Abstract:
The present invention relates to the use of a low frequency ultrasonic device for the delivery and activation of collagen based foam sealants to a human and/or animal patient for sealing puncture wounds in vascular tissues. The ultrasonic vascular closure method relates to an ultrasonic generator, an ultrasound transducer, a chamber containing a foam sealant, a transducer tip, a radiation surface, an orifice located at the distal end of the chamber. The foam sealant is ejected into a puncture wound and activated with ultrasonic waves emitting from the radiation surface. The ultrasonic waves induce vibrations within the foam sealant, slightly warming the foam sealants to assist the rapid sealing the puncture. The ultrasonic waves also provide and anesthetic effect for the pain and discomfort from the puncture site.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to a low frequency medical device and methods for the sealing of tissue puncture wounds after surgical procedures. 
         [0002]    With improvement in medical devices and procedures, it is increasingly becoming possible to avoid the trauma and complications caused by open surgery using various transcatheter techniques. Some examples of these procedures include; angiography, percutaneous transluminal coronary angioplasty, stenting, atherectomy and catheter ablation. These new methods are being developed because they offer significant benefits with respect to patient recovery, potential complications and cost. The early discharge of patients undergoing these elective and interventional procedures hinges on the lack of bleeding complications at the access site after the procedure sheath is removed from the artery. The size of the access route, coupled with the routine administration of anticoagulants, creates a strong need to stop bleeding at the puncture site as quickly as possible. However, hemostasis must be achieved without producing clotting in the vessel just treated in order to prevent a potentially fatal myocardial infarction or thrombosis. 
         [0003]    Simple compression is currently the standard of care for managing vascular access sites following interventional cases. Compression includes the use of hand pressure, clamps and/or sand bags. To begin with, anticoagulant therapy typically has to be discontinued up to four hours prior to vascular closure in order to permit the patient&#39;s clotting capability to improve. During this period the patient must remain immobilized to prevent bleeding with the sheath in place. Upon sheath removal a nurse or technician holds direct pressure on the site for at least 30 minutes until thrombus forms to seal the access site. Once hemostasis has been achieved the patient must remain motionless for a period of time that may range from 4 to 24 hours to minimize the risk of dislodging the clot. Furthermore, the direct pressure necessary to close the vessel puncture may restrict blood flow within the vessel itself, causing unwanted complications to the patient. 
         [0004]    To overcome the problems associated with manual compression, the use of a variety of alternative methods have been developed. These systems commonly known include heat sealing, lasers, suture based systems, or various types of plugs or glues. Plugs may be made in many different shapes and may be created from a variety of materials. No matter what the material or the shape of the plug, accurate placement of the plug is desirable. Placement is particularly import with prior art plug systems which use some portion of the patient&#39;s blood to form a clot or other obstructions. 
         [0005]    Prior art closure systems include devices such as the one described in U.S. Pat. No. 5,626,601 to Gershoney. This particular system uses a balloon which can be inflated to prevent the closure material from entering the vessel. Once the plug material has been injected into the vascular access site and partially solidifies, the balloon is deflated and pulled through the plug material. Another prior art closure device invented by Kensey and described in U.S. Pat. No. 5,676,689, uses a biodegradable backstop to prevent a plug from entering the vessel. 
         [0006]    Prior art references that describe cauterization sealing of the vessel opening include U.S. Pat. Nos. 4,929,246; 5,810,810; and 5,415,657, which disclose the use of a laser or of radio-frequency (RF) energy that is transmitted to the blood vessel through a catheter to thermally fuse or weld the punctured tissue together. U.S. Pat. No. 6,656,136 to Weng et al, describe the use of high intensity focused ultrasound to cauterize the wound opening. 
         [0007]    The prior art devices do not effectively resolve the problems associated with alternative mechanisms to the use of compression for vascular sealing and do not provide the benefits of the present invention as described below. 
       SUMMARY OF THE INVENTION 
       [0008]    Apparatus and methods in accordance with the present inventions may resolve many of the needs and shortcomings discussed above and will provide additional improvements and advantages as will be recognized by those skilled in the art upon review of the present disclosure. 
         [0009]    The present inventions provide an ultrasonic vascular closure device for sealing a patient&#39;s tissue wound with a collagen material. A specific application for use in vascular sealing is described in detail as an exemplary embodiment of the invention. However, the device has applicability to the sealing of tissue puncture wounds generally. The present invention does not rely on the patient&#39;s blood to provide the seal between the plug and the tissue. Rather, the application of ultrasound to the collagen creates a matrix between the tissue and the plug. Therefore, extending hospital stay time for anticoagulant dissipation is not required. Furthermore, the time required to complete the procedure of the present invention can be completed in 5 to 10 minutes or less, rather than the 30 minutes to several hours required for compression techniques. The reduction in patient stay length and staff time can result in considerable cost savings. Furthermore, there is considerable less likelihood of the wound reopening after the patient is released, reducing costs as well as reducing risks to patient recovery from the procedure. 
         [0010]    The present invention includes injecting a collagen based foam sealant into a tissue puncture wound. The foam sealant is then activated with an ultrasonic device to seal the wound. The ultrasonic device includes an ultrasound generator, a movable ultrasound transducer, a transducer tip at the distal end of the ultrasound transducer, a radiation surface at the distal end of transducer tip, a cavity and a vascular closure device head. A transducer housing is fixedly attached to the ultrasound transducer. A transducer tip may be located at the distal end of the ultrasound transducer. The distal end of the transducer tip is configured as a radiation surface. 
         [0011]    The ultrasonic device also has a body to contain the transducer housing and proximal portions of the transducer tip; the body is slideably attached to a dispenser portion for ejecting the foam sealant from the chamber, through an orifice and into a tissue puncture wound. A dispenser portion forms the chamber that contains at least portions of the transducer tip including a radiation surface inside the chamber. Sliding the dispenser portion into the body reduces the volume of the chamber. The interface between the body and the dispenser portion is designed with a sealing function to prevent leakage of the foam sealant. 
         [0012]    An orifice is located at the distal end of the chamber. As an alternative embodiment to using the foam sealant alone, the chamber may also contain a thread as well as an anchor. When used, the anchor is placed in the chamber, transported to the distal end of the puncture and then ejected from the chamber through the orifice. The thread is preferably attached to the anchor and serves as a means to keep the anchor in place as well as to provide a mechanism to keep the anchor against the puncture. The thread may also be used to provide a structure reinforcing the foam sealant as the foam sealant is being ejected from the chamber, as it is being activated and after sealing to hold the anchor and foam sealant in place. Preferably all of the material of the foam sealant, anchor and thread are biodegradable or bioabsorbable materials and will eventually be replaced by tissue growth as the wound heals. 
         [0013]    The ultrasound energy generated at the ultrasound transducer is transmitted through the transducer tip causing vibration of the radiation surface. The ultrasound energy is then emitted from the radiation surface. As the chamber is collapsed, the radiation surface moves through the chamber toward the orifice and may extend through the orifice for optimal activation of the ejected foam sealant. 
         [0014]    Other features and advantages of the invention will become apparent from the following detailed description and from the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  illustrates a cut away side view of aspects of an embodiment of an device according to the present inventions. 
           [0016]      FIG. 2  illustrates a cut away side view of aspects of an embodiment of an device according to the present inventions. 
           [0017]      FIG. 3  illustrates a side view of the ultrasonic tip of the ultrasonic device to the present invention. 
           [0018]      FIG. 4A through 4E  show several sequential views of selected stages for a f use according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    The figures generally illustrate embodiments of an ultrasonic device  10  including aspects of the present inventions. The particular exemplary embodiments of the ultrasonic device  10  illustrated in  FIGS. 1-4  have been chosen for ease of explanation and understanding of various aspects of the present invention. These illustrated embodiments are not meant to limit the scope of coverage but instead to assist in understanding the context of the language used in this specification and the appended claims. Accordingly, many variations from the illustrated embodiments may be encompassed by the appended claims. 
         [0020]    The present invention provides an ultrasonic device  10  for sealing a patient&#39;s tissue puncture wounds using ultrasound radiation. As illustrated in  FIGS. 1 and 2 , the ultrasonic device  10  includes an ultrasound generator connected to an ultrasound transducer  50  through a releasable connector  70 . 
         [0021]    A transducer housing  55  is fixedly attached to the ultrasound transducer  50 . The transducer housing  55  constructed preferably of aluminum, may also be constructed of titanium alloy, stainless steel or other material as known in the art. Preferably, as shown in  FIG. 3 , the vibration transmissions to the transducer housing  55  from the ultrasound transducer  50  are dampened through an isolation seal  65  using an assembly of O-rings which also provides a means to allow expansion of the ultrasound transducer  50  independently from the transducer housing  55 . 
         [0022]    A transducer tip  60  may be located at the distal end of the ultrasound transducer  50 . The distal end of the transducer tip  60  is configured as a radiation surface  90 . The ultrasound energy generated by the transducer  50  is transmitted to radiation surface  90  by ultrasonic vibrations induced in tip  60 . Upon reaching radiation surface  90 , the vibrations are released as ultrasonic waves carrying ultrasonic energy. Accordingly, the ultrasound energy generated by transducer  50  is emitted from radiation surface  90  into chamber  30 . A dispenser portion  25  forms a chamber  30  which is variable in size and contains at least portions of the transducer tip  60  including the radiation surface  90  as shown in  FIGS. 1 and 2 . 
         [0023]    An orifice  95  is located at the distal end of the chamber  30 . The chamber  30  contains a foam sealant  35  which is ejected from the chamber into the wound through the orifice  95 . Alternatively, as described below, the chamber  30  may also contain a thread  40  and an anchor  45 . 
         [0024]    Foam sealant  35  may be comprised of fiber forming proteins such as, but not limited to, collagen and/or elastin. In combination or in the alternative, foam sealant  35  may comprise glycoproteins associated with extracellular matrices such as, but not limited, laminin, entactin, and/or fibronectin. The foam sealant  35  is activated by the ultrasonic radiation energy to seal the wound. The ultrasonic energy released into chamber  30  enters foam sealant. As the energy propagates through the sealant  35 , the sealant begins to heat and vibrations are induced in the sealant. Consequently, the propagation of ultrasonic energy released from radiation surface  90  through sealant  35  activates sealant  35  by increasing its kinetic energy. Activating sealant  35  may make it easier to eject through orifice  95 . In combination or in the alternative, activation of sealant  35  may increase the degree to which the sealant diffuses into the surrounding tissue. Increasing the diffusion of the sealant into the surrounding tissue may better anchor the plug formed by the sealant. Sealant that has into the surrounding tissue may bind to integrins on the cells and/or various components of the extracellular matrix of the surrounding tissue. Binding to the cells and/or extracellular matrix of the surrounding tissue, the plug formed by the sealant becomes anchored within wound. Anchoring the plug within the wound may increase the integrity of plug. It is also possible that activation of the sealant may induce other reactions that better secure and/or increase the stability of the resulting plug. 
         [0025]    In combination or in the alternative, activation of the sealant  35  may induce the ionization, oxidation, generation of free radical and/or other chemical modifications within the sealant  35 . Chemically modifying sealant  35  may produce desirable effects such as increasing the sealant&#39;s integrity and/or the strength of its interactions with the tissue surrounding the wound. For example, the activation of a foam sealant comprised of collagen may lead to an increase prevalence of hydroxyproline and/or hydroxylysine with the collagen molecules. Increasing the prevalence of hydroxyproline may increase the amount of hydrogen bonding between the strands and/or surrounding tissue. Likewise, increasing the prevalence of hydroxylisne may increase the amount of covalent bonding between the collagen strands and/or surrounding tissue. Increasing the amount of binding between the collagen strands of the sealant and/or the tissue may better secure and increase the structure integrity of the plug produced from foam sealant  35 . 
         [0026]    The device also has a body  20  to contain the transducer housing  55  and proximal portions of the transducer tip  60 ; the body  20  is slideably attached to a dispenser portion  25 . As the dispenser portion  25  moves into the body  20 , the chamber  30  decreases in volume thereby ejecting the foam sealant  35  from the chamber  30 , through the orifice  95  and into a tissue puncture wound. The interface between the body  20  and the dispenser portion  25  is designed to include a seating means to prevent leakage of the foam sealant  35  past the adjacent surfaces. This surface may be sealed by conventional means such as flexible seals or by providing close tolerances between the surfaces. 
         [0027]    With reference to  FIGS. 4A-4E , the steps for sealing a tissue puncture wound are shown. As shown in  FIG. 4A , the proximal end of the dispenser portion  25  containing the orifice  95  is positioned near the tissue puncture wound. In vascular repair, this positioning can be assisted with or without various known scanning techniques which can be augmented through the use of known contrast agents. Following positioning of the device, as shown in  FIG. 4B  the anchor  45 , when used, is placed within the vascular lumen to be sealed at the distal end of the puncture wound. The foam sealant  35  and any other contents within the chamber  30  is then ejected into the proximity of the tissue puncture wound as shown in  FIG. 4C . Injection is accomplished by moving the dispenser portion  25  in the body  20  to decrease the volume of chamber  30 . 
         [0028]    Preferably, a spring  75  is biased between the body  20  and the dispenser portion  25 . As the dispenser portion  25  is slid into the body  20  the size of the chamber  30  is correspondingly reduced. As the chamber size decreases the contents of the chamber  30  which may include the foam sealant  35 , a thread  40  and the anchor  45  are ejected from the chamber  30 . Upon release of the compressive forces necessary to bias the spring  75  automatically returns the chamber  30  back to its original size. Depressing the transducer to eject the foam sealant  35  can be accomplished manually or through the use of a motorized drive. 
         [0029]    As the dispenser portion  25  is moved within the body  20  to collapse the chamber  30 , the radiation surface  90  which is fixed to the body  20  moves toward the orifice  95 . As shown in  FIG. 4D , the foam sealant  35  is then ejected from the chamber  30  and the radiation surface  90  may travel through the opening of the orifice  95 . The foam seal  35  is activated with the ultrasound emitted from the radiation surface  90  and the device is withdrawn. The activation can take from several seconds to a few minutes depending on the amount and composition of sealant  35 , size of the puncture and characteristics of the ultrasound applied. 
         [0030]      FIG. 4E  shows the sealed puncture with the anchor  45 , foam seal  35  and thread  40  left in place. These elements are preferably fabricated from bioabsorbable or biodegradable materials and will be replaced with natural tissue as the wound heals. 
         [0031]    When used, the anchor  45  may be fixedly attached to the thread  40 , all of which are placed or loaded next to the orifice  95  within the chamber  30  of the dispenser portion  25 . The anchor  45  will have a compact configuration for placement in the chamber and discharge through the orifice  95 . After discharge, the anchor  45  expands to a final configuration that is large enough so that it will not readily pass back through the orifice  95 . The anchor is preferably located within the vessel lumen to serve as a plug device to prevent the foam sealant  35  from dispersing into the vessel. The anchor  45  may be a of a variety of known devices that include compressible materials that expand when released, materials that swell when wetted, or may include rigid devices that can be collapsed, translated, folded and/or rotated for passing through the orifice  95 , but will unfold, expand, translate and/or rotate when ejected into the lumen. The anchor  45 , thread  40  and/or foam sealant  35  are preferably constructed of biodegradable or absorbable materials. Alternatively, the thread  40  may be semi rigid wire or wire bundle that breaks free of the anchor  45  and pulls through the foam sealant  35 . The anchor  45 , thread  40  and/or foam sealant  35  may have a therapeutic coating to assist healing. 
         [0032]    The anchor  45  is preferably attached to a thread  40 . The thread  40  is ejected with the anchor  45  and foam sealant  35 . The thread  40  is may be used to pull the anchor  45  firmly against the interior wall of the lumen. The thread  40  may function as a scaffold for sealant  35 . The thread  40  also serves to hold the anchor  45  in place and to prevent premature dislodgement of the anchor  40 . Preferably, the thread  40  may be composed of a biodegradable suture material. 
         [0033]    The foam sealant  35  preferably consists of a biodegradable material that is activated with ultrasound. The foam sealant  35  is placed in the chamber  30  and transported to the tissue puncture site. Exposing the foam sealant  35  to ultrasound energy may be initiated while the foam sealant  35  is within the chamber  30 . Doing, this may assist in ejecting of the foam sealant  35  into the wound. Furthermore, the foam sealant  35  serves as a coupling media to transfer the ultrasound waves into the tissue of the patient. 
         [0034]    Preferably, the foam sealant  35  is ejected from the chamber  30  and then activated. Ultrasonic stimulation of the foam sealant  35  and tissue puncture wound provides numerous beneficial effects. The ultrasonic energy provides activation of the foam sealant some heat, vibration and stimulation. It is important to note that the low intensity ultrasound does not seal the puncture through cauterization with the associated problems and risks of tissue damage and other complications associated with high energy delivery. Instead, the low frequency ultrasound produces low levels of heat and vibration only sufficient to quickly activate the foam sealant  35 . This prevents bleeding without relying on the clotting characteristics of the patient&#39;s blood, reducing the likelihood of a potentially dangerous thrombosis. Alternatively, the thread  40  may be semi rigid wire or wire bundle that breaks free of the anchor  45  and pulls through the foam sealant  35 . 
         [0035]    In addition, low frequency ultrasound provides an independent beneficial anesthetic effect during its application which enhances patient comfort during the procedure. 
         [0036]    The ultrasound generator has a preferred power input in the range of 50 watts to 130 watts. A power source such as a battery or AC supply may be connected to the ultrasound generator to provide electrical power to the ultrasound generator for generation of the electrical signal. The ultrasound generator may produce an electrical signal having various frequencies. The ultrasound generator may be configured to produce an electrical signal having a preselected constant signal frequency or may be configured to produce an electrical signal having a controllable variable signal frequency. The electrical signal then may be used to drive the ultrasound transducer  50  which may be a sinusoidal wave, square wave, triangular wave, trapezoidal wave, or any combination thereof. 
         [0037]    The ultrasound transducer  50  converts the electrical signal supplied by the ultrasound generator into a mechanical oscillation. The transducer tip  60  may be mechanically connected to the ultrasound transducer  50  so that the mechanical oscillation may be transmitted to the transducer tip  60  by the ultrasound transducer  50  to excite the transducer tip  60 . The mechanical oscillation has an oscillation frequency that generally corresponds to the signal frequency supplied to the ultrasound transducer  50  by the ultrasound generator. 
         [0038]    The ultrasound transducer utilized may be capable of vibrating in resonance at a frequency of between 16 kHz and 20 mHz, preferably 30 kHz. The ultrasonic vibrations traveling down the ultrasound transducer  50  may have an amplitude of approximately 1 to 300 microns with a preferred wavelength of 60 microns. 
         [0039]    The ultrasound tip  60  may be integral or removable from the ultrasound transducer  50 . Preferably, the ultrasound tip  60  is constructed from titanium alloy although stainless steel and other materials know in the art are also acceptable. Preferably the ultrasound tip  60  can be sterilized through convention means and preferably it is autoclavable. The ultrasound tip  60  is sized in proportion to its use. Preferably the ultrasound tip  60  has a maximum size between 0.1 to 0.5 cm for the distal end that enters the puncture. The ultrasound tip  60  distal end may be further restricted to a diameter preferably in the range of 0.05 to 0.3 cm for the portion that includes the radiation surface  90 . 
         [0040]    The ultrasonic waves traveling down the ultrasound tip  60  are emitted through the radiation surface  90 . The radiation surface  90  of the present invention may be formed in a variety of shapes, such as, but not limited to flat, angled, conical, concave or convex and/or any combination thereof. A flat surface may be preferred for embodiments that prefer production of parallel ultrasound waves rather than focusing or dispersing of the ultrasound waves. 
         [0041]    The radiation surface  90  may be positioned within the chamber as shown in  FIG. 4A  or the radiation surface  90  may be urged through the orifice to a position external to the chamber as represented in  FIG. 4D . Energizing the radiation surface  90  internal to the chamber utilizes the foam sealant  35  as a coupling medium for the ultrasound waves. This may be advantageous when the ultrasound energy may be used to activate the therapeutic agent either directly or indirectly through oxidation, ionization and/or, the production of free radicals and/or ozone. The potential for ultrasound to produce cavitation and micro-streaming can be utilized for some embodiments. 
         [0042]    Moving the ultrasound tip  60  and the radiation surface  90  within the chamber  30  assists with ejecting the foam sealant  35  from the chamber. The foam sealant  35  may be activated with the radiation surface  90  moved through the chamber  30  and the orifice  95  to a position external to the dispenser portion  25 . The foam sealant  35  is then activated with the low level ultrasonic energy to allow the foam sealant  35  to rapidly form a dependable seal of the puncture wound. As an added benefit, the ultrasonic waves may be used to activate a therapeutic agent, in addition, the ultrasonic waves themselves provide anesthetic effects as they interact with the nerve tissue adjacent to the wound. 
         [0043]    Although specific embodiments 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. It is to be understood that the above description is intended to be illustrative and not restrictive. The disclosed steps of the methods are not intended to be restricted to the order listed. Combinations of the above embodiments and; other embodiments 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.