Closed tip dynamic microvalve protection device

A method of a using a microvalve device in a blood vessel, comprising:

• a) advancing a guidewire through the blood vessel;
• b) providing the microvalve device including,
• 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 with an orifice, the inner catheter extending through and longitudinally displaceable relative to the outer catheter, and
• iii) a filter valve having a proximal end and a 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 at a location spaced proximal relative to the distal end of the inner catheter such that the inner catheter protrudes beyond the filter valve, wherein longitudinal displacement of the inner catheter relative to the outer catheter causes the filter valve to reconfigure from a non-deployed configuration to a deployed configuration;
• c) with the distal end of the inner catheter longitudinally advanced a first distance relative to the distal end of the outer catheter such that the filter valve assumes a first diameter, advancing the filter valve over the guidewire;
• d) once the filter valve reaches a target location, the distal end of the inner catheter is retracted relative to the distal end of the outer catheter such that the distal end of the inner catheter is longitudinally advanced by a second distance smaller than the first distance relative to the distal end of the outer catheter such that the filter valve assumes a second diameter larger than the first diameter;
• e) subsequent to d), further retracting the distal end of the inner catheter relative to the distal end of the outer catheter such that the distal end of the inner catheter is longitudinally advanced by a third distance relative to the distal end of the outer catheter to cause at least a distal portion of the filter valve to invert into the outer catheter and cause the filter valve to have a planar or a concave distal face while the distal end of the inner catheter protrudes beyond both the filter valve and the outer catheter;
• and
• f) infusing a therapeutic agent through the microvalve device, out of the orifice of the inner catheter, and beyond the filter valve.