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

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to removal of tissue from a patient, and more particularly, to apparatus and methods using combinations of ultrasonic and cryogenic energy remove tissue.  
         [0003]     2. Description of the Related Art  
         [0004]     Human skin is the largest organ of the body and acts as an indicator reflecting the various internal and external health related ailments. The skin protects the body from the common physical, chemical, and microbiological invasion that humans are naturally exposed to in their everyday living environment.  
         [0005]     Skin disorders are generally defined as diseases affecting the skin. Skin disorders frequently affect multiple layers of skin. Some common skin disorders include wrinkles, scars, warts, non-metastasis melanomas, basilomas, and human papillomaviruses, and various pre-cancerous and cancerous skin growths. Some skin disorders are local growths in the skin caused by viral infections, which are typically not contagious.  
         [0006]     Typical methods for treating skin disorders include surgical removal, chemical peeling, cryogenic and electrical treatments. The methods frequently have the disadvantages of destroying surrounding healthy tissue, increasing infection rates, high rates of recurrence, and/or substantial pain or discomfort following the procedure. Further, many existing methods are complicated and imprecise. This lack of precision in targeting the unhealthy tissue can result in the failure to fully remove the necessary harmful tissue and also can result in damage to the surrounding healthy skin tissue. Any unhealthy tissue not removed can quickly become the basis for recurrence of the disorder. In addition, the treated tissue can become a point for introduction of infections or contaminants because of the damage to or destruction of surrounding tissues. Therefore, a need exists for apparatus and methods, which target and completely or effectively completely remove diseased tissues without damage to the surrounding tissues.  
       SUMMARY OF THE INVENTION  
       [0007]     The present invention is directed toward apparatus and methods for selective ablation of unwanted skin layers. Apparatus and methods in accordance with the present invention may meet the above-mentioned needs and also provides additional advantages and improvements that will be recognized by those skilled in the art upon review of the present disclosure.  
         [0008]     An apparatus according to the present disclosure delivers ultrasonic and cryogenic energies to the skin tissue either in combination or sequentially. Unwanted tissue layers may be destroyed and removed by this combined or the sequential application of ultrasonic and cryogenic energy. The apparatus may be utilized for the treatment of diseased tissues or unwanted tissue layers/growths located either superficially or internally in human and animal bodies. The apparatus can be used for targeted and selective ablation of soft and hard tissues.  
         [0009]     An embodiment of an apparatus in accordance with the present invention may be a hand held device having a proximate end and a distal end. The proximate end may include a handle so that the device may be apprehended and manipulated by a surgeon. An ultrasonic tip may be located on the distal end of the device. The ultrasonic tip can include a body, and the body may define one or more chambers. The ultrasonic tip may be cryogenically cooled by delivery of a cryogenic fluid from a reservoir into one or more chambers defined by the ultrasonic tip. An ultrasonic transducer may used to excite the ultrasonic tip. Thus, the ultrasonic tip may be simultaneously cryogenically cooled and excited by the ultrasonic transducer or may be sequentially cooled and excited by the transducer so that simultaneous and sequential combinations of cryogenic and ultrasonic energy may be created at the ultrasonic tip. The ultrasonic tip may then be placed on tissue targeted for removal so as to deliver cryogenic energy and ultrasonic energy either in combination or in sequence to the tissue targeted for removal.  
         [0010]     The cryogenic fluid will typically be in either a gas phase or liquid phase. A cryogenic gas or liquid may be used as would be recognized by those skilled in the art such as, for example, liquid nitrogen. The cryogenic fluid may be delivered to one or more of the chambers defined by the body of the ultrasonic tip. The cryogenic fluid may be delivered by one or more connecting tubes or other components designed to direct cryogenic fluid flow the chamber. In one aspect, one or more inlet tubes are provided in communication with the chamber to introduce the cryogenic fluid into the chamber and one or more exit tubes are provided to permit the cryogenic to be removed from the chamber or to flow through the chamber. In another aspect, the interior chamber may be designed to approach the distal end of the ultrasonic tip to more efficiently cool the distal end.  
         [0011]     The ultrasonic tip has an ultrasonically active distal end for delivering ultrasonic to the targeted tissue. This may be applied to the tissue in combination with, subsequent to, or prior to the application of cryogenic energy. The energy may be applied through direct contact, through an ice ball formed on the ultrasonic tip, or through cryogenic spray emitted from the ultrasonic tip. “Ice ball” as used herein, generally refers to the creation of ice particles or pieces as the term is typically used in reference to cryogenic therapy. Although the particles or pieces of ice, herein labeled as an “ice ball,” may have a rounded geometrical form and, the particles or pieces of ice making up the “ice ball” do not necessarily have to be in the geometric form of a ball as will be recognized by those skilled in the art.  
         [0012]     The ultrasonic tip is usually composed of a metal such as titanium, although the ultrasonic tip may also be composed of plastic or combinations of metal and plastic as would be recognized by those skilled in the art. An ultrasonic transducer may be used to excite the ultrasonic tip. The ultrasonic tip may be connected to the ultrasonic transducer by an ultrasonic horn. The ultrasonic tip may be detachable from the ultrasonic horn or permanent attached to the ultrasonic horn. A detachable ultrasonic tip may be disposable.  
         [0013]     In other aspects, the distal end of the ultrasonic tip may have various geometric shapes such as sharp edged, conical, toothed, waved, flat, rounded or a combination of shapes. The various shapes can be chosen as appropriate for various procedures to be performed on the tissue. A detachable ultrasonic tip can allow a surgeon to vary the geometric shape of the distal end as appropriate during the course of a procedure.  
         [0014]     In another aspect, an orifice connecting to the chamber may be located on the distal end so that an ice ball may be created or cryogenic fluid may be sprayed from the distal end.  
         [0015]     The apparatus of the present disclosure may be used to apply ultrasonic and cryogenic energy simultaneously and/or sequentially to ablate tissue. Simultaneous application of cryogenic and ultrasonic energy may be accomplished by providing cryogenic fluid to the distal end, activating the ultrasonic transducer, and then placing the distal end in contact with the tissue until the tissue is ablated.  
         [0016]     Alternatively, the cryogenic energy and the ultrasonic energy may be applied sequentially by the apparatus to the tissue that is to be ablated. For example, a sequential application may begin by activating the ultrasonic transducer, placing the distal end in contact with the tissue, and then providing cryogenic fluid to the distal end. The sequence may be reversed, so that the sequence would begin by providing cryogenic fluid to the distal end, placing the distal end in contact with the tissue, and then activating the ultrasonic transducer. Various combinations of sequential and simultaneous applications of cryogenic and ultrasonic energy could be used during an ablation procedure, as would be recognized by those skilled in the art.  
         [0017]     Cryogenic energy may be delivered to the tissue in different ways such as by providing cryogenic fluid to the ultrasonic tip and then placing the distal end in direct contact with the tissue. Alternatively, an ice ball on the distal end may be placed in contact with the tissue, or cryogenic spray emanating from an orifice in the distal end may be used to deliver cryogenic energy to the tissue.  
         [0018]     Combining ultrasonic energy with cryogenic energy can provides multiple benefits for the selective tissue removal process. One advantage of apparatus incorporating aspects of the present invention may be that adhesion of the ultrasonic tip to the tissue of the patient is avoided. Another advantage of apparatus incorporating aspects of the present invention may be that ultrasonic vibrations separate the tissue to be removed from healthy tissue. Another advantage of apparatus incorporating aspects of the present invention may be that high intensity ultrasonic energy alone may destroy the target tissue and merely be supplemented by the cryogenic effects. Another advantage of apparatus incorporating aspects of the present invention may be that ultrasonic energy makes the process less painful due to the pain relief effect resulting from the application of ultrasonic energy. Another advantage of apparatus incorporating aspects of the present invention may be that application of ultrasonic and cryogenic energy can have an antimicrobial effect for the treated and surrounding tissue. These and other novel aspects of the invention will become more apparent from the discussion and drawings below.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]      FIG. 1  is a general diagrammatic overview of an embodiment of a system for removal of tissues, which can provide a combination of ultrasonic and cryogenic energy;  
         [0020]      FIG. 2  illustrates an embodiment of an ultrasonic tip in accordance with the present invention configured to deliver cryogenic fluid from outside directly to the inside of the distal end portion of tip and through one blunt orifice inside;  
         [0021]      FIG. 3  illustrates an embodiment of an ultrasonic tip in accordance with the present invention configured to deliver cryogenic fluid through two blunt orifices inside;  
         [0022]      FIG. 4  illustrates an embodiment of an ultrasonic tip with two separate tubes from outside and two orifices inside for delivering cryogenic medium in and out;  
         [0023]      FIG. 5 ( a ) illustrates a cross-sectional front view of an embodiment of an ultrasonic tip with two separate tubes from outside and two orifices inside for delivering cryogenic medium in and out;  
         [0024]      FIG. 5 ( b ) illustrates a horizontal cross-section of an embodiment of an ultrasonic tip with two orifices;  
         [0025]     FIGS.  6 ( a ) to  6 ( i ) illustrate cross-sectional views of embodiments of different shapes of the distal end portion of an ultrasonic tip;  
         [0026]      FIG. 7  illustrates an embodiment of the delivery of cryogenic medium through a orifice of the transducer and ultrasonic tip;  
         [0027]      FIG. 8  illustrates cross-sectional view of an embodiment of an ultrasonic tip with the interior chamber communicating with an orifice to a radiation surface;  
         [0028]      FIG. 9  illustrates an embodiment of the delivery of cryogenic and ultrasonic energy to the tissue through an ice ball positioned between radiation surface and tissue;  
         [0029]      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;  
         [0030]      FIG. 11  illustrates a perspective view of an embodiment of the distal portion of an ultrasonic tip defining multiple orifices located on radial surfaces for tissue removal of body lumens (such a vessels, cavities, etc.) in perimeter or sidewalls;  
         [0031]      FIG. 12  illustrates an embodiment of an ultrasonic tip having a reverse cone shaped radiation surface for focusing ultrasonic energy to the tissue; and  
         [0032]      FIG. 13  illustrates an embodiment of an ultrasonic tip having a concave shaped radiation surface for focusing ultrasonic energy to the tissue.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0033]     The present invention relates to apparatus for ablation of tissues through a combination of ultrasonic and cryogenic energies and to methods of use of such apparatus. Highly controllable, precise delivery of ultrasonic and cryogenic energy simultaneously or in different sequence allows the destruction of unwanted tissues without damaging surrounding tissue.  
         [0034]     A general view of an embodiment of the present apparatus  10  is shown in  FIG. 1 . The apparatus of the present invention  10  may be a hand held device with a distal ultrasonic tip  1  that delivers ultrasonic and cryogenic energy in combination or in sequence to the skin tissue area  9  selected for treatment. The ultrasonic tip  1  is composed of a body, the body defining one or more interior chambers  7  for a cryogenic fluid  20 . The cryogenic fluid  20  may be such gases or liquids as would be recognized by those skilled in the art such as, for example, liquid nitrogen. The cryogenic fluid  20  may be delivered to the interior chamber  7  from a source  5  through a cryogenic fluid delivery tube  4  which is attached to the ultrasonic tip  7  at the cryogenic fluid inlet tube  16 . The cryogenic fluid inlet tube  16  defines an interior passage  17  connecting the cryogenic fluid delivery tube  4  to the one or more interior chambers  7 . An ultrasonic transducer  3  may be connected to an ultrasound generator  6  by a cable  11 . The ultrasonic tip  1  provides an ultrasonically active distal end  14  for delivering ultrasonic and cryogenic energy to the tissue  9  through direct contact, through ice ball  22 , shown in  FIG. 9 , or through cryogenic spray  24 , shown in  FIG. 10 .  
         [0035]     The ultrasonic tip  1  is usually made from a metal such as titanium. The ultrasonic tip  1  may also be made from plastic and used disposably. The ultrasonic tip  1  may be exited by an ultrasonic transducer  3 . The ultrasonic tip  1  may be connected to the ultrasonic transducer  3  through an ultrasonic horn  2 . Those skilled in the art will recognize that ultrasonic tip  1  can be a separate piece attachable to the ultrasonic horn  2  or the ultrasonic tip  1  and the ultrasonic horn  2  can be combined as a single piece. An ultrasonic transducer  3  is typically connected by cable  11  to an ultrasound generator  6 . The ultrasonic transducer is pulsed according to a driving signal generated by the ultrasound generator  11  and transmitted to the ultrasonic transducer  3  by cable  11 . The driving signals as a function of time may be rectangular, trapezoidal, sinusoidal, or other signal types as would be recognized by those skilled in the art. The ultrasonic frequency may be between 18 KHz and 20 MHz, or more. The preferable frequency is 20-60 KHz, and the recommended frequency is 35 KHz. The amplitude of the ultrasonic wave may be between 1 micron and 200 microns, or more.  
         [0036]      FIG. 2  is an illustration of ultrasonic transducer  3  with the interior passage  17  defined by the cryogenic fluid inlet tube  16  connected to the interior chamber  7  defined by the ultrasonic tip  1 . A plot of the amplitude of the mechanical vibration of the ultrasonic horn  2  and ultrasonic tip  1  is also shown in  FIG. 2 . The delivery tube  16  is attached to the ultrasonic horn  2  or ultrasonic tip  1  at the mechanical resonance node  28 , i.e. the point where the vibration amplitude of the ultrasonic horn  2  or ultrasonic tip  1  is zero. If tube  4  is not attached to the ultrasonic horn  2  or ultrasonic tip  1  at the resonant node  28 , the intensity of the ultrasonic energy at the distal end  14  will be attenuated.  
         [0037]      FIG. 3  shows construction of the ultrasonic tip  1  with the delivery of cryogenic fluid through a chamber  7  having a narrow elongated portion extending toward tip  14 . The number of chambers  7  must be at least one. In some embodiments, more chambers  7  may provider high efficacy of cryogenic ablation by increasing surface area. In other embodiments, a narrow elongated portion of a chamber  7  may direct cryogenic fluid to one or more orifices  12  on distal end radiation surface ( FIGS. 8, 9 , and  10 ) or on the radial surface ( FIG. 11 ).  
         [0038]      FIG. 4  illustrates an embodiment of an ultrasonic tip  1  having a cryogenic fluid inlet tube  16  that defines an interior passage  17  that connects the cryogenic fluid delivery tube  4  to the one or more interior chambers  7  and a cryogenic fluid outlet tube  8  that defines an interior passage  19  to the one or more interior chambers  7 . Cryogenic fluid may then be added to the one or more interior chambers  7  through the cryogenic fluid inlet tube  16  and removed from the one or more interior chambers  7  through the cryogenic fluid outlet tube  8  so that the cryogenic medium is circulated through the one or more chambers  7  of the ultrasonic tip.  
         [0039]      FIG. 5 ( a ) is a side view of a chamber  7  defined by the body  30  of an 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  which may increase the efficiency of heat transfer between the ultrasonic tip  1  and cryogenic medium. A plurality of tubular passages  34  are also defined by the body  30 . The tubular passages  34  emanate from the chamber  7  toward the distal end  14  so as to allow cryogenic fluid to approach the distal end  14  while maintaining structural integrity of the body  30 .  
         [0040]      FIG. 5 ( b ) shows a cross-section of an embodiment of an ultrasonic tip with two chambers  7  for improved circulation of a cryogenic fluid.  
         [0041]      FIG. 6 ( a ) to  6 ( i ) is a cross-sectional view of different shapes of the distal end  14 .  FIG. 6 ( a ) illustrates the rounded or oval distal end  14  which may be used for the ablation of larger regions of tissue  9 .  FIG. 6 ( b ) illustrates a sharp cone distal end  14 , which may be used for the precise ablation of smaller regions of tissue  9 . FIGS.  6 ( c ),  6 ( d ),  6 ( e ), and  6 ( f ) illustrate various flat distal ends  14  for localized tissue  9  ablation.  FIG. 6 ( g ) shows a toothed distal end  14 . A disposable plastic cover cap  26  that matches the geometrical form of the distal end  14  may be used to cover the distal end, as shown in  FIG. 6 ( e ).  
         [0042]     The various geometric configurations for the ultrasonic tip  1  shown in FIGS.  6 ( h ) and  6 ( i ) are specially designed for the ablation of unwanted tissue layers in body lumen, such as vessels, cavities, etc. The ultrasonic tip is designed for insertion into body lumen without damage to the surrounding tissue.  
         [0043]      FIG. 7  illustrates the delivery of cryogenic fluid  20  through a lumen  34  that passes through the center of ultrasonic transducer  3 , ultrasonic horn  2  and connects to the one or more chambers  7 . This particular embodiment may offer manufacturing advantages as will be recognized by those skilled in the art upon review of the present disclosure.  
         [0044]      FIG. 8  illustrates a cross-sectional view of an ultrasonic tip  1  having an orifice  12  between the chamber  7  and the distal end  14  so that cryogenic fluid  20  may flow from the chamber  7  through the orifice  12  so as to emanate from the distal end  14 . This type of embodiment allows the creation of an ice ball  22  on the distal end  14 , as shown in  FIG. 9 , and/or cryogenic spray as shown in  FIG. 10 . Cryogenic and ultrasonic energy can then be delivered to the tissue  9  through ice ball  22  and/or cryogenic spray between distal end  14  and tissue  9 .  
         [0045]      FIG. 11  presents a three-dimensional view of an ultrasonic tip  1  with the multiple orifices  12  located on the distal end  14  for ablation of body lumen walls and sidewalls (such a vessels, cavities, etc.) in perimeter.  
         [0046]      FIG. 12  shows the backward cone shape for a distal end  14  that focuses ultrasonic energy on a focal point  44  and  FIG. 13  shows the concave shape for a distal end  14  that focuses ultrasonic energy on a focal point  44 .  
         [0047]     An apparatus according to the present invention may be used for the selective ablation of unwanted skin tissue such as warts, moles, pre-cancerous skin growths, tumors, melanomas, and scars. In one exemplary technique for using the apparatus, the cryogenic and ultrasonic energy are applied simultaneously to the tissue that is to be ablated. This technique includes providing cryogenic fluid  20  to the distal end  14 , activating the ultrasonic transducer  3 , and then placing the distal end  14  either proximate to and/or in contact with the tissue  9  until the tissue is ablated.  
         [0048]     Alternatively, the cryogenic energy and the ultrasonic energy may be applied sequentially by the apparatus to the tissue that is to be ablated. For example, sequential application may begin by activating the ultrasonic transducer  3 , 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 , 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 used in combination with the sequential application of cryogenic and ultrasonic energy may be used during ablation of tissue  9  as would be recognized by those skilled in the art.  
         [0049]     Cryogenic energy may be delivered to the tissue by providing cryogenic fluid  20  to the distal end  14  and placing the distal end proximate to the tissue and/or placing the distal end in contact with the tissue  9 . Alternatively, an ice ball  22  on the distal end  14  may be placed in contact with the tissue, or cryogenic spray  24  from an orifice  12  in the distal end  14  may be used to deliver cryogenic energy to the tissue.  
         [0050]     Although specific embodiments and methods of use have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement that is calculated to achieve the same purpose may be substituted for the specific embodiments and methods shown. It is to be understood that the above description is intended to be illustrative and not restrictive. Combinations of the above embodiments and other embodiments as well as combinations of the above methods of use and other methods of use will be apparent to those having 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.