Similar degree of intimal hyperplasia in surgically detected stenotic and nonstenotic arteriovenous fistula segments: a preliminary report

Abstract

Background: Intimal hyperplasia has been historically associated with improper venous remodeling and stenosis after creation of an arteriovenous fistula. Recently, however, we showed that intimal hyperplasia by itself does not explain the failure of maturation of 2-stage arteriovenous fistulas. We seek to evaluate whether intimal hyperplasia plays a role in the development of focal stenosis of an arteriovenous fistula.

Methods: This study compares intimal hyperplasia lesions in stenotic and nearby nonstenotic segments collected from the same arteriovenous fistula. Focal areas of stenosis were detected in the operating room in patients (n= 14) undergoing the second-stage vein transposition procedure. The entire vein was inspected, and areas of stenosis were visually located with the aid of manual palpation and hemodynamic changes in the vein peripheral and central to the narrowing. Stenotic and nonstenotic segments were documented by photography before tissue collection (14 tissue pairs). Intimal area and thickness, intima-media thickness, and intima to media area ratio were measured in hematoxylin and eosin stained cross-sections followed by pairwise statistical comparisons.

Results: The intimal area in stenotic and nonstenotic segments ranged from 1.25 to 11.61 mm² and 1.29 to 5.81 mm², respectively. There was no significant difference between these 2 groups (P=.26). Maximal intimal thickness (P=.22), maximal intima-media thickness (P=.13), and intima to media area ratio (P=.73) were also similar between both types of segments.

Conclusion: This preliminary study indicates that postoperative intimal hyperplasia by itself is not associated with the development of focal venous stenosis in 2-stage fistulas.

Figure 1

Photograph of a first-stage brachiobasilic arteriovenous fistula demarcating the locations of the focal stenotic (yellow dashed lines) and non-stenotic segments (red dashed lines) in the outflow segment.

Figure 2

Representative hematoxylin and eosin-stained cross-sections of native veins (left panel) before anastomosis and segments of the resulting arteriovenous fistulas (AVF; right panel) at the time of transposition. Native veins present a low-moderate degree of pre-existing intimal hyperplasia (IH), whereas AVFs show moderate-severe postoperative IH. Focal stenotic and nearby non-stenotic segments from the same AVF present a similar degree of IH. I: intima, M: media. Distances are in μm.

Figure 3

Pairwise comparison of intimal hyperplasia, expressed as intima to media area ratio, in focal stenotic and nearby non-stenotic segments from the same arteriovenous fistula (AVF; p=0.73). The asterisks indicate AVFs with maturation failure.