Single integrated structural unit for catheter incorporating a microwave antenna

Abstract

The catheter constitutes a single integrated structural unit comprising a first tubular balloon-supporting structure having a given outer diameter and a second structure inserted therein comprising an antenna and a coaxial cable for energizing the antenna. This permits both the antenna and the longitudinal cable to be wider, without any increase in the given outer diameter, than would be the case if the catheter were a prior-art non-integrated structure in which the tubular first structure and the second structure are separate detached units and, therefore, require clearance therebetween to permit insertion. In both basic and preferred embodiments, the single integrated structural is achieved by an electrically conductive shield attached by spacers to an outer conductor of the coaxial cable. In the basic embodiment, the shield is spaced from both the outer cable conductor and first structure to form inner and outer channels for exiting and entering the circulating balloon-inflating liquid. In the preferred embodiment, the shield is bonded to the inner surface of the first structure to form the entering channel, while the exiting channel is formed by the interior of a tubular inner cable conductor which may also house a thin tube for air inflating a Foley balloon. The inner channels of both embodiments include a ¼ wavelength choke structure at the distal end of the coaxial cable. A modification divides the circumference of the channels into separate angular sectors for independently circulating inflating liquid to any of a plural number of differently-sized balloons.