Source: https://patents.justia.com/patent/7112198
Timestamp: 2019-11-22 08:22:32
Document Index: 648176855

Matched Legal Cases: ['art 3', 'art 3', 'art 3', 'art 3', 'art 3', 'art 3']

US Patent for Radio-frequency heating balloon catheter Patent (Patent # 7,112,198 issued September 26, 2006) - Justia Patents Search
Justia Patents ApplicatorsUS Patent for Radio-frequency heating balloon catheter Patent (Patent # 7,112,198)
Radio-frequency heating balloon catheter
A radio-frequency heating balloon catheter is capable of cauterizing a target lesion in an atrial vestibule. The radio-frequency heating balloon catheter has a catheter tube including an outer tube and an inner tube slidably extended through the outer tube. An inflatable balloon is connected to an extremity of the outer tube and a part near an extremity of the inner tube, and is capable of coming into contact with a target lesion when inflated. A radio-frequency electrode serves as a counter to a surface electrode attached to a surface of a subject's body and is placed in a wall of the balloon or inside the balloon to supply radio-frequency power between the surface electrode and the radio-frequency electrode. A temperature sensor senses temperature inside the balloon, a guide shaft projects from the extremity of the inner tube and is capable of holding the balloon on the target lesion, and a guide wire extends through the catheter tube and the guide shaft.
Accordingly, it is an object of the present invention to provide a radio-frequency heating balloon catheter capable of making the individual cauterization of the edges of the four pulmonary vein openings unnecessary and of capable of cauterizing a wide range of the atrial vestibule where the pulmonary veins join together with a balloon kept in a coaxial state.
The basic construction of a radio-frequency heating balloon catheter 1 in a first embodiment according to the present invention will be described with reference to FIG. 1. The radio-frequency heating balloon catheter 1 will be described as applied to the treatment of a lesion in the left atrial vestibule 103. Naturally, the radio-frequency heating balloon catheter 1 is applicable to the treatment of a lesion in the right atrial vestibule.
Referring to FIG. 1, the radio-frequency heating balloon catheter 1 comprises a catheter tube 4 including an outer tube 2 and an inner tube 3 slidable relative to the outer tube 2, an inflatable balloon 6 of a shape capable of coming into contact with a target lesion 100 in the left atrial vestibule 103 when inflated, a radio-frequency electrode 8 disposed inside the balloon 6, a lead wire 10 electrically connected to the radio-frequency electrode 8, a thermocouple 12 placed in the balloon 6 to sense temperature in the balloon 6, a guide shaft 5 extending from a front end part 3a of the inner tube 3 and capable of holding the balloon 6 on the target lesion 100, and a guide wire 16 extended through the catheter tube 4 and the guide shaft 5 to guide the catheter tube 4 and the guide shaft 5 to the target lesion 100.
As shown in FIG. 2, the guide shaft 5 has a length such that the side surface 5a of the guide shaft 5 is able to be in contact with the inner surface of the wall of the left superior pulmonary vein 101 or the left inferior pulmonary vein 102 with the inflated balloon 6 in contact with the opening of the left atrial vestibule 103. The guide shaft 5 has a length longer than that of the balloon 6. For example, the length of the guide shaft 5 is between 2 and 10 cm.
The front end part 3a of the inner tube 3, or the guide shaft 5 is provided with side holes 7 through which pulmonary venous blood is sucked. The side holes 7 are used also for discharging physiological saline water into the left superior pulmonary vein 101.
As shown in FIG. 5, the lead wire 10 is wound helically. One end of the lead wire 10 is electrically connected to a radio-frequency power generator 40. Radio-frequency power generated by the radio-frequency power generator 40 is supplied through the lead wire 10 to the radio-frequency electrode 8. The balloon 6 has a large diameter to cauterize a target lesion 100 in the left atrial vestibule 103 having the opening greater than those of the pulmonary veins 101 and 102. Therefore, the radio-frequency power generator 40 needs to generate high radio-frequency power to heat the target lesion 100 at a desired temperature. For example, when the radio-frequency power of 13.56 MHz generated by the radio-frequency power generator 40 is supplied between the radio-frequency electrode 8 and a counter electrode 53 attached to the surface of the subject's body, and the diameter of the balloon 6 is about 2.5 cm, the radio-frequency power is in the range of 200 to 400 W. When the radio-frequency power is supplied between the radio-frequency electrode 8 and the counter electrode 53, tissues 18 in contact with the balloon 6 are cauterized by capacitive heating accompanied by radio-frequency dielectric heating. Pulmonary venous blood is sucked through the side holes 7 formed in the front end part 3a of the inner tube 3 or the guide shaft 5, and physiological saline water is discharged through the side holes 7 to cool the radio-frequency electrode 8 wound round the inner tube 3. Thus, temperature distribution inside the balloon 6 is made uniform. Consequently, the target lesion 100 in contact with the balloon 6 can uniformly be heated for cauterization.
The radio-frequency heating balloon catheter 1 in the first embodiment is provided with the guide shaft 5 extending from the front end part 3a of the inner tube 3, and the balloon 6 can be held on the target lesion 100 by placing the side surface 5a of the guide shaft 5 in contact with the inner surface of the wall of, for example, the left superior pulmonary vein 101. Thus, the inner surface of the wall of the left superior pulmonary vein 101 is never cauterized even if high radio-frequency power is supplied to cauterize the target lesion 100 in the left atrial vestibule 103, while it is possible that the inner surface of the wall of the left superior pulmonary vein 101 is cauterized when the balloon 6 is held on the target lesion 100 only by the guide wire 16. Thus, the target lesion 100 in the left atrial vestibule 103 can safely be cauterized with the balloon 6 held in a coaxial state.
The radio-frequency electrode 8 wound round the inner tube 3 can be cooled by sucking pulmonary venous blood through the side holes 7 formed in the front end part 3a of the inner tube 3 or the guide shaft 5, and discharging physiological saline water through the side holes 7. Temperature distribution in the balloon 6 can be made uniform by stirring the liquid contained in the balloon 6 by a stirring mechanism 14, which will be described later. Thus, the target lesion 100 of a diameter in the range of, for example, 3 to 5 cm in contact with the balloon 6 can uniformly be cauterized.
Referring to FIGS. 3 and 4, in which the right end B of a view shown in FIG. 4 is joined to the left end A of a view shown in FIG. 3, the radio-frequency heating balloon catheter 1 comprises a catheter tube 4 including an outer tube 2 and an inner tube 3 slidable relative to the outer tube 2, an inflatable balloon 6 connected to the extremity of the outer tube 2 and a part near the extremity of the inner tube 3, and capable of coming into contact with a target lesion 100 when inflated, a radio-frequency electrode 8 disposed inside the balloon 6, a lead wire 10 electrically connected to the radio-frequency electrode 8, a thermocouple 12 placed in the balloon 6 to sense temperature in the balloon 6, a guide shaft 5 extending from a front end part 3a of the inner tube 3 and capable of holding the balloon 6 on the target lesion 100, a guide wire 16 extended through the catheter tube 4 and the guide shaft 5 to guide the catheter tube 4 and the guide shaft 5 to the target lesion 100, and a stirring mechanism 14 to make uniform the temperature distribution in the liquid contained in the balloon 6.
The radio-frequency electrode 8 consists of a plurality of parallel splines 8a extended between the front sleeve 20 and the back sleeve 21. The straight splines 8a can be curved along the inner surface of the balloon 6 as shown in FIG. 3 when the inner tube 3 is slid relative to the outer tube 2 to inflate the balloon 6.
The radio-frequency electrode 8 consists of the several to several tens straight splines 8a extended between the front sleeve 20 and the back sleeve 21. The straight splines 8a can be curved by sliding the outer tube 2 and the inner tube 3 relative to each other to decrease the distance between the front sleeve 20 and the back sleeve 21 to form the radio-frequency electrode 8 in the shape of a basket or an onion. The change of the straight splines 8a between a straight shape and a curved shape can be ensured by forming the straight splines 8a of a shape memory alloy.
Front and left end parts of the splines 8a are coated with a resin to prevent the excessive radio-frequency heating of the front and the back end parts of the splines 8a.
Capacitive type radio-frequency heat can be generated between the radio-frequency electrode 8 and a counter electrode 53 (FIG. 5) attached to the surface of a subject's body when the radio-frequency power generator 40 generates radio-frequency power of, for example, 13.56 MHz.
The output rotating speed of the motor 38 is reduced by the reduction gear 35 and the lowered output rotating speed of the reduction gear 35 is transmitted through the driven gear 26 to the base sleeve 23. The rotation of the base sleeve 23 is transmitted to the back sleeve 21 by the lead wire 10 to turn the splines 8a in the balloon 6. The liquid filling up the balloon 6 is stirred by the turning splines 8a, so that irregular temperature distribution in the balloon 6 due to heat transfer by convection can be prevented and temperature is distributed uniformly in the balloon 6. The temperature of the liquid in a central part of the balloon 6, that of the liquid around the wall of the balloon 6 and that of tissues 18 in contact with the balloon 6 can be made substantially equal by thus stirring the liquid contained in the balloon 6. The temperature of the liquid in the central part of the balloon 6 is measured and is indicated by the thermometer 42, and the temperature indicated by the thermometer 42 can be considered to be the accurate temperature of the target lesion 100 in contact with the balloon 6.
To insert the balloon catheter 1 in the left atrial vestibule 103, the balloon 6 is deflated and the inner tube 3 is slid to a limit position. Since the distance between the front sleeve 20 and the back sleeve 21 increases when the balloon catheter 1 is thus inserted in the left atrial vestibule 103, the splines 8a are extended straight and the balloon 6 is deflated in the smallest diameter. The thus deflated balloon 6 is inserted in the left atrial vestibule 103. The position of the balloon catheter 1 is adjusted to locate the balloon 6 near the target lesion 100, a contrast medium and physiological saline water are injected through the branch tube 51 into the balloon 6, and the inner tube 3 is pulled to inflate the balloon 6. Consequently, the distance between the front sleeve 20 and the back sleeve 21 decreases, and the splines 8a are curved to form a basket-shaped radio-frequency electrode 8 in the balloon 6. The fine adjustment of the position of the balloon catheter 1 is performed to bring the balloon 6 into contact with the target lesion 100.
Although there is the possibility that the liquid around the sleeves 20 and 21 on which the splines 8a converge is heated excessively, such excessive heating of the liquid can be prevented by forming the sleeves 20 and 21 of a material having a low dielectric constant, such as a resin or a ceramic material, by coating pats of the splines 8a with a resin or by circulating cooling water through the inner tube 3.
20020165535 November 7, 2002 Lesh et al.
1297795 April 2003 EP
96/15741 May 1996 WO
02/19934 March 2002 WO
2004/017850 March 2004 WO
Patent number: 7112198
Patent Publication Number: 20040172110
Application Number: 10/747,301