JP2016504928A - Self-cleaning intravascular catheter device and related methods - Google Patents

Abstract

An intravascular catheter having an elongate sheath, which surrounds an elongate flexible internal structure movable relative thereto, along with various exemplary embodiments of an irrigation device held by the internal structure. Such cleaning devices are operative to cause the cleaning liquid to flow from its source through the interior of the sheath in response to movement of the internal structure relative to the sheath, and thereafter to release the cleaning liquid from the sheath. In one embodiment thereof, the cleaning device includes an impeller structure disposed on the internal structure. In other embodiments, the cleaning structure includes an annular seal disposed on the inner structure with sliding and sealing engagement on the inner surface of the sheath.

Description

  Embodiments of the present disclosure relate generally to the field of medical devices, and more specifically to an apparatus and method for cleaning a catheter used in an intravascular blood vessel diagnostic method.

  In recent years, various techniques and systems have been developed to visualize the structure of vascular occlusions by using intravascular ultrasound (IVUS) imaging. IVUS technology is catheter-based and provides real-time cross-sectional images of arterial lumens and arterial walls. An IVUS catheter includes one or more ultrasound transducers at the distal end of the catheter, which can determine an image that includes cross-sectional information of the artery under examination. IVUS imaging allows visualization of the structure of the occlusion and, to varying degrees, the middle layer of the arterial wall and the boundary of the intima.

  A common type of IVUS imaging catheter system is typically a single transducer at the distal end of the catheter rotating at high speed (less than about 200 rpm) to produce a rapid series of 360-degree ultrasonic sweeps (a rapid series of 360-degree ultra sound sweeps). Such speed results in the generation of less than about 30 images per second, which effectively presents a real-time image of the diseased artery.

  The transducer is attached to the end of a drive shaft or cable that is connected to the motor drive at the proximal end of the catheter. The rotating transducer is housed in a sheath that does not interfere with the ultrasonic wave and protects the artery from the drive shaft that rotates at high speed. Thus, IVUS imaging (or “sensing”) catheters can be advanced to the area of occlusion using conventional angiography techniques and then the arterial wall middle layer and the intima and obstructions It can be manipulated to provide a real-time cross-sectional view of the vessel lumen in the containing arterial wall.

  Other types of catheter-based systems used to visualize internal structures of body parts are also placed on an elongate drive shaft or cable structure to implement a movable sensing / imaging element encased in a sheath. Known, including photoacoustics, optical coherence tomography, phased array / composite transducers, and spectroscopic systems. The performance of each of the catheter-based systems described above can be adversely affected by the presence of air inside its sheath portion adjacent to the inner movable sensing element. Bubbles may be present in the sheath prior to system operation or generated during system operation by rotation of a flexible drive shaft or cable located proximal to the sensing / imaging element. Sometimes. The presence of these bubbles tends to corrupt data or images that the system is designed to create in an undesirable way.

  A cleaning operation is usually performed to remove air in the entire sheath portion of the catheter structure from a particular system. As conventionally performed, the internal air removal operation is performed by pushing a cleaning solution, such as saline, distally through the entire length of the sheath to drain from the distal end of the opening. This cleaning technique utilized to date has its various known problems, limitations and disadvantages.

  For example, due to the considerable length of the sheath and the extremely small inner diameter (generally an effective length in the range of about 0.3 cm to about 20 cm and an inner diameter in the range of about 0.05 cm to about 0.1 cm) Pushing through the entire length from the proximal end of the sheath requires considerable pressure. Also required here is an attached one-way check valve and a removable syringe and additional parts in the form of a hose fitting, which undesirably increases the overall system cost. . The check valve also creates an obstruction near the handpiece portion of the system when the sensing / imaging structure is manually operated. In addition, measures are currently being taken to prevent air bubbles on the distal side and release them from the inside of the drive cable during system operation to reach the sensing / imaging structure and adversely affect its performance. There is no.

  As can be readily appreciated from the foregoing, there is a need for improved equipment and associated methods for cleaning medical catheters of the type generally described above. It is to this need that the present invention is primarily directed.

  In the practice of the principles of the invention, according to the first exemplary disclosed embodiment, is illustratively an IVUS catheter, or alternatively, for example, photoacoustic, optical coherence tomography, phased array / composite transducer or A medical sensing catheter that can be of other types, such as a spectroscopic type catheter, is provided.

  The catheter structure provides improved flushing, illustratively an elongated flexible sheath having a proximal end and an open distal end insertable into a region of the patient's body, and an interior of the sheath And an elongated flexible internal structure extending longitudinally therethrough and movable relative thereto. The internal structure has a distal end that has a sensing element disposed thereon and can be used to create diagnostic information for a region of the patient's body, typically an artery. Operates to generate a correct signal. Typically, the sensing element is an ultrasonic transducer.

  Between the inner structure and the sheath, a passage or a substantially barrier-free space surrounding the inner structure and extending along substantially the entire length of the inner structure received in the sheath Is placed. According to an important feature of the invention, an impeller structure is held by the internal structure, and in response to rotation of the internal structure with respect to the sheath, the cleaning liquid is supplied proximally from the supply source. Through the sheath and flow toward the support structure along the exterior of the support structure and then through a substantially barrier-free space where air is interposed between the support structure and the opposing inner surface of the sheath. It operates to cause the cleaning fluid to flow in a manner that prevents intervening. In an exemplary disclosed embodiment, the impeller structure may be a spiral surface groove formed externally on the distal end of the internal structure or an external impeller blade.

  When a catheter is typically placed in an artery, blood from the artery is used as a irrigation fluid and then a selective blood outlet formed in the sheath from a substantially barrier-free space. Can be returned to the artery. Alternatively, prior to use of the catheter in the body, the interior of the sheath can be cleaned in a similar manner using a non-blood cleaning solution, such as saline.

  According to another disclosed aspect of the invention, there is a method for flushing air from within a medical sensing catheter having a structure as described above, generally comprising: (1) the distal end of the internal structure relative to the sheath Configuring the distal end of the internal structure to pass cleaning fluid inwardly through the open distal end of the sheath and withdrawing from its source in response to rotation of the sheath; and (2) the By rotating the internal structure relative to the sheath, in a manner that prevents air from being interposed between the distal end of the internal structure and the opposing inner surface portion of the sheath, a cleaning liquid from a source is Thereafter, toward the distal end of the internal structure, it is passed through the sheath on the proximal side, along the exterior of the distal end of the internal structure, and then substantially on the proximal side. Fluidized through a barrier-free space Method is provided comprising that step. The catheter cleaning technique provided by this exemplary method can use blood or non-blood cleaning fluid.

  Using the catheter structure typically disclosed and the associated catheter application as provided by the present invention, the flow of cleaning fluid through the catheter sheath driven proximally causes the inner sheath to be adjacent to the support structure. Air is continually prevented from interposing undesirably between the transducer and the opposed inner surface portion of the sheath, and the air generated by rotation of the internal structure causes the transducer to hold the support structure A moving liquid barrier is formed to prevent movement to the distal side.

  In the second exemplary disclosed embodiment of the present invention, illustratively an IVUS catheter, or alternatively, for example, as a photoacoustic, optical coherence tomography, phased array / composite transducer or spectroscopic type catheter A medical sensing catheter device is provided that can be another type of medical sensing catheter. The catheter structure provides improved lavage, illustratively an elongate flexible sheath having a proximal end and an open distal end insertable into a region of the patient's body, and longitudinally through the interior of the sheath. An elongated flexible internal structure extending in a direction and movable relative thereto, said internal structure having a distal end, having a sensing element thereon and relative to a region of the patient's body Operates to generate signals that can be used to create diagnostic information. According to an important feature of the catheter device, an annular seal structure is held coaxially and externally by an internal structure proximal to the sensing element, and the seal structure slides on the inner surface of the sheath. Engageable and sealable and movable with the internal structure relative to the sheath.

  According to the structural aspect of the catheter device, the inner structure is moved proximally with respect to the sheath, and cleaning fluid is drawn through the distal end and proximally within the sheath, after which the inner structure Is moved distally with respect to the sheath and expelled received fluid and air into the outer end through the distal sheath end, thereby allowing the annular seal structure to move distally of the sheath. The conventional of allowing the end to be cleaned in a manner that releases undesirable air therefrom, thereby performing the necessary cleaning operations by pushing the cleaning liquid distally through the entire length of the sheath. Remove the need.

  In another structure of the second embodiment of the present invention, the impeller structure is provided on a portion of the internal structure that holds the sensing element, and the cleaning liquid is supplied to the sheath according to the rotation of the internal structure with respect to the sheath. Withdrawing proximally through the distal end and toward the sealing structure, thereby cleaning the distal end of the sheath without translating the internal structure relative to the sheath.

  In accordance with another disclosed aspect of the present invention, an elongated flexible sheath having a proximal end and an open distal end that is insertable into a region of a patient's body and extends longitudinally through the interior of the sheath. And an air irrigation method for use with a medical sensing catheter having an elongate flexible internal structure movable relative thereto, wherein the internal structure has a distal end, A method having a sensing element disposed thereon and operative to generate a signal that can be used to create diagnostic information for a region of a patient's body during movement of the internal structure relative to the sheath. Is done.

  From a broad perspective, the method includes flowing a large volume of cleaning fluid toward the sensing element and through the open distal end of the sheath, and then at least a portion of the large volume of cleaning fluid and Venting air that has already been placed inside the sheath through the distal end of the sheath to the outside. According to disclosed features of the method, such flow and release steps can include translating the internal structure through the sheath proximally and distally, respectively, and the sheath Respectively by rotating the internal structure.

  The catheter devices and associated cleaning methods typically disclosed herein provide a substantial improvement in the overall catheter cleaning operation. For example, if blood is utilized as a wash fluid, the need to use a second acoustic medium is eliminated, thereby desirably reducing the overall material cost of the diagnostic method and performing it distally. The irrigation procedure can also reduce the amount of particulates that can be introduced into the body. The catheter structures and associated methods typically disclosed herein further improve workflow and ease of use of the catheter by the operator, reduce the time required for the cleaning procedure, and eliminate air-related image disturbances. Improve the quality of diagnostic images.

1 is a very schematic partial cross-sectional view of an exemplary medical sensing catheter device embodying the principles of the present invention. It is a side view of other embodiment of the vibrator | oscillator support part of the catheter apparatus of FIG. It is a partial cutting schematic front view of 2nd embodiment of the medical sensing catheter apparatus of FIG. FIG. 4 is an enlarged cross-sectional view of a broken-line circle region “4” in FIG. 3. A typical catheter cleaning method embodying the principles of the present invention is depicted sequentially in schematic form. FIG. 6 is a schematic cross-sectional view of an enlarged scale of the distal end of another structure of the catheter device up to FIG. 7 shows another structure of the distal end of the inner catheter structure shown in FIG.

  Illustrated schematically in FIG. 1 is a medical sensing catheter device, typically a form of an intravascular catheter 10 that can be operatively inserted into a patient's artery 12 to perform a diagnostic arterial imaging procedure. Make. As a non-limiting example, the catheter 10 is a single rotatable transducer-type IVUS (intravascular ultrasound) catheter, but is instead placed on a long drive shaft or cable structure to the sheath. It can be one of various other types of catheter-based systems for use in visualizing the internal structure of a body part that implements a wrapped mobile sensing / imaging element, including but not limited to While not departing from the principles of the present invention, photoacoustic, optical coherence tomography and spectroscopic systems are included.

  Catheter 10 includes an elongated flexible tubular outer sheath 14 having an open distal end 16 and a proximal end 17. The effective length of the sheath 14 (ie, its length that can be operatively inserted into the patient) is much longer than its inner diameter. Illustratively, the effective sheath length ranges from about 0.3 cm to about 20 cm, and the sheath inner diameter ranges from about 0.05 cm to about 0.1 cm. Displaceably disposed within the sheath 14 is an elongated flexible internal structure 18 that supports a support structure 22 (commonly referred to as a “can”) that is secured to its distal end. An elongated flexible drive shaft or cable 20 having a sensing / imaging element, illustratively in the form of a single ultrasonic transducer 24, is provided.

  The proximal end 17 of the sheath and the proximal end of the drive shaft or cable 20 therein are operably connected to a suitable PIM (Patient Interface Module) of conventional construction that powers the transducer 24. And receiving an imaging signal therefrom. The PIM can also be operated to selectively drive translation and rotation of the internal structure 18 relative to the sheath 14, as indicated by arrows 26, 28 in FIG. 1, respectively. Alternatively, a separate drive structure can similarly drive the inner structure 18 relative to the sheath 14 or, if desired, translational and rotational movement of the inner structure 18 relative to the sheath 14 can be accomplished manually. be able to.

  As seen in FIG. 1, a substantially barrier-free space or passage 30 is disposed between the outer sheath 14 and the inner structure 18, which surrounds the inner structure 18 and is contained within the sheath 14. The inner structure 18 to be extended extends substantially along the entire length. According to a feature of the present invention, the impeller structure is externally disposed on the support structure 22, illustratively the support structure portion 22 of the flexible internal structure 18 on the proximal side of the transducer 24. It forms the form of a plurality of impeller blades 32 arranged above. Alternatively, as shown in FIG. 2, the impeller structure can include a suitable spiral groove 34 formed in the outer surface of the support structure 22 proximal to the transducer 24.

  As shown in FIG. 1, the inside of the sheath 14 can be easily cleaned by simply rotating the internal structure 18 relative to the sheath 14 as indicated by the arrow 28 by the catheter 10 housed in the artery 12. And release undesired air therein. Such rotation by impeller structure 32 (or possibly impeller structure 34 of FIG. 2) causes blood 36 from within artery 12 to flow inwardly through open distal end 16 of sheath 14 and support structure. Flow outwardly along 22 and then flow proximally through a substantially barrier-free annular passage 30. Thereby, the blood 36 flowing to the proximal side is used as a washing liquid to remove unwanted air from the inside of the sheath 14 and through the selective side wall blood outlet 38 formed in the sheath 14, the artery 12. You can move back in.

  This flow of cleaning liquid driven proximally through the sheath 14 causes the inner sheath air adjacent to the support structure 22 to be undesirably interposed between the transducer 24 and the corresponding inner surface portion of the sheath 14. It forms a moving liquid barrier that continuously prevents and prevents air generated by the fast rotating drive shaft or cable 20 from moving distally of the support structure 22.

  Shown schematically in FIGS. 3 and 4 is another embodiment 10a of the medical sensing catheter device 10 described above. The catheter 10a can be operatively inserted into the patient's artery 12 to perform a diagnostic arterial imaging procedure. As a non-limiting example, the catheter 10a is a single rotatable transducer type IVUS (intravascular ultrasound) catheter, but is instead placed on an elongate drive shaft structure and wrapped in a sheath. It can be one of various other types of catheter-based systems for use in visualizing the internal structure of a body part that implements a movable sensing / imaging element, which departs from the principles of the present invention Without exception, photoacoustics, optical coherence tomography, phased array / composite transducers and spectroscopic systems are included.

  Catheter 10a includes an elongate flexible tubular outer sheath 14a having an open distal end 16a and a proximal end 17a. The effective length of the sheath 14a (ie, its length that can be operatively inserted into the patient) is significantly greater than its inner diameter. Illustratively, the effective sheath length ranges from about 0.3 cm to about 20 cm, and the sheath inner diameter ranges from about 0.05 cm to about 0.1 cm. Displaceably disposed within the sheath 14a is an elongated flexible internal structure 18a that includes an elongated flexible drive shaft or cable 20a having a housing structure 22a secured to its distal end. , Illustratively supporting a sensing element in the form of a single ultrasonic transducer 24a.

  The proximal end 17 of the sheath 14a and the proximal end of the drive cable 20a therein are operably connected to a suitable PIM (Patient Interface Module) of conventional construction, which powers the transducer 24a. And receiving imaging signals therefrom. The PIM also operates to selectively drive translation and rotation of the internal structure 18a relative to the sheath 14a, as indicated by arrows 26a, 28a in FIG. 3, respectively. Alternatively, a separate drive structure can similarly drive the inner structure 18a relative to the sheath 14a, or such translation and rotational movement of the inner structure 18a relative to the sheath 14a can be manually performed, if desired. Can be realized.

  Referring to FIG. 4, according to an important aspect of the present invention, the catheter 10a also includes an annular sealing structure 40, which is supported on the housing portion 22a of the internal structure 18a proximally adjacent to the transducer 24a. And surround it coaxially. The seal structure 40 is slidably engaged with the inner surface of the sheath 14a in a sealed state, and can translate and rotate together with the inner structure 18a with respect to the sheath 14a. By way of non-limiting example, the seal structure 40 may include at least one metal ring (exemplarily a welded stainless steel ring), tape material such as PTFE tape material, or at least one overmolded on the internal structure 18. It can be of various types including an annular elastic sealing member.

  The unique provision of the seal structure 40 allows the sheath portion 14a of the catheter 10a to be cleaned, thereby pushing the cleaning solution distally through the entire length inside the sheath 14a. Air can be removed from its interior without the conventional problems, limitations and disadvantages associated with Examples of how such cleaning improvements can be achieved according to the present invention are shown sequentially in schematic form in FIGS.

  First, as shown in FIG. 5A, the housing structure 22a adjacent to the open distal end 16a facing down the sheath 14a allows the distal sheath end 16a to receive a large volume of cleaning fluid, typically saline, in a suitable container 44. Immerse in water 42. Thereafter, the internal structure 18a is raised from within the sheath 14a (as indicated by the arrow 46 in FIG. 5A) to the position of FIG. 5B. This elevation of the seal structure 40 creates a vacuum below the inner portion of the sheath 14a, thereby causing an amount 42a of saline 42 to rise above the inner portion of the sheath 14a. Pull up.

  Next, as shown in FIG. 5C, the distal sheath end 16a is turned upside down and the sheath 14 is struck (as indicated by arrow 48 in FIG. 5C) so that the sheath on the distal side of the seal structure 40 The air 50 in 14a is raised to the distal sheath end 16a. Finally, the internal structure 18a is pushed upward (as indicated by arrow 52 in FIG. 5D) towards the distal sheath end 16a, thereby causing saline 42a (with air 50 trapped therein) Release outward through the open distal sheath end 16a, thereby completing the catheter sheath cleaning operation.

  Using this improved cleaning technique requires that only the entire distal end of the sheath 14a need to be cleaned to prepare the catheter 10a for patient use, and that the overall cleaning operation is greatly increased. It should be noted that it needs to be simplified and speeded up. Furthermore, the equipment costs for realizing the necessary cleaning are desirably reduced. The efficiency of such a cleaning operation is also improved, which is due to the sealing structure 40 against bubbles generated by rapid operational rotation of the flexible drive cable 20a and reaching the distal side and hindering the imaging performance of the transducer 24a. Due to the fact that forms a barrier.

  FIG. 6 schematically illustrates an alternative cleaning method performed with an improved sheath and housing structure 14b, 22b embodying the principles of the present invention in an alternative catheter embodiment 10b. The sheath 14b shown in FIG. 6 is improved by forming a side wall vent opening 54 therein adjacent to the open distal end 16b. The housing 22b shown in FIG. 6 is improved by forming an impeller structure, typically a plurality of impeller blades 56, on the exterior thereof, between the vibrator 24b and the seal structure 40b. Be placed.

  Due to the distal end 16b of the sheath 14b submerged in the saline 42, the housing structure 22b adjacent to the distal end 16b and the seal structure 40 located proximal to the vent opening 54, the inner structure 18b becomes It is driven to rotate as indicated by arrow 58 without translation of the internal structure 18b relative to the sheath 14b. The rotating impeller structure 56 raises the portion 42b of the saline 42 inside the sheath 24b upward and releases it (along with air from below the seal structure 40) through the vent opening 54 to the outside. This completes the cleaning operation.

  FIG. 7 schematically shows another embodiment 22c of the housing structure 22b shown in FIG. An impeller structure formed from the outside on the housing structure 22c of FIG. 6 (which performs the same function as the blade 56 of FIG. 6) is defined by a spiral outer wall groove 60 formed on the outer surface of the housing structure 22c. In addition, the housing structure 22c in FIG. 7 is the same as the housing structure 22b in FIG. 6 except that the housing structure 22c is disposed between the vibrator 24c and the annular seal structure 40c.

  As can be appreciated, the present invention in the exemplary embodiment described above provides a substantial improvement in the overall catheter cleaning operation. For example, if blood is used as a wash fluid, the need to use a second acoustic medium is eliminated, thereby reducing the overall material cost of the diagnostic method and using a wash procedure for the distal side, Reduce the amount of microparticles that can be introduced into the body. The cleaning structure and method described above further improves the ease of use of the workflow and operator, reduces the time required for the cleaning procedure, and improves diagnostic image quality by eliminating air-related image disturbances. To do.

  The foregoing detailed description is to be clearly understood as merely given by way of illustration and example, and the spirit and scope of the present invention is limited only by the appended claims.

Claims (24)

A medical sensing catheter device,
An elongated flexible sheath having a proximal end and an open distal end insertable into a region of the patient's body;
An elongate flexible internal structure extending longitudinally through the interior of the sheath and movable relative to the sheath, the elongate flexible drive member having a distal end, secured to the distal end of the drive member And the internal structure having sensing elements that are held in the support structure and that are operative to generate signals that can be used to create diagnostic information about a region of the patient's body;
Retained by the internal structure, causing a flow of cleaning liquid from its source through the interior of the sheath in response to movement of the internal structure relative to the sheath, and thereafter causing the cleaning liquid to be released from the sheath A medical sensing catheter device comprising an operating cleaning device. The internal structure and the sheath are disposed therebetween to enclose the internal structure and provide a substantially barrier-free space extending along substantially the entire length of the internal structure housed within the sheath. Have
The cleaning device is held by an internal structure and prevents air from being interposed between the support structure and the opposed inner surface portion of the sheath, in response to rotation of the internal structure relative to the sheath, A cleaning fluid is flowed distally through the sheath toward the support structure, and flows along the exterior of the support structure, and then through a portion of the substantially barrier-free space. The medical sensing catheter device according to claim 1, comprising an impeller structure.   The medical sensing catheter device according to claim 2, wherein the impeller structure is disposed on the support structure.   The medical sensing catheter device according to claim 2, wherein the impeller structure includes a plurality of impeller blades.   The medical sensing catheter device according to claim 2, wherein the impeller structure includes a spiral groove arranged on the support structure from the outside.   The medical sensing catheter device according to claim 2, wherein the sensing element is an ultrasonic transducer.   The medical sensing catheter device according to claim 2, wherein a side wall liquid discharge port is formed in the sheath and is spaced apart from the support structure on the proximal side.   The medical sensing catheter device according to claim 2, wherein the medical sensing catheter device is an IVUS catheter.   The medical sensing catheter device according to claim 2, wherein the medical sensing catheter device has dimensions for use in a human artery.   The medical sensing catheter device of claim 2, wherein the sheath has an effective length in the range of about 0.3 cm to about 20 cm and an inner diameter in the range of about 0.05 cm to about 0.1 cm.   The cleaning device includes an annular seal structure that is coaxially held by the internal structure on the proximal side of the sensing element and held from the outside, and the annular seal structure is slidable on the inner surface of the sheath and is in a sealed state The medical sensing catheter device according to claim 1, wherein the medical sensing catheter device is engaged with the sheath and is movable with the internal structure with respect to the sheath.   The medical sensing catheter device of claim 11, wherein the sensing element includes an ultrasonic transmitter.   The medical sensing catheter device according to claim 11, wherein the seal structure includes at least one metal ring member.   The medical sensing catheter device of claim 13, wherein the at least one metal ring member is a welded stainless steel material.   The medical sensing catheter device according to claim 11, wherein the seal structure includes at least one seal member overmolded on the internal structure.   The medical sensing catheter device of claim 11, wherein the seal structure comprises a tape material wound around the internal structure.   The medical sensing catheter device according to claim 16, wherein the tape material is a PTFE tape material.   The medical sensing catheter device according to claim 11, wherein the medical sensing catheter device comprises an IVUS catheter.   By moving the internal structure proximally, cleaning liquid is continuously drawn distally within the sheath, and air is drawn into the drawn portion of the cleaning liquid adjacent to the open distal end of the sheath. The sheath extending distally from the seal structure by causing the inner structure to move distally relative to the sheath and then releasing air through its distal end The medical sensing catheter device of claim 11, wherein the annular seal structure is configured and operative to facilitate the removal of air from a portion of the interior of the device.   An impeller structure is retained on the internal structure distal to the seal structure and fluid is passed proximally to the sheath during rotation of the internal structure relative to the sheath. 12. The medical sensing catheter device of claim 11 operative to retract toward.   21. The medical sensing catheter device according to claim 20, wherein the impeller structure includes a spiral blade structure disposed on the internal structure from the outside.   21. The medical sensing catheter device of claim 20, wherein the impeller structure comprises a helical external groove formed on the internal structure. The medical sensing catheter device is further arranged to extend through the sheath and the impeller structure to form a drain through which fluid is drawn proximally toward the seal structure through the sheath. With vent opening,
21. The medical device of claim 20, wherein the distal portion of the sheath can be cleaned by immersing the distal end of the sheath in a cleaning solution and rotating the internal structure relative to the sheath. Sensing catheter device.   12. The medical sensing catheter device of claim 11, wherein the sheath has an effective length in the range of about 0.3 cm to about 20 cm and an inner diameter in the range of about 0.05 cm to about 0.1 cm.

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