Abstract:
A lung volume reduction system includes a percutaneously, laparoscopically or thorocospically insertable delivery element comprising a control end which remains outside the body and an insertion end which, when in an operative position, is adjacent to an external surface of a target portion of a lung and a constriction element deployable from the distal end of the delivery element to apply compressive force to an external surface of the target portion of the lung to constrict at least one airway therein and collapse the target portion of the lung.

Description:
PRIORITY CLAIM 
     This application claims the priority to the U.S. Provisional Application Ser. No. 60/973,269, entitled “Compression, Banding and Percutaneous Airway Ligation of Emphysematous Lung Tissue,” filed Sep. 18, 2007. The specification of the above-identified application is incorporated herewith by reference. 
    
    
     BACKGROUND 
     Emphysema, a progressive, often incurable disease of the lungs often results from chronic infection or irritation of the bronchial tubes. As the bronchial tubes become irritated, some of the airways may be obstructed, trapping air in the alveoli. As this process continues, the alveoli become enlarged and exchange oxygen for carbon dioxide less efficiently. Furthermore, these expanded portions of the lungs may compress adjacent healthy portions of the lungs interfering with their functioning. 
     Lung volume reduction surgery (LVRS) is one treatment used to relieve the symptoms of emphysema by removing diseased portions of the lungs to create more room for the remaining healthy portions. Although LVRS has been shown to improve pulmonary function and the survival rate in selected patients the complications associated with such major, open surgical procedures make LVRS unsuitable for certain patients. 
     Minimally invasive procedures have also been employed to achieve results similar to those of LVRS while minimizing the associated complications. These less invasive procedures generally involve depositing in the lungs devices that restrict the flow of air to the diseased portions of the lungs. Often, a bronchoscope or laparoscope is used to deliver the devices obviating the need for surgical openings into the chest cavity. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a lung volume reduction system comprising a percutaneously insertable delivery element comprising a control end which remains outside the body and an insertion end which, when in an operative position, is adjacent to an external surface of a target portion of a lung and a constriction element deployable from the distal end of the delivery element to apply compressive force to an external surface of the target portion of the lung to constrict at least one airway therein and collapse the target portion of the lung. As would be understood by those skilled in the art, this collapsed condition may, if desired, be continued for a period of time sufficient to necrose the collapsed portion of tissue permanently eliminating the inefficiencies of this diseased portion of tissue from the lung. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing an embodiment of a device used to collapse a lung according to the present invention; 
         FIG. 2  is a diagram showing another embodiment of a device used to collapse a lung using a mechanical tie according to the present invention; 
         FIG. 3  is a diagram showing an embodiment of a percutaneous airway lung ligation band according to the present invention, during deployment; and 
         FIG. 4  is a diagram showing the lung ligation band of  FIG. 3  after deployment; and 
         FIG. 5  is a diagram showing a further embodiment of a device used to collapse a desired portion of lung using an elastic bag, according to the present invention; 
         FIG. 6  is a diagram showing a further embodiment of a device used to collapse a desired portion of lung according to the present invention; and 
         FIG. 7  shows an apparatus according to a further embodiment of the invention for collapsing a desired portion of lung. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention may be further understood with reference to the following description and the appended drawings, wherein like elements are referred to with the same reference numerals. The present invention relates to devices for treatment of emphysema and more specifically relates to devices for reducing the size of diseased lung tissue to improve the functioning of remaining healthy tissue. 
     According to embodiments of the present invention, a percutaneous procedure is employed to access diseased regions of the lungs and to deploy thereto devices to reduce the volume of the diseased tissue increasing the efficiency of the healthy tissue. 
     The exemplary embodiments of the present invention comprise procedures employing banding and/or compression devices to reduce the volume of emphysematous tissue. Depending on the details of a particular case, these devices may be deployed from outside or within the lung. The exemplary devices according to the present invention isolate targeted tissue from portions of the lungs upstream thereof to reduce the volume by preventing further influx of air. Other devices according to the invention compress the target tissue to decrease its volume. 
       FIG. 1  shows an exemplary embodiment of a system  100  for collapsing a target portion of the lung by clamping or pinching a lobe of the lung. The system  100  includes a rivet or peg  102  which is placed into the thoracic cavity and inserted through a target lobe  112  of a lung  110 . The rivet or peg  102  is preferably inserted minimally invasively through, for example, a laparoscope or thoracoscope introduced between the ribs into the thoracic cavity via a small incision with a distal end of the peg  102  being inserted through the target lobe  112  and secured in place by tightening to desired dimensions using conventional locking mechanisms or anchoring members  104 . For example, the system  100  may include a tube of substantially circular cross-section through which suction may be applied to draw a portion of lung tissue into the tube after which an elastic ligator may be pushed off the distal end of the tube so that the elastic ligator contracts to constrict the portion of the lung which has been drawn into the tube. Alternatively, as would be understood by those skilled in the art, a tie wrap may be placed around a target portion of the lung and then an end of the tie wrap may be drawn out to tighten the tie wrap around the target portion and constrict the target portion of tissue. After the distal end of the peg  102  has passed through the target lobe  112  to a desired position on a side opposite a point of insertion into the target lobe  112 , a first anchor member  104  is attached to or, alternatively, deployed from, the distal end of the peg  102  and the target lobe  112  is compressed against the first anchor member  104  to a desired degree. The distal end of the peg  102  is prevented from being pulled back into the interior of the target lobe  112  by the first anchor member  104  which engages an exterior of the target lobe  112 . Compressing the target lobe  112  against the distal end of the peg  102  reduces the volume of the target lobe  112  by creating a neck region  114  of reduced cross-sectional area. When a desired amount of compression of the target lobe  112  has been achieved, a second anchor member  104  is deployed from a proximal portion of the peg  102  to maintain the desired amount of compression of the target lobe  112 . After the second anchor member  104  has been deployed, any excess length of the peg  102  may be trimmed away and the laparoscope may be removed. Those skilled in the art will understand that the peg  102  and the anchoring members  104  are preferably adapted to engage portions of the exterior of the target lobe  112  large enough to hold the anchoring members  104  in position against forces applied thereto during respiration and as the patient moves about. 
     Constriction by the peg  102  collapses the bronchial passages in the neck region  114  preventing the passage of air to the target lobe  112  to inflate the alveoli contained therein. Thus surrounding healthy portions of the lung may inflate more freely and carry out the exchanges of gases more efficiently. Over time, the target lobe  112  will necrose because of the constriction further reducing its volume. In an alternative example, a peg  102  may be placed within a target lobe  112  and anchored across a target bronchial passage therein to prevent air flow only to that portion of the target lobe  112  served by the target bronchial passage. 
     A system  200  to reduce lung volume according to a second embodiment of the invention is shown in  FIGS. 2-4 . According to this exemplary embodiment, a mechanical element such as a tie or a clamp  202  is placed around a target portion  212  of the lung  110  to separate the target portion  212  from upstream portions of the lung  110  to collapse the target portion  212 . The tie or clamp  202  is applied around the lung  110  to compress the target portion  212  of the lung  110  downstream of an airway branch  111 . As with the peg  102  of the system  100 , the tie or clamp  202  is preferably inserted into the thoracic cavity through a minimally invasive method, such as through a laparoscopic procedure, and may be secured in place by tightening to the correct dimensions using a conventional locking mechanism  206 . Alternatively, the tie or clamp  202  may be replaced, or supplemented, by an elastic band  204  or a shape memory element which, when released around a target portion of the target lobe  212  will contract without the need for a locking mechanism to apply compression thereto. For example, the constriction element may be a loop of a shape memory material such as Nitinol formed so that, when deployed it reverts to a memorized shape with a reduced diameter. The elastic bands  204 , or other type of compression element, may also be applied through a laparoscopic procedure or other minimally invasive approach. For example, one or more elastic bands  204  may be disposed around a cylinder into which a portion of the target lobe  212  is drawn (e.g., by suction applied thereto) at which point a first one of the elastic bands  204  may be released (e.g., by drawing a trigger line attached thereto) to contract around the portion of the target lobe  212  adjacent to a distal end of the cylinder. 
     As shown in  FIGS. 3 and 4  the system  200  collapses a target portion  410  of the lung by isolating it from remaining portions of lung to cut-off the supply of air thereto. A constriction element (e.g., a tie or clamp  202  or an elastic band  204 ) is deployed from a delivery element onto the airway, so that the passage of air is blocked. For example, a tube such as an endoscope (not shown) may be inserted between the ribs into the thoracic cavity via an incision with one or more constriction elements received around a distal end of the endoscope. The distal end of the endoscope preferably includes a hollow chamber into which the target portion  410  may be drawn (e.g., under suction) so that the distal end of the endoscope and the constriction element received thereon surrounds the target portion  410 . In this position, the constriction element is moved off of the distal end of the endoscope so that it encircles a portion of the lung upstream of the target portion  410 . When the constriction element is an elastic band  204 , the band  204  tightens immediately after it passes off of the distal end of the endoscope to constrict the lung tissue therewithin, preventing the flow of air therethrough. Ties or clamps  202  deployed in this manner are then tightened around the lung tissue to prevent the flow of air to the target portion  410 . Those skilled in the art will understand that these constriction elements may be formed of bioabsorbable materials which are preferably selected to retain their form until after a time required to achieve a desired therapeutic effect has elapsed. For example, such a bioabsorbably constriction element may be selected to remain in position, as shown in  FIG. 4 , until the target portion  410  has completely collapsed and the flow passage(s) thereto are sealed. As would be understood by those skilled in the art, the system  200  may deploy the ligating bands  204  using a mechanism substantially similar to an elastic band ligating system for treating esophageal varices as described, for example, in U.S. Pat. No. RE36,629 issued to Zaslavsky, et al., Mar. 28, 2000, the entire disclosure of which is hereby incorporated by reference. 
     As shown in  FIG. 5 , a system  300  according to an additional embodiment of the lung reduction system according to the invention includes an elastic bag or sock  304  which is stretched for placement around a portion of a target lobe  312  of the lung  110 . Upon release, the bag  304  contracts to apply a compressive force to a portion of a surface of the target lobe  312  of the lung  110  larger than that affected by the clamp  202  or the ligating band  204 . That is, the open end of the bag  304  constricts air flow into the target lobe  312  of the lung  110  as in the prior embodiments while the remaining portions of the bag  304  actively compress the target lobe  312 . As would be understood by those skilled in the art, the bag  304  may be designed to apply a compressive force which is substantially equal across the surface area of the target lobe  312  with which it is in contact. Alternatively, the bag  304  may be designed to apply a force which varies over the surface area. For example, the bag  304  may be designed to apply a force which is a maximum along a line which, when the bag  304  is in a desired position on the target portion of the lobe  312 , is furthest upstream on the lobe  312  (e.g., at the open end of the bag  304 ) or to cause the collapse of portions of the target lobe  312  in a desired sequence. In the exemplary embodiment, the bag or sock  304  comprises a band  302  adapted to retain the device in place on the target portion of the lung  110 . For example, the band  302  may have an inner surface shaped to grasp the tissue of the lung and prevent it from slipping off the target lobe  312 . The band  302  may, for example, be made of an elastic material, or may be tightened mechanically as desired in a manner similar to that described above. 
     The bag or sock  304  according to the present invention is preferably made of a bioabsorbable material such as polyurethane or lycra so that it does not have to be removed after the compressed portion of the target lobe  312  has necrosed to a desired level. As with other embodiments of the present invention, the bag or sock  304  is designed to be placed using minimally invasive techniques. Specifically, the bag or sock  304  can be inserted into the body through a small incision or port on an elongated retractor device. The distal end of the retractor is generally maintained in a closed condition so that the sock  304  can be placed thereover to keep the retractor in a low profile. When the sock  304  is placed adjacent to the target lobe  312 , a handle of the retractor is activated to expand the sock  304  using, for example, three or more arms  320  for ease of placement over the target lobe  312 . The handle of the retractor may be attached, via known means, to the plurality of arms  320  so that, upon activation, the arms extend radially outward from the device. Once the sock  304  is placed in the desired location, the arms of the retractor device may be retracted in order to release the hold on the sock  304 . The arms  320  of the retractor can then be removed from the body in a closed position in order to minimize trauma to the patient. 
     As shown with respect to  FIG. 6 , the exemplary lung reduction system  400  is designed to be performed percutaneously to treat a target portion or lobe  410  of a lung  412 . Those skilled in the art will understand that the percutaneous method may be used in conjunction with an imaging modality, such as, for example fluoroscopy. Alternately, a laparoscopic procedure may be employed to facilitate visual observation during the procedure. As another possibility, the procedure may be performed thorocospically, via VATS or via the use of SPY fiber technology in one of the working channels of the scope, as those skilled in the art will understand. In this embodiment, the delivery element comprises a percutaneous axial member  404  (e.g., a flexible tube) used to deliver an elastic band  402  or other constriction element to an airway  422  such as a bronchial tube. A distal end of the axial member  404  is introduced into the body and placed adjacent to the airway  422  to be treated while a proximal end of the percutaneous axial member  404  remains outside the body for manipulation by a user for positioning of the distal end over a desired target portion of the lung  412 . 
     As would be understood by those skilled in the art, a conventional mechanism, similar to those used for band ligation of esophageal varices, may be used to deploy the elastic band  402  from the axial member  404 , so that the elastic band  402  wraps around and is anchored to a portion of the air passage  422  which had previously been drawn into the axial member  404 . For example, as described above in regard to the embodiment of  FIG. 2 , a cord extending along the length of the percutaneous rod  404  may be used to pull one elastic band  402  at a time off the axial member  404 , and release it over the air passage  422 . In another embodiment, a longitudinal member may extend along the length of the axial member  404  so that the longitudinal member may slide along the length thereof to individually release the elastic bands  402 . Alternatively, the elastic band  402  may have a length that can be varied by the user, so that it can be elongated to pass over the hyperinflated portion of the lung  410 , and then shortened to tighten around the air passage  422 . The elastic band  402 , when released over the air passage  422 , constricts to cut off air-flow to the hyperinflated target portion or lobe  410  from the rest of the lung  412  leading to necrosis of this target portion or lobe  410 . The elastic band  402  is preferably formed of biodegradable material so that it may remain in place for a substantial amount of time to prevent re-inflation of the target lobe or portion  410 ′, by blocking the air passing through the airway  422 . As would be understood by those skilled in the art, the material of the elastic band  402  is selected to remain in position for a length of time sufficient to collapse the target lobe  410 ′ to a desired level. In cases where the elastic band is not biodegradable, an additional procedure may be performed to remove the band  402  from the body after the desired level of collapse has been achieved. 
     As shown in  FIG. 7 , a system  430  similar to that described above in regard to  FIGS. 3 and 4  may be used to deploy a bag or sock similar to those described above in regard to  FIG. 5 . The system  430  includes an axial member  432  with a bag or sock member  434  with an open end  436  wrapped around the distal end of the axial member  432 . The closed end  438  of the sock member  434  extends within a lumen of the axial member  432  while an elastic member  440  extending around the open end  436  holds the sock member  434  to the distal end of the axial member  432 . After being advanced to a location adjacent a target portion  442  of lung to be treated in the same manner described above, the target portion  442  of lung is aspirated into the distal end of the axial member  432  via the application of suction or the manipulation of a grasper through the lumen of the axial member and the elastic member  440  is released from the distal end of the axial member  432  to constrict around the target portion maintaining the sock member  434  in position over the target portion  442 . 
     The present invention has been described with reference to specific exemplary embodiments. Those skilled in the art will understand that changes may be made in details, particularly in matters of shape, size, material and arrangement of parts without departing from the teaching of the invention. Accordingly, various modifications and changes may be made to the embodiments without departing from the broadest scope of the invention as set forth in the claims that follow. The specifications and drawings are, therefore, to be regarded in an illustrative rather than a restrictive sense.