AV Access: A Blessing or a Curse?

There is general consensus that the AV fistula is the preferred vascular access for end-stage renal disease patients undergoing hemodialysis. The AV fistula has been associated with reduced hospitalizations for AV access failure, fewer missed treatments, fewer invasive surgical procedures, fewer infections and reduced costs compared with vascular access grafts or catheters. On the Fistula First/Catheter Last website, the arteriovenous fistula is called the “Lifeline for a Lifetime.”

Yet, an AVF does not come without certain problems. First, the AV fistula has to mature before it can be used. Lack of maturation is common, which means a patient might have to resort to a catheter. Moreover, Italian nephrologist Carlo Basile notes: “Cardiovascular events are the major cause of death in hemodialysis patients with more than 50% of patients on hemodialysis dying from some form of cardiovascular disease. While it is recognized that the presence of an AVF has an adverse effect on cardiac function, but its exact contribution to CV morbidity is not clear.”

An AVF is, in effect, a left-to-right extracardiac shunt. Cardiac output (CO) increases greatly and immediately on opening an AVF in experimental models. This increase in CO is achieved by means of a reduction in peripheral resistance, an increase in sympathetic nervous system activity (increasing contractility) and an increase in stroke volume and heart rate to maintain blood pressure. With time, excess cardiac stimulation leads to LVH, reduction in LV ejection fraction and eventual heart failure.

The main message in a review by Dr. Richard Amerling was “The AVF is a non-physiological anomaly and should be considered a lesser evil … undoubtedly contributes to excess CV mortality in HD patients and shortens lifespans.”

Is AVF a lesser evil or a blessing of God? Basile insists that the right answer is the second. He points out that Amerling’s review ignores the life-saving benefit of an AVF for millions of human beings with end-stage renal disease. However, while emphasizing the real benefits of creating a native AVF, Basile warns not to overlook the danger of excessive fistula blood flow rates.

A “patient first, not fistula first,” is Basile’s advice with the nephrologist becoming the designated coordinator of a vascular access team.

References

Basile C, Lomonte C, “Pro: the arteriovenous fistula is a blessing of God.” Nephrol Dial Transplant. 2012 Oct;27(10):3752-6.

Basile C, Lomonte C, Konner K, “The Arteriovenous fistula: lesser evil or God's blessing?” Blood Purif. 2011;32(4):253.

Amerling R, Ronco C, Kuhlmann M, et al, “Arteriovenous fistula toxicity.” Blood Purif 2011;31:113-120.