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Title: Effects of age & blood pressure on vascular function
Author: Hickson, Stacey
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2011
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In the first study, cine phase contrast magnetic resonance imaging (PC-MRI) was validated as a total to measure pulse wave velocity (PWV). PC-MRI was then utilised to investigate the regional differences in the age-related rise in aortic pulse wave velocity. Age-related increases in arterial stiffness were greatest in the abdominal aorta, whereas the greatest increase in aortic diameter occurred in the ascending aorta. Isolated systolic hypertension (ISH), a disease of accelerated vascular ageing, may be related to a reduced aortic diameter. The third study measured compliance, distensibility, systolic and diastolic aortic diameters in the aortic root and around the aortic arch, using MRI. ISH was associated with greater diameter and reduced compliance and distensibility in the aortic arch, but not in the aortic root. The marked increase in aortic stiffness with age, with little change in peripheral stiffness can result in a reversal of the arterial stiffness gradient. This may cause impedance matching, and reduced proximal wave reflection by shifting reflection sites distally. The final study compared wave reflection amplitude (Aix) and reflection site distance between subjects with a normal and a reversed arterial stiffness gradient. A reversed stiffness gradient was associated with increased Aix and reflection site distance. These findings reject the hypothesis that preferential stiffening of the central arteries causes attenuation in the rise of Aix with age by shifting the site of wave reflection distally. This thesis demonstrated regional age-related changes in the large arteries. Specifically, aortic stiffening occurs preferentially in the abdominal region, and the smallest change occurs in the aortic arch. Aortic arch dilatation, but not aortic root dilatation, also occurs with advancing age, and to a higher degree in individuals with isolated systolic hypertension.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available