Method of controlling the temperature of gasses passing through a Joule-Thomson orifice
The present invention relates to apparatus, systems, and methods utilizing cryogenic cooling in an angioplasty balloon catheter for treatment of arterial stenosis and prevention of restenosis. More particularly, the present invention relates to an angioplasty balloon catheter utilizing expansion of compressed gas to effect Joule-Thomson cooling of an angioplasty balloon, and optionally further incorporating external temperature sensors utilizable to identify a locus for treatment of arterial stenosis. The present invention further relates to angioplasty treatment systems incorporating such a catheter, and to cryogenic angioplasty methods for treating arterial stenosis and discouraging restenosis.
1. A method of controlling temperature of gasses passing through a Joule-Thomson orifice, comprising:
a) supplying to said Joule-Thomson orifice a gas mixture comprising a pressurized cooling gas and a pressurized heating gas in selected proportion;
b) controlling temperature of gasses passing through said Joule-Thomson orifice by:
i) decreasing temperature of gasses passing through said Joule-Thomson orifice by proportionally increasing a ratio of cooling gas to heating gas in said gas mixture; and/or
ii) increasing temperature of gasses passing through said Joule-Thomson orifice by proportionally decreasing a ratio of cooling gas to heating gas in said gas mixture.
2. The method of claim 1 further comprising pre-mixing said gas mixture, utilizing pressurized heating gas and pressurized cooling gas in a selected proportion.
3. The method of claim 1 , further comprising utilizing an automated control unit to select a ratio of cooling gas to heating gas in said gas mixture by
d) receiving temperature data from a thermal sensor in a vicinity of said Joule-Thomson orifice; and
e) sending control signals to at least one remotely controllable gas flow valve in response to an algorithmic evaluation of said received temperature data,
thereby modifying said selected ratio of cooling gas to heating gas in said gas mixture.