Abstract:
An instrument for exerting an end of a vessel over an end of a tubular workpiece. The instrument has a body having an axial bore, and a mandrel mounted within the axial bore and partially extending from the distal end of the axial bore. The mandrel is made from a sheet of spring-like material rolled into a conical shape. The distal end of the mandrel is insertable into the lumen of the vessel. A plunger substantially contained within the axial bore and axially moveable, extends into the proximal end of the mandrel and presses against an inner surface of the mandrel when the plunger is moved from a retracted position to an extended position, thereby causing the distal end of the mandrel to expand radially and the proximal end of the mandrel to contract radially. An optional spring mounted to the body provides a biasing force to move the plunger to the retracted position and to allow the mandrel to return to the conical shape.

Description:
FIELD OF THE INVENTION 
     The field of art to which this invention relates is medical devices, more specifically, medical devices and surgical procedures for performing anastomosis of hollow organs such as blood vessels. 
     BACKGROUND OF THE INVENTION 
     Anastomosis surgical procedures are common in the field of cardiac surgery. 
     These procedures are conventionally used for repairing a damaged or diseased blood vessel. In a typical anastomosis procedure, a surgeon joins a first blood vessel to a second blood vessel and creates a passageway between the two blood vessels to provide for the communication of blood flow. For this kind of anastomosis, the surgeon typically uses specialized grasping tools to manipulate a tiny, curved needle attached to an extremely fine surgical filament (under 0.001 inch diameter) to suture the vessels together. The vessels may be joined end-to-end, end-to-side, or side-to-side. To facilitate healing of the joined vessels, the prevailing standard of care requires that the surgeon suture the inside surfaces of the first and second vessels together, intima to intima. The surgeon must take great care not to damage the intima of each vessel so that endothelial cells may form over the anastomosis without the formation of thrombus or other complications, thus improving the likelihood of a long term patency of the vessels. For life-saving procedures such as coronary artery bypass graft surgery (CABG), this is especially important. When performing a distal anastomosis in a conventional CABG procedure, the surgeon typically sutures an end-to-side anastomosis of a distal end of a graft vessel (such as a segment of saphenous vein harvested from the patient) to a side of a target vessel (the stenosed coronary artery). For a proximal anastomosis in a conventional CABG procedure, the surgeon sutures a proximal end of the graft vessel to the side of the aorta. 
     As this field of art has progressed over the last several years, new anastomotic methods have been developed and introduced in attempts to replace the suturing technique briefly described above. Many of these methods incorporate novel fasteners and fastener appliers. The requirement, however, to maintain intima-to-intima contact of the joined vessels remains just as important with these approaches. In fact it is often necessary, prior to joining the vessels, for the surgeon to evert (i.e., turn inside out) the end of at least one of the vessels over the end of a member such as a tube, ferrule, or bushing, etc., which is a component of the fastener or fastener applier. This exposes the intima of that vessel for presentation to the intima of the other vessel prior to fastening the vessels. 
     Although it is possible to evert larger vessels (over 5 mm in diameter) using standard forceps and graspers available in the operating room, such methods are slow and may result in excessive damage to the vessel everted. And, often the surgeon requires assistance in performing the eversion procedure. Furthermore, vessels smaller than 5 mm are very difficult, if not impossible, to evert using such methods. 
     There are several requirements for an effective vessel eversion device. As noted earlier, for proper healing, it is important not to injure the intima of either vessel during the eversion procedure. The eversion device also must be easy for the surgeon to use without assistance and require only a few steps to operate. The eversion device must be useful for a wide range of blood vessel sizes, particularly small vessels, e.g., having a diameter of about 2-3 mm or less. In addition, it is desirable for the eversion device to be useful on one end of a vessel, when the opposite end is already attached to the patient (e.g., at the distal anastomosis of a patient undergoing a CABG procedure). The eversion device should also allow for the proper length of everted tissue, depending on the requirements of the anastomosis device or method to be used. Finally, it is desirable that the eversion device is low cost and yet operates reliably. 
     Accordingly, there is a need in this art for novel devices and methods for engaging and everting the end of a blood vessel (or other tubular body organ), which can be used in a quick and effective manner without causing trauma to the vessel or the intima of the vessel (or tubular body organ). 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide novel eversion devices which are easy for the surgeon to use without assistance, and which efficiently and effectively engage blood vessels and evert the ends of blood vessels, including blood vessels having small or fine diameters. 
     A further object of the present invention is to provide novel eversion devices which engage blood vessels and evert the ends of blood vessels without causing trauma to the blood vessel or the intima of the blood vessels. 
     It is yet another object of the present invention to provide novel methods of engaging and everting blood vessels quickly and efficiently, while preventing or minimizing damage to the blood vessels and the intimas of the blood vessels. 
     It is still yet a further object of the present invention to provide a novel vessel eversion device and procedure for everting one end of a vessel having the other end already attached to another vessel. 
     Accordingly, an eversion instrument for everting an end of a vessel is disclosed. 
     The instrument has a hollow frame having a distal end, a proximal end, and an axial bore. The axial bore has a distal section and a proximal section. A mandrel member is mounted within the distal section of the axial bore. The mandrel has a proximal end and a distal end, the distal end partially extending from the distal end of the hollow frame. The mandrel member is made from a sheet of spring-like material rolled into a substantially conical shape, having a proximal end, a distal end, an inner surface, and an inner lumen, wherein the distal end of said mandrel is insertable into the lumen of a vessel. And, a plunger member is slidably mounted in the axial bore and axially moveable therein. The plunger member has a distal end and a proximal end. The plunger is moveable in the lumen of the mandrel member, and the distal end of the plunger member engages the inner surface of the mandrel member when the plunger is manually moved from a retracted position to an extended position, thereby causing the distal end of the mandrel member to expand radially outward and the proximal end of the mandrel to contract radially inward. 
     Another aspect of the present invention is the combination of the above-described instrument and a tubular member. The tubular member has a tubular frame with a distal end, a proximal end, an inner lumen and an outer surface and an inner surface. 
     Still yet another aspect of the present invention is a method of everting the end of a vessel using the above-described instrument. 
     These and other aspects and advantages of the present invention will become more apparent from the following description and accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view an eversion instrument  10  of the present invention. 
     FIG. 2 is a cross-sectional view of eversion instrument  10  of FIG. 1, illustrating a step of inserting eversion instrument  10  into a vessel portion  102 . 
     FIG. 3 is a cross-sectional view of eversion instrument  10 , illustrating a step of radially expanding vessel portion  102 . 
     FIG. 4 is a cross-sectional view of eversion instrument  10 , illustrating a step of invaginating vessel portion  102 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An eversion instrument  10  of the present invention useful for everting a vessel portion  102  (see FIG. 2) of a vessel  100  over the distal end of a tube  90 , also referred to as a tubular workpiece  90  or a tubular member  90 . Vessel  100  may be a blood vessel, such as a segment of the greater saphenous vein, having a diameter of about 2-8 mm, although other hollow organs may be everted using eversion instrument  10 . Tube  90  contains or holds vessel  100  and is representative of numerous kinds of bushings, ferrules, tubes, and specialized devices having an approximately cylindrical shape with an axial bore through it. The tube  90  is also seen to have an outer surface  91 . Vessel  100  is inserted into an axial bore  92  of tube so that distal vessel portion  102  of vessel  100  extends beyond a distal tube end  98  of tube  90 . The length of vessel portion  102  extending out from axial bore  92  beyond distal tube end  98  is sufficient to effectively provide for the desired length of eversion, and is preferably in the range of 5-15 mm. An operator of eversion instrument  10 , an assistant, or a mechanical holding device holds tube  90  as the operator uses eversion instrument  10  to evert vessel portion  102  onto the section of tube surface  91  of distal end  98  of tube  90 . 
     As seen in FIGS. 1 and 2, eversion instrument  10  comprises a cylindrical frame member  20  having a distal end  22 , a proximal end  24 , an inner surface  21  surrounding an axial bore  26  therethrough, and an outer surface  29 . If desired frame member  20  may have other geometric cross-sections including oval, square, triangular, rectangular, polygonal, combinations thereof and the like. Eversion instrument  10  further comprises a piston  40  slideably mounted in axial bore  26  of cylinder  20 . Piston  40  has a rounded, distal end  42 , a proximal end  44 , and a ring  46  located approximately halfway between distal end  42  and proximal end  44 . A spring  70 , preferably a stainless steel, coiled wire, compression spring or equivalent biasing member, mounts loosely over piston  40  and between ring  46  and an internal flange  28  that extends radially inward from inner surface  21  of cylinder  20 , thus providing a biasing force to piston  40  in the proximal (right) direction. 
     Eversion instrument  10  also has a conical element  80  having a distal end  82  and a proximal end  84 , an inner lumen  85  and an outer surface  87  mounted in the distal section of the axial bore  26 . Distal end  82  is seen to extend out from distal end  22  of frame  20 . When unconstrained, conical element  80  is normally in a cone-like configuration with distal end  82  having a much smaller diameter (in the range of 1-3 mm) than the diameter of proximal end  84 . Conical element  80  may be made, for example, from a sheet of stiff but resilient material such as approximately 0.25 mm thick polycarbonate (PC) sheet, which has been rolled into a funnel shape, heat set for a few seconds at a temperature just high enough to soften the material, and then permitted to cool while still constrained in the funnel shape. Conical element  80  may be made from sheets of any one of a number of polymeric or metallic materials of varying thicknesses, including approximately 0.25 mm thick cellulose acetate propionate (CAP), and approximately 0.10 mm thick stainless steel foil (shimstock). Preferably, however, conical element  80  is made of a transparent material such as PC or CAP so that vessel portion  102  is visible during each step of the operational sequence for using eversion instrument  10 . 
     FIG. 2 depicts a step of the manual operational sequence for everting vessel  100 . The operator holds cylinder  20 , preferably between the thumb and second finger, while the index finger is positioned on proximal end  44  of piston  40 . Distal end  82  of conical element  80 , being smaller in diameter than the opening in vessel portion  102 , is easily inserted into lumen  105  of the extending distal section  102  of vessel  100 . The operator or an assistant may use fingertips or another surgical instrument such as a probe or a forceps, to “milk” or urge vessel portion  102  onto surface  87  of conical element  80 . 
     FIG. 3 depicts eversion instrument  10  being used in a step of the operational sequence of radially expanding vessel portion  102  of vessel  100 . The operator pushes on proximal end  44  of piston  40  while holding cylinder  20  approximately stationary relative to tube  90 . Distal end  42  of piston  40  advances distally (left) in lumen  85  to cause conical element  80  to change to a substantially cylindrical configuration as shown. Distal end  82  and proximal end  84  of conical element  80  become approximately equal in diameter, and larger than the diameter of tube  90 . The inner lumen  105  in the distal section  102  of vessel  100  similarly has a diameter larger than the outside diameter of distal end  98  of tube  90 . Spring  70  compresses, thus increasing the biasing force on piston  40  in the proximal (right) direction. 
     FIG. 4 depicts eversion instrument  10  being used in a step of the operational sequence of invaginating vessel portion  102  over tube  90  onto surface  91  of distal end  98 . The operator moves cylinder  20  in the distal direction (left) so that distal end  82  of conical element  80  passes over tube  90 , thus everting vessel portion  102  onto tube  90 . The operator releases piston  40 , allowing piston  44  to move proximally (to the right) as spring  70  expands and distal end  42  retracts from vessel  100 . Eversion instrument  10  may then be slid off of the everted vessel  100  and reset for another use by allowing piston  40  to move further in the proximal direction so that conical element  80  resumes a conical configuration as shown in FIG.  2 . 
     When conical element  80  is in the cylindrical configuration as shown in FIG. 4, a circumferential edge  86  on distal end  82  of conical element  80  is approximately square, that is the imaginary plane defined by circumferential edge  86  is approximately perpendicular to the longitudinal axis of eversion instrument  10 . As a consequence, circumferential edge  86  provides a continuous edge for pushing against vessel portion  102  during the step of invaginating. By distributing an everting force circumferentially as in the present invention, less trauma to the vessel occurs than with multi-fingered devices, thus reducing the possibility of injury to the vessel and later complications. Using conical element  80  for the initial flaring or radial stretching of vessel portion  102  also facilitates an even distribution of radial tensile (hoop) stress in the vessel walls, substantially preventing the creation of localized regions of high stress. In addition, vessel portion  102  only needs to be flared or radially expanded to a diameter to fit over tube  90 , substantially eliminating overstretching. 
     Eversion instrument  10  as described for the specific embodiment shown in FIGS. 1-6 is constructed of low cost materials and preferably is supplied to the end user as a sterilized unit intended for single patient use. Re-sterilizable embodiments of eversion instrument  10  intended for multi-patient use will become apparent to those skilled in the art. 
     The following example is illustrative of the principles and practice of the present invention although not limited thereto. 
     EXAMPLE 
     A patient undergoing cardiac coronary artery bypass graft (CABG) surgery is prepared for surgery and anesthetized in a conventional manner in accordance with the prevailing medical standards. The patient&#39;s chest is opened in a conventional manner by cutting through the sternum and expanding the rib cage with a conventional surgical retractor instrument. The patient&#39;s heart is accessed in a conventional manner and the patient is connected to a pulmonary bypass machine and the heart is stopped. A section of the patient&#39;s saphenous vein, which has already been harvested by this time, is prepared for use as a graft vessel. The graft vessel end that is to be attached to the aorta for the proximal anastomosis is everted using an eversion instrument of the present invention as already described in the detailed description and shown in FIGS. 2-4. In FIG. 4, an end  102  of vessel  100  is shown everted over distal end  98  of tube  90 . One embodiment of tube  90  is disclosed in published patent application WO0056228, “Low Profile Anastomosis Connector”, filed on Mar. 20, 2000, assigned to By-Pass, Inc., and which is hereby incorporated herein by reference. As described in WO0056228, a metallic anastomosis connector comprising a plurality of ring segments is used to fasten the graft vessel to another vessel such as the aorta. The distal end of the graft vessel is then anastomotically attached to a coronary artery on the heart using a conventional hand suturing method. Additional bypasses are performed in the same manner or variations, depending on the patient&#39;s condition and anatomy. The remainder of the CABG procedure is conducted in a conventional manner and includes the steps of inspecting and repairing the grafts for leaks, checking blood flow, removing the patient from the pulmonary bypass machine, and closing the surgical incision. 
     The eversion instruments and eversion methods of the present invention have many advantages. The present invention is less traumatic to the intima of the vessel during the eversion procedure than conventional surgical graspers and the like. The present invention is easy for the surgeon to use without assistance and requires only a few steps to operate. The present invention is useful for a wide range of blood vessel sizes, particularly small vessels, e.g., having a diameter of about 2-3 mm or less. In addition, the present invention is useful on one end of a vessel, when the opposite end is already attached to the patient (e.g., at the distal anastomosis of a patient undergoing a CABG procedure). The present invention also allows for the proper length of everted tissue over the tube, bushing, or the like, depending on the requirements of the anastomosis device or method being used. Finally, the present invention may be manufactured inexpensively. 
     Accordingly, there is a need in this art for novel devices and methods for engaging and everting the end of a blood vessel (or other tubular body organ) over a member such as a tube, ferrule, bushing, or the like which can be used in a quick and effective manner without causing trauma to the vessel or the intima of the vessel (or tubular body organ). 
     Although this invention has been shown and described with respect to detailed embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail thereof may be made without departing from the spirit and scope of the claimed invention.