Noninvasive vascular ultrasound: an asset in vascular medicine.
TL;DR: An ultrasound system to assess diameter, blood flow velocity and volume flow in the brachial artery in man and the results showed that the diameter as assessed with the system compared favorably with the diameter of the tubing in an in vitro set-up.
Abstract: ### 1.1 Introduction
There are always moments in life, inviting to look back on the past. Entering the next millennium is certainly such an occasion, because it happens generally only once in a life-time. Therefore, we very much liked the idea of the Editors to publish a special issue of Cardiovascular Research on the occasion of this event and to explore the impact of the articles in the journal most frequently cited over the years on further developments in the field. We gladly accepted their invitation to evaluate in this respect the article by Levenson et al. published in Cardiovascular Research in 1981 [1].
### 1.2 Content of the article
In this article the authors described an ultrasound system to assess diameter, blood flow velocity and volume flow in the brachial artery in man. The apparatus consisted of an adjustable range-gated pulsed Doppler system, emitter frequency 8 MHz, combined with a double transducer system to accurately determine the angle between ultrasound beam and vessel axis. The latter is a prerequisite for accurate determination of both the velocity in and the diameter of the artery and, hence, for proper calculation of volume flow. The length of the sample volume could be adjusted by varying the length of the reception duration. A small sample volume was used to measure velocity locally in the artery and to determine the diameter of the vessel accurately and a large one to estimate the average velocity over the cross-sectional area of the vessel. A static high-pass filter with a lower cut-off frequency of 250 Hz was used to reduce interference of high amplitude low frequency signals reflected by the arterial walls. The validity of the system was tested in an in vitro set-up and the results showed that the diameter as assessed with the system compared favorably with the diameter of the tubing in …
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TL;DR: It is found that social position was inversely associated with interleukin-6 and C-reactive protein and that participants with mild depression had impaired endothelial function.
Abstract: Social position and psychosocial factors are associated with coronary disease, but the underlying pathophysiologic mechanisms remain unclear. In a sample of 283 nonsmokers, we found that social position was inversely associated with interleukin-6 and C-reactive protein and that participants with mild depression had impaired endothelial function.
155 citations
TL;DR: The most important achievements in non-invasive assessment of dynamic artery wall properties in humans with emphasis on the clinical relevance of the observations are discussed, with special attention to changes observed in aging, and in essential and borderline hypertension.
Abstract: In the past decades, non-invasive vascular ultrasound has substantially improved our insights into artery wall dynamics under normal circumstances and in disease. Although we have learned a lot, the methods in use are subject to improvement. In this review, we discuss the most important achievements in non-invasive assessment of dynamic artery wall properties in humans with emphasis on the clinical relevance of the observations. Special attention will be paid to the changes observed in aging, and in essential and borderline hypertension, because the loss of compliance (i.e. the ability to store volume thereby reducing pressure increases during ejection) of the elastic arteries in the elderly and in these patients possibly has consequences on their management. The changes in dynamic artery wall properties in diabetes and atherosclerosis are briefly discussed as well. A new approach to the determination of baroreceptor sensitivity, using artery stretch as input, is presented. The review starts with a description of the parameters most commonly used to describe dynamic artery wall properties and of the techniques employed to assess these parameters. The problems encountered in these assessments and the possible solutions to these problems are addressed as well.
146 citations
TL;DR: A critical review draws attention to the relative paucity of data on the mechanical behavior of small test portions of arterial tissues and on the relation of plaque locations to local vessel curvature and curvature flexure in epicardial arteries.
Abstract: Plaque rupture has become identified as a critical step in the evolution of arterial plaques, especially as clinically significant events occur in critical arteries. It has become common in the past dozen years or so to consider which plaques are vulnerable, even though not yet ruptured. Thrombotic events have remained significant, but in a context where they are seen as being triggered often by plaque rupture. Weaving together considerations from structural mechanics, fluid mechanics, plaque morphology, epidemiological pathology, micromechanical measurements of arterial wall tissues, and emerging information on the complex roles of the matrix metalloproteinases, this critical review draws attention to the relative paucity of data (i) on the mechanical behavior of small test portions of arterial tissues and (ii) on the relation of plaque locations to local vessel curvature and curvature flexure. This is especially important in the epicardial arteries, where combination of biplane angiograms and intravascular ultrasound (both becoming increasingly available in digital recordings) offer opportunities for clinical investigation, allied to biomechanics, to an extent previously not possible. Improved imaging and local tissue property assessments provide related opportunities for the carotid bifurcation. The discussion includes a proposal for developing an assessment scale for plaque vulnerability. © 2002 Biomedical Engineering Society.
139 citations
TL;DR: To elicit vessel wall inhomogeneities in diameter and distension along an arterial segment, a 2-D vessel wall-tracking system based on fast B-mode has been developed and can be implemented in echo systems supporting high frame rates and real-time processing of radiofrequency data.
Abstract: To elicit vessel wall inhomogeneities in diameter and distension along an arterial segment, a 2-D vessel wall-tracking system based on fast B-mode has been developed. The frame rate of a 7.5-MHz linear-array transducer (length 36 mm) is enhanced by increasing the pulse-repetition frequency to 10 kHz, decreasing the number of echo lines per frame from 128 to 64, or increasing the interspacing between echo lines with a factor of two or four. Dedicated software has been developed to extract for each echo-line the end-diastolic diameter from the B-mode image and the 2-D distension waveform from the underlying radiofrequency (RF) information. The method is validated in tubes with various focal lesion sizes. Straight segments of presumably homogeneous common carotid arteries have also been tested. The temporal and spatial SD of diameter or distension reveals inhomogeneities in time or space (i.e., inhomogeneities in artery characteristics). The method can be implemented in echo systems supporting high frame rates and real-time processing of radiofrequency data.
113 citations
TL;DR: Shear-mediated arterial vasodilation and vasoconstriction were more pronounced in women than in men, suggesting different gender-related sensitivity in the regulation of large-artery vascular tone.
113 citations
Cites background or methods from "Noninvasive vascular ultrasound: an..."
...To remove the low frequency components generated by the movements of the vessel walls without losing the low blood flow velocities close to the wall (7), a digital second-order high-pass filter is used....
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...Because of the limited resolution due to the finite size of the sample volume (7), the mean WSR was estimated from the average peak values of the derivative of the velocity profile at the anterior and posterior walls....
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..., the distribution of instantaneous velocity along the vessel’s cross section), as well as assessment of the shear rate at discrete intervals during the cardiac cycle (7)....
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References
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TL;DR: No significant difference was found between B mode-determined intimal + medial thickness in the common carotid arteries evaluated in vitro and that determined by this method in vivo in young subjects, indicating that B mode imaging represents a useful approach for the measurement of intimal - medial thickness of human arteries in vivo.
Abstract: A study in vitro of specimens of human aortic and common carotid arteries was carried out to determine the feasibility of direct measurement (i.e., not from residual lumen) of arterial wall thickness with B mode real-time imaging. Measurements in vivo by the same technique were also obtained from common carotid arteries of 10 young normal male subjects. Aortic samples were classified as class A (relatively normal) or class B (with one or more atherosclerotic plaques). In all class A and 85% of class B arterial samples a characteristic B mode image composed of two parallel echogenic lines separated by a hypoechoic space was found. The distance between the two lines (B mode image of intimal + medial thickness) was measured and correlated with the thickness of different combinations of tunicae evaluated by gross and microscopic examination. On the basis of these findings and the results of dissection experiments on the intima and adventitia we concluded that results of B mode imaging of intimal + medial thickness did not differ significantly from the intimal + medial thickness measured on pathologic examination. With respect to the accuracy of measurements obtained by B mode imaging as compared with pathologic findings, we found an error of less than 20% for measurements in 77% of normal and pathologic aortic walls. In addition, no significant difference was found between B mode-determined intimal + medial thickness in the common carotid arteries evaluated in vitro and that determined by this method in vivo in young subjects, indicating that B mode imaging represents a useful approach for the measurement of intimal + medial thickness of human arteries in vivo.
2,475 citations
TL;DR: The steady-state production rate of cells subjected to pulsatile shear stress was more than twice that of cells exposed to steadyShear stress and 16 times greater than that of Cells in stationary culture.
Abstract: Endothelial cell functions, such as arachidonic acid metabolism, may be modulated by membrane stresses induced by blood flow. The production of prostacyclin by primary human endothelial cell cultures subjected to pulsatile and steady flow shear stress was measured. The onset of flow led to a sudden increase in prostacyclin production, which decreased to a steady rate within several minutes. The steady-state production rate of cells subjected to pulsatile shear stress was more than twice that of cells exposed to steady shear stress and 16 times greater than that of cells in stationary culture.
1,260 citations
TL;DR: The association of the high-resolution ultrasound assessment of extracranial carotid morphology with the risk of acute coronary events in 1,288 eastern Finnish men was associated with a 3.29-fold (95% confidence interval, 1.31-8.29) risk of severe myocardial infarction compared with men free of any structural changes in the carOTid artery wall at baseline.
Abstract: As ultrasonographically assessed carotid arteriosclerosis is being used as a surrogate measure for coronary arteriosclerosis, we performed a prospective longitudinal study of the association of our high-resolution ultrasound assessment of extracranial carotid morphology with the risk of acute coronary events in 1,288 eastern Finnish men. The presence of any structural changes in the common carotid arteries or carotid bulbs was associated with a 3.29-fold (95% confidence interval, 1.31-8.29; p = 0.0074), intimal-medial thickening with a 2.17-fold (95% confidence interval, 0.70-6.74; p = NS), small carotid plaques with a 4.15-fold (95% confidence interval, 1.51-11.47; p less than 0.01), and large ("stenotic") plaques with a 6.71-fold (95% confidence interval, 1.33-33.91; p less than 0.01) risk of acute myocardial infarction compared with men free of any structural changes in the carotid artery wall at baseline. These data confirm the close relation between carotid artery wall morphology and coronary heart disease.
999 citations
01 Jan 1986
TL;DR: This book contains 72 chapters that discuss Nuclear Magnetic Resonance, Radionuclide Methods to Assess Cardiac Function, Perfusion Viability and Necrosis, NMR Imaging of the Cardiovascular System, Quantitative Angiographic Techniques, RNA Transcription in Heart Muscle, and Reentry Rhythms.
Abstract: This book contains 72 chapters. Some of the chapter titles are: Nuclear Magnetic Resonance; Radionuclide Methods to Assess Cardiac Function, Perfusion Viability and Necrosis; NMR Imaging of the Cardiovascular System; Quantitative Angiographic Techniques; RNA Transcription in Heart Muscle; Reentry Rhythms; and Effect of Ischemia on Cardiac Electrophysiology.
890 citations