Aortic Aging in ESRD: Structural, Hemodynamic, and Mortality Implications

Abstract

Aging incurs aortic stiffening and dilation, but these changes are less pronounced in peripheral arteries, resulting in stiffness and geometry gradients influencing progression of the forward and reflected pressure waves. Because premature arterial aging is observed in ESRD, we determined the respective roles of stiffness and aortic geometry gradients in 73 controls and 156 patients on hemodialysis. We measured aortic pulse wave velocity (PWV) and brachial PWV to evaluate the stiffness gradient [(brachial PWV/aortic PWV) 0.5 ] and ascending aortic and aortic bifurcation diameters to assess aortic taper (ascending aortic diameter/aortic bifurcation diameter). The global reflection coefficient was estimated from characteristic impedance and vascular resistance. Cox proportional hazard models were used to determine mortality risk. The age-associated increase in aortic PWV was higher in patients (P,0.001). In controls, aortic ascending and bifurcation diameters increased with age, with an unchanged aortic taper. In patients on hemodialysis, age did not associate with increased ascending aortic diameter but did associate with increased aortic bifurcation diameter and decreased aortic taper, both of which also associated with abdominal aortic calcifications and smaller global reflection coefficient (P,0.001). In patients, multivariate models revealed all-cause and cardiovascular mortality associated with age, aortic PWV, and aortic bifurcation diameter with high specificity and sensitivity. Using stiffness gradient, aortic taper, or global reflection coefficient in the model produced similar results. Thus, whereas aortic stiffness is a known independent predictor of mortality, these results indicate the importance of also evaluating the aortic geometry in patients on hemodialysis. 27: 183727: -184627: , 201627: . doi: 10.1681 Aging is associated with marked changes in the mechanical and geometric characteristics of the arterial tree. 1 It is characterized by markedly increased aortic stiffness (aortic pulse wave velocity [PWV]), stiffening not observed to the same degree in peripheral muscular arteries. 2 This change reduces the normal centrifugal impedance gradient between central and peripheral artery systems. 2,3 Any change of the impedance gradient generates modifications of partial local wave reflections, which can be considered a continuous phenomenon along the impedance gradient. 3,4 The partial reflections summate to form an apparently unique backward-traveling reflected wave. 5 In the presence of impedance gradient and low aortic PWV, the backward wave returns to the aorta at end systole and early diastole, thereby enhancing late diastolic pressure and coronary perfusion 4 and attenuating the transmission of pulsatile pressure to the microcirculation. 3,6 The central effect of aortic stiffness on impedance J Am Soc Nephrol

Arterial Stiffness in Chronic Kidney Disease and End-Stage Renal Disease

“…Cardiovascular disease is a major cause of morbidity and mortality in patients with chronic kidney disease (CKD) or end-stage renal disease (ESRD) [13-15]. Premature aging and early vascular aging is the most characteristic arterial change observed in ESRD [14, 15] (Fig.…”

“…Premature aging and early vascular aging is the most characteristic arterial change observed in ESRD [14, 15] (Fig. 1).…”

“…The most characteristic arterial change observed is the arterial stiffening, more pronounced in the aorta than in peripheral arteries [6, 19]. This condition is responsible for the reduction of the arterial stiffness gradient and impedance mismatch with diminished capacity to lower pulsatile pressure transmission to the peripheral microcirculation [8, 15]. In ESRD, the aortic PWV was shown to have an independent predictive power for all-cause and CV mortality [1-3, 20, 21].…”

Targeting Blood Vessel Stiffness to Protect Kidney Function

“…A recent paper by London et al (25) has added to the field by suggesting that, in addition to assessing aortic stiffness in patients with renal disease, aortic geometry may also provide valuable prognostic information. In patients with ESRD established on hemodialysis, London et al (25) found that, such as for PWV, aortic bifurcation diameter (and aortic taper-defined as ascending aorta-to-aorta bifurcation diameters ratio) independently predicted all-cause and cardiovascular mortality.…”

“…In patients with ESRD established on hemodialysis, London et al (25) found that, such as for PWV, aortic bifurcation diameter (and aortic taper-defined as ascending aorta-to-aorta bifurcation diameters ratio) independently predicted all-cause and cardiovascular mortality. Because those with earlier stages of CKD are more likely to die from CVD than reach ESRD, they should certainly be the focus of future studies.…”