What happens to the pressure in the artery distal to an arteriovenous fistula?

When an arteriovenous fistula is created, it directly connects an artery to a vein, bypassing the capillary system. This connection leads to changes in the hemodynamics of the vessel. In a healthy circulatory system, arterial blood pressure is typically maintained due to the resistance offered by the capillary beds. However, with a fistula, the blood flows directly from the artery into the vein, which has a significantly lower resistance.

As a result of this direct connection, the pressure in the artery distal to the fistula is reduced. This occurs because the blood is allowed to flow preferentially into the low-resistance pathway of the vein, causing a drop in pressure within the distal arterial segment. The reduced pressure is essentially a byproduct of the high volume of blood flowing through the fistula, which diverts blood away from the normal arterial pathway and lowers the pressure before it reaches that point.

Understanding this mechanism is crucial for patients with arteriovenous fistulas, particularly those undergoing dialysis, as it impacts vascular health and can influence the approach to patient management and care.