Fig. 18.1
(a) 73-year old female patient. Right subclavian artery showed marked tortuosity and loop. (b) However, the left subclavian artery was relatively straight. (c) The LCA was cannulated by a 6 French EBU 3.5 guiding catheter (Launcher) through the left radial artery. Two CTO lesions were in the proximal LCX and distal LAD. (d) LAD also showed 2 critical narrowings in the proximal and 1 CTO lesion in the distal parts. (e) Final angiogram after stenting for both arteries
18.1.5 Use of Microcatheter
In angioplasty for CTO lesions, guidewire should be used not with “bare-wire technique” but always with microcatheter. This is recommended because;
- 1.
Guidewires can be changed quickly and easily.
- 2.
Reshaping of the tip of guidewires is easy.
- 3.
By adjusting the length of guidewire protruding out of microcatheter, tip stiffness of guidewires can be controlled.
- 4.
Better torque transmission to the distal tip of guidewire can be achieved especially through tortuous coronary arteries.
Between the over-the-wire balloon catheter and microcatheter, the use of latter one is my recommended, because its tip is softer and guidewire manipulation is easier than the first in general.
18.1.6 Guidewire Selection
Guidewires specifically designed for CTO lesions can be classified into 3 major groups;
- 1.
Category I: Plastic-jacket hydrophilic tapered-tip guidewires: Fielder-XT, -XTR, -XTA (ASAHI Intecc), Wizard-78, -1, 3 (Japan Lifeline), etc.
- 2.
Category II: Non-plastic jacket blunt end guidewires: Miracle-3, -6, -12, -Ultimate (ASAHI Intecc)
- 3.
Category III: Non-plastic jacket tapered-tip guidewires: Gaia-First, -Second, -Third, Conquest-Pro 9, 12, 8–20 (ASAHI Intecc)
Based on the pathological findings in CTO lesions (described bellow), it is rational to start from plastic-jacket hydrophilic tapered-tip soft-end guidewires, which include Fielder-XT, -XTR or –XTA in Category I [3]. If these wires cannot pass the lesion, the wires should be quickly changed to Category II or III wires according to the lesion characteristics felt by the tip of Category I guidewires. If the lesion contains much calcification, Category II guidewires are preferred. Instead, if the lesion does not contain much calcification or target distal artery is clear, Category III guidewires are chosen.
18.2 Various Techniques in Angioplasty for CTO Lesions
18.2.1 Double Guidewire (Parallel Guidewire) Technique
Pathological examination of CTO lesions indicate the presence of small vascular channels partly or completely connecting from the proximal to the distal ends of the CTO lesions [4]. Their diameters are ranging between 160 and 230 μm. The channels are frequently ends at the sidewall of the coronary artery or connecting to the side branches far proximal to the distal end of the CTO lesion. The channels themselves cannot bee seen on fluoroscopy because of tiny diameters. Computed tomography of coronary arteries may be helpful especially to identify the presence of calcification within the lesion [5] (Fig. 18.2). A PCI guidewire can easily advance into these micro channels, which are ending at the sidewall of the coronary artery and results in forming intimal dissection.
Fig. 18.2
Tapered-tip guidewire in PCI for CTO Lesions
Double guidewire technique is the best way to overcome this situation. If the guidewire goes into the false lumen or side branches, do not pull out but leave it there. While leaving the 1st guidewire there, you have to take the 2nd guidewire. You have to train yourself hard, so that you can trace the exactly same pathway by the 2nd guidewire as the 1st guidewire. After the tip of the 2nd guidewire reaches the point, where the 1st guidewire seems diverting from the true lumen, you intentionally direct the tip of the 2nd guidewire into the true lumen. This is the concept of “Double Guidewire Technique” (Fig. 18.3).
Fig. 18.3
Double Guidewire Technique in CTO Lesions
Three rationales can be listed for the mechanism of double guidewire technique. First, the 1st guidewire occludes the entry into the false lumen, and the 2nd guidewire can advance along the true lumen. Second, the 1st guidewire works as a landmark for the manipulation of the 2nd guidewire. Last, the 1st guidewire can straighten the tortuous coronary artery or change its geometry, which makes the guidewire manipulation easier.
Considering these three rationales, the proper strategies in double guidewire technique can be reached as follows:
- 1.
Do not manipulate the 1st guidewire too much within the false lumen. This maneuver will expand the subintimal space, and the subsequent attempts by using the 2nd guidewire to find the true lumen become more difficult.
- 2.
Take the penetrating technique for the 2nd guidewire to find the true lumen even after the drilling technique for the 1st guidewire.
- 3.
Take the 2nd guidewire stiffer than the 1st one in order to achieve the better torque transmission and penetration abilities.
- 4.
Always take a microcatheter with the 2nd guidewire. The use of the microcatheter prevents the twisting of the two guidewires and enables the fine torque control for the 2nd guidewire.
18.2.2 Triple Guidewire Technique (Fig. 18.4)
Fig. 18.4
Triple Guidewire Technique (a) Both two wires are in the false lumen. (b) Three wires are overlayed within the circle. (c) After successful stenting
If the double guidewire technique fails, the 3rd guidewire can be applied while leaving the previous two guidewires in the false lumen. The handling of the 3rd guidewire is more difficult compared to double guidewire technique, since the guidewires easily tend to be twisted each other. To prevent this twisting, the simultaneous use of two or three microcatheters is necessary, which requires at least six French (for two microcatheters) or seven French (for tree microcatheters) guiding catheters.
18.2.3 Side Branch Technique (Fig. 18.5)
Fig. 18.5
Side-Branch Technique (a) CTO lesion in mid right coronary artery. (b) Antegrade approach with a stiff guidewire. (c) Starting double wire technique. (d) One of the double wires passed into a side branch distal to the CTO lesion. (e) The wire was clearly in the right ventricular branch. Dissection is clearly identified. (f) A 1.5-mm balloon dilated to the branch. (g)After the balloon dilatation with a 1.5-mm balloon to the side branch. Faint antegrade filling through the CTO lesion can be seen. (h) Final angiogram
If a guidewire successfully penetrates the proximal cap of the CTO lesion and entered into the side branch but not crossed the lesion completely, it is recommended to take a 1.5-mm balloon and dilate the lesion to the side branch. After this balloon dilatation, you can ensure the route at lest to the side branch, and the re-wiring to the distal true lumen becomes easier. Important tips for the side branch technique include:
- 1.
Before you get convinced that the guidewire is really in the lumen of a side branch, do not attempt this technique.
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