Abstract:
An Ultrasonic apparatus and method is provided for the selective and targeted removal of unwanted tissues. The apparatus and methods may utilize combinations of ultrasonic and cryogenic energy for the selective removal tissue. The apparatus generates and delivers to the tissue cryogenic and ultrasonic energy, either in combination or in sequence, provides resize ablation of unwanted tissue parts, and may be used on various body tissues including internal organs.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 11/250,870, filed Oct. 13, 2005, now U.S Pat. No. 7,572,268, the teachings of which are hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to the removal of tissue from a patient, and more particularly, to apparatuses and methods using combinations of ultrasonic and cryogenic energy to remove tissue. 
     2. Description of the Related Art 
     Generally defined as diseases affecting the skin, skin disorders are common ailments afflicting individuals. Skin disorders frequently affect multiple layers of the skin. Some common skin disorders include wrinkles, scars, warts, non-metastsis melanomas, basilomas, human papillomaviruses, and various pre-cancerous or cancerous skin growths. Typical methods for treating skin disorders include surgical removal, chemical peeling, cryogenic destruction of diseased tissue, and various electrical treatments. 
     SUMMARY OF THE INVENTION 
     The present invention is directed towards apparatuses and methods for the selective ablation of unwanted tissue. Delivering ultrasonic and cryogenic energies simultaneously and/or sequentially, the present invention may destroy and/or remove unwanted tissue. The present may also be used to remove diseased tissue. External skin tissue and/or internal tissues of the body may be treated with the present invention. The present invention may be utilized for the selective removal of targeted tissue hard and/or soft tissue. 
     Combining the delivery of ultrasonic and cryogenic energy during treatment, the present invention may provide advantages over existing methods and devices for removing unwanted and/or diseased tissue. One advantage may be avoiding the adhesion of cold elements to the tissue during cryogenic ablation. Another advantage may be that the vibration created by the ultrasonic energy delivered to the tissue separates the unwanted and/or diseased tissue from healthy and/or wanted tissue. Another advantage may the destruction of microorganisms in the treatments by the delivered ultrasonic and/or cryogenic energy. Another advantage may be the creation of an analgesic effect on the treated tissue by the delivered ultrasonic energy. Delivering ultrasonic energy before, during, and/or after ablation may increase healing time and/or provide other positive benefits to the surviving tissue. 
     An apparatus in accordance with the present invention may be embodied as a hand held device having a proximate end and a distal end. The proximate end may comprise a handle. The distal end may comprise an ultrasonic tip. The ultrasonic may comprise a body. The body may define one or more chambers. Delivering a cryogenic fluid, such as, but not limited to, a liquid or gas, into one or more of the chambers may cool the ultrasonic tip. Transferring thermal energy away from the tissue, the ultrasonic tip when sufficiently cooled and placed proximate to the tissue may ablate unwanted and/or diseased by freezing the tissue. 
     Causing the tip to vibrate at an ultrasonic frequency, an ultrasonic transducer mechanically connected to the ultrasonic tip may be used to excite the ultrasonic tip. The ultrasonic tip may be simultaneously excited and cooled. Alternatively, the ultrasonic tip may be sequentially cooled and excited. Simultaneously transferring thermal energy away from the tissue and transmitting ultrasonic energy to the tissue, the cooled and excited ultrasonic tip, when placed proximate to a tissue, may selectively ablate the targeted tissue. Sequentially transferring thermal energy away from the tissue and transmitting ultrasonic energy to the tissue, the sequentially cooled and excited ultrasonic tip, when placed proximate to a tissue, may, in the alternative, selectively ablate the target tissue. Targeting selected tissue, the present invention removes diseased and/or unwanted tissue without unduly damaging healthy tissues surround the targeted tissue. 
     The cryogenic fluid may be delivered to the chambers of the ultrasonic tip&#39;s body through one or more connecting tubes or similar elements. Acting as inlets, the connecting tubes introduce cryogenic fluid from a reservoir into a chamber. Acting as outlets, the connecting tubes permit cryogenic fluid to flow through and/or out of a chamber. A chamber may be designed to approach the distal end of the ultrasonic tip. 
     Exciting the distal end of the ultrasonic tip may enable the transmission of ultrasonic energy to a tissue. The transmission of ultrasonic energy to a tissue may occur during, before, and/or after the transfer of thermal energy away from the tissue. The transmission of ultrasonic energy and/or the transfer of thermal energy may occur through direct contact of the ultrasonic tip with the tissue. Alternatively, an accumulation of frost on the tissue and/or the ultrasonic tip may act as a conduit for the transfer of thermal energy and/or transmission of ultrasonic energy. A spray of cryogenic fluid emanating from an orifice in the ultrasonic tip may also be used as a conduit for the transfer of thermal energy and/or transmission of ultrasonic energy. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a general diagrammatic overview of an embodiment of a system for the removal of tissue with a combination of ultrasonic and cryogenic energy. 
         FIG. 2  shows an apparatus in accordance with present invention and a plot of the amplitude of the mechanical vibration of the ultrasonic horn and ultrasonic tip elicited by the transducer. 
         FIG. 3  shows an alternative embodiment of an apparatus in accordance with the present invention comprising a narrow elongated a chamber extending towards the distal end the ultrasonic tip. 
         FIG. 4  illustrates an alternative embodiment of an apparatus in accordance with the present invention comprising a cryogenic fluid outlet tube defining an interior passage. 
         FIG. 5(   a ) is a side view of a chamber defined by the body of the ultrasonic tip. 
         FIG. 5(   b ) shows a cross-section of an embodiment of the ultrasonic tip with two chambers. 
         FIG. 6  illustrates cross-sectional views of different possible embodiments of the distal end of the ultrasonic tip. 
         FIG. 7  illustrates the delivery of cryogenic fluid through a lumen passing through the center of the ultrasonic transducer and the horn before connecting to a chamber within the body of the ultrasonic tip. 
         FIG. 8  illustrates an alternative embodiment of the ultrasonic tip comprising an orifice between a chamber within the ultrasonic tip and the distal end of the ultrasonic tip. 
         FIG. 9  illustrates an embodiment of the delivery of cryogenic and ultrasonic energy to the tissue through an accumulation of frost positioned between radiation surface and the tissue. 
         FIG. 10  illustrates an embodiment of the delivery of ultrasonic energy to the tissue through a cryogenic spray emitted toward the tissue from the radiation surface. 
         FIG. 11  presents a three-dimensional view of an alternative embodiment of the ultrasonic tip comprising multiple orifices on distal end of the ultrasonic tip. 
         FIG. 12  shows a backwards cone shaped distal end focusing ultrasonic energy on a focal point. 
         FIG. 13  shows a concave distal end focusing ultrasonic energy on focal point. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is directed towards apparatuses and methods for the selective ablation of unwanted and/or diseased tissue by delivering ultrasonic and cryogenic energies simultaneously and/or sequentially to the tissue to be ablated. Embodiments of the present invention may result in a highly controllable and precise ablation of tissue. 
     A general view of an embodiment of one apparatus  10  in accordance with the present invention is depicted in  FIG. 1 . The apparatus of the present invention  10  may be a hand held device with a distal ultrasonic tip  1 . Ultrasonic tip  1  may be used to deliver cryogenic and ultrasonic energy to the tissue area  9 . Ultrasonic tip  1  comprises a body defining one or more interior chambers  7  into which cryogenic fluid  20  flows. Cryogenic fluid  20  may be a liquid and/or gas. One example of possible cryogenic fluid is liquid nitrogen. Other suitable cryogenic fluids are readily recognizable by people of ordinary skill in the art. Cryogenic fluid  20  may be delivered to the interior chambers  7  from a source  5  through delivery tube  4 . Delivery tube  4  is attached to the ultrasonic tip  1  at the inlet tube  16 . Defining an interior passage  17 , inlet tube  16  connects delivery tube  4  to chambers  7 . Ultrasonic transducer  3  may be connected to an ultrasound generator  6  by a cable  11 . Ultrasonic tip  1  provides an ultrasonically active distal end  14  and/or cryogenic energy to tissue  9  through direct contact or through accumulation of frost  22 . 
     Creating accumulation of frost  22  on distal end  14  of the ultrasonic tip  1  may be accomplished by allowing moisture from the air to condense and freeze on distal end  14 . Alternatively, a substance such as, but not limited, water may be placed on distal end  14  and allowed to freeze. 
     Ultrasonic tip  1  is usually made from a metal such as titanium. Ultrasonic tip  1  may also be made from plastic and disposed of after treatment. Ultrasonic tip  1  may be excited by ultrasonic transducer  3 . Ultrasonic tip  1  may be connected to ultrasonic transducer  3  through an ultrasonic horn  2 . Ultrasonic tip  1  may be a separate piece attachable to ultrasonic horn  2 . Alternatively, ultrasonic tip  1  and ultrasonic horn  2  may form a single piece. Ultrasonic transducer  3  typically receives power from generator  6  through cable  11 . Ultrasonic transducer  3  may be pulsed according to a drive signal generated by generator  6  and transmitted to ultrasonic transducer  3  by cable  11 . The drive signal may be rectangular, trapezoidal, sinusoidal, or other signal types readily recognizable by those skilled in the art. Ultrasonic transducer  3  may be made to operate a frequency of approximately 18 KHz to approximately 20 MHz. The preferred frequency of operation is approximately 20 KHz to approximately 60 KHz. The recommended frequency of operation is approximately 35 KHz. The amplitude of the ultrasonic waves generated by transducer  3  may be approximately 1 micron to approximately 200 microns. The preferred amplitude of the ultrasonic waves generated by transducer  3  is approximately 50 microns. 
       FIG. 2  shows an apparatus in accordance with present invention and a plot of the amplitude of the mechanical vibration of ultrasonic horn  2  and ultrasonic tip  1  elicited by transducer  3 . Delivery tube  16  defines interior passage  17 , which opens into chamber  7 . Delivery tube  16  is attached to ultrasonic horn  2  approximately at the mechanical resonance node  28 . A resonance is node is a point where the vibration amplitude of ultrasonic horn  2  or tip  1  is zero. 
       FIG. 3  shows an alternative embodiment of an apparatus in accordance with the present invention. Ultrasonic tip  1 , in the depicted embodiment, comprises a narrow elongated chamber  7  extending towards distal end  14 . 
     Providing more than one chamber  7  may increase the efficacy of cryogenic ablation. 
     Chamber  7  may direct cryogenic fluid through one or more orifice  12  in distal end  14  ( FIGS. 8 ,  9 , and  10 ) or one the radial surface of ultrasonic tip  1  ( FIG. 11 ). 
       FIG. 4  illustrates an alternative embodiment of an apparatus in accordance with the present invention comprising a cryogenic fluid outlet tube  18  defining an interior passage  19 . Permitting the escape of cryogenic fluid from chamber  7 , tube  18  enables the circulation of cryogenic fluid through chamber  7 . 
       FIG. 5(   a ) is a side view of a chamber  7  defined by body  30  of ultrasonic tip  1 .  FIG. 5(   a ) also shows a channel  32  extending through the distal portion of ultrasonic tip  1  and in fluid communication with chamber  7 . Such an embodiment may increase the efficacy of heat transfer between ultrasonic tip  1  and the cryogenic fluid  20 . A plurality of tubular passages  34  are also defined by the body  30 . Emanating from chamber  7  and extending towards distal end  14 , tubular passages  34  may allow cryogenic fluid  20  to approach the distal end  14  while the maintaining structural integrity of body  30 . 
       FIG. 5(   b ) shows a cross-section of an embodiment of ultrasonic tip  1  with two chambers  7 . The use of multiple chambers  7  may improve circulation of a cryogenic fluid. 
       FIGS. 6(   a ) to  6 ( i ) are cross-sectional views of different possible embodiments of distal end  14 . A rounded or oval distal end, depicted in  FIG. 6(   a ) may be useful for the ablation of large regions of tissue. A sharp cone distal end, depicted in  FIG. 6(   b ), may be useful the precise ablation of small regions of tissue. Flat distal ends, depicted in  FIGS. 6(   c ),  6 ( d ),  6 ( e ), and  6 ( f ), may be useful localized tissue ablation.  FIG. 6(   g ) shows a toothed distal end. 
     As shown in  FIG. 6(   e ), a disposable plastic cover  26  matching the geometric conformation of distal end  14  may be used to cover distal end  14 . 
       FIG. 7  illustrates the delivery of cryogenic fluid through a lumen  34  passing through the center of ultrasonic transducer  3  and horn  2  before connecting to chamber  7 . This particular embodiment may offer manufacturing advantages readily recognizable to those of ordinary skill in the art. 
       FIG. 8  illustrates an alternative embodiment of ultrasonic tip  1  comprising orifice  12  between chamber  7  and distal end  14 . Flowing from chamber  7  through orifice  12 , cryogenic fluid  20  emanates from distal end  14 , as shown in  FIG. 10 . Spraying the cryogenic fluid  20  on tissue  9  may allow for the creation of an accumulation of frost  22  on tissue  9 . This embodiment may also allow for the creation of an accumulation of frost  22  on distal end  14 , as shown in  FIG. 9 . 
       FIG. 11  presents a three-dimensional view of an alternative embodiment of ultrasonic tip  1  comprising multiple orifices  12  on distal end  14 . This embodiment may be useful for the ablation of tissue forming various lumens in the body such as, but not limited to, bloods vessels. 
       FIG. 12  shows a backwards cone shaped distal end  14  focusing ultrasonic energy on a focal point  44 . 
       FIG. 13  shows a concave distal end  14  focusing ultrasonic energy on focal point  44 . 
     The present invention may be useful for the selective ablation of unwanted and/or diseased tissue. A method in accordance with the present invention comprises the steps of transmitting ultrasonic energy to and transferring thermal energy from a tissue to be ablated. The transfer of thermal energy from the tissue may proceed, follow, and/or occur simultaneously with the transmission of ultrasonic energy to tissue. Transferring thermal energy from the tissue may be accomplished by providing cryogenic fluid  20  to distal end  14  and placing distal end  14  proximate to and/or in contact with the tissue to be ablated. Transmitting ultrasonic energy to the tissue may be accomplished by exciting distal end  14  by activating transducer  3  and placing distal end  14  proximate to and/or in contact with the tissue. 
     When ultrasonic energy and cryogenic energy are simultaneous delivered to tissue  9  distal end  14  should remain proximate to and/or in contact with the tissue until the unwanted tissue is ablated. 
     Alternatively, cryogenic energy and the ultrasonic energy may be applied sequentially to the tissue to be ablated. For example, a sequential application may begin by exciting distal end  14 , placing the distal end  14  proximate to and/or in contact with the tissue  9 , and then providing cryogenic fluid to the distal end  14 . The sequence may be reversed, in which case the sequence would begin by providing cryogenic fluid  20  to the distal end  14 , allowing an accumulation of frost  22  to form on the distal end  14 , placing the distal end  14  proximate to and/or in contact with the tissue  9 , and then activating the ultrasonic transducer. Combinations of sequential applications of cryogenic and ultrasonic energy and the simultaneous application of cryogenic and ultrasonic energy may be during ablation of tissue  9  as would be recognized by those skilled in the art. 
     Alternatively, thermal energy may be transferred away from the tissue by spraying the tissue  9  with a spray of cryogenic fluid  20  emanating from orifice  12  in distal end  14 . Exciting distal end  14  as cryogenic fluid  20  sprays from office  12  onto tissue  9  may enable the enable the simultaneous delivery of cryogenic and ultrasonic energy. 
     If an accumulation of frost  22  is allowed to form on distal end  14  or tissue  9 , the accumulation of frost  22  may be used a conduit for the transmission of ultrasonic energy to tissue  9  from distal end  14  and/or the transfer of thermal energy from tissue  9  to distal end  14 . 
     It should be appreciated that as used herein the delivery of cryogenic energy to a tissue is synonymous with transferring cryogenic away from a tissue. 
     It should be appreciated that as used herein the delivery of ultrasonic energy to a tissue is synonymous with the transmission of ultrasonic energy to a tissue. 
     It should be appreciated that elements described with singular articles such as “a”, “an”, and “the” or otherwise described singularly may be used in plurality. It should also be appreciated that elements described in plurality may be used singularly. 
     Although specific embodiments of apparatuses and methods have been illustrated and described herein, it will be appreciated by people of ordinary skill in the art any arrangement, combination, and/or sequence that is calculated to achieve the same purpose may be substituted for the specific embodiments shown. It is to be understood that above description is intended to be illustrative and not restrictive. Combinations of the above embodiments and other embodiments as wells as combinations and sequences of the above methods and other methods of use will be apparent to individuals possessing skill in the art upon review of the present disclosure. The scope of the present invention should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.