How is the arterial flow characterized proximal to an AVF?

When considering arterial flow proximal to an arteriovenous fistula (AVF), it is important to understand the physiological changes that occur due to the presence of the AVF.

The creation of an AVF leads to a direct connection between an artery and a vein, which significantly alters hemodynamics. Proximal to the AVF, blood flow patterns change, particularly resulting in increased diastolic flow. This happens because the AVF serves as a low-resistance pathway for blood, drawing more blood flow during diastole back into the adjacent artery. Essentially, the forward flow into the artery continues even during diastole, rather than fully stopping as might be expected in normal circumstances.

This change is critical in the context of vascular ultrasound, as it indicates the altered flow dynamics that can be expected near an AVF. Increased diastolic flow signifies that the artery is under the influence of the higher volume of blood returning to it from the AVF, which can be a marker for the adequacy of the AVF and the vascular system surrounding it. Understanding this concept is crucial for those involved in ultrasound vascular studies, as it assists with assessing the functionality and health of vascular access points, especially in patients undergoing hemodialysis