Changes in Wave Reflection With Advancing Age in Normal Subjects
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To the Editor:
From their study of a small selected group (521 of 2640 persons) within the Framingham cohort, Mitchell et al1 conclude that increase in central aortic stiffness rather than wave reflection is responsible for the increase in pulse pressure with advancing age in healthy men and women. The authors state that changes in wave reflection with advancing age are consistent with the hypothesis that a marked increase in elastic artery pulse wave velocity (PWV) with little change in muscular artery PWV leads to impedance matching between central aorta and proximal muscular arteries, which reduces proximal wave reflection and shifts reflecting sites distally. This view runs counter to classic studies that say the characteristic feature of the pressure pulse waveform with aging is attributable to early wave reflection resulting from increased elastic artery PWV and shifts of reflecting sites closer to (not further from) the heart.2
Mitchell’s calculation of reflection wave transit time (RWTT) was based on identification of an inflection point (or foot of the reflected wave) on the rising limb of the carotid pressure wave. RWTT duration (129 SD28 ms) was consistently lower than time to the end of systole (312 to 320 …