A method of dissolving a thrombus in a blood vessel for improving blood flow. A filter device includes an expandable filter body fixed to a distal end portion of an outer catheter. The filter device also includes an agitation member disposed along a distal end portion of an inner catheter, wherein the inner catheter is slidably contained within the outer catheter. During treatment, the expandable filter body is expanded within the blood vessel and the inner catheter is advanced relative to the outer catheter such that the agitation member is positioned distal to the filter body. The agitation member is activated for dissolving the thrombus in the blood vessel. After the thrombus is at least partially dissolved, aspiration is applied for pulling resulting particles into the filter body. The filter device is then retracted into a delivery sheath with the particles captured inside the filter body.
