Spring devices – Coil – Conical
Reexamination Certificate
2000-05-25
2002-04-16
Butler, Douglas C. (Department: 3613)
Spring devices
Coil
Conical
C267S156000, C267S166000, C029S896900, C148S908000, C604S009000
Reexamination Certificate
active
06371464
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to surgically implanted physiological shunt systems and related flow control devices. More particularly, the present invention relates to a spring in a shunt system including a one-way flow control valve for controlling the flow of cerebrospinal fluid out of a brain ventricle and preventing backflow of fluid into the brain ventricle.
2. Description of Related Art
In the medical arts, to relieve undesirable accumulation of fluids it is frequently necessary to provide a means for draining a fluid from one part of the human body to another in a controlled manner. This is required, for example, in the treatment of hydrocephalus, an ailment usually afflicting infants or children where fluids accumulate within the skull and exert extreme pressure and skull deforming forces.
In treating hydrocephalus, cerebrospinal fluid accumulated in the brain ventricles is typically drained away utilizing a drainage or shunt system including a catheter inserted into the ventricle through the skull, which is connected to a tube that conducts the fluid away from the brain to be reintroduced into the peritoneal cavity or into the vascular system, as by extending a distal catheter through the patient's jugular vein to the atrium portion of the heart.
To control the flow of cerebrospinal fluid and maintain the proper pressure in the brain ventricle, a pump or valve is placed in the conduit between the brain and the peritoneal cavity or the heart. An exemplary flow control device is found in U.S. Pat. No. 4,560,375.
Although such drainage systems have provided successful results, a problem of overdrainage of the cerebrospinal fluid from the brain ventricles sometimes exists. Overdrainage of cerebrospinal fluid may result in excessive reduction of the cerebrospinal fluid pressure within the brain ventricles and predispose the development of a subdural hematoma or hydroma, and excessive reduction of ventricular size leading to shunt obstruction because of impingement of the ventricular walls on the inlet holes of the ventricular catheter.
This overdrainage can be caused by the siphoning effect of hydrostatic pressure in the distal shunt catheter. The siphoning effect of hydrostatic pressure may be created by the elevation of the ventricular catheter inlet with respect to the distal catheter outlet (i.e., when the patient sits, stands or is held erect). In order to prevent such overdrainage caused by the siphoning effect of hydrostatic pressure in the distal shunt catheter, siphon control devices have been placed in the conduit, typically between the flow control device and the peritoneal cavity or the heart. An exemplary siphon control device is found in U.S. Pat. No. 4,795,437.
It is desirable in some instances to permit the physician to be able to alter the flow characteristics through the drainage system after it has been subcutaneously implanted. To this end, on-off devices have been provided for implantation as a portion of the fluid conduit as an additional element of the shunt. An exemplary on-off device is shown in U.S. Pat. No. 3,827,439. Moreover, flow control devices have been provided which utilize a plurality of flow control valves having different flow control characteristics, which provide, alternative fluid pathways therethrough such that selection of a desired fluid pathway can be made by the selective percutaneous manipulation of the device when subcutaneously implanted. Such flow control devices having selectable alternative fluid pathways are shown in U.S. Pat. Nos. 5,154,693 and 5,167,615, the contents of which are incorporated herein in their entireties by reference.
These prior fluid shunt devices have all shared one important limitation: they only permit fluid flow therethrough upon achieving at most two fluid pressure differentials at the inlet and outlet of the device. In treating hydrocephalus, however, it is often desirable to vary the device “opening” pressure differential in accordance with ventricle size and treatment objective. For example, initial treatment may require a lower than normal pressure differential to initiate shrinkage of the ventricles, but as the ventricles decrease in size, the pressure differential should be increased gradually so that when the ventricle is returned to normal size the intraventricular pressure is at its normal value and the intracranial force systems are in balance (i.e., the opening differential pressure is set at a level that will stabilize the ventricles at a desired size). Generally speaking, the opening differential pressure should be varied inversely with the ventricle size. It is desirable to leave a lower pressure valve in a patient after the ventricles are again normal size, because the ventricles can further collapse, leading to a condition known as “slit” ventricles.
A further reason for providing adjustability in the opening pressure differential is to correct for variations in nominal opening pressure differentials typical in manufactured valves. With an adjustable valve, the opening pressure differential can be more accurately set at the factory and can be checked and corrected if necessary in the operating room prior to implantation.
Accordingly, there was a need in the medical arts for convenient and effective physiological drainage systems for controlling the flow of fluid from one part of the body to another, which are relatively inexpensive to manufacture, permit fluid flow therethrough only when upstream fluid pressure exceeds downstream fluid pressure by a selected pressure differential, and also provide means for altering the selected pressure differential by percutaneous manipulation of the device when it is subcutaneously implanted. Moreover, such a flow control device was needed that incorporates an integral siphon control device that opens only in response to positive upstream fluid pressure, and re-closes or remains closed in the absence of such positive upstream fluid pressure or in response to negative downstream hydrostatic pressure on the device.
These objectives were met in the invention described in U.S. Pat. No. 5,637,083, issued Jun. 10, 1997 to William J. Bertrand and David A. Watson entitled “IMPLANTABLE ADJUSTABLE FLUID FLOW CONTROL VALVE”, assigned to the assignee of the present invention, the contents of which are incorporated herein in its entirety. The invention described in the '083 patent resides in an improved subcutaneously implantable and percutaneously adjustable fluid flow control device useful in a physiological shunt system for controlling the flow of fluid from one part of the body to another. The fluid flow control device includes components responsive to an external or percutaneously-applied magnetic field, to provide the device a variety of pressure/flow characteristics.
In accordance with the invention described in the '083 patent, the fluid flow control device comprises an inlet, an outlet and valve means for controlling the fluid flow from the inlet to the outlet. The valve means comprises a valve housing including a fluid passageway therethrough that has a peripheral surface that forms a valve seat, and a valve element having a diameter larger than the valve seat. Means are provided for biasing the valve element against the valve seat so as to keep the fluid passageway closed until a fluid pressure differential between the inlet and the outlet exceeds a selected valve opening pressure. Further, a pump is situated between the inlet and the valve means. The pump provides means for flushing fluid through the device by the application of percutaneous pressure to the pump.
In one preferred form of the invention of the '083 patent, the valve housing includes a threaded aperture and a flow regulator insert which is threaded into the aperture to define the fluid passageway. Means are provided for adjusting the amount of bias applied to the valve element by the biasing means. In particular, the adjusting means includes a fixed dual concentric stair-step array and an overlying rotor as
Bertrand William Jeff
Porche Leonard
Solis Mitchell
Kinghorn Curtis D.
Medtronic Inc.
Patton Harold R.
LandOfFree
Valve spring does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Valve spring, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Valve spring will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2847247