The design of metallic tip catheters.

Abstract

Opacification of the aortic arch and, in particular, coronary arteriography have been carried out with various catheter designs (1, 2, 4, 7). Metallic tips have been used before but never described in detail (3, 5, 6). The development and plan of a new metallic catheter tip which permits the design and fabrication of catheters for differential opacification of the aortic arch comprises the basis for this report. Catheter: A metallic tip (Fig. 1, A and B) is swaged to fit the end of a suitable piece of radiolucent polyethylene tubing. The design of this tip permits rapid construction of specific catheters when needed and it may be re-used. The metallic catheter tip has a smooth-bore polished surface. Two designs are available—one with an end opening and side holes and the other with a closed end and side holes. Opaque guides (lead or stainless steel shots inserted into the distal tips) for polyethylene catheters of any size may also be used. These are heat-sealed in the ends of the catheter and can readily serve as markers. Discussion: The metallic tip, when swaged to the end of a suitable polyethylene tubing, has produced catheters which could be localized with ease under fluoroscopic guidance. The design of the tip with its smooth-bore rounded surface provides for easy insertion into the arterial or venous channel. Catheters of this design can be utilized for retrograde introduction into the arterial system without flexible wire guides. The additional weight of the metallic tip aids in manipulation of the catheter with changes in the position of the animal. In addition, the tip obviates the need for injecting opaque material for localization of the catheter (Fig. 2, A). When the tip with a closed end and side holes is used, a spray-like effect of the medium is obtained. This can easily opacify the large volume of the supravalvular segment of the aortic arch (Fig. 2, B). The metallic tip also makes possible radiological localization of the catheter in specific regions of the vascular system for appropriate pressure recordings (Fig. 2, C). Summary: The design of a new metallic catheter tip is described and illustrated. The advantages of this metallic tip over other commonly used types in regard to ease of guidance and location are discussed. A tip of one design yields a spray-like effect of the opaque medium which renders opacification of large volumes, such as the supravalvular segment of the aorta, a standard procedure. The use of polyethyiene tubing with the metallic tip provides a substantial reduction of cost in the fabrication of the catheters.