Abstract

1
Abstract
Market Analysis Patent

• Market
• Children birth 15 years
• Adults varying in ages
• Projected sales
• Year 1 2.7 million
• Year 5 3.6 million
• Selling price of PDA device 200
• Costs of goods sold per device
• Polyurethane foam 3.25
• Nitinol wire 0.90
• Manufacturing costs 12.00
• Manufacture insurance 36.00
• Incremental cost 85.00

Design Refinement Tests After several
brainstorming sessions and Internet searches of
current occluders, a design similar to last years
group was decided upon. A mushroom shaped foam
would yield flexibility that could conform to PDA
shapes, with a Nitinol wire backbone to infuse
strength and support. Fig. 3 shows a rendering
of the conceptual design decided upon at the
brainstorming sessions. Two separate tests were
conducted to ensure proper functioning of the
device design. First, it was necessary to
ensure that the foam plug could withstand a
maximum pressure difference of 100 mmHg using
tubing and a column of water. Second, a flow
test using an in-vitro PDA simulation was
conducted to determine if the device would indeed
occlude the flow between the pulmonary artery and
aorta. Search for Materials Several epistaxis
strip producers were contacted about using their
foam, with little success. Most makers of
biocompatible foams will not certify their foam
for use in the body, thus few commercial foams
were available. A materials expert in Florida
was able to outline the steps and chemicals
necessary to manufacture a biocompatible foam
independently. One particular chemical proved
impossible to procure by students. The Nitinol
memory wire was easy to secure and relatively
inexpensive. Thus, for testing purposes, generic
foam was used with copper wire.
Patent ductus arteriosus is the persistence after
birth of an in-utero shunt from the pulmonary
artery to the aorta. To correct this deficiency,
an elective procedure is performed at five to ten
years of age to close the hole. Current treatment
involves catheter insertion of fibrous coils into
the duct, relying on endothelialization to
completely occlude flow. This project sought to
build on two previous groups efforts to design an
alternative closure device. Biocompatible
materials were investigated, a prototype built,
and tests performed to measure the effectiveness
of the design. A polymer specialty firm was
contacted to make a certified prototype and
preliminary work has been completed in the
application for a patent.

• Patent fees 20,000
• In process of filing preliminary patent with
  Office of Technology Transfer

Patent ductus arteriosus (PDA) is the persistence
of a normal fetal structure between the left
pulmonary artery and the descending aorta.
Persistence of this fetal structure beyond 18
days of life is considered abnormal. This
condition accounts for 10-12 of all congenital
defects and has an estimated incidence of more
than 20,000 cases in the United States alone. It
is responsible for many adverse effects including
growth retardation, breathlessness, lack of
appetite, bacterial endocarditis, and congestive
heart failure. Multiple treatments have been
developed for PDA, including drug therapy
(indomethacin), invasive surgical ligation and
transcatheter implantable devices. The most
common devices used to date are the Cook Coils
and the Amplatzer Duct Occluder (ADO) (Figs. 1
2). A major disadvantage of these methods is
being thick and rigid, forcing the PDA to
conform to their shape, causing undesirable
stress and tension on the walls of the PDA.
Thus, the demand remains for a cost-effective
device that can be delivered through a small
catheter and successfully occlude the PDA.

• Refinement of this device to its current design
  provides much potential for successful occlusion
  of PDA
• Using available resources, we have reached the
  final stages of this design process and must now
  resort to a third party for future development
• Quality control requires a sterile building and
  manufacturing for actual implantation in future
  testing
• To complete design process, third party support
  must be obtained for improved facilities and
  additional expenses

• Work with PTG, Inc to build and manufacture
  device prototype of correct size, shape and
  biomaterials
• Obtain IRB approval for animal testing of this
  device on canines
• Work with VUMC Cardiology Department to begin
  animal testing
• Produce finalized design drawings for patent
  filing and continue work with Office of Tech
  Transfer
• Run final in vitro tests using canine blood as
  opposed to water
• Continue to refine design based upon strength and
  durability test results

• In-vitro testing (Fig. 4 Fig. 5) demonstrated
  that water would slowly move through the device,
  however the flow should be minimized in the body
  due to the thrombogenic nature of the blood.
• Pressure testing also yielded promising results
  with the foam device. Leakage did occur, but the
  device was not dislodged by the pressure.
• Two prototypes were built, reflecting the stages
  of design. First, a clay model was built to
  determine the proportions of the materials and
  aid in discussions (Fig. 6). Second, a silicone
  device was made with a wire wrap backbone to
  simulate the size and structure of the final
  design (Fig. 7).

Fig 4. Close-up of PDA Simulation

• It was determined that the Patent Ductus
  Arteriosus Occlusion Device must meet the
  following conditions
• Made from biocompatible materials
• Conforms to the shape of the PDA and causes
  occlusion
• Be delivered via a catheter lt2mm in diameter
  (6-7F)
• Provide an initial success rate of 100
• Quick endotheliazation (1 month)
• Can be easily repositioned
• Cost effective (lt200)
• Simple implantation system
• More patient friendly