Patent Publication Number: US-2020297471-A1

Title: Self-expandable surgical implant for correcton of congenital diaphragmatic hernia

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority to U.S. Provisional Patent Application Ser. No. 62/820,395, filed Mar. 19, 2019, and U.S. Provisional Patent Application Ser. No. 62/821,504, filed Mar. 21, 2019, the disclosures of which are expressly incorporated herein by reference. 
    
    
     BACKGROUND AND SUMMARY OF THE DISCLOSURE 
     The present invention relates generally to surgical implants for repairing tissue openings and, more particularly, to such surgical implants for the thoracoscopic correction of congenital diaphragmatic hernias (CDH). Thorascopic repair typically involves primary or patch closure of the defect. Such surgical implants and associated methods are of particular interest to pediatric surgeons. Conventional approaches can present recurrences and technical difficulties due to the suture tension on large defects. The use of patches requires demanding thoracoscopic skills, and therefore primary closure with tight sutures is often pursued, which increases the risk of recurrence. 
     Embryologically, the diaphragm is formed between the eighth and tenth week of gestation, which results in the separation of the abdominal cavity and the thoracic compartment. For a congenital diaphragmatic hernia (CDH) to occur, there must be a disorder in the embryonic development of this muscle and tendon, the location and size being variable. As a consequence of this fusion defect, part of the abdominal content passes into the thorax. 
     Congenital diaphragmatic hernia (CDH) is a defect that occurs in 1 in 3,000 live births, of which approximately 60% occur in isolation without other congenital anomalies. As is known, congenital diaphragmatic hernias (CDH) are of two main types: Bochdalek hernias and Morgagni hernias. The most frequent diaphragmatic hernia is the Bochdalek hernia (95% of cases). A Bochdalek hernia is a congenital abnormality in which an opening exists in the infant&#39;s diaphragm, allowing normally intra-abdominal organs (particularly the stomach and intestines) to protrude into the thoracic compartment. It consists of a posterolateral defect, more frequent on the left side. Morgagni hernia, ventral and parasternal defect, is more prevalent on the right side. A hiatal hernia occurs when the gastroesophageal junction travels to the chest through the esophageal hiatus, being more frequent in adults. 
     The size of the diaphragmatic defect is variable and decisive in prognosis and mortality, since it clearly correlates with the degree of severity of pulmonary hypoplasia.  FIG. 1  shows the location of different diaphragmatic hernias, including Bochdalek hernia  2 , Morgagni hernia  4 , and hiatal hernia  6 .  FIG. 2  illustrates different size Bochdalek hernias, such as small defects type A, intermediate type B, large type C, and at the end of the spectrum, the complete agenesis of the hemidiaphragm in type D. Illustratively, the size of the defect in Bochdalek hernias include type A of less than 3 cm, type B and C of intermediate size, and up to type D with agenesis of the diaphragmatic leaf 
     The present disclosure relates to a system and associated methods for thoracoscopic surgery in newborns including a novel surgical implant or patch that facilitates the suturing process thereby minimizing the risk of injury of the underlying viscera. The illustrative surgical implant has characteristics of self-expandability and a traction central suture to stabilize the implant when it is located in the abdominal side of the patient. The surgical implant illustratively includes a folding pocket receiving an elastic ring that facilitates suturing a mesh to the diaphragmatic muscle when covering the abdominal viscera. 
     According to an illustrative embodiment of the present disclosure, surgical implant for repairing a tissue opening includes a body having a proximal member, a distal member coupled to the proximal member, and a peripheral pocket. The peripheral pocket is defined by a reentrant outer edge of the distal member extending around an outer edge of the proximal member. A resilient ring is received within the peripheral pocket and is configured to apply tension to the body. 
     According to a further illustrative embodiment of the present disclosure, a method of forming a surgical implant includes the steps of providing a thoracic member having a proximal surface and a distal surface, providing an abdominal member having a proximal surface and a distal surface, and positioning the distal surface of the thoracic member adjacent to the proximal surface of the abdominal member. The method further includes the steps of folding an outer rim of one of the abdominal member and the thoracic member over an outer edge of the other of the thoracic member and the abdominal member to define a reentrant lip, and securing the thoracic member to the abdominal member by the reentrant lip. The method further includes the steps of defining a peripheral pocket with the reentrant lip, and inserting a support ring within the peripheral pocket. 
     According to another illustrative embodiment of the present disclosure, a method of attaching a surgical implant to a diaphragmatic hernia includes the steps of providing a surgical implant including a body having a proximal member, a distal member coupled to the proximal member, a peripheral pocket defined by a reentrant outer rim of the distal member extending around an outer edge of the proximal member, and a support ring received within the peripheral pocket and configured to apply tension to the body, and folding the surgical implant. The method further includes the steps of passing the folded surgical implant from a thoracic compartment, through a diaphragmatic rim, and into the abdominal cavity, and expanding the support ring to apply tension to the body of the surgical implant. The method further includes the steps of pulling a central suture coupled to the body to stabilize the surgical implant against the diaphragmatic rim, and suturing the body of the surgical implant to the diaphragmatic rim. 
     Additional features and advantages of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrative embodiment exemplifying the best mode of carrying out the invention as presently perceived. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The detailed description of the drawings particularly refers to the accompanying figures in which: 
         FIG. 1  is a cross-sectional view of different illustrative diaphragmatic hernias; 
         FIG. 2  is a cross-sectional view of different illustrative Bochdalek type congenital diaphragmatic hernias (CDH); 
         FIG. 3  is a cross-sectional view of a surgical implant according to an illustrative embodiment of the present disclosure placed in a diaphragmatic opening; 
         FIG. 4  is an exploded perspective view of a thoracic member of the illustrative surgical implant of  FIG. 3 ; 
         FIG. 5  is a perspective view of the thoracic member of  FIG. 4 ; 
         FIG. 6  is an exploded perspective view of an abdominal member of the illustrative surgical implant of  FIG. 3 ; 
         FIG. 7  is a perspective view of the abdominal member of  FIG. 6 ; 
         FIG. 8  is an exploded perspective view of the thoracic member and the abdominal member of the illustrative surgical implant of  FIG. 3 ; 
         FIGS. 9A-9C  are cross-sectional views, in partial schematic, showing assembly steps of the illustrative surgical implant of  FIG. 3 ; 
         FIGS. 10A and 10B  are perspective views showing the support ring inserted within the peripheral pocket of the illustrative surgical implant of  FIG. 3 ; 
         FIG. 11  is a perspective view of the illustrative surgical implant of  FIG. 3 , including a central placement suture; 
         FIG. 12  is a perspective view showing the central suture providing traction for stability against a diaphragmatic rim; 
         FIG. 13  is a perspective view of the thoracic side of the illustrative surgical implant of  FIG. 3  in situ; 
         FIG. 14  is a perspective view of the abdominal side of the illustrative surgical implant of  FIG. 3  in situ; 
         FIG. 15A  is a graph showing surgical time for representative surgical implant placements; 
         FIG. 15B  is a heat map showing surgical time for representative surgical implant placements; 
         FIG. 16  is a graph showing mean of good quality stitches per representative surgical implant, with wiskers illustrating standard deviation; 
         FIG. 17A  is a graph showing the level of difficulty for representative surgical implant placements; and 
         FIG. 17B  is a graph of the Likert scale for representative surgical implant placements. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to the embodiments illustrated in the drawings, which are described herein. The embodiments disclosed herein are not intended to be exhaustive or to limit the invention to the precise form disclosed. Rather, the embodiments are chosen and described so that others skilled in the art may utilize their teachings. Therefore, no limitation of the scope of the claimed invention is thereby intended. The present invention includes any alterations and further modifications of the illustrated devices and described methods and further applications of principles in the invention which would normally occur to one skilled in the art to which the invention relates. 
     With reference to  FIG. 3 , an illustrative surgical implant  10  is configured to be supported by a diaphragm  12  intermediate a thoracic compartment  14  and an abdominal cavity  16 . More particularly, the implant  10  is supported within a defect, illustratively a diaphragmatic opening  18  defined by a diaphragmatic rim  20 . In the following detailed description, the surgical implant  10  may also be referred to as a patch or self-expandable mesh (SeM). 
     With reference to  FIGS. 3-10B , the surgical implant  10  illustratively includes a body  22  including a proximal member  24  coupled to a distal member  26 . A reentrant outer lip  28  of the distal member  26  defines a peripheral pocket  30  receiving a support ring  32  thereby expanding the surgical implant  10 . 
     With reference to  FIGS. 4 and 5 , the proximal member  24  is illustratively a circular thoracic member  34  including a first or proximal mesh layer  36  coupled to a second or distal mesh layer  38 . An adhesive layer  40  illustratively couples the first mesh layer  36  to the second mesh layer  38 . The first mesh layer  36  and the second mesh layer  38  are illustratively circular disks having a proximal outer diameter (PD 1 ). In an illustrative embodiment, the proximal outer diameter (PD 1 ) is approximately 6 cm. 
     The proximal member  24  is illustratively formed of a mesh material such as a synthetic biocompatible material. More particularly, each mesh layer  36  and  38  of the proximal member  24  are illustratively formed of a stretchable nonwoven polyester with a hypoallergenic polyacrylate adhesive surface  42  and  44 , respectively. Releasable liners  43  and  45  may cover the adhesive surfaces  42  and  44 , respectively, until assembled into the proximal member  24 . In one illustrative embodiment, the mesh layers  36  and  38  may be formed from Fixomul R  Stretch dressing material (Ref 70022-00 available from BSN Medical GmbH of Hamburg, Germany). The proximal member  24  may be adapted to any suitable material, synthetic or biocompatible. For example, a polytetrafluoroethylene (ePTFE) material may be used for the proximal member  24  (such as Dualmesh® Biomaterial, available from W. L. Gore &amp; Associates of Flagstaff, Ariz.). 
     During assembly of the thoracic member  34 , two circular mesh layers  36  and  38  of substantially equal outer diameters (PD 1 ) (illustratively, 6 cm each) are positioned with their adhesive surfaces  42  and  44  facing one another following removal of the liners  43  and  45 . The adhesive surfaces  42  and  44  are then brought into contact with each other such that the surfaces  42  and  44  together define the adhesive layer  40  ( FIG. 4 ) for securing the first mesh layer  36  with the second mesh layer  38 . 
     With reference to  FIGS. 6 and 7 , the distal member  26  is illustratively a circular abdominal member  47  including a first or proximal mesh layer  46  coupled to a second or distal mesh layer  48 . An adhesive layer  50  illustratively couples the first mesh layer  46  and the second mesh layer  48 . The first mesh layer  46  illustratively has a first distal outer diameter (DD 1 ), and the second mesh layer  48  illustratively has a second distal outer diameter (DD 2 ). Illustratively, the second distal outer diameter (DD 2 ) is greater than the first distal outer diameter (DD 1 ), thereby defining an outer rim  60 . In an illustrative embodiment, the first distal outer diameter (DD 1 ) is approximately 6 cm, while the second distal outer diameter (DD 2 ) is approximately 8 cm. As such, the outer rim  60  has a width (W) of approximately 1 cm. 
     The distal member  26  is illustratively formed of a mesh material such as a synthetic biocompatible material. More particularly, each mesh layer  46  and  48  of the distal member  26  are illustratively formed of a stretchable nonwoven polyester with a hypoallergenic polyacrylate adhesive surface  52  and  54 , respectively. Releasable liners  56  and  58  may cover the adhesive surfaces  52  and  54 , respectively, until assembled into the distal member  26 . In one illustrative embodiment, the mesh layers  46  and  48  may be formed from Fixomul R  Stretch dressing material (Ref 70022-00 available from BSN Medical GmbH of Hamburg, Germany). 
     The distal member  26  may be formed of any kind of synthetic or biocompatible material, if it complies with the functional features including sufficient resiliency to be compressed and subsequently expanded by the support ring  32  received within the pocket  30 . For example, a polytetrafluoroethylene (ePTFE) material may be used for the distal member  26  (such as Dualmesh® Biomaterial, available from W. L. Gore &amp; Associates of Flagstaff, Ariz.). 
     During assembly of the distal member  26  as shown in  FIGS. 8-10B , two circular mesh layers  46  and  48  of different outer diameters (DD 1 ) and (DD 2 ) (illustratively, 6 cm and 8 cm, respectively) are positioned with their adhesive surfaces  52  and  54  facing one another following removal of the liners  56  and  58 . The adhesive surfaces  52  and  54  are then brought into contact with each other such that the surfaces  52  and  54  together define the adhesive layer  50  ( FIGS. 6 and 7 ) for securing the first mesh layer  46  with the second mesh layer  48 . 
     As noted above, the surgical implant  10  can be formed of a wide variety of synthetic biocompatible materials, if it complies with the required functional features. For the creation of the proximal member  24 , two circular mesh layers  36  and  38  of 6 cm outer diameter are pasted on top of each other, with their adhesive surfaces  42  and  44  facing one another ( FIGS. 4 and 5 ). For the distal member  26 , two circular mesh layers  46  and  48  of 6 and 8 cm outer diameters are pasted on top of each other as described for the proximal member  24  ( FIGS. 6 and 7 ). 
     Next, the proximal member  24  and the distal member  26  are approached to each other ( FIG. 8 ). The 2 cm difference between the between the two members  24  and  26  define the outer rim  60  having a width (W) of 1 cm. The outer rim  60  is folded over an outer edge  62  of the proximal member  24  to define the reentrant outer lip  28 . The adhesive surface  52  on the mesh layer  48  of the distal member  26  secures the reentrant outer lip  28  to the mesh layer  36  of the proximal member  24  to create the pocket  30  ( FIGS. 9A-9C ). Afterwards, a center  66  of the proximal member  24  is cut away to open access to the pocket  30  ( FIG. 9B ) where the support ring  32  is received ( FIGS. 9C-10B ). 
     The support ring  32  is illustratively a semi-rigid annular member having a shape memory, so the surgical implant  10  will remain expanded ( FIG. 9C ), illustratively to an outer diameter equal to DD 1  (e.g., approximately 6 cm). Illustratively, the support ring  32  may be formed of a resilient polymer, such as an elastomer and/or silicone. In one illustrative embodiment, the support ring  32  is formed from the stent positioner of a pigtail ureteral stent (Ref. 036308 available from Cook Medical of Bloomington, Ind.), by joining the opposing ends with n-butyl-2-cyanoacrylate adhesive (Ref. 1050052 available from B Braun Histoacryl® of Bethlehem, Pa.). 
     A central placement suture  70  is illustratively secured in the center of the distal member  26  of the surgical implant  10  that allows traction from the thoracic compartment  14  against the diaphragmatic rim  20 , providing in situ stability for the suturing process ( FIGS. 11-14 ). Illustratively, the central placement suture  70  is a 20 cm 2/0 silk suture. 
     An illustrative method of attaching the surgical implant  10  to a diaphragmatic hernia  18  may utilize known minimally invasive surgical procedures, such as videotorascopic techniques. Illustratively, the method includes an initial step of compressing, illustratively folding, the surgical implant  10 . More particularly, the surgical implant  10  is collapsed or rolled for passing from the thoracic compartment  14 , through the opening  18  defined by the diaphragmatic rim  20 , and into the abdominal cavity  16 . A conventional surgical instrument, such as a trocar, may be used to position the surgical implant  10 . More particularly, after having reduced the herniated intestine, the surgical implant  10  is moved to the abdominal cavity  16  through the defect  18  with the support ring  32  providing for expansion of the body  22 . 
     The surgical implant  10  is configured to self-expand as a result of the support ring  32  received within the pocket  30 . Once the support ring  32  is expanded in the abdominal side of the defect  18 , the body  22  remains deployed in close contact with the diaphragmatic rim  20  by positive pressure of the abdominal cavity  16  and the negative pressure of the thoracic compartment  14  (the pressure differential being represented by arrows  72  in  FIG. 3 ). 
     Once the surgical implant  10  is adequately positioned within the abdominal cavity  16 , the central placement suture  70  is illustratively pulled axially toward the thoracic compartment  14  through a surgical instrument (e.g., a trocar) to assist in keeping the surgical implant  10  in place during the suturing process. The surgical implant  10  is illustrated as being positioned below the diaphragmatic rim  20  supported on the edges of the defect  18  and enhanced by external traction of the central placement suture  70 . 
     Conventional sutures or stitches  74  are illustratively used to secure the body  22  of the surgical implant  10  to the diaphragm  12 . More particularly, stitches  74  may secure the pocket  30  and/or support ring  32  to the diaphragmatic rim  20 . The suturing can be performed using intracorporeal or extracorporeal knot-tying technique. Illustratively, at least 8 equidistant interrupted stitches  74  with at least 3 throws per knot are provided to secure the surgical implant  10 . It should be appreciated that the number of stitches  74  can vary with the size of the surgical implant  10  and/or the defect  18 . After the suturing process is complete, the central placement suture  70  can be cut away. It should be appreciated that the support ring  32  may remain within the pocket  30  following the suturing step, or be removed from the pocket  30  depending upon the type and placement of the stitches  74  relative to the surgical implant  10 . 
     The surgical implant  10  isolates and protects all the abdominal viscera. The proximity of the free edge of the pocket  30  in the thoracic side to the diaphragmatic margins allows an easy and precise suture with continuous or interrupted stitches  74 . The distal mesh  26  forges a pocket  30  around the ring  32 , embracing it. The margins of that pocket  30  in his thoracic side will be facing the diaphragmatic rim  20  to allow an easy and precise suture. Eventually, the support ring  32  will give a safe surface below every stitch to avoid inadvertent injuries of the underlying viscera. Finally, the surgical implant  10  is essentially stable due to a traction central placement suture  70  that keeps the implant  10  in close contact with the diaphragmatic rim  20  ( FIG. 3 ). 
     An inanimate model for the thoracoscopic repair of congenital diaphragmatic hernia (CDH) was used to recreate the surgical technique. In the following description, different variables are compared for both the surgical implant  10  of the present disclosure (identified as self-expanding mesh (SeM)) and known patches (identified as conventional mesh (CM)). Illustratively, nine CDH cases were repaired with each type of mesh (n=18 CDH cases) in an inanimate model of the disease by experiences pediatric surgeons. 
     Quantitative and qualitative data results are expressed as mean +/−standard deviation (SD). For the comparison of not normal distributed groups, differences between means were compared using Mann-Whitney test. Statistical analysis and figures were made using the Prism 8 package (available from Graphpad Software Inc. of La Jolla, Calif.), and p value&lt;0.05 was considered statistically significant. 
     With reference to  FIGS. 15A and 15B , the variable of surgical time for placement of surgical implant is assessed in minutes from its introduction through the port of the surgical instrument until its complete suture.  FIG. 15A  shows the average surgical time taken for each mesh with distribution and standard deviation for nine placements. The surgical time taken for SeM placement was significantly lower (29.3±5.6 minutes) compared to 33.2±5.9 minutes for the CM (*p&lt;0.05, Mann-Whitney). The differences in time used to place and suture the different implants can be observed in the heatmap of  FIG. 15B . 
     With reference to  FIG. 16 , the variable of quality of the suturing process is assessed by quantifying the number of good quality knots (with at least three throws per knot, tight enough to the implant and the diaphragmatic rim), and the occurrence of an adverse event during the suturing such as bowel injury, diaphragmatic rips or large gaps between knots.  FIG. 16  shows the mean of good quality stitches/knots per surgical implant with wiskers showing standard deviation. The number of good quality stitches/knots per mesh was in average 7.9±0.3 for SeM and 7.3±1 for CM, considering that the number of stitches placed per mesh was 8. The percentage of surgeries in which all the knots were good quality (scoring 8 out of 8) were 55.6% for CM and 88.8% for SeM. 
     The adverse events occurring during the suturing process were 1 for the SeM (diaphragmatic rip n=1) and 7 for the CM (bowel injury n=2, diaphragmatic rip n=2, and large gaps between knots n=3). 
       FIGS. 17A and 17B  show the assessment of the level of difficulty of the surgical procedure using a five-point Likert scale (Very Easy, Easy, Intermediate, Difficult and Very Difficult).  FIG. 17A  is a Violin plot for each surgical implant&#39;s Likert scale and data distribution. The level of difficulty reported for each procedure using the five-points Likert scale were 4.8±0.3 and 4.0±0.5 for the SeM and CM respectively (**p≤0.001, Mann-Whitney) ( FIG. 17A ).  FIG. 17B  shows the Likert scale for each surgical implant. SeM placement was reported to be Very easy (n=8) and Easy (n=1), and for the CM was Very easy (n=1), Easy (n=7) and Intermediate (n=1) ( FIG. 17B ). 
     In summary, nine cases of CDH were repaired with each type of implant (SeM and CM). The total duration of the procedure was shorter when using the self-expandable mesh (SeM) 10 when compared to the conventional mesh (CM) (p&lt;0.05). The level of difficulty was reported to be lower for the self-expandable mesh (SeM) 10 (p&lt;0.001). The number of good quality knots was higher and adverse events were less common for the self-expandable mesh (SeM) 10, with no visceral injury observed. 
     The surgical implant of the present disclosure in the form of a stabilizing self-expanding mesh (SeM) offers a safe and ergonomic performance for the thoracoscopic repair of congenital diaphragmatic hernia (CDH) facilitating the surgical technique, especially for large defects where the primary closure can lead to recurrences. The main advantages of this surgical implant are that it keeps the viscera isolated into the abdomen while offering a flap on the thoracic side for suturing in a comfortable and practical fashion, minimizing the risk of visceral injury and saving surgical time that is especially precious in patients with pulmonary hypertension. The quality of the suturing process is superior with this novel surgical implant system and although in this surgical model is not possible to follow-up for the analysis of long term results, it would be interesting to study in animal models if these immediate benefits observed in the surgery, have some impact in the recurrence of the disease. The surgical implant of the present disclosure is synthetic but is customizable and could be made with biological materials as well. 
     This novel mesh has been created to facilitates the thoracoscopic repair of the neonatal CDH. It has characteristics of self-expandability due to the presence of a semi-rigid ring. Once the ring is expanded in the abdominal side of the defect, it remains deployed in close contact with the diaphragmatic rim facilitated by the positive pressure of the abdominal cavity and the negative pressure of the thoracic compartment. The mesh itself will isolate and protect the viscera in the abdominal compartment, minimizing the risk of injury. 
     While the present invention has been illustrated by the description of embodiments thereof, and while the embodiments have been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will be readily apparent to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative system and method, and illustrated examples shown and described. Accordingly, departures may be made from such details without departing from the scope or spirit of the invention.