Ventricular by-pass valve for draining the cephalorachidian liquid in the hydrocephalus

The invention is a ventricular by-pass device for draining the cephalorachidian liquid in the hydrocephalus. It consists of a check valve device which obstructs the brain suction orifice.

BACKGROUND OF THE INVENTION 
This invention relates to a ventricular by-pass valve which is known in 
several countries and was originally designed in the United States of 
America in the year 1958. In the United States it is known as the Pudenz 
valve, in Japan as the Fuji valve, etc. 
In the original design, adopted by several countries, the valve consists of 
a biconvex structure having an intermedium veil, these three elements 
being made from a silicon rubber elastomeric material having a connection 
toward the brain and another connection toward the heart or peritoneum. 
This mechanism ensures the outflow of cephalorachidian liquid when it has 
been retained in the brain causing hydrocephalus. The arrangement of the 
different elements comprised by the valve causes it to function as a 
one-way pump too, which, through outside handling, produces faster 
ejection of the brain liquid. Experience has demonstrated that 
notwithstanding its excellent operating characteristics, this design is 
capable of eventual collapse by the unpredictable action of forces 
originated by the elastomer itself and by negative pressure produced after 
the impelling force. This phenomenon can cause problems in the operation 
of the equipment. 
Although the design has been known for more than 25 years and has had the 
preference of some investigators, many types of more complex and expensive 
by-pass valves were designed all over the world, but these are more easily 
obstructed. 
Through the accumulated and published experience it was known that the old 
"Pudenz" design continued to be preferred, but keeping in greater or 
lesser degree, as an undesirable eventuality, the collapsing failure 
during use. Many investigators tried, by using different designs on the 
inclusion of various devices, to avoid the eventual collapse in the 
original design, but giving up other advantages of the original valve and 
exposing the valve to damage of its inner structure when carrying out 
punctures that are usually made to obtain samples of the cephalorachidian 
liquid. This background constitutes the basis for the studies which led to 
the present invention. 
OBJECT OF THE INVENTION 
The present invention relates to improvements in the conventional pumping 
equipments (Pudenz type), which are a part of the drainage systems of the 
cephalorachidian liquid used for hydrocephalus treatment. The object of 
these improvements is to avoid the pump from collapsing during the digital 
compression that the patient or the doctor performs to accelerate the 
drainage or to displace coagulums.

DETAILED DESCRIPTION OF THE INVENTION 
As shown in FIG. 1, at the middle of the lower portion where piece A joins 
piece C, is the cylindrical chamber (E) in which diaphragm (D) is located. 
In that chamber E, said diaphragm reciprocates, passively actuated by 
pressure changes. If the pressure is greater in chamber F formed by domes 
(A and B), the diaphragm obstructs the central orifice where the brain 
drain drains, causing the liquid to flow through the drain going to the 
heart or to the peritoneum (I). On the contrary if the pressure is lower 
in chamber (F) the diaphragm rises and allows the liquid to flow towards 
the chamber. The orifice of device C cannot be obstructed by the diaphragm 
because device C has tooth-like projections that allow the flow of liquid 
and avoid the obstruction of the diaphragm. These conditions allow the 
device to operate as a reciprocating pump, sucking the cephalorachidian 
liquid from the brain and pumping it to the heart or to the peritoneum. 
The design as a whole forms a geometrical figure similar to a flat sphere 
having a flange on the position corresponding to the equator (See FIG. 1). 
It consists of four pieces: 
(A) A lower dome or base corresponding to the brain side manufactured from 
silicon rubber or other compatible material (see FIG. 1, letter A). 
(B) An impelling top dome corresponding to the opposite side manufactured 
also from the same material (See FIG. 1, letter B). 
(C) A circular-contour cup-shaped concave figure manufactured of a rigid 
plastic or any other material of similar consistency having at its lower 
middle portion an orifice surrounded by three teeth projecting downward. 
This portion assembles with another cylindrical chamber in the form of an 
empty cartridge which has an orifice in its base. (See FIGS. 1 and 2, 
letter K.) 
(D) A small diaphragm made of a rigid plastic material or any other 
material which operates as the element that obstructs the orifice during 
the impelling force. (See FIG. 1, letter D). It is located in the 
cylindrical chamber described in the previous paragraph. 
The object of this invention is to avoid the use of a mechanism formed by a 
veil or intermediate film of a resilient material which operates as the 
check valve during the impelling force at the pumping time; this system 
which has been traditionally used causes, as previously mentioned, certain 
anomalous operations when in use, for instance, it causes the impelling 
dome, which is also manufactured from a resilient material, when inverted 
under pressure to lie physically on the elastomeric film which acts as a 
check valve. This causes the closing of the suction orifice for the 
cephalorachidian liquid, thus causing the impellent dome B not to return 
to its original form due to the vacuum originated between this inverted 
dome B and the base of the pump, causing a suctioning effect. 
Although the dome collapse can be corrected in certain cases by itself due 
to the resilient proprieties of the dome, this correction is done 
progressively but slowly. Sometimes it is necessary to inject a sterile 
liquid into the pump to bring it to its original form. Although this 
anomaly is caused only by abnormal pressures during pumping, it interferes 
with the operation, with the resulting problems in the original design. 
In order to eliminate this sucking phenomenon which causes the collapse of 
the pump, the following device, which is the object of this patent 
application, has been developed. 
All pump types have an impelling mechanism and a check valve. 
In the present invention the check valve location and the design have been 
modified. This modification which is an improvement to the conventional 
design, avoids, as will be seen later, the collapse of the dome and 
protects the check valve against damages caused by needle punctures used 
sometimes to obtain cephalorachidian liquid samples. 
DESCRIPTION OF THE PREFERRED EMBODIMENT 
On the dome base A a rigid material cup is located; and on the lower and 
middle portion this cup ends in a chamber in the form of an empty 
cylindrical cartridge with a through orifice which communicates with the 
upper chamber. At the lower portion this chamber, which has an inner 
diaphragm, communicates directly with the brain drain. 
The check valve which is the subject matter of this invention, is located 
and protected by the rigid cup. When parts A and C are assembled together, 
a cylindrical chamber is integrated where the diaphragm is located. In 
that same structure the described through orifice is located and three 
teeth are projected downwards therefrom which are located around said 
orifice, positioned at 120.degree. from each other. These teeth do not 
allow the diaphragm to obstruct the orifice that connects chamber C and F 
of FIG. 1, thus allowing the free flow of liquid between both chambers. As 
it can be seen from the above the cylindrical chamber having the check 
valve is located at the cavity formed at the dome base while the upper 
portion is formed by the lower and middle section of the rigid cup. At the 
lower portion of this cavity there is the orifice which communicates to 
the brain drain and to a seat for supporting the diaphragm. 
This invention improves the operation of the conventional designs because 
it avoids the collapse of the impelling dome during operation, for it does 
not allow said dome to lie, when in an inverted position, on the check 
valve which does not exist anymore. The diaphragm is protected in a 
separate chamber; the rigid cup separates it from the dome, thus avoiding 
the pump to collapse, as previously described. 
On the other hand the check valve is not damaged by hypodermic needle 
punctures (which is a frequent operation in patients using these valves) 
due to the protection of the rigid material cup C.