The importance of accurate measurement of aortic stiffness in patients with chronic kidney disease and end-stage renal disease

Figures

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  Fig. 1. The arterial–ventricular interaction and the effect of aortic stiffening. (a) In systole, stretch of the aortic walls stores a proportion of the stroke volume while blood flows to the capillaries; this reduces the systolic pressure necessary for cardiac output to the peripheries. Aortic recoil maintains diastolic pressure (despite ventricular relaxation); this displaces stored blood, enabling continued blood flow. The LV workload is attenuated and capillary perfusion is sustained. (b) Stiffening of the aorta diminishes this storage capacity. The LV must work harder in systole to attempt to eject the entire stroke volume to the peripheries. Poor aortic recoil in diastole reduces flow to the capillaries. Systolic pressure is increased and diastolic pressure decreases. (c) Increased afterload on the LV and poor perfusion of the coronary arteries leads to concentric hypertrophy and fibrosis, impacting LV contraction and relaxation.

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  Fig. 2. Applanation tonometry to calculate cfPWV. (a) Applanation tonometry at the carotid artery using a micromanometer. Reproduced from Wilkinson et al. [47]. (b) Calculation of cfPWV using the upstroke of the waveforms to define transit time. Δt, time difference in the arrival of the foot of the waveform; ΔD, distance.

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  Fig. 3. Assessment of aPWV and AD using two-dimensional phase contrast CMR. (a) For aPWV calculation, distance is measured using an oblique sagittal cine transecting the ascending and descending aorta. (b) Phase contrast sequences are contoured to derive (c) ascending and descending aortic flow curves, from which the temporal shift between the curves can be determined. This gives transit time (the time difference between waveform arrival at the ascending and descending aorta). AD is calculated from axial cine images, taken at the bifurcation of the pulmonary trunk, by contouring the change in (d) the aortic area and a PP measured simultaneously. AA, ascending aorta; DA, descending aorta.

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  Fig. 4. Kaplan–Meier survival curve for CV deaths in an ESRD study population separated into tertiles based on cfPWV. Reproduced from Blacher et al. [100].