The micro catheter is a very small diameter reinforced catheter with no strict size definition, but is often empirically referred to as a microcatheter with an outside diameter of 0.70 to 1.30 mm. Microcatheters can be used for guidewire support/exchange, passage of lesions, delivery of embolic agents, stenting, etc.
The microcatheter is composed of a base layer of etched PTFE Liner , a middle layer of stainless steel woven mesh or nickel-titanium spring, and an outer layer of Pebax liner.
The head end of the microcatheter comes with a developer ring for easy positioning and consists of a handle (seat), strain relief sleeve, body, and marker. The body is designed and manufactured to play a key role in the performance of the microcatheter, and typically consists of an inner liner, an intermediate reinforcement layer, an outer polymer layer, and a surface coating.
The liner material is usually a lubricious material (e.g., etched PTFE Liner ) to ensure a smooth lumen; the intermediate reinforcement layer is usually woven or wound with metal wire to increase the strength and pushing force of the catheter. The design of the middle reinforcement layer represents the important properties of the microcatheter for different vascular lesions, e.g.,
The micro catheter the braid + wrap design allows for good proximal braid pushability and good distal wrap flexibility, which is a very good choice for neurovascular delivery, while for CTO lesions, the high stiffness of the braid can help them traverse calcification. In addition, the distal surface of the tubing is usually coated with a certain length of coating material (usually hydrophilic) to enhance the passage of the microcatheter through the vessels and lesions.