Recent advances in the diagnosis and treatment of renal arteriovenous malformations and fistulas

Arteriovenous malformations remain relatively rare clinical lesions. However, with an increasing number of percutaneous renal procedures being performed, their overall incidence can be expected to increase. Congenital arteriovenous malformations usually present with hematuria, while acquired fistulas are more likely to present with hemodynamic changes, such as hypertension, cardiomegaly and congestive heart failure. Arteriography remains the principal method of diagnosis. However, newer imaging modalities such as CT, MRI and color duplex ultrasound may make significant contributions in the evaluation of these abnormalities (fig. 1). Surgery, whether nephrectomy or ligation of feeding vessels, has long been the standard treatment for symptomatic arteriovenous malformations or fistulas. The loss of normal renal parenchyma, migration of occluding agents or recanalization of abnormal vessels has limited the use of embolization as a method of treatment in the past. Recently, newer techniques and agents, such as pharmacoangiography and alcohol, have increased the efficacy of embolization therapy, either as an adjuvant to surgery, definitive therapy or palliation. Although to our knowledge there have been no controlled studies comparing surgical treatment versus embolization, certain recommendations can be made. Because of the decreasing morbidity and increasing efficacy, embolization should be attempted at the time of arteriography as a means of treatment for most arteriovenous malformations and fistulas. However, the choice of surgery, embolization or a combination must be individualized for each patient with regard to overall health, symptoms and manifestations of the fistula or malformation (fig. 2).