How do arteriovenous fistulas (AVFs) contribute to heart failure?

From the Guidelines

Fistulas can cause heart failure by creating abnormal connections between blood vessels, leading to increased cardiac workload and eventual heart failure, as seen in cases of high-output cardiac failure due to liver arteriovenous fistulas 1. When a fistula forms, it creates a pathway that allows blood to bypass normal circulation, often creating a left-to-right shunt where oxygenated blood returns to the lungs instead of circulating to the body. This forces the heart to pump more blood to maintain adequate systemic circulation, resulting in volume overload. The heart compensates initially by increasing cardiac output, but over time, this chronic overload causes the heart chambers to dilate and the heart muscle to hypertrophy. Some key points to consider include:

• The size and location of the fistula play a significant role in determining the severity of the hemodynamic effects, with larger fistulas causing more significant effects.
• Treatment options, such as transarterial embolization or orthotopic liver transplantation, have been proposed for liver arteriovenous fistulas, with the main indication being high-output cardiac failure 1.
• The American College of Cardiology/American Heart Association guidelines recommend closing large coronary artery fistulas, regardless of symptomatology, via either a transcatheter or surgical route 1. The most effective treatment approach is to close the fistula through surgical repair or catheter-based interventions to restore normal blood flow patterns and reduce cardiac strain, as recommended by the ACC/AHA guidelines 1.

From the Research

Causes of Heart Failure due to Fistulas

• Fistulas can cause heart failure by increasing the workload on the heart, leading to cardiac hypertrophy and eventual heart failure 2, 3, 4, 5
• High-output heart failure can occur when a large proportion of arterial blood is shunted from the left-sided circulation to the right-sided circulation via the fistula, increasing preload and cardiac output 2
• The increase in cardiac output can lead to cardiac hypertrophy and eventual heart failure, with patients presenting with symptoms such as tachycardia, elevated pulse pressure, hyperkinetic precordium, and jugular venous distension 2

Types of Fistulas that can Cause Heart Failure

• Coronary artery fistulas (CAFs) are rare coronary anomalies that can lead to clinical sequelae such as cardiac chamber enlargement or myocardial ischemia, and can increase the risk of heart failure 6, 5
• Arteriovenous fistulas (AVFs) can also cause heart failure, particularly high-flow AVFs, which can lead to high-output cardiac failure (HOCF) 2, 3, 4
• The risk of heart failure due to AVFs can be increased in patients with advanced kidney disease, who already have a high burden of cardiovascular risk 3

Diagnosis and Treatment of Heart Failure due to Fistulas

• Diagnosis of heart failure due to fistulas can be made using echocardiography, which can reveal left ventricular hypertrophy, diastolic dysfunction, and increased cardiac output 4
• Treatment of heart failure due to fistulas can involve surgical banding or ligation of the fistula, which can help to reduce the workload on the heart and prevent progression of heart failure 2, 3
• Indexation of AVF blood flow can help to identify patients at higher risk of HOCF, and echocardiographic alterations can also be used to identify patients at higher risk 4