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Arterial stiffness potently predicts mortality in dialysis patients. Pulse-wave analysis permits the non-invasive assessment of indices of arterial stiffness and the central pressure waveform by applanation tonometry. The aim of this study was to assess the reproducibility of pulse-wave analysis in patients with chronic renal failure. A total of 188 subjects (23 healthy controls, along with 71 pre-dialysis, 67 dialysis and 27 transplant patients) took part. Duplicate measurements were recorded of brachial blood pressure using the semi-automated Omron 705 device and of the radial artery pressure waveform using applanation tonometry. The central pressure aortic waveform was then obtained by application of a transfer function incorporated into the SphygmoCor software. Central aortic mean blood pressure (MBP), indices of arterial stiffness [augmentation index (AIx) and time to reflection (TR)] and the subendocardial viability ratio (SEVR) were analysed for intra-observer, inter-observer and long-term reproducibility using Bland-Altman plots. The mean (+/-S.D.) intra-observer difference was 0+/-4% for AIx, 0+/-20 ms for TR, 0+/-3 mmHg for aortic MBP and 0+/-18% for the SEVR. Inter-observer mean differences were 0+/-3% for AIx, 1+/-7 ms for TR, 1+/-4 mmHg for aortic MBP and 1+/-9% for the SEVR. For the long-term study, the mean differences were -1+/-9% for AIx, -2+/-13 mmHg for aortic MBP, -2+/-12 ms for TR and 1+/-29% for the SEVR. Pulse-wave analysis showed excellent reproducibility in all the studies, and is therefore suitable for use in all patients with chronic renal failure. Further prospective and interventional studies are now required to assess whether AIx and TR are important prognostic indices of cardiovascular events, and therefore relevant surrogate indices of arterial stiffness in this susceptible population.

The impact of disordered mineral and bone metabolism following kidney transplantation is not well defined. We studied the association of serum phosphate and calcium concentrations, and surrogate measures of arterial stiffness (augmentation index: AIx and Timing of the reflected wave: Tr), with long-term kidney transplant recipient and allograft survival. Prevalent adult renal transplant patients (n = 270) were prospectively studied over a median 88-month follow-up. Detailed demographic, clinical and laboratory data, in addition to both peripheral and central non-invasive blood pressure measurements, were recorded. Higher serum phosphate and calcium levels were associated with increased all-cause mortality (HR: 1.21; 95% CI 1.09,1.35, p < 0.001 and HR: 1.22; 95% CI 1.01,1.48; p < 0.04, respectively; adjusted Cox model) and death-uncensored graft loss (p < 0.001 and p = 0.03, respectively). In addition, serum calcium and phosphate were associated with death-censored graft loss on univariable analysis (p < 0.001 and p = 0.02, respectively), but did not retain significance on multivariable analysis. AIx and Tr were not associated with mortality or graft loss on multivariable analysis. This is the first report to demonstrate that both higher serum phosphate and calcium levels are associated with increased mortality in kidney transplant recipients. It highlights the need for randomized trials assessing current interventions available for improving disordered mineral-bone metabolism post transplantation.

Arterial stiffness potently predicts mortality in dialysis patients. Pulse-wave analysis permits the non-invasive assessment of indices of arterial stiffness and the central pressure waveform by applanation tonometry. The aim of this study was to assess the reproducibility of pulse-wave analysis in patients with chronic renal failure. A total of 188 subjects (23 healthy controls, along with 71 pre-dialysis, 67 dialysis and 27 transplant patients) took part. Duplicate measurements were recorded of brachial blood pressure using the semi-automated Omron 705 device and of the radial artery pressure waveform using applanation tonometry. The central pressure aortic waveform was then obtained by application of a transfer function incorporated into the SphygmoCor software. Central aortic mean blood pressure (MBP), indices of arterial stiffness [augmentation index (AIx) and time to reflection (TR)] and the subendocardial viability ratio (SEVR) were analysed for intra-observer, inter-observer and long-term reproducibility using Bland-Altman plots. The mean (pS.D.) intra-observer difference was 0p4 % for AIx, 0p20 ms for TR, 0p3 mmHg for aortic MBP and 0p18 % for the SEVR. Inter-observer mean differences were 0p3 % for AIx, 1p7 ms for TR, 1p4 mmHg for aortic MBP and 1p9 % for the SEVR. For the long-term study, the mean differences were k1p9 % for AIx, k2p13 mmHg for aortic MBP, k2p12 ms for TR and 1p29 % for the SEVR. Pulse-wave analysis showed excellent reproducibility in all the studies, and is therefore suitable for use in all patients with chronic renal failure. Further prospective and interventional studies are now required to assess whether AIx and TR are important prognostic indices of cardiovascular events, and therefore relevant surrogate indices of arterial stiffness in this susceptible population.

No abstract