[High-flow fistula: a problem not easy to handle].

Area of Science:

• Nephrology
• Cardiology
• Vascular Surgery

Background:

• High-output cardiac failure is a recognized complication in hemodialysis patients with high-flow arteriovenous fistulas (AVF).
• The definition of "high flow" in AVF is inconsistent, but it significantly impacts hemodynamics and can compromise circulatory function, especially in elderly patients with pre-existing heart conditions.
• Associated complications include pulmonary hypertension, central vein stenosis, and dialysis-associated steal syndrome.

Approach:

• This study reviews the pathophysiology of high-flow AVF, emphasizing the shunting of blood from arterial to venous systems, increasing venous return and potentially leading to cardiac failure.
• It highlights the need for accurate and timely diagnosis through monitoring of fistula blood flow and cardiac function.
• Two case studies of patients with high-flow AVF are presented alongside a literature review.

Key Points:

• There is no universally accepted threshold for defining high-flow AVF, though rates of 1-1.5 L/min are suggested.
• AVF flow is considered excessive if signs of cardiac failure develop, regardless of specific numerical values.
• Pathophysiology involves increased venous return due to arterial-venous shunting, potentially overwhelming cardiac capacity.

Conclusions:

• Early detection of high-flow AVF and its hemodynamic effects is essential to prevent the progression to high-output cardiac failure.
• Monitoring fistula blood flow and cardiac status is critical for managing patients at risk.
• Further research is needed to establish standardized definitions and diagnostic criteria for high-flow AVF.