Complex CTOs

CTO REVASCULARIZATION series – Part 2C

Once the decision is made to go subintimal, the technique becomes a matter of discipline: keeping the loop small, advancing the catheter behind the wire, and re-entering the true lumen right at the distal cap - the most demanding step of the entire procedure.

The two halves of subintimal recanalization: entering the plane and keeping the loop small at the proximal cap (left), and re-entering the true lumen right at the distal cap (right).

The Subintimal Plane and the Re-entry Problem

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In the previous two articles (read the first here and the second here) we discussed the strategic dimension of long and multilevel CTOs and the relationship between intraluminal and subintimal recanalization. We turn now to the operational technique: how to handle the subintimal plane, and how to manage the most demanding phase of the entire procedure, the re-entry into the true lumen.

Entering and maintaining the subintimal plane

When sliding and drilling fail and the decision is made to go subintimal, the maneuver is straightforward: the catheter is oriented toward the vessel wall – adjacent to the proximal cap – and a low-to-moderate tip-load guidewire (V18 by Boston Scientific or equivalent in the femoropopliteal segment) is gently advanced. The wire creates a dissection between the intima and the media, entering the subintimal space. The unmistakable sign of correct entry is the characteristic loop the wire tip forms.

Schematic of a femoropopliteal CTO with a guidewire entering the subintimal plane at the proximal cap, with magnified inset showing the loop at the wire tip. — Figure 1 - Entry into the subintimal plane at the proximal cap. The characteristic loop at the wire tip is the sign of correct entry: keep it small.

Side-by-side schematic of two crossing strategies for a long femoropopliteal CTO: subintimal (left), guidewire looping between plaque and wall; intraluminal (right), wire through the plaque.

CTO REVASCULARIZATION Series — Part 2B

Once the Target Arterial Path is chosen, the technical question becomes how to cross the CTO. In long femoropopliteal occlusions the relationship between intraluminal and subintimal recanalization is more nuanced than the textbook sequence suggests — three scenarios worth distinguishing.

Schematic representation of a long femoropopliteal chronic total occlusion exceeding 15-25 cm, the morphological hallmark of TASC II D and GLASS FP grade 4 lesions

CTO REVASCULARIZATION Series: Part 2A

Before discussing how to cross a long or multilevel CTO, we need a more fundamental question: which vessel do we recanalize? The strategic framework of the 2019 Global Vascular Guidelines — Target Arterial Path, GLASS, and the role of the angiosome — defines everything that follows.

CTO REVASCULARIZATION

Heavy calcification is not just a technical obstacle — it changes the rules of the game entirely. In this issue: why the subintimal approach often fails in the highly calcified pattern, and why staying endoluminal is both the harder and the smarter choice

What Does Infrainguinal “Complex Recanalization” Really Mean?

We use the term all the time. But complex recanalization is not an anatomical category — it’s a decision point. Here’s the operational definition that changes how you plan your next CTO case.

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CTO REVASCULARIZATION Series — Part 2B

CTO REVASCULARIZATION Series: Part 2A

CTO REVASCULARIZATION

What Does Infrainguinal “Complex Recanalization” Really Mean?