Abstract:
In some embodiments, without limitation, the invention comprises an apparatus for cutting an endocardial lead within a patient. The apparatus comprises a generally flexible tubular member having a proximal end and distal end. At least one blade or cutting surface is affixed to the distal end of the tubular member. The apparatus optionally includes an adjustment mechanism adapted to adjust the blade or cutting surface between an extended position and a retracted position. The blade or cutting surface engages the endocardial lead to cut the lead. Various embodiments include a v-shaped groove defining the cutting surfaces. Other embodiments may comprise a rotatable blade of an inner shaft rotating within the tubular member and cutting the lead received within the v-shaped groove, and blades or cutting surfaces functioning like guillotines or scissors retracting into a distal end of the tubular member.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates generally to an endocardial lead cutting apparatus and, more particularly, to an apparatus including at least one blade or cutting surface for cutting endocardial leads within a patient. 
       BACKGROUND OF THE INVENTION 
       [0002]    In the past, various types of endocardial leads and electrodes have been introduced into different chambers of a patient&#39;s heart, including the right ventrical, right atrial appendage, and atrium as well as the coronary sinus. These flexible leads usually are composed of an insulator sleeve that contains an implanted helical coil conductor that is attached to an electrode tip. This electrode is placed in contact with myocardial tissue by passage through a venous access, often the subclavian vein or one of its tributories, which leads to the endocardial surface of the heart chambers. The tip with the electrode contact is held in place by trabeculations of myocardial tissue. 
         [0003]    The tips of many available leads include flexible tines, wedges, or finger-like projections which extend radially outward and usually are molded from and integral with the insulating sheath of the lead. These tines or protrusions allow surrounding growth of tissue in chronically implanted leads to fix the electrode tip in position in the heart and prevent dislodgement of the tip during the life of the lead. In “acute placement” of the electrode or lead tip, a blood clot forms about the flanges or tines (due to enzymes released as a result of irritation of the trabeculations of myocardial tissue by the presence of the electrode tip) until scar tissue eventually forms, usually in three to six months. The tines or wedges or finger-like projections allow better containment by the myocardial trabeculations of muscle tissue and prevent early dislodgement of the lead tip. 
         [0004]    Although the state of the art in implemented pulse generator or pacemaker technology and endocardial lead technology has advanced considerably, endocardial leads nevertheless occasionally fail, due to a variety of reasons, including breakage of a lead, insulation breaks, breakage of the inner helical coil conductor and an increase in electrode resistance. Furthermore, in some instances, it may be desirable to electronically stimulate different portions of the heart than are presently being stimulated with the leads already implanted. There are a considerable number of patients who have one or more, and sometimes as many as four or five unused leads in their veins and heart. 
         [0005]    Although it obviously would be desirable to easily remove such unused leads, in the past surgeons usually have avoided attempts to remove inoperative leads because the risk of removing them exceeded the risk of leaving them in. The risks of leaving unused myocardial leads in the heart and venous path include increased likelihood that an old lead may facilitate infection, which in turn may necessitate removal of the lead to prevent continued bacteremia and abcess formation. Furthermore, there is an increased likelihood of the formation of blood clots in the atrial chamber about entangled leads. Such clots may embolize to the lung and produce severe complications and even fatality. Furthermore, the presence of unused leads in the venous pathway and inside the heart can cause considerable difficulty in the positioning and attachment of new endocardial leads in the heart. 
         [0006]    Removal of an inoperative lead sometimes can be accomplished by applying traction and rotation to the outer free end of the lead, for example, if done prior to fixation of the lead tip in the trabeculations of myocardial tissue by scar tissue formation or large clot development. Even then, it is possible that a clot has formed so the removal of the leads causes various sized emboli to pass to the lungs, producing severe complications. 
         [0007]    In cases where the lead tip has become attached by scar tissue to the myocardial wall, removal of the lead always has presented major problems and risks. Porous lead tips that are sometimes used may have an ingrowth of scar tissue attaching them to the myocardial wall. Sufficient traction on such leads in a removal attempt could cause disruption of the myocardial wall prior to release of the embedded lead tip. The tines or flanges of other types of leads that are not tightly scarred to the myocardial wall present similar risks. Even if screw-in tip electrodes are used, wherein the tips theoretically can be unscrewed from the myocardial wall, unscrewing of such tips may be prevented by a channel of scar tissue and endothelium that surrounds the outer surface of the lead along the venous pathway. Such “channel scar” tissue prevents withdrawal because of tight encasement of the lead. Continual strong pulling or twisting of the outer free end of the lead could cause rupture of the atrial wall or the ventricular wall if there is such tight circumferential encasement of adherent channel scar tissue in the venous path. Such tight encasement by scar tissue in the venous pathway and in the trabeculations of the myocardial wall typically occurs within six months to a year of the initial placement of the lead. 
         [0008]    The risks of removing the lead by such traction and rotation of the lead are so high that, if it becomes imperative that the lead be removed (as in the case of infection), most surgeons have elected to open the patient&#39;s chest and surgically remove the lead rather than attempt removal by applying traction and rotation thereto. 
         [0009]    Clearly, there is a need for an apparatus for extracting endocardial leads from a patient&#39;s heart with minimal risk to the patient. 
       SUMMARY OF THE INVENTION 
       [0010]    To address these and other drawbacks, in some embodiments, without limitation, the present invention comprises an apparatus for cutting the lead as near as possible to an endocardial lead&#39;s embedded electrode. 
         [0011]    Specifically, the present invention comprises an apparatus having a generally flexible tubular member having a proximal end and distal end. At least one blade or cutting surface is affixed to the distal end of the tubular member. In some embodiments, the apparatus includes an adjustment mechanism adapted to adjust the blade or cutting surface between an extended position and a retracted position. 
         [0012]    Other aspects of the invention will be apparent to those skilled in the art after reviewing the drawings and the detailed description below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
           [0014]      FIG. 1  illustrates a perspective view of an endocardial lead cutting apparatus of a first embodiment of the present invention; 
           [0015]      FIG. 2  illustrates a perspective view of an endocardial lead cutting apparatus of a second embodiment of the present invention; 
           [0016]      FIG. 3  illustrates an enlarged perspective view of a distal end of an outer tubular member of the second embodiment of the present invention; 
           [0017]      FIG. 4  illustrates an enlarged perspective view of a distal end of an inner shaft of the second embodiment of the present invention; 
           [0018]      FIG. 5A-5C  illustrate end views of the endocardial lead cutting apparatus of the second embodiment of the present invention having the inner shaft rotating to cut the lead; 
           [0019]      FIG. 6  illustrates a cross-sectional view of an endocardial lead cutting apparatus of a third embodiment of the present invention; 
           [0020]      FIG. 7  illustrates an enlarged cross-sectional view of a distal end of the endocardial lead cutting apparatus of the third embodiment of the present invention; 
           [0021]      FIG. 8  illustrates a perspective view of an endocardial lead cutting apparatus of a fourth embodiment of the present invention; 
           [0022]      FIG. 9  illustrates a perspective view of an endocardial lead cutting apparatus of a fifth embodiment of the present invention; 
           [0023]      FIG. 10  illustrates a perspective view of an endocardial lead cutting apparatus of a sixth embodiment of the present invention; and 
           [0024]      FIGS. 11A-11C  illustrate enlarged perspective views of the distal end of the endocardial lead cutting apparatus of the sixth embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    Referring generally to  FIGS. 1-11  and without limiting the scope of the embodiments of the invention, various embodiments of an apparatus are generally referred to at  10  for cutting an endocardial lead  100 . 
         [0026]    Referring to  FIG. 1 , the apparatus  10  of a first embodiment includes a shaft  12  having a proximal end  14  and a distal tip  16 . The shaft  12  is generally flexible to facilitate movement of the apparatus  10  within the patient. The proximal end  14  of the shaft  12  includes a handle  18  while the distal tip  16  includes at least one cutting surface  20 . 
         [0027]    The at least one cutting surface  20  is defined by a groove  22  at the distal tip  16 . The groove  22  is illustrated as generally v-shaped. Accordingly, as illustrated, the v-shaped groove  22  defines two cutting surfaces  20 . Further, the cutting surfaces  20  are comprised of a generally hardened material, such as carbide and the like. While illustrated as a v-shaped groove  22 , other configurations, such as u-shaped, c-shaped and the like are contemplated by the present invention. 
         [0028]    Optionally, a shroud (not shown) is positioned about the shaft  12  such that a distal end of the shroud extends outwardly of the distal tip  16  of the shaft  12 . The shroud is made of a generally pliable material to prevent damage to tissue of the patient prior to use of the apparatus  10 . 
         [0029]    Further, as an additional optional feature, the apparatus  10  may include a device (not shown) to provide an additional form of energy to cut the endocardial lead. By way of example, the device may be a laser generating device, an ultrasonic device, a vibration device and the like. The exemplary devices would apply radiation, ultrasonic waves or vibrations, respectively, to the lead  100  to assist in cutting the lead  100 . In the example of a laser generating device, an optical fiber (not shown) would be disposed within the shaft  12  to transmit radiation from the proximal end  14  to the distal tip  16 . 
         [0030]    In operation, the first embodiment of apparatus  10  of  FIG. 1  is inserted within a patient&#39;s heart (not shown) and the lead  100  (shown in phantom) is received within the groove  22  at the distal tip  16 . When positioned to receive the lead  100  the pliable shroud is urged away from the distal tip  16  to expose the groove  22  and cutting surfaces  20 . Linear and rotation motion is applied by way of the handle  18  to the shaft  12 . The cutting surfaces  20  of the groove  22  then engages the lead. As additional pressure is applied the cutting surfaces  20  cut the lead and the apparatus  10  is removed from the patient. Optionally, when the lead  100  is received in the groove  22  the additional forms of energy such as radiation, ultrasound or vibration is applied to the lead to assist in cutting the lead  100 . 
         [0031]    A second embodiment of the apparatus  10  is shown in  FIGS. 2-5 . The second embodiment includes an outer tubular member  212  having a proximal end  214  and a distal end  216 . The outer tubular member  212  is generally flexible to facilitate movement of the apparatus  10  within the patient. The distal end  216  includes a groove  220  for receiving the lead  100 . As illustrated, the groove  220  is generally v-shaped for receiving the lead  100 ; however, other configurations are also contemplated by the present invention. 
         [0032]    An inner shaft  222  is received within the outer tubular member  212 . The inner shaft  222  includes a proximal end  224  and a distal end  226 . Further, the inner shaft  222  is generally flexible and includes a handle  228  disposed at the proximal end  224 . Positioned at the distal end  226  of the inner shaft is a blade  230 . The blade  230  and the inner shaft  222  is made from a generally hardened material, such as carbide and the like, and rotates within the outer tubular member  212  to cut the lead  100  received within the groove  220  of the outer tubular member  212 . The inner shaft  222  and blade  230  are rotatable in either direction. 
         [0033]    Further, as described with respect to the first embodiment of  FIG. 1 , the apparatus  10  may include a shroud (not shown). The shroud is positioned about the outer tubular member  212  such that a distal end of the shroud extends outwardly of the distal end  216  of the outer tubular member  212 . The shroud is made of a generally pliable material to prevent damage to tissue of the patient prior to use of the apparatus  10 . 
         [0034]    In operation, the second embodiment of apparatus  10  of  FIGS. 2-5  is inserted within a patient&#39;s heart and the lead  100  is received within the groove  220  at the distal end  216  of the outer tubular member  212 . When receiving the lead  100  within the groove  220 , the inner shaft  222  and blade  230  are in a home position such that the blade  230  is generally offset from the groove  220 . A positioning mechanism (not shown) may be included to bias the inner shaft  222  and blade  230  to the home position within the outer tubular member  212 . When positioned to receive the lead  100  the pliable shroud is urged away from the distal end  216  to expose the groove  220  and blade  230 . When the distal end  216  of the outer tubular member  212  is positioned as close as possible to the embedded electrode of the lead, the handle  228  of the inner shaft  222  is rotated and the blade  230  contacts the lead. Further rotation of the inner shaft  222  and the blade  230  cuts the lead  100 . The apparatus  10  is then removed from the patient. 
         [0035]    Now referring to  FIGS. 6-7 , a third embodiment of the apparatus  10  of the present invention is illustrated. The apparatus  10  includes a tubular member  312  having a proximal end  314  and a distal end  316 . The tubular member  312  is generally flexible and preferably made from a plastic or elastomeric material. 
         [0036]    A housing  318  is generally disposed at the distal end  316  of the tubular member  312 . The housing  318  includes an opening  320  for receiving the endocardial lead  100 . Preferably, the housing  318  is made of stainless steel and is joined to the distal end  316  of the tubular member  312  by use of an adhesive. However, any technique for joining the housing  318  and the distal end  316  of the tubular member  312  is contemplated by the present invention. 
         [0037]    Disposed within the housing  318  are a blade  322  and a plunger  324 . The blade  322  is received within the plunger  324 , preferably by press-fitting the blade  322  within the plunger  324 . The blade  322  is made of carbide and moveable between an extended position and a retracted position. When in the extended position, the blade  322  is received within the opening  320  of the housing  318  to cut the lead  100  received therein. 
         [0038]    The tubular member  312  includes a handle  326 . The handle  326  is joined to the proximal end  314  of the tubular member  312  by adhesive and the like. Alternately, the handle  326  is press fit within the proximal end  314  of the tubular member  312 . The handle  326  is utilized to actuate the blade  322  between the extended and retracted positions. 
         [0039]    Further, the apparatus  10  of the third embodiment includes an adjustment mechanism generally referred to at  328 . The adjustment mechanism  328  moves the blade  322  between the extended and retracted positions. Specifically, the adjustment mechanism  328  may comprise a screw  330 . A first end  332  of the screw  330  is received at a proximal end  334  of the plunger  324 . A second end  336  of the screw  330  extends through a retainer  338 . The retainer  338  is generally disposed at a proximal end  340  of the housing  318 . 
         [0040]    The adjustment mechanism  328  further includes a universal joint  342  and drive wire  344 . The universal joint  342  is disposed at the second end  336  of the screw  330 . The universal joint  342  is also attached to the drive wire  344 . The drive wire  344  extends through the tubular member  312  and attaches to the handle  326 . Further, the handle  326  includes a knob  346 . The knob  346  rotates to adjust the blade  322  between the extended and retracted positions. 
         [0041]    In operation, the apparatus  10  of the third embodiment of the present invention of  FIGS. 6-7  is inserted within a patient&#39;s heart and receives the lead  100  within the opening  320  of the housing  318 . The adjustment mechanism  328  is actuated by rotating the knob  346 . Rotational motion from the knob  346  is transferred through the drive wire  344  and universal joint  342  to rotate the screw  330 . Rotation of the screw  330  advances the screw through the retainer  338  to move the plunger  324  and blade  322  from the retracted position to the extended position. Accordingly, the blade  322  is received in the opening  320  of the housing  318  and contacts the endocardial lead  100 . The lead  100  is then cut by further extension of the blade  322  and the apparatus  10  is removed from within the patient. 
         [0042]    Referring to  FIG. 8 , the fourth embodiment of the apparatus  10  of the present invention is illustrated. The apparatus  10  includes a tubular member  412  having a proximal end  414  and a distal end  416 . The distal end  416  is generally u-shaped to define a first cutting surface  418 . At the proximal end  414  of the tubular member  412  is a handle  420 . The tubular member  412  may be generally flexible to move within the patient. 
         [0043]    Disposed within the tubular member  412  is a tension member  422 . The tension member  422  includes a proximal end  424  and a distal end  426 . The proximal end  424  of the tension member  422  is fixed to a lever  428 . The distal end  426  of the tension member  422  is fixed to a blade  430 . The blade  430  is pivotally connected to the distal end  416  of the tubular member  412  and actuation of the lever  428  about the handle  420  pivots the blade  430  to capture the lead  100  between the blade and the first cutting surface  418 . 
         [0044]    Further, blade  430  has a generally s-shaped configuration and defines a first end  432 , a second end  434  and a connecting leg  436  extending therebetween. The first end  432  includes an inner surface that defines a second cutting surface  438 . The second end  434  is fixed to the proximal end  424  of the tension member  422 . The connecting leg  436  of the blade  430  is pivotally connected to the distal end  416  of the tubular member  412 . As illustrated the blade  430  is connected to the distal end  416  of the tubular member  412  generally at the midpoint of the connecting leg  436 . However, alternative fastening positions or techniques are easily contemplated by one skilled in the art. 
         [0045]    In operation, the apparatus  10  of the fourth embodiment is placed within a patient and the lead  100  is received within the u-shaped distal end  416  of the tubular member  412  such that the first cutting surface  418  contacts the lead  100 . The lever  428  is actuated about the handle  420  to draw the tension member  422  away from the distal end  416  and pivot the blade  430  thereabout. When the blade  430  is pivoted, the second cutting surface  438  of the first end  432  also contacts the lead  100  to capture the lead  100  therebetween. Further actuation of the lever  428  and the cutting surfaces  418 ,  438  cut through the endocardial lead  100 . 
         [0046]    Referring to a fifth embodiment of  FIG. 9 , the apparatus  10  includes a tubular member  512  having a proximal end  514  and a distal end  516 . The distal end  516  is generally c-shaped to define a first cutting surface  518 . At the proximal end  514  of the tubular member  512  is a handle  520 . The tubular member  512  may be generally flexible to move within the patient. 
         [0047]    Disposed within the tubular member  512  is a tension member  522 . The tension member  522  includes a proximal end  524  and a distal end  526 . The proximal end  524  of the tension member  522  is fixed to a lever  528 . The distal end  526  of the tension member  522  is fixed to a blade  530 . The blade  530  is received within the tubular member  512  and disposed at the distal end  516 . Actuation of the lever  528  about the handle  520  linearly moves the blade  530  to capture the lead  100  between the blade  530  and the first cutting surface  518 . The blade  530  defines a second cutting surface  532  and capturing the lead  100  between the blade  530  and the first cutting surface  518  cuts the lead  100 . 
         [0048]    In operation, the apparatus  10  of the fifth embodiment is placed within a patient and the lead  100  is received within the c-shaped distal end  516  of the tubular member  512  such that the first cutting surface  518  contacts the lead  100 . The lever  528  is actuated about the handle  520  to draw the tension member  522  away from the distal end  516  and move the blade  530  linearly. When the blade  530  is moved, the second cutting surface  532  of the blade  530  also contacts the lead  100  to capture the lead  100  between the blade  530  and the first cutting surface  518 . Further actuation of the lever  528  and the cutting surfaces  518 ,  532  cut through the endocardial lead  100 . 
         [0049]    Now referring to  FIGS. 10-11 , the sixth embodiment of apparatus  10  of the present invention is illustrated. The apparatus  10  includes a tubular member  612  having a proximal end  614  and a distal end  616 . The distal end  616  includes a housing  618  while the proximal end  614  includes an adjustment mechanism  620 . The tubular member  612  may be generally flexible to move within the patient and optionally include reinforcements such as a braid or compressed coil to strengthen the tubular member  612  and resist compression during operation. 
         [0050]    Disposed within the tubular member  612  is a tension member  622 . The tension member  622  includes a proximal end  624  and a distal end  626 . The proximal end  624  of the tension member  622  is fixed to the adjustment mechanism  620  while the distal end  626  is connected to two blades  628 . The adjustment mechanism  620  moves the tension member  622  and the blades  628  between an extended position and a retracted position. 
         [0051]    The adjustment mechanism  620  includes a handle  630  for actuating the tension member  622  and blades  628  between the extended and retracted positions. Pivotally connected to the handle  630  is a lever  632  with a biasing mechanism  634 , such as a spring and the like, disposed therebetween. The biasing mechanism  634  urges the lever  632  about the handle  630  and hence, the tension member  622  and blades  628  to one of either the extended or retracted positions. Optionally, the adjustment mechanism  620  may also include a knob  636  for actuating the tension member  622  and blades  628  to a position opposite of the bias of the handle  630  and lever  632  configuration. Further, various alternatives for actuating the tension member  622  and blades  628  between positions are contemplated by the present invention, especially techniques previously described in the present application. 
         [0052]    Referring to  FIGS. 11A-11C , the blades  628  of the present embodiment are pivotally connected and may generally be described as have a scissor cutting action. The blades  628  are made of a generally hardened material such as hardened steel, carbide and the like. The blades  628  are general arcuate to define an inner cutting surface  638 . Each blade  628  includes a first end  640  and a second end  642 . The first ends  640  of the blades  628  are generally rounded or blunt-tipped to minimize damage to surrounding tissue when within a patient. The second ends  642  of the blades  628  are connected to the distal end  626  of the tension member  622 . 
         [0053]    The blades  628  are received within the housing  618  disposed at the distal end  616  of the tubular member  612 . The housing  618  is preferably made from plastic and includes tapered sides  644 . The tapered sides  644  urge the blades  628  to pivot about each other when moved from the extended position to the retracted position within the housing  618 . 
         [0054]    Optionally, the apparatus  10  of the sixth embodiment may also include a capture mechanism (not shown). The capture mechanism is disposed within the tubular member  612 . The capture mechanism is preferably a wire, more preferably a deflectable guide or snare wire, made of a flexible or bendable material and having a biased arcuate distal end (also not shown). The capture mechanism is moveable between an extended position and a retracted position similar to the tension member  622  and the blades  628 . When extended, the biased arcuate distal end wraps around the endocardial lead  100 , by way of example only, by snaring the lead, to draw the lead  100  close to the distal end  616  and housing  618  of the tubular member  612 . When retracted, the biased arcuate distal end is generally longitudinal and received within the housing  618  and tubular member  612 . 
         [0055]    In operation, the apparatus  10  of the sixth embodiment is placed within a patient. The capture mechanism is extended and the biased arcuate distal end wraps about the endocardial lead  100 . The capture mechanism is retracted to draw the lead  100  close to the distal end  616  and housing  618  of the tubular member  612 . The tension member  622  and blades  628  are extended as shown in  FIG. 11A . The adjustment mechanism  620  is actuated and the tension member  622  and blades  628  are moved to the retracted position. As seen in  FIG. 11B , the blades  628  pivot about each other at the second end  642  to capture the lead  100  between the inner cutting surfaces  638  of the blades  628 . Further actuation and retraction of the tension member  622  and blades  628  cuts through the lead  100  as shown in  FIG. 11C . The apparatus  10  is then removed from within the patient. 
         [0056]    While the present invention has been particularly shown and described with reference to the foregoing preferred and alternative embodiments, it should be understood by those skilled in the art that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention without departing from the spirit and scope of the invention as defined in the following claims. It is intended that the following claims define the scope of the invention and that the apparatus within the scope of these claims and their equivalents be covered thereby. This description of the invention should be understood to include all novel and non-obvious combinations of elements described herein, and claims may be present in this or a later application to any novel and non-obvious combination of these elements. The foregoing embodiments are illustrative, and no single feature or element is essential to all possible combination that may be claimed in this or a later application. Where the claims recite “a” or “a first” element of the equivalent thereof, such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements.