Early inadequate venous flow volume after technically successful balloon angioplasty of radiocephalic arteriovenous fistula: causes and follow-up results.

The objective of this study was to investigate the causes of inadequate venous flow volume, which may lead to re-dysfunction in the early period after technically successful percutaneous transluminal angioplasty (PTA), and the results after one-week follow-up with or without medical treatment.This prospective case-control study included dysfunctional radiocephalic arteriovenous fistula (AVF) cases treated with PTA between December 2021-2022. After PTA, a residual stenosis of less than 30% was considered technically successful. Based on venous flow volume measured 1-2 hours after angioplasty, post-procedural doppler ultrasound (DUS) classified patients as cases (≤400 mL/min) or controls (>400 mL/min). Between groups, pre-post and control DUS parameters were compared. The correlation between fistulography lesion measurements and DUS values was investigated. The pre-procedural DUS resistive index (RI) cut-off value was determined to discriminate groups.A total of 42 patients, 21 cases and 21 controls, were included in the study. Before PTA, 67% of cases had total venous thrombosis, and 71% of controls had stenosis. Lesion measurements and residual stenosis were similar between groups (p>0.05). After PTA, 48% of cases had a free-floating thrombus in the vein, and 10% had a peri-vein hematoma. In pre-procedural DUS, flow volume was the only spectral analysis parameter paired between groups (p=0.057). In post-procedural and control DUS, controls had higher peak systolic velocity (PSV), end-diastolic velocity (EDV), and flow volume, whereas cases had a higher RI (p<0.05). Lesion length and degree of stenosis correlated positively with pre-procedural RI in both groups (p<0.05). The pre-procedural RI cut-off of 0.76 discriminated groups with 76% sensitivity, 67% specificity, 70% positive predictive value (PPV), and 74% negative predictive value (NPV).Low venous flow after PTA has been primarily associated with free-floating thrombi. Routine post-procedural DUS detects low venous flow, high RI, and small thrombi, providing evidence to initiate medical treatment that may prevent early AVF re-dysfunction.