Shunt valve

In a surgically implantable shunt system in which cerebrospinal fluid is vented from a cerebroventricular catheter to a drainage catheter, a valve for presenting a precisely controllable back pressure to the ventricles, said valve comprising:

• an elongate, hollow valve body;
• a flat plate partitioning said valve body so as to form an inlet chamber and an outlet chamber, said ventricular catheter being coupled to said inlet chamber and said drainage catheter being coupled to said outlet chamber, said plate being provided with a circular aperture connecting said inlet and outlet chambers;
• a spherical ball of diameter larger than said aperture for controllably restricting flow through said aperture;
• a spring including a cantilevered flat portion overlying said ball and biasing it against the circular periphery of said aperture whereby a circular seal is selectively effected between said ball and said plate, providing a precisely defined back pressure with low hysteresis and low susceptibility to bridging by debris;
• wherein said spring comprises a first portion overlying said ball and a second portion having a first and a second end, said second end adapted for attachment to said flat plate, wherein said first spring portion is attached to said second spring portion near said second end, and screw means supported in said flat plate and adapted for engaging said first end of said second spring portion whereby the opening pressures of said valve can be adjusted.

In a surgically implantable shunt system in which cerebrospinal fluid is vented from a cerebroventricular catheter to a drainage catheter, a valve for presenting a precisely controllable back pressure to the ventricles, said valve comprising:

• an elongate, hollow valve body;
• a flat plate partitioning said valve body so as to form an inlet chamber and an outlet chamber, said ventricular catheter being coupled to said inlet chamber and said drainage catheter being coupled to said outlet chamber, said plate being provided with a circular aperture connecting said inlet and outlet chambers;
• a spherical ball of diameter larger than said aperture for controllably restricting flow through said aperture;
• a spring including a cantilevered flat portion overlying said ball and biasing it against the circular periphery of said aperture whereby a circular seal is selectively effected between said ball and said plate, providing a precisely defined back pressure with low hysteresis and low susceptibility to bridging by debris;
• wherein said spring comprises a first portion overlying said ball and a second portion including a semicircular bend, the lower portion of said second portion affixed to said flat plate and said first portion of said spring attached to the upper surface of said second portion, and screw means supported by said flat plate adapted to engage said second portion for adjusting the opening pressure of said valve.

In a surgically implantable shunt system in which cerebrospinal fluid is vented from a cerebroventricular catheter to a drainage catheter, a valve for presenting a precisely controllable back pressure to the ventricles, said valve comprising:

• an elongate, hollow valve body;
• a flat plate partitioning said valve body so as to form an inlet chamber and an outlet chamber, said ventricular catheter being coupled to said inlet chamber and said drainage catheter being coupled to said outlet chamber, said plate being provided with a circular aperture connecting said inlet and outlet chambers;
• a spherical ball of diameter larger than said aperture for controllably restricting flow through said aperture;
• and
• a spring assembly overlying said ball and biasing it against the circular periphery of said aperture whereby a circular seal is selectively effected between said ball and said plate, said spring assembly comprising a central portion extending from a rear end thereof and adapted for overlying said ball and a pair of arms flanking said central portion and extending from said rear end, the ends of said arms adapted for attachment to said flat plate, and screw means supported by said flat plate and adapted for engaging said rear end of said spring assembly whereby the opening pressure of said valve can be accurately adjusted.

In a surgically implantable shunt valve including a ball biased against a hole in a flat plate to effect a seal,

• means for biasing said ball against said flat plate comprising:
• a first spring means having one end affixed to said flat plate;
• a second spring means affixed to the other end of said first spring means and adapted for overlying said ball;
• and
• means for adjusting the biasing force comprising screw means threadably supported by said flat plate and adapted for engaging said other end of said first spring means;
• the compliances of said first and second spring means and their respective lengths selected to provide low sensitivity of change in said bias force with the position of said screw means.