Patent Publication Number: US-2002002380-A1

Title: Ultrasonic clamp and coagulation apparatus with tissue support surface

Description:
FIELD OF THE INVENTION  
       [0001] The present invention relates, in general, to ultrasonic surgical devices and, more particularly, to a new ultrasonic surgical instrument and method including inactive tissue clamping surfaces positioned laterally on either side of a longitudinal ultrasonic blade.  
       BACKGROUND OF THE INVENTION  
       [0002] Ultrasonic surgical instruments are continuing to gain acceptance with surgeons as a replacement for a variety of conventional surgical instruments. The advantages of a single instrument that uses ultrasonic energy for cutting, coagulating, or welding tissue is of great value to the surgical community. Applying ultrasonic vibrational energy to tissue is rapid, results in minimal trauma and bleeding, and is sometimes referred to as “bloodless surgery”.  
       [0003] An elongated blade extends from the distal end of the ultrasonic surgical instrument and is ultrasonically vibrated to a resonance condition by a transducer assembly. Pressing the exposed vibrating blade against tissue transmits ultrasonic energy to the tissue. Due to the ultrasonic vibrations, a distal portion of the elongated blade oscillates rapidly in a proximal to distal manner relative to the longitudinal axis of the instrument. This rapid oscillation or proximal to distal movement of the elongated blade is known as excursion. Excursion is non-uniform along the exposed blade length, attaining a maximum at the distal end and decreasing toward the proximal portion of the exposed blade. Tissue effects are directly related to the excursion of the elongated blade, with the greatest tissue effects being obtained at or near to the distal end. Application of the distal end to tissue results in cavitation effects such as coagulation and emulsification, and the sides of the blade produce frictional effects such as coagulation and cutting.  
       [0004] Three elements control the tissue coagulation effects: pressure applied to the tissue by the active blade (i.e.: force), the amount of energy delivered to the tissue by the blade (i.e.: power), and the duration of the energy delivery (i.e.: time). Different tissue effects are obtained by varying these parameters and by using different portions of the elongated ultrasonic blade on tissue. Placing the side of the elongated blade against tissue produces a frictional interaction between the elongated blade member and the tissue. This frictional interaction creates heat within the tissue and coagulates tissue adjacent to the oscillating elongated blade. Continued application of energy to tissue (with the side of the blade) produces a tissue coagulation zone, which spreads away from the elongated blade producing an effect known as lateral thermal spread. Using the sides of the blade to cause lateral thermal spread has proven useful when hemostatically sealing vessels or welding portions of tissues together.  
       [0005] Clamping or compressing tissue together prior to the application of energy was found to facilitate the sealing and welding process. Good tissue welds are obtained by applying a combination of pressure and energy to a selected portion of tissue. First, tissue is clamped or compressed together into a desired tissue orientation and second, ultrasonic energy is applied to the compressed tissue to weld it together. Combining a clamping mechanism with the elongated blade ultrasonic instrument proved revolutionary with the surgical community.  
       [0006] One type of ultrasonic surgical instrument clamps tissue directly against the side of the elongated blade. This type of a clamp and coagulation instrument generally has a clamp arm that is moveable from a first position spaced away from the side of the blade to a second position clamped against the side of the elongated blade. Clamping tissue against the side of the elongated blade increases the transfer of energy to tissue and enhances tissue coagulation and cutting effects. Additionally, using the side of the elongated blade provides the surgeon with a large tissue bite. Examples of ultrasonic surgical instruments that clamp against the side of the blade are described in the U.S. Pat. No. 5,322,055 by Davison et al., and in a Japanese Laid-Open Patent Application (Kokai) No. 8-275951 by Mitsumasa Okada et al.  
       [0007] Another type of ultrasonic instrument uses the distal end of the elongated blade to cut, and has a tissue clamping mechanism spaced distally away from the elongated blade. The ultrasonic instrument has a pair of opposed jaws that are moveable from an open position to a closed position for compressing tissue therebetween. A central passageway extends longitudinally within the closed jaws for the passage of the elongated blade, and tissue is compressed laterally on either side of the advancing elongated blade. Examples of these types of ultrasonic surgical instruments can be found in U.S. patent application Ser. No. 6,004,335 by Vaitekunas et al. and in Japanese Unexamined Patent Application No. 9-253088 by Makoto Miyawaki et al.  
       [0008] Vaitekunas et al. teaches a surgical ultrasonic instrument that has a pair of flexible jaw members formed from a cantilever spring material. The flexible jaw members clamp upon tissue and are opened and closed by a conventional tube closure mechanism. A passageway or longitudinal slot is provided within each of the flexible jaws for the passage of an ultrasonic blade. A flat knife blade forms the distal end of the elongated blade and is aligned with the slots within the flexible jaws. The flat knife blade travels down the slots within the flexible jaw members cutting and coagulating the uncompressed tissue within the longitudinal slot.  
       [0009] The Makoto Miyawaki et al. surgical instrument has a pair of cantilever spring jaw beams extending from the distal end of the ultrasonic surgical instrument with rigid jaws extending from the jaw beams. The cantilever spring jaw beams are formed in a normally deflected open position and are opened and closed by a conventional tube closure mechanism. When closed, the rigid jaws clamp tissue laterally on opposite sides of the advancing blade. A narrow longitudinal passageway is provided between the rigid jaws for passage of the elongated blade.  
       [0010] Advancing the blade through the central within the passageway emulsifies or cuts the uncompressed portion of tissue directly in front of the blade, and coagulates tissue laterally to the moving blade. However, there is little lateral spread with these types of instruments and consequently, a narrow coagulation zone or tissue weld zone.  
       [0011] Tissue weld strength depends on two factors: compressing or clamping tissue at the weld site, and the surface area of the weld. Compressing the tissue sample before welding ensures the clamped tissue is homogeneous and all portions of the tissue are held in the desired configuration as the energy is applied. Assuming the tissue is properly compressed during welding, tissue weld strength will directly depend on surface area, i.e.: twice the weld area, twice the strength. Using the distal end of a blade member to cut and coagulate produces a narrow coagulation zone in uncompressed tissue, and a small tissue weld area.  
       [0012] Ultrasonic surgical instruments that use the side of the elongated blade to clamp produce a wide coagulation zone (caused by lateral thermal spread), however they lack the ability to clamp tissue laterally to the elongated blade. This reduces the potential strength of the tissue weld as portions of the coagulated tissue lie outside of the compressed tissue area, i.e.: outside of the tissue clamped between the clamp arm and the blade. Thus, tissue coagulated outside of the compressed tissue area is coagulated in an uncompressed condition, and weld strength suffers.  
       [0013] What is needed is an ultrasonic clamp and coagulation instrument that offers the advantages of all of the above ultrasonic surgical instruments by producing a wide tissue weld in compressed or clamped tissue. Therefore it would be advantageous to provide an ultrasonic surgical instrument that provides a substantially continuous pressure region that extends laterally on either side of the elongated blade member as well as against the blade member, and can weld this substantially continuous pressure region. In comparison, Vaitekunas et al. and Makoto Miyawaki et al. provide a non-continuous pressure region. They compress tissue laterally to both sides of the elongated blade, and provide uncompressed tissue in the path of the advancing elongated blade. Presently, there are no known ultrasonic surgical instruments that can provide the surgeon with the improvements and benefits described above.  
       SUMMARY OF THE INVENTION  
       [0014] The present invention is an end effector for an ultrasonic surgical instrument. The end effector has an ultrasonic blade having a proximal and a distal end. A clamping mechanism having a clamping surface is positioned opposite to the ultrasonic blade. The clamping mechanism is adapted to clamp tissue against the ultrasonic blade.  
       [0015] A first support surface is positioned laterally on a first side of the ultrasonic blade. The first support surface is isolated from the ultrasonic blade and facing at least a portion of the clamping surface. A second support surface is positioned on a second side of the ultrasonic blade. The second support surface is isolated from the ultrasonic blade and is facing at least a portion of the clamping surface.  
       [0016] The first tissue support surface is a first support beam and the second tissue support surface is a second support beam. The clamping mechanism has an outer sheath surrounding a distal portion of the ultrasonic blade and the first and the second support beams extend distally from a distal end of the outer sheath. The first and second support beams have a blunt distal end to reduce tissue trauma. The first and the second support beams are also cantilever springs. Additionally, in a preferred embodiment, the first and the second tissue support beams are thermally resistive.  
       [0017] First and the second tissue support surfaces also define a plane, the plane being generally parallel to a longitudinal axis of the ultrasonic blade.  
       [0018] In an additional embodiment, the first and second support surfaces have a support surface angle relative to the longitudinal axis of the ultrasonic blade. The support surface angle is between one degree and sixty degrees. Preferably the support surface angle is ten degrees.  
       [0019] The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, reference is made to the accompanying drawings and descriptive matter in which the preferred embodiments of the invention are illustrated. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0020] The novel features of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to organization and methods of operation, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in conjunction with the accompanying drawings in which:  
     [0021]FIG. 1 is a side elevational view of an ultrasonic surgical system wherein an improved surgical instrument of the surgical system is shown in a cross sectional view;  
     [0022]FIG. 2 is an enlarged isometric view of a distal end of the improved surgical instrument of FIG. 1 showing an end effector having a blade, a first and a second support beam, and a moveable clamp arm;  
     [0023]FIG. 3 is an enlarged isometric view of a distal end of a prior art surgical instrument, wherein the end effector has closed upon a vessel;  
     [0024]FIG. 4 is an enlarged cross sectional view of the distal end effector of the prior art surgical instrument of FIG. 3, wherein the end effector has closed upon a vessel;  
     [0025]FIG. 5 is an enlarged cross sectional view of the distal end of the prior art surgical instrument of FIG. 4 wherein the application of ultrasonic energy has coagulated and cut the vessel within the end effector;  
     [0026]FIG. 6 is an enlarged view of the coagulated and cut vessel of FIG. 5 after release from the prior art surgical instrument, wherein the coagulated tissue is identified by stippling;  
     [0027]FIG. 7 is an enlarged isometric view of the improved surgical instrument of FIG. 2, wherein the end effector has closed upon a vessel;  
     [0028]FIG. 8 is an enlarged cross sectional view of the distal end effector of the improved surgical instrument of FIG. 2, wherein the end effector has closed upon a vessel;  
     [0029]FIG. 9 is an enlarged cross sectional view of the distal end of the improved surgical instrument of FIG. 8 wherein the application of ultrasonic energy has coagulated and cut the vessel within the end effector and the severed vessels are clamped between the clamp arm and the first and second support beams;  
     [0030]FIG. 10 is an enlarged view of the coagulated and cut vessel of FIG. 9, after release from the prior art surgical instrument, wherein the coagulated tissue is identified by stippling;  
     [0031]FIG. 11 is an enlarged cross sectional view of the distal end of an alternate embodiment of the improved surgical instrument of FIG. 2, showing the clamp arm in an open position and the first and a second support beams in an angled position;  
     [0032]FIG. 12 is side elevational view of the distal end of the embodiment of the improved surgical instrument of FIG. 11, showing the end effector in a partially closed position and three possible tissue portion clamping locations within the end effector;  
     [0033]FIG. 13 is an enlarged cross sectional view of FIG. 12, wherein the end effector is shown partially closed upon a tissue portion at a distal end of the end effector and the tissue portion is clamped between the clamp arm and the first and second tissue support beams above the ultrasonic blade;  
     [0034]FIG. 14 is an enlarged cross sectional view of the improved surgical instrument of FIG. 13, showing the end effector arm in a fully closed position and the tissue portion clamped between the clamp arm and the blade prior to the application of ultrasonic energy; and  
     [0035]FIG. 15 is an enlarged view of the vessel of FIG. 14, wherein the vessel has been coagulated and cut and released from the end effector, and the coagulated tissue is identified by stippling. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0036] The present invention relates, in general, to a novel ultrasonic surgical instrument for the clamping and coagulation of tissue during a surgical procedure. More particularly, the present invention relates to an ultrasonic clamp and coagulation instrument having an improved tissue clamping mechanism that clamps tissue against a side of a longitudinal ultrasonic blade and has inactive tissue clamping surfaces located laterally on either side of the longitudinal ultrasonic blade.  
     [0037] Referring now to FIGS. 1 and 2, the ultrasonic surgical system  20  has an ultrasonic clamp and coagulation instrument henceforth referred to as surgical instrument  23 , an ultrasonic generator  21  for the generation of electrical signals, and an operator controlled generator actuation mechanism  22 . A cable  26  carries electrical signals from the generator  21  to the surgical instrument  23 . The surgical instrument  23  converts the electrical signals from the generator  21  into ultrasonic energy that is transmitted to a distal end effector  65  by a waveguide  61 . Ultrasonic energy is delivered to an elongated ultrasonic blade  66  of the end effector  65  at a resonant frequency suitable for the cutting, coagulating, and welding of body tissue. The ultrasonic energy may, for example be delivered at a frequency between 20 kHz and 250 kHz, and preferably at a frequency of 55 kHz. A moveable clamping mechanism  67  is located adjacent to the ultrasonic blade  66  for the clamping of tissue against the ultrasonic blade  66 . A phase lock loop control system is provided as a part of ultrasonic generator  21  to adjust the frequency of the electrical signals to match the resonant frequency of the surgical instrument  23 , and to change the frequency of the electrical signals when the ultrasonic blade  66  is subjected to a tissue load. A second feedback loop is provided as a part of generator  21  to maintain a constant electrical current level to control the excursion or proximal and distal movement of a distal end of the ultrasonic blade  66 . Generator actuation mechanism  22  is generally a foot-activated pedal that is used to activate the generator  21 . A suitable ultrasonic generator is the GEN01 Ultracision® Generator and a suitable foot pedal is the GEN03 Footswitch, both available from Ethicon Endo-Surgery, 4545 Creek Road, Cincinnati, Ohio.  
     [0038] The surgical instrument  23  is assembled from two components: an ultrasonic drive unit  25  for converting the electrical signals from the generator  21  into ultrasonic energy, and a handle assembly  45 . Handle assembly  45  has the ultrasonic blade  66   a  at a distal end and the clamping mechanism  67  for the clamping of tissue against the ultrasonic blade  66 . Ultrasonic drive unit  25  is removeably mountable within a receptacle  51  at a proximal end of a body  52  of the handle assembly  45 . An exterior housing  27  surrounds the ultrasonic drive unit  25  and isolates the components therein. Cable  26  enters a proximal end of the exterior housing  27  and is electrically connected to a stack of piezoelectric elements  28 . An acoustic assembly  28   a  is formed by compressing the stack of piezoelectric elements  28  between a proximal end bell  31  and a distal vibration transmission member  29 , and securing the compressed assembly with a bolt  32 .  
     [0039] Electrical signals from the generator  21  forces the piezoelectric elements  28  to undergo a rapid series of physical expansions and contractions. These expansions and contractions create a series of mechanical pulses or high frequency longitudinal waves of ultrasonic energy within acoustic assembly  28   a . A resilient mount  30  is attached to the vibration transmission member  29  to constrain the acoustic assembly  28   a  within the exterior housing  27 . Mount  30  also vibrationally isolates the acoustic assembly from the exterior housing  27 . The assembled surgical instrument  23  can be used in an un-powered mode to clamp or grasp tissue, or in a powered mode to coagulate, cut, or weld tissue. An example of a suitable ultrasonic drive unit  25  is the Model No. HP050, which is available from Ethicon Endo-Surgery, 4545 Creek Road, Cincinnati, Ohio. An example of a suitable handle assembly  45  is the LCS-15 also available from Ethicon Endo-Surgery, 4545 Creek Road, Cincinnati, Ohio.  
     [0040] The vibration transmission member  29  of the ultrasonic drive unit  25  removeably and operably couples to a waveguide  61  of the handle assembly  45  to make the ultrasonic clamp and coagulation apparatus  40 . A threaded connection (not shown) removeably and operably connects the vibration transmission member  29  of the ultrasonic drive unit  25  to a waveguide  61  of the handle assembly  45 . Waveguide  61  extend distally through the handle assembly  45  from the vibration transmission member  29  to the ultrasonic blade  66  located at the distal end of the waveguide  61 . Waveguide  61  is generally made of a material such as aluminum or titanium.  
     [0041] A shaft assembly  60  rotatably mounts into the body  52  and has an outer sheath  63  surrounding most of the waveguide  61 . Outer sheath  63  is an elongated tubular member vibrationally isolated from the waveguide  61  and has clamping mechanism  67  pivotably attached at its distal end. A rotation knob  62  is fixedly attached at the proximal end of outer sheath  63  and rotatably mounts within the body  52 . Rotation knob  62  rotates the shaft assembly  60  within the body  52 , and around the waveguide  61 . Clamping mechanism  67  has a moveable clamp arm  67   a  extending distally from the outer sheath  63  and adjacent to the ultrasonic blade  66 . Clamp arm  67   a  is pivotably attached (at the proximal end) to the outer sheath  63  by a pivot  69  and is moveable from an open position spaced away from ultrasonic blade  66  (FIGS. 1 and 2) to a closed position adjacent to ultrasonic blade  66  (FIG. 3). Pivot  69  defines a pivot axis about which clamp arm  67   a  pivots. An actuation member  64  is moveably located between outer sheath  63  and waveguide  61  and is operably coupled to the clamp arm  67   a  at a distal end. A drive collar  75  is fixedly attached to a proximal end of the actuation member  64  within the body  52 . Proximal and distal motion of the drive collar  75  within the body  52  closes and opens the clamping mechanism  67 .  
     [0042] A handgrip  46  extends fixedly downward from a distal portion of the body  52  and an operating lever  47  pivotably extends downward from the proximal portion of the body  52 . Operating lever  47  pivots about a pivot mount  48  and is operably and rotatably coupled to the drive collar  75  by a drive yoke  49 . Drive yoke  49  rotates about the pivot mount  48  and is operably coupled to the operating lever  47  by a force limiting spring  50 . An upper portion of the drive yoke  49  is “U” shaped and straddles the waveguide  61  (FIG. 1). A front portion of the drive yoke  49  is sectioned and removed in FIG. 1. A pair of opposed pins  49   a  extend inwardly within the “U” of drive yoke  49  to engage with a slot of the drive collar  75  (shown sectioned). A pin  49   a  (non-crosshatched) is shown sectioned in the proper position in the foreground for clarity. Proximal motion of the operating lever  47  opens the clamping mechanism  67  and distal motion of the operating lever  47  (dashed lines, FIG. 1) closes the clamping mechanism  67  against the ultrasonic blade  66 . Force limiting spring  50  limits the amount of closure force that can be applied against the ultrasonic blade  66 .  
     [0043]FIG. 2 is an enlarged view of the end effector  65  which has ultrasonic blade  66  for the delivery of ultrasonic energy to tissue and clamping mechanism  67  for clamping tissue against a blade surface  66   a  of the ultrasonic blade  66 . Clamp arm  67   a  is shown in the open position for the reception of tissue and is moveable to a closed position to clamp tissue against the ultrasonic blade  66  (FIG. 7). Clamp arm  67   a  is operatively connected to the actuating member  64 , which can be seen within outer sheath  63 . A resilient clamp pad  68  is located on the inner side of clamp arm  67   a  and has a clamping surface  68   a  facing the ultrasonic blade  66 . Clamp pad  68  vibrationally isolates clamp arm  67   a  from ultrasonic blade  66  when the clamp arm  67   a  is in the closed position. First and a second support beams  70 ,  72  having a first and a second support surfaces  71 , 73  respectively, flank the ultrasonic blade  66  on either side. First and second support surfaces  71 , 73  are ultrasonically isolated, e.g.: not in contact with and spaced away from the ultrasonic blade  66 , and extend along the entire length of the treatment region of ultrasonic blade  66  and the clamping surface  68   a . Support surfaces  71  and  73  are positioned opposite to and face the clamping surface  68   a  when clamp arm  67   a  is in the open position, and contact the clamping surface  68   a  when the clamp arm  67   a  is in the closed position. When tissue is positioned within the end effector  65 , first and second support surfaces  71 ,  73  compress or clamp tissue against clamping surface  68   a . First and second support beams  70 , 72  may be cantilever springs. Additionally, first and second support surfaces  71 ,  73  are positioned parallel to one another such that they are in the same plane with clamp arm  67   a  open. Support beams  70 ,  72  extend from the metallic outer sheath  63  and may include a blunt distal end  74  to provide an atraumatic tissue contact surface at the distal ends of support beams  70 ,  72 .  
     [0044] FIGS.  3 - 6  illustrate the prior art end effector  65   a , its method of use, and results when used upon tissue such as a vessel  35 . Due to the similarities between the prior art device and the preferred invention described above, like components, or nearly identical components, will have the same element numbers and descriptions with components having the same element numbers having the same function. Vessel  35  is shown draped over the ultrasonic blade  66  and clamp arm  67   a  in a closed position. The effects of applying ultrasonic energy to a vessel  35  in such a draped position will be described below.  
     [0045] Good hemostasis, coagulation, cutting, or tissue welding depends upon the application of both pressure and energy to tissue or vessels. FIG. 4 is a cross sectional view of the instrument illustrated in FIG. 3 and shows a sectioned end view of the prior art end effector  65   a  clamped on vessel  35 . Pressure is exerted upon the tissue of the vessel  35  by the clamped prior art end effector  65   a . A series of pressure streamlines  36  are shown within the vessel  35  to show the effects of pressure on a clamped vessel  35 . Pressure streamlines  36  are also used in FIGS. 8, 13, and  14 . Spacing between the pressure streamlines  36  varies to indicate areas of higher or lower compression. Closer spacing indicates areas of higher pressure. As shown, an angular portion of vessel  35  is clamped between the prior art ultrasonic blade  66  and the clamping surface  68   a  and is defined as a tissue compression zone α. The tissue clamped within the tissue compression zone α has pressure streamlines  36  that are close together to indicate the clamping pressure applied by clamp arm  67   a.    
     [0046] In FIGS. 5 and 6, ultrasonic energy has been applied to the clamped vessel  35  by the prior art end effector  65   a . The vessel  35  has been cut into a pair of severed vessels  35   a  and a portion of coagulated tissue  37  can be found at the end of each segment of the severed vessels  35   a . Stippling will henceforth be used to identify coagulated tissue. Upon cutting, the severed vessels  35   a  fall from the closed prior art end effector  65   a  (FIG. 6). The ends of the severed vessels  35   a  are composed of two different types of coagulated tissue: tissue compressed and welded together designated by welded tissue length “d”, and adjacent coagulated tissue (which is not welded) designated by coagulated tissue length “d′”. The welded tissue length “d” is composed primarily of tissue from within the angular tissue compression zone “α” and may include a small amount of additional welded tissue that is adjacent to but slightly beyond the compression zone “α”. The coagulated tissue length “d′” is caused by contact of an uncompressed portion of the severed vessel  35   a  against the ultrasonic blade  66 . Since pressure is not applied when this tissue is coagulated, coagulated tissue length “d′” is not welded.  
     [0047] FIGS.  7 - 10  illustrates the end effector  65  according to the present invention which is illustrated in FIG. 2, its method of use, and the results obtained when an end effector  65  according to the present invention is used on tissue. The end effector  65  differs from the prior art instrument of FIG. 3 in that the first and second support surfaces  71 , 73  are provided to clamp the vessel  35  against the clamping surface  68   a  laterally on either side of ultrasonic blade  66 . Tissue is also clamped between the clamping surface  68   a  and the ultrasonic blade  66 . The first and second support surfaces  71 , 73  are inactive or ultrasonically isolated from the ultrasonic blade  66 . FIG. 7 shows an isometric view of the end effector  65  of the present invention clamped upon a vessel  35  prior to the application of ultrasonic energy. FIG. 8 is a sectioned end view of the isometric view of FIG. 7 and used pressure streamlines  36  to show the areas of tissue compression. It is of note that the first and second support surfaces  71 , 73  of the present invention support the vessel  35  laterally on both sides of the ultrasonic blade  66 , and this lateral support creates a wider angular compression zone β against the ultrasonic blade  66  than the prior art end effector  65   a  (see FIG. 4). As shown by the pressure streamlines  36 , more of vessel  35  is compressed between the ultrasonic blade  66  and the clamping surface  68   a . Further, the pressure streamlines show the compression on the tissue is substantially laterally continuous across the end effector  65 . When the ultrasonic blade  66  is energized, the application of ultrasonic energy will produce a wider portion of compressed coagulated tissue i.e.: welded tissue.  
     [0048]FIGS. 9 and 10 show the effects of the application of ultrasonic energy to the clamped vessel  35  of FIG. 8. In FIG. 9, the ultrasonic energy has welded and cut the compressed portion of vessel  35  into two preferred severed vessels  38 . The preferred severed vessels  38  are welded at the ends and that the length of the welded tissue is designated by a welded tissue length “ω”. Note that the first and second support surfaces  71  and  73  of the present invention hold the majority of the preferred severed vessels  38  away from the ultrasonic blade  66  and that a portion of welded tissue is in contact with the ultrasonic blade  66 . A large portion of the welded tissue length “ω” is formed outside of the angular compression zone β by lateral thermal spread. This portion of welded tissue is laterally spaced away from the ultrasonic blade  66  and is designated as length ω′. Preferred severed vessels  38  will remain clamped between the clamping surface  68   a  and the first and second support surfaces  71 , 73  until the clamp arm  67   a  is opened. It should be noted that the end effector  65  of the preferred invention compresses a laterally wider portion of tissue than the prior art end effector  65   a  and when energy is applied to this compressed tissue, produces a laterally longer tissue weld. This is shown by the wielded length ω′ of the present invention (FIG. 10) which is longer than the welded length “d” of the prior art invention (FIG. 6).  
     [0049] The first and second support beams  70 , 72  are preferably formed as an extension of the metallic outer sheath  63 . It is also possible to construct first and second support beams  70 , as a secondary piece or pieces that are fixably attached to the metallic outer sheath  63  (not shown). Forming the first and second support beams  70 , 72  from at least one secondary piece offers additional flexibility to the preferred instrument. If desired, first and second support beams  70 , 72  can be constructed from a thermally conducting material for the purpose of conducting heat away from the clamped tissue. This limits the flow of heat into the compressed tissue (from lateral thermal spread) and provides precise control of the lateral length of the tissue weld. A wide variety of thermally conducting materials are available such as stainless steel, iron, aluminum, copper, magnesium or any other thermally conductive material.  
     [0050] If desired, a thermally resistive material can be used in the construction of the first and second support beams  70 , 72 . The thermally resistive material confines or channels the flow of heat (from lateral thermal spread) into the tissue compressed between the thermally resistive first and second support beams  70 , 72  and the clamping surface  68   a . This channeling effect effectively maximizes the length of the tissue weld by exposing the maximum amount of compressed tissue to lateral thermal spread. First and second support beams  70 , 72  can be formed of thermally resistive materials such as thermoform or thermoset plastics, carbon-carbon or coated with thermally resistive materials such as ceramics.  
     [0051] Turning now to FIGS.  11 - 15 , another embodiment is shown, along with its method of use. In this alternate embodiment, first and second support beams  70 , 72  and first and second support surfaces  71 , 73  are spaced away from and angled at a support surface angle “θ” relative to a longitudinal axis “L” of the ultrasonic blade  66 . FIG. 11 shows an isometric view of the end effector  65   b  with the clamp arm  67   a  in a fully open position. The first and second support surfaces  71 , 73  are shown angled upwards at the support surface angle “θ” relative to a longitudinal axis of the ultrasonic blade  66 . A horizontal plane “P” is provided extending laterally away from the longitudinal axis of the ultrasonic blade  66  and support surface angle “θ” is measured between plane “P” and the first support surface  71 . In this embodiment of FIG. 2, the first and second support beams  70 , 72  are a cantilever spring formed from a resilient material such as but not limited to stainless steel, and are designed to deflect downward as the clamp arm  67   a  closes. The additional deflection increases the clamping force on tissue such as vessel  35  (FIG. 14). The support surface angle “θ” may be between 3 degrees and 60 degrees and preferably is 10 degrees.  
     [0052]FIGS. 12 and 13 show the clamp arm  67   a  moved from the first open position of FIG. 11 to a second partially closed position to compress tissue. With the clamp arm  67   a  in the second position, it is possible to clamp tissue in three different locations within the end effector  65   b . In all three cases, tissue is clamped against the clamping surface  68   a  and first and second tissue support surfaces  71  and  73 , but in one of the locations, tissue is clamped spaced away from the ultrasonic blade  66 . Thus, the end effector  65   b  of this embodiment has the ability to clamp tissue independently from the ultrasonic blade. In all cases, tissue must be clamped against the ultrasonic blade  66  to coagulate tissue. These three locations will now be described.  
     [0053] In the first location, herein designated a tissue location “δ”, tissue is located proximally within the end effector  65  and is clamped between the first and second support surfaces  71 , 73 , the ultrasonic blade  66 , and clamping surface  68   a . The tissue is held (at a support surface angle θ) against the ultrasonic blade  66 . Actuation of the surgical instrument  23  will coagulate this tissue similarly to that described above in the preferred invention description.  
     [0054] A second location, designated a tissue location “ε”, has tissue compressed between the clamping surface  68   a , the first and second support surfaces  71 , 73  and the ultrasonic blade  66 . The proximal end of the tissue is in contact with the ultrasonic blade  66  and the distal end of the tissue is suspended above the ultrasonic blade  66 . At tissue location “ε”, actuation of the surgical instrument  23  will coagulate and cut the tissue in a proximal to distal manner as the operator closes the clamp arm  67   a  against an active ultrasonic blade  66 .  
     [0055] In the third location, designated as a tissue location “φ”, the tissue or vessel  35  is compressed between the clamping surface  68   a  and the first and second support surfaces  71 , 73 . At tissue location “φ”, the tissue portion is held suspended above the ultrasonic blade  66 . An end view of clamped tissue is shown in FIG. 13 to better show how the vessel  35  is held suspended above the ultrasonic blade  66 . Pressure streamlines  36  are provided to show areas of clamping pressure. From this position, the vessel  35  can be brought down upon an active or an un-active ultrasonic blade  66  when the clamp arm  67   a  is moved to the fully closed position (FIGS. 2 and 14).  
     [0056] As the clamp arm  67   a  moves to the fully closed position of FIG. 14, first and second support beams  70 , 72  deflect downward to the horizontal position as shown. In FIG. 14, vessel  35  in is held against ultrasonic blade  66  prior to the application of ultrasonic energy. The additional deflection of the first and second support beams  70 , 72  increases the pressure on the vessel  35  over the previously described instrument of FIGS. 2 and 7- 10  which compresses tissue to a height of “h” (see FIGS. 9 and 14). This additional deflection compresses the portion of the vessel  35  clamped between the clamping surface  68  and the first and second support surface  71 , 73  an additional amount to a second clamped height “h′”. The reader is advised to note that the second clamped tissue height “h′” of FIG. 14 is less than the first clamped height “h” of FIG. 9 due to the increased clamping forces exerted by the first and second support beams  70 , 72 . This increase in clamping force results in a slight bulging of the vessel  35  between each of the first and second support beams  70 , 72  and the ultrasonic blade  66 . The additional compression from the angled support beams  71 ,  73  bulges the tissue inwardly towards the ultrasonic blade  66  and creates an angular compression zone “γ” that is slightly wider than the angular compression zone “β” as shown in FIGS. 8 and 9. The application of ultrasonic energy to the compressed vessel  35  welds and cuts the vessel  35  producing the alternate severed vessels  39  as shown in FIG. 15. The coagulated tissue  37  on the ends of the severed vessels  35   a  forms a welded tissue length “y”. The cut ends of the alternate severed vessels  39  are shown as dashed lines in FIG. 14. The continued application of ultrasonic energy will cut the vessel  35 , and a first portion of the vessel is in contact with the ultrasonic blade  66  and a second portion compressed against the tissue support surfaces  71 , 73 . The continued application of ultrasonic energy to the clamped vessel  35  coagulates and severs the vessel  35  by coagulating and atomizing or pluming the tissue.  
     [0057] While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. Accordingly, it is intended that the invention be limited only by the spirit and scope of the appended claims.