Declotting dialysis catheter in OP Infusion Center

In our Outpatient Infusion Center, we occasionally have a patient present for declotting of his dialysis catheter; receiving alteplase in a two-hour infusion. No imaging is performed. Would this still be coded as 36593; or would there be a more appropriate CPT® code to capture the lengthy infusion?

Thank you!!
Kathy
Coder II, Cancer Program
Outpatient Infusion