HEATING/SENSING CATHETER APPARATUS FOR MINIMALLY INVASIVE APPLICATION
Catheter apparatus comprises a coaxial cable having proximal and distal ends. The cable includes a hollow center conductor, an outer conductor and an electrically insulating layer between the conductors. An antenna is at the distal end of the cable, and a diplexer is connected to the cable, the diplexer including a transmit path for connecting the antenna to a transmitter which transmits first frequency signals and a receive path for connecting the antenna to a receiver which detects second frequency signals the diplexer isolating the signals on the two paths from one another. A transmission line connects the cable to the diplexer, the transmission line having a segment with a tubular inner conductor one end of which is connected to the center conductor and a second end of which is adapted for connection to a coolant source, the center and inner conductors forming a continuous coolant pathway.
1 . Catheter apparatus comprising
an elongated flexible coaxial cable having proximal and distal ends, said cable including a hollow center conductor, an outer conductor and an electrically insulating layer in an annular space between said conductors;
an antenna at the distal end of the cable;
a diplexer including a transmit path for connecting the antenna to a transmitter which transmits signals of a first frequency and a receive path for connecting the antenna to a receiver which detects signals of a second frequency, said diplexer isolating the signals on the two paths from one another;
a transmission line connecting the cable to the diplexer, said transmission line including a segment with a tubular inner conductor one end of which is connected to the center conductor of the cable and a second end of which is adapted for connection to a coolant source, said center conductor and said inner conductor forming a continuous coolant pathway.
2 . The apparatus defined in claim 1 wherein said receive path includes a first electrical filter.
3 . The apparatus defined in claim 1 and further including an impedance-matching transformer in series with the cable and the transmission line.
4 . The apparatus defined in claim 1 wherein the cable outer conductor comprises braided conductive strands.
5 . The apparatus defined in claim 1 wherein the cable insulating layer comprises a flexible winding of one or more dielectric strands having multiple fluid flow paths therebetween.
6 . The apparatus defined in claim 1 wherein said antenna comprises an extension of the center conductor beyond the outer conductor and the insulating layer.
7 . The apparatus defined in claim 6 wherein said extension is tubular and continues said fluid pathway to the outside.
8 . The apparatus defined in claim 1 wherein said antenna is connected to the center conductor via a connection device at the distal end of the cable.
9 . The apparatus defined in claim 8 wherein the connection device defines a fluid path between the interior of the center conductor and the outside.
10 . The apparatus defined in claim 1 wherein the antenna is flexible.
11 . The apparatus defined in claim 1 and further including a stand-off device adjacent to the distal end of the cable for centering said antenna in a body passage.
12 . The apparatus defined in claim 1 and further including one or more temperature detectors positioned in said fluid pathway for monitoring coolant temperature at one or more locations therealong.
13 . The apparatus defined in claim 1 and further including a microwave or RF transmitter connected to said transmit path.
14 . The apparatus defined in claim 1 and further including a coolant source connected to said second end of the tubular inner conductor of said transmission line segment.
15 . The apparatus defined in claim 1 wherein said cable and said diplexer are formed as a unitary disposable first part designed for connection both electrically and mechanically to a mating reusable second part containing microwave receiver.