Long-term patency of nitinol stent placement in dysfunctional hemodialysis

Abstract

Purpose: To evaluate the long-term patency of stents placement on dysfunctional hemodialysis shunt after failed balloon angioplasty and analysis the factors affecting the patency of nitinol stent.

Materials and methods: Eighty-three patients with dysfunctional dialysis shunts underwent bail-out stenting to restore vascular access. The indications included 1) residual stenosis more than 50% after percutaneous transluminal antioplasty (PTA) 2) venous rupture or dissection 3) early restenosis less than 3months after PTA. Overall cumulative primary rates at 3 months, 6months, 1-, 2-, 3-, and 4-year and secondary patency rates at 3 months, 6months, 1-, 2-, 3-, 4-, 5-, and 6-year were calculated by Kaplan-Meier survival analysis. The primary and secondary patency rates according to age and gender of the patient, history of diabetes mellitus and hypertension, diameter and length of the stent, location of the stent (central, upper arm, cubital, forearm), type of the hemodialysis shunt (native arteriovenous fistula [AVF] or arteriovenous graft [AVG]), and presence of stent fracture, were compared by Kaplan-Meier log-rank test.

Results: The stents were placed in 26 central veins (31.3%), 40 upper arm veins (48.2%), 11 cubital veins (13.3%), and 6 forearm veins (7.2%) with 100% technical and clinical success rates. The 3months, 6months, 1-, 2-, 3-, and 4-year primary patency rates were 81%, 66.7%, 43.1%, 28.8%, 25.2%, and 25.2%, respectively. The 3months, 6months, 1-, 2-, 3-, 4-, 5-, and 6-year secondary patency rates were 91.6%, 88%, 82.9%, 73.9%, 62.6%, 59.1%, 59.1%, and 29.6%, respectively. During follow up, 12 stent fractures (14.5%) were occurred in 11 peripheral veins (4 cubital veins, 7 forearm veins) and 1 central vein. There was a one case of stent migration, which located in central vein. The primary patency rates did not statistically differ according to age and gender of the patient, history of diabetes mellitus and hypertension, diameter and length of the stent, location of the stent, and type of the hemodialysis shunt. However, stent fracture group showed significantly decreased primary patency rate in comparison with non-fracture group (p=0.0004), but there was no statistical difference in secondary patency rates between two groups (p=0.58). The secondary patency rates did not statistically differ according to gender of the patient, history of diabetes mellitus and hypertension, diameter and length of the stent, location of the stent, type of the hemodialysis shunt, and stent fracture. Only older age group (≥ 65 years) showed significantly decreased secondary patency rate in comparison with younger age group (p=0.045).

Conclusion : In conclusion, nitinol stent placement is effective method to prolong dialysis access not only the central veins but also the peripheral veins including cubital veins. Stent fracture may shorten the primary patency, but not secondary patency.