Active support
Passive support
Guide catheter tip
Soft tips
Long tipped
Guide catheter shape
Can be altered to accommodate aortic root
Rests on aortic valve or opposite wall of the aorta
Guide catheter size
Active support decreases with larger guide catheter size
Passive support increases with larger guide catheter size
Curves
More flexible primary curves
Stiffer primary curves
Risk of aortic or ostial coronary dissection
Low
High
Side holed catheters are sometimes essential when there is proximal disease of the coronary and if the pressure wave form dampens on engaging the coronary. The major advantage with the use of guide catheters that have side holes is the ability to monitor arterial pressure although anterograde flow into the vessel may not be adequate and patients may still get ischemic even with an adequate wave form and a side holed catheter. Theoretically, the risk of a hydraulic coronary dissection is also reduced with side holes. The disadvantage of side holed catheters is the additional contrast use and the kinking of the catheter that can occur at the site of the side holes. It is not recommended to use side holed catheters in the left coronaries unless there is ostial left main disease that prevents safe engagement of the guide.
Guide Catheter Extensions
Guide extensions provide additional guide catheter support by deep intubation of the coronary vessels. Examples include the HeartRail (Terumo, Japan), Guideliner (Vascular Solutions, US) or Guidezilla (Boston Scientific, US) devices which are designed for deep seating in coronary arteries, thereby contributing to increased back-up support. They have also been shown to boost success rates in CTO PCI [8]. Guide catheter extensions are particularly useful when the takeoff of the coronary ostium prevents coaxial engagement of the guiding catheter. The deep-intubation of the target coronary vessel by the softer, flexible extension catheter ensures coaxial alignment, alleviating this problem. For example, the GuideLiner catheter consists of a flexible 20 cm straight guide extension connected to a stainless-steel push shaft, allowing for additional support within the coronary vessel (see Chap. 3). It allows deep engagement into the coronary vessel, providing backup support when device delivery is attempted through challenging anatomy. The Guidezilla guide extension catheter has a 1 × 1 braid that provides improved back-up guide support without over-straightening the vessel. The HeartRail coronary guiding catheter extension is a coaxial system with a flexible shaft that provides track ability even in tortuous vessels. Its increased lumen size enables lower device friction for delivery of devices to and beyond the lesion. When using the HeartRail or other extension catheters, successful stent delivery is contingent upon the intubation depth, showing markedly improved success rates with depth >2 cm [8]. With all the guide catheter extensions, the support provided is exponentially related to the length seated within the coronary artery. Caution needs to be exercised with their use because of reports of stent shearing and entanglement; proximal vessel dissection and even loss of the distal tip of the catheter in the vessel [9]. These catheter extensions also have niche roles in retrograde CTO PCI [10].
Anchoring Support
Sometimes modifying the guiding catheter shape is not enough to provide the necessary support needed to complete CTO PCI.
In such instances anchoring techniques are required.
(a)
Side branch Anchor Technique:
A workhorse guidewire is advanced into a sidebranch (usually a conus or acute marginal in the setting of the RCA and a diagonal for the LAD) followed by advancing a small diameter balloon like a 1.5 mm or 2 mm balloon. The balloon is inflated at 6–8 atmospheres anchoring the guide in the vessel (Fig. 12.1a). This then facilitates advancement of balloons and micro catheters. Side branch anchor technique offers the advantage of contrast injection and unobstructed access to the CTO [11].
Fig. 12.1
Different anchoring modalities for guide catheter stabilization. (a) Anchoring of a balloon in the side branch proximal to the lesion. (b) Sub-intimal distal anchoring of a balloon in the PDA distal to the lesion-using the subintimal space
(b)
Proximal vessel anchor technique:
Sometimes there are no suitable side branches into which a balloon can be safely inflated. In such situations, inflation of a semi-compliant balloon at nominal inflation pressures in the proximal vessel over a buddy wire can also be done to enhance support within the system.
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