Flow reduction of a high-flow arteriovenous fistula in a hemodialysis patient reveals changes in natriuretic and renin-angiotensin system hormones of relevance for kidney function.

Arteriovenous fistulas (AVFs) are iatrogenic vascular connections established to allow high-flow intravascular access for patients with chronic kidney disease requiring hemodialysis. The left-right flow shunt results in changes in extracellular fluid volume and blood pressure-controlling hormones that could affect the residual kidney function. We present a case where a female patient with a brachiocephalic AVF had a fistula flow of >4 L/min. To reduce the flow, a banding procedure was performed. The patient was examined prior to banding and 1 and 2 weeks thereafter. Banding resulted in a marked decrease in AVF flow from >4 to 1 L/min and was associated with reductions in N-terminal pro-brain natriuretic peptide of 51% and 67% at 1- and 2-weeks post-banding, respectively. Mid-regional pro-atrial natriuretic peptide concentrations were reduced post-banding by 17% after 1 week and 25% after 2 weeks. After 1 week, renin, angiotensin II, and aldosterone levels in plasma decreased transiently by 44%, 47%, and >86%, respectively, and returned to pre-banding levels after 2 weeks. Creatinine clearance tended to decrease while blood pressure and total body water increased 2 weeks after banding. This indicates that high-flow AVF is associated with increased natriuretic peptides and hormones of the renin-angiotensin-aldosterone system, that may balance each other regarding fluid retention and hypertension and support remaining kidney function.