Potential fistula-related problems which may impact on patient survival include high fistula flow with hyperkinetic circulation and cardiac failure, low fistula flow with the risks of underdialysis and fistula thrombosis, vascular access infection with local or systemic manifestations, and possibly induction and maintenance of a microinflammatory state (at least for synthetic grafts). All these complications are much more common with prosthetic grafts than with native arteriovenous (AV) fistulas. Fistula flow should be monitored (e.g., by duplex sonography) to guarantee adequate flow and permit preemptive intervention to avoid fistula thrombosis.