MSI Stent Securement Testing Overview
Summary
TLDRIn this presentation, Melissa Lockwitzer from Machine Solutions discusses the importance of stent securement testing for patient safety and regulatory compliance. She compares three methods—shim, tape, and the MSI SR-1000—evaluating their ease of setup, operation, and data consistency. The SR-1000 stands out for its automation, precision, and reduced variability in results. Lockwitzer highlights how the SR-1000 offers more consistent and efficient testing than traditional methods, emphasizing its advantages in improving stent testing practices. The presentation also includes a demonstration of the SR-1000 in action.
Takeaways
- 🩺 The presentation is by Melissa Lockwitzer, focusing on stent securement testing methods and their importance.
- 🏥 Stent securement testing is crucial for patient safety and is required by the FDA to ensure that stents reach the intended treatment site without issues.
- ⚙️ Three different stent securement methods are compared: the shim method, the tape method, and the SR-1000 by MSI.
- 🔧 The SR-1000 is the most automated of the three methods, launched last year by Machine Solutions (MSI), and features segmental compression technology.
- 📊 The tape method shows the highest standard deviation and requires significant setup time, often leading to misleadingly high retention forces.
- 📉 The SR-1000 had the lowest standard deviation (0.06 lbs) and the most consistent results in terms of stent securement forces.
- ⏳ Setup time comparison: The tape method takes over 6 minutes, the shim method takes around 3 minutes, and the SR-1000 takes only 1 to 1.5 minutes.
- 🔍 The SR-1000 integrates a video system that links to the test data, helping to identify the exact moment of stent dislodgement.
- 📐 The SR-1000 also provides control over diameter and force, minimizing operator variability and ensuring a more accurate stent securement test.
- 🚀 The conclusion suggests that the longstanding belief about minimum retention forces may be based on the outdated tape method and should be reconsidered.
Q & A
What is the primary purpose of stent securement testing?
-The primary purpose of stent securement testing is to ensure that balloon-expandable stents are securely crimped onto the delivery system, making sure they reach the intended treatment site safely and function effectively. This testing is crucial for patient safety, as failure to secure the stent can result in serious complications, including prolonged procedures or even open-heart surgery.
What are the three failure modes discussed in the presentation?
-The three failure modes discussed are: 1) Straight dislodgement, where the stent moves outside the proximal and distal marker bands, causing issues with deployment. 2) Stent compression or buckling, which can cause vessel damage or perforation. 3) Complete dislodgement of the stent, where it detaches from the delivery system and can lead to severe complications such as the need for open-heart surgery.
What are the three methods of stent securement testing compared in the presentation?
-The three methods compared in the presentation are: 1) The shim method, which uses stainless steel shims and an Instron tensile tester. 2) The tape method, which uses adhesive tape to secure the stent. 3) The MSI SR-1000 method, which utilizes segmental compression technology for more automated and controlled testing.
What are some of the challenges associated with the shim method?
-Some challenges with the shim method include difficulties with sample alignment. If the sample isn't perfectly straight, axial angulation can result in higher stent securement forces that are not indicative of the actual securement. Additionally, different-sized shims are required for various stent and balloon sizes, adding complexity to the setup.
Why does the tape method yield the highest securement forces?
-The tape method yields the highest securement forces because the tape often adheres to the balloon underneath the stent in addition to the stent itself. This adhesion increases the perceived securement forces, even though it may not accurately reflect the actual securement of the stent on the balloon.
What are the key advantages of the MSI SR-1000 over the other methods?
-The key advantages of the MSI SR-1000 include a more automated setup that reduces operator variability, the ability to control both the diameter and force applied to the balloon, and a shorter setup time of around one to one and a half minutes per sample. It also provides more consistent and accurate data with lower standard deviation compared to the other methods.
How does the SR-1000 system ensure accurate stent securement testing?
-The SR-1000 system ensures accuracy through its segmental compression technology, which grips the catheter and balloon with precise radial force. It controls both the diameter and the force applied to ensure consistent and linear alignment of the sample, eliminating side axial loading that can skew results. The system is also fully PC-controlled, minimizing operator error.
What were the findings regarding the standard deviation of the securement forces for each method?
-The tape method had the highest standard deviation (0.36 pounds), indicating significant variability in the results. The shim method had a lower standard deviation (0.1 pounds), while the MSI SR-1000 had the smallest standard deviation (0.06 pounds), showing that it produced the most consistent and reliable results.
Why is the video system integrated into the SR-1000 system beneficial?
-The video system integrated into the SR-1000 is beneficial because it allows operators to visually confirm the moment the stent starts to dislodge. This feature is linked to the data in real-time, ensuring accurate identification of the initial dislodgement point, which helps when analyzing forces and ensuring precise testing.
What conclusion was drawn about the commonly accepted minimum retention force of 0.5 to 1 pound?
-The presentation concludes that the long-standing notion of a minimum retention force of 0.5 to 1 pound may be based on the tape method, which produces artificially high securement forces. This standard should not necessarily be applied to other methods, like the MSI SR-1000 or the shim method, which provide more accurate measures of stent securement.
Outlines
🎤 Introduction and Background
Melissa Lockwitzer introduces herself and her presentation on stent securement testing. She provides an overview of her background in biomedical engineering and her role at Machine Solutions, a leader in medical device manufacturing and testing. She also mentions her work with ASTM subcommittee fo4.30.06, which developed the standard for stent securement testing. The introduction highlights the importance of stent securement testing for patient safety and the need for compliance with FDA requirements.
🛠 Methods of Stent Securement Testing
Lockwitzer describes the three methods of stent securement testing: the shim method, tape method, and MSI's SR-1000 system. She explains how each method works, focusing on ease of setup, operation, and output variability. The shim method uses stainless steel shims and Instron tensile testers, while the tape method involves adhesive tape to secure the stent. MSI's SR-1000 is the most automated system, utilizing segmental compression technology for more precise and consistent testing.
📏 Shim and Tape Methods Explained
A detailed look at the shim and tape methods, including their challenges and setup processes. Lockwitzer explains the specifics of the shim method, which uses stainless steel shims and the ASTM guidance document f2394-07 for stent testing. She also highlights the difficulties with axial angulation in the setup, which can lead to higher stent securement forces. The tape method is discussed in detail, explaining the labor-intensive process of cutting and placing the tape precisely, the challenges in preventing tape adhesion to the balloon, and the use of standard Instron tensile testers to pull the stent.
🔧 The MSI SR-1000 System
Lockwitzer describes how the SR-1000 system from MSI works in comparison to the other methods. This fully integrated system uses motors, load cells, and software to automate the stent securement process. It allows for precise diameter and force control, making the process more consistent. She explains how the system measures withdrawal force and distance and highlights the advantages of the SR-1000, such as the built-in video system, which records the exact moment the stent moves, correlating it with force data.
📊 Test Results and Observations
A comparison of test results from the three stent securement methods shows that the tape method has the highest standard deviation, while the SR-1000 provides the lowest variability. The tape method yields higher retention forces, but these are attributed to the tape's adhesion to the balloon, which causes misleading results. Lockwitzer emphasizes the SR-1000's advantages, such as reduced setup time and greater consistency across samples, due to its automated process and integrated video system.
🔍 Analyzing the Results
Lockwitzer discusses the reasons behind the variability in the test results, noting that the tape method's high variability is due to inconsistent adhesion to the balloon. She also notes that the time-consuming nature of the tape method and the non-circular opening of the shim method contribute to higher forces and variability in those methods. She concludes that the SR-1000 system reduces operator variability and provides more accurate results due to its precise control of force and diameter.
🏆 Key Conclusions and SR-1000 Advantages
The presentation concludes with key findings, suggesting that long-standing industry standards for stent securement forces might be based on outdated methods like the tape method. Lockwitzer suggests that the SR-1000 system, with its lower variability and simpler setup, offers a more accurate and efficient way of testing stent securement. She emphasizes that MSI's SR-1000 eliminates operator variability, ensures linearity, and offers precise control, making it the preferred method for stent securement testing.
📹 Demonstration of SR-1000 System
Lockwitzer wraps up her presentation by offering a video demonstration of the SR-1000 system in action. The video showcases the system's precise control over grip force, diameter, and pull distance, illustrating the dislodgement of the stent and how the data is captured. She invites attendees to visit the booth for a live demonstration and encourages further questions about the system.
Mindmap
Keywords
💡Stent securement testing
💡Dislodgement
💡Shim method
💡Tape method
💡SR-1000
💡ASTM guidance
💡Segmental compression technology
💡Initial dislodgement force
💡Crimping
💡Standard deviation
Highlights
Introduction to stent securement testing and its importance for patient safety.
Melissa Lockwitzer presents her background in biomedical engineering and experience in medical device testing.
Machine Solutions (MSI) as the global leader in medical device manufacturing and testing equipment.
Stent securement testing is required by the FDA, but its main importance is ensuring the stent reaches its treatment site safely.
Three main failure modes of stents: straight dislodgement, stent compression/buckling, and complete dislodgement.
MSI conducted a comparison test of three methods of stent securement testing: shim method, tape method, and MSI's SR-1000.
MSI's SR-1000 is the most automated of the stent securement methods, offering precise control and ease of use.
Shim method involves thin stainless steel shims and an Instron tensile tester, with challenges around sample angulation.
Tape method, while widely used, involves adhesive tape and presents significant variability in results due to tape adhesion to the balloon.
MSI SR-1000 uses segmental compression technology to provide consistent radial gripping, resulting in lower variability and more accurate data.
Testing showed that the tape method had the largest standard deviation, while MSI's SR-1000 had the smallest.
The SR-1000’s design reduces operator variability through force and diameter control.
SR-1000 integrates a video system for real-time monitoring and data synchronization, allowing precise identification of initial dislodgement.
The study revealed that industry assumptions about securement forces may be based on outdated methods like the tape method.
MSI's SR-1000 offers the fastest setup time, taking only about one to one-and-a-half minutes per sample compared to six minutes for the tape method.
Transcripts
welcome everyone
i am melissa lockwitzer and today i'm
presenting the ins and outs of stent
securement testing
thank you very much for coming and
listening to this presentation
so we'll start over with a bit of an
overview
so i'll give you some background on
myself as well as machine solutions
the importance of stem securement
testing
and then what we did
to compare three different stent
securement type methods to really kind
of give you an overview of what sten
securement is out there today as well as
where msi plans to take it in the future
so my background i have my master's in
biomedical engineering and i've worked
in the medical device industry for eight
years
still in the
industry today
manager of the contract testing lab at
machine solutions as well as other
responsibilities
and i'm a member of the astm
subcommittee the fo4.30.06
this is a subcommittee that actually
wrote the standard
the guidance on stent securement
and recently i led the development team
for msi's current extend securement test
system the sr-1000
so a little bit about machine solutions
we are the global leader in medical
device manufacturing and testing
equipment
we have a wide range of products from
stent crimping
self-expanding stent loading
angioplasty balloon pleating and folding
device testing equipment the sr1000
which i'll talk more about today
so what's so important about stent
securement testing
one of the key things is the fda
requires it um but but more important i
think to me than that is it's it's
important for patient safety um the
purpose of the testing is to verify that
you know the balloon expandable stent
that's crimped on that delivery system
makes it to the intended treatment site
in a very functioning and safe way
so what sten securement looks for
there's a few failure modes
three that we're looking at here
one is a straight dislodgement
so if you look at the image on top here
basically this is when the stent moves
outside of the proximal and distal
marker bands those marker bands are what
the physicians use to position that
stent and if that scent moves outside of
that window there's going to be an issue
with
complete deployment of that stent
and if that happens the doctor's then
going to have to take significantly more
time to attempt to deploy that stent in
a different manner
another failure mode is stent
compression or buckling
and that's
pictured here
definitely wouldn't want that pressed up
against my vessel wall
it's something that will
with those struts being perpendicular to
the plane of the stent you're going to
end up possibly with perforation into
your vessel wall and definitely damage
in a longer healing time for that
procedure
then the kind of worst case scenario is
a complete dislodgement of the stent
that stent fully comes off of your
delivery system and embolizes into your
system now you're potentially looking at
open heart surgery to retrieve that
stent um
and definitely a significantly longer
recovery time than what you're planning
on
so the comparison test what we did at
msi was we conducted a test to compare
three methods of stent securement
testing the shim method the tape method
and msi's sr1000
the purpose was to look at the ease of
method setup
ease of operation as well as output
variability
the sr-1000 was launched last year by
msi and is the most automated of the
methods
both the shim and tape method have been
in use for many years within industry
and are currently in use today as well
so some images of the test methods
shim and instron
the shim sorry
the shim method which utilizes the
instron tensile tester this is a method
that uses thin stainless steel shims
and instrument
standard grippers to withdraw the
balloon from
the stent the tape method
it's as as basic as it sounds you see
two pieces of adhesive tape uh generally
painters type tape
and they're used to secure to the stent
and standard in strong grippers are used
to grip your
catheter as well as the tape and
dislodge the tape and stent
from the balloon
then you have the msi sr 1000 this uses
our segmental compression technology
just in a little different way so we
have two segmental compression heads one
acts as the gripper so you get a nice
radial grip on your
catheter and the other one acts as the
shim
and then the two heads are separated by
a motor to dislodge the stand
i'll get into more detail here as well
so some close-up images of the shim
method
this kind of
this fixture is designed around the astm
guidance document f2
f2394-07
and it is just a guidance document and
the shim method is one of the
methods that is just a possible
test method within that
so you have
two 5000 stainless steel shims these
have rounded v-notches
and that's what contacts the
circumference of the stent's proximal
edge
and you have to have different
you have to have different size shims
for all of your different size stents
and bloom systems
and
um along with instant system to support
the custom base
and withdraw so
some of the other challenges uh with
this method set up
so on this image you can see our balloon
and stent are below and then our
catheter is above and this is where our
grips from the instrument come down
if this sample isn't perfectly straight
if it has any kind of axial angulation
to it you're going to get higher
stent securement forces
that aren't actually related to the the
stent being secure onto the balloon
then you have the tape method
uh this uses two pieces of adhesive tape
a lot of times just a painters grade of
tape
a lot of
effort is put into cutting the tape to
the exact length of the stent
so as you can see in this image
my proximal edge of the stent ends right
at the edge of the tape distal end right
at the edge of the tape you can see it
here as well
this is the edge of my stent
and then we create two tabs
these two tabs are just folded over a
piece of tape so we're actually grabbing
onto the tabs and we want to prevent any
of the tape from adhering to either the
proximal or distal edge of the balloon
we also use a clam shell fixture so we
need to basically stick the tape to the
stent without actually compressing it
with our hands or in a non-circular
fashion because we don't want to change
how that stem stem's been crimped before
we do our testing so
we have multiple clam shells that are
have radiuses sized to the stent plus
the thickness of the tape
so that we can place the tape in the
clamshell the stent on top tape on top
of that
close the clam shell and try to secure
the tape or secure the tape just to the
stent and not to the balloon
well um if the stent has been probably
properly secured onto the balloon you
have parts of that balloon that stick up
and it's very hard to prevent um the
stent or the tape from sticking to that
balloon that's right underneath the
stent itself
we use a standard instron pencil tester
with two standard grips to dislodge the
stent and tape and hold on to the
catheter
significant patience was needed with
this method it was the longest
setup per device it took over six
minutes to get everything set up just
right um to be able to get as clean a
data as we possibly could with this
method
segmental compression so msi's sr1000
so with this method we have it's a fully
contained system has the motors load
cells
and the software all incorporated into
the system
the segmental
compression head that has one millimeter
thick segments that acts as your shims
and it has diameter and force control so
you can close down that head to a set
diameter
as well as knowing exactly how much
force you're applying to the balloon
just distal to that stent
the additional set of
segments is used to grip and then we
have a motor
and load cell here that are used to
separate those two and measure your
withdrawal and force as well as the
withdrawal distance
another nice feature with the sr 1000 is
the integrated a video system with the
data
sometimes if you can see on this graph
your securement data is very obvious
this is your initial dislodgement point
but sometimes it's not quite as obvious
and having that video linked in time
allows you to see exactly when that
stent started to move and compare that
to where your data
where the forces are at on your data
test samples and preconditioning so we
use 30 stainless steel balloon
expandable stents
just a standard 3.5 millimeter od by 24
millimeter length
we crimped them on to pleated and folded
balloons
using the msi sc775 this system allows
us to crimp to a force while imparting
heat and pressure into the balloon
that pressure within the balloon
while we're crimping down to force
allows that balloon to kind of expand
slightly underneath that stent and get
into any of kind of the between struts
um or between segments so that you get a
very tight securement of that
stent after we crimped the stents outer
diameters were measured to make sure all
30 samples um were identical before they
were randomized into the three different
groups we had a standard deviation of
less than one thousandth of an inch
for our final ods
the samples were not tracked through a
torturous path
as the astm standard calls out they were
soaked in a water bath we opted to not
track them for this testing just that we
could maintain as uniform as possible
samples
as soon as they get tracked there may
have been slight
differences in the stents and because we
were just looking at comparing the three
methods and not actually you know
testing actual securement or
wanting to submit this data we
chose to not track the samples
so the test parameters we tried to keep
everything as similar as we could
between the three methods one of those
similarities was the pull rate so 10
inch per minute this is based on the
guidance document
the shim size
was
36th out of 46 thou
because they're slightly oval
and non-circular that was the diameter
range for those
the sr-1000 capture diameter
was one millimeter with a capture force
of one newton plus or minus 0.2 so we
actually can know what force we're
applying on that balloon
and the pull distance was set to 10
millimeters for all of the methods
so the results the exciting part here so
there we go i got a smile
we have 10 stents that were tested with
each method the graph shows the
initial dislodgement force in pounds
the blue is the sr 1000 data the red is
the shim data and the green is the tape
method
as you can
really obviously see the tape method had
the largest standard deviation
0.36 pounds
the shim method was a little tighter on
the standard deviation 0.1
msi was below 0.1 at 0.06 pounds
but you also see along with the
i guess large difference in standard
deviations is the large difference in
your actual state retention forces we're
looking at an average of two pounds for
the tape method
0.5 pounds for the shim and about 0.25
for the sr-1000
so really wanting to look at
what causes you know those
dramatic differences i guess
statistically difference uh
statistically significant differences um
in data
so before we touch on that um just
wanted to highlight how that initial
dislodgement force was pulled from the
data um it was actually fairly simple
with this group of stents we just looked
at the peak before
a drop in force was shown
so as you can see here this was actually
a lateral move so we actually kept going
up right here was our peak force before
we saw a drop in force and so that would
be our initial dislodgement force
there can be higher forces
farther along in the data and that may
be from the stent going over a distal
seal a marker band or other feature on
the balloon that's meant to secure it
that may cause higher forces
so in comparing these three methods with
this close to identical devices as
possible it's a destructive test so you
can't use the same sample over and over
again
the difference is definitely
statistically significant
the tape method yield the highest forces
but that's most likely due to the tape's
adhesion to the balloon beneath the
stent as well as the stent itself no
matter how much we try to gently
compress that tape onto that stent you
just can't avoid that that adhesion
there
as well as the variation in the tape
adhesion to the balloon there might be a
little more balloon sticking out on some
stents than on others and as soon as
different amounts of balloon are adhered
to the tape you're going to have
a great variation in actual your
securement data
the tape method was also the most time
consuming if you compare the three
methods the tape method took upward of
six minutes per sample to set up the
shim method was seated in about three
minutes per sample to set up and the sr
1000 was at a minute to a minute and a
half to set up for each sample
the non-circular opening of the rounded
v-notches on the shim method
really can be attributed to the slightly
higher forces with that method
not knowing exactly how much compression
you're getting on that balloon and
depending on the pleat and fold of that
balloon
as well as slight angulations in our
setup definitely led to more variation
and higher forces within that method
so some key conclusions i guess from
this data the long-standing notion that
the minimum retention force of a half to
one pound for a secured device
may truly be based on the tape method
and should not be applied to other
methods of stent securement testing um
for a long time when we looked at sense
securement data and saw forces below a
half a pound we're like oh that's you
know not a very secure device but i
think it just really depends on the
method that you're using to secure that
to test that securement
the standard deviation within the tape
as well as those misleading high values
should really put this method into
question and the sr-1000 produced very
similar results to the the shim it had a
simpler setup and you could use the same
setup for a wide range of your diameters
and the smaller standard deviation
highlights its innovative qualities
so some of the features that
msi put in to the sr 1000 to
eliminate some some of that variation
we really wanted to eliminate operator
setup variable thus putting in the
diameter control as well as the force
control
the key with the two sets of segmental
head it keeps those two heads concentric
so when you close down on your grip and
you close down on your capture that
sample in there is always linear you're
not going to have any other side axial
loading to add variability to your data
we have a very short gauge length that
we can use on our system it prevents
stretch effect of the catheter we're
pulling a polymer
if there's any stretch within that
sample that's going to lead to some
variation in your data
and then also the system just being pc
controlled all of the force and diameter
calibrations are simply done within the
system leads to a lot of
eliminates a lot of operator variability
the sr-1000
it can be kind of a little harder for
you guys to visualize you may not be as
familiar with it
the tape and shim are out there so i did
want to show you a video today just to
allow you to kind of see
um
oops sorry let me pop back
there we go
just so you can see how the sr-1000
works we also have this system at our
booth so if you want a live
demonstration please stop by our booth
so this is the
the grip side of the segments closing
down on your catheter shaft
so we usually set this just to a grip of
20 newtons just so we have a strong hold
this is the one millimeter
shim segment
closing down to a set diameter or a set
force
now you can see the two segments
this is your grip and this is your shim
and now you can see the stent
initial dislodgement as it pulls in
within the software
you have full control of your closed
diameter closed speed your pull speed
as well as your grip force
and your pull distance in this study we
did the 10 millimeter length pull
the most interesting information
generally does occur within this first
one millimeter of the pull
but sometimes it's you know just
beneficial to see what's also happening
as it's going over your distal seal or
other features of your balloon as it
gets withdrawn into your stent
and so it's nice to have both this video
and data are then linked in time
so if your operator may have missed when
that initial dislodgement happened they
can go back and pull up that video and
find that force
that they need for their
submittal
so that's uh concludes my presentation
today but if there's any questions i'd
be happy to take them now or you can
stop by our booth 3135 and i can take
questions there as well
thank you very much for your time and
attention today
you
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