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Colombo et al. Vessel Plus 2019;3:29 I http://dx.doi.org/10.20517/2574-1209.2019.005 Page 7 of 9

to be considered in all patients undergoing CTO interventions. Many prophylactic measures have been
proposed to avoid kidney damage, however hydration with saline solution administration (1 mL/kg for 6 h
before and 12 h after the procedure) has been proven to have the best outcomes.

During CTO PCI, repeated contrast injection should be avoided. Retrograde approach usually requires less
contrast, likely due to use of “tip-injection”. Similarly to non-CTO PCI, IVUS employment can contribute
to reduce contrast amount in several ways (IVUS-guided antegrade puncture, vessel diameter and disease
extension evaluation).

VASCULAR ACCESS COMPLICATIONS
CTO PCI usually requires dual arterial access and larger sheath diameter, compared to non-CTO PCI.
[17]
Both conditions increase the probability of vascular access complications with reported rate of 0.5%-1.5% .
Compared with femoral access, radial approach is associated with lower adverse cardiac events and
[18]
major vascular complications rates across the entire spectrum of patients with stable or unstable CAD .
TM
Moreover, the development of thin-walled sheaths (e.g., 7 in 6 French Glidesheath Slender , Terumo)
and sheathless techniques made feasible complex PCIs requiring 7 French catheters also from the radial
access. Indeed, even in CTO PCI, a fully transradial approach has been proven to be safe with a high rate
[19]
of success and low complications incidence . On the other hand, due to technical aspects (e.g., multiple
devices housing in the same catheter), 8 French catheters may be needed and in these cases femoral access
is the most practical way. Furthermore, depending on anatomical characteristics, when strong back up
support is desirable, 45 cm long femoral sheaths could provide it. For all these reasons vascular access
choice is left to the operator’s discretion.

RADIATION SKIN INJURY
Radiation skin injury is of particular concern in patients undergoing CTO PCI, as long fluoroscopy
and cine-angiography exposure may be required to cross and treat the lesion. However radiation injury
[5]
incidence is low (< 0.01%) , but the data are under-reported in literature. Tricks to minimize radiation
exposure are reducing frame rate of fluoroscopy and cine; another ploy is the use of stored fluoroscopy
instead of angiography. Newer angiographic devices with low-dose settings could also reduce patient
radiation exposure.

CONCLUSION
CTOs represent the most technically challenging lesions that interventional cardiologists face in everyday
practice. However, due to newer dedicated devices and improved techniques, the rate of successful CTOs
recanalization is increasing whereas the rate of complications is reducing. Nevertheless peri-procedural
complications incidence, particularly in retrograde approach, is still higher than in non-CTO PCI.
Operators approaching to CTO PCI should also be aware of the unique set of complications associated
with CTOs recanalization. Consciousness of the potential specific CTO PCI complications is the first step
to prevent and solve them. Then the knowledge of techniques and equipment available for complications
management, combined with operators’ experience, will contribute to safe percutaneous treatment of
CTOs.

DECLARATIONS
Authors’ contributions
Searched for literature data and wrote the paper: Colombo F, Bernardi A
Conceived the structure of the chapter and reviewed the manuscript: Garbo R