the catheter according to the invention consists of a tubular body 1 which is connected on the one side to the interior space of a balloon - shaped body 2 and on the other side to a pump unit 3 . to this end the rear end 4 of the tube 1 is arranged airtightly in a branch piece 5 that has three branches . the one branch 6 is connected to the pump unit 3 . the second branch 12 connects onto a second tubular body arranged in the tubular body , which second tubular body extends beyond the balloon 2 and serves for the passage of a flexible guide wire , which is pre - arranged in the passages in the human body , for example the blood vessel . the tubular bodies of the catheter are finally carried along this guiding . the manner of operation of the catheter is assumed to be known and consequently falls outside the scope of the invention . if the balloon is brought to the location to be treated in the artery a 1 , see fig2 the balloon can be inflated via the tube 1 to an operational diameter d by the medium in the pump unit 3 . in the case that there is a narrowing of the artery a 1 , the inner diameter of which coincides with the outer diameter of the balloon d , this narrowing can be pressed out . this so - called angioplasty method is also assumed to be known and will not be further described . the diameter d of the balloon 2 is always of the same size irrespective of the pressure in the balloon 2 , which is realized by the use of non - stretch material in the peripheral direction of the cylinder wall . in the embodiment according to fig2 and 3 , the balloon 2 is formed with a fold 7 , which is achieved by fixing to one another at fixing points 8 two describing lines running on a parallel axis . these fixing points can be of any random shape and length as long as care is taken that the outer periphery of the cylinder 2 is virtually circular . the fixing welds 8 can be detached by raising the pressure , as a result of which the attachment between the two describing lines of the cylinder wall is released , and the balloon can be further inflated to the position as in fig3 . in this position the balloon has a diameter d and is suitable for a larger artery a 2 . it will be apparent from the above that the surgeon will first have to treat the small artery a 1 and then the larger artery a 2 . the surgeon does not therefore need to completely withdraw the catheter from the blood vessel as is usual with existing catheters . fig4 shows an embodiment , in which the cylindrical wall of the balloon 2 is taken in to form a fold 7 , which is realized by arranging a tear - off strip 9 over the balloon . this tear - off strip is provided at line 10 with weakened points , which tear loose when the pressure in the balloon 2 is increased . the fold 7 can be filled with a substance 11 , for example paste , which has a therapeutic or medicinal effect . this substance is released against the inner wall of the blood vessel as soon as the tear - off strip 9 is torn loose . for the sake of completeness it is mentioned that the strip 9 is extended over the head end sides of the balloon in order to seal the ends of the fold . fig5 shows an embodiment in which the balloon 2 displays three folds 7 whereby the weakened areas 8 on each fold 7 have a different release moment , depending on the pressure prevailing in the balloon 2 . in this way the balloon can be brought to four different diameters . it is noted that in fig5 the balloon in inflated state can be stepped in diameter over its length whereby the portions of greater diameter can be provided with the folds 7 . in this way a portion 12 can also be applied with a very small diameter , which allows no fold forming . fig6 shows an embodiment , in which the tear - off strip 9 is arranged in the balloon such that the fold 7 is connected to the coaxial inner tube by means of a tear - off strip 9 &# 39 ; and / or 9 &# 34 ;. weakened points on the line 10 ensure that when the pressure is raised the strip 9 tears along the line 10 , after which the balloon can be further inflated to the larger diameter d . fig7 shows an embodiment in which a middle portion of a continuous balloon is narrowed by means of the fold ( s ) 7 , here extending in an axial way . the smaller middle section is intended to be located where an accurate position is necessary . for instance , for some heart diseases a valve should be dilated . however , positioning is very difficult due to the high blood velocity therethrough . owing to the diminished diameter the middle portion can be accurately positioned by fitting it in the narrowed opening in the valve . afterwards , by raising the pressure in the balloon , the middle portion is brought to the larger diameter of the balloon , so being able to dilate the valve tissue .
a balloon catheter for the widening of passages in the body , such as blood vessels , comprises a tubular body connected at one side to the interior of a cylindrical balloon and at another side to a pump unit . the balloon can be enlarged from a first predetermined diameter to a second predetermined diameter without completely withdrawing the catheter from the body passages .