Intimal Hyperplasia, Stenosis, and Arteriovenous Fistula Maturation Failure in the Hemodialysis Fistula Maturation Study

Abstract

Intimal hyperplasia and stenosis are often cited as causes of arteriovenous fistula maturation failure, but definitive evidence is lacking. We examined the associations among preexisting venous intimal hyperplasia, fistula venous stenosis after creation, and clinical maturation failure. The Hemodialysis Fistula Maturation Study prospectively observed 602 men and women through arteriovenous fistula creation surgery and their postoperative course. A segment of the vein used to create the fistula was collected intraoperatively for histomorphometric examination. On ultrasounds performed 1 day and 2 and 6 weeks after fistula creation, we assessed fistula venous stenosis using pre-specified criteria on the basis of ratios of luminal diameters and peak blood flow velocities at certain locations along the vessel. We determined fistula clinical maturation using criteria for usability during dialysis. Preexisting venous intimal hyperplasia, expressed per 10% increase in a hyperplasia index (range of 0%-100%), modestly associated with lower fistula blood flow rate (relative change, -2.5%; 95% confidence interval [95% CI], -4.6% to -0.4%; P=0.02) at 6 weeks but did not significantly associate with stenosis (odds ratio [OR], 1.07; 95% CI, 1.00 to 1.16; P=0.07) at 6 weeks or failure to mature clinically without procedural assistance (OR, 1.07; 95% CI, 0.99 to 1.15; P=0.07). Fistula venous stenosis at 6 weeks associated with maturation failure (OR, 1.98; 95% CI, 1.25 to 3.12; P=0.004) after controlling for case mix factors, dialysis status, and fistula location. These findings suggest that postoperative fistula venous stenosis associates with fistula maturation failure. Preoperative venous hyperplasia may associate with maturation failure but if so, only modestly.

Figure 1.

Prevalence and transitions of ultrasound-detected stenoses at three different time points after AVF creation. Black boxes represent participants in whose AVFs one or more stenoses were detected, and white boxes represent those without detected stenosis. Numbers in black boxes are percentages with stenosis (prevalence) among all participants who underwent the ultrasound examination at the time point indicated on the left. Those in white boxes are the percentages of stenosis-free participants. Numbers adjacent to arrows are percentages of participants in the higher box who transitioned to the lower box on the next ultrasound from data on all participants who underwent both examinations. Black arrows indicate stenosis development or persistence, whereas white arrows indicate continued absence or resolution of stenosis.

Figure 2.

Timeline of study procedures. Preoperative ultrasound for mapping of the arteries and veins was performed preferably within 45 days of the AVF creation surgery and needed to be within 90 days of the surgery. Postoperative ultrasounds of the AVF were performed at 1 day, 2 weeks, and 6 weeks.