Acquired Arterio-Venous Fistula Following Deep Vein Thrombosis

Deep vein thrombosis (DVT) is a serious condition, and if left untreated, it can lead to a pulmonary embolism. In patients with chronically occluded veins, other symptoms can develop, often grouped under the diagnosis of post-thrombotic syndrome (PTS). This case study describes the unusual finding of an acquired arterio-venous fistula (AVF) following a left leg DVT in a 78-year-old male patient. The patient had a history of previous DVT and multiple comorbidities, which may have contributed to his presenting symptoms of left leg swelling and pain. However, an unexpected connection between the sapheno-femoral junction and common femoral artery was identified with ultrasound, consistent in appearance with an AVF. The patient had no history of vascular injury or access in the groin. A literature review identified a retrospective study and 4 case reports describing similar clinical presentations, and further analysis highlighted the potential benefits of venous stenting in symptomatic patients. However, the mechanism of action for the formation of an AVF following DVT is unclear. One such factor that could explain this phenomenon is vascular endothelial growth factor (VEGF), which upregulates angiogenesis. In an occluded vessel, VEGF is dysregulated and may provide an explanation for the development of an AVF following DVT. This case study aims to raise awareness of the development of AVF in patients with a history of DVT. Our case shows that an acquired AVF can arise in patients without a history of vascular access or iatrogenic injury and may be potentially missed in patients diagnosed with PTS. The use of pulse wave Doppler in addition to compression and colour Doppler was key to identifying the AVF and providing important haemodynamic information.