Torquable Catheter and Method

In the past, steerable catheters have heretofore been provided to facilitate maneuvering in blood vessels. However, in the past with such devices it has been difficult to achieve a substantially one to one rate of movement for the proximal and distal extremities of the catheter. There is therefore a need for a new and improved catheter which can achieve such a one-to-one ratio and a method for making the same.

In general, it is an object of the present invention to provide a torquable catheter and method in which a substantially one to one ratio of movement between proximal and distal extremities of the catheter can be achieved.

Another object of the invention is to provide a catheter and method of the above character which has the desired degree of flexibility.

Another object of the invention is to provide a catheter and method of the above character which can be utilized in a blood vessel.

Another object of the invention is to provide a catheter and method of the above character in which the distal extremity can be steered.

Another object of the present invention is to provide a catheter and method of the above character which is particularly adapted for use in mapping and/or ablation procedures in the heart.

Another object of the invention is to provide a catheter and method of the above character in which the amount of rotation or twist of the catheter from a reference position can be ascertained by reading a scale associated with a bubble chamber incorporated as a part of the catheter.

Additional objects and features of the invention will appear from the following description of the particular embodiment as set forth in detail in conjunction with the accompanying drawings:

FIG. 1 is a plan view of a torquable catheter incorporating the present invention.

FIG. 2 is a plan view in cross-section of these steering handle of the catheter shown in FIG. 1.

FIG. 3 is a cross sectional view of the catheter shaft and distal extremity of the catheter shown in FIG. 1.

FIG. 4 is an elevational view of the torque tube utilized in the catheter shown in FIG. 1.

FIG. 5 is a cross-sectional view taken along the line 5--5 of FIG. 4.

FIG. 6 is a cross-sectional view taken along the line 6--6 of FIG. 3.

FIG. 7 is a cross-sectional view taken along the line 7--7 of FIG. 3.

FIG. 8 is a cross-sectional view taken along the line 8--8 of FIG. 2.

FIG. 9 is a plan view of another embodiment of a torquable catheter incorporating the present invention.

FIG. 10 is a cross-sectional view taken along the line 10--10 of FIG. 9.

FIG. 11 is a cross-sectional view taken along the line 11--11 of FIG. 9.

FIG. 12 is a cross-sectional view taken along the line 12--12 of FIG. 9.

FIG. 13 is a cross-sectional view taken along the line 13--13 of FIG. 9.

FIG. 14 is a cross-sectional view taken along the line 14--14 of FIG. 9.

FIG. 15 is a cross-sectional view taken along the line 15--15 of FIG. 9.

FIG. 16 is a cross-sectional view taken along the line 16--16 of FIG. 9.

FIG. 17 is a plan view of still another embodiment of a torquable catheter incorporating the present invention.

FIG. 18 is a cross-sectional view taken along the line 18--18 of FIG. 17.

FIG. 19 is a cross-sectional view taken along the line 19--19 of FIG. 17.

FIG. 20 is a cross-sectional view taken along the line 20--20 of FIG. 17.

FIG. 21 is a cross-sectional view taken along the line 21--21 of FIG. 17.

FIG. 22 is a cross-sectional view taken along the line 22--22 of FIG. 17.

FIG. 23 is a plan view of still another embodiment of a torquable catheter incorporating the present invention.

FIG. 24 is a cross-sectional view taken along the line 24--24 of FIG. 23.

FIG. 25 is a cross-sectional view taken along the line 25--25 of FIG. 23.

FIG. 26 is a side elevational view of a module A utilized in the catheter shown in FIG. 23.

FIG. 27 is a view of a module looking along the line 27--27 of FIG. 26.

FIG. 28 is a view of the module shown in FIG. 27 looking along the line 28--28 of FIG. 26.

FIG. 29 is a side elevational view of another module utilized in the catheter shown in FIG. 23.

FIG. 30 is a view of the module shown in FIG. 29 looking along the line 30--30 of FIG. 29.

FIG. 31 is an end elevation view of the module shown in FIG. 29 looking along the line 31--31.

FIG. 32 is a side elevational view of another module utilized in the catheter as shown in FIG. 23.

FIG. 33 is another view of the module shown in FIG. 32 looking along the line 33--33 of FIG. 32.

FIG. 34 is an end view of the module shown in FIG. 32 looking along the line 34--34 of FIG. 32.

In general, the torquable catheter of the present invention is adapted to be inserted into and through a lumen of a blood vessel and comprises a flexible elongate tube or shaft having proximal and distal extremities and having a lumen extending therethrough. The shaft is comprised of a torque tube extending the length of the shaft. The torque tube has a cylindrical wall, with at least one flexible portion therein. The flexible portion characterized in that a plurality of longitudinally spaced apart slots are provided in the cylindrical wall which extend through the wall with each of the slots subtending less than 360.degree.. A flexible sleeve extends over the torque tube and encases the torque tube which permits flexing of the torque tube within the elastic limits of the torque tube.

More particularly, as shown in the drawings, the torquable catheter 21 incorporating the present invention consists of a flexible elongate tube or shaft 22 having proximal and distal extremities 23 and 24. A steering handle 26 is secured to the proximal extremity 23. At least one electrode, a first electrode 28 and preferably an additional or second electrode 29 are mounted on the distal extremity 24 in a manner hereinafter described.

The catheter shaft 22 consists of a flexible elongate torque tube 31 which extends from the steering handle 26 to near the distal extremity 24 of the catheter shaft. The torque tube 31 is formed of a suitable material such as 13 gauge thin wall stainless steel. Such stainless steel tube 31 has an outer diameter of 0.05" and inside diameter of 0.077" to provide a wall thickness of 0.09". It should be appreciated that it is within the scope of this invention to utilize torque tubes of various diameters and wall thicknesses depending upon the torque capability required for the torque tube 31. For example, utilizing the same diameter, a different wall thickness ranging from 0.007" to 0.012" can be provided. The torque tube can have a suitable length as determined by the length of the catheter 21.

By way of example, a catheter constructed in accordance with the present invention had a torque tube 31 having a length of 38". A torque tube 31 having such a length is elongate and is flexible. However, to impart additional flexibility to the torque tube 31 while retaining its high torque capabilities, the torque tube 31 is provided with at least one flexible portion intermediate its ends and typically is provided with a plurality of such flexible portions. As shown in FIG. 4, three such flexible portions identified as 31a, 31b and 31c are spaced apart longitudinally of the torque tube 31 between the proximal and distal extremities 32 and 33 so that there remains solid portions 31d, 31e, 31f and 31g. The solid portion 31d can be characterized as a shaft portion, the portions 31e and 31f as intermediate portions and portion 31g as a tip portion. The torque tube 31 is formed by an elongate cylindrical wall 36 which has an outer cylindrical surface 37. It also has an inner cylindrical surface 38 which defines a lumen 39 which extends the length of the torque tube 31.

Each of the flexible portions 31a, 31b and 31c is comprised of at least one slot and preferably a plurality of slots 41 which extend through the cylindrical wall 36 and are spaced longitudinally of the torque tube 31. The slots 41 are radially offset with respect to each other. Each of the slots subtends less than one circumference of the tube wall 36 or in other words less than 360.degree.. Preferably the slots subtend an angle ranging from 270.degree. to 300.degree.. Thus, as shown in FIG. 5, there is provided a slot 41 which is cut into the cylindrical wall until the inside surface 38 on the other side of the of the wall 36 is reached so that there remains material in the wall 36 which extends over 0.064" or approximately 60.degree.. The slots 41 are radially offset with respect to each other by a suitable angle as for example 120.degree.. However, these radial offsets can range from 30.degree. to 120.degree.. The slots 41 shown in the drawings extend transversely or normal to the longitudinal axis of the torque tube 31.

It should be appreciated, however, that if desired, the slots 41 can be formed at an angle from portions of a helix.

The distance between each slot 41 in a flexible portion can be defined as the pitch and can range from 0.03" to 0.09" and preferably approximately 0.055". A flexible length of the torque tube 31 can be considered to be a flexible portion associated with a solid wall portion as for example portions 31f and 31c.

The desired degree of flexibility in a flex portion can be varied by providing a fewer or more slots 41 in a flex portion. Thus, there can be provided as few as a single slot to a total of 10 or more slots with the typical flex portion having seven slots as shown in the drawings. In order to give the flexibility of movement of a universal joint at least three slots offset by 120.degree. increments should be provided. Alternatively, four slots offset in 45.degree. can be provided to provide such motion flex portion will permit approximately 30.degree. of bending on a 5/8" inside radius. Thus, two flex portions with no solid tubing in between would permit approximately 60.degree. of bending on a 5/8" inside radius.

By way of example, a torque tube 31 having a length of 38" and made in accordance with the present invention had a tip portion 31g with has a length of 1.5". It had a first flex group comprised of five flex portions each having a length of 1" for a total of 5", a second flex group of seven flex lengths of 11/2" each for a total of 101/2" and a third flex group of 10 flex lengths of 241 each for a total of 20" and a shaft portion 31d having a length of 2". A flex length can be comprised of a single flex section plus a solid length of tubing ending at the first slot in the next flex section. By providing such flex groups, it has been found that the desired flexibility can be achieved for the catheter while still retaining high torque capabilities of the torque tube. It should be appreciated that additional flexibility can be obtained in the catheter by providing additional slots in the torque tube with some sacrifice in the torque capabilities of the torque tube.

A thin walled shrink tubing 46 made of a suitable material such as a polyolefin encapsulates the outer surface 37 of the torque tube 31. The tubing 46 is applied by slipping it over the outer surface 37 of the torque tube 31 and then heating the same to cause it to shrink tightly onto the torque tube 31 to be in direct contact therewith. The shrink tubing 46 serves several purposes. It serves to provide a protective wall for the catheter which encloses the torque tube 31 and provides a smooth outer surface with low friction to engage the wall of the vessel of the patient into which the catheter 21 is introduced. It also serves to prevent undue separation of the segments on the opposite sides of the slots 41.

The shrink tubing 46 is very flexible and permits desired flexing of the torque tube 31 but prevents undue bending or stress in the material of the side wall in any one slot and thereby prevents the placement of a permanent strain in any portion of the tube. In other words, the tubing 46 prevents bending or flexing of the torque tube beyond the point from which it will not yieldably return to its original configuration. The tubing 46 also serves to prevent blood or any other liquid in the lumen in which the catheter is introduced from entering into the slots 41 and causing possible clotting. The shrink tubing 46 can have an appropriate wall thickness such as 0.002" with a wall thickness ranging from 0.01 to 0.004".

A sleeve or tube 48 formed of a suitable insulating material such as a plastic as for example a polyamide is disposed within the torque tube 31 (see FIG. 5) which extends the length of the torque tube 31. An elongate tightly coiled coil spring 51 is disposed within the sleeve or tube 48 and also extends the length of the torque tube 41. The coil spring 51 is formed of a spring steel wire rectangular in cross section. It can have suitable inside and outside diameters, as for example an outside diameter of 0.0360" and an inside diameter of 0.0260" and a wall thickness of 0.005". The wire for the coil spring 51 can have side dimensions of 0.005" for a square cross section. The use of square wire for the coil 51 also serves to prevent collapsing of the turns of the coil during flexing of the catheter.

The distal extremity of the coil spring 51 extends beyond the distal extremity of the tube 31 and extends into a flexible braided tubular member 54 formed of a suitable material such as a plastic with braided wire embedded therein. The braided member 54 which extends within the shrink tubing 46 up to the distal extremity of the torque tube 31 to the line 56 shown in FIG. 3. The distal extremity of the insulating tube 48 extends to the line 57 in FIG. 3. The braided tubular member 54 extends distally beyond the distal extremity of the coil spring 51 and is bonded by a suitable means such as an adhesive (not shown) to a soft plastic tubing 61.

The tubing 61 carries the electrodes utilized in connection with the present catheter and as shown also serves to mount a first or tip electrode 28 and a second or ring electrode 29 hereinbefore described. Conductors 63 and 64 are connected to the electrodes 28 and 29. Conductor 63 extends into a recess 66 in the tip electrode 28 and conductor 64 extends through a hole 67 makes contact with the ring electrode 29.

Means is provided for causing bending of the distal extremity of the catheter and consists of a bendable flat spring element 71 which has a distal extremity 72 that is seated in the recess 66 provided in the tip electrode 28. The spring element also provided with a proximal extremity 73 seated in slots (not shown) in the distal extremity of the coil spring 51 so that the coil spring 51 serves as a substantially incompressible element in the catheter 21. First and second pull wires or elements 76 and 77 have their distal extremities bonded to opposite sides of the flat spring element 71. The pull wires or elements 76 and 77 extend into the proximal extremity of the catheter 21 by extending through the lumen 81 provided interiorly of the coil spring 51.

Another shrink tube 83 is provided and extends from the distal extremity of the coil spring 51. The tube 83 surrounds the first and second pull wires 76 and 77 and the bendable spring element 71 and extends to the tip electrode 28. The recess or cavity 66 of the electrode 28 is filled with a suitable conducting material such as solder which serves to provide electrical contact to the leads 53 and also to hold the pull wires 76 and 77 and the bendable flat spring element 71 in place. An adhesive 86 can be provided in the space between the distal extremity of the tubing 61 and the outer surface of the tip electrode 28. The tip electrode 28 can have a suitable conformation such as spherical or elongate with a hemisphere tip, as shown.

The conductors or leads 63 and 64 for the electrodes 28 and 29 extend into the proximal extremity of the catheter 21 between the coil spring 51 and the braided tubular member 54 and thereafter between the coil spring 51 and the inner surface 38 of the torque tube 31.

As shown, the first and second pull wires 76 and 77 can be in the form of flat wires to minimize their space requirements. These first and second pull wires 76 and 77 can be identified as right and left pull wires extend to the proximal extremity of the catheter 21 through the torque tube 31 as do the conductors 63 and 64 into the steering handle 26.

The steering handle 26 consists of a housing 91 formed of a suitable material such as plastic. The housing 91 is formed of two mating parts 92 and 93 (see FIG. 8) which form two halves of the housing and which are fastened together by ultrasonic welding or an adhesive (see FIG. 1). This housing 91 has a handle portion 91a which is elongate and which is adapted to be engaged by the hand of the user. The housing is provided with a large cylindrical portion 91b which has a steering lever 96 and a locking lever 97 rotatably mounted thereon. The handles 96 and 97 are provided with enlarged finger engaging portions 96a and 97a respectively which extend slightly outward of the cylindrical portion 91b and extend inwardly diametrically of the housing as shown particularly in FIG. 8. The housing 91 is also provided with an elongate portion 91c which receives the proximal extremity of the shaft 22. Means is provided within the housing 91 for connecting the levers 96 and 97 to the pull wires 76 and 77 so that the pull wires can be pulled in accordance with the positioning of the steering lever 96 and locked in place by locking lever 97.

The steering lever 96 is secured to a circular cap 101 which has secured thereto a cylindrical skirt 102 of an eccentric 103. So that the eccentric 103 rotates with the cap 101 as the steering lever 96 is moved. The eccentric 103 is provided with an annular shoulder 104 which rides upon a washer 106 disposed within the part 92. The eccentric 103 is provided with another annular shoulder 107 that engages a shoulder 108 of a lock nut 109 which is threaded onto a cap screw 111. The cap screw 111 is mounted in a circular cap 112 mounted on the housing 91 on the opposite side of the cap 101 and has the locking lever 97 secured thereto. The lock nut 109 is slidably received within a bore 113 provided on a boss 114 formed on the part 93. Means is provided for preventing rotation of the lock nut 109 relative to the boss 114 and consists of a plurality of circumferentially spaced pins 116 that extend into the shoulder 108 of the nut 109 and into the boss 114 to thereby prevent rotation of the lock nut 109 but to permit movement longitudinally of the bore 113. A friction washer 121 is provided between the eccentric 103 and the interior of the housing 93. Another friction washer 122 is provided between the head 123 of the nut 109 and skirt 124 of the circular cap 101. O rings 126 and 127 are provided for forming seals between the circular caps 101 and 112 and the housing 91. The eccentric 103 is provided with an annular shoulder 128 which receives the pull wires 76 and 77. The steering lever 96 is provided with a scale 98 with a "0" indicating a center position and the numbers +1 to +5 indicating clockwise (and -1 to -5) indicating counterclockwise movement of the lever from the center position by approximately 45.degree. in each direction from a marker 99 for a total of approximately 90.degree..

Means is provided for securing the proximal extremities of the pulling wires or elements 76 and 77 of the housing and consists of a holding block 131. The holding block 131 is rectangular in shape and is provided with a pin 132 which is seated within a recess 133. The pull wires 76 and 77 after they leave the eccentric 103 extend forwardly into a lumen 136 of a tension adjustment screw 137 which is provided therewith a slotted adjustment head 138. The adjustment screw 137 is threaded into a nut 139 and is disposed in a slot 141 provided in an H-shaped structure 142 (see FIG. 2) formed integral with the parts 92 and 93. The H-shaped structure 142 includes upstanding leg portions 142 which define a space 143 therebetween and permit adjustment longitudinally of the H-shaped structure 142. From FIG. 2, it can be seen that the coil spring 51 abuts the head 138 of the tension adjustment screw 137. A removable cover 144 is provided in the part 93 to permit access to the head 138 of the adjustment screw 137 to permit adjustment of the tension on the pull wires 76 and 77.

The proximal extremity of the torque tube 31 extends through a twist indicator assembly 151. The twist indicator assembly 151 consists of a housing 152 formed of a suitable material such as plastic. The housing is comprised of an rotatably adjustable intermediate part 153 which is formed of an opaque plastic and end parts 154 and 156. The end part 156 is formed of a transparent plastic and forms an annular bubble chamber 157 which can contain a suitable liquid such as a silicon fluid. A fill plug 158 is provided for filling the bubble chamber 157 and for introducing a small bubble therein in the chamber which can be visible through the transparent end part 156 which will serve to provide a vertical reference for the catheter as hereinafter described.

The intermediate part of 153 is provided with planar surface 161, which can carry indicia as for example, from 1-10 with a zero index indicated 162 and with numbers on one side +1, +2, +3 on one side of zero and -1, -2, -3 on the other side of zero to give an indication as to the extent of rotation or twist of the catheter as hereinafter described. The other end part 154 provided with a truncated conical surface 166 and with a cylindrical skirt 167 which fictionally engages the torque tube 31 so that the housing 152 rotates with the torque tube.

The conductors 63 and 64 extend through the steering handle 26 as shown particularly in FIG. 2 and are disposed beneath the eccentric 103 and in grooves 171 provided in the housing 91 and are connected to cables 172 and 173 (see FIG. 1) which extend through a strain relief fitting 176 mounted in the housing 91 of the steering handle 26. The cable 172 terminates in two conductors 177 and 178 which are connected to terminals 179 and 181 (see FIG. 1). Similarly, the cable 173 terminates in two conductors 182 and 183 which are provided with terminals 184 and 186. The terminals 179 and 181 and 184 and 186 are adapted to be plugged into electronic equipment of a conventional type to provide mapping and/or ablation capabilities as well as diagnostic and pacing capabilities for a catheter of the present invention.

Operation and use of the catheter having high torque capacity shown in FIGS. 108 and method for utilizing the same may now briefly be described as follows. Let it be assumed that it is desired to carry out mapping in a chamber of the heart as for example the right ventricle and thereafter if necessary to carry out an ablation procedure. The catheter can be advanced into the chamber of the heart in a conventional manner as for example, through a femoral artery. The catheter can be advanced into a femoral artery by use of a guiding catheter. The physician while holding the steering handle 26 in one hand introduces the distal extremity of the catheter 21 into the vessel of the patient having a lumen therein. The catheter has sufficient rigidity so that it can be pushed or advanced into the lumen while observing the advancement under a fluoroscope. In view of the fact that the catheter is relatively flexible and small in size, as for example 1/8" or less, it can be readily advanced through the arterial vessel of the patient into a chamber of the heart.

After it has been determined that the distal extremity of the catheter 21 is in the desired chamber of the heart and the electrodes 28 and 29 are positioned therein, mapping procedures can thereafter be carried out. Typically, a mapping procedure is carried out by bringing the electrodes 28 and 29 into contact with the wall defining a chamber of the heart. As soon as they have been brought into contact with the wall, a potential measurement can be made. The positioning of the distal extremity of the catheter so that the electrodes are brought into contact with the wall forming the chamber is carried out by utilizing the first and second or right and left pull wires or elements 76 and 71 to cause bending of the distal extremity of the catheter in a desired direction. This can be accomplished by operating the steering lever 96 to cause bending of the tip in the desired direction. When the desired position is reached, the pull wires 76 and 77 can be locked into position by rotation of the locking lever 97 to fictionally engage the eccentric 103 and hold it in the desired position until the mapping measurement has been completed.

Progressive incremental mapping of the interior of the chamber of the heart can be accomplished by incrementally rotating the distal extremity of the catheter. This is readily accomplished with a catheter of the present invention which has high torque capabilities to make it possible to achieve a one-to-one torquing movement for the distal extremity of the catheter as the steering handle 26 is rotated by the holding hand of the physician. Thus, for example, if it is desired to rotate the distal extremity of the catheter 21 by a suitable incremental rotational movement as for example 5%, this can be accomplished by rotating the steering handle 26 by that amount. The electrodes can then be brought into contact with the wall of the chamber by use of the pull wires 76 and 77 to bend the distal extremity of the catheter by operation of the steering lever 96 by a finger of the holding hand. Another potential measurement can be made. Additional incremental rotation of the distal extremity of the catheter 21 can then be accomplished and thereafter using the pull wires 76 and 77 to achieve appropriate contact with the wall forming the chamber of the heart. Another potential measurement can then be made. In this way the entire circumferential surface defining the chamber can be mapped.

The twist indicator 151 which has been provided makes it possible for the physician to keep track of the rotation which he has imparted to the distal extremity of the catheter from a reference position. The bubble in the bubble chamber provides a vertical reference for the scale or indicia 163 appearing on the annular surface 161 of the twist indicator assembly 151. The physician when he believes he has the catheter in a good position which he wishes to use as a reference rotatably adjusts the intermediate part so that the "0" on the scale 163 is in registration with the bubble in the bubble chamber 157. By observing the bubble and the scale 161, the physician is able to keep track of where the catheter is with respect to the "0" reference position previously set. This makes it possible for the physician to know precisely where in a rotational aspect the distal extremity of the catheter 21 is positioned.

The torque tube 31 within the catheter 21 provides possible to provide very high torque capabilities for the catheter giving a one-to-one torque transmission from the steering handle 26 to the distal extremity of the catheter 21. The construction of the handle is such so that the catheter 21 can be operated with one hand of the physician while the other hand can grasp the handle portion 91a of the steering handle 26 while permitting the fingers of the same hand to operate the steering lever 96 as well as the locking lever 97. The tension adjustment screw 111 is readily adjusted to achieve the desired tension on the pull wires 76 and 77 so that the pull wires 76 and 77 are immediately responsive to the positioning of the steering lever 96 and will cause bending of the distal extremity of the catheter 21 in relatively smooth curves in opposite directions. By observing the scale 98 on the steering lever 96 with respect to the marker 99, the amount of bending and the direction of the bending of the distal extremity of the catheter can be ascertained. By way of example at a certain predetermined scab setting, a J bend is placed in the distal extremity of the catheter 21. The physician by knowing those scale settings can obtain predetermined bends by moving the steering lever 96 to scale settings.

The use of the slotted torque tube 31 makes it possible to achieve the desired degree of flexibility within the catheter while still retaining high torque capability of the catheter so that a one to one relationship between movement of the steering handle and the distal extremity of the tip of the catheter can achieved. These high torque capabilities can be achieved without significantly reducing the longitudinal rigidity of the catheter.

Another embodiment of a torquable catheter incorporating the present invention is shown in FIGS. 9 through 16. As shown therein, the torquable catheter 201 consists of a flexible elongate tube or shaft 202 which has proximal and distal extremities 203 and 204. The steering handle 206 is substantially identical to the steering handle 26 hereinbefore described, and is secured to the proximal extremity 203 of the tube or shaft 202. At least one electrode and preferably first and second electrodes are provided in which the first electrode is in the form of a ring electrode 207 and the second electrode is in the form of a tip electrode 208.

The catheter tube or shaft 202 consists of a flexible elongate torque tube 211 which extends from the steering handle 206 to near the distal extremity 204. In the present embodiment of the torquable catheter 201, the torque tube 211 is formed of TINEL.RTM., an alloy of nickel and titanium manufactured and sold by Raychem Corporation, 300 Constitution Drive, Menlo Park, Calif. 94025. The TINEL has been selected for use in the torque tube 211 because of its superelastic characteristics which provides the desired flexibility, kink resistance, torquability and shape recovery. This TINEL material can be provided in tubular form as shown in FIG. 4 with slots 41 formed therein in the same manner as hereinbefore described. However, because of the superelastic characteristics of the TINEL, it has been found that a different type of joint construction can be utilized because of the capability of TINEL to withstand repeated bending and that much more severe bends can be accommodated without breaking.

The torque tube 211 can have the same dimensions as hereinbefore previously described, as for example, it can be in the form of 13-gauge, thin-wall hypodermic tubing having an outside diameter of 0.095", a wall thickness of 0.009" and an inside diameter of 0.077" to form a bore 213. As also pointed out previously, torque tubes of various diameters and wall thicknesses can be provided depending upon the particular application as hereinbefore previously pointed out. The torque tube 211 has a suitable length as determined by the length of the torquable catheter 201.

In connection with the present invention, it has been found desirable to provide the torque tube 211 in two sections, one section 211a having a length ranging from 2 to 3 feet which provides 4-way or universal joint action, and a second section 211b having a suitable length as for example 2-3 inches which provides 2-way bending. Although the torque tube 211 is flexible and can be bent, additional flexibility is provided in both of the sections 211a and 211b as hereinafter described. In section 211a, opposed semicircular slots 216 are formed in spaced apart positions spaced axially of the section 211a. The slots 216 extend through the wall of the torque tube 211 a sufficient distance so that there remain circumferentially spaced apart hinges 217 which serve to join adjacent parts 218 forming the section 211. As shown, the hinges 217 are spaced 180.degree. apart and can have a suitable thickness as for example 0.006". The slots 216 can have a suitable width as for example 0.012". Every other pair of opposed slots 216 are offset 90.degree. with respect to the adjacent slots as shown in FIG. 9 and by the cross sectional views as shown in FIGS. 11 and 12. The slots 216 can be formed in a suitable manner as for example by a spark erosion technique identified as EDM machining.

By offsetting the pairs of slots 216 in this manner, it is possible to achieve 4-way bending of the torque tube which is very similar to a universal joint action. By way of example, utilizing the dimensions set forth above, it has been found that a 180.degree. bend can be achieved in less than 2 inches of the torque tube section 211a. It should be readily appreciated that the amount of bending is determined by the spacing between the pairs of opposed slots 216 and also the width of the slots, with the width of the slot determining the amount of bending which can occur between any two adjacent parts of the section 211a.

By providing two hinges 217 between adjacent parts 218 there is increased capability of transferring torque from one part to the other over the embodiment which is shown in FIG. 4 in which only a single portion 41 remains to transfer torque from one adjacent part to another. By utilizing the superelastic TINEL as the material for the torque tube 211, the hinges 217 are also superelastic and provide the capability for repeated hinging without danger of breaking.

As shown in FIG. 10, the proximal extremity of the section 211a of the torque tube 211 is provided with an annular recess 221 to provide a cylindrical portion 222 of reduced diameter which has formed thereon a pair of teats 223 spaced 180.degree. apart having lips 224 which are adapted to seat in bores 226 spaced 180.degree. apart and extending at right angles to the axis of the torque tube 211 in the cylindrical member 227 which corresponds to the portion 91a of the handle 26 as shown in FIG. 2. In this way it can be seen that the section 211a of the torque tube 211 can be snapped into position in engagement with the handle by the lips 224 of the teats 223 being seated within the bores 226.

The distal extremity of the section 211a is provided within a large cylindrical recess 231 which opens forwardly. A pair of diametrically opposed bores 232 are provided in the distal-most part 218 of the section 211a and extend perpendicular to the axis of the section 211a and open into the cylindrical recess 231. A flanged insert 233 has its flange disposed within the cylindrical recess 231 with the remaining portion thereof extending into the adjacent part 218. A plurality of circumferentially spaced-apart slots 234 are provided in the insert 233 and extend in a direction parallel to the axis of the flanged insert 233. By way of example as shown in FIG. 13, eight of such slots 234 can be provided which are equally spaced apart around the circumference of the flanged insert 233. The slots 234 are used for purposes hereinafter described.

The torque tube section 211b is formed in a manner similar to that utilized for section 211a, the principal differences being that alternate opposed sets of slots are not offset by 90.degree. because it is only desired to achieve 2-way bending by the relatively short tip section 211b. Thus, there are provided pairs of opposed slots 236 having a suitable width as for example 0.012" spaced apart a suitable distance as for example 0.011". The slots 236 are cut to a sufficient depth so that there remain a pair of hinges 237 spaced 180.degree. apart which form connections between adjacent parts 238 of the section 211b. It can be seen that the hinges 237 lie in a single plane so as to permit bending in only two directions, forward and back with respect to the hinges 237. The hinges again have a suitable width as for example 0.006". The most proximal part of the section 211b is provided with an annular recess to provide a cylindrical portion on which there are provided a pair of teats 239 spaced 180.degree. apart having the same shape as the teats 223. These teats 239 engage the bores 232 in the section 211a.

In order to provide a return memory at the distal extremity of the torque tube 211, "TINEL" superelastic wire 244 by Raychem Corporation, 300 Constitution Drive, Menlo Park, Calif. 94025, is utilized having a diameter ranging from 0.008" to 0.012" and preferably a diameter of 0.010", which extends longitudinally of the section 211b through the hinges 237 as shown particularly in FIG. 15. This superelastic wire, because it provides extreme flexibility, is kink resistant and provides shape recovery to the distal extremity of the torquable catheter when the distal extremity is permitted to return to its original condition.

The most distal part of the section 211b is provided with a large cylindrical recess 241. A pair of bores 242 spaced 180.degree. apart extend into the recess 241 at right angles to the axis of the recess. A ring electrode retainer 246 is mounted within the recess 241. The retainer 246 is provided with cylindrical portions 246a and 246b of reduced diameter. The ring electrode 207 is mounted on the portion 246. A pair of teats 247 are spaced 180.degree. apart and are provided on the portion 246b and are seated within the bores 242. A retainer 246 is provided with a bore 248 which is of the same size and is in registration with the bore 213 of the sections 211a and 211b. An enlarged cylindrical recess 249 is provided in the retainer 246. A pair of oppositely disposed bores 251 are provided in the retainer 246 and open into the cylindrical recess 249 at right angles to the axis of the recess. A flanged insert 252 similar to the flanged insert 233 hereinbefore described is disposed within the cylindrical recess 249 and is provided with circumferentially spaced slots 253. The tip electrode 208 is formed of a suitable material and is formed as a cylinder which is provided with a hemispherical distal surface. The tip electrode 208 is mounted upon cylindrical tip electrode mounting 256 in a suitable manner. The mounting 256 is provided with a pair of teats 257 spaced 180.degree. apart which are seated within the bores 251 of the retainer 246.

The flanged inserts 233 and 252, as well as the retainer 246 and the top electrode mounting 256, can be formed of a suitable material such as plastic.

A protective cover 261 formed of shrink tubing similar to the shrink tubing 46 hereinbefore described is provided. This shrink tubing is formed of polyolefin and encapsulates the outer surface of the torque tube 211 and extends from the ring electrode 207 at the distal extremity from the ring electrode 207 at the distal extremity to the proximal extremity adjacent the steering handle 206. As pointed out previously, the protective cover 261 serves to prevent blood and other body fluids from entering into the slotted torque tube 211 while still permitting the desired bending of the torque tube. It also provides a smooth outer surface with low friction to facilitate movement of the torquable catheter tool in a vessel. As pointed out previously, the protective cover 261 can have a suitable wall thickness ranging from 0.001" to 0.004" and preferably 0.002".

An elongate, tightly coiled coil spring 263 is provided within the torque tube 211 and extends from the insert 233 to within the proximal extremity of the handle 206 as shown in FIG. 9. It can be sized so it fits within the torque tube 211 and, as pointed out previously, can be of square cross section to obtain the tight coiling to prevent collapsing of the turns of the coil on each other during flexing and compression of the coil spring.

First and second or right and left pull wires 264 and 266 are provided within the coil spring 263 and are connected to handle 206 in the same manner that the pull wires in the previous embodiments are connected to the handle 26. The pull wires 264 and 266 extend from the handle 206 through the coil spring 263 and thence through the central bore 267 provided in the insert 233 and then through the section 211b of the torque tube 211 and through two of the recesses 253 provided in the insert 252. The distal extremities of the pull wires 264 and 266 are then bent over the distal extremity of the insert 252 and are secured thereto by suitable means such as an adhesive.

The pull wires 264 and 266 can be formed of a suitable material such as TINEL superelastic wire supplied by Raychem Corporation, 300 Constitution Drive, Menlo Park, Calif. 94025. The use of such a material for the pull wires 264 and 266 is desirable because of its good flexibility, its kink resistance, and its shape recovery which facilitates returning the distal extremity of the torquable catheter 201 to its normally relatively straight condition from a bent position into which it is formed by operation of the handle 206 on the pull wires 264 and 266.

First and second insulated conductors 271 and 272 extend from the handle 206 and into the section 211a of the torque tube 211 between the interior of the torque tube section 211a and the exterior of the coil spring 263 and then through two of the recesses 234 of the insert 233 as shown in FIG. 13, and then through the torque tube section 211b through the retainer 246 through slot 253 in the insert 252 and then into the mounting 256 where it is connected to the tip electrode 208 by suitable means, such as soldering. The insulated connector 272 extends through a slot 273 provided in the retainer 246 and is secured to the ring electrode 207 by suitable means such as soldering.

The operation and use of the torquable catheter 201 as shown in FIGS. 9 through 16 and the method for utilizing the same is very similar to that hereinbefore described with respect to the previous embodiments. However, it should be appreciated that the torquable catheter tool which is provided with the TINEL torque tube provides extreme flexibility making it possible to bend the distal extremity of the catheter about a relatively sharp curve by operation of the handle 206 in either of two directions in a single plane. With rotation of the torquable catheter 201 by turning or rotation of the handle 206 it is possible to position the distal extremity of the torquable catheter 201 in any desired position within a chamber of the heart. The use of the TINEL pull wires 264 and 266 aids in returning the distal extremity of the catheter into its normal position. The use of the TINEL hinges interconnecting the parts provides excellent torque transmission characteristics between the parts while at the same time permitting repeated bending of the torquable catheter without danger of the hinges breaking or failing.

Still another embodiment of a torquable catheter 301 incorporating the present invention is shown in FIGS. 17 through 22. The torquable catheter 301 consists of the flexible elongate tube or shaft 302 having proximal and distal extremities 303 and 304. The proximal extremity is connected to a steering handle 306 of the type hereinbefore described. The catheter shaft 302 consists of a flexible elongate torque tube 307 which is formed of a plastic. A plastic suitable for this purpose is polypropylene which, in addition to being very strong, provides a desired hinge action which may be flexed repeatedly, as for example millions of times, without breaking.

The torque tube 307 is formed in two sections 307a and 307b, in which section 307a permits 4-way bending whereas section 307b permits 2-way bending as described in connection with a previous embodiment of the torquable catheter. The section 307a has a length of 2-3 feet and section 307b has a length of 2-4 inches. Section 307a is provided with paris of opposed semicircular slots 308 which extend through the wall of the plastic torque tube 307 a sufficient distance so that there remains a pair of hinges 309 which are spaced 180.degree. apart having a suitable width as for example 0.006" and with the slots having a width of suitable dimensions as for example 0.012". The pairs of opposed slots 308 are spaced apart by a suitable distance as for example 0.100", with every other pair of slots being offset by 90.degree. so that the hinges 309 lie in two planes which are angularly offset with respect to each by 90.degree. to provide the 4-way bending similar to that obtained by universal joint hereinbefore described. The hinges 309 provided benign between adjacent parts 311 to permit flexing of the hinges between the parts in an amount determined by the width of the slots 308.

The section 307a can be formed of one or more units 312 as for example units having a length of 4 to 6 inches which are fitted together as hereinafter described to provide the 4-way section 307a of a suitable length as for example 2 to 3 feet. The unit 312 can be provided with mating proximal and distal extremities in which a cylindrical portion 313 of reduced diameter is provided having oppositely disposed teats spaced 180.degree. apart being provided thereon. The distal extremity is provided with an enlarged cylindrical recess 316 which is sized to fit the cylindrical portion or extension 313 of reduced diameter and is provided with bores 317 spaced 180.degree. apart and opening into the recess 316 at right angels thereto. The bores 317 are adapted to receive the teats 314 making it possible to secure the units to each other in a linear fashion to provide a 4-way bendable section 307a of a desired length. A pair of interiorly disposed slots 318 are provided within each of the units 312 and are spaced 180.degree. apart and open into a central bore 319 which extends through each of the units 312 for receiving first and second pull wires 321 and 322. An elongate coil spring 324 of the type hereinbefore described is provided within the section 307a and extends the length of the same as hereinafter described.

The 2-way bendable section 307b is provided with opposed semi-circular slots 326 which extend substantially through the wall of the tubular section 307b so that there remains a pair of hinges 317 spaced 180.degree. apart. The slots 326 have a suitable width as for example 0.012" and are spaced apart a suitable distance as for example 0.100" to provide hinges 327 between parts 328 which lie on a plane so as to permit flexing in two directions. The proximal extremity of the section 307b is connected to the distal extremity of the section 307a by a cylindrical spring backup module 331 which is provided with a cylindrical extension 332 having teats 33 provided 180.degree. apart thereon which engage the bores 317 in the distal extremity of the spring 324 abuts against the cylindrical extension 332. The other end of the spring backup module 331 is provided with a cylindrical recess 334 having diametrically extending bores 336 extending into the recess. The proximal extremity of the section 307b is provided with a cylindrical extension 337 having teats 338 mounted thereon spaced 180.degree. apart which are received by the bores 336 to secure the section 307b to the section 307a.

In a similar manner, the distal extremity of the section 307b is provided with a cylindrical recess 341 having diametrically extending bores 342 opening therein. The recess 341 is adapted to have mounted therein a cylindrical steering wire retainer 346 which is provided with a cylindrical extension 347 having a pair of teats 348 mounted 180.degree. apart thereon which are adapted to seat in the bores 342. The pull wires 321 and 322, which also can be called steering wires, extend through the section 307a between the interior of the section 307a ad the exterior of the coil spring 324 through the spring backup module 331 and then through the section 307b disposed in elongate recesses 349 provided therein on opposite sides of a central open bore 351 which extends through the section 307b. The pull wires 321 and 322 can be formed of a suitable material such as KEVLAR. The distal extremities of the pull wires 321 and 322 extend into the steering wire retainer 346 and are secured therein by a retaining ring 352 which is secured to the retainer by suitable means such as an adhesive. The retaining ring 352 is provided with a central bore 353 which is in axial alignment with the bore 351 of the section 307b.

If desired, a soft tip 356 formed of a suitable material such as a latex can be removably secured to the distal extremity of the retainer 346.

The bore 351 in the section 307 is in axial alignment with the bore 361 provided in the spring backup module 331 and with the central bore provided in the spring 324.

A protective cover 366 formed of a suitable material such as polyolefin shrink tubing is provided for the exterior of the torque tube 307 and extends from the distal extremity of the catheter from the retainer 346 over the sections 307b and 307a up to a wye adapter 368 into which the torque tube section 307a extends with the coil spring 324 therein as shown in FIG. 17.

In order to provide shape recovery to the distal extremity of the torquable catheter 301, a pair of superelastic wires formed of a suitable material such as TINEL of a suitable size such as 0.010" in diameter are provided in the section 307b of the torque tube 307. As shown particularly in FIG. 21, these wires 371 and 372 are insert-molded into the hinges 327 of the section 307b and extend longitudinally through the length thereof. These superelastic insert-molded wires 371 and 372 urge the distal extremity 304 to its normally straight condition after it has been formed into a bend by the steering handle 306 and then released.

The wye adapter 368 is provided with a central leg or arm 376 which has a central bore 377 therein through which the pull wires 321 and 322 extend. The central arm 376 is provided with a fitting 378 which is adapted to be secured to the handle 306 in the manner hereinbefore described with respect to the previous embodiments of the torquable catheter. The pull wires 321 and 322 are connected into the handle in the same manner and are operated in the same manner to provide the desired bending of the distal extremity of the catheter 301.

The wye adapter 368 is also provided with a side arm 381 which is provided with a central bore 382 that is in communication with a bore 383 which is in communication with the bore 361 extending through the coil spring 324. The side arm 381 is also provided with an O-ring 386 and a thumbscrew 387 which is threaded therein, and is adapted to clamp the O-ring 386 about any device (not shown) which extends through a bore 388 provided in the thumbscrew 387 through the O-ring 386 and into the bores 382 and 383. Such a device can extend into the bore 361 of the coil spring 324 and through the bores 351 and 353 provided in the distal extremity of the catheter and out through the open end. Thus, by way of example in connection with the present invention, it is possible to readily provide a open central lumen access having a diameter of 0.052" through the 2-way flex section 307b and a 0.038" diameter central lumen access through the 4-way flex section 307a. It can be readily be seen that this central lumen is a size that can accept many different types of medical devices for conducting operations in the human body.

The operation and use of the torquable catheter 301 is very similar to that hereinbefore described with the exception that rather than being utilized for mapping and ablation, the present torquable catheter can be utilized in conjunction with other devices for performing various types of operations in the human body. The distal extremity of the torquable catheter can be bent into any desired conformation by the steering handle 306 by operations on the pull wires 321 and 322. When the pull wires 321 and 322 are released, the distal extremity of the catheter will be urged to return to its normal relatively straight condition by the superelastic TINEL wires 371 and 372. The use of the wye adapter 368 permits insertion of medical devices into the body without loss of blood or other fluids by use of the thumbscrew 387 clamping the O-ring 386 about the device after it has been positioned within the human body.

Still another embodiment of a torquable catheter 401 incorporating the present invention is shown in FIGS. 23 through 34. As shown therein, it consists of a shaft 402 which is provided with proximal and distal extremities 403 and 404. The shaft 402 consists of a flexible elongate torque tube 406. The torque tube 406 consists of a 4-way bend section 407 which is comprised of a plurality of axially aligned joined-together modules 408 and the 2-way bend section 409 which is comprised of axially aligned joined-together modules 411 and 412.

The modules 408, 411 and 412 are formed of a suitable material such as an injection moldable plastic material such as polypropylene which is capable of providing living hinges as hereinafter described.

The module 408 is in the form of a cylinder and has a suitable dimension such as an outside diameter of 0.095" and a cylindrical 414 extending longitudinally thereof and having a diameter of a suitable dimension as for example 0.060" to provide a cylindrical wall 416 having a thickness of 0.0175". The module 408 can have a suitable length as for example 0.188". A pair of longitudinally extending tangs or legs 417 are provided which are formed integral with the wall 416 and are disposed parallel to the longitudinal axis of the bore 414. The legs 417 can have a suitable length as for example 0.042" and have a width of 0.018" and a thickness of 0.010". The legs 417 are provided with portions which have a reduced cross section in a direction perpendicular to the longitudinal axis of the bore 414 and serve to form "living hinges" to permit repeated flexing without breaking of the legs with respect to the wall 416 as hereinafter described. Ears 419 are formed integral with the outer extremities of the legs 417 and are generally rectangular in cross section and can have a suitable thickness as for example 0.018" and a length of 0.018" inches. The hinges 418 are formed by providing radii of a suitable size as for example 0.006" in a hinge having a length of 0.012". A pair of recesses 421 are provided in the outer surface of the wall 416 on the end opposite the legs 417 spaced 180.degree. apart which are offset 90.degree. with respect to the legs 417 of another module 408. The recesses 421 are sized so that they can receive the legs 417 of another module 408 and have a width of approximately 0.018" and a length of 0.030". The recesses 421 extend into rectangular recesses or holes 422 which extend through the wall 416. These holes or recesses 422 are dimensioned to receive the ears 419 and thus are provided with sides having a dimension of 0.018".

It can be seen that the holes or recesses 422 are positioned in such a manner so that when the modules 408 are assembled as shown in FIG. 23 with the legs 417 extending into the recesses 421 and with the ears 419 seated within the holes or recesses 422, there is provided a spacing between the axially aligned, joined modules 408 of a suitable dimension as for example 0.012" corresponding to the length of the hinges 418 so as to permit bending of the modules 408 with respect to each other in a 4-way motion which is similar to the universal joint action hereinbefore described. As can be seen, ending of one module with respect to the other in a pair of modules 408 can occur in two directions at right angles to the hinges 418 whereas another pair of modules can be bent in two different directions offset by 180.degree. with respect to the directions in which the modules in the first-named pair can be bent.

The modules 411 forming a part of the 2-way bend section 409 are also of cylindrical form and can have an outside dimension as for example 0.095" and a length of 0.114" with a cylindrical bore 426 having a suitable diameter as for example 0.060" to provide a wall 427 having a thickness of 0.0175". Pairs of recesses 428 and 429 spaced 180.degree. apart are provided on opposite ends of the cylindrical wall 427 and extend through the outer surface thereof and are in axial alignment with each other and extend longitudinally of the bore 426. The recesses 428 and 429 open respectively into rectangular recesses or holes 431 and 432 provided in the wall 427. These recesses 428 and 429 and the holes or recesses 431 and 432 are dimensioned in a manner similar to the recesses 421 and the holes or recesses 422 in the module 408.

The module 412 is also cylindrical in shape and is provided with an outside diameter of 0.095" with a cylindrical bore 436 extending longitudinally therethrough and having a diameter of 0.060" and a wall 437 having a thickness of 0.0175". Pairs of legs 438 and 439 are formed integral with the wall on opposite ends of the wall 437 and extend outwardly therefrom. The legs in each pair spaced 180.degree. apart are in axial alignment with the legs of the other pair. The legs can have suitable dimensions as for example a length of 0.060" and a width of 0.018". Hinges 441 and 442 are formed by providing portions of reduced cross sectional area and width of the legs by providing hinges having a length of 0.012" and by forming radiuses of 0.006". Rectangular ears 443 and 444 are provided on the outward extremities of the legs 438 and 439 and have suitable dimensions as for example 0.018" by 0.018". The ears 443 and 444 and the legs 438 and 439 are dimensioned so that they can fit within the recesses 428 and 429 and 431 and 432 provided in the module 411.

As can be seen in FIG. 23, the modules 411 and 412 are joined together by snapping the legs 438 and 439 into the recesses 428 and 429 so that the ears 443 and 444 snap into the recesses 431 and 432 to provide the 2-way bend section 409 so that the hinges 441 and 442 are axially aligned and to provide a suitable spacing between the modules as for example 0.12" to permit 2-way bending of this section of the shaft.

A cover 451 of shrink tubing is provided on the exterior of the assembled modules 408, 411 and 412. This cover 451 ensures that the modules 408, 411 and 412 will remain joined together by preventing the tangs or legs with their ears formed integral therewith from disengaging the corresponding recesses or popping apart. The shrink tubing also prevents the bending of the modules with respect to each other within the limits of the spacing provided between the modules and the hinges joining the modules. The shrink tubing cover 451 also serves to prevent blood from entering into the lumen of the catheter formed by the respective bores provided in the modules. The shrink tubing made of a suitable material such as polyolefin permits easy flexing and bending of the shaft 402 of the catheter 401.

When utilized in the catheter as for example of the type hereinbefore described, the 4-way bend section 407 can have a suitable length as for example 2-3 feet whereas the 2-way bend section 409 can have a suitable length as for example 2-3 inches. In this way it is possible to provide a catheter a which is very flexible and in which the bending in the distal extremity is limited to 2-way bending to facilitate positioning of the distal extremity while at the same time providing excellent torque transmission from the proximal to the distal extremity of the shaft 402.

The modular type construction which is shown in FIG. 23 lends itself to use in various types of torquable catheters. As in the previous embodiments, the proximal extremity can be connected to a steering handle (not shown) of the type hereinbefore described in which the pair of pull wires (not shown) can extend through the central lumen. In addition, it should be appreciated that if desired the 4-way bend section can be provided with a coil spring disposed interiorally of the lumen as described in the previous embodiments. If electrodes are to be carried by the distal extremity of the catheter, the conductive wires connected thereto also can extend through the lumen and then through the steering handle in the manner hereinbefore described. Also it should be appreciated that since a large central lumen has been provided in the catheter other types of medical type devices can be inserted through this lumen for performing operations at the distal extremity of the catheter.

Other embodiments of the invention within the scope of the present invention can utilize different electrode tip configuration to achieve desired diagnostic and pacing functions as well as mapping and/or ablation. In conjunction therewith radio frequency and microwave energy can be utilized when desired.