Copyright 1999 American Medical Association.
All Rights Reserved. Applicable FARS/DFARS Restrictions Apply to Government Use.1999
To the Editor: Dr Grubb and colleagues1
used positron emission tomography to demonstrate the influence of
hemodynamic changes resulting from internal carotid
arteryocclusion on the subsequent occurrence of ischemic strokes.
Presumably, the reduction of cerebral blood flow due to a reduced
perfusion pressure is one of the most important determinants of the
hemodynamic changes. A recent study using ambulatory blood pressure
monitoring has shown that variations in the diurnal rhythm of blood
pressure may also influence cerebral ischemic events. Both nondipping
(a diminished nocturnal blood pressure fall) and extreme dipping (an
exaggerated fall) appear to be risk factors for silent cerebral
infarction as assessed by brain magnetic resonance imaging in elderly
persons with hypertension, when compared with the normal dipping
pattern of nocturnal blood pressure decrease.2 Thus, in
extreme dippers who also have carotid artery occlusion, aggressive
antihypertensive treatment based on an elevated clinic daytime blood
pressure might be expected to trigger ischemic cerebrovascular episodes
during the night. Since more than half of the patients described in the
study by Grubb et al1 were hypertensive, information about
the status of their antihypertensive treatment and the time of onset of
their strokes would be helpful for deciding the best medical treatment
of patients with carotid artery occlusion.
Kario K, Pickering TG. Hemodynamic Factors and Symptomatic Carotid Artery Occlusion. JAMA. 1999;281(5):420. doi:10-1001/pubs.JAMA-ISSN-0098-7484-281-5-jbk0203
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