Pressure responsive valve catheter

Claim 1

A catheter for introducing material into the vascular system comprising: an elongated catheter body having a sidewall defining a catheter lumen, said catheter body having a proximal portion with means through which material is introduced into the catheter lumen and a distal portion from which material can exit from said catheter lumen; said catheter having an occluded distal end; said distal portion being proximal of said distal end and capable of assuming an open position and a closed position, said distal portion when in its open position allowing fluid to exit from said catheter lumen, said distal portion when in its closed position preventing material from exiting from said catheter lumen, said distal portion moving from its closed position to its open position in response to fluid pressures equal to or greater than a predetermined internal fluid pressure, said distal portion serving as a pressure responsive exit to deliver material to the vascular system; and adjusting means for adjusting the predetermined internal fluid pressure necessary to move said distal portion from its closed position to its open position, said adjusting means including a pre-loaded spring and connecting means for connecting said pre-loaded spring to said distal end, said connecting means transmitting forces between said pre-loaded spring and said distal end said pre-loaded spring holding said distal portion in its closed position in the absence of said predetermined internal fluid pressure, said pre-loaded spring automatically causing said distal portion to return to its closed position in the absence of said predetermined internal fluid pressure; said distal portion being formed such that it does not move from its closed position to its open position in response to a pressures equal to or less than a predetermined external fluid pressure.