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Liquid Vs. Glass: The Secret To A Flexible Laser Catheter

Q&A With Co-Founder/CEO Of Ra Medical Systems

Kym: What sparked your interest in innovating with lasers?
Dean: Well, it really started at General Atomics back in the very early 1980s when I was working on maser systems. Now, a maser is very similar to a laser, only instead of putting out light, it puts out microwaves.
Kym: Okay. And what do you do with that?
Dean: Well, at the time it was used for heating plasmas for thermonuclear fusion, and I took my knowledge of electronics and how that kind of power system work and began to apply it to the excimer laser.
Kym: Gotcha. And...
Dean: So in the early 1990s, I started working on my first excimer laser with a very small group, and that was actually to clear out blockages in arteries.
Kym: Oh, really?
Dean: Yes. So that was in 1991, and we were working on a very simple system that turned out to be quite complicated, not just from a system standpoint, but from a material standpoint. We had a lot of trouble getting the laser energy to where it's needed inside the vasculature, to the blockage in the artery.
Kym: Oh, gotcha. So what happened?
Dean: Well, we were using a solid piece of glass, and that was our only real solution to the problem back then.
Kym: Explain the purpose for the glass.
Dean: Well, the glass transmits… It's like a fiber optic, and it transmits the laser energy from the laser, which is a fairly large box, inside the body to the blockage within the artery. Our problem was is the glass was just too stiff.
Kym: Gotcha.
Dean: If we made it too small, it wouldn't deliver enough energy or remove enough material, and if we made it too large, we couldn't navigate the vasculature. That is, it wouldn't handle the tortuosity of our anatomy.

Kym: Spectranetics was able to create a glass fiber bundle that was more flexible than a solid piece of glass. But it had a lot of dead space in the delivery mechanism, so patients weren't being treated with 100% laser light. Plus, the box encasing their energy source, doctors say is too large, and sometimes the device has burned patients because it forms a hot vapor bubble in the saline to make up for the dead space. Doctors love it for leed extraction, though. It left room, however, for innovation in atherectomy. That's where you saw the opportunity. How did you create a full-fill delivery mechanism?

Dean: So instead of using glass, we decided to use a liquid to get the energy from the laser to the blockage.
Kym: What was the "aha" moment for you where you said, "Wait a minute. Let's not use glass. Let's go to the liquid"?
Dean: Well, as you know, the excimer laser breaks down molecular bonds. Well, it wants to break down molecular bonds in just about everything. That's the problem. So there are very few materials that will transmit this energy. So as it turns out, water and slight variations of water is a great transmitter of this light. So what we needed to do was package that up into something that was similar to a fiber optic but not made of glass but made of water, and we've been able to do that.
Kym: Now, paint the picture for us, just so people kind of understand how this works, and you were telling me about the Las Vegas fountains. So use that analogy.
Dean: Yes. So effectively our catheter is a plastic tube, a fairly small plastic tube that has little windows on each end to hold the liquid in, and inside is a very small column of liquid. That liquid transmits the light just like a fiber optic would or just like the Bellagio fountains would contain the light for their show.

Kym: And having 100% laser light, creates a non-thermal ablation tool for unclogging arteries, I would assume, completely vaporizing the the plaque or whatever is creating a blockage, leaving a clean channel with no debris?

Dean: Yes. The excimer laser can ablate right through the rock hard calcium and other buildup in the arteries, and it literally turns the material back into its constituent components comprised of proteins, lipids, minerals, and water, materials that are already a part of the bloodstream. It works in the same was as the excimer laser used for LASIK eye surgery.

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