Aim: The study aim was to determine the sequence of changes in both wall thickness and function in 'at risk' myocardium (using M-mode and radial strain/strain-rate imaging) induced by reperfusion of an acute transmural infarction, and to relate these changes to the presence or absence of a pressure-limiting stenosis in the infarct related epicardial vessel.
Methods: Eighteen closed-chest pigs were randomized into two groups (each with nine animals). In Group I, 4 weeks prior to induction of an acute transmural infarct, a copper coated stent was implanted in the proximal circumflex artery (Cx) to create a coronary artery stenosis of between 30 and 95% lumen diameter.
In the setting of regional ischemia, the "at-risk" myocardium exhibits a flow-related reduction in systolic thickening with a concomitant development of abnormal thickening after aortic valve closure (postsystolic thickening [PST]). With the introduction of high time-resolution ultrasonic-based strain/strain-rate imaging, this short lived phenomenon can be measured accurately in the clinical setting. The mechanisms underlying this ischemia-related PST are poorly understood and both active and passive etiologies have been proposed.
View Article and Find Full Text PDFThe aim of this study was to design a new approach for the acquisition of regional radial strain from the middle portion of the interventricular septum. We designed and wrote a program in Matlab (computer-assisted method) for use on a personal computer so that the septum thickness throughout the cardiac cycle could be measured instantaneously. Computer-assisted and conventional manual methods were used on the same 2D echocardiography image frames.
View Article and Find Full Text PDFBackground: The occurrence of chronic anthracycline cardiotoxicity leading to heart failure and even death is a major concern in the treatment of childhood malignancies. Currently, most treatment protocols use reduced anthracycline doses compared with historical exposure. The long-term effect of these reduced doses on myocardial function has not been well studied.
View Article and Find Full Text PDFJ Am Soc Echocardiogr
October 2007
Objective: Right ventricular (RV) failure is the main cause of mortality in patients with pulmonary hypertension (PH). Therefore, there is an increasing interest for the assessment of RV function. This study aimed to evaluate the regional RV function in patients with PH by using ultrasonic strain rate imaging.
View Article and Find Full Text PDFThe aim of this study was to describe the acute effects of anthracyclines on left ventricular systolic and diastolic function using different echocardiographic modalities. Thirteen children scheduled to receive anthracyclines were prospectively studied. They underwent complete 2-dimensional and Doppler echocardiographic evaluations, including tissue Doppler imaging, before the first dose and<2 hours after each of the first 3 doses of anthracyclines (dose range 30 to 75 mg/m2).
View Article and Find Full Text PDFUnlabelled: Active stress (sigmaA) developed by cardiac muscle has been measured in isolated muscle preparations, under physiological loading conditions, by subtracting the passive stress (sigmaP) from the total stress (sigmaT). We previously developed a mechanical model based on M-mode ultrasound imaging to calculate these stresses in beating hearts. However, this model was based on one-dimensional imaging information and could not estimate regional differences in sigmaA.
View Article and Find Full Text PDFOne-dimensional strain imaging has been shown to be angle dependent. To address this problem, a new methodology, 2D-strain, has become available. The aim of this study was to validate this methodology in an in vivo set-up against sonomicrometry.
View Article and Find Full Text PDFIEEE Trans Ultrason Ferroelectr Freq Control
September 2006
We study in this paper the statistics of the radio frequency (RF) signal in the case of partially developed speckle. Using the K distribution framework, we give the probability density function of the associated distribution, the corresponding moments, and estimators for the parameters of the distribution. The consistency of the proposed estimators is evaluated in terms of their bias and variance through numerical simulations.
View Article and Find Full Text PDFAims: Although dobutamine stress echocardiography (DSE) is an accepted tool for the diagnosis of coronary artery disease (CAD), it requires subsequent image acquisitions of the left ventricle (LV) in order to visualize all segments. This makes the procedure relatively time-consuming and might limit its accuracy. With the introduction of matrix array transducers, the real-time simultaneous acquisition of all LV segments has become possible using multi-plane imaging.
View Article and Find Full Text PDFBackground: There has been a continued search for a more sensitive noninvasive technique for detecting sub-clinical acute rejection in heart transplant recipients. Ultrasonic deformation imaging (strain/strain rate) is sensitive in detecting sub-clinical abnormalities in regional systolic function and could potentially be sufficiently sensitive to detect changes in deformation induced by graft rejection.
Aim: To assess the use of strain (S) and strain rate (SR) imaging as a noninvasive method for monitoring and diagnosing acute rejection in heart transplant recipients.
Aim: Limited data are available about the use of Doppler myocardial imaging (DMI) in small animals. We intend to provide reference values for velocity, strain and strain rate in a large group of healthy rats and studied the reproducibility and repeatability of these parameters.
Methods And Results: A total of 33 male Wistar rats (503+/-41g) underwent baseline transthoracic echocardiography with DMI of the anterior and inferior wall in a short-axis view using a 13MHz linear probe.
We report on the ultrasound characteristics of two different intracardiac tumors in newborns. The first infant presented with multiple rhabdomyomas in the context of tuberous sclerosis. Ultrasound-based strain and strain rate analysis showed that the tumors deformed in the opposite direction from the surrounding myocardial segments.
View Article and Find Full Text PDFRight ventricular (RV) blood pool-derived isovolumic relaxation time (IVRT) correlates well with systolic pulmonary arterial pressure (PAP). However, because of complex parameter derivation, the method is rarely used. The aim of this study was to validate the measurement of myocardial velocity imaging-derived RV IVRT (IVRT') against invasively measured PAP.
View Article and Find Full Text PDFBackground: Strain and strain rate have been proposed as tools to quantify regional myocardial function. One of the major pitfalls of the current methodology is its angle dependency. To overcome this problem, we have developed a new method for the estimation of strain, independent of angle.
View Article and Find Full Text PDFWe describe a level set formulation using both shape and motion prior, for both segmentation and region tracking in high frame rate echocardiographic image sequences. The proposed approach uses the following steps: registration of the prior shape, level set segmentation constrained through the registered shape and region tracking. Registration of the prior shape is expressed as a rigid or an affine transform problem, where the transform minimizing a global region-based criterion is sought.
View Article and Find Full Text PDFAims: There are no data on the use of Myocardial Velocity Imaging (MVI) to study the left atrium (LA) wall deformation. The aims of this study were to assess the feasibility of measuring regional longitudinal strain/strain rate (epsilon/SR) profiles in the LA wall, to define the normal values and to validate these measurements.
Methods And Results: MVI data were recorded in 40 healthy young individuals using a GE Vivid7 for the lateral, anterior and inferior LA walls.
Objective: The aim of this study was to investigate the clinical applicability of strain and strain rate imaging (epsilon/SRI) in heart transplantation (Htx) patients and to establish "normal" post-Htx regional systolic deformation values.
Background: Epsilon/SR indices have been shown to be a more sensitive measure of regional systolic function than standard echo measurements. Thus, they might provide a new tool to better define both normal cardiac graft function and detect changes due to post-Htx complications.
Objectives: To examine whether the line dividing the septum into two layers is found consistently by conventional echocardiography and to evaluate functional differences in the right and left side of the septum in terms of wall thickening, strain rate, and strain imaging.
Design: In a systematic study in 30 normal subjects, M mode and Doppler myocardial imaging data from the interventricular septum (IVS) were recorded. Velocity curves, regional strain rate, and strain profiles were obtained.
Objective: To investigate whether persistent ischaemic dysfunction of the myocardium after dynamic stress can be diagnosed from changes in ultrasonic strain rate and strain.
Design: Prospective observational study, with age matched controls.
Setting: University hospital.
IEEE Trans Ultrason Ferroelectr Freq Control
November 2004
Strain and strain rate imaging have been shown to be useful techniques for the assessment of cardiac function. However, one of the major problems of these techniques is their angle dependency. In order to overcome this problem, a new method for estimating the strain (rate) tensor had previously been proposed by our lab.
View Article and Find Full Text PDFOn the basis of color Doppler myocardial motion data, 1-dimensional regional natural strain rate and strain curves can now be calculated by comparing local myocardial velocity profiles. Such deformation data sets may be an important, new, and more sensitive approach to quantifying both regional radial and long-axis function of the left or right ventricle in both acquired and congenital heart disease. The normal ranges of regional velocity, strain rate, and strain values have already been determined in both adults and children.
View Article and Find Full Text PDFStrain rate imaging (SRI) is a new ultrasound (US) approach to the quantification of regional myocardial deformation. It previously has been validated in vitro and in vivo against other imaging techniques. However, in all such studies, only peak strain values were compared, and the temporal evolution of the strain curve was not studied.
View Article and Find Full Text PDFAim: Successful primary PTCA (with TIMI 3 reflow) in patients with acute transmural infarction has been observed to result in an immediate abnormal increase in wall thickness associated with persisting abnormal post-systolic thickening. To understand the sequential changes in regional deformation during: (i) the development of acute transmural infarction, (ii) upon TIMI grade 3 infarct reperfusion and (iii) during the subsequent expression of reperfusion injury the following correlative experimental study was performed in a pure animal model in which there was no distal dispersion of thrombotic material causing either no reflow or secondary microvascular obstruction.
Methods: In 10 closed-chest pigs, a 90 min PTCA circumflex occlusion was used to induce a transmural infarction.
This study investigated ventricular function in postoperative patients with abnormal origin of the the left main coronary artery from the pulmonary trunk using ultrasound-based deformation imaging. Although radial left ventricular deformation parameters were completely normalized, longitudinal deformation remained abnormal.
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