Y‐connector is attached to Kiwami® (child) which was inserted in the 6 or 7 Fr (mother) catheter. Because the effective length of Kiwami® is 120 cm, the projected length from the mother catheter differs depending on the length of mother catheter used [12]. The 4 Fr‐in‐6 Fr Kiwami® catheter is probably the most deliverable among the GC extensions, but has the smallest lumen (0.050 inch) and requires meticulous attention to details to avoid air embolism [13].
Guide catheter extensions
In the GuideLiner® catheter (Teleflex‐Vascular Solutions, Maple Grove, MN, USA) a coaxial short distal soft catheter is mounted at the tip of a long stainless‐steel rod, which extends outside the guide catheter. This enables deep intubation of the coronary artery to achieve extra support and improve coaxial alignment. It has a coaxial 20 cm long catheter with a radiopaque marker situated 2.7 mm from the tip from the tip, joined to a 125 cm compact metal hypotube by means of a ring (“collar”, made of metal in the first version and replaced by a lubricious polymer in the V2 version), which can be deployed through the existing Y‐adapter for rapid exchange delivery. The device is available in three sizes: 5‐in‐6 (0.056 inch internal diameter (ID)), 6‐in‐7 (0.062 inch ID), and 7‐in‐8 (0.071 inch ID). Its monorail design permits rapid exchange and offers important advantages over its predecessors, the “five‐in‐six mother and child” catheters Heartrail II®, which had a coaxial system that made their utilization more demanding [11]. Furthermore, rapid exchange helps with deployment through the existing hemostatic valve without extending the guiding catheter length, and so does not limit the useable length of balloons and wires. Other Companies designed similar catheters such as the Guidezilla™ (Boston Scientific, Marlbourough, MA, USA), Telescope (Medtronic, Minneapolis, MN, USA), Gideon (IVS, Maastricht, The Netherlands), claiming more lubricious coatings or smoother connections between hypotube and distal catheter. The Guidezilla is probably the most widely used guide extension after the GuideLiner, is mounted on a monorail system, which extends the guide catheter and enables deep intubation of the coronary artery. It is made of a distal end of 25 cm covered by a hydrophilic polymer, joined to a 120‐cm compact metal hypotube. The distal flexible extension consists of a pair of radiopaque markers, the first situated 2 mm from the tip and the second 3 mm from the transition collar. The device is available in one size 5‐in‐6 and compatible with guide catheter ≥6 Fr. An additional system, with sizes compatible also with 5 Fr guiding catheters, is the Guidion rapid exchange guide extension catheter (IMVS, Roden, the Netherlands).
De Man et al. [14], published results from the Twente GuideLiner Registry identifying three primary indications for the use of the device: improvement of back‐up and facilitated stent delivery (59%), more selective contrast injection (13%), and improvement of alignment of the guide (29%). Moreover, they found a device and procedural success rate of 93% and 91%, respectively, without major complications and a small incidence of minor complications (3%). The safety and efficacy of utilizing the GuideLiner monorail catheter to treat complex lesions was confirmed in recent experience published by Chan et al and Fabris et al. [15,16], showing good performance of the device in the settings of bypass graft intervention, bifurcation lesions, and chronic total occlusions. In order to avoid damage of the proximal vessel, especially in case of non‐coaxial alignment of the coronary ostium and extreme proximal vessel tortuosity (e.g. a shepherd’s crook’s origin of the RCA”), a balloon advanced distally can be used to reduce the chance of damaging the ostium and the proximal vessel by acting as centering rail). If the guide extension does not advance this can be caused by vessel tortuosity and poor GC back‐up and solved inflating the distal balloon to gently attract it or can be caused by presence of proximal stenoses or calcifications, in need of effective predilatation.
Guidewire selection
Guidewires are required to cross the target lesion and to provide support for the delivery of balloons, stents, and other devices while at the same time minimizing the risk of vessel trauma. A guidewire needs to be steerable, visible, flexible, lubricious, and supportive. There is no single wire that has the perfect combination of all these characteristics. Variations in guidewire components have produced a wide range of wires suitable for different anatomies and lesion characteristics. Wire selection depends on which features are thought to optimally facilitate angioplasty for a given clinical and angiographic scenario.
Guidewires typically come in 180–195 cm length for rapid exchange (Rx) use. Long (300 cm) wires have become almost obsolete since the technique of balloon trapping has gained wide application to remove or insert OTW balloons or microcatheters. The only limitation of this technique is its inapplicability in very small guiding catheters (5 Fr) or when a guide extension is present (except Trapliner). Anyway, almost all wires (Abbott, Asahi, Terumo) have wire extensions that can be fixed at the distal end to increase wire length. Most wires (Abbott, Asahi, Terumo) anyway allow fitting at the distal end a dedicated extension wire. Finally, maintaining pressure with an Indeflator connected to the central lumen of the OTW microcatheter or balloon catheter allows flushing it out keeping the wire in place (Nanto technique).
Guidewires consist of a central core of stainless steel or nitinol alloy that makes up the proximal section of the wire, approximately 145 cm long, and which tapers toward a distal section measuring 35–40 cm. This distal segment has a further outer covering of either a fine coil spring consisting of tungsten, platinum, or stainless steel, or a polymer coating loaded with a material such as tungsten to improve radiopacity. The tip often has a lubricious coating that is either hydrophobic or hydrophilic (Figure 5.7). Using stainless steel as the core material improves the steerability and torque control, but steel wires can be deformed by tortuosity and cannot be reshaped. A nitinol core also offers excellent torque control, but the wire retains its shape better and can be reshaped if deformed. Increasing the core diameter increases shaft support (Figure 5.8). There is often a short transition zone between the tapered distal segment whereas some wires have a very gradually tapering central core, which tends to track better around tortuous anatomies and prolapse less when there is extreme angulation (Figure 5.8). Features of the functional design of guidewires are listed in Table 5.4. Guidewires can be classified into general purpose or “workhorse” and dedicated wires (Table 5.5).
Figure 5.8 The components of a rapid exchange balloon catheter.
Table 5.4 The selection of a guidewire depends on the characteristics required to deal with lesion complexity or particular vessel characteristics. The characteristics of guidewires can be altered by modifying specific components during the production process.
| Flexibility | Flexible wires can better negotiate severe tortuosity or angulation without deformation. | Shaft core material (nitinol offers greater flexibility and shape retention), core thickness (thinner core = more flexible). |
| Support | Improved equipment delivery when hampered by angulation, tortuosity, lesion severity, calcification. | Shaft core material, core thickness. |
| Steerability is a function of: | ||
| Torque transmission | ||
