The Epidemiology of Micro-arteriovenous Fistulas in the Lower Legs

Patients presenting with edema, skin redness, pain, and itching in their lower legs are common and encountered often in daily practice. However, although commonly recognized diseases such as deep venous thrombosis, stasis dermatitis due to varicose veins, lymphedema, and cellulitis are diagnosed correctly in most cases, micro-arteriovenous fistulas (AVFs) may often be overlooked due to low awareness and rarity. This study was carried out to evaluate the prevalence of micro-AVF in patients presenting with foot skin symptoms.

A total of 134 patients (184 limbs) visited the Department of Vascular Surgery at Kesennuma City Hospital with edema, skin redness, pain, and itching in their lower legs from January to September 2017 and were enrolled and followed up until November 2017. All patients received ultrasonic inspection of their symptomatic limb, and a blood test (white blood cell count, C-reactive protein, and d-dimer) was performed if needed. When micro-AVF was detected in one limb, the other limb was routinely inspected by ultrasonography. A computed tomography scan was performed with the patient's consent. Patients diagnosed with micro-AVF started compression therapy immediately and were followed up for at least 2 months. A surgical procedure was considered if the symptoms worsened.

Micro-AVFs were detected in 24 limbs (13%, 24/184) of 14 patients (7 males and 7 females; age 70 ± 11.7 years). Four patients had unilateral skin symptoms with unilateral micro-AVFs and 7 patients had unilateral skin symptoms and bilateral micro-AVFs. Three patients had bilateral skin symptoms and bilateral micro-AVFs. Asymptomatic micro-AVFs were detected in 7 limbs. Subjective symptoms disappeared and skin appearance normalized in 14 limbs of 12 patients during the first 2 months with compression therapy only. Compression therapy was not effective in 3 limbs of 2 patients and they underwent vein ligation surgery. None of the patients had a surgical history or history of trauma in their lower legs.

Among the lower legs presenting with skin symptoms, we detected micro-AVFs in 13% of limbs; therefore, micro-AVF of the lower leg is not as rare as previously thought. In addition, 10 of 14 patients (71%) had micro-AVFs of the lower leg bilaterally.