Patent Publication Number: US-2009228002-A1

Title: Electromagnetic energy assisted tissue penetration device and method

Description:
CROSS-REFERENCE TO A RELATED APPLICATION 
     The present application claims priority to U.S. provisional application Ser. No. 61/068,039, filed Mar. 4, 2008, entitled “Vessel remodeling and lumen modification.” The entire contents the aforementioned provisional application is incorporated herein by reference. 
    
    
     BACKGROUND 
     Various surgical procedures are performed by medical specialists such as cardiologists and radiologists, utilizing percutaneous entry into blood vessels. Usually, to facilitate cardiovascular procedures, a small gauge needle is introduced through skin and into a target blood vessel, often the femoral artery. The needle forms a puncture through the blood vessel wall at the distal end of a tract that extends through the overlying tissue. A guide wire is then introduced through the bore of the needle, and the needle is withdrawn over the guide wire. An introducer sheath is then advanced over the guide wire; the sheath and guide wire are left in place to provide access during subsequent procedures. The sheath facilitates passage of a variety of diagnostics and therapeutic instruments and devices into the vessel and its tributaries. Illustrative diagnostic procedures include angiography, intravascular ultrasonic imaging, and the like. Exemplary interventional procedures include angioplasty, antherectomy, stent and graft placement, emobilization, and the like. After this procedure is completed, the catheters, guide wire, and introducer sheath are removed, and it is necessary to close the vascular puncture to provide hemostasis and allow healing. 
     The most common technique for achieving hemostasis is to apply hard pressure on the patient&#39;s skin in the region of the tissue tract and vascular puncture to form a blood clot. Initially, pressure is applied manually and subsequently is maintained through the use of mechanical clamps and other pressure-applying devices. While effective in most cases, the application of external pressure to the patient&#39;s skin presents a number of disadvantages. When applied manually, the procedure is time-consuming and requires the presence of a medical professional for thirty minutes or more. For both manual and mechanical pressure application, the procedure is uncomfortable for the patient and frequently requires the administration of analgesics to be tolerable. Moreover, the application of excessive pressure can occlude the underlying artery, resulting in ischemia and/or thrombosis. Even after hemostasis has apparently been achieved, the patient must remain immobile and under observation for hours to prevent dislodgement of the clot and to assure that bleeding from the puncture wound does not resume. Renewed bleeding through the tissue tract is not uncommon and can result in hematoma, pseudoaneurisms, and arteriovenous fistulas. Such complications may require blood transfusion, surgical intervention, or other corrective procedures. The risk of these complications increases with the use of larger sheath sizes, which are frequently necessary in interventional procedures, and when the patient is anticoagulated with heparin or other drugs. 
     In recent years, several hemostasis techniques have been proposed to address the problem of scaling vessel wall punctures following percutaneous transcatheter procedures. In some cases bioabsorbable, thrombogenic plugs comprising collagen and other materials are placed proximal to the vessel wall puncture site to stop bleeding. The larger hemostasis plug stimulates blood coagulation in the vessel puncture site, but blocks the catheter entry tract, making catheter reentry more difficult, if required. Other existing procedures require the use of small dissolvable disks or anchors that are placed in the vessel to block or clamp the puncture hole. However, any device remaining in the vessel lumen increases the risk of thrombus formation. Such a device also can detach and cause occlusion in a distal blood vessel, which would likely require major surgery to remove. Other existing procedures include using needles and sutures delivered through catheters to ligate the puncture. These suturing procedures require particular skill. Suture material left in the vessel may cause tissue irritation that prolongs the healing process. Yet another existing procedure requires a procoagulant to be injected into the puncture, with a balloon catheter blocking inside the vessel lumen. However, in some cases, the clotting agent may leak past the balloon into the vessel lumen and cause stenosis. Still other existing procedures require the use of laser or of radio-frequency (RF) energy that is transmitted through the blood vessel through a catheter to thermally fuse or weld the punctured tissue together. All of the above procedures require either introducing and leaving foreign objects in the patient&#39;s body, and/or inserting a tubular probe of large diameter into the tissue channel left by the catheter in order to seal the puncture. 
     There is a need for an improved procedure for sealing a puncture left in a blood vessels and tissue after tissue penetration. 
     SUMMARY 
     The present invention via embodiments disclosed hereinafter and many other embodiments within the scope of the claims of this patent overcome the problems as set forth above and/or afford other related advantages. The current disclosure describes various embodiments for speedy healing and closure of the opening. It is an aim of the disclosed embodiments and many other embodiments within the scope of the claims of this patent to reduce bleeding resulting from tissue and vessel penetration and to expedite healing. 
     One aspect of the invention disclosed hereinafter is a device for penetrating tissue. This device includes a removable access member which has a distal end and a proximal end. The proximal end of the device can be connected to a source of electromagnetic energy. The device also includes a sheath which encompasses the access member in a way that allows connecting the proximal end of the access member to the source of electromagnetic energy. The device permits the energy to be transmitted to the tissue through the distal end of the access member in such a way that penetration of the tissue and withdrawal from the tissue are facilitated by the use of the electromagnetic energy. 
     One other aspect of the invention disclosed hereinafter is a method for penetrating a tissue in order to perform a medical procedure. The method includes creating an access tract through the tissue while applying electromagnetic energy with a device which includes a removable access member and a sheath encompassing the access member. The method further includes withdrawing the access member while leaving the sheath in place. A medical procedure is then performed, after which the sheath is withdrawn. 
     While the present invention deals with a minimally invasive opening and closing of a vessel, it is equally understood that the invention can also be used to penetrate trough other collagen containing tissue utilizing electromagnetic energy to minimize subsequent healing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention, including device, apparatus and method aspects, is illustratively shown and described in reference to the accompanying drawings, in which 
         FIG. 1  is an illustration of an embodiment of a device of the current invention, which includes a removable access member for conducting electromagnetic energy to tissue and a sheath; 
         FIG. 2   a  illustrates an assembled embodiment of the device with the sheath substantially encompassing the removable access member; 
         FIG. 2   b  shows an enlargement of the distal end of a assembled embodiment of the device; 
         FIG. 3   a  illustrates the use of the device in a needle like procedure to access the inside of a vessel; 
         FIG. 3   b  illustrates the use of the sheath, which is left if place after removing the access member, for accessing the inside of a vessel or tissue; 
         FIG. 4   a  demonstrates the use of an embodiment of the device of the present invention for closing the wound on the vessel; 
         FIG. 4   b  illustrates the shrinking of the wound on the vessel as electromagnetic energy is applied to the wound via the device; 
         FIG. 5  illustrates the use of a drop of saline held in place while withdrawing the device of the present invention from the vessel; 
         FIG. 6  shows a cross section of a bipolar embodiment of the access member having a hollow channel inside; 
         FIG. 7   a  shows a cross section of a monopolar embodiment of the access member utilizing a conducting guidewire inside; 
         FIG. 7   b  shows a cross section of an insulated embodiment of the conducting guidewire; 
         FIG. 8   a  shows a cross section of a blunt-ended embodiment of the access member with the guidewire inside; 
         FIG. 8   b  shows a cross section of a bipolar embodiment of the blunt-ended insulating access member having half-ring termini connected to the opposite poles of the source of electromagnetic energy via imbedded conductive filaments; 
         FIG. 8   c  shows a cross section of the bipolar access member embodiment with the terminal conducting half rings shaped in to a cut-off cone; 
         FIG. 9   a  shows a source of electromagnetic energy connected to a clamp that may be used to connect the source to an insulated guidewire; 
         FIG. 9   b  shows a cross section of the clamp electrically connected to an insulated guidewire by cutting through insulation; 
         FIG. 9   c  shows the guidewire stabilized at a predetermined position with respect to the access member with the clamp which is stopped and stabilized by a hub placed at the proximal end of the access member; 
         FIG. 10   a  shows a cross section of a prior art hypodermic needle; 
         FIG. 10   b  shows a cross section of the hypodermic needle covered with an insulating sheath; 
         FIG. 10   c  shows a cross section of a hypodermic needle having an electromagnetic energy conducting guidewire inside; 
         FIG. 10   d  shows a cross section of the insulated hypodermic needle having an electromagnetic energy conducting guidewire inside; 
         FIG. 11   a  shows a cross section of a hypodermic needle with a guidewire with a distal end complementary to the shape of the distal end of the needle; 
         FIG. 11   b  shows a cross section of a hypodermic needle with a guidewire which is equipped with a conductive tip; and 
         FIG. 11   c  shows a cross section of the assembly of a hypodermic needle with a guidewire having a physiological saline solution filling the space between the needle and the guidewire. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The current disclosure describes specifically various embodiments of a device, apparatus and a procedure of delivering electromagnetic energy to a vessel tissue or other mammalian tissue which allows creating a substantially round shaped opening on the tissue while minimizing the size of the opening followed by promoting speedy healing of the resulting wound on the tissue by shrinking the collagen in the tissue. The procedure employs a device which utilizes electromagnetic energy to effectuate minimally invasive collagen containing tissue penetration and using the device for opening and closing a vessel or other tissue. 
     One such embodiment of the device of the invention is illustrated in  FIG. 1 ,  FIG. 2   a  and  FIG. 2   b . The device comprises a removable access member  10  and a sheath  20  which can encompass the access member  10 . The access member  10  has a distal end  60  and a proximal end  70 . The distal end  60  of the access member  10  is used for transmitting electromagnetic energy to the tissue, while the proximal end  70  is connected to a source of electromagnetic energy (not shown). Such source can be a source of electricity; heat; infrared, visible, or UV light, ultrasound, etc. 
     Illustratively, the device utilizes an electric energy source which is connected to the proximal end  70  of the access member  10  via an electrical cord  50  but is not limited hereto. In this embodiment the access member  10  has conductive properties and the sheath  20  has insulating properties. The cord  50  or other transmitting component may be removably connected to the proximal end  70  of the access member  10  with any suitable connector. For example, such a connector can be a luer-type connector with a male luer adapter  30  attached to the proximal end  70  and a matching female adapter  40  attached to the cord  50 . The assembled device  110  of the current embodiment is shown in  FIG. 2   a  and  FIG. 2   b .  FIG. 2   a  shows sheath  20  encompassing access member  10 , while  FIG. 2   b  shows an enlarged view of the distal end of the assembly marked with a circle  100  in  FIG. 2   a . The tip  80  of the access member  10  is positioned with respect to the sheath as to allow transmission of electromagnetic energy to the target tissue. For example, the tip  80  can be slightly protruding beyond the distal edge  90  of the sheath  20 , as shown in  FIG. 2   b . Applying electromagnetic energy allows utilizing a needle-like procedure to penetrate through tissue with a non-sharp device  110  as shown in  FIG. 2   a  and  FIG. 2   b . The tip  80  of the access member  10  of such a device can be of a blunt shape, as shown in  FIG. 2   b , with a round cross section but not limited hereto. Utilizing such a tip  80  to penetrate through vessel tissue or other tissue while applying electromagnetic energy to the tissue through the access member  10  results in a vessel opening of a substantially round shape. An illustrative example of using the device  110  of the current invention for accessing inside a vessel is shown in  FIG. 3   a  and  FIG. 3   b . First the assembly of sheath  20  encompassing access member  10 , while applying electromagnetic energy to tissue through access member  10 , is used to penetrate through tissue and inside the vessel  130 , as shown in  FIG. 4   a . Subsequently, access member  10  is removed from sheath  20 , while leaving sheath  20  in place. Then sheath  20  can be used for accessing inside the vessel  130  or other tissue with, for example, a catheter  140  utilizing a guidewire  120 , or with other suitable diagnostic or therapeutic instrument. Control bleed back  150  can be used for positioning the device inside the vessel and for confirming vessel penetration. 
     One of the embodiments of the method of the current invention can be illustrated with the following example. The access member  10  is placed into the removable sheath  20 , for example, but not limited to, 6 French size (2 mm approximate diameter). The sheath  20  insulates the entire access member  10  except the distal tip  60 , as shown in  FIG. 2   a . A power cord  50  which is attached to the proximal end  70  of the access member  10  is plugged into a standard electric source, such as, but not limited to, an operating generator (not shown). 
     For example, in preparation for applying the assembly  110 , user, such as a physician, pulpates the vessel, for example a femoral vessel, to determine puncture location, and positions the assembly  110  accordingly. During the preparation the assembly  110  is less prone to accidentally puncturing the patient or the physician as the tip of the assembly  110  in not sharp. Electromagnetic energy, for example, but not limited to, in the radio frequency range, is then applied to the assembly  110  which is inserted through dermis  160  and subcutaneous tissue  170  approximately 2.5 cm deep, such that it is slightly above the vessel  130 . The energy is turned off and the vessel  130  imaging is performed using, but not limited to, a suitable visualization system, such as computer tomography (CT) or ultrasound, or simply confirming that no vessel  130  access has yet occurred by performing a back bleed test  150  by loosening the proximal end  70  connector  30  on the access member  10 , which can be a luer connector. No blood should be observed. 
     Upon completing position verification the used re-applies the energy and inserts the device  110  approximately, but not limited to, 5 mm deeper then turns off the energy. At this point the vessel  130  has been accessed which can be confirmed by CT, ultrasound or a simple back bleed test  150  in which a spurt of blood should be observed (see  FIG. 3   b ). Utilizing this energy off and on method allows the user greater axial depth control so that the vessel is not pierced all the way through. In the latter case repositioning to another site would be required which is not desirable and time consuming. 
     After the access of the vessel  130  has been accomplished the user withdraws the access member  10  while leaving the sheath  20  in place. Loosening the luer adapter  30  and disconnecting the access member  10  from the source of energy can be used, for example, to facilitate the removal. A component, such as a guidewire  120 , is then introduced through the bore  180  of the sheath  20  into the vessel  130 , also a length of such component can be introduced into the lumen of the vessel. The guidewire  120 , or other component, is left in place to assist in vessel access during subsequent procedures. The sheath  20  facilitates passage of a variety of diagnostic and therapeutic instruments and devices into the vessel  130  and its tributaries. The method and the device of the current invention eliminates the need for a step of inserting the sheath after the guidewire. The method and the device of the current invention prevents excessive bleeding and leaving behind any foreign materials in the patient&#39;s body. 
     At the end of the diagnostic and/or therapeutic procedures the catheters, wires, etc. are removed from the sheath  20  but the sheath  20  is still left in place. The access member  10  is then reintroduced into the sheath  20  so that its distal tip is at the entry of wound  200  of the vessel  130 , as shown in  FIG. 4   a . Electromagnetic energy is then applied through the access member  10  while still within sheath  20 . With the access member  10  in place, remodeling of the collagen in the vessel  130  wall leads to the reduction in size of the diameter of the wound  200  (see  FIG. 4   b ). Subsequently, the user retracts the sheath  20  with the access member  10 . This procedure provides reduced back bleed due to the electromagnetic energy effect on the access tract  190  ( FIG. 3   a ) where the tissue cells around the circumference and full depth have been micro-cauterized. The latter effect leads to speedy hemostasis which reduces healing times compared to existing procedures. 
     Alternatively, the space  119  between the guidewire  120  and the sheath  20 , as shown in  FIG. 3   b , can be filled with a saline solution. A saline bleb  210  can be held in place at the distal end of the sheath  20  as the sheath  20  is withdrawn, as shown in  FIG. 5 . To optimize the location of the bleb an ultrasound, a fluoro contrast procedure, or another similar procedure can be used. Saline inside the sheath  20  can serve as the conductive media for transmitting electromagnetic energy from the generator to the bleb  210 . 
     Another embodiment of the device for penetrating tissue utilizing electromagnetic energy is shown in  FIG. 6 . This embodiment utilizes a bipolar conductive access member  10  having substantially rounded distal end  60  edges and a hollow channel  220  inside. The embodiment does not utilize a sheath. The opposite conductive sides  230  and  240  of the access member  10  are insulated from each other and are connected to the opposite poles of the source of electromagnetic energy. This trim access member  10  can have exposed conductive lead edges. The exposed conductive edges can be made by coextruding fine conductive filaments  250  (e.g. thin wires) in otherwise non-conductive walls of the access member  10  (which can be, but is not limited to, a tube or a catheter) ensuring that the distal ends  260  of the filaments  250  are exposed and conduct electromagnetic energy into tissue when in contact with the tissue. Alternatively, a conductive bulb can be placed at the distal end  60 , as describe earlier. 
     Yet another embodiment of the device of the current invention is shown in  FIGS. 7   a  and  7   b . In this embodiment a combination of a conductive access member  10  with a conductive guidewire  120  is utilized, which access member  10  and the guidewire  120  are connected to the opposite poles of a source of electromagnetic energy, as shown in  FIG. 7   a . The surface of the guidewire  120  of the present embodiment can be insulated substantially in its entirety, as indicated in  FIG. 7   b  with thick solid lines  270 , leaving only the surface of its distal end  280  exposed, as shown in  FIG. 7   b . Utilizing electromagnetic energy to augment tissue penetration allows using access members  10  having substantially blunt distal ends  60 , as shown in  FIG. 8   a . Such an access member  10  may be made of a non-conductive material but having conductive filaments  250  imbedded into its walls for conducting energy to its distal end  60  which can terminate with edges made of a conductive matter  290 , as shown in  FIG. 8   b . This Figure shows a bipolar access member  10  terminating with conductive half rings  290  which are insulated from each other. The half rings can be shaped as to create a cut-off cone shaped distal edge  60  of the access member  10 , as shown in  FIG. 8   c.    
     A clamp connector  300  can be used for connecting the guidewire  120  to the energy source  310 , as shown in  FIG. 9   a . The clamp cuts through the insulation  270  on the guidewire  120  and establishes a conductive connection with the guidewire  120 , as shown in  FIG. 9   b . The clamp  300  can also serve a stopper-stabilizer function by not allowing the distal end  280  of the guidewire  120  to protrude beyond a predefined distance from the distal end  60  of the access member  10  and by stabilizing the guidewire  120  in place, as shown in  FIG. 9   c . A hub  320  can be placed at the proximal end  70  of the access member  10  to facilitate the stopping and the stabilization of the guidewire  120  to which clamp  300  is attached. 
     Still other embodiments of the device of the current invention is illustrated in  FIG. 10(   a - d ) and  FIG. 11(   a - c ). These embodiments utilize a conventional hypodermic needle, shown in  FIG. 10   a , as the conductive access member  10 . The outer surface of the needle can be insulated with a removable sheath layer, as shown with solid thick lines  330  in  FIG. 10   b , to promote distal only energy transfer  340  to the tissue. The sheath can be removed, for examples, by peeling away. A guidewire  120  having a round distal end  280  can be used in combination with the access member  10  of the current embodiment, as shown in  FIG. 10   c  and  FIG. 10   d  and as disclosed earlier. To promote easier tissue penetration the distal end of the guidewire of the present embodiment can be shaped to be complementary to the shape  350  of the distal end of the hypodermic needle  360 , as shown in  FIG. 11   a . A conventional non-conductive guidewire  370  can be equipped with a conductive tip  380  to be used in the current embodiment, as shown in  FIG. 11   b . As an alternative means for conducting energy to the tip of the guidewire  370  the standard physiological saline solution  390  can be used when placed into the space between the access member  10  and the guidewire  370 , as shown in  FIG. 11   c.    
     Although the invention has been described with respect to various embodiments, it should be realized that this invention is also capable of a wide variety of further and other embodiments within the spirit of the invention.