1. G. Capretti, M. Carlino, A. Colombo, L. Azzalini
Rotational atherectomy in the subadventitial space to allow chronic total occlusion recanalization: pushing the limit further
G. Capretti, M. Carlino, A. Colombo, L. Azzalini
San Raffaele Hospital
Milan, Italy

2. Giuliana Capretti and Lorenzo Azzalini
We have no relevant financial relationships

3. Learning objectives
Troubleshooting algorithm of uncrossable lesion during chronic total occlusion (CTO) PCI
How to perform rotational atherectomy in the subadventitial space in CTO PCI
Possible complications and how to avoid/treat them

4. Clinical Presentation
60-year-old male
History of hypertension, hyperlipidemia, chronic obstructive pulmonary disease, coronary artery disease (mid LAD 70%, mid RCA CTO) and severe peripheral artery disease
Recent PCI with 2 DES on the LAD
Residual inferior-wall ischemia (myocardial perfusion imaging)
Admitted for RCA CTO PCI

5. Angiography
(A) RCA CTO. The occlusion is long, with an ambiguous proximal cap, and good interventional septal collaterals (B) from the LAD.
According to the hybrid algorithm, a retrograde approach is chosen.

6. Angiography
(C) After septal surfing, the distal RCA is reached and the subadventitial space is accessed with a knuckled Pilot Corsair, which however cannot overcome a spot of focal resistance in the mid RCA. The knuckle is further strengthened using (D) the radiotransparent (stiffer) part of the guidewire (arrow).

7. Angiography
The knuckle is further strengthened also using (E) the Corsair tip itself, to no avail. A microinjection of contrast is performed through the Corsair (modified Carlino technique, arrow), but neither guidewires nor the Corsair can cross the focal spot of resistance.

8. Angiography
(A) Rotational atherectomy is performed onto the antegrade wire, although this is located into subadventitial space and its tip cannot reach the distal true lumen. (B) The retrograde Corsair+Pilot 200 are then successfully advanced beyond the focal area of resistance and reverse CART is performed. After retrograde wire entry into the antregrade guiding (tip-in technique), PCI is then carried out as per standard practice.

9. Angiography
Final result after implantation of 4 DES (from the PDA to the RCA ostium). The PL is recanalized with STAR (final TIMI 2). Optimal angiographic result on RCA-PDA.

10. Learning objective 1
Troubleshooting algorithm of uncrossable lesion during chronic total occlusion (CTO) PCI:
Increase support (e.g., mother-and-child)  impossible (retrograde approach)
Power-knuckle (with stiff part of guidewire)
Modified Carlino technique
Laser  very high risk of perforation (dissection plane)
Tornus  lack of support (diseased proximal RCA)
External crush
Rotational atherectomy (RA)
Attempted, but failed
Attempted, succeeded

11. Learning objective 2
How to perform rotational atherectomy in the subadventitial space in CTO PCI:
Small burr (1.25 mm)
Pecking motion
Conventional speeds (160, ,000 rpm)
Wire does not need to be in the distal true lumen, although it is mandatory to confirm that its situation is within the vessel architecture throughout the occlusion

12. Learning objective 3
Possible complications and how to avoid/treat them:
Perforation  confirm wire position in vessel architecture; be familiar with coils, covered stents, pericardiocentesis, ping-pong technique, etc.
AV block, slow-flow  do not happen in CTO PCI (vessel is already occluded)
Burr entrapment  extremely rare in the subadventitial space (burr moves along low-resistance cleavage plane); parallel wiring in subadventitial space + ballooning, mother-and-child catheter, etc.

13. Take Home Messages
The subadventitial space is an environment where devices can be safely manipulated within the limit of the resistant adventitia
Rotational atherectomy (RA) performed in dissection planes is safe, as long as wire position in the vessel architecture is confirmed
Perforation specifically linked to RA in this setting is expected to be extremely improbable (if proper technique is used)
Specific equipment and skills must be available in the cath lab when any RA procedure is performed