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Colombo et al. Vessel Plus 2019;3:29 I http://dx.doi.org/10.20517/2574-1209.2019.005 Page 5 of 9

Figure 2. A:heavily calcified mid RCA CTO; B: epicardial collateral (yellow arrows) from LCx was navigated wih Sion Black wire; C:
then CTO was crossed retrograde with Gaia 3 wire that re-entered in right guiding catheter but the microcatheter wasn’t able to cross
retrograde depite double trapping; D: clinical destabilization suddenly occurred with chest pain and hypotension: angiography showed LM
dissection with LAD occlusion (circle); E: LM-LAD stenting after LAD wiring; F: final angiographic result: patency of LAD and LCx, aborted
CTO PCI. CTO: chronic total occlusions; RCA: right coronary artery; LAD: left anterior descending; LCx: left circumflex; LM: left main

One last consideration should be made on epicardial perforations occurring in patients with prior coronary
artery bypass graft. Typically, bleeding may be focal and contained in spaces due to prior adhesions and
surgical scarring, without tamponade. Nevertheless local chamber compression (i.e., atria) with focal
tamponade not amenable to pericardiocentesis and requiring surgical intervention, can still occur.

Despite new materials and techniques availability in the prevention and management of CPs, a crucial
role is played by the identification of the clinical/angiographic predisposing factors. A recent study of
[15]
Kinnaird et al. investigates the principals features related to CPs during CTO PCI. Older age, female
sex and previous PCI were found as main individual risk factors. Procedural factors associated with
an increased risk of perforation were Crossboss/Stingray use, rotational or laser atherectomy, and
microcatheter use.

DONOR VESSEL INJURY (DISSECTION AND/OR OCCLUSION)
Abrupt donor vessel injury represent a feared and unique complication occurring during retrograde CTO
[16]
PCI. Its estimated incidence is 1.1%-1.8% . Leading mechanism of donor vessel injury are dissection
(most common), thrombus formation/embolization, spasm or accidental air injection. Main effect of this
complication is myocardial ischemia and its extension is related to the size of myocardium supplied. Thus,
chest pain, electrocardiographic changes, hypotension and arrhythmias are common clinical features.
Clinical and interventional management depends on the leading mechanism.

Dissection: usually retrograde CTO procedures require aggressive guiding catheters to gain the maximum
support but at the expense of potential proximal donor vessel dissection. Furthermore specific attention
must be paid in withdrawing equipment (wires, microcatheters), maneuver than can cause “deep
intubation” and consequent dissection [Figure 2]. We recommend to place a protection guidewire along
LAD at the beginning of the procedure, when retrograde approach from left coronary system is needed.