Abstract:
The present invention provides for a sutureless clip for use in temporarily pacing the human heart. The clip comprises a generally V-shaped clip having on at least one outer surface thereof with one or more channels for the attachment of pacing electrodes, the inner surfaces of the clip optimally being textured to provide a greater contact surface area. The clip is readily deformable to allow for its attachment to the outer surface of the heart.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to an apparatus for placing electrodes on the heart. More particularly, the invention relates to a sutureless clip for attaching electrodes to the heart for temporary pacing and a method of doing so.  
         BACKGROUND OF THE INVENTION  
         [0002]    In the course of many surgical procedures involving the heart, a standard procedure in most cardiac centers is, prior to closing the sternum, to connect a temporary pacing device to the heart. This is usually done with a wire which is connected to an external cardiac pacer. The pacing may be accomplished in either a unipolar or bipolar fashion.  
           [0003]    Typically, pacing electrode leads are sutured onto the right atrium or ventricular wall. However, problems may arise in pacing and sensing. In many instances there will be bleeding while the leads are placed or removed, which creates an unnecessary complication. Also, the wall may be thin and friable, which adds further complications.  
           [0004]    Electrode resistance is a function of the electrode radius such that a higher resistance is provided by a smaller electrode. Stimulation threshold is a function of current density generated at the electrode. The smaller the radius of the electrode, the greater the current density. The resistance at the electrode myocardia interface is higher with smaller electrodes. In contrast, sensing impedance and electrode polarization are decreased with electrodes of larger surface area. These sensing considerations favor the use of a large area electrode.  
           [0005]    The ideal pacing lead would have an electrode with a small radius, which serves to increase current density, and a large surface area, which serves to improve sensing ability. It has been found that the best way to provide for these conflicting advantages is to provide an electrode with a small radius and a lead having a complex surface structure that provides a large surface area. Prior pacing leads used electrodes with a polished metal surface. The use of electrodes with a textured surface has resulted in a dramatic increase in the surface area of the electrode without an increase in its radius.  
         OBJECTS OF THE INVENTION  
         [0006]    It is an object of the invention to provide a sutureless electrode clip.  
           [0007]    It is also an object of the invention to provide a sutureless electrode clip that quickly and safely fastens to the heart to provide temporary pacing.  
           [0008]    It is a further object of the invention to provide a sutureless electrode clip that can be quickly and safely fastened to the heart and wherein the electrodes can be easily removed or released after use.  
           [0009]    It is a yet further object of the invention to provide a sutureless clip for attachment to the heart when the electrode lead is intended to take advantage of the increased current density resulting from a small radius of the electrode and decreased sensing impedance that is characteristic of a larger surface area.  
           [0010]    These are other objects of the invention will be more apparent from the discussion below.  
         SUMMARY OF THE INVENTION  
         [0011]    In accordance with the present invention a sutureless clip for use in connecting a temporary heart pacing device to the epicardium of a human heart is provided, wherein one or more electrodes can be releasably engaged by a clip. The clip consists of a generally V-shaped clip having on at least one outer surface thereof one or more channels or receivers for receiving one or more pacing electrodes to be connected through the skin to a pulse generator, which may be uni- or bipolar. The outer and/or lateral surfaces of the clip have an insulated coating, and, when there are two channels on a surface, there may be an insulating barrier between the two channels. One or more of the non-insulated inner surfaces of the clip are preferably textured to provide a greater contact surface area, and the clip is readily deformable to allow for its attachment to the surface of the heart. The clip is preferably applied with a grasping applicator forceps which is provided with a set of jaws to accommodate the clip geometry, so that the user may insert a clip into the forceps and, by applying pressure to the grasping end of the forceps, deform the clip in a desired position on the surface of the heart.  
           [0012]    The clip and grasping forceps system of the present invention has the advantage that no suturing of the pacing leads to the heart is required. This eliminates the disadvantages associated with bleeding which occur when such suturing is carried out and the problems normally encountered when the walls of the heart have become thin and friable.  
           [0013]    Furthermore, the clip of the present invention provides a better overall pacing lead connection due to the very large relative contact area provided by the textured inner surfaces of the clip which come in contact with the heart tissue. This contrasts with the usual wire that is used to penetrate the atrium, leaving a very small contact point with the heart.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    [0014]FIGS. 1 and 1A are each a perspective view of an embodiment of the invention showing the essential components;  
         [0015]    [0015]FIG. 2 is a right side view of the clip of FIG. 1; and  
         [0016]    [0016]FIG. 3 is a plan view of the grasping forceps used to place the clip of FIG. 1, showing one clip in place prior to placement on the heart. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0017]    In FIG. 1 a perspective view of a sutureless clip of the present invention is depicted showing the V-shaped clip  10 , having two pivoting or deformable members or jaws  12 , which are deformable about an axis  14 . The outer surface  16  of at least one of the jaws  12  is provided with at least one channel  18  intended to receive and engage a pacer electrode  20 . At least one inner surface  22  of each jaw  12  is preferably textured to increase the contact surface area.  
         [0018]    A lateral view of clip  10  of FIG. 1 is shown in FIG. 2, depicting outer surfaces  16  of each jaw  12 , inner textured surfaces  22 , pacer electrodes  20 , and axis of deformation rotation  14 .  
         [0019]    The outer surfaces  16 , lateral surfaces  24 , and, optionally, end surfaces  26  have an insulated layer  28 . When an outer surface layer  16  has two channels  18 , jaws  12  will also comprise an insulating barrier  30 . Alternatively, clip  10  may comprise only a single channel  18  to hold one electrode  20 , whereupon no insulating barrier  30  would be necessary.  
         [0020]    In a further embodiment, as shown in FIG. 1A, one outer surface  52  of V-shaped clip  54  could comprise one channel  56  for electrode  58  with insulation  60 , and the other outer surface  62  could comprise a second channel  64  for electrode  66  with insulator  68 . Channels  56  and  64  would preferably be arranged so that electrodes  58  and  66  would not interfere with one another. Jaws  70  and  72  of clip  54  would preferably be insulated from one another by insulation member  74 . Preferably outer surfaces  52  and  62 , lateral surfaces  76  and  78 , and optionally end surfaces  80  and  82 , have insulated layers  84  and  86 .  
         [0021]    Insulated layers  28 ,  74 ,  84 , and  86  each comprise a physiologically acceptable electrical insulating material, such as a silicone polymer or copolymer. Barrier  30  can be comprised of a physiologically acceptable electrical insulation similar to, or different from, the material of insulating layers  28 ,  74 ,  84 , and  86 . The portion of the electrodes proximal to the V-shaped clip will preferably have a typical electrical insulation  32 ,  60 , or  68 . Insulation  32 ,  60 , or  68  can comprise any of the known, physiologically acceptable polymers or copolymers suitable for this purpose.  
         [0022]    In the embodiments of the invention shown in FIGS. 1, 1A, and  2 , electrodes or electrode members are received in channels, preferably releasably. More particularly, the distal ends of an electrode would be engagingly received in a channel to provide pacing during a temporary pacing period. At the appropriate time the electrode could be disengaged from the clip, for example, by pressure applied in the proximal direction. Alternatively, the distal end of the electrode or electrode member, such as a needle-like structure, could comprise a breakable structure so that after the pacing period, the electrode could be twisted or pulled to leave the electrode distal end safely in the clip and withdraw the remainder of the electrode.  
         [0023]    Consistent with the scope of the invention the deformable members could have means other than a channel to receive an electrode. For example, each pivoting member or jaw could comprise an opening of suitable size and depth to engagingly receive an electrode or electrode member  
         [0024]    [0024]FIG. 3 is a lateral view of a long-handled, grasping forceps  40  used to place clip  10 . Forceps  40  has a pair of elongated grasping handles  42  which are rotatable about an axis or point  44 . The grasping ends  46  of forceps  40  are provided with retainer means  48  with which to secure the ends of the clip  10  within the jaws  46 , in the open position. Forceps  40  are also provided with a spring means  50 , which maintains forceps  40  in the open position until force is applied to forceps handles  42  to position clip  10  and deform it in the desired position on the epicardium.  
         [0025]    The V-shaped clip of the present invention may be fabricated out of any of a number of physiologically acceptable, suitable materials as will be known to one skilled in this art. It has been found that the following materials are particularly useful for fabrication of the V-shaped clip of the invention: platinum, iridium, Elgiloy, pyrolitic, carbon coating, ipanium, graphite platinum and iridium oxide.  
         [0026]    The grasping forceps used to place the V-shaped clip of the present invention may be fabricated out of a number of known materials as will be familiar to one skilled in the art of surgical instruments. Typically the grasping forceps of the present invention will be fabricated out of stainless steel or some other metal alloy which have been found to be suitable for surgical applications.  
         [0027]    The method of the present invention for attachment of pacing leads to the human heart muscle consists of:  
         [0028]    inserting a V-shaped clip into the retaining end of the grasping forceps;  
         [0029]    placing the clip in intimate proximity to the desired heart tissue;  
         [0030]    deforming the clip by applying suitable force to the forceps handles, thus attaching the clip to the atrial or ventricular heart muscle tissue; and  
         [0031]    attaching the pacer electrodes to each of the channels provided in the outer surface of the V-shaped clip.  
         [0032]    Optionally the electrodes may be inserted into the channels prior to attachment.  
         [0033]    The method of the present invention is safe both in placement and subsequent removal. It is quick, functional and easy to carry out, and no suturing to the atrium is required. Once the V-shaped clip is placed on the right atrium, unipolar or bipolar pacing wires may be attached and then removed quickly and safely.  
         [0034]    The clips of the invention are intended for temporary pacing. At the appropriate time after the clips are inserted and the wires or electrodes are attached, which could be from about 2 or 3 days later or even weeks or months later, the wires or electrodes will be removed or severed. The clips remain in place in the patient.  
         [0035]    It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the constructions set forth without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.  
         [0036]    It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.