Preoperative Arterial Microcalcification and Clinical Outcomes of Arteriovenous Fistulas for Hemodialysis

Abstract

Background Arteriovenous fistulas (AVFs) often fail to mature, but the mechanism of AVF non-maturation is poorly understood. Arterial micro-calcification is common in patients with chronic kidney disease (CKD), and may limit vascular dilatation, thereby contributing to early postoperative juxta-anastomotic AVF stenosis and impaired AVF maturation. This study evaluated whether preexisting arterial micro-calcification adversely affects AVF outcomes. Study Design Prospective study. Setting & Participants 127 patients with CKD undergoing AVF surgery at a large academic medical center. Predictors Preexisting arterial micro-calcification (≥1% of media area) assessed independently by von Kossa stains of arterial specimens obtained during AVF surgery and by preoperative ultrasound. Outcomes Juxta-anastomotic AVF stenosis (ascertained by ultrasound obtained 4-6 weeks postoperatively); AVF non-maturation (inability to cannulate with 2 needles with dialysis blood flow ≥300 ml/min for ≥6 sessions in 1 month within 6 months of AVF creation); and duration of primary unassisted AVF survival after successful use (time to first intervention). Results Arterial micro-calcification was present by histology in 40% of patients undergoing AVF surgery. The frequency of a postoperative juxta-anastomotic AVF stenosis was similar in patients with or without preexisting arterial micro-calcification (32% vs 42%; OR, 0.65; 95% CI, 0.28-1.52; p=0.3). AVF non-maturation was observed in 29%, 33%, 33%, and 33% of patients with <1%, 1%-4.9%, 5%-9.9%, and ≥10% arterial micro-calcification, respectively (p=0.9). Sonographic arterial micro-calcification was found in 39% of patients and was associated with histologic calcification (p=0.001), but did not predict AVF non-maturation. Finally, among AVFs that matured, the unassisted AVF maturation (time to first intervention) was similar for patients with and without preexisting arterial micro-calcification (HR, 0.64; 95% CI, 0.35-1.21; p=0.2). Limitations Single center study. Conclusions Arterial micro-calcification is common in patients with advanced CKD, but does not explain postoperative AVF stenosis, AVF non-maturation, or AVF failure after successful cannulation.

New Insights into Dialysis Vascular Access: Impact of Preexisting Arterial and Venous Pathology on AVF and AVG Outcomes

“…In contrast, using histologic analysis, preexisting microcalcification in arteries used for AVF creation did not predict postoperative stenosis, AVF maturation, or primary unassisted patency (38,50). Arterial macrocalcification, as determined by preoperative ultrasound, correlated well with arterial microcalcification and was also not associated with AVF nonmaturation (50). This study, however, excluded patients with severe concentric calcification, which is better detected by plain radiographs.…”

“…Calcification severity in patients on hemodialysis with working AVFs as determined by radiology correlated with worse AVF patency in a 5-year follow-up study (49). In contrast, using histologic analysis, preexisting microcalcification in arteries used for AVF creation did not predict postoperative stenosis, AVF maturation, or primary unassisted patency (38,50). Arterial macrocalcification, as determined by preoperative ultrasound, correlated well with arterial microcalcification and was also not associated with AVF nonmaturation (50).…”

New Insights into Dialysis Vascular Access: What Is the Optimal Vascular Access Type and Timing of Access Creation in CKD and Dialysis Patients?

“…However, data from the Hemodialysis Fistula Maturation Study reveal that noncompliant feeding arteries are associated with a lower incidence of early thrombosis (57). Arterial microcalcification itself may not be associated with maturation failure (62,63) if the artery is of adequate size and overall quality to allow for surgical proximal and distal control and suture placement.…”

Pre-existing arterial microcalcification and arteriovenous fistula failure

“…While Choi et al [2] found an association between pre-existing arterial microcalcification of the vascular access and AVF failure, Allon et al [3] reported that neither AVF nor arteriovenous graft survival was associated significantly with vascular microcalcification. Our results, although obtained by examination of a small group of patients, are in agreement with the latter, indicating no association between arterial microcalcification and AVF failure.…”