2018 Volume 43 Issue 1 Pages 34-42
Purpose: We investigated the clinical significance of blood flow measurements using ultrasonography in the anastomotic distal portion of an arteriovenous fistula (AVF).
Methods and Materials: The study population comprised 38 hemodialysis patients (right shunt: 3 patients; left shunt: 35 patients) who underwent periodic vascular-access ultrasonography at our hospital between May 2014 and December 2014. Blood flow direction and volume at the anastomotic distal portion were measured. Blood flow direction was determined using the color Doppler technique, and the time-average flow rate was measured using the pulsed-wave Doppler technique. The direction from the distal to the anastomotic portion was defined as Type 1, and the direction from the anastomotic portion to the distal portion was defined as Type 2. Blood flow volume in the two types of brachial arteries and the radial and ulnar arteries was quantitatively compared. In addition, the ratio of blood flow volume in the ulnar to that in the radial arteries (ulnar/radial) was compared. Cases with severe stenosis (＜2 mm) of lumen in the vascular access and those with a low brachial arterial blood flow volume (＜500 mL/min) were excluded.
Results: Blood flow directions and volumes in the shunt anastomotic distal portion of the AVF were as follows: Type 1, 65.8% (25 cases) and 126.1±114.9 mL/min, and Type 2, 34.2% (13 cases) and 80.4±57.6 mL/min, respectively. No significant difference was observed between blood flow types, which in flow volume of the brachial artery, the radial artery, and the ulnar artery. The ulnar/radial blood flow volume ratio was significantly different between the two studied types (Type 1: 0.44±0.22; Type 2: 0.29±0.25; p＝0.02). Steal syndrome was suspected in two cases.
Discussion: The hemodynamics of AVF revealed two types, and the blood flow directions were forward and opposite. The blood flow direction appeared to be related to the ulnar/radial blood flow volume ratio. When the blood flow is in the forward direction, in theory, brachial arterial blood flow and shunt blood flow do not have similar values. In this case, it was considered appropriate to evaluate the radial arterial blood flow volume (i.e., brachial arterial blood flow volume subtracted from brachial ulnar arterial blood flow).
Conclusion: In the present study, the clinical significance of the hemodynamics of the anastomotic distal portion of AVF using vascular-access ultrasonography was not clear. However, we clarified that the blood flow direction in the anastomotic distal portion was related to the ulnar/radial blood flow volume ratio. In addition, we proposed that shunt blood flow estimated from brachial arterial blood flow should be corrected when the blood flow direction of distal anastomosis detected forward blood flow.
