Ultrasound-Guided Direct Thrombolytic Injection for Acute and Early-Subacute Arterial Occlusions: Feasibility and Early Outcomes.

purposeTo evaluate the feasibility, technical success, and safety of ultrasound (US)-guided direct thrombolytic injection in patients with acute and early-subacute extremity arterial occlusions. MATERIALS AND

methodsThis retrospective, single-center study included 24 patients treated between July 2023 and January 2025 for acute (≤14 days) or early-subacute (14-21 days) arterial occlusions (Rutherford I-IIb). Under real-time US guidance, alteplase (2-10 mg total) was injected into the thrombus at 2 to 3 cm intervals using a 27-gauge (40-mm) or, for deeper targets, a 22-gauge (90-mm) needle. Doppler US was performed at 2, 4, and 6 hours to assess recanalization. The primary endpoint was Doppler US-based recanalization category at 6 hours (complete/partial/none) prior to any adjunct endovascular revascularization. Secondary endpoints included adjunct angiography/endovascular procedures, complications, and follow-up primary-assisted and secondary patency at 1, 3, and 6 months.

resultsAt 6 hours, complete recanalization was observed in 12/24 (50.0%), partial in 4/24 (16.7%), and no recanalization in 8/24 (33.3%). The median alteplase dose was 6 mg (range, 2-10 mg). Diagnostic angiography was performed in 15/24 (62.5%), and adjunct endovascular procedures were performed as indicated. Minor complications occurred in 10/24 (41.7%); no major bleeding or procedure-related mortality occurred. Two patients with Rutherford IIb ischemia and symptom duration >14 days ultimately underwent major amputation after refusing further revascularization. Primary-assisted patency rates were 66.7%, 58.3%, and 41.7%, and secondary patency rates were 87.5%, 79.2%, and 75.0% at 1, 3, and 6 months, respectively. In multivariable ordinal regression, shorter time to alteplase administration was independently associated with a more favorable 6-hour Doppler recanalization category (OR 15.67; 95% CI, 1.88-130.59; p=0.011), with wide confidence intervals indicating limited precision.

conclusionsUS-guided direct intrathrombus alteplase injection appears feasible with an acceptable safety profile and provides an early Doppler-defined response in selected patients. Prospective comparative studies are needed to define its role and refine patient selection.Clinical ImpactUltrasound-guided direct intrathrombus alteplase injection is a feasible, minimally invasive option for selected patients with acute and early-subacute arterial occlusions. The innovation is localized, real-time US-targeted delivery of low-dose tPA without catheter placement or prolonged infusion, combined with serial Doppler assessment to guide repeat dosing and timely escalation to angiography and adjunct endovascular therapy when indicated. For clinicians, this provides a practical workflow with close non-ICU monitoring, enabling early identification of residual thrombus, distal embolization, or underlying stenosis. The study also reinforces that shorter symptom duration strongly influences early recanalization.