Background: This study investigated the outcomes of the distal facial vein catheterization (DFVC) to manage venous thrombosis in vascularized submental lymph nodes (VSLN) flap transplantations. Methods: Between March 2017 and December 2020, patients who underwent VSLN flaps were divided into Group I: combined delayed primary retention sutures (DPRS) with DFVC, and Group II: DPRS alone. Primary outcomes were early (within 72 h) and late venous thrombosis. Secondary outcomes included other nonvascular complications and mechanical factors of the thrombosis.Results: A total of 105 patients who underwent 106 VSLN flaps, including 37 and 69 flaps in Groups I and II, respectively, were included. There were no statistically significant differences in age, body mass index, Taiwan lymphoscintigraphy staging, and surgical factors between the two groups (all p > 0.05). Early venous thrombosis requiring re-exploration developed in one (2.7%) and three (4.3%) flaps in Groups I and II, respectively (p = 0.20). One flap (2.7%) and eight (11.5%) flaps developed late venous thrombosis in Groups I and II, respectively (p < 0.01). There was no statistically significant difference in total complication rates between both groups (p = 0.9). Conclusion: VSLN flap transplantation had a significantly higher risk of late venous thrombosis. DFVC significantly decreased the late venous thrombosis. K E Y W O R D S free tissue transfer, lymphedema, venous thrombosis, VLNT 1 | INTRODUCTION Extremity lymphedema is a chronic and progressive disease that can immensely hamper a patient's functionality and quality of life.

Summary: Arterialized tissues provide longevity and coverage of critically exposed tissue, and in pliable areas of the body, thin flaps are needed. Arterialized venous flaps provide all the aforementioned qualities, yet unpredictability in flap perfusion requires further investigation in experimental studies. Existing animal models are thicker in nature and rarely mimic commonly used venous flaps in clinical practice. A novel design of the rat’s tail provides an ideal model for arterialized venous flaps. Eleven venous flaps were harvested from the rats’ tail, all presenting with two parallel veins in configuration. Arterialization of veins using the femoral artery was done in either along-valve or against-valve fashion, with the purpose of testing the flap’s response to different clinical configurations. The vessel diameter and flap thickness were measured. Flap viability was monitored for 7 days after surgery to ensure stable flap viability. Thickness of the tail flap ranged from 1.0 to 1.2 mm, while the abdomen skin thickness ranged from 1.4 to 1.5 mm. The mean diameter of the lateral veins was 0.85 ± 0.08 mm, which was in between the average femoral artery diameter (mean 0.76 ± 0.1 mm) and the average femoral vein diameter (1.28 ± 0.2 mm). Four of the nine against-valve flaps achieved more than 50% flap survival, while all along-valve flaps achieved flap viability of more than 75%, as evident by indocyanine green imaging. This flap demonstrates similar properties to thin venous flaps used in clinical situations. Standardization of this model can push forth better understanding of the arterialization phenomenon in venous flaps for future studies.