Acute myocardial infarction and cerebral infarction are generally known to be caused primarily by the rupture of atherosclerotic plaques. It is thus necessary for clinical treatment to predict the rupture of these plaques. Blood-flow velocity around atherosclerotic plaques increases as the arteriostenosis lesion progresses, resulting in turbulence downstream of the lesion. The resulting change in blood pressure produces shear stress, and change in this stress affects the rupture of the atherosclerotic plaques. Cerebral ischemic paroxysm and cerebral infarction have been reported to occur in a high percentage of cases in which inner vessel diameter has decreased to less than 70% of its original diameter as a result of stenosis. This explains the use of standard ultrasonic diagnostic equipment to measure blood flow in the screening of the carotid arteries. On the other hand, the noise signal radiated from an aneurysm as a result of blood flow has been measured using the bruit sensor used to diagnose cerebrovascular diseases. Many unsolved problems with regard to the relationship between noise and turbulence in blood flow remain, however. Here, small vibrations on the arterial wall were measured transcutaneously and analyzed both upstream and downstream of the atherosclerotic plaque of a human carotid artery. Characteristics of the resultant vibrations upstream of the stenosis clearly differed from those downstream of it. These results should prove useful in predicting the rupture of atherosclerotic plaques.
atherosclerosis arteriostenosis blood flow small vibration on arterial wall ultrasound