Namasivayam, Mayooran (2018) Pressure, volume and flow: studies of ventricular, valvular and vascular haemodynamics in the human cardiovascular system. PhD thesis, Victor Chang Cardiac Research Institute, St Vincent's Clinical School, Faculty of Medicine, UNSW.
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Abstract
BACKGROUND: Pressure, volume and flow form the three pillars of quantification in
cardiovascular physiology. Newer approaches to their assessment provide opportunities
to further assess their interactions.
METHODS: 4 projects were conducted. Project 1 evaluated mechanisms of myocardial
oxygen supply:demand imbalance in 3682 healthy volunteers using aortic pressure-time
integrals measured with radial arterial tonometry (AT) and generalised transfer function.
Project 2 evaluated the acute left ventricular (LV) contractile response to transcatheter
mitral valve replacement (TMVR) in 9 high-risk patients. Intraoperative left and right
heart catheterisation, 3D transoesophageal echocardiography and pressure-volume
analyses were performed at baseline, immediately following TMVR and late postTMVR. Project 3 mathematically evaluated the current definition of paradoxical lowflow, low-gradient aortic stenosis (PLFLGAS) by deriving an equation for LV enddiastolic volume in terms of mean pressure gradient, aortic valve area and LV ejection
fraction. Project 4 evaluated feasibility and reproducibility of non-invasive LV
pressure-volume and aortic pressure-flow quantification in 21 patients who underwent
simultaneous AT and cardiovascular magnetic resonance imaging (CMRI).
RESULTS: In project 1, more unfavourable age-related myocardial oxygen
supply:demand profiles were seen in women than men, driven by sex differences in
arterial aging, pressure wave reflection and cardiac ejection duration. In project 2,
TMVR caused acute LV dilatation and reduction in contractility, but changes returned
to baseline by a median time of 17 minutes. LV end-diastolic pressure and forward
stroke volume were preserved at the three study timepoints. In project 3, the derived
LV end-diastolic volume equation incorporating defining criteria for PLFLGAS could
not mathematically resolve the combined input parameters based on current definitions,
raising concerns regarding the internal consistency of the consensus definition. In
project 4, non-invasive LV pressure-volume and aortic pressure-flow analyses, using
simultaneous AT and CMRI, were feasible, reproducible and showed good and
appropriately directed correlation to more conventional markers of cardiovascular
function.
CONCLUSIONS: Newer approaches to pressure, volume and flow assessment can lead
to better understanding of the interactions between the ventricles, valves and vasculature
in states of health and disease.
| Item Type: | Thesis (PhD ) |
|---|---|
| Subjects: | R Medicine > R Medicine (General) |
| Divisions: | Faculty of Medicine, Health and Life Sciences > School of Medicine |
| Depositing User: | Repository Administrator |
| Date Deposited: | 26 Oct 2020 05:10 |
| Last Modified: | 26 Oct 2020 05:28 |
| URI: | https://eprints.victorchang.edu.au/id/eprint/1024 |
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