0:00

So what is a catheter?

0:02

A catheter is essentially a device that allows

0:05

us to access vessels and structures of choice.

0:11

Here we see what we call a Michelson

0:13

catheter, very characteristic in shape,

0:16

accessing or catheterizing the right

0:18

intercostal bronchial artery trunk,

0:21

okay, usually occurring between T5 and T9.

0:24

And this little guy shows a little

0:26

bit of neovascularity in this

0:27

patient who presented with what?

0:29

Hemoptysis in the setting of cystic fibrosis.

0:32

So this catheter allows us to get in,

0:34

to allow us to do our job, which then involves

0:36

us sending a micro catheter to embolize this

0:39

neovascular hypervascularity in this case.

0:41

But oftentimes catheters can be

0:43

used as flush catheters to take sort

0:46

of high volume sort of pictures.

0:48

They can be used intracerebrally.

0:50

They can be used as a guiding catheter.

0:53

Or they can have multiple purposes.

0:55

So when we're thinking about catheters,

0:56

we think about the components, the Teflon,

0:59

the PTFE, that has a lower coefficient of friction.

1:03

We think about the stiffness that

1:05

Teflon offers, which makes it ideal for

1:07

traversing tight tissue planes or stenoses.

1:10

Then we think about the corollary,

1:12

the polyethylene-made catheters that are soft,

1:15

minimal injury to endothelial tissue, ideal

1:18

for subintimal recanalization.

1:21

And then of course now we have nylon,

1:22

which has nice, solid tensile strength.

1:25

That allows them to accept a little bit

1:27

of higher pressures without rupture.

1:30

Okay?

1:30

It allows the nylon catheters to

1:32

develop a little bit of

1:34

optimum service and support as diagnostic

1:37

catheters or for angioplasty below.

1:40

Okay?

1:40

So every component is the seed of a benefit.

1:45

So, how do we measure the size of catheters?

1:49

Here we see a catheter, a base

1:50

catheter, okay, in this case.

1:52

A Cobra catheter parked at the origin of the

1:56

superior mesenteric artery, five French catheter.

1:58

And then we have a microcatheter that is

2:01

now coaxially passing through the images

2:04

of a bleed in this patient with a GI bleed,

2:07

2.4 French microcatheter, selecting an AL

2:09

branch in this patient with a GI bleed.

2:12

So catheters can be the base and

2:15

then you can have this sort of

2:16

coaxial passing microcatheter. The

2:20

French system is really one of the things that

2:22

allows us to compare the sizes or calibers of the

2:26

catheters we're using. And what's a French? A French

2:29

actually equals a third of a millimeter

2:32

or 0.33. So one French equals a third of a

2:35

millimeter. When we're talking about wires,

2:37

we refer to them in terms of inches: 0.018 inch microwire, 0.035 inch working wire.

2:46

If we're talking about sheaths and

2:50

catheters, we use French, which as we

2:54

know, is in millimeters.

2:59

So one of the things that I think is very

3:00

important is to understand that once you get a

3:02

catheter, you want to always flush it to make sure

3:06

that if it's hydrophilic, which it more often than

3:09

not is, it allows you to move the catheter

3:12

more freely through the body and over the wire.

3:15

It also prevents thrombus formation.

3:18

And one of the things that I think

3:19

deserves to be noted is that you don't want to

3:21

bend or fold the catheter because oftentimes,

3:24

it has the memory that it was designed

3:27

to have, and that memory is very specific.

3:30

And also, depending on the material that was

3:32

used to make that catheter, it may be a little

3:34

soft, and that bend may actually result in

3:38

a weak point, resulting in fracture in the

3:40

human body, which we certainly don't want.

3:43

What's a guidewire?

3:44

A guidewire? It's a nice,

3:46

long, flexible, coiled spring.

3:49

For the most part, to position the

3:51

catheter, as I mentioned, and I like to

3:53

say it's the railroad, okay, it's the

3:54

rail system that you create in the body.

3:58

You know, when you send this little railroad

4:00

through the body, your whole goal is to send it

4:04

where you want it to be, and that then allows

4:06

you to sort of railroad a catheter over it.

4:08

This one is a mandrel, core of a guidewire,

4:11

which can be nitinol or stainless steel.

4:13

Okay, you have a coil spring that is sort

4:16

of wound around that; it's an outer portion.

4:18

These may actually be gold, and they may often

4:22

have a little distal tip that's radiopaque that

4:24

allows you to visualize it a little better.

4:26

And you know, for the most part, wires can be

4:29

hydrophobic, so, you know, not really into the

4:32

whole water situation, you know, or hydrophilic.

4:35

Really all about that high

4:36

affinity water-loving business.

4:38

And so when you think of a coil spring.

4:41

That portion of the microaxis wire often catches

4:43

the bevel edge of a needle as it's removed.

4:46

So sometimes it's important to ensure that

4:48

when you're deciding that, oh, you know, I

4:50

can't really catheterize a wire, you know,

4:53

sort of this area that I'm trying to wire here.

4:55

You're placing a cath, a wire, sort of through

4:57

the transitional dilator and it's not going,

4:59

you know, it's best to, sort of, instead of

5:02

trying to pull it out, you know, through the

5:05

needle, to pull the needle out with it as a

5:08

unit and then hold pressure because you may

5:10

actually sort of break and fracture that little

5:13

transition point and end up sort of leaving that

5:15

in the patient, which would be bad news bears.

5:18

Okay?

5:19

So, let's transition.

5:21

Wires are really sort of the

5:22

next topic of discussion.

5:25

When you talk about wires, they

5:27

come in different shapes, sizes, and

5:29

characteristics to support those functions.

5:32

And so we have access wires that

5:33

facilitate access to a vessel.

5:35

We have wires that allow us

5:36

to maneuver and navigate.

5:39

You know, in select vessels, and these are often

5:41

hydrophilic in nature and a little bit less stiff.

5:43

Kind of can navigate the areas throughout

5:46

the human body and the vasculature.

5:48

Then you have ones that are good as a rail.

5:50

Okay, good support wires.

5:52

They facilitate sort of balloon support,

5:54

stent deployment, catheter exchanges,

5:58

tube placement in the case of sort of non

6:00

vascular cases, and other line placements.

6:04

And so when we're talking about

6:05

wires, we want to think about the

6:06

diameter, the length, and the coating.

6:12

Very, very, very, very important.

6:14

Basic characteristics.

6:16

The other thing that typically is sort of talked

6:18

about, depending on the wire, is the taper length.

6:21

Some wires have a long, tapered

6:24

length in the case of an LT glide.

6:26

Or may have a shorter taper length.

6:29

So when we think about guidewires, some of them

6:31

are floppy and hydrophilic, as we talked about.

6:34

Others may have sort of a little

6:35

atraumatic sort of curve, sort of

6:36

tip, in the case of a Rosen wire.

6:38

Nice intermediate stiffness, hydrophobic.

6:41

And some of them are like an implant,

6:42

which can be stiff and hydrophobic.

6:44

Nice, good, solid support wires.

6:46

So what are guidewire cores made of?

6:48

For the most part, stainless steel is,

6:50

you know, if you had to pick something,

6:52

stainless steel is a pretty good pick.

6:54

It has nice, good support, but it

6:56

can actually kink pretty easily.

6:58

And then, there's nitinol.

7:00

Thanks to the Navy, nickel titanium alloy

7:02

was created, nice memory alloy, no kink, but

7:07

can buckle subcutaneously without support.

7:10

So when you consider these qualities when

7:12

choosing a wire, you know, you can come up with

7:15

different wires that really fit your task at hand.

7:18

Straight, angled, stiffness, flexibility, coating,

7:23

hydrophobic, hydrophilic, and the torque ability

7:26

or opacification, the opacity of the wire.

7:29

If wires are too slippery, you know, you may

7:32

want to use a torque device to control that wire.

7:34

So, you know, wires versus

7:36

catheters versus needles.

7:37

You know, as we talked about, inches for wires,

7:40

French for catheters, and gauges for needles.

7:45

What is this?

7:47

That's our micropuncture kit.

7:48

So, 0.01 inch wire, 21 gauge needle.

7:49

190 00:07:53,040 --> 00:07:55,810 This is our transitional dilator combination.

7:56

And what that includes is our inner,

7:58

3 French, and our outer, 4 or 5 French.

8:01

Often, the inner can be stiff, in the

8:03

case of the previous slide, or it could

8:06

be. So let's look at this little guy.

8:10

Let's take this in.

8:11

So sheaths are what?

8:13

As we mentioned, that's kind of our

8:14

portal for entry into the blood vessel.

8:17

We get access, we get situated,

8:19

we put our sheath there, and like

8:20

literally, it's like a parking spot.

8:22

You know, we can do anything

8:23

from this little spot.

8:25

You know, in and out,

8:26

exchanging catheters and wires.

8:28

Because we got access.

8:29

We've achieved access.

8:30

We're here.

8:31

We've docked.

8:32

You know, as a spaceship, in

8:33

spaceship speak, we've essentially

8:35

docked in the blood vessel.

8:37

Okay?

8:37

We're here to do work.

8:39

And so typically these sheaths just allow us a

8:42

steady access point for wires and catheters.

8:45

They often have a one-way valve,

8:46

right, that prevents back bleeding.

8:49

And as I mentioned, they're measured

8:50

in essentially French, right, in this

8:53

case being a five French vascular sheath.

8:55

So it can receive a five French catheter.