Antegrade dissection and re-entry for chronic total occlusions
Antegrade dissection and re-entry for chronic total occlusions: Opening up of chronic total occlusions (generally more than 3 months old) is always challenging. While attempting to wire a chronic total occlusion (CTO), the wire can go subintimally and then renter the true lumen distally. Unless there is guidance with intravascular ultrasound (IVUS) or optical coherence tomography (OCT), it is almost a blind try.
In the technique known as sub-intimal tracking and re-entry (STAR) technique, a knuckled wire was passed . But this produced an uncontrolled re-entry, sometimes very distally near a bifurcation. Stenting then would result in run off into one terminal branch. Hence long term results were not good . There were other techniques like limited antegrade sub-intimal tracking (LAST), which also had significant limitations .
Because of the unreliability of conventional antegrade dissection and re-entry (ADR) techniques, special hardware have been developed, to improve results. They are the CrossBoss and Stingray system (Boston Scientific, Marlborough, MA, USA) . CrossBoss catheter has a 1 mm rounded tip which can be used as a blunt dissection tool. In 10% of cases, it can track through the intimal plaque and re-enter the distal true lumen. It can also be used to produce a controlled dissection in the sub intimal space so that the Stingray balloon can be delivered just beyond the distal cap of the CTO. These devices thus allow a focused puncture so that all distal branches get adquate blood flow. This technique has redproducibility and predictability of the re-entry site, unlike the older techniques. But the hardware is more expensive.
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