Guide wire for use in measuring a characteristic of liquid flow in a vessel

Abstract: A guide (101) wire for use in measuring a characteristic of liquid flow in a vessel includes a flexible elongate tubular element (102) having proximal and distal extremities. A core wire (103) extends through at least a portion of the flexible elongate element and has a tapered distal extremity (104) extending beyond the distal extremity of the tubular element. A coil (106) extends over and beyond the distal extremity of the core wire. A transducer (111) is secured to the distal extremity (109) of the coil. First and second conductor means (118) are carried by the tubular element and are connected to the transducer, extending to the distal extremity (119) of the tubular element (102). Means (107) are provided for bonding the tubular element (102) to the core wire (103) and the coil (106) to the tubular element (102) and to the core wire so that torsional forces applied to the tubular element are supplied to the coil spring.

Description: This invention relates generally to a guide wire for use in measuring a characteristic of liquid flow in a vessel, and in particular to a guide wire for blood flow velocity measurements in a vessel. A device for use in measuring a characteristic of liquid flow in a vessel and in particular for blood flow velocity measurements in a vessel is disclosed in EP-A-0286359. According to the present invention there is provided a device for use in measuring a characteristic of liquid flow in a vessel comprising a flexible elongate tubular element having proximal and distal extremities with a passage extending from the proximal extremity to the distal extremity and having a wall defined by the distal extremity of the flexible elongate element, a coil spring having a distal extremity, a transducer carried by the distal extremity of the coil spring and conductive means connected to the transducer and extending interiorly of the coil spring and through the passage in the flexible elongate tubular element, characterized by the distal extremity of the flexible elongate tubular member being provided with threads therein, the coil spring being threaded into said threads and being secured thereby to the distal extremity of the flexible elongate tubular member to form a mechanical connection therebetween. An embodiment of the invention provides a guide wire of the above character which has excellent torsional and mechanical properties. An embodiment of the invention provides a guide wire of the above character which is provided with a screw joint for securing the transducer. Additional objects and features of the present invention will appear from the following description in which the preferred embodiments are set forth in detail in conjunction with the accompanying drawings. Figures 1 through 5 and the description associated therewith are disclosed in European Patent Application No. 0286359 published on October 12, 1988 and have been deleted from this application since the subject matter thereof is not being claimed. Figures 6 to 17 and the description associated therewith have been deleted from this application. Figure 18 is a partial view partially in cross section of an embodiment of a guide wire incorporating the present invention utilizing screw joints. Figure 19 is a cross sectional view taken along the line 19-19 of Figure 18. Figure 20 is a cross sectional view taken along the line 20-20 of Figure 18. Figure 21 is a cross sectional view taken along the line 21-21 of Figure 18. Figure 22 is a view of a portion of a guide wire incorporating the present invention which is partially in cross section showing the use of an intermediate screw joint. Figure 23 is a cross sectional view taken along the line 23-23 of Figure 22. Figure 24 is an elevational view of an intermediate screw joint used in the guide wire shown in Figures 22 and 23. An embodiment of the guide wire incorporating the present invention utilizing screw joints is shown in Figures 18 through 21 and is of a type which incorporates screw joints. The guide wire 281 shown in Figure 18 consists of a flexible elongate member 282 in the form of stainless steel hypodermic tubing of the same dimensions described in conjunction with the guide wires shown in Figure 15. The elongate member 282 is provided with a passage 283 extending therethrough. The elongate member 282 is provided with a distal extremity 284. A helical slot 286 is cut into the exterior surface of the distal extremity 284 and extends through the wall of the hypodermic tubing 282 to form threads. The helical slots 286 can be formed in a suitable manner such as by machining. Such a density would provide threads with a helix angle of 9.50' and a pitch of 0.235mm (0.00926 inches). Such helical slots can be formed by utilizing a diamond dicing saw with a very thin blade having a thickness ranging from 0.038 to 0.025mm (0.0015 to 0.0010 inches) and by utilizing a helical drive mechanism to feed the distal extremity 284 into the diamond dicing saw. Typically, the hypodermic tubing forming the elongate member 282 has an outside diameter ranging from 0.43 to 0.45mm (0.017 to 0.0178 inches) and is coated with a suitable lubricant such as Teflon to facilitate movement of the guide wire 281 in a vessel of a patient. The inside diameter of the hypodermic tubing can vary from 0.36 to 0.38mm (0.014 to 0.015 inches) to provide a wall thickness ranging from 0.038mm (0.0015 inches) to 0.064mm (0.0025 inches). The helical slot or groove 286 has a width which can range from 0.064 to 0.11mm (0.0025 to 0.0045 inches). The threads formed by slot or groove 286 have a density which can range from 2.95 to 6 per mm (75 to 150 per inch) and preferably about 4.3 per mm (108 per inch) for tubing having a diameter of 0.46mm (0.018 inches) or less. An insulating and protective tube 287 formed of a suitable material such as polyimide is disposed in the passage 283 of the hypodermic tubing 282 and extends beyond the distal extremity 284 of the hypodermic tubing. A coil 288 formed of a suitable material such as stainless steel is threaded into the helical slots or grooves 286 and extends over the portion of the insulating tube 287 extending beyond the distal extremity 284 of the elongate member 282. This connection serves to form a screw joint 289 rather than the solder joint hereinbefore described. To provide high x-ray visibility, a palladium coil 291 is threaded into the stainless steel coil 288 as shown in Figure 18 and solder 292 is applied to provide a solder screw joint 293 between the stainless steel coil 288 and the palladium coil 291. A screw tip 296 is provided and can be formed of a suitable material such as stainless steel and have the same dimensions as the hypodermic tubing forming the elongate member 282. THe tip can have a suitable length such as 1.27 to 1.52mm (0.050 to 0.060 inches). A helical thread or recess 297 is formed in the exterior surface of the tip 296 and receives the distal extremity of the palladium coil 291. The helical recess 297 is formed in a manner similar to the helical slots 286. However, rather than being cut all the way through as with the helical slots 286, the helical recess 297 extends only through a portion of the wall forming the tip 296. Thus, with the wall thickness of 0.10 to 0.13mm (0.004 to 0.005 inches) the recess or thread can have a depth ranging from 0.064 to 0.097mm (0.0025 to 0.0038 inches) and can be squared or have a full radius. When the tip 296 is threaded into the distal extremity of the coil 291, the tip itself is aligned with respect to the coil 291. The tip 296 is provided with a cylindrical recess 301 at its distal extremity which opens in a forward direction. The recess 301 can have a depth ranging from 0.38 to 0.51mm (0.015 to 0.020 inches) and can have a diameter ranging from 0.39 to 0.42mm (0.0155 to 0.0166 inches). A Doppler transducer 302 and a lens 303 are disposed within the recess 301 and are adhered therein by suitable means such as an adhesive 304 disposed between the side wall of the recess 301 and the transducer 302 so that the rear of the transducer is free or in air. A core wire 306 formed of a suitable material such as stainless steel extends through the insulating and protective tube 287 and is provided with a tapered distal extremity 307 which adjoins a shaping ribbon 308 having a rectangular configuration and which is secured to the screw tip 296 by suitable means such as solder 309. The screw tip 296 in addition to being threaded into the coil 291 also has the coil soldered to the tip. Conductive leads 311 and 312 are provided which extend within the insulating and protective tube 286 and over the core wire 306. They are connected to the front and back sides of the transducers 302 as shown particularly in Figure 18. The entire coil assembly or means comprised of the coils 288 and 291 and the screw joint 293 and the screw tip 296 is Parylene coated in the manner hereinbefore described for the previous embodiments. Operation and use of guide wires such as the guide wire 281 is conventional. The constructions which are shown in Figures 18-24 provide a superior guide wire. However, this does not change the mode of operation of the guide wire. The transducer 302 and the lens 303 are incorporated in an assembly which is very difficult to separate from the remainder of the guide wire. This is accomplished by placing the transducer 302 and the lens in the cup-shaped recess 301 provided at the tip of the guide wire. Tip separation is also prevented by the use of the soldered screw tip 296 configuration which is utilized for securing the tip 296 to the coil 291. An excellent mechanical joint is provided for securing the tip 296 to the coil 291. The recessing of the transducer 302 which is in the form of a Doppler crystal holds the same in place so there is no chance of the transducer 302 and the lens 303 being separated from the tip 296. The screw joints provided in the guide wire 281 in addition to providing better mechanical connections also provides the advantage of providing strain relief transitions from the relatively stiff hypo tube forming the elongate member 282 to the flexible coil 288 used at the tip and also a similar transition between the coil 291 and the tip 296. Therefore the construction of the present embodiment provides very strong joints which have excellent tensile and bending load characteristics. It should be appreciated that the cup-shaped recess 301 which is provided can be utilized for accommodating various types of transducers other than the Doppler crystal hereinbefore described. For example, it can be utilized for housing various types of sensors as, for example, a pressure transducer. The same principles which have been utilized in the distal extremity of the guide wire 281 can also be utilized in the proximal extremity in which helical slots 316 are provided in the proximal extremity of the hypodermic tubing forming the flexible elongate member 282. A coil spring 317 formed of a suitable material such as stainless steel is threaded into the slots 316 as shown in Figure 18. The insulating sleeve 287 extends beyond the coil spring 317. A connector 321 is mounted in the spring 317 and extends into the proximal extremity of the hypodermic tubing 282 and is secured therein by suitable means such as an adhesive. The connector 321 is formed of a suitable conducting material such as stainless steel. It serves the same purpose as the connector 276 shown in Figure 15. In Figure 18, the proximal extremity of the connector 321 is not crimped. It can be provided with a crimp if desired of the type shown in Figure 15. If not desired, a non-crimped cylindrical connector 321 can be provided as shown in Figure 18. In order to accommodate the conducting wires 311 and 312, the portion of the connector 321 disposed within the proximal extremity of the hypodermic tubing 282 is provided with flats 322 and 323 as shown in Figure 21. The construction shown for the proximal extremity of the guide wire 282 has the same advantages as the construction provided on the distal extremity of the guide wire. A good mechanical connection is provided between the hypodermic tubing 282 and the coil spring 317 and the connector 321. The coil spring also provides a strain relief transition from the hypodermic tubing 282 to the connector 321. One of the principal advantages of mounting the transducer 302 within the cup-shaped recess 301 is that the adhesive 304 is provided on the circumference of the transducer 302 but is not provided to the rear of the transducer so that the rear or back side of the transducer 302 is exposed to air and can readily flex. This enhances the Doppler capabilities of the crystal or transducer. It should be appreciated that with these screw type joints provided in the guide wire 281, the springs are threaded into the helices of the guide wire to provide an integrated construction. However, it should be appreciated that a non-integral construction could be provided by bonding the coil to the hypodermic tubing without threading the coil into the helices. It is believed that this is not as desirable because not as good a mechanical connection is provided. However, such a construction would provide a gradual transition in stiffness from the hypoderic tubing to the coil spring. Another embodiment of a screw joint connection which can be utilized in the guide wire 281 is shown in Figures 22-24. As shown therein, rather than two coils 288 and 291 being threaded together as disclosed in Figure 18, they are interconnected by an intermediate screw joint 331. The intermediate screw joint 331 is formed of a length of hypodermic tubing 332 of the same type utilized for the elongate member 282 and is provided with helical recesses 333 and 334 at opposite ends which are formed in the same manner as the helical recesses 297 in the tip 296. As shown in Figure 22, the screw joint 331 is utilized for interconnecting the two coils 288 and 291 by threading the coil 288 into the helical recesses 333 and threading the coil 291 into the helical recesses 334. The conductors 311 and 312 and the shaping ribbon 308 extend through the screw joint 331 in the manner shown. From this construction, it can be seen that a strong mechanical connection with good alignment has been provided between the two coils 288 and 291. The entire assembly which is shown in Figure 22 can be Parylene coated in the manner hereinbefore described. It is apparent from the foregoing that there has been provided a guide wire for measuring blood flow velocity in a vessel. This can be accomplished by the use of a single transducer positioned intravascularly to produce a beam of uniform insonification which encompasses the entirety of the blood vessel. It should be appreciated that although the present invention has been described particularly for use in the measuring of blood flow velocity in a vessel, the present invention also can be utilized for measuring other liquids in other types of conduits if desired.

Claims: A device (281) for use in measuring a characteristic of liquid flow in a vessel comprising a flexible elongate tubular element having proximal and distal extremities with a passage (283) extending from the proximal extremity to the distal extremity and having a wall defined by the distal extremity of the flexible elongate element, a coil spring having a distal extremity, a transducer (302) carried by the distal extremity of the coil spring (288) and conductive means (311, 312) connected to the transducer and extending interiorly of the coil spring and through the passage (283) in the flexible elongate tubular element, characterized by the distal extremity of the flexible elongate tubular member being provided with threads (286) therein, the coil spring (288) being threaded into said threads and being secured thereby to the distal extremity of the flexible elongate tubular member to form a mechanical connection therebetween. A device as in Claim 1 further characterized in that the wall of the tubular member has an exterior surface and that the threads (286) are formed in the exterior surface of the wall of the flexible elongate tubular member. A device as in Claim 2 further characterized in that the threads extend through the wall. A device as in any one of claims 1 to 3 further characterized in that the threads have a density ranging from 2.95 to 6 threads per mm (75 to 150 threads per inch). A device as in Claim 4 further characterized in that the threads have a density of approximately 4.3 threads per mm (108 threads per inch). A device as in any one of claims 1 to 5 further characterized in that approximately 1.5 to 5.0 threads are provided. A device as in any one of claims 1 to 6 further characterized in that the threads only extend partially through the wall of the tubular member. A device as in Claim 7 further characterized in that the threads are rectangular in cross section. A device as in Claim 1, further characterized in that a tip (296) is provided, said tip being formed of a cylindrical member having a wall defining a passage extending therethrough, the wall having an exterior surface, said tip having proximal and distal extremities, threads (297) formed on the proximal extremity of the tip securing the proximal extremity of the tip to the distal extremity of the coil spring, said tip having a recess (301) formed therein axially aligned with said passage and facing outwardly axially of the tip, said transducer (302) being disposed within said recess of the tip and means (304) securing the transducer (302) to the tip so that the transducer is disposed within the recess. A device as in Claim 9 further characterized in that the transducer (302) is provided with front and rear sides and wherein the front and rear sides are free to move and wherein the conductors extend through the passage to the tip. A device as in Claims 9 or 10 further characterized in that the threads of the tip have a density measuring from 2.95 to 6 threads per mm (75 to 150 threads per inch). A device as in any one of Claims 9 to 11 further characterized in that approximately 2.5 to 5.0 threads are provided in the tip. A device as in any one of Claims 9 to 12 further characterized in that the distal extremity of the coil spring is threaded into the threads of the tip. A device as in any one of Claims 1 to 13 further characterized in that said coil spring is formed of two separate coils (288,291) of two different materials, an intermediate joint (331) connecting the two coils, the intermediate joint comprising a cylindrical member having a wall provided with an exterior surface and opposite ends, threads formed in the opposite ends of the cylindrical member, one of said two coils being threaded into the threads on one end of said cylindrical member and the other of said two coils being threaded into the threads on the other end of said cylindrical member whereby the two separate coils and the cylindrical member are mechanically connected into a unitary assembly. A device as in Claim 14 further characterized in that the threads of the cylindrical member extend through the exterior surface of the wall. A device as in Claims 14 or 15 further characterized in that the threads of the cylindrical member have a density ranging from approximately 2.95 to 6 threads per mm (75 to 150 threads per inch).

Inventors: CHRISTIAN JEFFREY JACK, CORL PAUL DOUGLAS, SEGAL JEROME, CHRISTIAN, JEFFREY JACK, CORL, PAUL DOUGLAS, SEGAL, JEROME
Applicants: CARDIOMETRICS INC, CARDIOMETRICS, INC.
Application year: 1990
Main classification: A61B8
IPC codes: A61B8, A61M25, A61B17, G01N11