Effects of cardiovascular medications on primary patency of hemodialysis arteriovenous fistula

Efficacy and safety of low dose, weight-based subcutaneous enoxaparin protocol in recurrent arteriovenous access thrombosis

BACKGROUND

This study aims to evaluate the safety and efficacy of a short-term, low dose, weight-based subcutaneous enoxaparin protocol (SEP) in maintaining the patency of arteriovenous (AV) access with recurrent thrombosis.

METHODS

Prospective follow-up of 25 patients who presented to a tertiary institution with recurrent AV access thrombosis and treated with anticoagulation according to SEP following successful thrombectomy. Patency and safety outcomes of SEP were studied.

RESULTS

The participants were 66.4 ± 10.2 years old and predominantly male (60%) and of Chinese ethnicity (72%). The AV accesses had a median age of 1.4 (0.6, 5.6) years with 60% being non-autogenous arteriovenous access while 40% were autogenous arteriovenous access. Thrombolytic agents (urokinase (72%) or alteplase (28%)) were used in all procedures while adjunct thrombectomy device was used in only four procedures. The mean dose of enoxaparin was 36.0 ± 8.2 mg or 0.64 ± 0.1 mg/kg/day for a mean duration 30.0 days (Interquartile range: 27.5, 31.0). One patient developed minor bleeding episode. Kaplan-Meier analysis demonstrated that the mean thrombosis-free survival pre- versus post-SEP adoption was 27.3 (95% CI 17.9-36.7) versus 183.5 (95% CI 100.1-266.9) days (p < 0.001). After adjusting for the type of thrombolytic agent, use of adjunct thrombectomy device, cutting balloon, drug-coated balloon, and stent graft, SEP remained a significant factor associated with longer thrombosis-free patency (HR 0.166: 95% CI 0.070-0.392, p < 0.001).

DISCUSSION

SEP appears to be a feasible and safe thromboprophylaxis method to improve thrombosis-free patency for AV access with recurrent thrombosis.

Parathyroid Hormone Induces Transition of Myofibroblasts in Arteriovenous Fistula and Increases Maturation Failure

CONTEXT

Arteriovenous fistula (AVF) maturation failure remains a clinical dilemma, and its pathobiology is largely unclear. Secondary hyperparathyroidism is a complication of chronic renal failure that is associated with cardiovascular disease. While parathyroid hormone (PTH) has a prosclerotic effect on vascular smooth muscle cells (VSMCs), its role in AVF maturation failure remained unknown.

OBJECTIVE

This work aimed to investigate the association between plasma PTH and AVF maturation.

METHODS

Patients receiving AVF creation were enrolled retrospectively. A mouse model of secondary hyperparathyroidism and aortocaval AVF was used to investigate the effect of PTH on an AVF lesion. A cell model of VSMCs treated with PTH in a pressurized culture system was used to disclose the signaling pathway underlying the effect of PTH on an AVF lesion.

RESULTS

In patients receiving AVF creation, higher PTH was associated with an increased risk for maturation failure. In a mouse model, vascular wall thickness and myofibroblasts of AVF significantly increased with higher PTH. When the same mice were treated with cinacalcet, AVF lesions were attenuated by suppression of PTH. A cell model showed that PTH increased the marker of myofibroblasts, integrin β6 subunit (ITGB6), via the phosphorylated protein kinase B pathway. Finally, in the same model of mice AVF, higher PTH also increased the expression of ITGB6 in the smooth muscle layer of AVF, suggesting the transition to myofibroblast.

CONCLUSION

Overall, our results suggest that higher PTH increased the risk of AVF maturation failure through increasing the transition of VSMCs to myofibroblasts. Lowering PTH may be a strategy to enhance AVF maturation.