Venturi effect simulating stenosis in hemodialysis arteriovenous fistulas

A collapse phenomenon associated with stenoses was observed during Doppler ultrasound (DUS) examinations in arteriovenous fistulas (AVFs).

To investigate the influence of the phenomenon over the diagnosis of stenosis, its prevalence and cause.

Comparison of luminal diameters before and during downstream compression of the efferent vein (DCEV); retrospective cross-sectional analysis of the prevalence; and theoretical analysis based on cardiovascular physiology and flow mechanicals and analysis of pressure gradients.

DCEV increased the luminal diameter at the phenomenon sites from 1.64 ± 0.78 mm to 4.03 ± 1.42 mm (p < 0.0001). The prevalence of the phenomenon was 11.3% (25) between 221 different AVFs and 16.6% (25) between 150 AFVs with stenoses. Pressure gradients in systole (147.9 ± 67.15 mmHg) and diastole (66.74 ± 37.7 mmHg) indicated intraluminal low pressures at the phenomenon sites.

The collapse phenomenon can simulate AVF stenoses ⩾50% in DUS examinations, have an important and high prevalence between AVFs with stenoses and is compatible with the Venturi effect.