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Page 4 of 11 Paraggio et al. Vessel Plus 2019;3:12 I http://dx.doi.org/10.20517/2574-1209.2018.72

Figure 1. Comparative chart of different guiding catheter/GuideLiner systems which may be considered to perform percutaneous
coronary interventions through radial approach. On X-axis outer diameter in millimeters; on Y-axis inner diameter in inches

often used to minimize dampening, but should not be used in unprotected left main as they can provide a
false sense of security and cause severe ischemia. More recently, several mother-in-child devices have been
introduced to maximize passive support during CTO and even complex PCI. The GuideLiner catheters
[20]
(Vascular Solutions, Inc., MN, USA) were the first to be introduced in 2009 . All these devices are coaxial
“mother and child” guiding catheter extension delivered through a standard guiding catheter on a monorail
system with flexible distal extension and radiopaque markers near the distal tip. These characteristics,
together with a tight design, allow deep intubation into the coronary arteries without slippage thus favoring
the delivering of materials behind areas of narrowing or tortuosity, which could reduce GC backup [Figure 1].

On the other hand, active support could be improved with some techniques developed specifically for CTO
procedures. A first unspecific option does exist and consist to perform a deep intubation of the GC. However,
this old technique carries out a consistent risk of proximal vessel dissection and has been overcome by using
mother-in-child devices. More recently, a new technique, called “mother-daughter-granddaughter” has been
developed using a 6F Guideliner into an 8F Guideliner to allow navigation of very tortuous segments, such
as saphenous graft, unfolding the equipment rather than pushing it. However, these technique should be
handled more carefully as the risk of coronary dissection in very high.

The widespread use of 7F or 8F GC led to the development of another active support option: the “anchoring
[21]
balloon” technique . Sometimes antegrade guidewire crossing of a CTO lesions is not followed by successful
advance of microcatheters or balloon through the lesion. The first step of such technique is to wire a risk free
side branch target before the lesion. Subsequently, inflating a balloon into the side branch provided a stable
“anchor” which increase support to advance materials through CTO. This technique could be also useful in
daily PCI procedures, in any case of difficult advancement of materials (such as balloon or stents) through
tight or calcified lesion. More recently, some variations have been introduced to the original “anchoring
balloon” technique. Out of these, the most used technique in daily PCI scenario is the distal mother-in-child
[22]
devices anchoring . In any case of difficult stent delivery, the mother-in-child device is advanced just before
or even through the target lesion over a distally placed inflated balloon. Such balloon was then deinflated and
withdrawn safely and the selected stent could be delivered at the site of the lesion [Figure 2].

In any case of highly complex PCI situations, the use of mother-in-child devices to increase passive support
or the application of active support techniques could improve success rate, even in case of PCI that may have
previously been considered technically unapproachable.