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Page 6 of 22 Andò et al. Vessel Plus 2023;7:15 https://dx.doi.org/10.20517/2574-1209.2023.26

The position of the imaging catheter (IVUS or OCT) with respect to an eccentric calcified plaque may also
help in predicting the impact of the rotational atherectomy burr on the plaque. For example, if the imaging
catheter is in contact with the wall opposite to that in which the greater calcific component is present, with a
larger caliber burr than initially foreseen, it will be possible to obtain greater contact between the device
itself and the calcific plaque, and therefore greater efficacy in calcium ablation . Finally, intravascular
[36]
imaging plays a fundamental role in the evaluation of the result of stenting and OCT has a much greater
sensitivity than IVUS in detecting stent malapposition or under-expansion and in appreciating the effects of
post-dilatation [35,37,38] .

TECHNICAL CONSIDERATIONS FOR PERCUTANEOUS CORONARY INTERVENTION (PCI)
OF HEAVILY CALCIFIC CORONARY LESIONS
Vascular access, guiding catheters, and guidewires
PCI of heavily calcified lesions requires careful planning. Femoral access may be considered in situations
which may require a lumen guide catheter greater than 6 French (F, 1F = 0.3 mm), especially in the presence
of small-caliber radial arteries or in case of extremely tortuous coronaries, in which may be necessary
increased support afforded by the femoral approach. However, in current practice, PCI for calcified lesions
is performed indifferently by both radial and femoral arterial access, with the obvious advantages associated
with radial access in terms of risk of complications [39,40] . Extremely thin-walled radial sheaths are now
available to allow a 7F guide catheter to be held in the inner lumen while having an outer diameter equal to
that of a 6F sheath (GlideSheath Slender, Terumo Corp., Tokyo, Japan). Alternatively, a sheathless guiding
catheter may be used, which does not require a percutaneous introducer, and which has a 7.5F internal
working lumen with a smaller outer diameter than a 6F radial introducer (EauCath, ASAHI Intecc, Aichi,
Japan). For rotational atherectomy with a burr larger than 1.5 mm or when the coronary anatomy is
particularly complex, it is always good practice to use a guide catheter with a lumen greater than 6F, but a
1.75 burr can be used with 6F guide catheters without important limitations. For guidewire selection, it is
preferable to use non-hydrophilic guides (e.g., Hi-Torque Balance Middleweight, Abbott Vascular, Santa
Clara, CA, USA or Sion Blue, ASAHI Intecc or Runthrough NS, Terumo Corp.), as they provide better
tactile feedback, thereby reducing the risk of sub-intimal passage of the guidewire or coronary dissection. If
these guidewires are ineffective in crossing the calcified lesion, hydrophilic guidewires such as Sion (ASAHI
Intecc) and Runtrough NS Hypercoat (Terumo Corp.) or polymeric guidewires such as Pilot 50 (Abbott
Vascular) or Fielder FC can be used (ASAHI Intecc). The use of a balloon catheter or a micro-catheter can
provide greater support and control of the guidewire and facilitate passage through the calcified lesion,
especially if it is functionally occlusive.

Lesion preparation
Severely calcified lesions must be accurately prepared for stent implantation. In most cases, the difficulty in
advancing the devices across the calcified lesion and the high risk of stent under-expansion require
extensive plaque modification. Thus, it is intuitive that calcified lesions cannot be treated with direct stent
implantation. The techniques available for the treatment of calcifications can be classified into two groups
[36]
[Table 1]: “balloon-based” techniques and “ablative” techniques . The aim of “balloon-based” techniques
is not to ablate calcium but to increase plaque compliance, therefore allowing for optimal stent expansion.
The “ablative” techniques include Rotational Atherectomy (RA), Orbital Atherectomy (OA) and Excimer
Laser Coronary Atherectomy (ELCA) and theoretically determine the removal (debulking) of the
calcifications, with the aim of allowing an optimal stent expansion and apposition. IVUS and OCT have
actually demonstrated that the various ablative techniques act mainly by modifying the composition of the
plaque through their selective action on the calcific component, typically creating micro-fractures in the
parietal calcifications and dissection flaps, the presence of which is associated with a greater expansion of
the stent . It is much infrequent to observe effective tissue ablation with evidence of residual craters or
[41]
tunnels [42,43] .