The Effect of Ischaemic Preconditioning on Right Ventricular Function During Exercise in Hypoxia

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Author
Bevan, Emma
Date
2015Type
Dissertation
Publisher
Cardiff Metropolitan University
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Show full item recordAbstract
Exercise in hypoxia causes severe arterial hypoxemia. The acute
cardiovascular responses include increases in heart rate (HR), cardiac output,
and sympathetic nervous system activation. In the pulmonary system, hypoxia
induces a rise in pulmonary arterial systolic pressure (PASP), but right
ventricular (RV) systolic function is maintained. The rise in PASP improves
the matching of perfusion to ventilation, but it creates a greater afterload for
the RV. For this reason it may be partly responsible for the performance
decrements reported at altitude. Whilst it is known that ischaemic
preconditioning (IPC) can attenuate the hypoxic rise in PASP, it is not known
whether it will reduce PASP during exercise in hypoxia or improve RV
function. The aim of this present study was to assess RV function during
exercise in hypoxia, and to ascertain whether IPC has the potential to reduce
PASP or improve RV function. 3 healthy males (mean ± SD; aged 23 ± 4.93
years, height 173 ± 0.35 cm and body mass 66.6 ± 10.46 Kg) visited the
laboratory on three separate occasions, and echocardiographic
measurements were taken at rest and exercise in the following conditions:
baseline normoxia, hypoxia, normoxia following IPC and hypoxia following
IPC. RV areas, PASP and tricuspid annular plane systolic excursion were
measured using echocardiography, whilst heart rate, blood pressure and
arterial oxygen saturation (SpO2) were monitored and recorded throughout.
Hypoxic exercise resulted in rises in PASP and decreases in SpO2, but it was
inconclusive whether RV systolic function was maintained. IPC did not
attenuate the hypoxic rise in PASP for all participants at rest or during
exercise; neither did it improve RV systolic function nor oxygen delivery in
hypoxia. It was concluded that the modest effect of IPC was not sufficient to
improve RV function during exercise in hypoxia.
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