Hemodialysis Reduces Augmentation Index but Not Aortic or Brachial Pulse Wave Velocity in Dialysis-Requiring Patients

Abstract

Background/Aims: Arterial stiffening characterizes the vasculature of end-stage renal disease (ESRD) patients and is a strong predictor of their cardiovascular morbidity and mortality. Previous studies evaluating the effect of hemodialysis on large artery elasticity gave contradictory results. This study aimed to investigate the impact of hemodialysis on arterial stiffness and wave reflections on chronic hemodialysis patients. Methods: A total of 51 stable ESRD patients on maintenance hemodialysis were evaluated before and after the first and second dialysis session of the week. Arterial stiffness was assessed by measuring aortic and brachial pulse wave velocity (PWV). Central arterial pressure waveform parameters were estimated by radial artery applanation tonometry. Heart rate-adjusted augmentation index [AIx(75)] was used as measure of wave reflections. Results: During both dialysis sessions systolic blood pressure (SBP) and pulse pressure (PP) at brachial artery and central aorta were reduced. AIx(75) was decreased in first and second weekly dialysis session (27.5 ± 1.2 vs. 21.0 ± 1.5, p < 0.001 and 24.7 ± 1.2 vs. 20.5 ± 1.5, p < 0.001, respectively). In contrast, aortic and brachial PWV remained unchanged during both dialysis sessions. Changes in AIx(75) during hemodialysis were associated with changes in central aortic SBP, PP and ejection duration. Conclusions: This study shows that hemodialysis does not acutely affect arterial stiffness, but reduces wave reflections from periphery. This dissociation between effects of hemodialysis on PWV and AIx(75) may reflect differential impact on large and small branches of the arterial tree.

Ambulatory Recording of Wave Reflections and Arterial Stiffness during Intra- and Interdialytic Periods in Patients Treated with Dialysis

“…The present study overcomes this limitation, showing a gradual interdialytic increase in wave reflections and a steady pattern of PWV during the whole 48-hour recording. These data are consistent with our previous observations that AIx was increased between the start and end of the 3-day and 2-day interdialytic intervals in contrast to aortic and brachial PWV, which remained constant (19,33).…”

“…Recordings in hemodialysis patients were obtained shortly before and after dialysis; these are subjected to biases related to the high variability of peridialytic BP and may not accurately reflect changes in arterial cushioning function during intra-and interdialytic periods (12,14). Previous studies evaluating changes in wave reflections and arterial stiffness during dialysis had this unavoidable limitation (17)(18)(19)(20). This may explain their largely contradictory results, with most studies showing reductions in augmentation index (AIx) during dialysis (17,20) and some also revealing a parallel decrease in pulse wave velocity (PWV) (18), whereas in others PWV remain unchanged (19) or even increased (21).…”

“…Previous studies evaluating changes in wave reflections and arterial stiffness during dialysis had this unavoidable limitation (17)(18)(19)(20). This may explain their largely contradictory results, with most studies showing reductions in augmentation index (AIx) during dialysis (17,20) and some also revealing a parallel decrease in pulse wave velocity (PWV) (18), whereas in others PWV remain unchanged (19) or even increased (21).…”

Ambulatory Pulse Wave Velocity Is a Stronger Predictor of Cardiovascular Events and All-Cause Mortality Than Office and Ambulatory Blood Pressure in Hemodialysis Patients

“…32,33 In the same context, we have shown that although hemodialysis acutely reduces central SBP and AIx, PWV remained unchanged. 34 In this study, ambulatory PWV was the only vascular parameter independently predicting mortality, a finding probably related to the fact that PWV is the most direct estimate of arterial stiffness and that this analysis included the average 48-hour values of these parameters and not their variability, which in the case of AIx(75) could also be a factor affecting cardiovascular disease.…”

Diverse effects of interdialytic intervals on central wave augmentation in haemodialysis patients

“…Previous studies on acute changes of arterial cushioning function in ESRD patients evaluated mostly the effects of a single HD procedure on arterial stiffness and/or wave reflections [14,15]. To this end, we have previously shown that during HD, pulse wave velocity (PWV) is not affected but augmentation index (AIx) and central BPs significantly decrease, possibly following reduction of peripheral wave reflections [16]. However, the effects of interdialytic interval on wave reflections were investigated only in one older study reporting changes in the AIx during a 2-day interval [17].…”