Low-pressure environment and remodelling of the forearm vein in Brescia-Cimino haemodialysis access

Background. The aim of the study was to determine which, and to what extent, haemodynamic parameters contribute to the remodelling of the venous limb of the Brescia-Cimino haemodialysis access. Methods. The dimensions of the radial artery and the venous limb of the haemodialysis access were measured by an echo-tracking technique. In six ESRD patients undergoing primary arteriovenous fistula (AVF) formation, vessel diameter, wall thickness, blood pressure and blood flow were measured after the operation, and at I and 3 months follow-up. The contralateral forearm vessels in their native position served as baseline values for comparison. Results. The diameter of the proximal antecubital vein progressively increased over the study period without reaching significant differences (4430, 5041 and 6620 mum at weeks 1, 4 and 12 respectively), whereas the intima-media thickness remained unchanged. The venous dilatation was associated with a reduction of the mean shear stress that culminated after the operation and progressively returned to normal venous values at 3 months (24.5 vs 10.4 dyne/cm(2) P < 0.043). Thus the venous limb of the AVF undergoes eccentric hypertrophy as demonstrated by the increase in wall cross-sectional area (4.42 vs 6.32 mm 2 at week 1 vs week 12, P<0.028). At the time of the operation, the blood pressure in the AVF was 151 +/- 14/92.4 +/- 11 mmHg vs 49 +/- 19/24.5 +/- 6 mmHg (means +/- SEM) for the radial artery and the venous limb of the vascular access, respectively. One year after the operation the blood pressure in the venous limb had not changed: 42+/-14 / 25.3 +/- 7 mmHg (means +/- SEM). Under these conditions, the systolo-diastolic diameter changes observed in the radial artery and the antecubital vein were within a similar range at all time points: 56 +/- 17 vs 90 +/- 26 mum (means SEM) at week 12. Conclusions. The increased circumferential stress resulting from the flow-mediated dilatation rather than the elevation of blood pressure appears to represent the main contributing factor to the eccentric hypertrophy of the venous limb of Brescia-Cimino haemodialysis access.