Background/Aims: Pulse wave analysis (PWA) and pulse wave velocity (PWV) provide information about arterial stiffness and elasticity, which is mainly used for cardiovascular risk stratification. In the presented prospective observational pilot study, we examined the hypothesis that radiocephalic fistula (RCF)-related changes of haemodynamics and blood vessel morphology including high as well as low flow can be seen in specific changes of pulse wave (PW) morphology. Methods: Fifty-six patients with RCF underwent local ambilateral peripheral PWA and PWV measurement with the SphygmoCor ® device. Given that the output parameters of the SphygmoCor ® are not relevant for the study objectives, we defined new suitable parameters for PWA in direct proximity to fistulas and established an appropriate analysing algorithm. Duplex sonography served as reference method. Results: Marked changes of peripheral PW morphology when considering interarm differences of slope and areas between the fistula and non-fistula arms were observed in the Arteria radialis, A. brachialis and arterialized Vena cephalica. The sum of the slope differences was found to correlate with an increased flow, while in patients with fistula failure no changes in PW morphology were seen. Moreover, PWV was significantly reduced in the fistula arm. Conclusion: Beside duplex sonography, ambilateral peripheral PWA and PWV measurements are potential new clinical applications to characterize and monitor RCF function, especially in terms of high and low flow.

Background Pulse wave analysis may be useful to assess fistula function. We aimed to prospectively evaluate if convenient oscillometric devices are applicable to detect flow below 500 ml/min in a real life clinical setting. Methods Pulse waves were recorded ambilaterally with the vicorder® device at the brachial artery in 53 patients on haemodialysis with native fistula. Primary variables consisted of the mean slope between the systolic maximum and the diacrotic notch (Slope2), the sum of the mean slopes in the four characteristic sections of pulse waves (Slope∑) and the amplitude of relative volumetric change in the measuring cuff at the upper arm (AMP). Fistula flow was measured with the use of duplex sonography using a standardized approach. Results Parameter values above or below the median indicated measurement at the non-fistula side, with sensitivities/specificities of 0.79/0.79 (p < 0.001) for Slope 2, 0.64/0.64 (p = 0.003) for Slope∑ and 0.81/0.81 (p < 0.001) for AMP if measurements at the fistula and non-fistula arm were considered. ROC-analyses of parameter values measured at the fistula to detect low flow demonstrated AUCs (with CI) of 0.652 (0.437–0.866, p = 0.167) for Slope2, 0.732 (0.566–0.899, p = 0.006) for Slope∑ and 0.775 (0.56–0.991, p = 0.012) for AMP. The point with maximal youden’s index was regarded as optimal cut-off, which corresponded to sensitivities and specificities of 0.8/0.56 for slope2, 0.86/ 0.56 for Slope∑ and 0.93/0.78 for AMP. Conclusion Functional surveillance with oscillometry is a promising clinical application to detect a low fistula flow. Among all investigated pulse wave parameters AMP revealed the highest diagnostic accuracy. Graphical Abstract

Background and Aims Fistula-creation as well as reactive hyperaemia increase local arterial blood flow. We wanted to analyse the impact of these haemodynamic changes on pulse wave (PW) morphology to assess fistula- and endothelial function. Method We conducted a clinical pilot study including 56 patients with functioning forearm fistula. PW morphology in the A. brachialis was assessed tonometrically at the non-fistula and fistula arm using the SpygmoCor® device. We also performed a PW analysis on the non-fistula arm under the condition of reactive hyperaemia (possible in 43 patients). Duplex-sonography was used as a complementary and reference method. Results In comparison to measurements under physiologic conditions, both the fistula arm (a) and the non-fistula arm with reactive hyperemia (b) showed marked differences in the pulse wave morphology (figure). The changes in PW morphology were most prominent in the area of the diacrotic notch and could be assessed as the differences of the sum of the mean slope (Δλ in mmHg/ms) between the diacrotic notch and the main preceding and subsequent inflexion point. Measurement with duplex-sonography confirmed increased peak blood flow velocity in the arteria brachialis (ΔVmax in cm/s) under both conditions. Statistical significance could be proved for Δλ and for ΔVmax (table). Finally, bivariate regression analysis revealed a correlation of Δλ with ΔVmax (figure; c: p=0.001 and r=-0,483 for interarm-differences of the fistula and non-fistula arm; d: p= 0.030 and r=-0.343 for the differences between the physiologic state and reactive hyperaemia at the non-fistula arm). Conclusion PW analysis under high flow conditions has the potential to be a new useful clinical tool in nephrology to monitor fistula- as well as endothelial function assessed by reactive hyperaemia. The findings should be verified in a trial with clinical endpoints.

Background and Aims Pulse wave morphology changes under the high flow condition of reactive hyperaemia. We hypothesized, that those alterations may be able to indicate endothelial dysfunction. Method We recorded digitized pulse waves measured tonometrically with the SphygmoCor® device of 64 persons, 41 kidney transplant recipients and 23 healthy individuals, under normal conditions (NC) and under reactive hyperaemia (RH). Using matlab®, we calculated novel parameters, which had a temporal relationship with 3 charactereristic points (PO) of the normalized pulse wave, namely the maximum of the antegrade wave (1), the diacrotic notch (2) and the first diastolic inflection point (3). The following parameters were calculated: Mean slope between PO 1 and 2 (λ2), area under the curve (AUC) in the systole (Asys), AUC between PO 1 and 3 (A13), AUC between PO 1 and 2 (A12) and AUC between PO 2 and 3 (A23). Parameters were analyzed as their difference under reactive hyperaemia and under normal conditions. Also the maximum of the instantaneous difference of normalized pulse waves under NC und RH (Dmax) was analyzed. Endothelial function was evaluated by duplex sonography using ROC-analysis of peak systolic and end-diastolic flow difference under NC and RH. Results ROC-assessment of endothelial dysfunction as indicated by systolic peak flows demonstrated AUCs of 0.733 for λ2 (p=0.002), 0.751 for Dmax (p&lt; 0.001), 0.698 for Asys (p=0.006), 0.648 for A13 (p=0.077), 0.678 for A12 (p=0.027) and 0.732 for A23 (p=0.001). For the diastole the values were 0.753 for λ2 (p=0.003), 0.733 for Dmax (p=0.002) 0.670 for Asys (p=0.038), 0.566 for A13 (p=0.495), 0.664 for A12 (p=0.091) and 0.722 for A23 (p=0.015) respectively. Conclusion Pulse wave analysis under the condition of reactive hyperaemia probably is useful to assess endothelial function in kidney transplant recipients.