Catheters in vascular interventional radiology: an illustrated review

T he catheter is an invaluable tool for interventional radiologists.In 1929, Dr. Werner Forssmann demonstrated the catheterization of the pulmonary artery with a simple rubber catheter by performing an angiogram through the ante-cubital vein. 1 Today, a variety of catheters are available in the armamentarium of the interventional radiologist to suit different needs.However, the literature lacks a comprehensive compilation of the properties, types, and uses of catheters.In this review, we aim to describe the characteristics, properties, and uses of the common angiographic catheters used in vascular interventions. Properties of cathetersA catheter is a flexible hollow tube that can be inserted into a duct, body cavity, or vessel.It consists of a hub at the rear end and a distal tubular shaft.The shaft can be straight or molded into different curved shapes (primary, secondary, or tertiary curves) and can have a tapered or non-tapered tip (Figure 1).Catheterization is the process of inserting a catheter.Angiographic catheters are the most important tool in any vascular intervention.They are introduced through a sheath placed at the vascular access site.Wires introduced via these catheters are navigated to enter the target vessels.Once the catheters are inside the vessel, they can be used to conduct diagnostic angiography of the intended vascular territory and as a conduit for the delivery of balloons and stents for endovascular intervention at the intended location.An ideal catheter should have strength, good torque control, radiopacity, flexibility, an atraumatic tip, and low surface friction for good trackability over a guidewire.2 Construction i) Surface coating: surface coatings can modify the catheter's friction coefficient, thrombogenicity, or antimicrobial properties.ii) Outer layer: angiographic catheters can be made of polyethylene, polyurethane, nylon, polytetrafluoroethylene, silicone, polyvinyl chloride, or a combination of these materials.Their respective properties, advantages, and disadvantages are discussed in Table 1.3,4 The coefficient of friction on the luminal side is important for easy passage of the wire and achieving high flow rates of contrast during angiography.Conversely, a low coefficient of friction on the catheter's outer surface helps its trackability,