Closed tip dynamic microvalve protection device

A method of operating a microvalve device to infuse a therapeutic agent in a blood vessel, comprising:

• a) advancing the microvalve device in the blood vessel, the microvalve device comprising,
• i) a flexible outer catheter having a proximal end and a distal end,
• ii) a flexible inner catheter having a proximal end and a distal end, the inner catheter having an infusion lumen with a distal orifice, the infusion lumen adapted for delivery of the therapeutic agent, the inner catheter extending through and longitudinally displaceable relative to the outer catheter, an annular space formed between the inner and outer catheters,
• iii) a filter valve having a proximal end and distal end, the proximal end of the filter valve coupled to the distal end of the outer catheter, and the distal end of the filter valve coupled to the inner catheter adjacent the distal end of the inner catheter, such that longitudinal displacement of the inner catheter relative to the outer catheter permits the filter valve to be reconfigured from a collapsed configuration to an expanded configuration, the filter valve having an interior space defined between an interior surface of the filter valve and an exterior surface of the inner catheter, the interior space in fluid communication with the annular space,
• iv) a port in fluid communication with the annular space and the interior space,
• v) a first radio-opaque marker located on the distal end of the flexible inner catheter,
• vi) a second radio-opaque marker located on the distal end of the flexible outer catheter, and
• vii) a third radio-opaque marker located on the flexible inner catheter and longitudinally displaceable relative to the second radio-opaque marker such that a decrease in a distance between the second radio-opaque marker and the third radio-opaque marker corresponds to the filter valve being reconfigured from the collapsed configuration to the expanded configuration, and
• wherein the filter valve is in the collapsed configuration as the microvalve device is advanced in the blood vessel;
• b) expanding the filter valve to increase a pressure differential in the blood vessel between proximal and distal sides of the filter valve;
• c) flushing the annular space including the interior space with a lubricating fluid;
• and
• d) infusing the therapeutic agent through the infusion lumen while the pressure differential is increased by expansion of the filter valve.