EDITORIALS
Cardiorespiratory interaction in vasovagal syncope
International Centre for Circulatory Health, Imperial College London and Imperial College Healthcare NHS Trust, London, UK
Correspondence to:
Dr D P Francis, International Centre for Circulatory Health, 59–61 North Wharf Road, London W2 1LA, UK; rb98@doctors.org.uk
| The first 150 words of the full text of this article appear below. |
A fall in cerebral perfusion is the final common pathway leading to syncope. While we commonly investigate syncope as though the only cause of loss of perfusion is loss of arterial pressure, there is another possible contributing factor: failure of cerebral autoregulation.1
Cerebral autoregulation is the intrinsic ability of cerebral vasculature to maintain constant cerebral blood flow over a wide range of cerebral perfusion pressures.2–4 If this autoregulation is deranged, cerebral perfusion is less able to resist a decline when arterial blood pressure falls.
Clinical studies into cerebral autoregulation around the time of syncope can be carried out using provocation by head-up tilt or by lower-body negative pressure. Transcranial Doppler can be used to measure middle cerebral artery flow velocity. This can then be compared with arterial blood pressure to give an index of cerebrovascular resistance. Because both flow and pressure are fluctuating dynamically, it is useful to apply transfer
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Heart 2008 94: 1433-1439.[Abstract] [Full Text] [PDF]
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