Objectives: The study attempted to highlight the varied hemodynamic effects on the different segments of arteriovenous fistula (AVF) walls.
Methods: A group of eight stage 5 chronic renal failure patients, aged about 57.8±6.8 years, with radiocephalic anastomosis was recruited. Peak systolic velocity (PSV), end diastolic velocity (EDV), diameter at end diastolic phase, and the maximum strain at the arterial inflow (Segment a), venous anastomosis (Segment b), 1 cm downstream from the anastomosis (Segment c), midway between the anastomosis and the needle puncture site (Segment d) and needle access region (Segment e) were measured with ultrasonography. The other group composed of four similar aged patients with radiocephalic fistulas underwent the intra-access pressure measurement at the above five locations accordingly. The elastic modulus (E) in each segment could be estimated.
Results: The PSV and EDV increased after entry into the fistula and the significantly greatest values were 220±42 cm/s and 113±49 cm/s respectively at Segment c. Flow velocities decreased after leaving this area. The vessel diameter increased significantly in the Segment e. The greatest strain was the Segment d and the least was the Segment e. The E decreased gradually from Segment a to d and increased at Segment e. The arterial stiffness was still significantly greater than the AVF and the least stiffness was 0.14±0.07 MPa at Segment d.
Conclusions: Heterogeneity in fistula geometry and repetitive mechanical injuries may be responsible for the uneven flow distribution.