Attitude and pressure responsive valve

A valve assembly for relieving intracraneal pressure includes a valve housing adapted for implantation and having an inlet port for connection to a ventricular catheter and an outlet port for connection to a venus or peritoneal catheter. The valve housing includes a fluid passage, the flow through which is controlled by a first pressure responsive valve of relatively high resistence and a second pressure responsive valve of relatively low resistence spaced downstream of said first pressure responsive valve. An attitude responsive valve is disposed in said fluid passage in parallel with said first pressure responsive valve. The valve assembly is implanted in a patient with the attitude responsive valve in a closed position when the patient is in an upright position and in an open position when the patient is in a horizontal position. The employment of pressure responsive and attitude responsive valves in parallel provides ventricular pressure relief regardless of the patient's position.

BACKGROUND OF THE INVENTION 
The present invention relates generally to a valve for providing pressure 
relief in response both to attitude and pressure conditions, and relates 
more particularly to such a valve adapted for implantation to relieve 
intracraneal pressure in treatment of hydrocephalus. 
Devices for draining ventricular fluid in cases of hydrocephalus have been 
available for some time. An early example of such a device is shown in my 
U.S. Pat. No. 2,969,066, issued Jan. 24, 1961. These devices essentially 
are pressure responsive valves which open upon the occurrence of a 
predetermined gradient across the valve to allow flow of cerebrospinal 
fluid sufficient to lower the ventricular pressure to the desired level. 
Since the typical cerebrospinal fluid shunt valve responds only to the 
fluid pressure gradient, such valves are unable to accommodate changes in 
attitude of the patient if the valve discharges into a catheter of 
considerable length such as a peritoneal catheter, since the pressure at 
the upper end of the catheter into which the valve discharges in a 
pressure gradient responsive valve controls the actual pressure relief 
achieved. Accordingly, such a valve implanted in a patient's head and 
utilizing a lengthy peritoneal catheter would function normally only when 
the patient were in an upright position, but would not produce the desired 
relief when the patient were in the horizontal position because of the 
substantial increase in the pressure at the discharge port of the valve. 
SUMMARY OF THE INVENTION 
The present invention overcomes the above shortcoming of prior art shunt 
valves by providing a valve assembly which is responsive both to attitude 
and pressure. This is accomplished by a parallel arrangement of a pressure 
responsive valve and an attitude responsive valve, thus providing an 
alternate flow path dependent upon the patient's attitude. The pressure 
responsive valve is designed to open under a relatively high pressure 
gradient, while the attitude responsive valve will open when the patient 
is in a substantially horizontal position. A second pressure responsive 
valve opening under a relatively low pressure gradient is provided at the 
outlet of the valve assembly, primarily to guard against fluid backflow. 
It is accordingly a first object of the invention to provide a shunt valve 
for treatment of hydrocephalus which is both pressure responsive and 
attitude responsive to provide relief of intracraneal pressure regardless 
of the attitude of the patient and the length of the catheter into which 
the valve discharges. 
A further object of the invention is to provide a valve as described of a 
relatively simple construction which can readily be miniaturized, and 
which can be fabricated of materials suitable for implantation. 
Additional objects and advantages of the invention will be more readily 
apparent from the following description of a preferred embodiment thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawings and particularly FIGS. 1-3 thereof, a valve 
assembly 10 in accordance with the present invention is shown connected at 
its upper end with a ventricular catheter 12 and at its lower end with a 
venous or peritoneal catheter 14. The valve assembly and attached 
catheters are adapted for placement beneath the skin of a hydrocephalitic 
patient in the position generally shown in FIG. 2 with the perforated 
distal end 16 of the ventricle catheter being appropriately located in a 
region of accumulated cerebrospinal fluid to provide fluid pressure relief 
as required. The fluid drained by the ventricle catheter 12 as regulated 
by the valve assembly 10 passes through the catheter 14 preferably into 
the peritoneal cavity of the patient or, alternately into the venous 
system. Although the valve assembly is conventionally placed behind the 
mastoid prominence as illustrated, when used with a peritoneal catheter it 
may alternately be located in the chest region. This latter location 
minimizes the risk of infection in the brain area, especially should 
complications arise requiring a repositioning, reattachment or replacement 
of the assembly. 
Since valve assemblies for relieving ventricular pressure are typically of 
the type opening in response to the relative pressure between the 
ventricular catheter and the peritoneal or venous catheter, a markedly 
different relief function is provided when the patient's position changes 
from an upright to a reclining attitude due to a change in pressure at the 
outlet end of the valve assembly. For example, in FIG. 2 with the 
patient's upper body in an upright position such as when sitting or 
standing, the valve outlet pressure will be relatively low since the fluid 
column within the lower catheter will be in an essentially vertical 
attitude. In contrast, when the patient is in a reclining position as in 
FIG. 3, the pressure at the valve outlet will be significantly higher 
since the fluid in the peritoneal or venous catheter will be substantially 
horizontal. 
As a result, since the valve assembly components are normally selected to 
effect the desired pressure relief function when the patient is in the 
upright position of FIG. 2, the desired relief function cannot be obtained 
when the patient is in the reclining position of FIG. 3 since the 
downstream catheter pressure will be substantially higher. The 
conventional type of valve would accordingly permit excessive ventricle 
pressure buildup when the patient is in the reclining position. If the 
valve were chosen to provide the appropriate pressure responsive opening 
when the patient were in the reclining position of FIG. 3, such a valve 
would produce excessive fluid drainage in the upright position of FIG. 2 
with potentially serious results. 
The present valve assembly 10 overcomes this shortcoming of conventional 
pressure responsive valves by incorporating therewithin an attitude 
responsive valve which will open only when the patient is in a reclining 
position. By employing the attitude responsive valve in the valve in 
parallel with the pressure responsive valve, appropriate pressure relief 
is attained regardless of the patient's position. 
The details of the present valve assembly 10 are shown in FIGS. 4-9 and 
include a resilient elongated valve housing 18 having a longitudinal axis 
20. The housing 18 is hollow, with the walls thereof defining a fluid 
chamber 22 extending most of the length of the housing. Both the housing 
18 and the fluid chamber 22 as shown in FIG. 7 are in section of a 
D-shape, one wall 24 of the housing being essentially planar and 
incorporating therewithin a fabric reinforcement layer 26. The fabric 
reinforced wall 24 extends at the four corners of the housing to form ear 
portions 27 which facilitate the anchoring of the valve assembly in place 
such as by means of ligatures. 
In order to permit fluid passage into the housing 22, a tubing connector 28 
is molded into one end of the housing, preferably in alignment with the 
longitudinal housing axis 20. The tubing connector 28 includes an 
outwardly extending portion 30 over which the proximal end of the 
ventricular catheter is disposed. An annular groove 31 in the connector 
portion 30 permits a peripheral constriction of the catheter such as by 
suture material (not shown) to provide a locking of the catheter to the 
connector and hence the housing. An axial passage 32 in the connector 
permits fluid flow from the catheter into the chamber 22. The end of the 
housing terminates in a collar portion 34 which protects the catheter 
connection from dislodging influences. 
A similar tubing connector 36 is provided at the opposite end of the 
housing 18, the connector 36 including ribs 38 over which the proximal end 
of the peritoneal catheter 14 is secured. A collar portion 40 of the 
housing 18 extends around the extending connector 36 to protect the 
attachment of the catheter 14. 
The connector 36 as illustrated is preferably formed as an integral part of 
a hollow valve casing 42 molded within the lower end of the housing 18 and 
within which is disposed a pressure responsive valve 44. An opening 43 in 
the casing 42 provides fluid communication from the chamber 22 into the 
casing 42 as controlled by the valve 44. The valve 44 opens in response to 
a relatively low pressure differential between the fluid in the chamber 22 
and that within the upper end of the catheter 14. 
The construction of the low pressure responsive valve 44 may be of a 
variety of types but is preferably as illustrated of a type comprising a 
valve body 46 of an elastic material having a central valve bore 48. The 
valve is of a diameter sufficient to fill the casing 42 at its upper end, 
but is narrowed into an elongated closed barrel portion 50 at its lower 
end. A pair of slits 52 in the closed end of the barrel portion permit 
expansion deformation of the end of the barrel portion and a flow of fluid 
through the slits upon the occurrence of a predetermined pressure 
differential between the fluid within the valve bore 48 and the hollow 
valve casing 42. The valve body 46 is retained in position at the upper 
end of the valve casing 42 by means of a retaining ring 54 cooperating 
with an annular rib 56 of the valve casing 42. 
The chamber 22 is divided by a bulkhead 58 disposed relatively close to the 
chamber inlet. The bulkhead includes a pair of parallel bores 60 and 62 
parallel with the longitudinal axis of the valve assembly and adapted 
respectively to receive a high pressure responsive valve assembly 64 and 
an attitude responsive valve assembly 66. 
The high pressure responsive valve assembly 64, which is in structure 
identical with the low pressure responsive valve 44, includes a hollow 
valve casing 68 having an upper opening 70 and a lower opening 72 therein. 
A valve element 74 within the casing 68 includes a valve body 76 having a 
bore 78 therein. A reduced diameter barrel portion 80 of the valve element 
74 includes a pair of slits 82 therein which, upon the occurrence of a 
predetermined pressure differential between the fluid present in the bore 
78 and the casing 68, opens in response to elastic deformation of the 
valve barrel portion. A retaining ring 84 cooperates with the annular rib 
86 of the casing 68 to secure the valve element 74 in place against the 
upper end of the casing 68. 
The attitude responsive valve 66 includes a hollow cylindrical valve casing 
88 having an upper inlet opening 90 and a lower outlet opening 92 therein 
to permit fluid passage therethrough. The casing 88 adjacent the outlet 
opening 92 is of a frusto-conical configuration to serve as a seat for a 
valve ball 96 which has a diameter less than the diameter of the casing 88 
but greater than that of the opening 92. The ball 96 will accordingly be 
guided by the frusto-conical portion 94 of the casing to seat directly 
over and seal the outlet opening 92 when the valve assembly is in a 
vertical attitude as shown in FIG. 4, but will roll under the force of 
gravity away from the opening 92 when the valve assembly is in a 
horizontal attitude as shown in FIG. 9. 
The high pressure responsive valve 64 is calibrated to require a 
substantial pressure differential to open, for example 180 mm H.sub.2 O. 
The low pressure responsive outlet valve 44, in contrast, should require 
only a small pressure differential to open, for example 10-20 mm H.sub.2 
O. The outet valve 44 is required principally to prevent possible back 
flow into the chamber 22. The outlet valve 44 additionally permits use of 
the lower portion of chamber 22 as a pumping chamber to test the 
operability of the implanted valve and catheter system. 
The operation of the valve assembly is automatic and provides a 
predetermined pressure relief to the cranial ventricles regardless of the 
patient's attitude. As indicated above, the valve assembly is implanted so 
as to be in a substantially vertical attitude when the patient is in an 
upright position, as shown in FIG. 2. The perforated distal end 16 of the 
ventricle catheter is located in the appropriate cavity to drain the 
cerebrospinal fluid as required to maintain the desired fluid pressure. 
The venous or peritoneal catheter 14 is similarly implanted in a well 
known manner to provide a flow path of drained fluid to the selected body 
region. 
Since the entire fluid drainage system including the ventricle catheter 12, 
the valve assembly 10 and the venous or peritoneal catheter 14 is at all 
times filled with fluid, it forms a fluid column of substantial length 
which in the absence of appropriate valve resistence, could, especially in 
the case of a peritoneal catheter, reduce the ventricle pressure to an 
undesireably low pressure. Accordingly, the high pressure responsive valve 
64 is chosen with a substantial pressure differential resistence and will 
normally operate only when the patient is in the substantially upright 
position, at which position the pressure at the upper end of the catheter 
14 is minimized and the pressure differential across the valve is 
greatest. 
When the patient assumes a horizontal position, the ball 96 as illustrated 
in FIG. 9 falls away from the opening 92, thereby opening a flow path 
through the valve casing 88 bypassing the pressure responsive valve 64. 
The opening of either the pressure responsive valve 64 or the attitude 
sensitive valve 66 will normally be sufficient to simultaneously open the 
outlet valve 44 and permit a fluid flow into the catheter 14. 
The portion of the chamber 22 downstream of the bulkhead 58 may be utilized 
as a pumping chamber to test the operability of the valves in the manner 
described in the above-mentioned U.S. Pat. No. 2,969,066. Since the 
implantation is just beneath the skin, this portion of the chamber may be 
manually compressed to force fluid within the chamber through the outlet 
valve. 
The portion of chamber 22 upstream of the bulkhead 58 may be utilized as a 
convenient injection cavity for introduction of medication or for 
monitoring the pressure being maintained by the valve assembly. 
The elastic portions of the valve assembly including the valve housing, 
bulkhead and the elastic pressure responsive valves are preferably made of 
a rubber like material such as Silastic or other elastomeric polymer 
suitable for implantation. The rigid elements including the several valve 
casings and the tubing connectors are preferably made of type 316 
stainless steel or other suitable metal. The ball 96 may also be made of a 
heavy metal such as stainless steel although it may be advantageous to 
employ a precious metal such as gold to maximize the weight and hence the 
gravity force serving to operate this element. 
Although the pressure responsive valve type illustrated and described is 
preferred, other types of pressure actuated valves may also be employed, 
including but not limited to miter or fishmouth valves, ball type valves, 
or flap type valves. 
The attitude responsive valve should be a gravity actuated valve and is 
preferably of the free floating ball type as illustrated and described. A 
modified form of attitude responsive valve could comprise a very thin flow 
activated membrane or flap valve which would close when the patient stood 
up or sat up as a sudden increase of fluid flow would serve to close such 
a flap valve. 
Manifestly, changes in details of construction can be effected by those 
skilled in the art without departing from the invention.