Intravascular ultrasound (IVUS) is a versatile device used for both arterial and venous applications. In episode 52 of the BackTable podcast, Dr. Michael Cumming and Dr. Mark Lessne discuss indications for IVUS, false positives to watch out for, and why IVUS is a valuable tool for diagnosing central venous pathology.
The BackTable Brief
IVUS has a wide variety of venous and arterial applications; Dr. Cumming and Dr. Lessne use IVUS for PAD stenoses, in cases of iliac vein compression, and to complement venous interventions.
Avoid false positives when using IVUS by differentiating between fixed and variable stenoses; respiratory variation, uterine fibroids and catheter maneuvering around L5-S1 may cause concern for stenosis in an otherwise normal vessel.
For suspected central venous pathology (i.e left brachiocephalic compression or venous webs) IVUS may identify subtleties not seen on venography.
Disclaimer: The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.
Evaluating Arterial and Venous Disease Using IVUS
Between accurate vessel measurements, minimizing contrast, and decreased fluoroscopy times, IVUS is a powerful tool for the evaluation of venous and arterial disease. Dr. Cumming uses IVUS in the majority of his new PAD cases. Dr. Lessne uses IVUS for all venous interventions, and often combines IVUS and venography for evaluating chronic venous disease.
Mike, what all are you using IVUS for, either on the venous or arterial side?
I use IVUS pretty much routinely. In the majority of my PAD new cases I'll use IVUS. Obviously for iliac vein compression, pelvic venous congestion … those are great cases for IVUS. I hate not using IVUS. I think it gives us great delineation, it gives us very accurate measurements, and it saves on fluoro time.
Okay. Mark, what about you?
Yeah, so I'll use IVUS for all my venous interventions, especially chronic venous interventions within the acute setting. If I'm not doing single session, I’ll usually defer IVUS until I'm done and ready to finish up the job. But I'll tell you, Mike made some really important points that I want to make sure we don't gloss over them. He talks about how we use IVUS and how we think about that in terms of looking for 50% narrowing in iliac veins, and we're looking for cross sectional area. And all of these things are somewhat arbitrarily defined by our gut, and our expertise for whatever that means. There's a big trial, the VIDIO trial, which showed that IVUS changes clinical management in a good percentage of patients.
The problem is, and this is the point that Mike made that can't be understated, we never show that it changes clinical management for the better. So there's no study that shows, "Oh, when I use IVUS, the Villalta score decreases, quality of life increases." All we know is that when I use IVUS, I angioplasty it and stent it whereas before I wouldn't have, but we really don't know. So I think getting familiar with IVUS is important, but I think we have to know its limitations. So you asked me where I use it, I use it as a complementary tool in almost all my chronic venous cases, but along with flow dynamics of venography.
What false positives are commonly seen with IVUS?
IVUS false positives may arise in patients with uterine fibroids, during respiratory variation, and with catheter manipulation at the L5-S1 level. Dr. Lessne has observed false positives when large fibroids cause venous impingement, and always looks for a fixed stenosis to rule out respiratory variation. Dr. Cumming has noticed the IVUS catheter may become biased against the vessel wall at the L5-S1 region, which may cause a stenotic appearance.
… Mark, I think it'd be interesting to talk a little more about IVUS, its false positives, how to avoid false positives and what your experience has been with them.
Yeah, I think that's a great question. I think it's a difficult topic. So I think the important thing for our listeners is to know, I suspect Mike feels the same way, no one gets on our table for even an evaluation unless their clinical symptoms warrant it. In other words, just because we see reflux, just because we see something on CT scan, that is almost irrelevant. The only thing that matters is that a patient has a clinical presentation that may be compatible with non thrombotic iliac vein compression syndrome. And so once again on the table, the IVUS is to confirm that.
Now in terms of false positives, I've seen false positives in patients with fibroids. That can be specifically difficult because obviously a lot of women come in with pelvic pain, pelvic pressure, maybe some varicosities. But is the vein just compressing from their fibroids? In which case maybe fibroid embolization or myomectomy may be performed. Same thing with respiratory variation. I've seen some very dramatic examples where you have almost near complete obliteration of the vein and then a patient breathes deeply and it's wide open. So a fixed stenosis is really what I'm looking for.
Agree Mark. I have a hard time with that non-fixed lesion and really believing that it's hemodynamically significant. But I think that speaks a lot to your intent to treat, and your desire to treat and you could make IVUS look positive and just about any patient. If you have them take a big breath in and the vein disappears. The other sort of technical limitation is when the vein drapes around L5 and S1, the catheter is biased against one wall of the vein and you can't see through the bone. Often you'll miss a lot of normal vein - you could draw your area measurements wherever you want and create a stenosis that really isn't there.
Should IVUS be used for central venous cases?
Dr. Lessne uses IVUS for central venous cases in which there is questionable concern despite having a normal venogram; IVUS may reveal venous webs when venography is negative. IVUS may also help in the diagnosis of left brachiocephalic compression.
Mark, are you using IVUS for your central venous cases as well?
Yeah, it's a good question. So I would say I have a very large thoracic venous obstructive practice and I will use it for areas of questionable concern. So in other words, a patient comes with arm swelling and they've gotten nothing on venography, I've used it for them to identify webs that can be subtle. The other thing is there is a compressive syndrome in the chest called left brachiocephalic or innominate compression. It’s where the vein gets compressed between the sternum and the aorta and IVUS can be helpful there. So I will use it then. It's certainly not performed as routinely as in the lower extremity and pelvis. But you can use it for problem solving in the thoracic veins as well.
Dr. Mark Lessne is a practicing interventional radiologist with Charlotte Radiology in North Carolina.
Dr. Michael Cumming is a practicing interventional radiologist in Minneapolis, MN.
Dr. Michael Barraza is a practicing interventional radiologist with Radiology Alliance in Nashville, Tennessee.
Cite this podcast:
BackTable, LLC (Producer). (2019, November 11). Ep 52 – IVUS for Iliac Vein Compression [Audio podcast]. Retrieved from http://www.backtable.com/podcasts
The Materials available on the BackTable Blog 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.
This episode was sponsored by RADPAD radiation protection.