A Cryogenic Catheter for Treating Heart Arrhythmia
E D. Marquardt, Ray Radebaugh, J Dobak
Progress in the development of a cryogenic catheter to treat heart arrhythmia is discussed. This system uses a mixed-gas Joule-Thomson refrigerator to cool the tip of a catheter that cen be indserted into the body through the large ceins leading into the heart. The cryogenic catheter is intended to treat heart arrhythmia characterized by an abnomally rapid heart rate, although the system has a wide variety of other medical applications. Approximately 2 million people in the U.S. suffer from rapid-rate heart arrhythmia. Catheter therapy has proven to be a more effective and less expensive method of treatment than alternatives such as drugs or surgery. A cryogenic catheter has significant advantages over existing catheters use in this form of therapy. The catheter has coaxial tubes for the high and low pressure streams with a minature heat exchanger and J-T orifice at the catheter tip. The high pressure is maintained at 2.5 Mps. The largest diameter is 3 mm, the length is 90 cm, and all but the last 10 mm to 20 mm is flexible. The gas mixture has been optimized for the required operating conditions using non-flammable and low ozone depletion gases. Low cost techniques have been incorporated into the fabrication of the cold tip so exposed to ambient air. Using room themperature gelatin to simulate tissue hear loads, catheter tip temperatures of 160 to 175 K have been achieved and ice balls about 26mm in diameter weighing 11 G were created. We estimate that ice balls about 10 mm in diameter weighing 1.5 to 2.0 g are required to treat ventricular arrhythmia. Althogether the heat load in out experiments was less than the in vivo load, we believe the current refrigeration power is sufficent to meet the clinical requirement.
, Radebaugh, R.
and Dobak, J.
A Cryogenic Catheter for Treating Heart Arrhythmia, Advances in Cryogenic Engineering, Cryogenic Engineering Conference | | | Plenum Press
(Accessed February 25, 2024)