Abstract:
A system comprises a first signal handling unit sized and shaped for insertion to a reference distance within a first body cavity and a probe sized and shaped for insertion into a second body cavity the probe including an energy emitting head and a second signal handling unit, wherein one of the first and second signal handling units comprises a transmitter and the other of the first and second signal handling units comprises one of a receiver adapted to receive signals from the transmitter and a signal reflecting element, wherein, when the other of the first and second signal handling units comprises a signal reflecting element, the one of the first and second signal handling units comprises a receiver in combination with a controller operatively connected to the receiver, the controller generating an output varying as a distance between the first and second signal handling units varies. In addition, a system comprises a probe sized and shaped for insertion in a first body cavity and a measuring element extending from the probe to contact tissue adjacent to an opening to a second body cavity, the measuring element being movably coupled to the probe to vary a depth to which the probe may be inserted into the first body cavity before the measuring element contacts the tissue adjacent to the opening of the second body cavity.

Description:
PRIORITY CLAIM  
       [0001]     The present invention claims the benefit of U.S. Provisional Patent Application No. 60/667,968 entitled “Device and Method for Positioning a Therapeutic Device” filed Apr. 4, 2005, the entire disclosure of which is expressly incorporated herein by reference. 
     
    
     FIELD OF INVENTION  
       [0002]     The present invention generally relates to medical apparatus and treatment methods. Specifically, the present invention relates to methods and devices to accurately position medical implements in the human body. More particularly, the present invention describes an apparatus and method to treat urinary incontinence and, more particularly, stress incontinence with a vaginal probe.  
       BACKGROUND  
       [0003]     Stress urinary incontinence (SUI) occurs when tissue supporting the pelvic floor no longer provides sufficient support to the bladder neck and urethra, particularly the proximal urethra. Because of this condition, the bladder pushes against the urethra. Pressure from the abdominal muscles (e.g. during such activities as laughing, sneezing, coughing, exercising or straining to lift objects) can then cause undesired urine emissions. Females whose pelvic floors have stretched due to, for example, childbirth, obesity, etc. are more likely to suffer from stress incontinence.  
         [0004]     Several treatments for SUI are available, ranging from medications to surgical interventions. One minimally invasive treatment for SUI utilizes radio frequency (RF) energy delivered to tissue of the pelvic floor, specifically to the endopelvic fascia (EPF) which lies beneath the surface of the vaginal wall. The RF energy heats the tissue of the endopelvic fascia and causes the collagen in the tissue to denature, so that the fascia shrinks. When the fascia shrinks, it returns the bladder and urethra to a more natural position within the pelvis, reducing the symptoms of incontinence. Other types of energy may be used to heat the tissue, such as acoustic energy, laser energy, microwaves etc.  
         [0005]     Procedures to treat the endopelvic fascia require the accurate placement of the energy source within the vaginal canal of the patient, to successfully heat the target tissue. More generally, there are many medical procedures where a probe or other ‘medical implement is inserted into a body lumen or cavity, to achieve some therapeutic effect on the surrounding tissue. In all these procedures, it is important to be able to accurately place the probe or other device relative to the target tissue, without direct visualization of the device. This task may be made difficult because of the geometry of the lumen, or because of the lack of convenient reference points near the opening of the lumen.  
       SUMMARY OF THE INVENTION  
       [0006]     In one aspect, the present invention is directed to a system comprising a first signal handling unit sized and shaped for insertion to a reference distance within a first body cavity and a probe sized and shaped for insertion into a second body cavity the probe including an energy emitting head and a second signal handling unit, wherein one of the first and second signal handling units comprises a transmitter and the other of the first end second signal handling units comprises one of a receiver adapted to receive signals from the transmitter and a signal reflecting element, wherein, when the other of the first and second signal handling units comprises a signal reflecting element, the one of the first and second signal handling units comprises a receiver in combination with a controller operatively connected to the receiver, the controller generating an output varying as a distance between the first and second signal handling units varies.  
         [0007]     According to a further aspect, the present invention is directed to a system comprising a probe sized and shaped for insertion in a first body cavity and a measuring element extending from the probe to contact tissue adjacent to an opening to a second body cavity, the measuring element being movably coupled to the probe to vary a depth to which the probe may be inserted into the first body cavity before the measuring element contacts the tissue adjacent to the opening of the second body cavity. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0008]      FIG. 1  is a cross-sectional diagram showing the anatomy of the female urinary and reproductive systems;  
         [0009]      FIG. 2  is a schematic diagram showing an energy delivery device with a position sensing system according to a first embodiment of the present invention, in a desired position within the vaginal canal;  
         [0010]      FIG. 3  is a diagram showing an energy delivery device with a position sensing system according to a second embodiment of the present invention;  
         [0011]      FIG. 4  shows a perspective view of the device shown in  FIG. 3 , in a desired position within the vaginal canal; and  
         [0012]      FIG. 5  illustrates the method for measuring a depth of insertion of the probe within the vaginal canal corresponding to a desired location along the urethra. 
     
    
     DETAILED DESCRIPTION  
       [0013]     The present invention may be further understood with reference to the following description and the appended drawings, wherein like elements are referred to with the same reference numerals. The present invention is related to medical devices used to treat tissue adjacent to the walls of a body lumen or cavity, and to determine the position of the devices within the lumen. More specifically, the invention relates to a system for determining the position, relative to the urethra, of a device inserted into the vaginal canal for treatment of the endopelvic fascia.  
         [0014]     Many medical procedures rely on inserting a medical implement into a body cavity or lumen of a patient, to carry out some therapeutic activity. For example, energy may be delivered from a probe into tissue surrounding the body cavity or lumen, to heat the tissue, to ablate portions of target tissue, or for other purposes. Energy may be delivered in the form of radio frequency energy, microwave energy, laser light, acoustic energy or any other appropriate form of energy. The location of the energy delivery probe within the lumen, in most cases, needs to be known so that the energy is delivered to the correct location to achieve te desired result. Direct visualization of the device, for example using fluoroscopy, may be used, however a simpler and less expensive way of determining the location of the device is often desirable.  
         [0015]     One exemplary condition that can be alleviated by targeted delivery of energy is stress urinary incontinence (SUI). The treatment of SUI by altering the properties of the endopelvic fascia adjacent to the anterior vaginal wall and to the urethra is enhanced when the location on the endopelvic fascia of the tissue to be treated is precisely determined, and when treatment is accurately delivered to this location. However, difficulties in accurately treating a desired location may arise when the device for treating this tissue is inserted into the vaginal canal to a location determined with reference to a point along the urethra. This is often the case in treating SUI, because the location of the endopelvic fascia is typically determined along the urethra, but the therapeutic probe is inserted in the vagina.  
         [0016]     For example, to ensure the safety and efficacy of procedures which treat the fascia by heating and shrinking it (e.g., through application of RF or ultrasound energy), accurately locating the device to deliver energy to the target tissue is important. For example, in these procedures, a location halfway between the urethral opening and the bladder neck may be chosen. This distance may be measured accurately by, for example, inserting a Foley catheter into the urethra to the bladder neck. However, difficulties arise when attempting to position a device within the vaginal canal adjacent to this accurately determined position. Specifically, although the vaginal canal is usually substantially parallel to the urethra, inserting a device into the vaginal canal to the measured distance determined from the urethra will not result in an accurate positioning of the device, as the opening to the vaginal canal  12  and the opening to the urethra  14  are in different planes as shown in  FIG. 1 . The amount of separation A between the two differs from patient to patient. In addition, as the opening to the vaginal canal  12  is not well defined, it is difficult to account for this separation A when positioning the device.  
         [0017]     According to exemplary embodiments of the invention, a system is provided to determine the exact position of a medical probe within a body lumen or cavity, to place said probe at a predetermined location that maximizes the effectiveness of the treatment. The position sensing system allows the user, for example the physician performing the procedure, to place the probe in the desired location without using a direct visualization method such as fluoroscopy or an invasive surgical procedure. Instead, location of the probe is determined with reference to a nearby anatomical feature that is easier to determine than is location based on features of the lumen in which the probe is inserted.  
         [0018]     In one exemplary embodiment, the probe comprises an ultrasound source that is used to treat SUI. During treatment, the probe is inserted into the vagina of the patient, and acoustic energy is generated and focused on the endopelvic fascia located beyond the wall of the vagina. The focused acoustic energy causes the fascia to contract, as described above, and brings about a reduction of the symptoms of incontinence. According to the invention, a transmitter and receiver pair is used to accurately and remotely locate the probe inside of the patient, and to specify the correct position where the probe should be placed to successfully carry out the procedure.  
         [0019]     The ultrasound probe may be constructed, for example, as described in U.S. patent application Ser. No. 11/092,463, filed Mar. 29, 2005, entitled “Apparatus and Method for Stiffening Tissue”, naming as inventors Isaac OSTROVSKY, Michael MADDEN, Jon T. McINTYRE and Jozef SLANDA, the entire disclosure of which is hereby expressly incorporated herein by reference. However, those skilled in the art will understand that the probe of the treatment apparatus may be any device used for performing a medical procedure on tissue. For example, the treatment device may be used for delivering RF energy to tissue, may be a needle for injecting material to or removing material from a desired location, may comprise an imaging device or any other device that must be located within the vaginal canal of the patient in a position referenced to the urethra. The treatment may also be applied to another body lumen or cavity, where positional reference is made with respect to a different cavity.  
         [0020]     Treatment of SUI in female patients involves heating the endopelvic fascia that is attached to the urethra using a probe inserted into the vagina. The specific treatment location is dependent on the length and anatomical shape of the urethra. In general, the preferred location to place the probe and apply the energy approximately halfway along the length of the urethra, between the urethral meatus and the bladder neck. As shown in  FIG. 1 , the urethra  14  has a meatus  10  that is generally easy to recognize and to use as a reference for measurement purposes. The length of the urethra  14  between the meatus  10  and the bladder  16  may be used as the reference length to determine where to place the probe.  
         [0021]     As described above, it is difficult to accurately determine a position within from the vaginal canal  12  corresponding to the target distance along the urethra  14 . The variation in anatomy from one person to another is such that applying to the vaginal canal  12  a measurement derived form the urethra  14  can be very inaccurate leading to incorrect positioning of the probe. Numerous variations cause this inaccuracy. For example, the vaginal meatus  18  and the urethral meatus  10  may not lie in the same plane. The vagina  12  and urethra  14  may not be perfectly parallel, as seen in  FIG. 1 , and thus may have different internal distances between two adjoining points. In addition, the length of the urethra  14  varies from person to person, making standardized distances difficult to use. Because of these reasons, it is difficult to determine how far to insert the probe into the vaginal canal  12  to properly target the desired tissue.  
         [0022]     The embodiments of the present invention allow the physician to measure the length of the urethra, and then insert in the vaginal canal the therapeutic energy delivery probe at the correct location with respect to the measured length. In a first step, the length of the urethra is measured, for example with a Foley catheter or with another measuring device suitable for the task. After measuring the length of the urethra, generally defined from the urethral meatus to the bladder, the physician determines the desired location for the treatment. Typically, the desired location to be treated is found at about half of the total measured length of the urethra.  
         [0023]     Once the desired location along the length of the urethra has been determined, the physician inserts into the urethra measuring element  33  including a transmitter  34 , as shown in  FIG. 2 , via natural opening of the urethra. Conventional methods may be used to determine how far to insert the measuring element  33  to reach the desired reference location such as, for example referring to visible markers along the length of the measuring element  33  or a device such as a catheter attached thereto. A medical probe  32  is then inserted into the vaginal canal  38 , through the vaginal opening. The probe  32  preferably comprises an energy source for heating and/or ablating the target tissue as desired for a particular application. For example, the probe  32  may comprise a source of acoustic energy such as ultrasound to heat target portions of the endopelvic fascia to treat SUI. A sensor  42  is placed in or on the probe  32 , where it can sense the signal emanating from the transmitter  34 . Those skilled in the art will understand that the transmitter  34  may be incorporated in the probe  32  with the receiver sensor  42  located in the measuring element  33  to achieve the same results described above. Alternatively, both the transmitter  34  and the receiver  42  may be located on the probe  32  with a signal reflecting element (not shown) incorporated into the measuring element  33 .  
         [0024]     In a different embodiment, the measuring element  33  is incorporated into a catheter or other similar device used to measure the length of the urethra  36 . In this manner, after the length of the urethra  36  is determined, the catheter may be removed only partially to place the transmitter  34  in the desired location within the urethra  36 . For example, distance markings may be placed externally on the catheter where they are visible to the physician, so that the transmitter  34  can easily be placed at the reference distance along the urethra  36  without using external measurement tools.  
         [0025]     As the probe  32  is moved along the length of the vaginal canal  38 , the receiver  42  senses the signal of the transmitter  34 , and determines when the two components are closest to each other. For example, a processor  50  process a signal from the receiver  42  to generate an output which the user may interpret to determine when a selected location of the probe  32  has been reached—e.g., when the probe is closest to the transmitter  34 . The output may be aural, visual or other as would be understood by those skilled in the art. For example, the display unit  54  may show a representation of the strength of the signal received by the receiver  42  from the transmitter  34 . The closer the transmitter  34  and receiver  42  are, the stronger the signal is, as reported visually or aurally. Those skilled in the art will understand that when the receiver  42  is nearest to the transmitter  34 , the probe  32  is at or nearly at a location corresponding to the reference position in the urethra  36 . Alternatively, the processor may display a computed distance between the components. Alternatively, as would be understood by those skilled in the art, pulsed signals may be generated by the transmitter  34  with a propagation time of the pulses being used to determine a distance the signal travels between the transmitter  34  and the receiver  42 .  
         [0026]     The transmitter  34  and the receiver  42  may use any of a variety of energy sources and operating principles to determine the distance therebetween. For example, acoustic energy, electromagnetic energy or optical energy may be generated by the transmitter  34  and received by the sensor  42 . Those skilled in the art will understand that as the probe  32  is moved within the vaginal canal  38 , a point at which a strength of the energy received is a maximum, will correspond to a minimum distance that the energy has traversed through tissue and, consequently, to a minimum separation between the probe  32  and the target location. In one exemplary embodiment, a transmitter located in the patient&#39;s urethra and a receiver placed in the vaginal canal may be repeatedly positioned within about +/−2 mm from the point of minimal distance.  
         [0027]     Once the probe  32  has been positioned in the desired reference location within the vaginal canal  38 , the physician commences therapeutic treatment by, for example, applying energy from the probe  32  to heat the target tissue—e.g., target portions of the endopelvic fascia.  
         [0028]     Another embodiment of the present invention utilizes a different principle to correctly position a therapeutic probe inside a body lumen or cavity. As shown in  FIGS. 3 and 4 , a device  100  for treating tissue near the vaginal canal  38  includes a distal, therapeutic head  102  housing a treatment apparatus (e.g., the ultrasound delivery unit  104 ) coupled to a proximal handle  106  with a positioning mechanism  108  mounted thereon. The positioning mechanism  108  includes a sliding stop member  110  mounted on the handle  106  for movement along a ridge  112 , which is substantially parallel to an axis of the device  100 . The mechanism also includes a locking screw  114  (or other locking mechanism) for fixing the stop member  110  in a desired position relative to the handle  106 .  
         [0029]     One specific embodiment of the treatment device according to the present invention provides a method of placing a treatment device within the vaginal canal  38 , such that the urethral meatus  118  is used as the reference point for measuring the urethral length as well as for placement of the device. Procedures to treat SUI in particular may benefit from this embodiment of the invention. This method eliminates placement errors that may result from variability of the urethral length from one patient to another. Since the urethral meatus  118  is well defined physically, it is easily identified during the procedure. It can thus be used as a positive stop for the sliding measuring mechanism described above.  
         [0030]     As shown in  FIG. 4 , the positioning mechanism  108  includes at least one abutting surface  116  extending from the stop member  110 . In one exemplary embodiment, the device  100  according to the invention includes two abutting surfaces  116  formed on the stop member  110 , on either side of the ridge  112 . The angular positioning of the abutting surfaces  116  relative to the body of the probe or therapeutic head  102  may be selected so that, when the abutting surfaces  116  rest in contact with a portion of the patient&#39;s body adjacent to the urethral opening, the therapeutic head  102  is in an orientation appropriate to carry out the treatment of the target tissue. For example, the abutting surfaces  116  may be designed to rest on the urethral meatus, and use it as a reference point to measure the length of the urethra and to position the therapeutic head  102  in the vaginal canal  38 .  
         [0031]     Using two abutting surfaces  116  that are disposed symmetrically about the ridge  112  facilitates the targeting of two regions of target tissue disposed symmetrically about the urethra  36 . This may be desirable, for example, in certain treatments for SUI, where regions of target tissue on both sides of the urethra  36  are treated. In a preferred embodiment, the abutting surfaces  116  are separated from a centerline of the therapeutic head  102  by a distance that is approximately equal to a distance between the openings of the vaginal canal  38  and of the urethra  36 . In one embodiment, devices having a range of sizes may be provided with different separations between the abutting surfaces  116 , to fit patients with different anatomies. Alternatively, a variety of conventional mechanisms may be employed to allow the user to vary this separation distance, preferably symmetrically by an equal amount for both abutting surfaces  116 .  
         [0032]     In normal use, as shown in  FIG. 5 , the physician performing the procedure with the device  100 , begins by measuring the distance between the opening to the urethra  36  and the base of the bladder  16  using a Foley catheter  17  or similar device, as is known in the art. The urethral meatus  118  may be used as the reference point for the measurement. Depending on where the target tissue is located along the urethra  36 , an appropriate percentage of the urethral length is used as the reference distance for treatment. For example, if the target portion of tissue is located halfway along the length X of the urethra  36 , half of the total measured urethral length (X/2) becomes the reference distance for the treatment.  
         [0033]     In a second step, the reference distance is measured from the treatment apparatus (e.g., a center of focus of energy projected by the ultrasound delivery unit  104 ) proximally along the device  100  to a stop position on the handle  106 . The user then loosens the locking screw  114 , slides the stop member  110  along the handle  106  until one or both of the abutting surfaces  116  are at the stop position and re-tightens the locking screw  114  to fix the stop member  110  and the abutting surfaces  116  in the desired position. As would be understood by those skilled in the art, detents or any other suitable mechanism may be substituted for the locking screw to maintain the stop member  110  and the abutting surfaces  116  in the desired position. A ruler or other type of measuring markings may be incorporated in the handle  106  to show, for example the distance between the sliding stop member  110  and the focal point of the delivered energy.  
         [0034]     Once the reference distance is set with the stop member  110  and the locking screw  114 , the user inserts the therapeutic head  102  into the vaginal canal  38 , and orients at least one of the abutting surfaces  116  to align with the urethral opening or meatus. The therapeutic head  102  is then inserted in the vaginal canal  38  until one or both of the abutting surfaces  116  contacts the tissue surrounding the opening to the urethra  36 . At this point a desired portion  119  of the therapeutic head  102  is positioned at a depth within the vaginal canal  38  that is substantially the same as the reference distance X/2, and is inserted at an angular orientation such that the energy generated is focused toward the target tissue.  
         [0035]     If it is necessary to focus energy on different regions of target tissue around the vaginal canal, the therapeutic head  102  may be rotated using the handle  106 . In this case the handle  106  may comprise two abutting surfaces  116  separated by a desired angle that cooperate with the sliding stop member  110 . When the treatment is complete in a first orientation with a first one of the abutting members  116  contacting the urethral meatus  118 , the device is turned by a predetermined angle using the handle  106 , so that the second one of the abutting surfaces contacts the urethral meatus  118 . The deposition of energy may then be carried out at the second location ensuring that the deposition of energy occurs at a desired angular orientation and at the reference axial distance.  
         [0036]     In some procedures, it may be necessary to make more than one energy application at different axial distances within the vaginal canal  38  corresponding, for example, to points at different reference distances along the urethra  36 . In this case, the sliding stop member  110  may be released and repositioned to the new distance, and the locking screw  114  may be again tightened. The probe&#39;s therapeutic head  102  is then inserted into the vaginal canal  38  until the abutting surfaces  116  abut the urethral meatus  118  at the new position and the application of energy is repeated.  
         [0037]     The present invention has been described with reference to specific exemplary embodiments. Those skilled in the art will understand that changes may be made in details, particularly in matters of shape, size, material and arrangement of parts. Accordingly, various modifications and changes may be made to the embodiments. The specifications and drawings are, therefore, to be regarded in an illustrative rather than a restrictive sense.