Fig. 20.1
Configuration of the Wave 3S (Terumo, Heartrail II)
In PCI, it is important to achieve coaxiality of the GC and coronary artery in order to gain backup support. But there was no optimal GC to use in cases presenting difficulty in engagement because of, in particular, the many varieties in origin and course of the RCA compared to the LCA, and moreover, in the case of TRI, reasons such as tortuosity of the subclavian artery. This was the situation behind the development of the Wave 3S GC. As can be seen in Fig. 20.2, this GC can be used for various takeoffs and courses of the RCA.
Fig. 20.2
Wave 3S coaxiality by difference in RCA origin as viewed from the left anterior oblique view. (a) Low takeoff. (b) High takeoff
Because there are times when it is difficult to achieve sufficient backup support when the RCA is treated by right TRI, some operators favor treating the RCA by left TRI, and the LCA by right TRI. However, as the radial artery pulsation becomes weakened by multiple punctures, and because there are more than a few cases where it is not possible to puncture both the right and left radial arteries, it is believed that operators need to be trained to achieve backup support regardless of whether the approach is from the right or left radial artery.
In order to achieve sufficient GC backup support, a GC with a large-sized curve should generally be selected. For instance, in treatment that conventionally uses a JL4.0, if engagement using a GC with a one-size larger curve, such as a JL4.5, is possible, the second curve can touch the opposite side of the aortic wall to increase support.
20.2 Deep Engagement Technique
No matter what shape or size of GC is used, we sometimes experience cases in treatment of calcified lesions and highly tortuous lesions where stent delivery, and at times, even balloon delivery, is difficult due to insufficient backup support. As mentioned above, although TRI basically uses a 6 Fr GC, by acquiring proficiency in the deep engagement technique it would become possible to achieve stronger backup support than conventional use of a 7 Fr GC.
The deep engagement technique is often used in a tortuous RCA. In recent years, the delivery performance of balloons and stents have improved, and also small diameter inner catheters are able to reach deeper into the coronary artery using the mother-child catheter technique, which will be explained later. Due to these reasons, the employment of extreme deep engagement (Fig. 20.3) is decreasing. In general, in the deep engagement technique, after crossing a guidewire, the GC is advanced into the coronary artery while a balloon is inflated to provide anchoring. Because this poses the risk of dissection at the coronary ostium, it would be important to identify the coronary artery’s characteristics, course and morphology. When there is a stenosis at the coronary ostium, the operator may start by implanting a stent, which could make it easier to deeply engage the catheter, but on the other hand, the proximal stent could hamper distal stent delivery.
Fig. 20.3
Stent placement in a very tortuous RCA lesion through the deep engagement technique using 6Fr. Wave 3S. Severe tortuosity is seen in the proximal RCA (a). Through balloon anchoring, deep engagement to the mid portion of the RCA was possible (b). Angiogram after stent placement (c)
20.3 Parallel Wire Technique
The parallel wire technique is a conventional technique that is used when difficulty is encountered in device delivery during the treatment of tortuous lesions and calcified lesions. With only the additional insertion of a wire, the procedure itself is not a difficult one, making it an easy-to-select option when stent delivery is difficult in TRI as well. However, it must be understood that its effects are limited. It is also often effective in the tortuous lesions of flexible coronary arteries that can be straightened to some extent when a wire is inserted. On the other hand, in severely calcified lesions, this technique is often not successful even when there is no tortuosity present (Fig. 20.4).
Fig. 20.4
A case where the parallel wire technique was not successful. A lesion that is both severely calcified and tortuous is seen in the mid portion of the RCA. (a) before contrast injection, (b) after contrast injection). The tortuous portion would not straighten even when using the parallel wire technique, making stent delivery extremely difficult (c) stacking of the stent in front of the lesion. In a case like this, another technique to increase backup support should be taken
In addition, in TRI, which often uses a 6 Fr GC with a smaller inner diameter than a 7 Fr, the effects of the parallel wire technique could be diminished through an entanglement of the wires. To prevent this from occurring, insertion of the second wire should be done with a minimum amount of torque (Fig. 20.5). This is also an extremely important cautionary point in the balloon anchoring technique, which will be explained in the next section.
Fig. 20.5
How to prevent entanglement of guidewires in the parallel wire technique. Clearly keep the first wire separate, and anchor the wire using moist gauze. Be careful not to apply more than 360° of torque in one direction to the second wire
20.4 Balloon Anchoring Technique
The balloon anchoring technique aligns with the mother-child catheter technique (explained in the next section) as one of most effective techniques that can be taken in the treatment of severely calcified lesions and tortuous lesions by TRI, and is believed to be a technique that operators should by all means master. The procedure basically consists of inserting a wire into a side branch proximal to the target lesion, and while inflating a balloon in the side branch, advancing the stent (device) to the target lesion (Figs. 20.6 and 20.7). Even if the balloon used for anchoring is inflated at low pressures, it will be effective in most cases. Whenever possible, anchoring should take place in a section clear of lesions in order to prevent dissection in the side branch. In addition, in cases when the device cannot cross the lesion, its rebound may cause the wire in the side branch to slip deeply into the vessel, resulting in possible perforation of the vessel. Thus, the use of hydrophilic guidewires, tapering wires, and intermediate or stiffer wires as anchoring wires should be avoided whenever possible. Moreover, as was mentioned above, since entanglement of the wires will reduce the inherent effects of the balloon anchoring technique as well, insertion of the second wire must be done with a minimum amount of torque.
Fig. 20.6
Basic balloon anchoring technique. A wire is inserted into a side branch proximal to the target lesion, and while a balloon is inflated in the side branch, the stent (device) is advanced to the target lesion. Sufficient anchoring effects can be achieved in most cases at lower than regular inflation pressure in the side branch
Fig. 20.7
Balloon anchoring technique in a highly tortuous RCA lesion. A total occlusion is seen in the RCA mid portion in the pre-procedure angiogram (a). Since it was not possible to deliver a stent by a conventional method, a 2.0 mm balloon was inflated for anchoring in the RV branch, and a Driver 3.0/18 mm was advanced to successfully cross the lesion (b). Final angiogram (c). A 7 Fr GC was used in this case. The stent delivery system that was employed had a large outer diameter that made it impossible to use a 6 Fr GC. Currently, nearly all stent delivery systems, for both DES and BMS, can beused for balloon anchoring technique through a 6 Fr. GC
If there is no suitable side branch proximal to the target lesion, there are cases where it is effective to have one more wire inserted in the target vessel for anchoring in the distal portion of the target lesion (Fig. 20.8).
