A chronic total occlusion (CTO) is a peripheral artery segment that has been completely blocked, typically for three months or longer, allowing the occluded plaque to organize and, in many cases, calcify. In peripheral arterial disease, CTOs are common in the superficial femoral, popliteal, and tibial arteries, and they represent some of the more demanding lesions an interventionalist encounters. Successfully crossing a peripheral CTO is often the single hardest technical step in restoring blood flow to an affected limb.
Why Are Chronic Total Occlusions Difficult to Cross?
Unlike a simple stenosis, a CTO has no residual lumen for a guidewire to follow through the blocked segment. The occluded plaque may contain a mixture of soft thrombus, organized fibrous tissue, and calcium deposits that have built up over months, creating a dense, unpredictable barrier. Wires can inadvertently exit the true lumen and travel between the layers of the vessel wall, sometimes without immediate operator awareness, which is why CTO crossing relies heavily on fluoroscopic road-mapping, careful wire selection, and an understanding of the two broad crossing strategies available.
Intraluminal vs Subintimal Crossing: What Is the Difference?
Intraluminal crossing aims to keep the guidewire within the artery's true, original lumen throughout the occluded segment, generally regarded as the more anatomically direct approach when achievable. Subintimal crossing intentionally advances the wire into the space between the intima and adventitia (the subintimal plane), tunneling around the occlusion before attempting to reenter the true lumen distal to the blockage. Both strategies are established techniques in peripheral CTO management, and operators often start with an intraluminal attempt, converting to a subintimal approach if progress stalls.
The Role of Reentry Devices
When a subintimal path is taken, the guidewire must find its way back into the true lumen beyond the occlusion — a step that is not always straightforward, since the subintimal space can extend past the original blockage. Dedicated reentry devices and techniques have been developed to help operators redirect the wire from the subintimal plane back into the true lumen at a controlled location, reducing the risk of a large, uncontrolled dissection or the need to abandon the endovascular attempt in favor of open surgery.
How Guidewire Selection Shapes the Approach
CTO crossing typically follows an escalation strategy, starting with a lower tip-load wire and progressing to stiffer, higher tip-load wires if the softer wire cannot penetrate the proximal fibrous cap of the occlusion. Wire tip coatings, shaft support, and steerability all influence how effectively a wire can be directed through — or safely diverted around — the occluded segment. Operators frequently exchange wires multiple times during a single CTO crossing attempt as feedback from tactile resistance and fluoroscopic appearance guides the next step.
Imaging Support During CTO Crossing
Because CTO anatomy is often unpredictable, imaging plays a central role throughout the crossing attempt. Biplane or angled fluoroscopy helps visualize wire position relative to calcified plaque, while intravascular ultrasound (IVUS) can be used in select cases to confirm whether the wire tip sits in the true lumen or has strayed subintimally. This imaging feedback loop helps the operator decide in real time whether to continue, change wire, switch strategy, or abandon the endovascular attempt.
What Happens After Successful Crossing?
Once a wire crosses the CTO and true lumen position is confirmed, the vessel is typically prepared with balloon angioplasty, sometimes combined with atherectomy in heavily calcified segments, before a stent — often a self-expanding nitinol design suited to the femoropopliteal segment's mobility — is placed to maintain the newly reopened channel. INVAMED's peripheral portfolio, including the Atlas Peripheral Stent System, is among the devices used downstream of successful CTO crossing in appropriate candidates, with suitability determined by the treating physician. For a broader view of the peripheral device landscape used across the CTO workflow, see the peripheral arterial disease device category.
How long does CTO crossing typically take during a procedure?
Duration varies considerably depending on occlusion length, calcification, and how the vessel responds to initial wire attempts; some CTOs cross within minutes, while heavily calcified or long occlusions can extend procedure time substantially. The overall procedure time reported to a patient usually reflects this variability rather than a fixed duration.
Device availability and regulatory status vary by country. Please contact INVAMED or your authorized local distributor for current regulatory information applicable to your region.