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“Balloon-Uncrossable” and “Balloon-Undilatable” Chronic Total Occlusions
8.1
Balloon-Uncrossable Lesions
See Online Cases 1 , 5 , 15 , 18 , 27 , 30 , 31 , 47 , 49 , 52 , 53 , 57 , 73 , 82 .
Goal
Cross the chronic total occlusion (CTO) with a balloon (or microcatheter) after successful guidewire crossing.
The main reason for failure of CTO interventions is inability to cross the occlusion with a guidewire. However, in some cases, a balloon cannot cross the lesion after successful guidewire crossing and confirmation of guidewire placement into the distal true lumen. Such lesions are called balloon-uncrossable CTOs, and represent 6%–9% of CTO lesions.
Fig. 8.1 outlines a step-by-step algorithm for approaching such lesions.
Step 1 Advance and Inflate a Small Balloon, Grenadoplasty
How?
Step 1a Small Balloons
- a.
Use single-marker, rapid-exchange compliant balloons with low crossing profile (1.20, 1.25, and 1.5 mm in diameter) and long length (20–30 mm). The balloon profile is highest at the marker segment, hence longer balloons may allow for deeper lesion penetration before the balloon marker reaches the uncrossable segment of the CTO.
- b.
If the balloon stops advancing, it can be inflated while maintaining forward pressure. This may dilate the proximal cap and allow lesion crossing, sometimes even with the same balloon (balloon-wedge technique).
- c.
If the balloon fails to advance after inflation, one can try with a new small balloon (since balloons do not return to their original profile after inflation), or one manufactured by another company, as different crossing profile and tip characteristics may assist in crossing. Rapid-exchange balloon catheters allow more pushability into the lesion.
- d.
Alternatively, one can attempt crossing with a larger 2.5–3.0 mm diameter rapid-exchange balloon. Sometimes inflation with a larger diameter balloon just proximal to the CTO lesion will disrupt the architecture of the proximal CTO cap enough to allow subsequent passage of a small profile balloon or microcatheter.
Step 1b Threader and Glider Balloons
- a.
The Threader ( Section 2.8.1 , Fig. 2.53 , Boston Scientific) is a combined balloon and microcatheter with excellent penetrating capacity and is easy to use (same as a small balloon as described in Step 1a). It has a hydrophilic coating and 0.017″ lesion entry profile.
- b.
The Threader is available in both rapid-exchange and over-the-wire versions. The rapid-exchange Threader is preferred to the over-the-wire version for balloon-uncrossable lesions, as it has more penetrating capacity (likely due to stiffer shaft). On the other hand, the over-the-wire Threader allows guidewire changes and contrast injection.
- c.
The Glider balloon (Trireme Medical) has a beveled tip and was developed to cross through the struts of stents during bifurcation stenting, but can also be useful in hard-to-cross lesions, as it can be torqued to present different tip configurations to the lesion.
What Can Go Wrong?
- a.
Guide catheter and guidewire position can be lost during attempts to advance the balloon or Threader. Carefully monitor the guide catheter position and stop advancing if the guide catheter starts backing out of the coronary ostium or if the distal wire position is being compromised.
- b.
Injury of the distal target vessel can occur (dissection or perforation) due to significant distal guidewire movement (see-saw action of wire with forward push of balloon and retraction of force), especially when stiff (such as Confianza Pro 12) or polymer-jacketed (such as the Pilot 200) guidewires are used.
- c.
Balloon entrapment can occur inside the occlusion, although this is highly unlikely.
Step 1c Grenadoplasty (Intentional Balloon Rupture; also Called Balloon-Assisted Microdissection)
This is a simple, safe, and often effective technique, which is increasingly being used in the treatment algorithm for balloon-uncrossable lesions.
How?
A small (1.20–1.50 mm) balloon is advanced as far as possible into the lesion and inflated at high pressure until it ruptures ( Fig. 8.2 ). When the balloon ruptures, suction should be immediately applied through the inflating device. The balloon rupture can often modify the plaque, resulting in successful crossing with a new balloon.
What Can Go Wrong?
- a.
Proximal vessel dissection and perforation. This is extremely unlikely when small (1.20–1.50 mm) balloons are used. Larger balloons should not be used for grenadoplasty.
- b.
The balloon should be meticulously prepared to empty all air and hence minimize the risk for air embolism.
- c.
Watching the indeflator rather than the screen allows more rapid deflation of the balloon as soon as rupture has occurred. This will reduce the chance of pinhole contrast injury from the rupture site of the balloon.
- d.
One may encounter difficulty removing the ruptured balloon. In some cases the ruptured balloon becomes entangled with the guidewire, requiring removal of both, hence losing guidewire position. This is more likely to happen with the 1.25 mm balloons, hence utilizing 1.5 mm diameter balloons is recommended.
Step 2 Microcatheter Advancement, Carlino, Wire-Cutting, Wire Puncture, and Increasing Guide Catheter Support
Treating the balloon-uncrossable lesion can be achieved using a combination of plaque modification (e.g., using a microcatheter) and increasing guide catheter support.
Step 2a Microcatheter Advancement
How?
- a.
The concept behind use of a microcatheter is that advancement of a microcatheter through the CTO can modify the occlusion, enabling subsequent crossing with a balloon.
- b.
There are several microcatheters that can be utilized as described in Chapter 2 .
- c.
The following microcatheters are especially designed for balloon-uncrossable lesions:
- ●
The Tornus catheter ( Section 2.8.2 ) was designed for advancing through calcified and difficult-to-penetrate lesions and should be advanced using counterclockwise rotation and withdrawn using clockwise rotation.
- ●
The Turnpike Spiral and Turnpike Gold catheters ( Section 2.8.2 ) were also designed with threads to screw into the lesion and modify it. In contrast to the Tornus catheter, they are advanced by turning clockwise and withdrawn by turning counterclockwise.
- ●
- d.
Standard microcatheters can also be used:
- ●
The Corsair and Corsair Pro catheter ( Section 2.4.2 ) can be advanced by rotating in either direction (in contrast to the Tornus catheter).
- ●
The Turnpike and Turnpike LP catheter ( Section 2.4.6 ) can also be rotated in either direction.
- ●
Similarly, the Finecross ( Section 2.4.4 ) or Micro 14 ( Section 2.4.5 ) can be rotated in either direction, although rotation may be challenging to achieve.
- ●
The Caravel ( Section 2.4.3 ) is a low profile microcatheter, but is not designed for aggressive torqueing as the Corsair and Turnpike.
- ●
- e.
If successful advancement of a microcatheter is achieved, a balloon can often subsequently cross the lesion. Alternatively, the guidewire could be exchanged for a more supportive guidewire or an atherectomy wire, if the latter is planned as the next lesion preparation step.
What Can Go Wrong?
- a.
Guide catheter and guidewire position may be lost with aggressive pushing of the microcatheters.
- b.
Distal vessel injury (dissection and/or perforation) can occur from uncontrolled guidewire movement during microcatheter advancement attempts.
- c.
The microcatheter can get damaged if overtorqued, leading to catheter entrapment or tip/shaft breakage. Rotation should not exceed 10 turns before allowing the catheter to unwind. A guidewire should always be kept within the microcatheter lumen to prevent kinking and possible entrapment. If the tip of the microcatheter breaks off it can become entrapped in the lesion ( Online Case 87 ).
- d.
Rarely excessive manipulation of the microcatheter can disrupt the device and/or the guidewire and lock both devices together, requiring withdrawal of both (See Chapter 2 , Fig. 2.21 ). A polymer-jacketed guidewire can sometimes be advanced through the track that has been established, allowing the crossing attempts to restart.
Step 2b Carlino
The Carlino technique is described in detail in Section 5.6.3 .
How?
- a.
A microcatheter is advanced as close to the proximal cap as possible.
- b.
A small amount of contrast (0.5–1.0 mL) is injected through the microcatheter under cineangiography.
- c.
Contrast injection can cause microdissection and facilitate subsequent advancement of a balloon or a microcatheter.
What Can Go Wrong?
- a.
Perforation, if a large amount of contrast is injected and if the catheter is inserted into a small side branch. The risk is low with injection of a small amount of contrast.
Step 2c Wire-Cutting ( Fig. 8.3 )
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