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Figure 1 Components of Arterial Load and Loading Sequence
(A) Net/total afterload is effective arterial elastance (Ea), the ratio of left ventricular (LV) end-systolic pressure (ESP) to stroke volume (SV). The red dotted lines shows an increase in Ea. (B) Characteristic impedance (Zc) is the mean of impedance moduli at harmonics 2 to 12 Hz. The Zc is elevated with aging and hypertension. (C) Late-systolic load is determined by the ratio of the augmented pressure (AP) to pulse pressure (PP): the augmentation index (AI). (D) The last one-third of the area under the pulse pressure-time integral curve (PTI3) is another measure of late-systolic load.
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