Heating/sensing catheter apparatus for minimally invasive applications

Abstract

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.

Description

RELATED APPLICATION[0001]This application claims the benefit of provisional application No. 61 / 635,348, filed Apr. 19, 2012, the contents of which are hereby incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]This invention relates to medical catheter apparatus for minimally invasive applications. It relates especially to catheter apparatus which utilizes electromagnetic radiation to simultaneously controllably heat, and detect the temperature of, fluid or tissue in a human or animal body. The apparatus includes an antenna catheter which is essentially a long flexible cable having a distal end or probe containing an antenna. In order to perform its function, the catheter must be small in diameter and flexible so that it can be threaded along blood vessels and other natural passages in the body to position the antenna at a selected target site.[0004]By placing the catheter probe at the region of interest in the body, one may warm blood an...

AI Technical Summary

Benefits of technology

[0022]To enable the catheter to heat (transmit) and detect temperature (radiometrically sense) simultaneously, a passive diplexer is provided at the proximal end is of the cable, the cable and diplexer forming a unique assembly which also allows for cooling of the cable. That is, to minimize component insertion loss, the cable/diplexer assembly provides a reduced cable impedance as well as a fluid path for a coolant delivered from the control unit to the catheter.

[0023]Even when the catheter is to be introduced into larger body passages and thus may include an internal diplexer and radiometer as described in the above patent, it is desirable that the catheter apparatus include this special cable to prevent excessive heating of the cable by the transmitter.

[0024]As will be described in more detail later, the cable has a hollow center conductor and a relatively low cable impedance, e.g. 30 ohms, compared to the u

Problems solved by technology

However, that solution rigidifies the catheter probe and places a lower limit on its diameter making it more difficult to th

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