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Chronic Total Occlusion (CTO) Basics

Author Caleb Solivio covers Chronic Total Occlusion (CTO) Basics on BackTable VI

Caleb Solivio • Aug 13, 2023 • 105 hits

This article examines the technical aspects of managing chronic total occlusions (CTOs), a common yet complex task for the peripheral interventionalist. It discusses the need for versatile strategies to variable CTO morphologies, and outlines the role of CTOP classification in shaping these strategies. The text further explains the use of specific devices, such as the Outback and Pioneer, and emphasizes the importance of accurate measurements and correct re-entry points to minimize potential complications.

This article features transcripts for the BackTable Podcast. We’ve provided the highlight reel here, and you can listen to the full podcast below.

The Backtable Brief

• CTOs are a common pathology in patients with PAD that can be alleviated by endovascular therapies in order to restore blood flow to distal parts of the lower extremities; effectively saving patients’ limbs from amputations.

• One of the most important factors in determining technical success in crossing CTOs is the CTOP (chronic total occlusion (CTO) crossing approach based on plaque cap morphology) classification system.

• CTOP grades CTO plaque caps in order from least complex (I, two concave caps) to most complex (IV, two convex caps).

• Though an operator’s preferred technique and experience is important in crossing CTOs, it is important to think about back up options, such as the use of re-entry devices, to successfully treat PAD patients that present with CTOs.

Chronic Total Occlusion (CTO) Basics

Table of Contents

(1) Basic Chronic Total Occlusion (CTO) Techniques

(2) The Importance of CTOP Classification

Basic Chronic Total Occlusion (CTO) Techniques

Interventional radiologists face numerous challenges when managing chronic total occlusions (CTOs), regardless of their length or classification. Key to effective management of CTOs is technical adaptability to their inherent unpredictability. Devices like Outback and Pioneer have proven to be crucial aids, particularly when re-entry in the superficial femoral artery (SFA) or popliteal becomes necessary. Still, each technique carries its own potential pitfalls. Because the management of CTOs can be so tricky, lending themselves to detrimental consequences such as entering subintimal planes or, worse, perforation, accurate measurement and identification of proper re-entry points are crucial to avoid potential complications.

[Dr. Sabeen Dhand]
Now, my question for you just, to begin with, is what are some basic techniques that we can just list and talk about that you use when you see a long chronic total occlusion? What are some things that any operator should be comfortable with?

[Dr. Jihad Mustapha]
CTOs are never friendly. Long, short, classified, and unclassified. As long as you accept that right off the bat and knowing that you're going into a CTO and expect the unexpected, you're going to do well. The basics of chronic total occlusions is approaching it from the best directions for instance. Up and over in the United States still actually the primary methods.

We do initial angiography up and over, take a look at the CTO, and then we do the wire catheter technique and try to cross with that and then, quite frankly, we try for maybe five minutes. If you don't make headways in five minutes, we tend to shift to alternative methods. If we make headways and we cross the CTO, but we can't re-enter distally, then we have multiple methods.

Outbacks, Pioneers are really great devices, and I had the luxury of working with them for actually a long time and got to study them very well. They do help in situations where you have to re-enter in SFA or popliteal. It becomes more problematic when you go to P3 or the popliteal. If you can re-enter without them, it's great but if you have to re-enter with them, we can discuss the pitfalls the good, and the bad, tips and tricks.

Finally, one thing that I'd like to caution everyone of, CTOs are tricky. If you have a CTO that you measure and it's 150 millimeters, you should re-enter at 151 or 152 or something like this.

[Dr. Sabeen Dhand]
Not like 6 to 7 centimeters past the reconstituted segment.

[Dr. Jihad Mustapha]
Yes. If you can't do that, then you have to find another way. We can talk about that as we go.

[Dr. Sabeen Dhand]
We briefly touched on that. There's nothing like when you get really, I'm going to quote, "lucky." I think it's lucky when you loop that wire. You get there, you're right next to where the reconstituted segment is, and then you straighten out the wire, and boom, it goes luminal. You're just like, "Okay." You might drop and you're pretty much done with the case after a lot more steps.

Listen to the Full Podcast

Tools for Crossing Challenging CTOs with Dr. Jihad Mustapha on the BackTable VI Podcast)
Ep 305 Tools for Crossing Challenging CTOs with Dr. Jihad Mustapha
00:00 / 01:04

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The Importance of CTOP Classification

CTOP classification plays a pivotal role in navigating chronic total occlusions (CTOs), serving as a guide to selecting the most effective and safest techniques for each patient. Its utility lies in the understanding of CTO cap morphology, facilitating critical decisions when conventional approaches, such as the wire catheter technique, meet obstacles. For instance, a Type III CTOP, characterized by an antegrade convex cap and distal concavity, often leads to wire deflection at the proximal portion, signaling a need to reevaluate the chosen strategy. The inherent challenges presented by the unique morphology of each occlusion necessitate a thoughtful approach that respects the anatomy while minimizing potential harm, such as dissection or perforation.

[Dr. Sabeen Dhand]
We've all been there when you're doing these CTOs where you're trying the conventional technique, the wire is looped, and now all of a sudden, the loop is extending. When I'm saying loop, it's in the subintimal plane and it's extending past that point. That's where you start saying, "Okay, exactly." You want to come back where it's reconstituted. You have talked about CTOP plenty of times before. Is CTOP still something that you are-- the classification, is it something that you use on every single case?

[Dr. Jihad Mustapha]
Absolutely, Sabeen. If you really want to be doing the safest thing for the patient, which all of us do. We'll probably all do it subconsciously without knowing, even if we know the CTOP classification or we don't, every one of us probably think the same way. What is the safest way to reconstruct the CTO? If you have a type III CTOP which you have an antegrade convex cap, and retrograde-- sorry, distally will be concave.

It's going to be difficult to come from above and the wire get deflected left and right at the proximal portion. When you see the wire coming down and suddenly hitting something and goes left or right, you know you have a problem there. This is where you have to decide, should I stick with the wire catheter technique here because I'm going to go subintimal for sure, or do something else?

This is where the CTOP really helps. Then the other option would be if you have a nice convex CTO cap where the wire catheter will go right through it and when you get distally and the wire get deflected again, right or left, that's where you have to stop and think, how much do I want to mess with this vessel down here? Do I want to perforate it, dissect it, or should I go into alternative methods as well?

Alternative method would be using Outback and Pioneer, that's two methods that are known to be good and effective. I remember the shaft of the Outback, some of the shafts are 80 centimeters, some are a little longer. You have to be careful which one you pick if you pick it. That's an advice I would like to give everybody. Make sure you check the shaft.

Podcast Contributors

Dr. Jihad Mustapha discusses Tools for Crossing Challenging CTOs on the BackTable 305 Podcast

Dr. Jihad Mustapha

Dr. Jihad Mustapha is a practicing Interventional Cardiologist and CEO at Advanced Cardiac & Vascular Centers for Amputation Prevention in Michigan.

Dr. Sabeen Dhand discusses Tools for Crossing Challenging CTOs on the BackTable 305 Podcast

Dr. Sabeen Dhand

Dr. Sabeen Dhand is a practicing interventional radiologist with PIH Health in Los Angeles.

Cite This Podcast

BackTable, LLC (Producer). (2023, March 27). Ep. 305 – Tools for Crossing Challenging CTOs [Audio podcast]. Retrieved from

Disclaimer: The Materials available on 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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