Devices, systems and methods are disclosed for the formation of an arteriovenous fistula. Embodiments include catheter apparatus including an ablation element for creating and/or modifying the fistula. The devices, systems and methods can be used to treat patients with one or more numerous ailments including chronic obstructive pulmonary disease, congestive heart failure, hypertension, hypotension, respiratory failure, pulmonary arterial hypertension, lung fibrosis and adult respiratory distress syndrome.