Page 126 - Read Online

Page 8 of 11 Paraggio et al. Vessel Plus 2019;3:12 I http://dx.doi.org/10.20517/2574-1209.2018.72

is inflated at 4 atm and lithotripsy cicle in activated and pulses once per second for ten seconds (for a
maximum of 8 repeatable cycles), thus cracking intraplaque calcium. This device has the potential to become
[25]
a cornerstone in PCI, but only limited clinical data about outcome and safety are available and further
randomized trials are needed. Another valuable option is the employment of recent developed high pressure,
non-compliant balloons, such as OPN NC (SIS Medical, Switzerland) which could be inflated till 35-40
ATM, usually for about 30-60 seconds. Moreover, Angiosculpt (AngioScore, Inc.), a semi-compliant balloon
covered by three nitinol coils, have been recently developed and represents a sort of evolution of cutting
balloon with lower profile and higher number of cuts by millimeter of plaque.

In common everyday practice, complex fibro-calcific coronary lesions still represent a challenge for
the interventional cardiologist and commonly require adjunctive techniques and devices to facilitate
successful PCI. However, only correct and experienced employment of such devices could lower the risk
of complications, especially more catastrophic ones. Therefore, all the above descripted devices should be
available in cath lab and specific training programs should be attended by single operators.

RADIATION EXPOSURE IN THE CATH LAB: FACING THE PUBLIC ENEMY
Over the past decade, CTO interventions progressively spread all over the world leading to an increase
awareness of radiation exposure. CTO procedures are quite often long and complex procedures with
[11]
associated longer fluoroscopy times, as reported in several registries . However, the absence, among
interventional cardiologists, of consciousness of radiation injuries lead to development of a position paper
[26]
about medical radiation in cardiovascular imaging . Radiation-associated complications can be categorized
as deterministic (which have a threshold above which injury occurs, e.g., skin injury) and stochastic (that
have no threshold for injury to occur, e.g. cancer, infertility). Nowadays, the accepted threshold for skin
injuries is 5 Gray, so operators should follow the so-called ALARA rule (radiation as low as reasonably
acceptable) in order to minimize radiation injuries to the patient. Therefore, moving from CTO procedures,
some tricks to reduce radiation exposure are now commonly followed in every day practice: (1) reduction
of the fluoroscopy frame rate from 15/s to 7.5/s (probably the most effective way); (2) use of fluoro-store
function; and (3) optimization of x-ray tube collimation.

PROCEDURAL COMPLICATIONS: LESSONS LEARNED FROM CTO PROCEDURES
[27]
In the setting of CTO interventions, the incidence of complication is usually higher than everyday PCI .
Perforation, acute vessel thrombosis and device entrapment are the most common cardiac complications
and are more common during retrograde procedures. Moreover, extracardiac complications, such as arterial
embolization, radiation injury, contrast induced nephropathy and vascular access complication should be
taken into account when performing both CTO procedures and everyday PCI.

In the everyday PCI setting, acute vessel thrombosis is the most common cardiac complication and could be
caused by five main mechanisms: dissection, new thrombus formation, no reflow, inadvertent air injection
[28]
and vasospasm . Coronary dissection usually happens in long, complex and calcific lesions and rarely cause
vessel closure. Moreover, in the vast majority of cases, a guidewire could be advanced throughout the vessel
true lumen and this complication is easily managed by stent deployment. Seldom, acute coronary dissection
followed by abrupt vessel closure could be caused by sub intimal tracking of hydrophilic guidewire with
some difficulties to re-gain vessel true lumen and perform PCI. In such cases, the use of stiffer and/or easily
directing CTO guidewires in experienced hands could be very useful even in combination with dissection
and re-entry techniques.

Nowadays, arterial perforation is still the most common interventional cardiologist’s nightmare and is not
only restricted to CTO procedures. The incidence of coronary artery perforation is less than 1%, but is a very