1
GASTROSEAL ENDOLUMINAL CLOSURE DEVICE Making
Natural Orifice Transluminal Endoscopic Surgery
Possible Braham K. Dhillon1, Alice R. Hales1,
Laura E. Mattaliano1, John P. Sticklen1 Advised
by Mike Holzman2, M.D., M.P.H., Gus Attwell,
M.D., and Paul King1, Ph.D. Vanderbilt
University, 1Department of Biomedical
Engineering, 2Department of Surgical Science
General Surgery, 3Department of Medicine
Gastroenterology
INTRODUCTION
DESIGN PARAMETERS
FINAL DESIGN GASTROSEAL
Purpose
The GastroSeal

• Components
• Outer umbrella (a) deployed (b) packaged
• Inner umbrella (a) deployed (b) packaged
• Outer umbrella packaging sleeve
• Inner umbrella packaging sleeve
• Pushing/guiding tube

• Instrumentation Parameters
• Endoscope length 100-120 cm
• Operating port diameter
• d 2.2-4.2 mm for one port scope
• d 2.8/3.2 mm for two-port scope

• Surgical Parameters
• Stomach wall thickness 3-5 mm
• Incision length 2 cm
• Incision will seal completely in 7-14 days

The purpose of this project is to design a device
that will seal a hole in the stomach wall by
means of a typical endoscope.

• Safety Parameters
• Device must seal incision completely with no
  leakage
• Stability device must stay in place where
  implanted
• Materials must be biocompatible
• Durability device must withstand acidic
  environment

NOTES Surgery
Currently, most surgeries for disorders in the
peritoneal cavity are performed using an incision
in the abdomen. However, recently there has been
the development of a technique called natural
orifice transluminal endoscopic surgery (NOTES).
With the NOTES procedure, a flexible endoscope,
normally used for surgeries within the
gastrointestinal tract, is used to
electrosurgically make an incision in the stomach
wall to gain access to the peritoneal cavity.
The problem then is the question of how to seal
the incision once the surgery is complete.
Currently there is no reliable technique for this
task. The purpose of this project is to design a
device that will work through the operating port
of common endoscopes to stitch, clamp, staple, or
otherwise reliably seal the incision and allow it
to heal quickly.
Device Details
Part Component Material Dimensions
Outer Umbrella (1) Frame/spokes Nitinol 1.5cm center to tips
Spines Nitinol 1mm pointing inward
Center tip Nitinol 4mm in length, 1mm at widest part of tip
Covering Surgisis 7.0 cm2 surface area
Guiding wire Plastic 150cm
Inner Umbrella (2) Frame/spokes Nitinol 1.5cm center to tips
Spines Nitinol 1mm pointing outward
Center ring Nitinol 0.8mm in diameter
Covering Surgisis 7.0 cm2 surface area
Packaging Sleeves (3 and 4) NA Plastic 4 cm in length, 2.9mm OD, 2.8mm ID
Pushing/Guiding Tube (5) NA Plastic 2.6mm OD, 2.5mm ID
DESIGN PROCESS
BACKGROUND
Initial Design Ideas
Device Procedure
Schematic Theory Analysis
Nitinol Coil Wire coil would wrap around incision, similar to a notebook binding. Tip of coil would be sharp enough to pierce tissue. Idea was abandoned because the tip of the coil would be too difficult to control from outside the endoscope. Also, no way to ensure coil stays in place.
EndoCinch (Bard) Suturing device attaches to end of endoscope. Tissue pinched by suction, and sutures are made by a needle. Idea was abandoned because suction would not be feasible for use over incision. Also, a design that works through the operating port was preferable.
Umbrella Seal Dual umbrella design, one on each side of stomach wall. Umbrellas lock together to seal incision. This idea was chosen for launch. The design was simple and feasible. The device would be similar to heart-patch devices already on the market that work on the same principle.
The Stomach
A B C D
Final Prototype Photos

• Stomach wall incision made in the body of the
  stomach in order to avoid damaging the pacesetter
  cells in the fundus or the muscular antrum.
• Mucosa thickness 1030 130 µm to 1640 80
  µm
• Wall thickness 2.8 0.12 mm to 4.23 0.03
  mm.

Social Impact and Market Potential

1. Outer umbrella (blue) is pushed out of packaging
   sleeve by the pushing/guiding mechanism (green)
   and down the operating port. Umbrella unfolds as
   it emerges from the end of the endoscope and into
   the stomach.
2. Outer umbrella is positioned on the outside of
   the stomach wall. Pushing mechanism is removed
   from operating port. Inner umbrella (red),
   folded inside packaging sleeve is slipped onto
   the guiding wire. It is pushed out of packaging
   sleeve and down the operating port by the pushing
   mechanism. Umbrella unfolds as it emerges from
   the end of the endoscope.
3. Inner umbrella is positioned on the inside of the
   stomach wall. Umbrellas are drawn close together
   using simultaneous pressure from the pushing
   mechanism and tension from the guiding wire.
   Umbrellas clip in place as the center tip of the
   outer umbrella compresses enough to travel
   through the center ring of the inner umbrella.
4. Pushing mechanism is removed from operating port.
   Scissors are used to clip off the guiding wire
   from the outer umbrella as close as possible to
   the center tip. Guiding wire and scissors are
   removed from the operating port.

• The development of this device would make NOTES
  procedures possible, eliminating scarring on the
  abdomen for simple procedures. NOTES might also
  decrease recovery time.
• About 29 of all surgeries worldwide are
  performed endoscopically.
• There are about 80,000 abdominal surgeries
  performed each year in the United States.

Procedures that could be performed using NOTES
Tubal Ligation Cholecystretomy Hysterectomy Splenectomy Appendectomy Gastroenterostomy
Design Development
Ethical Concerns
Design Concern Modification Figure
Endocsope port too small to accommodate spines that pierce thickness of stomach wall. Instead of using spines that traverse stomach wall to clip together, use short spines to dig into stomach wall to keep device in place.
Need a mechanism for opening umbrellas from folded position. Use biomaterial Nitinol it may be folded to fit in endoscope port then spring back into open position upon release.
Need a method to rigidly guide umbrellas in place, then release for implantation. Outer umbrella attached to flexible guiding wire, then pushed into place by a more rigid tube surrounding the guiding wire.
Need a mechanism for clipping umbrellas together once in place. Outer umbrella equipped with center spine that will clip into inner umbrella. Clipping to be accomplished by guiding wire and pushing tube.
Need a material for umbrella covering that will effectively seal the incision. Use biomaterial Surgisis it will cover the hole to prevent leakage, then eventually become built into stomach wall for extra stability.
Do the benefits of NOTES procedures outweigh the
risks? In order to make NOTES procedures
ethically feasible, the closure device must be
reliable enough to reduce the risk of NOTES to
that of laparoscopic procedures.
RECOMMENDATIONS AND CONCLUSION
BIOMATERIALS

• To-scale model We were unable to develop a
  to-scale model because of time constraints and
  lack of resources. For future work, a to-scale
  model should be developed by contracting the
  manufacturing to a company who has the equipment
  needed to build such a small device.
• Testing of our device Due to time
  constraints, we were unable to test our device.
  The next step of the design process would be the
  development of a working model for testing on
  animals. Once this has been accomplished, it can
  then be tested within a clinical trial on humans.
• Biobsorbable Material Our current design is a
  permanent implant by using bioabsorbable
  materials instead of Nitinol, more patients and
  doctors might be willing to use it. Currently,
  Guidant is testing a bioabsorpable drug eluting
  stent that they have developed. If this material
  proves to be successful in this application, if
  could be used within the design of the second
  generation Gastroseal.
• We have developed a device that would work with
  the specified sizes of the endoscope and the
  incision and that would be biocompatible,
  durable, and feasible. We feel that with further
  investigation into bioabsorbable materials and
  testing, our device could be very marketable and
  fill the void that currently exists in the
  development of the NOTES procedure. Ultimately,
  our design provides the opportunity for NOTES to
  become a very successful and popular surgery in
  medicine around the world.

Nitinol
Nitinol is a combination of nickel and titanium
and is a commonly used biocompatible material.
Nitinol has the unique property of thermal shape
memory it becomes very flexible when cooled,
and then returns to its original shape when
warmed. This property makes Nitinol very useful
for devices such as stents and heart patches.
Surgisis
Surgisis (Cook Group, Inc.) is a biomaterial
used for soft tissue grafts. It is a paper-like
material that is a matrix of acellular collagen.
It is often used for hernia repair. When
implanted, Surgisis acts as scaffolding for new
tissue to grow over for remodeling.
For references and citations please see final
report, Appendix F, of Gastroseal Endoluminal
Closure Device by B. Dhillon, A. Hales, L.
Mattaliano and J. Sticklen.