The balloon 6 can be contracted easily by aspiration of the fluid in the balloon without much changing the profile of the balloon 6, and can easily pass through the narrowed portion, and when the cooling liquid is injected into the balloon 6, together with the expansion of the balloon 6 A high frequency balloon catheter system for cooling and expanding a narrowed portion while cooling the balloon (6) by releasing the cooling liquid to the outside, is provided. A catheter shaft (1) is constituted by an inner cylinder shaft (3) and an outer cylinder shaft (2) slidable relative to each other, and a distal end portion (5) of the inner tube shaft (3) A front neck 6A of the balloon 6 covers the inner tube shaft 3 and comes close to each other and is provided with a check valve (not shown) 8) are formed. That is, when the inner liquid of the balloon (6) is aspirated to have a negative pressure, the check valve (8) is closed and the balloon (6) contracts. When the inner liquid is injected and positive pressure is taken, together with expansion of the balloon The check valve (8) opens to release the internal liquid to the outside. A high-frequency power supply electrode (11) is installed in the balloon (6), and the high frequency power supply electrode (11) is connected to the high frequency generator (41) through a current supply line (42) in the catheter shaft (1) , And an infusion pump (29) for feeding cooling water (C) is connected to a liquid feed path (9) which always communicates with the inside of the balloon (6).バルーン(6)のプロファイルをあまり変えずに、バルーン内液の吸引により収縮が自在となり、狭窄部も容易に通過でき、バルーン(6)内に冷却液を注入すると、バルーン(6)の拡張とともに冷却液は外部に放出されてバルーン(6)を冷却し、内膜を保護しながら狭窄部を加熱拡張する高周波バルーンカテーテルシステムを提供する。 互いにスライド可能な内筒シャフト(3)と外筒シャフト(2)とでカテーテルシャフト(1)が構成され、内筒シャフト(3)の先端部(5)と外筒シャフト(2)の先端部(4)との間には、収縮拡張可能な弾性バルーン(6)が設置され、バルーン(6)の前方ネック(6A)は内筒シャフト(3)に被さって互いに近接して逆止弁(8)を形成している。すなわちバルーン(6)の内液を吸引し陰圧とすると、逆止弁(8)は閉じてバルーン(6)は収縮し、内液を注入し陽圧とすると、バルーン(6)の拡張とともに逆止弁(8)は開いて外部に内液を放出する。また、バルーン(6)内には高周波通電用電極(11)が設置され、この高周波通電用電極(11)は、
