Anti-recoil catheter

ES 2 245 679 T3

DESCRIPTION

Anti-reverse catheter.

Field of the invention

The present invention relates to catheters used during diagnostic and / or operative procedures to deliver fluids to a patient. The present invention is particularly concerned with an angiographic catheter having controlled fluid flow properties for delivering fluids, such as contrast media, in a human or animal body. Background of the invention

Catheters are commonly used in the diagnosis and treatment of various medical conditions and progress has been made in catheter designs and materials particularly well suited for intravascular procedures and intravascular therapies. A conventional catheter includes a small, elongated tube made of flexible, biocompatible materials that allow the catheter to be easily manipulated through body conduits and vascular structures. During an angiographic procedure, the distal end of the catheter is typically inserted into the body via small incisions in the groin or upper arm area, and guided through anatomical conduits and / or blood vessels to a target site using guide wires. and associated imaging techniques. The proximal end is then connected to the device to perform the desired procedure. One such device is an angiographic injector such as the injector described in US Patent Application Serial No. 08 / 957,228 and / or the injector described in US Patent No. 5,800,397, the which are commonly assigned to the owner of the present application.

An example of a procedure that uses a catheter is angiography. Angiography is a procedure used to specifically visualize, diagnose, and treat abnormalities in the heart or vascular structures. During angiography, a doctor inserts a catheter and injects contrast material through the catheter into a vein or artery of a patient. The area of ​​the patient's body injected with the contrast material is visualized using X-ray energy or magnetic fields (as used in magnetic resonance imaging), and the resulting image is recorded and / or displayed on a monitor. The images can be used for many purposes, including diagnostic activities as well as operative procedures such as angioplasty, in which a balloon is inserted into a vascular system and inflated to open a stricture.

During the injection procedure, fluid typically flows from the open distal end of the catheter tip. However, the fluid dynamics associated with some catheter designs frequently cause the catheter to be pushed back or back as a result of the velocity of the fluid as it exits the distal tip. Indeed, the recoil force of the catheter is directly proportional to the speed of the fluid at the tip.

Such undesirable recoil movement is particularly critical when using a small catheter size, for example less than about 1.33mm, since these catheters experience particularly high fluid exit velocities due to flow requirements in an angiographic procedure. typical. However, even larger catheters can be prone to greater recoil if the fluid flowing from the tip is of sufficient velocity. Overall, however, smaller angiographic catheters are more prone to severe whiplash and kickback at the start of an injection than larger catheters. This, in part, is due to the structural characteristics of the catheters. In particular, as the diameter of the catheter shaft decreases, the bending force is reduced by the diameter at the third power. Thus, a reduction in shaft diameter from 2 to 1.33mm provides a four-fold reduction in bending force given the same load and distance at which the load is applied.

Catheter designs incorporating valves or openings located along the distal portion of the catheter wall have been considered in an attempt to facilitate better control of fluid flow. An example of such a device can be found in US Patent No. 5,250,034, which describes a pressure sensitive valve catheter. The catheter is formed of a relatively poor compliant material, such as nylon, to prevent the side walls of the catheter from expanding at the high internal fluid pressures. The slits formed in the catheter wall act as pressure sensitive valves to allow fluid to escape into the internal lumen of the catheter while preventing material from entering the catheter lumen via the slits. The catheter also includes a distal end hole that can be sealed with a ball of occlusion located on a guidewire, thereby causing all fluid to flow from the slits. Alternatively, when the occlusion ball is not seated in the end hole, fluid and guidewire can flow out of the end hole.

Another example can be found in US Patent No. 5,807,349, which describes a catheter that has a valve mechanism to allow the infusion or aspiration of fluids between the catheter and the vessel in which the tube is positioned. catheter. The valve is located at the distal end of the catheter and is preferably in a plane that is oriented at an angle to the longitudinal axis of the catheter.

The above-described catheters used during angiographic procedures (and other similar devices not specifically described) offer many advantages in controlling fluid flow. However, it has been found that these catheter designs do not adequately address problems with catheter recoil within the vessel or body cavity. Furthermore, these and other prior art catheter valve mechanisms can still suffer from erratic valve openings and closings that can trigger recoil of the catheter. Additionally, neither of these designs nor any of the other designs known to the inventors appear to address the particularly critical problem of recoil with small catheters (eg, smaller than about 1.33mm) used in angiographic procedures.

In this regard, it is also important to note that there is a continuing need and desire in the medical field to reduce trauma to patients who are undergoing invasive therapies. In the context of catheter placement, this desire has led to consideration of how to reduce trauma to the

ES 2 245 679 T3 patient during the placement and removal of the catheter used in the intervention.

In current techniques, the catheters that are used require a significant incision in the patient so that there is considerable pain faced by the patient and considerable care is required to control the wound by the physician. Certainly, the wound created by such procedures requires the physician to apply a significant bandage or other device to contain the wound (eg, a product known as Percutaneous Vascular Surgery's Perclose) to ensure proper treatment and closure of the wound. Additionally, such a wound requires significant time for proper healing to occur.

As a result, there is a growing desire to use catheters of smaller sizes in such interventional therapies in order to make the intervention as minimally invasive as possible. Such small catheters require a significantly smaller incision, thereby reducing trauma and achieving faster healing. However, as previously mentioned, such smaller catheters are typically accompanied by disadvantages such as undesirable flow characteristics (eg, recoil).

In view of the foregoing, although currently available catheters appear well accepted by the medical community and generally function as required, it is desirable to have a catheter with more controlled fluid flow characteristics and less invasive attributes. In particular, it is desirable to have a small diameter catheter that allows fluid forces to be managed to stabilize the distal tip over a wide range of injection parameters. It is also desirable that the catheter tip does not recede or recede substantially little in a small diameter catheter during high volume injections, such as those associated with ventricular or coronary angiography. Furthermore, it is desirable to have a "universal" catheter that can be used for a variety of surgical procedures and that reduces trauma inflicted on the patient. The concept of a "universal" catheter, as applied to the present invention, is similar to a muzzle brake device that attaches to the outer cylinder of any firearm, and works to reduce the recoil of the firearm while simultaneously which maintains the accuracy of the download. Therefore, as with the muzzle brake device, it is desirable that the present invention accommodate a variety of catheter designs and reduce catheter movement during various medical procedures. Objects and summary of the invention

In view of the foregoing, it is an object of the present invention to provide a catheter assembly that addresses the obstacles and disadvantages associated with the current problem of catheter recoil caused by undesirable fluid forces during an injection procedure.

A further object of the present invention is to provide a small diameter catheter assembly that allows fluid forces to be managed to stabilize the distal tip over a wider range of injection parameters.

A further object of the present invention is to provide a catheter that is less invasive and reduces trauma to the patient.

These and other objects not specifically listed herein are considered to be addressed by the present invention as defined in the claims. Preferably it contemplates a catheter assembly comprising a hub section located at a proximal end of the catheter, a shaft section attached to the distal end of the hub, a stem section that is attached to the distal end of the shaft, and a distal tip section. attached to the distal end of the stem section. In addition, the catheter assembly also includes a plurality of openings located in the stem and tip sections that provide proper balance of fluid forces as fluid exits the catheter openings.

The catheter is for use in performing a medical procedure and comprises an elongated tubular structure having a proximal end and a distal end. The tubular structure is configured to be no larger than about 1.33mm in size and is designed to facilitate fluid flow rates in the range of about 0 to 40ml / s, and pressures up to 8.27.10⁶ Pa, without causing failure of the tubular structure. In addition, the distal end of the catheter includes an elastic limiter and a plurality of openings arranged so that the forces resulting from fluid flow are substantially balanced during the performance of the medical procedure. The spring limiter is also configured to allow insertion of a guidewire greater than 0.508 mm in diameter through the distal end of the limiter.

A further object is to provide a method of performing a medical procedure by providing a catheter having a proximal end and a distal end, and having a size no greater than about 1.33mm, and introducing the catheter into a patient. The method also comprises introducing a fluid into the patient at a flow rate in the range of about 0 to 40 ml / s, without causing failure of the catheter. Since the flow rate is limited to the maximum allowable pressure based on the size of the catheter, a 1.33 mm catheter will allow a maximum flow rate of 15 ml / s at 8.27.10⁶ Pa. An ultimate goal of the method includes balancing the forces acting on the catheter resulting from the introduction of fluid flow by variably restricting fluid flow at the distal end of the catheter according to flow rate, and directing the fluid out of a plurality of openings in a wall of the catheter.

Brief description of the drawings

Other characteristics and advantages of the present invention will be seen as the following description of the particular embodiments progresses in conjunction with the drawings, in which:

fig. 1 is a side perspective view of a catheter assembly in accordance with a preferred embodiment of the present invention;

fig. 2 is a perspective view of a portion of a catheter assembly in accordance with a preferred embodiment of the present invention;

fig. 3 is a cross-sectional view of a catheter assembly in accordance with a preferred embodiment of the present invention;

fig. 4 is a cross-sectional end view of a catheter assembly in accordance with a preferred embodiment of the present invention;

fig. 5 is a cross-sectional view of a

ES 2 245 679 T3 guide wire inserted into a catheter assembly;

fig. 6 is a cross-sectional view of a catheter assembly in accordance with a preferred embodiment of the present invention;

fig. 7 is a cross-sectional view of a catheter assembly according to a preferred embodiment of the present invention;

fig. 8a is a perspective view of a catheter assembly according to a preferred embodiment of the present invention;

fig. 8b is a perspective view of a catheter assembly according to a preferred embodiment of the present invention;

fig. 9 is a perspective view of a trial piece for a catheter assembly;

fig. 10 is a cross-sectional view of a test piece for a catheter assembly.

fig. 11 is a perspective view of a test piece for a catheter assembly.

fig. 12 is a graph illustrating catheter movement as tested on a catheter assembly in accordance with a preferred embodiment of the present invention; and fig. 13 is a graph illustrating fluid reflux as tested in a catheter assembly in accordance with a preferred embodiment of the present invention. Detailed description of the invention

Referring to Figure 1, one embodiment of a conventional catheter 10 such as a diagnostic catheter used during angiography or other procedures, in accordance with the present invention includes four major sections including a hub 12, shaft 14, stem 16, and tip 18. The entire length of the catheter assembly 10, which includes the four major sections, has a maximum outer diameter or outer diameter of approximately 1 1/3 mm. As discussed in greater detail below, the tip configuration in combination with the small diameter size of the catheter results in a catheter that has improved management of fluid forces that better stabilize the distal tip 20 of catheter 10 on a wide range of injection parameters.

As shown in Figure 1, the majority of catheter 10 comprises shaft portion 14 which includes a central conduit 22, a distal end 24, and a proximal end 26. Conduit 22 through shaft 14 communicates with tip 18 for the passage of devices or fluids. Attached to proximal end 26 of shaft 14 is hub 12. Hub 12 provides a standard interface for syringes, injectors, and other similar devices and provides access to central conduit 22 of shaft 14. The stem section 16 of the catheter assembly includes a distal end 28 and a proximal end 30. The proximal end 30 of the stem section 16 is attached to the distal end 24 of the shaft 14 and includes a central conduit 32 connected to the conduit 22 of the shaft. Located at the distal end 28 of stem 16 is the tip 18 of the catheter.

In one embodiment of the catheter, hub 12 is frustroconical in shape with an associated cylindrical portion 34 located at the smallest diameter, distal end of the hub. Other appropriate geometries of hub 12, such as tubular, frusto-spherical, funnel-shaped, or the like, may also be used with the device of the present invention. In general, however, the design of the hub as a whole is such that 4 allows the hub to be compatible with standard luer specifications.

Proximal end 36 of hub 12 has a preferred internal diameter of approximately 4.2mm. However, the proximal diameter 36 of hub 12 can range from 1.0 to 4.2 mm, or any suitable size that allows a syringe or similar device to fit within hub 12 of catheter 16. In a preferred embodiment, the distal end 38 of hub 12 has an internal diameter in the range of 0.9 to 1.1 mm, which forms a hub conduit 40 that mates in collaborative relationship with conduit 22 of shaft 14 of the catheter.

As shown in Figure 1, the catheter assembly 10 further includes a shaft 14 that extends along the longitudinal axis of the catheter. The bore / conduit 22 of shaft 14 has a manufacturing specification of 1.0 ± 0.05mm. In a preferred embodiment, shaft 14 comprises a multilayer tube having a first inner plastic layer extruded from a polymeric material, such as Pebax.^® (manufactured by Autochem) that has a durometer of approximately 50-60 D. Other polymer materials such as urethane or nylon-based may also be used, as long as these materials have a Shore hardness in the range of approximately 50 durometer -60 D.

The second layer of shaft 14 comprises a metallic or polymer-based material, such as stainless steel cladding, carbon fibers, extruded polymer tubing, or similar materials that have various configurations capable of withstanding pressures resulting from torque or other manipulations. of the shaft, this is applied by a conventional manufacturing process and covers the first layer of polymeric material. Alternatively, shaft 14 can also be made of plastic having radiopaque fillers, typically bismuth or barium chemical salts or elements such as platinum or tungsten. The second layer is circumscribed and extends along axis 14 to provide sufficient rigidity and structural support to catheter 10. The third or outer layer comprises a polymeric material similar to that of the first layer and is extruded, or applied by other suitable means, over the coating layer. The material configuration of shaft 14 provides structural strength and increases rotational stiffness for placement of catheter 10 at the target site.

Referring to FIG. 1, section 16 of the catheter shaft 10 comprises a solid plastic tube with a central conduit 32 that mates with or connects to the distal end 24 of conduit 22 of the shaft. Stem 16 and shaft 14 are joined together via bonding by heating, welding, or other similar processes. In a preferred embodiment of the invention, the stem section 16 has a manufacturing specification of 1.0 ± 0.05 mm for its internal diameter and 25.0 ± 2.0 mm for its longitudinal length. The particular length of section 16 of catheter stem 10 may vary depending on the type of procedure to be performed, user technique, patient parameters, and the like.

The stem section 16 is made of a material that is softer than the shaft 14 material. In a preferred embodiment, the stem 16 material is made of approximately a 40-50 D durometer material from Pebax.^® loaded with a material

ES 2 245 679 T3 radiopaque. Such radiopaque materials include chemical salts of barium or bismuth or pure elements such as platinum or tungsten or other similar materials. Such radiopaque materials can be incorporated into the stem section, bonded or embedded within the stem section in a wire or ring configuration. The softer material of the section stem 16, together with its particular geometric shape, allows the stem section 16 to conform to the area of ​​the vessel or body organ being catheterized.

As shown in FIG. 1, section 18 of the distal tip of catheter 10 is attached to the distal end 28 of section 16 of the stem. In a preferred embodiment, the tip section 18 is approximately 3.0 ± 1.0 mm in length and has a completely spherical radius of curvature, similar to a rounded shape. Preferably, the tip 18 of the rounded end is made of approximately 30-40 D Pebax durometer.^® loaded with a radiopaque material. Such radiopaque materials include chemical salts of barium or bismuth or pure elements such as platinum or tungsten and other similar materials. Such radiopaque materials can be incorporated into the stem section, bonded or embedded in the stem section in a wire or ring configuration. The preferred material is Pebax^® loaded with bismuth trioxide due to its superior biocompatibility, mechanical properties, and radiopacity characteristics.

Alternatively, tip section 18 may comprise various other materials, such as a soft plastic as long as the characteristics of the material are such as to reduce injury or trauma to the interior of the vascular organ or system as catheter 10 is moved through. of the system. In general, the material of the tip section 18 should be elastic enough to allow expansion to accommodate guidewires having outer diameters that are larger than the inner conduit of the restrictor. In addition, the material of the tip section 18 should also allow expansion of the restrictor in response to increased fluid pressure during an injection procedure.

The size of the catheter is small, in the range of about 1 1/3 mm. In normal procedures, such small catheters are required to allow practical flow rates of up to ml / s along with the requirement for pressure variations without failure in the catheter structure. As such, the catheter materials must have appropriate strength to accommodate these operating parameters.

Additional structural features of the stem 16 and tip 18 sections of the catheter assembly of the present invention are shown in Figures 2 and 3. One or more openings 42, such as holes, slits, slots, valves, or other similar types of cavities, are formed in the wall of the stem section near the distal end 20 of catheter 10. The openings 42 form a conduit (s) in the wall of stem section 16 that interconnects the inner conduit of catheter 10 to the outer surface of the catheter body. As such, fluid flowing through the inner conduit of catheter 10 can easily exit catheter 10 via the conduit (s).

As illustrated in Figure 3, openings 42 in stem section 16 are angled toward proximal end 36 or hub 12 of catheter 10. This particular angled configuration causes fluid to flow out of the inner conduit of catheter 10 to flow in a direction opposite to the fluid stream. Consequently, the resulting direction and magnitude of fluid flow as it exits catheter 10 supplies the forces that push catheter 10 in a distal or forward direction. Furthermore, by appropriately spacing openings 42 along section 16 of catheter shaft 10, the radial or lateral forces generated by the backward movement of fluid as it exits catheter 10 are ideally balanced. As a result, the configuration of the catheter shaft section 16 substantially reduces or altogether prevents a kickback, whiplash movement, or excessive movement of the tip 18 during an injection.

Referring to Figures 2, 3 and 4, the soft material of tip section 18 is also constructed to include a small aperture or limiter 44 located at the distal end 20 of tip 18. In a preferred embodiment, the diameter of the limiter 44 is approximately 0.305 ± 0.05 mm. Alternatively, the restrictor 44 may have any structure or design feature formed in or attached to the catheter 10. The particular placement and shape / design of restrictor 44 may vary as long as its overall configuration resists fluid flow in the forward direction, thereby forcing fluid to flow through openings located along section 16. of the stem of the catheter body and that allows good pressure measurement.

As shown in FIG. 5, the limiter 44 is also designed to allow the passage of a guide wire 46 through the distal end 20 of the tip 18 via expansion and elastic deformation of the tip material. When guidewire 46 is inserted through limiter 44 of tip section 18, any significant amounts of fluid flow through tip 18 are limited and reoriented through openings 42 of the tip. stem section 16. However, when using a smaller guide wire. such as an angioplasty guide wire having a diameter of approximately 0.254-0.356 mm, fluid flow through tip 18 can be increased.

Typically, during use of the device, however, fluid is not introduced into the inner conduit of catheter 10 when guidewire 46 is positioned at tip 18 since the purpose of guidewire 46 is to guide or orient catheter 10 to the target site and does not function as a flow inhibitor. After catheter 10 is positioned in the body, the fluid is then injected into the lumen of catheter 10 for delivery to the target site.

Alternatively when guidewire 46 is withdrawn from catheter 10, fluid flows through openings 42 in stem section 16 and restrictor 44 in tip section 18. The small size of the restrictor 44 and the elasticity of the tip section 18 function to provide a controlled amount of fluid flow exiting the distal end 20 of the tip 18. The elasticity of the tip 18 allows a variable fluid force restriction that is proportional to the flow rate of the fluid. For example, as fluid flow increases, so does the size of the restrictor 44 opening. As such, there is a relatively linear relationship between flow

ES 2 245 679 T3 of fluid and the size of the limiter 44, similar to the elastic response of a spring.

In one embodiment, the flexibility of the tip section 18 can be selected such that the diameter of the restrictor 44 increases in size under certain flow conditions. In a preferred embodiment, the tip section 18 has a durometer of about 30-40 D and a size of the limiter 44 of about 0.305 ± 0.05. This combination appears to be effective in obtaining the desired expansion of the restrictor 44 under normal operating flow ranges. For typical procedures, such as a coronary procedure, the flow rate in a small catheter, for example less than 1 1/3 mm, is less than about 20 ml. Such flow often leads to peak pressures of about 8.27.10⁶ Pa in such small catheters.

By redirecting the flow of fluid from the restrictor 44 to the openings 42 of the catheter 10 of the present invention, the backward force exerted on the shaft 14 of the catheter is substantially reduced. In particular, forces generated by fluid flow from angled openings 42 located along stem section 16 neutralize backward recoil forces created by fluid flowing from restrictor 44. As such, the particular configuration of the openings 42 along with the unique design of the limiter 44 appears to provide substantial cancellation of the fluid force vectors, thereby avoiding unwanted, excessive movement of the catheter 10.

The catheter 10 of the present invention also offers many advantages and safety features. For example, openings 42 in stem section 16 reduce or eliminate the occurrence of jet lesions at the distal end 20 of catheter 10. This feature not only prevents possible trauma to vessel structures and tissues from fluid forces, but it also minimizes the potential for vessel wall staining when contrast material is used during an injection procedure.

Furthermore, the openings 42 located along the catheter body also act as pressure relief valves when the distal tip 18 of the catheter 10 accidentally rests against the wall of a vessel. As such, the fluid forces are redistributed and allowed to flow through the openings 42 so that the injection procedure can continue safely. Furthermore, the pressure relief feature of the present invention also allows a device operator to continue to obtain accurate pressure measurements when one or more catheter openings 42, 44 become clogged without having to terminate the procedure. As a result, the device of the present invention also increases user comfort.

Various embodiments of the device of the present invention illustrating the dimensions, number, and placement of openings 42 along section 16 of catheter shaft 10 are shown in Figures 3, 6, and 7. As shown in Figure 3 , the catheter assembly includes a total of twelve openings 42 that are equally spaced in three rows of four openings along the longitudinal axis 48 of stem section 16. Each opening 42 is approximately 0.3302 mm in diameter and comprises a proximal end 50 and a distal end 52. In one embodiment of the present invention, the angle A of each opening 42 is approximately 30 ° (+ 0 °, -5 °) from the longitudinal axis 48 of the catheter body and is formed toward the proximal end 36 or hub 12 of the catheter 10. Alternatively, the angle A of each opening 42 may range from about 10 ° to 50 °, based on the desired fluid flow characteristics and type of the catheter.

The openings 42 are manufactured via a punching process; however, other manufacturing methods can be used. The elliptical or elongated / angled appearance of the apertures 42 results from a circular aperture that is punched out or formed in an angled plane. As such, if the apertures 42 were viewed in the true position, ie perpendicular to the plane of the apertures 42, the apertures would appear to be circular in shape.

Referring to Figure 3, the first row 54 of openings 42 includes four circumferentially spaced conduits that are located approximately 4.24 ± 0.2 mm from distal end 20 of tip 18 to distal end 52 of each opening 42. Likewise, the proximal ends 50 of the second row 56 of the openings 42 are located approximately 5.76 ± 0.2 mm from the distal end 52 of each opening 42 in the first row 54. In addition, the third row 58 of openings 42 are spaced approximately 7.79 ± 0.2 mm from their ends 50 near their distal end 52 of each opening 42 in the first row. This particular longitudinal spacing and circumferential alignment of the openings 42 in the stem section 16 in combination with the design of the restrictor 44 in the tip 18 provides proper balance of the flow forces generated by the fluid flow, thereby substantially eliminating the occurrence of distal tip 18 movement, such as recoil, when used in the coronary artery, or lateral movement, when used in the ventricle or aorta.

In a preferred embodiment of the present invention, a total of eight openings 42 are located in section 16 of the catheter shaft 10. As shown in Figure 6, the spacing and alignment of the openings 42 in this embodiment of the invention are Similar to the previous embodiment except that the third row 58 of the openings 42 has been removed. In yet another embodiment, shown in Figure 7, the second row 56 and third row 58 of openings 42 have been removed, thereby leaving a total of four equally spaced openings 42 in section 16 of catheter shaft 10.

The catheter of the present invention can include various numbers and configurations or shapes of openings 42,44. In one embodiment, the catheter can also include a diffuser that diffuses fluid flow through the openings 42. As shown in Figures 8a and 8b, the diffuser can be a screen positioned over the openings 42 or, alternatively, it can be a series of small holes or openings that cumulatively form an opening 42. However, the location, size and quantity of the openings 42,44 should be such that the fluid flow forces are substantially balanced, thereby resulting in a zero net fluid flow force.

Although catheter 10 has been described to include four major sections, it should be understood that this device also includes fewer than four and / or

ES 2 245 679 T3 more than four sections. For example, catheter 10 may be composed of a single section that has various materials, designs, and structural features throughout its length. The specific material, design, and structural features of catheter 10 are individually configured to facilitate the medical environment in which catheter 10 is to be used. Therefore, when used during a ventricular angiographic procedure, catheter 10 also includes several sections and a ring-shaped end with a series of openings. In contrast, when used during a coronary angiography procedure, catheter 10 would comprise various sections and have a specific distal end shape, such as a left Judkins catheter.

Alternatively, catheter 10 may be structured so that each row of openings is located over a separate section from catheter 10. In addition, catheter 10 may also comprise additional sections that have unique material, design, or structural features specifically tailored for facilitate the particular procedures to be carried out with the device of the present invention. As such, it should be understood that the invention is not limited to the embodiments described above. In particular, with respect to the number, size, and placement of openings 42 in stem 16 and sections 18 of catheter tip 10, the design features of openings 42 include those embodiments that provide the proper balance of lateral forces. and distals created by respectively the back and forth movement of the fluid as it flows from the inner conduit and exits the openings 42 of the catheter body.

Test pieces and methods

Various types of angiography procedures using various embodiments of the catheter were simulated. The tests were specifically designed to simulate an injection procedure and determine the effects of fluid flow forces on catheter movement during an injection procedure. In addition, the test results were also used to evaluate the various catheter design parameters including, but not limited to, the number of openings, tip limiter configuration, and diameter of the openings. Due to the sensitivity of the tests and significant environmental mechanical differences between the live injection procedure and the simulated injection procedure, the results obtained from the simulation represent a worst-case scenario of fluid flow effects on the movement of the catheter. However, the data from these tests is extremely valuable as it highlights the importance of properly balancing catheter parameters to substantially reduce or eliminate whiplash and / or recoil movements of the catheter body during injection procedures.

Test pieces and specially designed test procedures were created to simulate a typical angiography injection and measure catheter movement during the injection procedure. As shown in Figure 9, a trial piece 60 consists of a transparent or semi-transparent box, such as one made of acrylic, that has at least two chambers 62, 64. Both chambers are filled with water or a similar fluid to approximate the internal area and pressures of a vascular body or structure. It is preferred that the trial part 60, or at least a portion of the trial part 60, is transparent and filled with a virtually transparent fluid to allow a device operator to visualize the flow of fluid in the part 60 during a procedure. injection.

As shown in Figure 10, a through hole 66 located centrally near the lower half of a separating wall 68 is dimensioned to simulate the hole in a vascular structure through which the catheter 10 is to be inserted. the top 68 of the trial piece and the location of the through hole 66 represents a worst-case scenario of catheter placement in a vascular structure. Typically, when used on a human subject, various lengths or sections of catheter 10 are supported by surrounding tissue structures, thereby limiting movement of the catheter. In contrast, when worn on the trial piece 60 as shown in FIG. 10, the catheter 10 is suspended in an unsupported manner from the top 68 of the piece 60. As a result, the effects of fluid flow on catheter movement are more pronounced when the trial piece 60 of the present invention is used.

To determine the amount of reflux generated by fluid flowing from openings 42,44 of catheter 10, catheter 10 is tested at two positions in test piece 60. In a first position, the distal end 20 of the catheter tip 18 is contained in the through hole 66 of the separating wall 68. A stained fluid is injected at a specific flow rate into proximal end 36 of catheter 10 that simulates an angiographic injection procedure. The force of the stained fluid flowing from the restrictor 44 and the apertures 42 and incident on the walls of the through hole 66 causes some of the stained fluid to flow back from the first chamber 62 into the second chamber 64. A visual comparison of the density of the staining between the first and second chambers 62,64 is performed using a ten point scoring scale. For example, a first chamber 62 scores nine and a second chamber 64 scores one indicates relatively small fluid backflow, compared to a first chamber 62 scores two and a second chamber 64 scores eight.

To further evaluate the effects of fluid backflow, the catheter 10 is also tested in a second position in which the distal end 20 of the catheter tip 18 extends beyond the through hole 66 of the separating wall 68. When catheter 10 is located in the second position, limiter 44 is fully contained in first chamber 64 of trial piece 60. As a result, only the fluid flow forces generated by the stained fluid flowing from the openings 42 of the catheter 10 and impinged on the walls of the through hole 66 cause some part of the stained fluid to flow back into the second chamber 64. As before, a visual comparison and grading of the dye density is performed between the first and second chambers 62, 64 of the test piece 60 using a ten point rating scale.

A second test piece 70 is used to evaluate the amount of catheter movement caused by fluid flow during an injection procedure is shown in Figure 11. The second piece

ES 2 245 679 T3 test comprises a transparent or semi-transparent box, such as one made of acrylic, having at least one chamber 72. As with the first test piece 60, the chamber 72 of the second test piece 70 is filled. with water or a similar fluid to approximately the internal area and at the pressures of a vascular body or structure. It is preferred that the trial part 70, or at least a portion of the trial part 70, is transparent and filled with a virtually transparent fluid to allow a device operator to observe the movement of the catheter in the part 70 during a procedure. injection.

As shown in FIG. 10, a grid configuration 74 is located on a front wall 76 of trial piece 70. The size of each square 78 of grid 74 is approximately 5mm X 5mm, although other frame sizes may also be used depending on the type of test procedure to be performed and the measurement accuracy of the test desired. The grid configuration 74 is used as a scale to measure catheter movement during a stimulation of the injection procedure.

During use of the trial piece 70, a catheter 10 is clamped or suspended from one of several holes 80, located on the top wall 82 of the trial piece 70, such that the distal tip 18 of the catheter 10 is positioned in the area of ​​the grid pattern 74. If the section 18 of the tip of the catheter 10 is curved, the lateral and backward movement of the catheter 10 can be measured using the test piece 70 of the present invention. For example, positioning catheter 10 so that its tip section 18 is in a plane parallel to grid configuration 74 allows an operator to measure catheter recoil. In addition, the lateral movement of catheter 10 can also be measured by simply rotating catheter 10 90 ° along its longitudinal axis so that its tip section 18 is relatively perpendicular to the grid configuration 74 of part 70. test.

To measure catheter recoil, fluid is injected at a specific flow rate into proximal end 36 of catheter 10 that simulates an angiographic injection procedure. As fluid flows from restrictor 44 and openings 42 from catheter 10, an operator measures the amount of movement of the catheter due to fluid flow forces using the grid configuration 74 of trial piece 70. It should be noted that the same procedure can also be used to measure the lateral movement of catheter 10, provided that catheter 10 is properly positioned in test piece 70.

Test results

The tests were performed using the test pieces 60, 70 described above and the catheter prototypes. As shown in Figure 12, the tests used two prototype catheters 10. A catheter design 10 included eight angled openings 42 located along section 16 of the stem and a restrictor formed in section 18 of the distal tip. The design of the other catheter 10 included 12 angled openings and a restrictor. The 90 ° through hole of each opening 42 comprised a diameter of approximately 0.33mm. Also, the diameter of the limiter 44 was approximately 0.305mm.

During the first set of experiments, 10 ml of fluid was injected at a flow rate of approximately 2 ml / s into catheter 10 which has eight angled openings. As shown in Figure 11, during the first experiment, there was a forward recoil of approximately 5.08mm, and a lateral movement of approximately 5.08mm.

During the second and third runs of the experiment, 10 ml of the fluid was injected into catheter 10. However, for this particular set of experiments, the flow rate of the fluid was increased to approximately 4 ml / s and 6 ml / s, respectively. As shown in fig. 12, the amount of catheter recoil and whiplash movement under these experimental conditions was also minimal, ranging from 3.81 mm to 15.24 mm.

Similar tests were also performed on conventional catheters. One of the conventional catheters did not include openings along its stem portion, while the other conventional catheter included two non-angled openings along its stem section. As shown in Figure 12, the amount of lateral movement due to fluid flow forces for conventional catheters was similar to that of the present invention. However, the amount of recoil was dramatically greater for conventional catheters compared to the catheter of the present invention.

Therefore, as shown in Figure 12, the data from the prototypes of the present invention confirm that the number, size, and arrangement of openings 42,44 in stem 16 and tip sections 18 substantially influence the forces of the fluid flow. As such, proper balancing of catheter parameters can substantially reduce or eliminate whiplash and / or kickback movements of the catheter body during injection procedures.

A second set of fluid reflux test experiments was also performed on the catheters 10 of the present invention. As shown in Figure 13, 10 ml of fluid was injected into catheters 10 at flow rates ranging from 4 ml / s to 8 ml / s. Each catheter 10 was tested in two positions on the trial piece 60. In the first position, the distal end 20 of the catheter tip 18 was contained in the through hole 66 of the spacer wall 68 of the trial 60. In the second position, the distal end 20 of the catheter tip 18 extends beyond the through hole 66 of the separating wall 68.

In general, catheter 10 having twelve angled holes generated less fluid backflow than catheter 10 having eight angled holes. Furthermore, as shown in Figure 12, there appears to be a lesser amount of stained fluid in the downstream chamber when the catheter tip 18 was contained in the through hole 66 of the separating wall 68, in contrast to the wall 68 which is extends beyond.

Therefore, as with catheter recoil and lateral movement, the arrangement and configuration of the openings 42,44 in the stem 16 and tip 18 sections substantially influence fluid backflow. Furthermore, as shown in FIG. 12, fluid flow rate and catheter tip 18 at the injection site also have an effect on fluid reflux for catheter 10 of the present invention.

Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this discussion, may generate additional embodiments and modifications8

ES 2 245 679 T3 final without departing from the scope of the claimed invention. Accordingly, it should be understood that the drawings and descriptions in this document are offered by way of example to facilitate an understanding of the invention and should not be construed as limiting the scope of the invention.