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Page 2 of 11 Zivelonghi et al. Vessel Plus 2019;3:30 I http://dx.doi.org/10.20517/2574-1209.2019.06

Figure 1. Flowchart showing the possible dissection/re-entry techniques. CART: controlled antegrade and retrograde subintimal tracking;
LAST: limited antegrade subintimal tracking; STAR: subintimal track and reentry

be performed both via retrograde or antegrade approaches [Figure 1]. One of the first techniques was
[1]
introduced by Colombo et al. namely the subintimal track and reentry (STAR) technique (this technique
was first developed for peripheral interventions). To obtain the “dissection and re-entry” Colombo
used a polymer jacket looped guidewire (“knuckle wire”) such as the Fielder-XT or the Pilot 200, that
entered easily in the sub-intimal space before the occlusion (because of its hydrophilic properties) and
could manage to spontaneously re-enter in the true lumen when approaching a bifurcation in a more
distal segment of the vessel. Since its first description in 2005, this technique has experienced many
[2]
evolutions according to different operators. In 2008, Carlino et al. reported for the first time its sub-
intimal technique, performed by placing a microcatheter in the subintimal space, and injecting contrast
to visualize the subintimal course and thus facilitating driving of the guidewire. This technique is known
as contrast-guided STAR technique. In addition, the limited antegrade subintimal tracking (LAST)
[3]
technique has been introduced by Lombardi in 2009: this consists in the progression of a guidewire in
the subintimal space, performing a re-entry as proximal as possible after the occlusion. The guidewire
must be previously knuckled to create a loop with a very acute angle, to facilitate the re-entry. With the
introduction of the CrossBoss and the Stingray Catheters (Boston Scientific) since 2012 the success rate of
the CTO dissection re-entry procedure has been improved. In the mini-STAR technique introduced by
[4]
Galassi et al. since 2012 a microcatheter (generally the Finecross, Terumo, Tokyo Japan) is advanced up to
the proximal cap of the CTO using a spring soft guidewire that must be exchanged with a Fielder wire that
addressed the true lumen.

Focusing now on retrograde approach, the retrograde dissection can be obtained with a knuckle guidewire,
the re-entry can be achieved with two different techniques. The first one is the controlled antegrade and
[5]
retrograde subintimal tracking (CART) technique, introduced by Surmely et al. in 2006. As a first step,
the operator should place the retrograde guidewire into the subintimal space. A balloon is advanced
through the retrograde guidewire and inflated in the subintimal space in order to track the advancing of
the antegrade guidewire into the distal vessel. The second (and currently most common) is the reverse
CART technique, which is conceptually similar to the previous technique but inverted. The balloon is