The Influence of Dialytic Modality on Arterial Stiffness, Pulse Wave Reflections, and Vasomotor Function

Abstract

Measurements of aortic stiffness [aortic pulse wave velocity (PWV) and augmentation index (Alx)] have been established as powerful predictors of survival on hemodialysis (HD). Abnormal endothelial-dependent and endothelial-independent vascular reactivity and increased arterial stiffness are commonly described in HD patients. There is, however, a lack of information on the comparative impact of different renal replacement therapies (RRTs) on PWV and Alx, and how these different methods might influence endothelial-dependent abnormal vasodilatation. To describe in a cross-sectional design arterial compliance and distensibility in continuous ambulatory peritoneal dialysis (CAPD) versus HD versus renal transplant (RTx) patients, compared with age- and blood pressure-matched essential hypertensive controls. The PWV and aortic Alx were determined from contour analysis of arterial waveforms recorded by applanation tonometry in 40 CAPD, 41 HD, 20 RTx patients (with normal serum creatinine), and 20 controls with essential hypertension (all normotensive under treatment). Endothelial-dependent and endothelial-independent vascular reactivities were assessed by changes in Alx following challenges with inhaled salbutamol and sublingual nitroglycerin respectively. CAPD patients had significantly stiffer arteries than all other categories. The PWV was 8.29 +/- 1.09 m/ second in CAPD patients, significantly higher (p < 0.05) compared to HD subjects (7.19 +/- 1.87 m/s). Both dialysis subgroups had significantly higher PWV values compared to RTx patients (6.59 +/- 1.62 m/s) and essential hypertensive controls (6.34 +/- 1.32 m/s), p < 0.05. The Alx had a profile similar to PWV in different RRTs. All groups with the exception of CAPD subjects had a significant decrease in Alx following salbutamol. Moreover, the vasodilatation induced by either nitroglycerin or salbutamol was significantly blunted compared to HD. Overall, both dialysis categories had more abnormal responses compared to RTx patients and essential hypertensive controls. CAPD is associated with stiffer arteries and more profoundly abnormal endothelial-dependent vasomotor function, compared to matched HD subjects. These differences in arterial physical properties might explain differences seen in cardiac structure and function between the RRTs.