VOLume Flow-guided Angioplasty of Dysfunctional Autologous Arteriovenous Fistula. The VOLA Pilot Study

This is a prospective, single-center, single-arm clinical trial introducing a new functional index of clinical success of endovascular treatment and investigating the feasibility of volume flow-guided balloon angioplasty of dysfunctional AVF assessed with intraprocedural percutaneous DUS. The study will include consecutive patients undergoing fluoroscopically-guided percutaneous balloon angioplasty due to dysfunctional AVF in the investigator's center. Exclusion criteria will be: (i) not available volume flow values at the time of AVF maturation, (ii) patients with arteriovenous synthetic grafts. Patients' demographical data, dialysis access history, and procedural details will be recorded. Intraprocedural volume flow measurements will be obtained just prior to the procedure and after each balloon dilation. Volume flow measurements will be correlated with digital subtraction angiography quantitative vessel analysis (QVA) performed by an independent investigator blinded to the volume flow analysis outcomes. Follow up DUS imaging including volume-flow assessment will be set at 24h, 6, and 12 months after the index procedure, while fistulograms with QVA analysis will be performed at 6 and 12 months. All DUS measurements will be performed using the same imaging protocol and the same operator. The study's primary endpoints will be (i) the quantification of angioplasty outcome using sequential DUS volume flow analysis following each balloon catheter dilation and (ii) to assess the correlation between volume flow and clinical success defined as high-quality dialysis for a period of at least one month. Secondary endpoints will be (i) re-intervention-free interval defined as the time interval between endovascular treatment and reintervention due to dysfunction recurrence of the treated AVF and (ii) correlation between volume flow and QVA measurements.