CPT code 37211 describes the initial day of transcatheter therapy for arterial thrombolysis. This procedure is a vital intervention for patients suffering from acute arterial occlusion, most commonly in the lower extremities (Acute Limb Ischemia), but also in other peripheral or visceral arteries excluding the heart and brain. The primary goal of the procedure is the pharmacologic dissolution of a thrombus or embolus to restore blood flow to distal tissues and prevent limb loss or organ failure. Technically, the procedure begins with percutaneous vascular access, typically through the common femoral artery using the Seldinger technique. Under fluoroscopic guidance, a specialized multi-perforated infusion catheter is navigated through the arterial system and embedded directly into or placed proximal to the clot. Once the catheter is optimally positioned, a thrombolytic agent—such as tissue plasminogen activator (tPA)—is administered, often starting with a bolus followed by a continuous low-dose infusion. This CPT code is comprehensive, meaning it incorporates the initial catheterization of the vessel, the administration of the thrombolytic drugs, and the necessary radiological supervision and interpretation (RS&I) performed throughout the first day. The physician must monitor the patient’s clinical status and may perform periodic angiography to evaluate the progress of the lysis. The work involves managing the infusion parameters and monitoring for complications such as hemorrhage or distal embolization of clot fragments. CPT 37211 is designated specifically for the first day of what is often a multi-day treatment course; subsequent days of infusion management or the conclusion of the therapy are reported with separate codes (37212-37214). It is important to note that the diagnostic angiography performed to identify the need for thrombolysis may sometimes be coded separately if a prior study hasn't been done or if the patient's condition has changed significantly.