Medical fluid flow control valve

Details Medical fluid flow control valve Medical fluid flow control valve

1998-07-30

2002-07-09

Sykes, Angela D. (Department: 3763)

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

C604S167040

Reexamination Certificate

active

06416499

ABSTRACT:

TECHNICAL FIELD
This invention relates generally to surgical devices, and more particularly to medical devices for controlling the flow of fluids through catheter introducers and other sheaths, cannulae, catheters, trocars, scopes and the like.
BACKGROUND OF THE INVENTION
It is now well known to perform a variety of surgical procedures by the introduction of an interventional device into the body, for example, into an arterial or venous blood vessel, or into a laparoscopic or other cavity artificially maintained in the body. Typical of the former type of procedure are coronary angiography (e.g., where an X-ray contrast fluid is inserted into the coronary artery) and percutaneous transluminal coronary angioplasty (PTCA). These and other procedures involve the introduction of an interventional device, such as a catheter (open or closed end), a wire guide, a balloon, a stent, an atherectomy device, or the like into the vessel or cavity in question. The single generic term “catheter” should be understood herein to include all of such interventional devices, unless the context limits the meaning of the term.
Procedures for introducing a catheter into a blood vessel include the cut-down method and the Seldinger technique. The Seldinger technique is well known, and first involves opening a blood vessel with a needle, inserting a guide wire into the vessel through the lumen of the needle, withdrawing the needle and inserting a dilator over the guide wire. The dilator is located inside an associated sheath which is also inserted into the vessel, and the dilator is sealed to the sheath by a hemostasis or hemostatic valve through which the dilator passes. The dilator is removed, and the catheter inserted through the sheath and hemostatic valve into the vessel.
During the performance of the Seldinger technique and other procedures, care must be taken to avoid the undesirable introduction of air into the vessel (air embolism) and the undesirable leakage of blood, other fluids or a cavity-pressurizing gas from the patient (as much for the protection of health care practitioners as of the patient). As procedures for introducing catheters and other interventional devices have become more widely accepted, the procedures have also become more diverse, and the variety of sizes and types of devices employed has grown dramatically. The risks of inward or outward leakage thus become greater.
Because of such variety in the sizes and types of catheters and other devices to be handled, it would be highly desirable to have a hemostatic seal or other check valve which seals an introducer sheath or other device with a high degree of effectiveness when no catheter or other interventional device lies across the seal or valve, and which is also capable of providing an acceptable seal to catheters and other interventional devices having a wide range of diameters. High resistance to tearing when penetrated by catheters and other interventional devices of large diameter is very desirable as well. It would also be valuable to have a hemostatic seal or other check valve which allowed the easy passage through the seal or valve of devices of a very wide range of diameters, without interfering with tactile feedback from the catheter or other interventional device. Such tactile feedback is also known simply as “feel.” It would also be desirable to have a hemostatic seal or other check valve which tolerated repeated insertions and withdrawals of catheters or other interventional devices without any appreciable decrease in the performance characteristics of the seal or valve, especially with respect to leakage and “feel.”
A variety of prior devices are known to act as hemostatic or check valves. For example, U.S. Pat. No. 5,273,546 (McLaughlin et al., Dec. 28, 1993) discloses a hemostasis valve including an elastomeric gasket, the gasket having at least one concave surface and a pin hole or slits through the central region of the gasket. The gasket is preferably composed of polyisoprene, but could also be composed of silicone rubber, natural rubber or a thermoplastic elastomer, such as an injection moldable synthetic rubber compound. The gasket material has a hardness of 30-50 Shore A, preferably 35-45 Shore A. One drawback of silicone rubbers and other materials of similar hardness is that such materials offer an inadequately soft and compliant texture, so that the “feel” of the catheter or other interventional device is less than adequate when the catheter or device is rotated or advanced. Selecting a silicone rubber of lower hardness is inadequate because the very low durometer silicone materials (below a hardness of 30 Shore A) do not currently offer the degree of resistance to tearing which would make the valve acceptably durable for surgical use.
U.S. Pat. No. 5,141,498 (Christian, Aug. 25, 1992) is directed to a flexible valve which includes a body having a cylindrical wall with a central bore therein, and at least three flexible leaflets adjoining the central wall. The valve body is composed of an elastomeric material, for example, a urethane compound having a hardness of 20-50 Shore A, preferably 35 Shore A. The patent notes that a “rubber-like” compound identified as “Krayton” can also be used. The valve of the reference is intended to remedy the specific drawbacks associated with the so-called “duckbill” type of valve having only two of such leaflets. Duckbill valves are well known to be subject to several drawbacks, not all of which are mentioned in the patent. First, duckbill valves sometimes invert when relatively large diameter catheters or other interventional devices are inserted through them and then withdrawn. Moreover, they sometimes possess a large well behind them which can trap air or blood therein; this well cannot be flushed out in the conventional manner, that is, by injection through the side arm (or extension tube) commonly present in devices incorporating hemostatic valves. Finally, duckbill valves commonly are unable to maintain a seal under a negative pressure or vacuum. This is seen, for example, when a health care practitioner draws on a syringe connected to the side arm; air is undesirably drawn through the valve and into the syringe and the body containing the valve. The Christian patent thus uses compounds of a specific type (along with the additional leaflet) to cure problems associated with a specific valve construction, and makes no general teachings about such compounds which would apply to other types of valves. Moreover, the patent does not appear to disclose or suggest that all of the indicated compounds were in fact useful over the entire range of hardness specified.
U.S. Pat. No. 5,025,829 (Edwards et al., Jun. 25, 1991) is directed to a parenteral check valve including a preloaded, perforate disk made of a thermoplastic elastomer, an elastomeric material or a thermoplastic material having a hardness of 35 to 100 Shore A. An example of such a material is a “KRATON” brand thermoplastic elastomer. (“KRATON” is believed to be a registered trademark of Shell Chemical Company.) The disk seals against a circular flange or ring on a perforate seat in the valve; fluid pressure moves the disk away from the flange to allow fluid flow through the perforation in the disk.
Finally, U.S. Pat. No. 5,342,315 (Rowe et al., Aug. 30, 1994, incorporating by reference the application leading to U.S. Pat. No. 5,545,142, Stephens et al., Aug. 13, 1996) discloses a variety of trocar seals made from elastomeric materials such as silicone, latex, rubber, polyurethane, “Kraton” (specifically, a thermoplastic elastomer of A-B-A type, in particular, styrene-isoprene-styrene block copolymer) or the like. It is believed that S-I-S type block copolymers typically have a hardness of 30 to 40 Shore A, comparable to the other identified elastomers, all of which lack the durability and resistance to splitting desirable for hemostatic valves and other check valves.
Again, it would be highly desirable to have a hemostatic valve or other check valve which overcomes the various drawbacks associated with these an

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