured to measure the thermal response of the anatomical structure. 
     A controller  90 , which may include a temperature response assessment system or component, may be operatively coupled to the thermal sensor  70  and/or one or more electrodes associated with the device  10 . In embodiments, the temperature response assessment system or component may be integrated within a controller that may further be configured to control the energy or heat provided by one or more electrodes, whether the electrodes are separately controlled or controlled in combination. For example, without limitation, in  FIG. 1 , the controller  90  is generically shown linked by wires or conduits  92 ,  94  to the first and second electrodes  40 ,  50 , respectively. Further, as illustrated, a separate wire or conduit  96  may couple the controller  90  and thermal sensor. The controller may be configured to constrain the amount(s) or timing (and duration) of energy or heat provided by the device vis-à-vis one or more electrodes associated with the device. In embodiments, the controller may be configured to, inter alia: (a) constrain or “cap” the amount of the energy or heat provided by one or more electrodes—whether at any point in time and/or within a predetermined or specified period of time; (b) provide forms of temporal limitation(s) for the device, and the device may include a form of timing mechanism (e.g., a timer or clock) that assists with controlling the provision of energy or heat by the electrode or electrodes; (c) provide a specified range or profile of energy or heat that the device will be configured to observe; (d) include predetermined or specified not-to-exceed or “cut-off” temperature values (e.g., for tissue portions or anatomical structures) that may not be exceeded (i.e., the device will cease to supply (or reduce) heat or energy); (e) include algorithmic control(s) (such as permitting the picking of a set point temperature and measuring the time to reach the setpoint with limits based on time or energy delivered and/or a time rate-of-change metric for energy, temperature or other measurand); and include manual controls, Which without limitation, may permit manual setting of the amount(s) of heat or energy applied, the duration(s), or both the amount(s) and durations (e.g., in algorithmic profiles). 
     The disclosed concept recognizes and utilizes the finding that different anatomical structures or bodies can be assessed as exhibiting differing rates of temperature increase or decrease. By way of example, device  10  may be configured to locate anatomical structures, such as the fossa ovalis. More specifically, the inventors hereof have found that the interatrial septum exhibits a characteristic rate of temperature increase during application of energy and rate of temperature decrease (following cessation or substantial reduction of energy application) based on naturally occurring cooling effects associated with adjacent blood flow. That is, in the case of the interatrial septum, blood flow within the left atrium will have a greater impact on the thermal response in areas where the tissue is comparatively thin. Because the fossa ovalis is the thinnest portion of the septal wall, with the relevant blood flow, the fossa ovalis encounters notably different thermal effects, including heat transfer effects, compared to other portions of the interatrial septum. Thus, by monitoring the rates of temperature increase and/or decrease with respect to portions of the interatrial septum, embodiments of device  10  can permit a user to locate the fossa ovalis with a high degree of certainty. 
       FIGS. 2 and 3  provide a representative example of how a device  10  may be used to locate an appropriate site of puncture (e.g., the fossa ovalis) based on tissue thickness.  FIG. 2  illustrates device  10  in contact with a thick portion of tissue in the septum. The device  10  may be used to determine or observe a first thermal response—e.g., following cessation (or substantial reduction) of energy application associated with the thick portion of tissue. With regard to the notion of a substantial reduction in energy applied to tissue, the inventors suggest that without undue experimentation those of skill in the art will appreciate that it could be as little as one-half or less of a reduction for certain tissue substrates.  FIG. 3  illustrates the device  10  in contact with a relatively thin portion of tissue. The thermal response of the relatively thinner portion of tissue is relatively fast when compared with the first thermal response associated with the thicker portion of tissue. 
     It is noted that the thermal response of the relevant tissue may be observed in the form of a total (e.g., overall) temperature increase or decrease, a rate-of-change temperature increase or decrease, and/or a time-to-reach a preset temperature (e.g., time from a first measured temperature to a desired maximum or an intermediate temperature below a maximum or other preset temperature), as well as variations and combinations of the foregoing.  FIGS. 4A and 4B  generally illustrate thermal profiles during energy application.  FIG. 4A  depicts a representative “heating” profile associated with the treated tissue portion (i.e., the relatively thicker portion) illustrated in  FIG. 2 . Similarly,  FIG. 4B  depicts a heating profile associated with the treated tissue portion (i.e., the comparatively thinner portion) illustrated in  FIG. 3 . In the second profile—shown in  FIG. 4B —the tissue temperature rises more slowly and provides a measurable distinguishing characteristic for the comparative tissue portions. 
       FIGS. 5A and 5B  generally illustrate thermal response profiles—e.g., following a cessation of energy application.  FIG. 5A  depicts a representative “heating-cooling” response profile associated with the treated tissue portion (i.e., the relatively thicker portion) illustrated in  FIG. 2 . Similarly,  FIG. 5B  depicts a heating-cooling response profile associated with the treated tissue portion (i.e., the comparatively thinner portion) illustrated in  FIG. 3 . In the first response profile—shown in  FIG. 5A —the associated tissue is thicker and, therefore, cools comparatively more slowly than the response profile for a relatively thinner tissue portion—such as generally depicted in  FIG. 5B . 
     Embodiments of the devices may also be used to distinguish types or conditions of tissue that may or may not be of different thicknesses. For example, scar or treated tissue is known to generally exhibit different thermal characteristics than unscarred or untreated tissue. That is, their temperature response profiles differ and can be detected and distinguished. 
     Moreover, embodiments of the device may also be used to determine whether the distal end (e.g., distal tip) of the device is in contact with tissue.  FIG. 6  illustrates a representative “heating” profile (e.g., as depicted with  FIGS. 4A and 4   b ) when the distal tip is not in contact with tissue, but instead is in a blood pool. The profile may be relatively flat in nature. Similarly,  FIG. 7  illustrates a representative “heating-cooling” profile (e.g., as depicted with  FIGS. 5A and 5   b ) when the distal tip is not in contact with tissue, but instead is positioned in a blood pool. It is noted that at the point in time P, where cooling generally begins after energy application stops, a very fast decline in temperature may be observed. 
       FIG. 8  illustrates another embodiment of a device  10 ′ illustrating additional aspects of the disclosure. The illustrated device  10 ′ includes a first electrode  50   a  and a second electrode  50   b . In an embodiment, one or both of the first electrode  50   a  and the second electrode  50   b  may include a thermal sensor. The first and second electrodes  50   a  and  50   b —which may comprise ring electrodes—are located proximally of the distal tip of the device. The illustrated device  10 ′ further includes a lumen  110  provided within the tubular elongate tubular member  20 ′. The illustrated lumen  110  may include a lumen opening  112 , which in this embodiment is shown at the distal tip of the distal end  30 ′ of the device  10 ′. In embodiments, the lumen  110  may be a fluid and/or a needle lumen. It is noted that with irrigated embodiments, the thermal sensor may be disposed out of the direct flow of any associated irrigation fluid.  FIG. 9  depicts the device  10 ′ of  FIG. 8  with a tool, such as a needle  120  that extends through the lumen  110 , and may extend through the lumen opening  112 . The needle  120  may, for example, be a flexible non-conductive needle and/or may be used to puncture tissue, such as that associated with the intra-atrial septum. With embodiments of devices that include a lumen, it may be advantageous to provide an electrode (or a plurality of electrodes or electrode segments) in close proximity to the lumen opening. 
       FIG. 10  illustrates another embodiment of a device  10 ″ that includes a side port opening  130  in the elongate tubular member  20 ″. In the illustrated embodiment the side port opening  130  is provided between a first electrode  40 ″ and a second electrode  50 ″. The first electrode  40 ″ may include a thermal sensor, and the device  10 ″ additionally includes a lumen  110  provided within the tubular elongate tubular member  20 ″. As generally shown, a needle  120  may extend through the lumen  110  and can extend externally through the side port opening  130 .  FIG. 11  illustrates an embodiment of a device similar to that shown in  FIG. 10 ; however, a side port opening  130  is provided proximally of a first electrode  40 ″ and a second electrode  50 ″. 
     Further embodiments of devices  10 ″ that include side port openings  130  are shown in  FIGS. 12-14 .  FIG. 12  generally illustrates an electrode ring  140  that encircles or substantially circumscribes the side port opening  130 . As illustrated, the electrode ring  140  may be slightly offset, i.e., radially spaced from, the periphery of the side port opening  130 .  FIG. 13  illustrates an embodiment of a device  10 ″ similar to that shown in  FIG. 12 ; however, the electrode ring  140  is comprised of a plurality of spaced, segmented electrodes  160 . As generally shown in the illustrated embodiment, the segmented electrodes  160  may be configured to comprise a non-continuous ring that substantially encircles the associated side port opening  130 . Additionally, as generally illustrated in  FIGS. 12 and 13 , the device  10 ″ may optionally include a first/distal tip electrode  40 ″. The first, tip electrode  40 ″ is not limited to the form illustrated, and may be provided in other configurations. Further, if included, the first/distal tip electrode  40 ″ may be configured for bi-polar sensing and/or may include an integrated thermal sensor. 
       FIG. 14  illustrates an embodiment of a device  10 ″ similar to that shown in  FIG. 8  including a lumen  110  and a segmented electrode ring  50  that substantially encircles a distal tip port opening  170  (which may be similar to lumen opening  112 , previously described). The device  10 ″ shown in  FIG. 14  may also include thermal sensor provided in connection with the electrode ring  50  and which may be located at or about the distal tip port opening  170 . The segmented electrode ring  50  may include a plurality of spaced, segmented electrodes  160 , and may comprise a non-continuous ring. 
     Devices in accordance with embodiments of the disclosure may further be adapted for or used in connection with various navigation and/or visualization systems. That is, if desired for some applications, one or more systems may be employed to further confirm that a desired or specified anatomical landmark has been located by devices provided in accordance with teachings of the present disclosure, By way of example, and without limitation, such visualization systems may include fluoroscopic type systems; impedance-type systems (such as EnSite NAVX™ commercially available from St. Jude Medical, Inc.); magnetic visualization and position and orientation systems; MRI-based systems. It is noted that the electrode(s) employed by the device may be adapted to coordinate with one or more visualization systems. By way of example, without limitation, if a magnetic-type visualization system (e.g., gMPS commercialized by MediGuide, Ltd. or the CARTO system from Biosense Webster, Inc., a Johnson &amp; Johnson company) is intended to be used in connection with a device of the type associated with this disclosure, the device may be configured to include additional/necessary elements, such as magnets or coils. 
     Although numerous embodiments of this invention have been described above with a certain degree of particularity, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of this invention. All directional references (e.g., plus, minus, upper, lower, upward, downward, left, right, leftward, rightward, top, bottom, above, below, vertical, horizontal, clockwise, and counterclockwise) are only used for identification purposes to aid the reader&#39;s understanding of the present invention, and do not create limitations, particularly as to the position, orientation, or use of the invention. Joinder references (e.g., attached, coupled, connected, and the like) are to be construed broadly and may include intermediate members between a connection of elements and relative movement between elements. As such, joinder references do not necessarily infer that two elements are directly connected and in fixed relation to each other. It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not limiting. Changes in detail or structure may be made without departing from the spirit of the invention as defined in the appended claims.