The maternal cardiovascular system at rest and in response to functional haemodynamic testing during healthy pregnancy

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Author
Meah, Victoria L.
Date
2017Type
Thesis
Publisher
Cardiff Metropolitan University
Metadata
Show full item recordAbstract
Healthy pregnancy results in significant maternal cardiac adaptation to match the
increased circulatory demands of the developing fetoplacental unit. Specifically,
cardiac output, heart rate (HR), stroke volume (SV) and end-diastolic volume
(EDV) increase, whereas mean arterial pressure and systemic vascular resistance
decrease. Despite a large body of research, there is a lack of consensus over the
magnitude and timing of these adaptations in pregnancy. Additionally, previous
studies have reported reduced systolic function in the late stages of pregnancy,
indicating that gestation may negatively influence left ventricular pumping capacity.
Testing the ability of the maternal heart to respond to additional physiological
challenge may elucidate how cardiac function is affected by healthy pregnancy.
This thesis investigated cardiovascular adaptation and functional responses
before, during and after healthy pregnancy. Firstly, a series of meta-analyses were
completed to characterise global cardiac function across healthy gestation. These
analyses showed that resting cardiac output is elevated during pregnancy, peaking
late in the third trimester but reducing towards term. Secondly, a comprehensive
assessment of cardiac structure and function was completed in healthy nonpregnant,
pregnant and postpartum females at rest. The significantly greater
cardiac output in pregnant females was result of significantly higher HR and SV.
The greater SV was result of significantly higher EDV and systolic functional
parameters (longitudinal and circumferential left ventricular strain), the latter of
which may be linked to greater sympathetic activity. Finally, the functional
cardiovascular responses of the aforementioned groups to sustained isometric
handhold and submaximal aerobic exercise were tested. During both challenges,
systolic function of pregnant females remained significantly greater. In conclusion,
healthy pregnancy alters the function of the maternal heart through lower
afterload, greater preload and enhanced systolic function. Additionally, healthy
pregnant females in the late second trimester have adequate functional responses
to increased demand and altered haemodynamic load.
Description
PhD Thesis - School of Sport
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