Obesity is associated with an increased risk of developing type 2 diabetes and women with diabetes have a higher relative-risk of cardiovascular mortality than men. Polycystic ovary syndrome (PCOS) is a common condition that is associated with obesity and confers a particularly high risk of diabetes. There is a need to identify cardiovascular dysfunction in the pre-diabetic stage because, once diabetes is evident, it is difficult to improve the prognosis. Left ventricular hypertrophy (LVH) and diastolic dysfunction are well-established consequences of obesity, but the mechanisms which underpin these findings are not well-defined. Measurements of ventricular-arterial coupling characterise the load which the ventricle must overcome to eject blood. This thesis investigated whether quantitative measures of ventricular-arterial coupling could explain the development of LVH and diastolic dysfunction in young women at risk of diabetes. Two methods of quantifying ventricular-arterial coupling were used (i) a comparison of arterial and ventricular end-systolic elastance, and (ii) the amplitude and timing of wave reflections in the carotid artery using wave intensity. Increases in elastance were associated with general and central obesity. In contrast, increased wave reflections were predominantly associated with fat around the organs and with worse metabolic health. Arterial elastance and wave reflections were independent contributors of left ventricular mass but did not independently contribute to diastolic function. Women with PCOS had similar cardiovascular risk, elastance and diastolic function to matched controls. However, they had a lower odds-ratio of LVH which appeared to be explained by lower amplitude wave reflections. There may be an aspect of PCOS which mitigates the effects of obesity and pre-diabetic states on the pulsatile loading of the left ventricle. The quantification of ventricular-arterial coupling provides new insights to the effects of obesity and pre-diabetic states on sub-clinical cardiovascular disease.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:699370 |
| Date | January 2016 |
| Creators | Rees, Emma |
| Publisher | Cardiff University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://orca.cf.ac.uk/96375/ |
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