Objective: Arterial stiffening has harmful effects; peripheral pulse wave reflections deleteriously increase central pressure, but on the contrary they could also possibly be protective, as the pulse is transmitted to the microcirculation to a lesser extent. The aim of this study was, therefore, to explore the relationship between wave reflection and small vessel damage in the kidney.
Methods: In 216 hypertensive patients, data on renal resistive index, obtained by Doppler ultrasound sampling of the interlobar arteries, as well as augmentation index (AIx) and carotid-to-femoral pulse wave velocity (PWV), were retrospectively analyzed. Reflection magnitude was computed through a triangular flow estimate.
Results: AIx and reflection magnitude were positively correlated with resistive index; age, BMI, central pulse pressure, and cholesterol, but not AIx or reflection magnitude, were predictors of resistive index in multivariate analyses. Crossing tertiles of PWV and AIx, resistive index did not differ between patients with high AIx and low PWV (n = 25; 0.632 (0.064)) and those with low AIx and high PWV (n = 17; 0.645 (0.053)), despite a difference in reflection magnitude (74.9 (6.7) vs. 51.2 (7.3)%; P < 0.001).
Conclusion: Pressure wave reflection is positively correlated with resistive index in a hypertensive population. No negative relationship was found even adjusting for confounders or when it was examined separately from the influence of arterial stiffness. These findings do not support the hypothesis of peripheral wave reflections having a significant protective role for the microcirculation of a low resistance vascular bed such as the kidney.
aInstitute of Clinical Physiology, National Research Council
bDepartment of Internal Medicine, University of Pisa, Pisa, Italy
Correspondence to Francesco Stea, MD, Institute of Clinical Physiology, National Research Council, Via Moruzzi 1, 56124 Pisa, Italy. Tel: +39 050 315 8125; fax: +39 050 215 2355; e-mail: firstname.lastname@example.org
Abbreviations: AIx, augmentation index; BP, blood pressure; cDBP, central diastolic blood pressure; cPP, central pulse pressure; cSBP, central systolic blood pressure; eGFR, estimated glomerular filtration rate; HDL, high-density lipoprotein; LDL, low-density lipoprotein; PWV, pulse wave velocity; RAR, renal-aorta ratio; UACR, urinary albumin-to-creatinine ratio
Received 13 December, 2012
Revised 19 June, 2013
Accepted 17 July, 2013
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