Pressure responsive valve catheter

Abstract: A catheter (10) for introducing material into the vascular system is provided. The catheter includes an elongated catheter body (12) having a side wall (14) defining a catheter lumen (16). The catheter body has a proximal portion (18). Material can be introduced into the catheter lumen at its proximal portion. The catheter body has a distal portion (22). The distal portion has a single wall in an exit zone (24). At least one pressure responsive exit (26) is formed in the side wall of the distal portion of the catheter body. The pressure responsive exit permits material to exit from the catheter lumen in response to a pressure over a first pre-determined amount while preventing material from entering into the catheter lumen at a pressure less than a second pre-determined amount.

Description: BACKGROUND OF THE INVENTION The present invention relates to a catheter for use in the vascular system and, more particularly, to such a catheter which is formed with pressure responsive valves therein. Catheters for delivery of fluids into the vascular system are known in the art. These catheters include a catheter lumen having a proximal end through which material is introduced into the catheter lumen and a distal end from which fluid exits from the catheter lumen. Some catheters are formed with a single distal end hole which serves both as a means of egress for the fluid and a passageway through which a guide wire can fit. In addition to an end hole some catheters are formed with multiple side holes. The provision of multiple side holes permits better mixing of fluid with blood, avoids a strong end hole jet, and permits a slightly higher flow rate. Some catheters with side holes have no end hole. Without an end hole the catheter cannot be used with a guide wire. Catheters with multiple side holes may have problems with uniform fluid distribution. Additionally, multiple side holes create a problem where the guide wire may inadvertently exit from a side hole instead of from the end hole. Further, and especially where non-ionic contrast media is used, blood tends to clot at the side holes, which may cause delivery problems. Further, side holes are completely open and vulnerable to the ambient conditions surrounding them. Thus, when the catheter is in the vascular system it is possible, even at low pressure gradient, to get blood flow through the side holes into the catheter creating the possibility of clot formation in the side hole. Further, the use of multiple side holes can cause the outer wall of the catheter to be less smooth than desired resulting in an inadvertent gouging of the tissue. This is a bigger problem where the catheter is introduced at a site remote from the site where the fluid is to be delivered. Catheters formed with slits, instead of holes, in the distal segment of the catheter are known in the art. The provision of slits in lieu of holes is intended to overcome some of the problems created by catheters with multiple side holes. A catheter formed with distal slits is disclosed in U.S. Patent No. 3,888,249 issued to David L. Spencer on June 10, 1975. The Spencer Patent disclosed a catheter for infusion of medication into an artery. The medication flows through the catheter lumen and exits into the artery through the distal slits which act as valves. The '249 catheter has a double wall in the area of the slits. It includes an inner wall with windows formed therein and an outer wall formed with slits therein. The slits overlie the windows. The modulus of elasticity of the outer wall is less than the modulus of elasticity of the inner wall and this difference in the elasticity of the two walls permit the slit/window combination to act as a valve. Another example of a catheter formed with slits rather than holes is disclosed in U.S. Patent No. 4,973,319 issued to Gerald S. Melski on November 27, 1990. The Melski Patent discloses a catheter for infusing fluids into a vein or artery. The fluids to be infused are therapeutic agents or nutrients. The Melski catheter, like the Spencer catheter, has a double wall in the area of the slits. The Melski catheter has an inner wall with apertures formed therein covered by an outer wall with slits formed therein. Melski discloses the use of a medical grade silicone rubber for both his inner and outer wall. However, Melski makes it clear that the inner wall should be made of a stiffer material than the outer wall in order for the two walls to work together to provide a one-way valve. The catheters disclosed in the '249 and '319 patents may prove useful for delivering fluids at low pressure into the vasculature. Where a high pressure delivery is needed however. The use of two walls to create the valve makes the valve incapable of withstanding repeated high pressure and/or high velocity injections. The walls may delaminate under these circumstances and the catheter would fail. An additional problem with the two walled construction described in these patents is that they have a step on the exterior surface of the catheter, where the inner tube fits into the outer tube, and this step provides a location for clot formation. An additional problem with the catheters disclosed in these patents is that they are relatively expensive to manufacture and fluid distribution problems may arise if the windows and slits are not properly aligned. When catheters are used for certain procedures it is desirable to insert the catheter at a site remote from the site where the fluid is to be injected. In such cases the catheter must be steered through the somewhat tortuous vasculature. In order to so do, the catheter itself must possess sufficient stiffness, torqueability, and pushability. In the alternative the catheter may be constructed for use with a guide wire, the guide wire providing the needed stiffness, torqueability, and pushability characteristics. Where a guide wire is to be used with a catheter, the catheter must be provided with an end hole. However, end holes can create problems when it is desired to deliver fluid with a uniform distribution along the length of the distal portion of the catheter. Thrombolysis involves the dissolving of blood clots in the vascular system. There are a large number of people who need to have such blood clots dissolved. It has been proposed that the blood clots could be more efficiently lysed if the lytic agent were delivered to the clot at high velocity using a forceful injection. This would reduce the time needed to complete the procedure. For optimal lysing, the lytic agent should be delivered at an even flow rate at the desired high pressure required for high velocity impact from exits provided along a predetermined length of catheter. Yet this high pressure/even flow rate function must be provided by a catheter which prevents back flow of blood into the catheter at ambient pressure. A catheter for introducing material into the vascular system comprising an elongated catheter body having a sidewall defining a catheter lumen, the catheter body having a proximal portion with means through which material is introduced into the catheter lumen and a distal portion, said distal portion being a single wall in an exit zone and including at least one pressure responsive exit in the form of a slit formed in the sidewall of the distal portion of said catheter body, said pressure responsive exit permitting material to exit from said catheter lumen, is known from US-A-4 327 722. (see also the features defined in the preamble of claim 1). This known catheter has a rather unflexible and therefore stiff distal end portion. This makes it difficult or rather impossible to lead it into remote vascular areas requiring high flexibility and steerability of the distal end portion. Moreover, the known catheter has a closed end so that it cannot be used with a guide wire. In Figs. 5c and 5d of US-A-4 327 722, a catheter is shown having flexibility and stiffness characteristics enabling access to a major vein, for example the subclavian. However, this known catheter is too stiff to obtain access to remoter portions of the vascular system. A further catheter is known from US-A-3 841 308. This known catheter includes a tube-like element having an open end which is closed by a closure. This closure is attached to a rod-like element and is moved in outwards direction by a compression spring. The only purpose of this compression spring is to urge the closure into opening direction. An angioplasty catheter assembly is known from EP-A-0 231 601. This assembly is for the purposes of angioplasty which is to use a balloon in order to compress the plaque on the vascular wall of an artery so as to decrease a constriction and to increase blood flow. There is an optical bundle (see Fig. 4) providing laser energy to drill a hole through a clot which may be substantially blocking a particular blood vessel and then advance the catheter assembly and expand the balloon to compress the plaque and open up the cross-section for the blood flow. Thus, the known catheter assembly provides balloon angioplasty coupled with laser for removal of plaque. Proceeding from this prior art, it is the underlying objective of the invention to provide an infusion catheter for introducing material into the vascular system of a human body. The material may be a chemical intended to dissolve thrombus or a blood clot respectively. The solution to this objective as provided by the invention comprises the following unique combination of features: (a) comprising an elongated catheter body having a sidewall defining a catheter lumen, the catheter body having a proximal portion with means through which material is introduced into the catheter lumen and a distal portion, said distal portion being a single wall in an exit zone and including at least one pressure responsive exit in the form of a slit formed in the sidewall of the distal portion, (b) said slit opening in response to a first predetermined pressure from within said lumen to permit material to exit through said open slit from said catheter lumen, (c) said slit remaining closed up to a second predetermined pressure from outside said catheter lumen to prevent flow into said lumen through said slit up to said second pressure, said second pressure being substantially greater than said first pressure, characterised by (d) a seat including an end hole at the distal end of the distal portion, said end hole being shaped and dimensioned to accommodate a correspondingly shaped occluding ball moveable between one position engaging said end hole to prevent material from exiting therethrough and another position leaving said end hole open to accommodate a guide-wire, and (e) an occluding wire attached to and extending from said occluding ball towards said proximal portion to move the occluding ball between its two positions. Suitable further embodiments of this basic design form the subject matter of subclaims. The foregoing and other features of the present invention will become more apparent after a consideration of the following detailed description taken in conjunction with the accompanying drawings in which preferred forms of the present invention are illustrated. In the drawings: Fig. 1 is a side elevational view of one embodiment of the catheter of the present invention. Fig. 2 is an enlargement of a portion of the distal end of the Fig. 1 catheter showing the slits in a closed position. Fig. 3 is a view analogous to Fig. 2 showing a slit in an open position. Fig. 4 is a sectional view taken generally along line 4 - 4 of Fig. 3 and indicating the direction of flow of material outwardly from the catheter slit. Fig. 5 is an enlarged view of the distal end of another embodiment of the catheter of the present invention showing a slit in the closed position. Fig. 6 is a view analogous to Fig. 5 showing the slit in the closed position. Fig. 7 is a sectional view taken generally along line 7 - 7 of Fig. 8 and indicating the direction of flow of material outwardly from the catheter slit. Fig. 8 is a side elevational view of another embodiment of the catheter of the present invention. Fig. 9 is an enlargement of a portion of the distal end of the Fig. 8 catheter showing a slit in an open position. Fig. 10 is a sectional view taken generally along line 10 - 10 of Fig. 9. Fig. 11 is an elevational side view of an occluding wire intended for use with Figs. 1 through 7 and 8 through 10 embodiments. Fig. 12 is a sectional view of the embodiments shown in Fig. 5 or 8 showing an occluding ball seated in the catheter distal taper and the end hole sealed. Fig. 13 is analogous to Fig. 12 showing the ball unseated and the end hole open. Fig. 14 is a view of the catheter in Figs. 1 through 7 with radiopaque markers on the catheter shaft. Fig. 15 is a view of variable infusion length catheter with the sleeve on the outside. Fig. 16 is a view of a variable infusion length catheter with the sleeve in the catheter internal diameter. Referring now to the drawings and more particularly to Figs. 1 through 7 and 8 through 16, the reference numeral 10 denotes one embodiment of the catheter of the present invention. Catheter 10 is designed for delivering fluid into the vascular system. One intended use of catheter 10 is to deliver fibrolynitic agents to the site of blood clots to aid in lysing of the same. These fibrolynitic agents are delivered at low volumes and high velocities. For example, the volume is typically 0.2 ml to 0.5 ml (milliliters) over 5 to 50 milliseconds. For optimal lysing the fibrolynitic agent should be delivered with an even distribution so that the blood clots are dissolved in an accelerated and an efficient manner. Another intended use of catheter 10 is to deliver contrast media at a high, even flow rate for angiographic studies. Catheter 10 has an elongated catheter body 12 with an annular side wall 14 defining a catheter lumen 16. The catheter body 12 has a proximal portion 18 with an opening (not shown) through which fluid is introduced into the catheter lumen. Catheter body 12 has a distal portion 22. The distal portion 22 includes an infusion length 24 with a plurality of slits 26 which serve as pressure responsive valves. In at least the areas of the infusion length 24, the catheter sidewall is a single wall. As best shown in Figs. 12 and 13, the distal portion 22 of catheter sidewall 14 includes a tapered zone 13. This taper 13 creates a seat 40 for an occluding ball 38 associated with an occluding wire 41. The inner diameter of the two portions of the catheter sidewall 14, proximal and distal of the taper 13, can vary dependent upon the intended use of catheter 10. In one embodiment of the invention, the catheter 10 has an inner diameter of about 1.19 mm (0.047 inches) and the end distal of the taper 13 is a straight portion 23 having a length of about 5.08 mm (0.20 inches) and an inner diameter of about 0.94 mm (0.037 inches). The taper zone 13 has an angle of approximately 20 degrees and a length of about 0.51 mm (0.02 inches). Occluding wire 41 includes a distal coil spring 36 having an outer diameter of about 0.89 mm (0.035 inches). Distal coil spring 36 protects the arterial wall from the catheter tip. Occluding ball 38 has a diameter of about 1.12 mm (0.044 inches). When advanced in catheter 10, the occluding ball 38 seats in the taper 13 to seal the distal end hole 22c of catheter 10. By sealing end hole 22c fluid flow from the distal end hole 22c is prevented. Occluding wire 41 may be retracted to open end hole 22c. When the occluding ball 38 is seated and end hole 22c is sealed, all fluid flow is from the slits 26. When the occluding ball is not seated in the taper 13, both fluid and an associated guide wire (not shown) may exit from the end hole 22c. Occluding wire 41 may be provided with a proximal platinum radiopaque marker 42 (see Fig. 11). When the occluding wire 41 is in place in the catheter, the marker 42 indicates the location of the most proximal slit. The occluding ball 38 helps locate the most distal slit. This aids in use of catheter 10 with fluoroscopy. Another way to identify the infusion length and show slit locations can be done by placing radiopaque markers 50 on the catheter body 10 itself, as shown in Fig. 14. A marker 50 could be placed on the shaft, just proximal of the first proximal slit and just distal of the last distal slit. This would allow the catheter to be used with a conventional guide wire and yet still show slit locations. Catheter 10 is formed of a relatively non-compliant material and in the preferred embodiment is formed of nylon. Material schould have a flexural modulus in the range of 206.8 x 10 6 Pa to 0.68 x 10 9 Pa (3 x 10 4 PSI to 1.0 x 10 5 PSI and be able to withstand internal pressures of at least 7,580 x 10 3 Pa (1,100 PSI). Slits 26 are integral with the catheter wall. The response of slits 26 to pressure is related to the flexural modules of the slits, and the deflection of the slits is proportional to WL 3 /E where W equals load in pounds, L equals length in inches of the slits and E equals flexural modules of the material. The slits 26 are formed so that they will not deflect into the catheter lumen when the catheter is steered around a curve. This is necessary to allow catheter 10 to be advanced in the vasculature. The number of rows of slits and the area taken up by the slits in any radial plane, should be such that the tensile and compression strength of the catheter is not greatly compromised. This too allows the catheter to be advanced through the vasculature. The slits 26 should take up no more than about 20 % of the side wall area in any radial plane and extend proximally along the shaft for a length of about 40 % of the catheter length. As catheter 10 is formed of a relatively non-compliant material, sidewall 14 does not swell when subjected to high internal pressures. Due to this, when catheter 10 is exposed to increased internal pressure, slits 26 flex open allowing fluid to flow from the interior lumen of the catheter therethrough. In each single embodiment of catheter 10 all of the slits 26 are of the same geometry and material and thus the load which will open each slit is the same. The slits will thus open almost simultaneously. When fluid is rapidly infused into the catheter, the pressure rise within the catheter lumen will be fast resulting in an approximate uniform load on all slits to result in a uniform flow of material out of all of the slits. Slits 26 open at a first predetermined internal pressure to allow material to exit from the catheter lumen. Slits 26 will not open, under ordinary circumstances, in response to external pressure. The slits 26 thus prevent back flow of material into the catheter 10. The slits 26 resist opening at low internal pressures and this allows flushing of the entire length of the catheter without problems of clot formation at the distal catheter end. In a preferred embodiment the infusion length 24, encompassing the set of slits 26, is between 24.99 mm (0.984 inches) to 199.99 mm (7.874 inches) in length. As shown in Figs. 1 through 4 and 8 through 10, slits 26 may be straight. The straight slits are equal in size and are equidistant from one another. The straight slits are longitudinally spaced from one another by 2.54 mm (0.1 inches) and are regularly spaced apart from one another by 90 degrees to thus provide four slits at each 2.54 mm (0.1 inch) interval along the length of the exit zone. The straight slits may be at an angle of about 45 degrees to a longitudinal side wall line. Alternatively they may be parallel to a longitudinal side wall line. The minimum opening pressure for the straight slits is 6.89 x 10 3 Pag (one (1) psig). The straight slits will hold 20.7 x 10 3 Pag (three (3) psig) before allowing fluid to flow inwardly into the catheter. The slits allow good penetration and distribution of the fibrolynitic agent. Alternatively, slits 26 may be semicircularly shaped. The semicircular slits each have a diameter of about 1.65 mm (0.065 inches) and are spaced longitudinally apart from one another by 2.54 mm (0.1 inches) and are radially spaced from one another by 90 degrees to provide one semicircular slit at 2.54 mm (0.1 inch) intervals along the infusion length 24. The semicircular slits have minimal opening pressure of 6.89 x 10 3 Pag (1 psig) and will hold 20.7 x 10 3 Pag (3 psig) before allowing fluids to flow inwardly into the catheter. In the preferred embodiment, catheter 10 is a 5 French catheter. In one embodiment, the 5 French catheter is about 899.16 mm (35.4 inches) long. In another embodiment, the 5 French catheter is about 1348.74 mm (53.1 inches) long. The 899.16 mm (35.4 inch) catheter has an infusion length 24 of between 99.06 mm (3.9 inches) and 198.12 mm (7.8 inches). The 1348.74 mm (53.1 inch) catheter has an infusion length of between 99.06 mm (3.9 inches) and about 198.12 mm (7.8 inches). Where straight slits are used in a catheter with a 94.06 mm (3.9 inch) infusion length 24, there are eighty slits, each having a length of 0.76 mm (0.03 inches). Where the straight slits are used in a catheter with a 198.12 mm (7.8 inch) infusion length, there are one hundred and sixty slits each having a length of 0.38 mm (0.015 inches). Alternatively, another design is shown in Fig. 15. This design shows a catheter such as those in Figs. 1 through 7 and 8 through 10 having a sleeve 60 over the outer wall of the catheter. Sleeve 60 fits with a radial clearance of about 0.025 mm (one mil (0.001 inches)). The sleeve 60 is made of a low friction polymer such as a polyolefin or fluoropolymer. Markings 70 on the catheter show advancement distance of the polymer sleeve down the body of the catheter 10. Sleeve 60 is used to selectively cover the catheter slits 26 to prevent flow therethrough. The sleeve 60 provides high resistance against flow trying to exit from the covered slits. As fluid follows the path of least resistance it will exit from the non-covered slits. The use of sleeve 60 allows the user to adjust the desired infusion length by selectively covering some slits. The proximal end of sleeve 60 has a hub 80 for gripping. Radiopaque markers 85, 90 are provided at the distal end of the infusion zone and at the distal tip of the sleeve 60. Fig. 16 shows another method of providing the same variable infusion length. A sleeve 91 that fits into the inner diameter of the catheter is provided. A fitting 92 consisting of a body 92a, a cap 92b, and a grommet 92c is connected to the catheter hub. Sleeve 91 fits into the grommet and is advanced into the inner lumen of the catheter. Sleeve 91 is made of a polyolefin or fluoropolymer material, and has a distal tip radiopaque marker 93 and proximal hub 94. There are depth indicators 95 on sleeve 91. Advancing sleeve 91 into the catheter seals off slits thus giving variable infusion length. The slit infusion length is discernable using a radiopaque marker 93 on the sleeve 91 and a distal infusion length radiopaque marker 50 on the catheter. The occluding ball can also act as a distal infusion length marker.

Claims: Infusion catheter (10, 100) for introducing material into the vascular system (a) comprising an elongated catheter body (12) having a sidewall (14) defining a catheter lumen (16), the catheter body (12) having a proximal portion (18) with means through which material is introduced into the catheter lumen (16) and a distal portion (22), said distal portion (22) being a single wall in an exit zone and including at least one pressure responsive exit in the form of a slit (26) formed in the sidewall (14) of the distal portion, (b) said slit (26) opening in response to a first predetermined pressure from within said lumen (16) to permit material to exit through said open slit (26) from said catheter lumen (16), (c) said slit (26) remaining closed up to a second predetermined pressure from outside said catheter lumen (26) to prevent flow into said lumen through said slit up to said second pressure, said second pressure being substantially greater than said first pressure, characterised by (d) a seat including an end hole (22c) at the distal end of the distal portion (22), said end hole (22c) being shaped and dimensioned to accommodate a correspondingly shaped occluding ball (38) moveable between one position engaging said end hole (22c) to prevent material from exiting therethrough and another position leaving said end hole (22c) open to accommodate a guidewire, and (e) an occluding wire (41) attached to and extending from said occluding ball (38) towards said proximal portion (18) to move the occluding ball (38) between its two positions. Catheter (10, 100) according to claim 1, characterized in that said catheter lumen (16) is tapered at its distal end to form said seat including said end hole (22c). Catheter according to claim 1, characterized in that the occluding wire (41) includes a distal coil spring (36) extending through said end hole (22c) away from said occluding ball (38).

Inventors: APPLING WILLIAM M, BOOKSTEIN JOSEPH J, HOBBS EAMONN, RECINELLA DANIEL K, ZIMMET ARTHUR L, APPLING, WILLIAM M., BOOKSTEIN, JOSEPH J., HOBBS, EAMONN, RECINELLA, DANIEL K., ZIMMET, ARTHUR L.
Applicants: ANGIODYNAMICS INC, ANGIODYNAMICS, INC.
Application year: 1991
Main classification: A61M25
IPC codes: A61B17, A61M25