Balloon catheter with valve

Claim 1

A balloon catheter for performing a medical treatment on a patient, comprising: a flexible shaft, with a tubular basic body having distal and proximal ends, and defining an inflation lumen extending between the ends; the shaft defining a purge port; a balloon affixed to the shaft near the distal end, such that the balloon communicates with the inflation lumen; the balloon having an inflated state and a deflated state; a valve communicating with the inflation lumen, selectively operable between a first open position, a second intermediate position, and a third closed position; such that the valve in the open position allows fluid flow from the proximal end through the inflation lumen, through the balloon, and out the purge port to purge the catheter; the valve in the intermediate position partially closes to block fluid flow from inside the balloon to the purge port, while allowing fluid communication between the proximal end and the balloon through the inflation lumen to selectively inflate or deflate the balloon; and the valve in the closed position isolates the balloon by closing it off from the inflation lumen and the purge port, to maintain a constant pressure inside the balloon.