in fig1 and 2 , a catheter 10 is provided with an inner tube 11 . the leading end portion , as located at the lefthand end portion of fig1 of the inner tube 11 , is suitably bent into a desired shape according to the related part ( e . g ., a blood vessel part to be inspected or treated ) of a patient . on this inner tube 11 , there is fitted an outer tube 12 which is formed in a cylindrical shape so as to move freely in the axial directions . as will be described hereinafter , the inner tube 11 can turn integrally with the outer tube 12 . this outer tube 12 is equipped at its base end portion , as located at the righthand end portion of fig1 with a grip member 21 to allow easy gripping of the catheter 10 . as clearly seen , especially from fig2 the outer tube 12 has a round section , but a guide hole 13 extending axially through the outer tube 12 has a rectangular or square section . thus , the inner tube 11 has a rectangular or square section dimensioned to leave a clearance 15 between the inner periphery of the guide hole 13 of the outer tube 12 and the outer periphery of the inner tube 11 which allows the inner tube to move axially through the guide hole 13 . by thus shaping the section of the inner tube 11 and the guide hole 13 of the outer tube 12 , the inner tube 11 and the outer tube 12 are turned together when either of them is turned . therefore , it is necessary to maintain the accuracy of the clearance 15 to warrant a smooth movement of the inner tube 11 along the guide hole 13 . this accuracy of clearance is far better than when the inner tube 11 is enabled to turn without any friction within the guide hole 13 . the base end portion , as located on the righthand end portion of fig1 of the inner tube 11 is adapted to be connected through a connector 90 to another tube 16 . this tube 16 is jointed to a syringe ( not shown ) so that a contrast medium , for example , is fed into an inner passage 17 extending axially in the inner tube 11 . as shown in fig3 the catheter 10 is inserted into the body by a well - known method , and the inner tube 11 is then moved axially and turned so that the leading end portion of the inner tube 11 can be brought to a position near the part 18 to be inspected . at this position , the contrast medium , as having passed through the inner passage 17 , is fed from the leading end portion of the inner tube 11 to the part 18 . on the base end portion of the inner tube 11 , there is engraved or indicated a scale 19 which allows an easy determination as to how far the outer tube 12 has moved on the inner tube 11 . at the leading end portion of the inner tube 11 , on the other hand , there is mounted a soft tip 14 . this soft tip 14 softens as much as possible any impact when the leading end portion of the inner tube 11 comes into abutment against a blood vessel wall during the use of the catheter 10 . if the external diameter of the soft tip 14 is suitably adjusted , the outer tube 12 comes , when moved leftward , into engagement at its leading end portion ( or its lefthand end portion ) with the leading end portion of the inner tube 11 so that its further movement in the leftward direction is prevented . as a result , the movement of the outer tube 12 is confined between the connector 90 and the soft tip 14 so that the outer tube 12 is prevented from coming off the inner tube 11 . the inner tube 11 and the outer tube 12 may be identical in their materials and internal structures to those of the prior art . specifically , the material can be exemplified by polyamide , polyurethane or polyethylene , or a mixture of the recited polymers as the case may be , such as when a higher bending strength or hardness is demanded . on the other hand , the internal structure may be exemplified by a single - layered tube or a two - or more - layered tube . in the latter case , a mesh of stainless steel or another metal may be sandwiched between the two adjoining layers . in order to observe the catheter clearly in an x - ray examination , the inner tube 11 ( or the outer tube 12 , as the case may be ) may contain a material such as an x - ray impermeable substance such as barium . in the catheter 10 thus far described , both the sectional shape of the guide hole 13 extending axially through the outer tube 12 and the sectional shape of the inner tube 11 are rectangular or square throughout the entire length to facilitate axial movement along the guide hole 13 . this structure is adopted because both tubes are turned simultaneously or integrally when either of them is turned . the invention should not be limited to this structure , but may adopt another structure as long as the simultaneous or integral turns of the tubes are ensured . as shown in fig4 to 6 , both the sectional shape of the guide hole 13 extending axially through the outer tube 12 and the sectional shape of the inner tube 11 , to facilitate axial movement along the guide hole 13 , are made partially rectangular or square . in the remaining portions , however , both the sectional shape of the guide hole 13 extending axially through the outer tube 12 and the sectional shape of the inner tube 11 may be made circular to move axially along the guide hole 13 . in this case , the sectional shape of the lefthand side of the outer tube 12 is also circular . on the outer circumference of the inner tube 11 having a round sectional shape , as shown in fig7 and 8 , there is fixed a member 20 having keys 20 a or an oval member 30 as shown in fig9 . the sectional shape of the guide hole 13 extending axially through the outer tube 12 is formed into a shape similar to that of the member 20 or the member 30 so that the inner tube 11 and the outer tube 12 can be turned simultaneously or integrally . in the device shown in fig7 a grip member 21 is fixed on the inner tube 11 . in a bracket 40 arranged outside of the outer tube 12 , as shown in fig1 to 12 , there are formed a pair of slits 41 extending axially . a member 42 is comprised of two concentric rings connected by two radial ribs which are guided in the slits 41 . the inner ring is connected to the outer side of the outer tube 12 . moreover , the bracket 40 is integrally connected at its righthand end portion with the connector 90 . by adopting this structure , by operating only the member 42 , the outer tube 12 and the inner tube 11 can be turned integrally and the outer tube 12 can be moved axially . the shape of the slit 40 should not be limited to the shown straight one but may be helical or stepped . on the outer tube 12 , as shown in fig1 , there are integrally formed a pair of projections 51 . on the outer tube 12 , there is also a ring member 52 which is made axially movable relative to the tube 12 . when the ring member 52 moves axially toward the projections 51 and rides on them , as shown in fig1 , the outer tube 12 is radially reduced to clamp onto the inner tube 11 . thus , the inner tube 11 is locked by a lock mechanism 53 which is composed of the ring member 52 and the paired projections 51 , so that the outer tube 12 can be fixed at an arbitrary position . the lock mechanism for fixing the outer tube 12 at an arbitrary position relative to the inner tube 11 may be exemplified by a tube 55 which is made of an elastic material and has an expansion slot 54 , as shown in fig1 and 16 . a second example of the lock mechanism 53 is shown in fig1 . in the structure shown in fig1 to 12 , a pair of wedges 56 , formed on the opposite sides of the member 42 , are fitted in the slits 41 . a third example of the lock mechanism 53 is shown in fig1 and 19 . in the structure shown in fig1 to 12 , the wedges 56 , as formed integrally with a moving member 50 , are fitted axially in the inner circumference of the member 55 which is fixed on the bracket 40 . a fourth example of the lock mechanism 53 is shown in fig2 . in the structure shown in fig1 to 12 , a cylindrical portion 43 having an expansion slot 42 a is made integrally with the member 42 . a nut member 60 fitted on the cylindrical portion 43 is fastened on a threaded portion 61 of the cylindrical portion 43 . the cylindrical portion is radially reduced , as shown in fig2 as a result of a camming action by the nut member 60 , to grip the tube 12 to prevent the member 42 from moving on the bracket 40 . as a result , the outer inner tube 12 is locked . the bracket 40 shown in fig1 to 12 , is shown in fig2 and is provided with an elastic joint 70 which is interposed between the bracket 40 and the outer tube 12 to prevent the catheter 10 from being damaged when bent . while the preferred embodiments have been described , variations thereto will occur to those skilled in the art within the scope of the present inventive concepts which are delineated by the following claims .
a catheter has an outer tube capable of turning an inner tube smoothly . the catheter comprises an inner tube 11 having a leading end portion formed into a suitable shape matching an affected part 18 , an outer tube 12 fitted movably on the inner tube 11 and a joint mechanism for enabling the inner tube 11 to move integrally with the outer tube 12 without preventing the movement of the outer tube 12 .