Quantitative spectral analysis of carotid Doppler signal: evaluation as a method for measurement of drug effects.
Hemodynamic theories of atherogenesis suggest that the endothelial injury that initiates the process, as well as complications such as dissection and embolism, may be caused by arterial flow disturbances. Although treatment of high blood pressure prevents arteriolar complications such as brain haemorrhage and nephrosclerosis, little progress has been made in prevention of atherosclerotic events such as myocardial infarction. It is therefore desirable to develop methods for measuring the effects of antihypertensive drugs on the occurrence of such flow disturbances. We have evaluated quantitative spectral analysis of carotid Doppler signals in normals and in patients with carotid stenosis, in crossover studies of metoprolol vs placebo. Twenty healthy volunteers and 20 patients with carotid stenosis were treated in two double-blind placebo-controlled complete crossover studies, in which each subject took metoprolol 100 mg per os, and matching placebo, 1 hr before carotid scanning. In normals, peak frequency, mean frequency, and window index (WI) were measured at each of 2 sites in the left common, external and internal carotid arteries. Spectral broadening index (SBI), the ratio (peak-mean)/mean, was computed for comparison with window index (WI), the ratio of the area under the first 100 msec of the 25th percentile velocity curve to the area under the 75th percentile curve. Peak frequency, SBI and WI measure the extent of disturbance of arterial flow patterns, i.e. the extent to which flow has become non-laminar. Heart rate was reduced significantly by metoprolol, and in the external carotid artery, metoprolol significantly reduced both peak and mean frequency. Window index was not significantly changed.(ABSTRACT TRUNCATED AT 250 WORDS)
Spence
J D
JD
Department of Medicine, University of Western Ontario, London.
D000328:Adult; D001161:Arteriosclerosis / Q000503:physiopathology*; D002339:Carotid Arteries / Q000187:drug effects / Q000502:physiology* / Q000503:physiopathology; D002340:Carotid Artery Diseases / Q000503:physiopathology*; D004311:Double-Blind Method; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008790:Metoprolol / Q000494:pharmacology*; D012016:Reference Values; D014463:Ultrasonography
D008790:Metoprolol