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Shockwave Intravascular Lithotripsy Treatment Algorithm & Technical Success
Delaney Aguilar • Updated Apr 10, 2022 • 482 hits
Shockwave lithotripsy started in the urologic world and has recently made its way into the intravascular world. Shockwave intravascular lithotripsy (IVL) is a catheter-based therapy that delivers a wave of energy to an atheresclerotic vessel with the goal of breaking up calcified plaque. On imaging, use of Shockwave lithotripsy shows cracks within the treated plaque, making the vessel more amenable to angioplasty and decreasing the likelihood of intimal dissection.
Vascular surgeon Dr. Bryan Fisher shares his experiences using Shockwave intravascular lithotripsy to treat lower extremity arterial disease on the BackTable Podcast. Dr. Fisher discusses his treatment algorithm, the unique role of Shockwave lithotripsy, and visualizing technical success following the therapy. We’ve provided the highlight reel in this article, and you can listen to the full podcast below.
The BackTable Brief
• Shockwave lithotripsy is a purpose-built system that is prone to overuse. Dr. Fisher prefers to utilize Shockwave lithotripsy only after two separate attempts at balloon angioplasty have failed.
• Whenever a balloon touches the vessel, there is always going to be some damage caused to the intima. According to Dr. Fisher, gentle insufflation combined with Shockwave lithotripsy can decrease the risk of flow-limiting intimal dissections.
• Technical success of Shockwave lithotripsy can be observed on intravascular ultrasound (IVUS) and with optical coherence tomography (OCT), both of which can reveal cracking in calcified plaque.
Image provided by Dr. Sabeen Dhand.
Table of Contents
(1) When to Use Shockwave Lithotripsy
(2) Using Shockwave Lithotripsy to Lower the Risk of Dissections
(3) Visualizing Technical Success of Shockwave Lithotripsy
When to Use Shockwave Lithotripsy
Knowing when to incorporate shockwave lithotripsy into your treatment plan is an important step to avoid misuse and overuse. Here, Dr. Bryan Fisher discusses his preferred algorithm for use of Shockwave lithotripsy. First, he starts with a standard approach balloon dilatation. If he does not get adequate expansion then he will move to a shorter balloon and attempt to plasty with the shoulder of the balloon. Only after these two types of treatments have failed will he move on to Shockwave.
[Dr. Bryan Fisher]:
…whenever we balloon, we do an insufflation and we take that up to 4 to 6 atmospheres. We have to really understand that this is an important device to address a very specific problem. Our algorithm to avoid this kind of overuse is we'll do our definitive treatment for this atherectomy. What are we getting as far as a balloon dilatation? Oftentimes with 270 and 360 rings of calcium, you'll kind of get that napkin ring appearance. You won't get expansion. And even with higher atmospheric pressures or increased millimeters of mercury, you don't see that balloon expand in that particular area. My next step in the algorithm, I actually will go with a shorter balloon. I'll land the shoulder of the balloon and put it in that area.
[Dr. Sabeen Dhand]:
Shoulder, not the mid. Interesting. Okay.
[Dr. Bryan Fisher]:
Sometimes I can actually get that calcified area to crack as well. It's when I get failure in those two things that I then go to shockwave. And I've seen almost invariably that with very low pressures, 2 to 4, you can actually start to see, with the increased level of pulses, you see the balloons start to give way, you see the vessels start to give way, and you can see the real time luminal gain. And I'll tell you the first couple of times you see it, it's a sight to behold because that's an area that otherwise you wouldn't be able to dilate. But again, with this new technology, you can certainly see a difference.
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Using Shockwave Lithotripsy to Lower the Risk of Dissections
Anytime you touch a balloon to the intima, even with gentle insufflation at low atmospheric pressures, there is always some damage that occurs. One of the greatest risks of angioplasty is a flow-limiting dissection. According to Dr. Fisher, pre-treating with Shockwave lithotripsy allows the balloon to expand at lower pressures, thereby reducing the amount of damage that occurs to the vessel.
[Dr. Sabeen Dhand]:
Do you feel that IVL might be causing less dissection? And I know it's really hard to know, but that's one of the claims is that there's less dissection because of low atmospheres. Do you feel that you're seeing that, or you might still see the dissections but you've at least got the luminal gain?
[Dr. Bryan Fisher]:
I would say this. One of the most important things that we all have to keep in mind whenever we’re treating blood vessels. If you take a balloon to that blood vessel and you stretch it, by the very nature and physics of doing so you're going to cause injury to the intima.
[Dr. Sabeen Dhand]:
Yeah.
[Dr. Bryan Fisher]:
Now I would agree that if you take in a 6mm vessel, if you take a 7mm balloon and inflate it to 20 atmospheres, you may rupture the vessel. But in all likelihood, you're going to cause a pretty significant and probably flow-limiting dissection in that area. So as we get more gentle with our insufflations and we lower the amount of atmospheric pressures that we're delivering to the vessel wall, we minimize the amount of dissections that occur. However, the idea of eliminating those dissections, I have not seen it. And again, maybe with arteriography, if you don't look really closely, you don't necessarily appreciate that. But anytime you're touching that vessel wall and you're stretching that vessel wall, you're going to cause breaks in the intima. I'll say that with delivering low pressure in addition to those focal energies delivered to the vessel, it does minimize the amount of dissections. However, in all truthfulness, you may minimize them, but you're still causing dissection in those areas.
[Dr. Sabeen Dhand]:
Got it. When do you decide, and this is an important question for you because you have both sides of this. I mean, years of calcific lesion, you're doing all this, is it taking the need for a surgical open bypass? Is there less of a need? Or is there still as much of a need? This is a loaded question, but what I'm trying to get to is we're having all these endovascular techniques that are helping us be successful, for otherwise cases that would have not been.
Visualizing Technical Success of Shockwave Lithotripsy
Cracks within the plaque can be hard to visualize on IVUS following Shockwave lithotripsy, but going through the IVUS images slowly does indeed show the effects of Shockwave lithotripsy. Optical Coherence Tomography (OCT), though seldom used in common practice, also shows the technical outcome of lithotripsy.
[Dr. Sabeen Dhand]:
So what have you seen on IVUS post-shockwave? Do you see any differences? I mean, I know it's a low resolution of the media. When I see a cartoon drawing, I see a bunch of cracks in the media after a shockwave. Do you see anything equivalent to that?
[Dr. Bryan Fisher]:
You do see something in it and it can be quite subtle. But if you can think of a Cheerio where you crack it in a couple of different areas. If you really go through those IVUS images slowly, you can clearly see that there's evidence of true cracks in the calcium. And again, there are lots of claims everyone's made about calcium. And this is really the first company that I've seen that can show the proof and even better. I don't use this technology yet, and I'm looking and trying to incorporate it into my practice because of the imaging that you get. But OCT shows those cracks in the calcium brilliantly. And that's been really one of the more exciting aspects of that advanced imaging is seeing the proof in the pudding.
[Dr. Sabeen Dhand]:
Yeah, that's right. I mean, OCT. I agree too. I haven't used that in my practices. I see those cool orange colors that look like astronomy pictures or sometimes a black hole or something. Cardiologists use it very frequently and it is a nice new frontier that we can use.
Podcast Contributors
Dr. Bryan Fisher
Doctor Bryan T. Fisher Sr. is a practicing Vascular Surgeon and the Chief of Vascular Surgery at Tristar Centennial Medical Center in Nashville, TN.
Dr. Sabeen Dhand
Dr. Sabeen Dhand is a practicing interventional radiologist with PIH Health in Los Angeles.
Cite This Podcast
BackTable, LLC (Producer). (2021, December 13). Ep. 172 – Treating Above the Knee Calcium [Audio podcast]. Retrieved from https://www.backtable.com
Disclaimer: The Materials available on BackTable.com are for informational and educational purposes only and are not a substitute for the professional judgment of a healthcare professional in diagnosing and treating patients. The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.
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