Читать книгу Interventional Cardiology - Группа авторов - Страница 141

Microcatheters constitute over the wire support systems that contribute to the success of both antegrade and retrograde recanalization techniques. They were specifically developed to enhance lesion crossing and can substantially increase the support offered to the guidewire when they are engaged within the lesion. Microcatheters also allow reshaping or changing the guidewire without losing the distal position. They prevent prolapse of the guidewire and improve its penetration ability. Microcatheters can also straighten a tortuous artery proximal to the lesion and increase the guidewire torque. They can also be used to inject contrast dye to visualize the distal vessel. Due to their small profile, they can also cross the lesion when small balloons fail to do so. A wide range of microcatheters are currently available and they can be divided into different categories according to their characteristics:

 Large diameter microcatheters, such as the Corsair (Asahi Intecc, Nagoya, Japan), Turnpike and Turnpike Spiral (Teleflex, Wayne, PA, USA). Larger microcatheters are usually used to improve guidewire support during antegrade CTO crossing.

 Small diameter microcatheters, such as the Finecross (Terumo, Somerset, New Jersey), Caravel (AsahiIntecc), Turnpike LP (Teleflex), and Micro 14 (BTG, London, United Kingdom). Like the larger ones, they are used to increase guidewire support but, thanks to their smaller diameter, they are also particularly useful to negotiate tortuosity and cross severe lesions.

 Angulated microcatheters, such as the Supercross (Teleflex) and Venture (Teleflex), used to access side branches. Recently, the steerable microcatheter (SwiftNINJA, Sumitomo Bakelite, Tokyo, Japan), which has a remote controlled flexible tip manipulated using a dial in the handgrip, was developed, enabling the operator to change the angle of the microcatheter tip manually, and potentially makes selective catheterisation easier [29]

 Dual lumen microcatheters, such as the TwinPass and TwinPassTorque (Teleflex); Sasuke (Asahi), NHancer Rx (IMDS, The Netherlands). They consist of a rapid delivery system exchange in the distal segment associated with an OTW lumen along the catheter. Although each device has its own peculiar characteristics, all these devices share a common feature, that is the presence of two lumens, whose purpose is to allow precise and independent handling of two different guidewires. The rapid exchange distal port is at the distal end of the catheter, while the OTW lumen starts some mm more proximally and runs the whole length of the catheter. Two radiopaque markers are positioned in order to identify the exit ports of both lumens. The role of dual lumen microcatheters has been expanding [30,31] and they can be used for: parallel wire technique; antegrade wiring of CTOs with side branch at the proximal cap; wiring distal true lumen without losing access to a distal side branch near the distal cap; antegrade wiring of the distal true lumen if the externalized retrograde guidewire crossed a collateral close to the distal.

 Plaque modification microcatheters, such as the Tornus (Asahi Intecc), and Turnpike Gold (Teleflex): they are specifically designed for difficult crossing cases and may enlarge a channel through an uncrossable lesions after successful guidewire crossing. Tornus is advanced rotating counterclockwise, whereas the Turnpike Gold is advanced by rotating clockwise. Rotating in the opposite direction is needed for removal.