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Page 6 of 11 Zivelonghi et al. Vessel Plus 2019;3:30 I http://dx.doi.org/10.20517/2574-1209.2019.06

4. Small outer diameter over the wire (OWT) microcatheters like Finecross (Terumo-corporation), Quick
Cross (Spectranetics corporation, Colorado) or Supercross (Teleflex) for wire support and exchange. Also
of these catheters an antegrade and a retrograde version exists.

5. Small OWT balloons for support and exchange are in general not recommended in contemporary CTO
PCI.

6. Tornus microcatheter (Asahi, Intecc): Tornus has a solid metal body, while the outer surface is
hydrophobic coated. It is a penetration microcatheter that allows to expand the lumen of calcified vessels,
providing easy access to other medical devices and improving the treatment of tight lesions. It allows to
cross CTO through helical movements.

7. CrossBoss microcatheter (Boston Scientific): this is a metal OTW microcatheter with a rounded “olive-
shaped” tip. Once inserted in the body of the CTO lesion, it is rotated rapidly in either direction to facilitate
advancement through a CTO without the wire in the lead. It is a key device for controlled antegrade sub-
[13]
intimal dissection/re-entry techniques . It creates a controlled blunt dissection of the segment tracked.
Due to its shape, the chance to perforate is limited. The device tends to maintain a subintimal position
during advancement. It is used only during antegrade procedures.

8. Stingray balloon and Stingray guidewire systems (Boston Scientific): it is a 1-mm flat dual-parallel
[13]
balloon with 3 exits ports connected to the same guidewire lumen . It is a device for reentry purposes
distal to the CTO segment (thus to be used only in antegrade procedures). The distal exit port is used to
place the balloon in position. When the balloon is inflated it generates a flat surface (due to the 2 parallel
balloons) that accommodates itself in the subintimal space around the intima. Once inflated, the other two
exit ports, which are both just before the distal one, are 180° opposed, so one is oriented to the adventitia
[6]
and the other to the lumen. It is used for true lumen re-entry .
To manage complications like coronary perforation and cardiac tamponade the Cath lab must be equipped
with covered stents, embolization coils, pericardiocentesis kit and the operators should be trained for the
treatment of these dangerous complications.

TECHNIQUES
Access
[14]
The operator should use access routes which he/she is more familiar with . On one hand the femoral
access allows the use of larger guiding catheters improving the support, on the other hand the radial
approach improves patient comfort and reduces complications . Both are acceptable. In the sub-analysis
[15]
from the RECHARGE trial, the use of a fTRA resulted feasible in the whole spectrum of difficulties
for CTO revascularization . In these cases, more supportive guiding catheters are preferred to allow
[11]
enough penetrative power and overcome the most resilient proximal cap. Guiding catheter size is usually
limited to 6-7 French (occasionally 7F) from the radial approach, compared with standard 8 French used
[16]
in transfemoral CTO PCI . All the operators but especially radial operators, should be familiar with
all the techniques that can improve the support like balloon anchoring, mother and child techniques
[17]
and guiding extension devices . The balloon anchoring is achieved by inflating a balloon into a small
branch of the target vessel proximal to the CTO segment to obtain support to overcome the lesion. The
mother and child technique provides to insert a smaller French catheter into a larger catheter to improve
support to the guidewire. Nowadays guiding catheter extension devices such as Guideliner (Teleflex) and
Guidezilla (Boston Scientific) are available and better choice than mother and child guiding catheters. It
is recommended to start the procedure with ipsilateral and contralateral injection for a proper diagnostic