Bypass surgery made easier

By: 
January 06, 1997
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Timeline
October 1994Surgeons gather at Ethicon
Endo-Surgery to relate concerns about open vein harvesting
January/ February 1995
Another surgeon panel meeting
called to review progress since the earlier session.
March 1995 Project business plan completed.
May 1995 Team starts to develop dissector, retractor, and
vessel dissector instruments and the procedure for their use.
August 1995 Team split off to develop the medium clip applier.

March 1996 First deliveries made of the dissector, retractor,
and vessel dissector.
April 1996 Market release of vessel harvest kit.
November 1996
Medium clip applier introduced to the
market.
How vein harvesting works
- Surgeon introduces the ENDOPATH Subcu-Dissector in the incision to
create the operative space (tunnel) in the subcutaneous tissue of the leg,
while viewing the procedure via the endoscope and video camera.

-
ENDOPATH Subcu-Retractor also inserted through the incision to maintain
the operative space around the vein to be harvested, again viewing the
procedure via the endoscope and video camera.

- Vessel Dissector
employed to dissect the tissue and branch veins around the vein to be
harvested.

- Allport Clip Applier used to hold and apply clips to
the accessory veins following dissection.
Design considerations and solutions
- Problem: Designing instruments to use with
endoscopic equipment that would harvest veins for coronary bypass surgery
by making only a few small incisions.

- Objective:
To reduce the long surgical incision typically made to retrieve the
vein.

- Solutions: Meeting with a surgical panel
to uncover the problems encountered with the long surgical procedure and
how they might be overcome.

Putting together a business plan and
design team to implement the project, including the decision to produce a
disposable rather than a reusable system.

Designing the four
instruments for the vein harvesting procedure in record
time.

Testing the system and obtaining fast approval from the FDA
for its use.
Commercializing the system before the competition.

Cincinnati,
OH
--Thanks to an 18-member development team at Ethicon Endo-Surgery Inc.
(EES), a Johnson & Johnson Co.,
patients now have an alternative to the long incision typically used to extract
veins for coronary heart bypass surgery. The vein harvesting operation normally
takes place simultaneously with the coronary bypass operation.

The new procedure designed by the EES team, called the EndopathTM
system, consists of four primary devices that physicians can employ in
conjunction with an endoscope:

- Subcu-Dissector(R), used to create operative space (tunnel) in the
subcutaneous tissue of the leg.

- Subcu-Retractor(R), used to maintain the operative space.

- Vessel Dissector(R), used in the blunt dissection of tissues.

- Allport Clip Applier(R), used to clip the vein branches following
dissection.

"Our innovative devices will revolutionize this surgical procedure," boasts
John Love, project team leader for the EES team that developed the vessel
harvest instruments.

The EES team performed this achievement in a "record time" of 18 months from
initial discussions to market. Critical to the design of the devices was
materials selection. Therefore, early in the design process, the engineering
team got valuable "in-house" assistance from Dow Plastics, Midland, MI.

Visitors to the Medical Design and Manufacturing West show to be held next
month (Feb. 11-13) in Anaheim, CA, can view the system first-hand at Dow
Plastic's Booth 1047.

Powerful potential. The importance of the new system cannot
be underestimated. From 550,000 to 600,000 patients worldwide undergo coronary
artery bypass grafting each year. The worst pain for some patients who face the
surgery is actually in the leg, from which the surgeons remove a vein to bypass
the diseased coronary arteries.

The vein harvesting project began in October 1994 when three different groups
of customers came to EES to voice their dissatisfaction about the current vein
harvesting methods, according to Michael F. Clem, EES's manager of emerging
surgical procedures. "There are sometimes clinical complications in the way
saphenous vein harvesting is done today, which is a single, long incision down
the leg," says Clem, a doctor of veterinary medicine, summing up the group's
concern. Among the customers were plastic surgeons, peripheral vascular
surgeons, and a general surgeon.

Their concerns were reinforced by the addition of cardiovascular surgeons and
surgical assistants to the group. The meetings helped define what the
difficulties of the vein harvest procedure were, followed by brainstorming
sessions to outline possible solutions.

Clem adds that the project involved much more than the financial reward that
might ensue for EES. "We wanted to look at it from the standpoint of caring
about the patient," he explains. "We were informed that about 10% of patients
who undergo open vein surgery suffer from major complications." Depending on who
you talk to, complications can involve as few as 1% of the patients treated to
more than 40%.

One of the problems is that after a four- or five-day stay at the hospital,
the surgeons send the patients home. A week later, when they go back to their
cardiologist or general-practice physician, complications can show up. "My
understanding is that a lot of these complications occur after discharge," says
Clem.

Before investing in the project, EES looked carefully at the business
potential, costs, and patient benefits involved with designing a new vein
harvesting procedure. Study results looked promising.

With this incentive as a positive driving force, EES decided to give the
project the go ahead. Enter Gary Knight, EES senior design engineer, as project
leader. In the lab and at the model shop, Knight and Clem, plus Steve Black,
model maker at EES, developed several system prototypes. The goal, says Knight,
was to create a new prototype every week. "We pretty much hit that mark on
average over the next three months," Knight recalls.

Helping to make this possible were assists from EES's 3-D CAD solid-modeling
programs and 3-D rapid prototyping. For this project, the designers relied on
Pro/ENGINEER from Parametric Technology Corp., Waltham, MA, to design the
models. (EES is in the midst of switching to Milford, OH-based SDRC's I-DEAS
software
.)

"Once the solid models were iterated, we turned the CAD files over to Steve
and our model shop to produce the sterolithographic models," Knight notes.
"Within a week's time we were able to go from an idea on paper to molded
urethane parts using 3-D CAD, SLA (3D Systems, Valencia, CA), or SLS (DTM Corp., Austin, TX), and
rubber molds."

Disposability decisions. Serious discussions ensued during
the design stages as to whether or not to make the instruments reusable or
disposable. With medical costs continuing to spiral, hospitals are looking for
ways to cut expenses wherever possible, especially in the operating room. Some
panel members considered that the ability to reuse the vein-harvesting equipment
would cut costs, as well as be more environmentally sound.

However, a reusable device also has some drawbacks. For instance, the initial
cost of reusable devices is significant, and resterilization and repackaging
would have to be included. And, a reusable device would make the design far less
flexible when adding improvements to the instruments. In addition, all materials
used in a disposable system are environmentally sound and can be incinerated in
the typical fashion.

The decision: make them single-use, disposal devices.

As noted, the vein harvesting procedure works in conjunction with an
endoscope. In a typical operating-room setting, the endoscopic equipment
encompasses a one-chip or newer three-chip camera; a 5 mm x 300 mm, 30-degree
endoscope; fiber-optic light source; and video equipment that lets the surgeon
follow the path of the endoscope as it travels along the route of the vein,
while also providing a video record of the procedure.

Materials input. Karen L. Winkler, senior applications
development engineer at Dow Plastics, helped the EES engineers work through the
intricacies of materials selection.

The discussions entailed how best to incorporate standard engineering
plastics in products that compete in a high-end, value-driven business. Criteria
behind the choice also included the need for a rigid material that could
withstand stress under operating conditions, as well as one that would easily
flow into the 20-inch mold and properly free the ribbed construction of the
handles. Moreover, the materials had to stand up to gamma radiation and ethylene
oxide sterilization procedures.

In sessions with Knight; Dave Stefanchick, staff design engineer; and James
L. Millward, EES' supplier manager-material technology--and using results from
mold-flow analyses--the team settled on four Dow materials:

- Isoplast(R) 2540 40% glass-filled thermoplastic urethane for the vessel
dissector's 20-inch-long, gray rod.

- Calibre(R) 5201 20% glass-filled polycarbonate for the clip applier's,
dissector's, and retractor's white handles and cover.

- Calibre MegaRad(R) 2081 clear-grade polycarbonate for the dissector's
and retractor's blunt-tip spoon, allowing the surgeon to view the endoscopy as
the device tunnels its way along the vein.

- Pellethane(R) 2363 80A thermoplastic polyurethane elastomer for a scope
retaining clip that permits most en-doscopic devices to be inserted intoeach
instrument's handle.

Each instrument's shaft and the ferrule that holds the assembly together
consist of 304 stainless steel.

Clear-cut decision. EES got FDA clearance to market the
system last February. A few weeks later, the Louisville-based Jewish Hospital
became the first facility in the nation to remove a vein through the new
videoscopic procedure. The hospital is the 8th largest heart center
out of 850 across the U.S.

As of last count, more than 2,000 such operations have been performed at 100
hospitals since the system was introduced. Many others are joining the fold all
the time, EES officials note. As the procedure becomes more readily available,
"more patients will be pressuring their doctors to adopt the new harvesting
method," asserts Dr. W. Peter Geis, director of the Minimally Invasive Surgical
Training Institute at Baltimore's St. Joseph Medical Center.

Both surgeons and the EES team members see the cost and time to perform the
procedure shrinking as more of the devices enter the market and more surgical
personnel are trained in their use. For example, it takes 30 to 45 minutes to
perform the open leg surgery, and could take as much as an hour to close the
incision.

The procedure also gets high marks from Dr. Peter P. McKeown, associate
professor of surgery at the University of South Florida College of Medicine in
Tampa, who was one of the first to perform the operation. He feels the procedure
"will become the standard of care in one or two years." And that forecast should
be welcome news for the hundreds of thousands of future patients who face
coronary artery bypass surgery.

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