Objective evaluation of regional left ventricular wall motion during dobutamine stress echocardiographic studies using segmental analysis of color kinesis images

Deep Learning Synthetic Strain: Quantitative Assessment of Regional Myocardial Wall Motion at MRI

Purpose

To assess the feasibility of a newly developed algorithm, called deep learning synthetic strain (DLSS), to infer myocardial velocity from cine steady-state free precession (SSFP) images and detect wall motion abnormalities in patients with ischemic heart disease.

Materials and Methods

In this retrospective study, DLSS was developed by using a data set of 223 cardiac MRI examinations including cine SSFP images and four-dimensional flow velocity data (November 2017 to May 2021). To establish normal ranges, segmental strain was measured in 40 individuals (mean age, 41 years ± 17 [SD]; 30 men) without cardiac disease. Then, DLSS performance in the detection of wall motion abnormalities was assessed in a separate group of patients with coronary artery disease, and these findings were compared with consensus results of four independent cardiothoracic radiologists (ground truth). Algorithm performance was evaluated by using receiver operating characteristic curve analysis.

Results

Median peak segmental radial strain in individuals with normal cardiac MRI findings was 38% (IQR: 30%-48%). Among patients with ischemic heart disease (846 segments in 53 patients; mean age, 61 years ± 12; 41 men), the Cohen κ among four cardiothoracic readers for detecting wall motion abnormalities was 0.60-0.78. DLSS achieved an area under the receiver operating characteristic curve of 0.90. Using a fixed 30% threshold for abnormal peak radial strain, the algorithm achieved a sensitivity, specificity, and accuracy of 86%, 85%, and 86%, respectively.

Conclusion

The deep learning algorithm had comparable performance with subspecialty radiologists in inferring myocardial velocity from cine SSFP images and identifying myocardial wall motion abnormalities at rest in patients with ischemic heart disease.Keywords: Neural Networks, Cardiac, MR Imaging, Ischemia/Infarction Supplemental material is available for this article. © RSNA, 2023.

The Role of Phase Image in the Detection of Myocardial Dyskinesia by Magnetic Resonance Imaging (MRI)

Background:

The assessment of cardiac wall motion abnormalities plays an important role in the evaluation of many cardiovascular diseases and the prediction of functional recovery. Most of the methods dedicated to identifying the location of wall motion abnormalities have been restricted to study hypokinesia while an accurate way to assess dyskinesia is still needed in Cardiac Magnetic Resonance Imaging (CMRI). </P><P> Objective: The aim of this study is to propose a phase image based on the analytic signal able to assess the extent of the myocardial dyskinetic segments in Cardiac Magnetic Resonance Imaging (CMRI). </P><P> Materials: 22 subjects were retrospectively enrolled in this study (age 46 ± 11): 15 presenting an aneurysm and 7 control subjects with normal wall motion. For each patient, three standard views (short axis view, 2 chamber and 4 chamber views) were acquired using 3 Tesla Siemens Avanto MRI scanner and a segmented True FISP sequence. All the cine MRI images were analyzed by two experimented observers who were blinded to the diagnostic results.

Results:

The outcomes of this study show that using the proposed phase image in MRI clinical routine can increase the accuracy of the detection of myocardial dyskinetic segments from 77.23 % to 86.38 %, the sensitivity from 67.48 % to 78.86 % as well the specificity from 80.92 % to 89.23 % compared to the standard method based on cine MRI interpretation.

Conclusion:

The phase image is a promising tool in CMRI for the assessment of dyskinetic segments and the degree of myocardial asynchronism.

Value of two-dimensional strain imaging in prediction of myocardial function recovery after percutaneous revascularization of infarct-related artery

BACKGROUND

Speckle tracking is integrated into echocardiographic systems for evaluation of left ventricular (LV) function by means of automated function imaging (AFI). This study aimed at evaluating role of AFI-based strain in predicting postpercutaneous coronary intervention (PCI) LV function recovery.

METHODS

Fifty patients with anterior wall myocardial infarction and impaired LV ejection fraction (LVEF) were prospectively enrolled. All patients showed positive viability results concerning left anterior descending (LAD) artery territory using low-dose dobutamine stress echocardiography (LDSE). All patients underwent strain imaging using AFI (before and after PCI).

RESULT

Mean age of the study population was 56.2 ± 5.4 years, 34 (68%) being males. 24 (48%) patients showed post-PCI LV function recovery after 4 months. They showed higher pre-PCI LVEF and AFI-based strain values. Logistic regression analysis presented baseline LVEF as an independent predictor of LV function recovery (Odds ratio = 0.7026, 95% CI: 0.54-0.93). A pre-PCI AFI strain value of -4.5% (sensitivity: 84% and specificity: 75%) for LAD territory and -9.5% (sensitivity and specificity of 50%) for global LV predicted LV function recovery.

CONCLUSION

Assessment of global and territorial LV strains using AFI; is of added value upon viability assessment using LDSE. Higher baseline LVEF and strain values are associated with post-PCI LV function recovery.

Speckle-tracking and tissue-Doppler stress echocardiography in arterial hypertension: a sensitive tool for detection of subclinical LV impairment

Early diagnosis of cardiac alterations in hypertensive heart disease is still challenging. Since such patients might have depressed global LV systolic strain or strain rate when EF is still normal, speckle-tracking echocardiography (STE) and tissue-Doppler imaging (TDI) combined with stress echocardiography might improve early diagnosis of cardiac alterations. In this prospective study standard 2D Doppler echocardiography, STE, and TDI were performed at rest and during bicycle exercise in 92 consecutive patients—46 hypertensive subjects with normal ejection fraction and 46 healthy controls. STE and TDI were used to measure global peak systolic LV circumferential strain (CS), longitudinal strain (LS), and longitudinal strain rate (SR). Mean arterial blood pressure was significantly higher in hypertensive patients at rest (100.8 mmHg SD 13.5 mmHg; P = 0.002) and during physical exercise testing (124.2 mmHg SD 13.4 mmHg; P = 0.003). Hypertensive patients had significantly reduced values of systolic CS (P = 0.001), LS (P = 0.014), and SR (P < 0.001) at rest as well as during physical exercise—CS (P < 0.001), LS (P < 0.001), and SR (P < 0.001). Using STE and TDI, reduced LV systolic strain and strain rate consistent with early cardiac alterations can be detected in patients with arterial hypertension. These findings were evident at rest and markedly pronounced during exercise echocardiography.

Mitral Annular Systolic Velocities Predict Left Ventricular Wall Motion Abnormality During Dobutamine Stress Echocardiography

Background

Longitudinal systolic left ventricular contraction is complementary to the radial performance and can be assessed using tissue Doppler imaging (TDI). This study was performed to evaluate the contribution of mitral annular systolic velocities using TDI after dobutamine stress echocardiography (DSE).

Methods and Results

Fifty subjects with suspected coronary artery disease and chest pain were examined, using DSE as usual, as well as TDI imaging of the mitral annulus at the septal, lateral, inferior, anterior, posterior regions and the proximal anteroseptal region from the apical views, before and immediately after DSE. In 24 subjects the study was normal, while wall motion abnormality was seen in 26, 9 of them only after DSE. Mitral annular systolic velocity at the 6 locations increased significantly after DSE both in normal subjects and in those with wall motion abnormality (WMA). After DSE mitral annular septal systolic velocity in normals, 19.2 ± 3.8 cm/sec, was higher than in those with WMA, 14.6 ± 2.5 cm/sec, P < 0.0003. Post-DSE mitral systolic velocity was senstive and accurate in predicting WMA.

Conclusions

Systolic mitral TDI velocities increase after DSE, however to a lesser extent in those with wall motion abnormality, and can differentiate them from normal subjects.

Automated assessment of myocardial viability after acute myocardial infarction by global longitudinal peak strain on low-dose dobutamine stress echocardiography

BACKGROUND

Low-dose dobutamine stress echocardiography (DSE) assesses myocardial viability at the early stage of acute myocardial infarction (AMI), but its assessment is subjective and variable. Automated function image (AFI) determines global longitudinal peak strain (GLPS) based on tissue tracking technique. The ability of GLPS obtained by AFI during dobutamine stress to assess myocardial viability after AMI was investigated.

METHODS AND RESULTS

Low-dose DSE at day 3 in 23 consecutive patients with AMI was performed using Vivid 7 (GE Healthcare). Segmental longitudinal peak strain with AFI and obtained GLPS was analyzed. Wall motion score index (WMSI) by echocardiography 1 month later was determined. In 18 patients, left ventriculography was also performed at 3.2±1.5 months later to obtain left ventricular ejection fraction (LVEF) and regional wall motion (RWM, SD/chord). GLPS was improved during dobutamine infusion at 10 µg · kg(-1) · min(-1) (-12.9 ± 3.5% to -15.2 ± 3.6%, P=0.0004). GLPS during dobutamine stress showed good correlations with follow-up WMSI (R=0.47, P=0.02), with peak CK-MB (R = 0.52, P=0.01), with RWM (R = -0.48, P=0.04), and with LVEF (R = -0.54, P=0.02), whereas GLPS at baseline showed no correlations with them. Averaged segmental peak strain at baseline and during stress were correlated with follow-up WMSI (R = 0.50 and 0.43, respectively), but not with LVEF.

CONCLUSIONS

GLPS during dobutamine stress determined by AFI is a promising, objective index to assess myocardial viability on the early stage of AMI.

Power motion imaging can improve image quality in stress conditions with tachycardia

BACKGROUND

Stress echocardiographic studies are useful, but the evaluation of wall motion is sometimes suboptimal. The recently developed technique of power motion imaging can enhance mobile tissue definition.

HYPOTHESIS

The study was undertaken to determine whether power motion imaging improves endocardial definition during tachycardia compared with conventional two-dimensional (2-D) imaging.

METHODS

Twenty pigs were studied during pacing rates of 100, 120, and 150 beats/min. We compared power motion imaging with standard 2-D imaging using systolic thickening visualization (STV) scores (3 = excellent definition of systolic thickening approximately 0 = total lack of visualization of systolic thickening) at each heart rate. We calculated the sum of the scores of 22 left ventricular segments as the overall STV score, and also calculated the sum of the scores in 10 parasternal segments and 12 apical segments separately.

RESULTS

The overall STV scores in both imaging methods were similar at 100 beats/min, but scores for power motion imaging were significantly higher than those of usual 2-D imaging at 120 and 150 beats/min. Using power motion imaging, the overall STV scores were similar as heart rate was increased; however, while using standard 2-D imaging, STV scores were significantly decreased as heart rate was increased. Findings were analyzed separately by parasternal and apical images. Especially in the parasternal images, the scores were significantly increased as heart rate was increased using power motion imaging.

CONCLUSIONS

We conclude that power motion imaging improves the detection of endocardial border in stress condition with tachycardia, and thus this modality is useful for stress echocardiography.

Objective quantification of global and regional left ventricular systolic function by endocardial tracking of contrast echocardiographic sequences

BACKGROUND

Echocardiographic assessment of LV wall motion is still most frequently done visually. This study was designed to validate a new system for semi-automatic quantification of global and regional LV systolic function from contrast-enhanced cross-sectional echocardiograms.

METHODS

Measurements of LV volumes were validated in 50 patients using magnetic resonance (MR) as reference. The regional identification of the endocardial boundary was validated frame-by-frame against the visually identified border in another 27 patients. Finally, the applicability of the system for quantifying stress-echocardiographic exams was assessed in 52 patients undergoing dobutamine interventions. Echocardiographic sequences were digitally processed using custom-built algorithms, based on local phase feature descriptors, deformable contour fitting, and prospective training.

RESULTS

Compared to MR, the tracing system showed reasonable accuracy, with relative errors for end-diastolic volume, end-systolic volume, and EF of 21+/-20%, 27+/-33%, and--4+/-18%, respectively. Regional agreement of the instantaneous contours with visually traced borders was within the limits of visual reproducibility. The system was suitable for tracking stress-echo studies from all patients except two (96%). Quantification of regional radial shortening allowed to discriminate segments showing an abnormal regional wall motion with an overall area under the ROC curve of 0.87.

CONCLUSIONS

A reliable and accurate quantification of LV systolic function can be obtained by processing contrast echocardiograms. Values of LV volumes, ejection fraction, and regional endocardial shortening adequately correlate with currently available reference methods. Readily applicable to baseline and stress studies, endocardial tracking techniques increase the reliability of echocardiography for the assessment of global and regional systolic function.

Potential clinical perspectives of Doppler myocardial imaging and strain rate imaging during stress echocardiography

Stress echocardiography has become a common non-invasive test in patients with chest pain and known or suspected coronary artery disease, but, as with exercise electrocardiography, it shows several major limitations. Analysis of gray-scale images based on subjective visual interpretation of wall motion and thickening has considerable variability even among experts. Doppler myocardial imaging and strain rate imaging echocardiography provides additional information in comparison with conventional echocardiography. These techniques provide quantification of regional wall motion at rest and during stress. Quantification of both systolic and diastolic myocardial function by either Doppler myocardial imaging or strain rate imaging mapping during dobutamine stress test has been shown to be a feasible, accurate, non-invasive tool that should be considered to be a sensitive alternative to the present echocardiographic and scintigraphic imaging techniques for stress tests. Time consuming off-line analysis of color images is required in the present state of technology. However, these non-invasive techniques are rapidly evolving and expanding. Further refinements in signal processing and quantitative analysis are likely in the near future.

Sequential Changes of Myocardial Function During Acute Myocardial Infarction, in the Early and Chronic Phase After Coronary Intervention Described by Ultrasonic Strain Rate Imaging

OBJECTIVE

The aim of this prospective clinical study was to follow up patients with acute myocardial infarction from the ischemic event, over the primary coronary intervention (PCI), up to the chronic phase after survived myocardial infarction by noninvasive strain rate (SR) imaging and to determine its role in the assessment of transmurality of infarction.

METHODS

In all, 41 patients with acute S-T elevation infarction were examined immediately before, 3 days after, and 5 months after PCI. Regional myocardial function was assessed by the use of ultrasonic SR imaging and peak systolic SR and systolic strain were extracted. In addition, late-enhancement (LE) imaging with magnetic resonance imaging was done after 5 months to assess the transmurality of residual scar distribution.

RESULTS

Magnetic resonance imaging showed that 8 patients had no LE (complete recovery = no-scar group), 16 patients had subendocardial LE (nontransmural infarction = NT group), and 17 patients had a transmural LE (transmural infarction = T group) in the region of interest. Before PCI both SR and strain were markedly reduced in the ischemic segments compared with the nonischemic remote region in all 3 groups (SR: ischemia = -0.6 +/- 0.3 s(-1); remote = -1.3 +/- 0.4 s(-1), P < .001). Three days after PCI, systolic SR only increased significantly in the regions that were not transmurally infarcted. After 5 months the measurement of systolic strain could accurately distinguish the different groups. (no-scar group = -24 +/- 5%, NT group = -13 +/- 4%, T group = -1 +/- 3%).

CONCLUSIONS

This clinical study shows that with SR imaging: (1) the ischemic segment can be precisely detected; (2) the absence of transmurality early after coronary intervention can be predicted; and (3) in the chronic phase the transmurality of scar distribution can be assessed.

Dyskinesis in Chagasic myocardium: centerline analysis of wall motion using cardiac-gated magnetic resonance images of mice

We report on the use of centerline analysis of cardiac-gated magnetic resonance images to measure wall motion abnormalities in mice infected with Trypanosoma cruzi. To our knowledge, this is the first report of segmental wall motion abnormalities in an animal model of Chagas' disease. Chagas' disease patients with severe cardiac involvement exhibit mild hypokinesis in an extensive region of the left ventricle and dyskinesis in the apical region. We observed dyskinetic segments in a similar region of the hearts of infected wild-type mice. Dyskinesis was not observed in infected mice lacking macrophage inflammatory protein-1alpha, a chemokine that may play an important role in the cardiac remodeling that is normally observed in mouse models of Chagas' disease and in human patients. This study aimed to demonstrate the utility of cardiac-gated magnetic resonance imaging and centerline analysis as a straightforward method for monitoring regional left ventricular wall motion in transgenic and/or diseased mice.

Color encoding of endocardial motion improves the interpretation of contrast-enhanced echocardiographic stress tests by less-experienced readers

BACKGROUND

We hypothesized that color encoding of endocardial motion could aid less-experienced readers in detection of wall-motion abnormalities at rest and stress in patients with poor acoustic windows.

METHODS

Color-encoded images (color kinesis) were obtained at rest and peak dobutamine stress in 4 standard views during intravenous infusion of contrast agent in 117 patients with poorly visualized endocardium. In 101 of 117 patients (86%), in whom contrast enhancement allowed endocardial tracking, images were reviewed by two expert readers without color overlays. Each reader graded regional wall motion as normal, abnormal, or uninterpretable, and their consensus grades served as a gold standard. The same images were then reviewed and graded with and without color overlays by 3 cardiology fellows. The accuracy of the interpretation was calculated against the gold standard separately for the 3 vascular territories (left anterior descending, left circumflex, and right coronary arteries) and averaged for the 3 fellows.

RESULTS

With the addition of color encoding: (1) the number of uninterpretable segments decreased by 55% at rest and 61% at peak stress; and (2) all 3 fellows reached higher levels of accuracy in all 3 vascular territories both at rest (6%-82% average) and at stress (73%-80%).

CONCLUSION

The addition of color encoding of wall motion to contrast-enhanced images obtained in patients with poor acoustic windows during stress tests improves the interpretation of regional left ventricular function by less-experienced readers.

Strain Rate Dobutamine Echocardiography for Prediction of Recovery After Revascularization in Patients With Ischemic Left Ventricular Dysfunction

BACKGROUND

The purpose of the present study was to assess the accuracy of quantitative segmental analysis by strain rate imaging (SRI) technique during dobutamine test for detecting myocardial recovery after revascularization in patients with chronic ischemic regional left ventricular (LV) dysfunction and compare results with those of 2-dimensional echocardiography (2D) and tissue Doppler imaging (TDI) as well as rest-4 hours-24 hours redistribution thallium SPECT (Tl SPECT).

METHODS AND RESULTS

Forty-one patients with chronic ischemic regional LV dysfunction (EF 29 +/- 8%) underwent dobutamine 2D/TDI/SRI and Tl SPECT before and after myocardial revascularization. The sensitivity, specificity, and accuracy for the recovery of regional LV function were 73%, 81%, and 77% for dobutamine 2D; 77%, 82%, and 80% for dobutamine TDI; 86%, 88%, and 85% for dobutamine SRI; and 94%, 76%, and 84% for Tl tomography. The area under the ROC curve (AUC), which reflects the overall performance for the prediction of recovery, was 0.79 for systolic-SR, 0.81 for Tl SPECT, 0.83 for postsystolic strain, and 0.87 for isovolumic-SR. If both systolic and postsystolic SRI indexes were combined with Tl SPECT, the AUC was improved to 0.94.

CONCLUSIONS

Dobutamine SRI is more accurate than TDI in identifying hibernating myocardium. Systo-diastolic values obtained using dobutamine SRI echocardiography and values derived from nuclear perfusion techniques may be complementary in assessing myocardial viability.

The best of 2005 in echocardiography back from EuroEcho 9--Florence, Italy

The ninth edition of the congress of the European Association of Echocardiography (EAE) (former working group of Echocardiography) held in Florence has just finished with a great success of participant attendance (2.842) and abstract submissions. Hot topics at EuroEcho 9 were: 1--live 3-dimensional echocardiography and surgical decision making; in pediatric cardiology; in resynchronization therapy 2--stress echocardiography beyond wall motion: from valve diseases to contractility to coronary flow reserve to diastolic function; 3--pulmonary cardiogenic interstitial thickening recognized by ultrasonic lung comets; 4--the "proven clinical inefficacy" of the many technologies sold as breakthrough: color kinesis, tissue characterization, strain rate, tissue Doppler, applied to stress echocardiography.

Analysis of myocardial deformation based on pixel tracking in two dimensional echocardiographic images enables quantitative assessment of regional left ventricular function

OBJECTIVE

To evaluate whether myocardial strain and strain rate calculated from two dimensional echocardiography by automatic frame-by-frame tracking of natural acoustic markers enables objective description of regional left ventricular (LV) function.

METHODS

In 64 patients parasternal two dimensional echocardiographic views at the apical, mid-ventricular and basal levels were obtained. An automatic frame-by-frame tracking system of natural acoustic echocardiographic markers was used to calculate radial strain, circumferential strain, radial strain rate and circumferential strain rate for each LV segment in a 16 segment model. Cardiac magnetic resonance imaging (cMRI) was performed to define segmental LV function as normokinetic, hypokinetic or akinetic.

RESULTS

Image quality was sufficient for adequate strain and strain-rate analysis from two dimensional echocardiographic images obtained from parasternal views in 88% of segments. Obtained radial strain data were highly reproducible and analysis was affected by only small intraobserver (mean 4.4 (SD 1.6)%) and interobserver variabilities (7.3 (2.5)%). Each of the analysed strain and strain-rate parameters was significantly different between segments defined as normokinetic, hypokinetic or akinetic by cMRI (radial strain 36.8 (10.5)%, 24.1 (7.5)% and 13.4 (4.8)%, respectively, p < 0.001). Peak systolic radial strain enabled detection of hypokinesis or akinesis with a sensitivity of 83.5% and a specificity of 83.5% (cut off value 29.1%, receiver operating characteristic (ROC) curve area 0.905, 95% CI 0.883 to 0.923). Peak systolic radial strain analysis also enabled detection of akinesis versus hypokinesis with a sensitivity of 82.7% and a specificity of 94.5% (cut off value 21.0%, ROC curve area 0.946). Peak systolic radial strain-rate analysis was less accurate than peak systolic radial strain analysis to detect cMRI-defined segmental function abnormalities. The accuracy of peak systolic circumferential strain and strain rate was similar to that of corresponding radial parameters.

CONCLUSIONS

Frame-by-frame tracking of acoustic markers in two dimensional echocardiographic images enables accurate analysis of regional systolic LV function.

Correlation between the tissue Doppler, strain rate, strain imaging during the dobutamine infusion and coronary fractional flow reserve during catheterization: a comparative study

Coronary fractional flow reserve (FFR) as an invasive, and dobutamine stress echocardiography (DSE) as a noninvasive technique were used to detect critical coronary stenosis. This study was undertaken to assess correlation between these two techniques by using tissue Doppler, strain rate (SR), and strain imaging (S).

METHODS

In 17 patients (aged 54.9+/-12.6, 4 F), a total of 22 vessels were studied. On dobutamine stress echocardiography, baseline and peak systolic (Sm), early (Em) and late (Am) diastolic myocardial velocities, SR and S were recorded from parasternal view (mid-posterior segment) for radial and apical view (mid-septum) for longitudinal deformation. Then coronary FFR was performed by using intracoronary adenosine infusion, and the value of < or = 0.75 was accepted as critical coronary stenosis.

RESULTS

FFR was found to be significant in 10 vessels (FFR critical). Baseline Sm, Em/Am, SR, S values, and peak Em/Am, SR, S values were similar between critical or noncritical FFR groups. Baseline Sm and Em, and change between baseline and peak Sm and S were significantly higher in noncritical FFR group (p < 0.01, < 0.05, < 0.001, < 0.001, respectively). In all vessels, FFR after adenosine infusion showed a poor correlation with WMSI, Em, Am, Em/Am values, and the change in SR values (r = -0.22, 0.16, -0.14, 0.21, 18, respectively) showed a good correlation with the change in S (r = 0.51; p = 0.014), and a very good correlation with the change in Sm values (r = 0.77; p < 0.001) during DSE. When FFR values at left coronary system were analyzed for longitudinal SR and S values, it had a mild correlation with SR (r = 0.47, p = 0.044) and a good correlation with S (r = 0.66, p = 0.002).

CONCLUSION

The quantification of regional myocardial deformation by using DSE rather than the motion would be more appropriate in detecting the ischemic dysfunctional segment supplied by the critical coronary stenosis. Strain measurement during the dobutamine infusion may provide an information on the FFR results of the culprit vessel.

[Stunned myocardium]

BACKGROUND

Stunned myocardium is a state of delayed recovery of regional contractility after a transient period of ischemia followed by reperfusion.

CASE REPORT

A 67-year-old patient was admitted to our hospital with acute anterior myocardial infarction, and treated using percutaneous transluminal coronary angioplasty (PTCA) within acute disease stage. Reversible myocardial dysfunction persisted after ischemia following the return of normal perfusion. Abnormal resting wall motion with augmentation of contractility at low and high doses of dobutamine characterizes the stunned myocardium and reflects the normal blood flow reserve, characteristic for these postischemic, reperfused segments. SPECT (Single Photon Emission Computerized Tomography) with Tc 99 and dipyradamole showed normalization of perfusion defects in the apical region. There months after the infarction and PTCA, contractility was almost completely recovered.

CONCLUSION

Stunned myocardium recovery lasted from few weeks to few months. Control ultrasonography as well as SPECT showed normalization of systolic function of the left ventricle in the viable segments registered at previous examinations.

Automated quantitative assessment of wall motion in patients with poor acoustic windows

BACKGROUND

No technique exists for objective evaluation of left ventricular wall motion in contrast-enhanced images. We tested a new technique for quantification of regional fractional area change using contrast-enhanced power modulation imaging with color kinesis.

METHODS

The feasibility of this technique for detecting acute ischemia was first tested in 11 pigs. Next, the accuracy for detecting resting wall-motion abnormalities was determined in 52 patients requiring contrast and compared with conventional interpretation of 2-dimensional images by inexperienced readers. Expert interpretation of 2-dimensional images served as the gold standard.

RESULTS

In pigs, coronary occlusion resulted in reversible hypokinesis and reduced regional fractional area change. In patients with poor acoustic windows, this technique's accuracy for quantitative detection of resting wall-motion abnormalities was 86% compared with 81% for conventional interpretation by inexperienced readers (P <.01).

CONCLUSIONS

Regional wall motion can be accurately assessed using color-encoded power modulation imaging for patients requiring contrast. This technique may prove a useful diagnostic aid to echocardiographers of varying levels of experience.

The effects of anabolic-androgenic steroids upon resting and peak exercise left ventricular heart wall motion kinetics in male strength and power athletes

Previous investigations reported alterations in myocardial fibres and systolic function associated with anabolic-androgenic steroid consumption by athletes. Advances in bio-medical technology have allowed further investigation in assessing the possible effects of anabolic-androgenic steroids on gross left ventricular kinetics. Twenty-three male strength and power athletes with a past and current history of anabolic-androgenic steroid consumption (x 46 days, range 28 days to 70 days), were compared to 23 controls. Testing consisted of resting and immediate post-exercise transthoracic left ventricular wall cardiokymograms. Statistical results identified no difference over time between groups or condition. Cardiokymographic waveform analysis found 32.61% of all (n =184) waveforms to be abnormal (Type II, n = 56 or Type III, n = 4). There were 14 treatment subjects (60.87%) who demonstrated an abnormal waveform as compared to 9 controls (39.13%). A significant difference (p < or = 0.01) in the overall proportions of waveform types was identified where the treatment group exhibited 41.30% abnormal waveforms, compared to 23.91% by controls. Additionally, two athletes (1 treatment, 1 control) demonstrated abnormal left ventricular wall motions (Type III) analogous to impaired left ventricular performance. The results indicated: (a) highly strength trained athletes with no history of anabolic-androgenic steroid usage exhibited an unexpected high incidence of Type II waveforms (28.26% pre/23.91% post); (b) a comparable group of strength trained athletes using anabolic-androgenic steroids exhibited a significantly higher percentage of abnormal waveforms as compared to controls (34.78% pre/37.21% post). Based on these results, high intensity strength training with and without anabolic-androgenic steroid supplementation induced alterations in the left ventricular wall motion.

Use of tissue Doppler imaging to facilitate the prediction of events in patients with abnormal left ventricular function by dobutamine echocardiography

The extent of abnormality in patients with positive dobutamine echocardiography (DE) is predictive of risk, but the wall motion score (WMS) has low concordance among observers. We sought whether quantifying the extent of abnormal wall motion using tissue Doppler (TD) could guide risk assessment in patients with abnormal DE in 576 patients with known or suspected coronary artery disease; standard DE was combined with color TD imaging at peak dose. WMS was assessed by an expert observer and studies were identified as abnormal in the presence of >/=1 segments with resting or stress-induced wall motion abnormalities. Patients with abnormal DE had peak systolic velocity measured in each segment. Tissue tracking was used to measure myocardial displacement. Follow-up for death or infarction was performed after 16 +/- 12 months. Of 251 patients with abnormal DE, 22 patients died (20 from cardiac causes) and 7 had nonfatal myocardial infarctions. The average WMS in patients with events was 1.8 +/- 0.5, compared with 1.7 +/- 0.5 in patients without events (p = NS). The average systolic velocity in patients with events was 4.9 +/- 1.7 cm/s and 6.4 +/- 6.5 cm/s in the patients without events (p <0.001). The average tissue tracking in patients with events was 4.5 +/- 1.5 mm and was significant (5.7 +/- 3.1 mm) in those without events (p <0.001). Thus, TD is an alternative to WMS for quantifying the total extent of abnormal left ventricular function at DE, and appears to be superior for predicting adverse outcomes.

Simultaneous real-time echocardiographic imaging of myocardial perfusion and regional function using color-encoded, contrast-enhanced power modulation

We hypothesized that color-encoded, contrast-enhanced, power modulation imaging could allow simultaneous quantification of myocardial perfusion and regional left ventricular function. We studied 12 anesthetized, closed-chest pigs at baseline, during acute ischemia, and during reperfusion, and 8 patients after acute myocardial infarction. Color kinesis was used to color encode endocardial motion during real-time contrast perfusion imaging with high-energy ultrasound pulses. Wall motion was assessed by calculating regional fractional area changes. Translation-free perfusion analysis was performed in automatically identified myocardial regions of interest. Steady-state intensity and postimpulse rate of contrast replenishment were calculated. In all animals, ischemia caused reversible changes in the images and the perfusion- and function-calculated indices. A significant decrease in pixel intensity (14%) and contrast replenishment rate (66%) in left anterior descending coronary artery segments, in agreement with fluorescent microspheres measurements, coincided with a decrease in fractional area change (34%). For patients, respective perfusion and function indices were 61%, 51%, and 58% lower in segments where perfusion defects, regional wall-motion abnormalities, or both were noted in gray scale images. Color-encoded, contrast-enhanced power modulation allows simultaneous real-time imaging and quantitative analysis of myocardial perfusion and regional left ventricular function.

Quantitative analysis of left ventricular regional wall motion with color kinesis during abdominal aortic cross-clamping

OBJECTIVES

The authors aimed to establish a technique for quantitative analysis of regional wall motion abnormality (RWMA) using color kinesis (CK) of transesophageal echocardiography (TEE) in surgical patients. This technique was used to determine whether RWMAs develop de novo after infrarenal aortic cross-clamping in patients undergoing vascular surgery with a preoperative dipyridamole thallium stress test (DTST).

DESIGN

An observational study.

SETTING

University hospital.

PARTICIPANTS

Thirty-eight patients undergoing infrarenal abdominal aortic aneurysm resection or aortofemoral bypass.

MEASUREMENTS AND MAIN RESULTS

CK images of the left ventricle (LV) were obtained from the midventricular transgastric short-axis view before and after infrarenal aortic cross-clamping using TEE and analyzed off-line using custom software. The predictive value of the category "reversible perfusion defect" (RD) was also estimated from DTST for predicting new RWMAs with CK. CK analysis is suitable for clinical use based on the comparison with conventional two-dimensional echocardiogram measurements and interobserver variability. CK analysis showed all 7 patients with persistent perfusion defects on DTST had RWMAs. New RWMAs occurred in 2 of 9 patients with RD and in 2 of 15 patients with normal DTST, indicating that there was no significant difference between RD and normal DTST in the incidence of new RWMAs.

CONCLUSIONS

A new method is available for clinical use, which is capable of visualizing RWMAs. These results suggest that new RWMAs introduced by aortic cross-clamping occur irrespective of the risk as assessed by preoperative DTST. CK with the new analysis method might be a useful tool to quantitatively evaluate RWMAs during surgery.

Interpretation of Left Ventricular Wall Motion During Stress Testing

This article describes the obstacles to stress echocardiographic interpretation, and reviews the techniques currently available that offer a more objective approach to stress wall motion analysis than the conventional visual methodology. These techniques include Doppler-based methods, such as myocardial Doppler velocity and strain rate imaging, as well as automated border detection techniques, such as acoustic quantification and color kinesis.

Quantitative echocardiographic assessment of regional wall motion and left ventricular asynchrony with color kinesis in cardiac surgery patients

Conventional echocardiographic interpretation of regional wall motion abnormalities is subjective and experience dependent. Delayed contraction in the ejection phase (tardokinesis) and regional systolic asynchrony, sensitive markers of myocardial ischemia, cannot be accurately assessed visually. We used color kinesis (CK), a technique that evaluates spatiotemporal patterns of endocardial motion, to objectively detect regional wall motion abnormalities in patients undergoing coronary bypass surgery, and we compared it with conventional assessment of grayscale images by less experienced reviewers; we used expert grading as the gold standard for comparisons. Quantitative CK analysis agreed more closely with expert grading than less experienced reviewers (kappa coefficients, 0.74 versus 0.52 and 0.5). Global tardokinesis, identified in 9 of 26 patients (2 with normal fractional area change), was associated with an increased index of systolic asynchrony. Regional tardokinesis was identified in 48 of 150 segments: 27 segments had a normal magnitude of wall motion, 18 were hypokinetic, and 3 were severely hypokinetic/akinetic. Mildly hypokinetic segments showed delayed systolic motion, whereas residual motion of severely hypokinetic/akinetic segments occurred in early systole, reflecting passive effects produced by adjacent myocardial contraction. Quantitative CK may be a useful supplement to visual assessment, particularly for less experienced readers. By diagnosing tardokinesis, common among cardiac surgical patients even with normal standard ejection phase indices, quantitative CK may improve the intraoperative detection of regional ischemic changes.

IMPLICATIONS

Quantitative color kinesis allows for objective and sensitive intraoperative echocardiographic assessment of abnormal spatial and temporal patterns of regional ventricular wall motion, with potentially important implications for improving myocardial ischemia detection in patients undergoing cardiac surgery.

Sensitive method of detecting myocardial ischemia during dobutamine stress echocardiography

To test the hypothesis that dobutamine-induced myocardial ischemia causes early-systolic asynchrony predominantly in the regional left ventricular wall, color kinesis (CK) images during dobutamine stress echocardiography (DSE) were recorded in 13 patients with coronary artery disease and in 10 patients without, all of whom showed normal wall motion at rest. Based on the visual interpretation of DSE and the angiographic findings, 21 segments in the short-axis images at the papillary muscle level were defined as ischemic, and 60 segments of the patients without coronary artery disease were defined as normal. The incremental fractional segmental area change (IFAC) was calculated at 33-ms intervals from the CK images. At the peak dose, IFACs during the first 33 and 33-67 ms were significantly lower in the ischemic segments than in the normal ones, and IFACs during 133-167, 200-233 and 233-267 ms were significantly higher in the ischemic segments. The ratio (peak/low dose) of the cumulative fractional area change at 100 ms gave the best sensitivity (= specificity) for differentiating the 2 groups (86%). Dobutamine-induced ischemia is characterized by an early-systolic asynchrony rather than a change in overall wall excursion and CK can provide an objective assessment of ischemia developing during DSE.

Identification of acutely ischemic myocardium using ultrasonic strain measurements. A clinical study in patients undergoing coronary angioplasty

OBJECTIVES

The goal of this study was to investigate whether the changes in myocardial deformation measured with ultrasonic strain could accurately identify acutely ischemic myocardium during coronary angioplasty.

BACKGROUND

Early identification of acute myocardial ischemia has important clinical implications. The accuracy of ultrasonic strain for the detection of acute myocardial ischemia has been validated in animal experiments but has not been investigated in the clinical setting.

METHODS

In 73 patients (64 +/- 12 years), either radial or longitudinal strain values were monitored in the "at-risk" segments before, during, and early after right, circumflex, and left anterior descending coronary angioplasty. Based on the visual wall motion assessed before the angioplasty, segments were divided into normokinetic (group I) and hypo/akinetic (group II). Strain data in the "at-risk " segments were compared with values derived from the adjacent nonischemic segments and normal values in 20 controls.

RESULTS

Coronary occlusion induced a marked reduction in the systolic strain both in the radial (from 49 +/- 6.9% to 23 +/- 4.6% in group I and from 21.9 +/- 11% to 11.3 +/- 8.4% in group II, p < 0.001) and longitudinal directions. Concomitantly, postsystolic strain increased (from 3.8 +/- 3.1% to 14.6 +/- 9.5% in group I, and from 4.4 +/- 3.7% to 11.3 +/- 7.8% in group II in radial direction, p < 0.001). Upon reperfusion, all deformation parameters returned to near preocclusion values. In comparison with control, baseline, and reperfusion data, the systolic and postsystolic strain parameters measured during total coronary occlusion identified acutely ischemic myocardium with a sensitivity of 86% to 95% and a specificity of 83% to 89%.

CONCLUSIONS

In this model of acute ischemia, ultrasonic strain indexes differentiate acutely ischemic segments from both normal and dysfunctional myocardium. This should be a promising new approach to the bedside monitoring of acute ischemic changes in regional myocardial function.

Defining the transmurality of a chronic myocardial infarction by ultrasonic strain-rate imaging: implications for identifying intramural viability: an experimental study

BACKGROUND

In a correlative functional/histopathologic study, we investigated the regional deformation characteristics of both chronic nontransmural and transmural infarctions before and after a dobutamine challenge.

METHODS AND RESULTS

After stenosing copper-coated stent implantation to produce circumflex artery endothelial proliferation, 18 pigs were followed up for 5 weeks. Posteuthanasia histology showed 10 to have a nontransmural and 8 a transmural infarction. Eight nonstented animals served as controls. Regional radial function was monitored by measuring ultrasound-derived peak systolic strain rates (SR(SYS)) and systolic strains (epsilon(SYS)) (1) before stent implantation and (2) at 5 weeks, at baseline (bs) and during an incremental dobutamine infusion. In controls, dobutamine induced a linear increase in SR(SYS) (dobutamine: bs, 4.8+/-0.4 s(-1); 20 microg x kg(-1) x min(-1), 9.9+/-0.7 s(-1); P<0.0001) and an initial increase of epsilon(SYS) at low dose (bs, 58+/-5%; at 5 microg x kg(-1) x min(-1), 78+/-6%; P<0.05) but a subsequent decrease during higher infusion rates. In the nontransmural group, bs SR(SYS) and epsilon(SYS) were significantly lower than prestent values (SR(SYS), 2.9+/-0.5 s(-1) and epsilon(SYS), 32+/-6%, P<0.05 versus prestent). During dobutamine infusion, SR(SYS) increased slightly at 5 microg x kg(-1) x min(-1) (4.7+/-0.6 s(-1), P<0.05) but fell during higher infusion rates, whereas epsilon(SYS) showed no change. For nontransmural infarctions, transmural scar extension correlated closely with epsilon(SYS) at bs (r=0.88). For transmural infarctions, SR(SYS) at bs was significantly reduced and epsilon(SYS) was almost not measurable (SR(SYS), 1.8+/-0.3 s(-1); epsilon(SYS), 3+/-4%). Both deformation parameters showed no further change during the incremental dobutamine infusion.

CONCLUSIONS

Ultrasonic deformation values could clearly differentiate chronic nontransmural from transmural myocardial infarction. The transmural extension of the scar could be defined by the regional deformation response.

Effect of dobutamine on regional diastolic left ventricular asynchrony in patients with left ventricular hypertrophy

Dobutamine improves systolic as well as diastolic function, but its effect on left ventricular (LV) asynchrony is unknown. An on-line automated segmental motion analysis (A-SMA) system was developed, based on an automatic border detection technique, to evaluate the effect of dobutamine on LV asynchrony in patients with LV hypertrophy (LVH). Low dose (5 microg x kg (-1) x min(-1)) dobutamine stress echocardiography was performed in 15 patients with LVH and in 15 healthy subjects. Short-axis LV views were obtained and divided into 4 wedge-shaped segments using A-SMA. The time - area curve and its first derivative curve in each segment were displayed. Total normalized peak filling rates (nPFR) were obtained. Systolic and diastolic asynchronies were assessed from the coefficient of variation (CV) of the regional time intervals from end diastole to the peak ejection rate (T-PER), and from end systole to the peak filling rate (T-PFR), respectively. At baseline, the CV of T-PER and T-PFR in patients with LVH were greater than those in healthy subjects (CV-T-PER: 18.8+/-9.2 vs 9.6+/-4.3%, CV-T-PFR: 19.5+/-7 vs 8.1+/-4.1%, both p<0.01). During dobutamine infusion, differences among groups at baseline disappeared and systolic and diastolic asynchronies improved (CV-T-PER: 7.3+/-4.8 vs 5.7+/-2.1%, CV-T-PFR: 6.8+/-3.5 vs 5.1+/-1.3%, both p>0.05). Total nPFR increased (from 3.2+/-1.0 /s to 5.6+/-1.3 /s, p<0.01) with dobutamine infusion in patients with LVH. Dobutamine improved LV diastolic asynchrony, as evaluated by A-SMA, in patients with LVH demonstrating that the lusitropic effect of dobutamine improved LV regional diastolic asynchrony, playing an important role in the improvement of global LV diastolic filling.

Color kinesis during contrast-enhanced dobutamine stress echocardiography: feasibility and applicability

Accurate interpretation of dobutamine stress echocardiography (DSE) needs expertise. Color kinesis (CK) allows objective assessment of wall motion (WM), and its feasibility and accuracy are enhanced under harmonic imaging with contrast agents. To explore its utility, CK was performed in 41 unselected patients during contrast-enhanced DSE. After bolus injection of Levovist, the CK image was acquired in the apical 4- and 2-chamber views at baseline and peak stress using the ultraharmonic mode. Quad screen format with second harmonic imaging after another injection of Levovist was also obtained as a reference. Regional WM (12 segments in the apical view) was independently assessed by both methods. Heart rate increased from 67 beats/min at baseline to 135 beats/min (88% of age predicted maximal heart rate) at peak stress. The CK image was successfully obtained in all patients at baseline and in 38/41 patients at peak stress. CK tracked endocardial motion accurately in 93% (456/492) of left ventricular segments at baseline and 87% (427/492) at peak stress. The concordance rate of normal and abnormal WM between the 2 methods was 86% (392/456, Kappa 0.61) at baseline and 85% (362/427, kappa 0.53) at peak stress. Among the 38 patients in whom both methods were completed, the standard quad screen display showed abnormal DSE results in 17 patients and 28/114 vascular territories. The sensitivity, specificity and diagnostic accuracy of CK for detecting abnormal findings were, respectively, 71% (12/17), 90% (19/21) and 82% (31/38) in patients and 57% (16/28), 97% (83/86) and 87% (99/114) in vascular territories. The application of CK was highly feasible during contrast-enhanced DSE and gave an objective assessment of WM. This method can be a valuable adjunct to the conventional interpretation of DSE.

Use of myocardial backscatter as a quantitative tool for dobutamine echocardiography: feasibility, response to ischemia and accuracy compared with coronary angiography

BACKGROUND

Integrated backscatter (IB) changes with ischemia, but most prior studies have involved parasternal imaging, which limited the number of evaluable segments. We sought to assess the efficacy and feasibility of IB from the apical views, and compare this to myocardial Doppler findings and wall motion analysis during dobutamine echocardiography.

METHODS AND RESULTS

Forty-one patients undergoing dobutamine echocardiography had gray scale images and color myocardial Doppler acquired in three apical views. Cyclic variation IB (CVIB), time to peak IB (tIB, corrected for QT interval) and Doppler peak velocity (PV) in the same segment at rest and peak stress were assessed offline from digital cineloops at 80-120 frames/s. Significant coronary disease was defined by quantitative angiography as > 50% stenosis. Analysis of the waveform in the apical views was feasible in 82% of segments. The backscatter curve was shown to be biphasic, with correlation of the first peak with peak tissue velocity, and significant regional variation. However, the response to normal segments was different with tissue Doppler (increased velocity) and backscatter (no change). Ischemia was associated with a lower peak tissue velocity and lower CVIB. Only resting tissue velocity and tIB (not CVIB) distinguished scar from ischemic segments. Using an optimal cutoff of < 5.3 dB at rest achieved a sensitivity of 55%, a specificity of 76% and an accuracy of 75% when compared to angiography. The same cutoff at peak achieved a sensitivity of 58%, a specificity of 80% and an accuracy of 76%.

CONCLUSIONS

CVIB and tissue velocity responses to stress are different, but both may be used to identify abnormal segments in patients with CAD. However, while measurement of CVIB is feasible in the apical views, the variability caused by anisotropy limits the accuracy of a single cutoff.

Diastolic filling abnormalities by color kinesis in newborns exposed to intrauterine cocaine

Because cocaine crosses the placenta, we prospectively evaluated global and segmental systolic and diastolic cardiac function by color kinesis in clinically asymptomatic newborns who were exposed to cocaine in utero (group 1, n = 82). Their data were compared with normal controls (group 3, n = 87) and newborns exposed to drugs other than cocaine (group 2, n = 108). During left ventricular filling, newborns exposed to cocaine, compared with groups 2 and 3, had significantly (P <.05) higher global fractional area change (%) (76 +/- 10.3 vs 72 +/- 9.4 and 72 +/- 9.1, respectively), regional fractional area changes (%) for the anterior, septal, inferior, and lateral wall, and in the index of asynchrony (at 50% filling 13.2 +/- 5.8 vs 11.3 +/- 4.1 and 11.6 +/- 4.2, respectively). There were no significant differences in systolic function among the 3 groups. Prenatal cocaine exposure in asymptomatic infants leads to higher global and segmental fractional area changes and asynchrony during diastole. The significance and course of these alterations require further investigation.

Quantification of regional left ventricular wall motion in newborns by color kinesis

BACKGROUND

Normal values for regional left ventricular wall motion, although documented in adults, have not been reported in healthy newborns.

METHODS

This study prospectively evaluated global and segmental systolic and diastolic cardiac function by color kinesis in clinically asymptomatic healthy newborns.

RESULTS

Eighty-eight asymptomatic infants who were less than 48 hours old were studied. Systolic and diastolic parameters of global and regional left ventricular function are reported as means +/- SD, medians, 5th and 95th percentiles to establish the normative values for newborns. The reported fractional area changes during systole and diastole are similar to the reported normal values for older subjects. Higher body surface area significantly correlated with an increased peak velocity during systole, and fractional area changes during filling of the lateral wall.

CONCLUSIONS

Our report of left ventricular regional wall-motion characteristics of healthy newborns, as evaluated by color kinesis, may help in the objective evaluation and management of newborns suspected to have global or segmental ventricular dysfunction.

Objective assessment of left ventricular wall motion from contrast-enhanced power modulation images

There is no method to objectively evaluate left ventricular (LV) function from contrast-enhanced images. We tested the feasibility of evaluating regional LV function by using power modulation imaging. In protocol 1, 9 anesthetized closed-chest pigs were studied. Images were obtained during contrast infusion at baseline, during LAD occlusion and reperfusion. In protocol 2, images were obtained in 20 patients (14 wall-motion abnormalities; 6 controls) during contrast enhancement. Off-line, frame-by-frame, semiautomated endocardial border detection was followed by color encoding of endocardial motion, followed by segmentation and calculation of regional fractional area changes. In all animals, coronary occlusions resulted in hypokinesis and decreased fractional area changes in LAD-related segments only, which were reversed during reperfusion. In patients, wall-motion analysis was in agreement with an expert reader of dynamic images in 92.5% segments, with interobserver variability of 12.5%. Color encoding of endocardial motion from contrast-enhanced power modulation images allows accurate quantitative assessment of regional LV function.

Transesophageal dobutamine stress echocardiography with tissue Doppler imaging for detection and assessment of coronary artery disease

BACKGROUND

Transesophageal dobutamine stress echocardiography (T-DSE) has been shown to be a sensitive and specific technique for the detection of myocardial ischemia. A major limitation of echocardiographic study interpretation, however, is the subjective visual analysis of endocardial motion and wall thickening, which is only semiquantitative.

METHODS

To analyze whether T-DSE with the use or tissue Doppler imaging (TDI) during graded dobutamine infusion may be useful to detect and quantify stress-induced myocardial ischemia by changes in myocardial velocities, 70 patients undergoing coronary arteriography were studied with T-DSE and TDI. Midesophageal and transgastric short- and long-axis images were obtained at each level of dobutamine infusion. T-DSE was successful in 67 patients (96%). Baseline resting pulsed and color peak systolic (S) and early diastolic (E) velocities of the anterior, septal, lateral, and inferior walls were examined.

RESULTS

Pulsed and color TDI correlated well at rest and after stress. Fifteen patients had a normal response to dobutamine, and 52 patients had inducible ischemia by two-dimensional criteria. In the normal group, there was a significant dose-dependent increase in S and E velocities. Compared with those in the normal group, patients with coronary artery disease (CAD) had lower resting S and E velocities and blunted S wave increase or E wave decrease during DSE.

CONCLUSIONS

T-DSE with TDI is a feasible and accurate test for the quantitative assessment of patients with CAD who have impaired augmentation of systolic and diastolic myocardial velocities during dobutamine infusion.

New method of on-line quantification of regional wall motion with automated segmental motion analysis

We have recently developed an automated segmental motion analysis (A-SMA) system, based on an automatic "blood-tissue interface" detection technique, to provide real-time and on-line objective echocardiographic segmental wall motion analysis. To assess the feasibility of A-SMA in detecting regional left ventricular (LV) wall motion abnormalities, we performed 2-dimensional echocardiography with A-SMA in 13 healthy subjects, 22 patients with prior myocardial infarction (MI), and 9 with dilated cardiomyopathy (DCM). Midpapillary parasternal short-axis and apical 2- and 4-chamber views were obtained to clearly trace the blood-tissue interface. The LV cavity was then divided into 6 wedge-shaped segments by A-SMA. The area of each segment was calculated automatically throughout a cardiac cycle, and the area changes of each segment were displayed as bar graphs or time-area curves. The systolic fractional area change (FAC), peak ejection rate (PER), and filling rate (PFR) were also calculated with the use of A-SMA. In the control group, a uniform FAC was observed in real time among 6 segments in the short-axis view (60% +/- 10% to 78% +/- 9%), or among 5 segments in either the 2-chamber (59% +/- 12% to 75% +/- 16%) or 4-chamber view (58% +/- 13% to 72% +/- 12%). The variations of FAC, PER, and PFR were obviously decreased in infarct-related regions in the MI group and were globally decreased in the DCM group. We conclude that A-SMA is an objective and time-saving method for assessing regional wall motion abnormalities in real time. This method is a reliable new tool that provides on-line quantification of regional wall motion.

A prospective comparison of echocardiographic wall motion score index and radionuclide ejection fraction in predicting outcome following acute myocardial infarction

OBJECTIVE

To characterise echocardiographic wall motion score index (WMSI) as a surrogate measure of left ventricular ejection fraction (EF) following acute myocardial infarction (AMI) and to compare its prognostic value with that of EF measured by radionuclide ventriculography (RNV).

DESIGN

A prospective study to compare baseline echocardiographic WMSI with RNV EF in consecutive patients thrombolysed for AMI, both performed on the same day before discharge, and their relative prognostic values in predicting cardiac events.

SETTING

District general hospital coronary care unit and cardiology department.

PATIENTS

120 consecutive patients free of exclusion criteria thrombolysed for AMI and followed up for a mean (SD) of 13 (10) months.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Correlation coefficients and receiver operating characteristic curve analyses plus cardiac event rates at follow up between RNV EF and echocardiographic WMSI.

RESULTS

WMSI correlated well with RNV EF. The best corresponding WMSIs for EFs 45%, 40%, and 35% were 0.6, 0.8, and 1.1, respectively. There were 42 cardiac events during follow up. Although both RNV EF and WMSI were strong univariate predictors of cardiac events, only WMSI independently predicted outcome in a multivariate model. All three WMSI cut offs significantly predicted events, while an RNV EF cut off of </= 45% v > 45% failed to reach significance.

CONCLUSIONS

Although both RNV and echocardiographic WMSI strongly predicted cardiac outcome, WMSI, a cheaper and more readily available technique, is more discriminatory, especially in cases of mild left ventricular dysfunction following AMI.

Noninvasive quantification of the contractile reserve of stunned myocardium by ultrasonic strain rate and strain

BACKGROUND

We sought to investigate ultrasonic strain rate and strain as new indices to quantify the contractile reserve of stunned myocardium during dobutamine infusion.

METHODS AND RESULTS

Stunning of the left ventricular posterior wall was induced in 9 closed-chest pigs after 30 minutes of severe hypoperfusion followed by 60 minutes of reperfusion of the left circumflex coronary artery territory. A second group of 7 animals had no coronary occlusion and served as normal controls. An incremental dobutamine infusion protocol was used in both groups. Changes in regional radial function were monitored by use of ultrasound-derived maximal systolic radial strain rate (SR) and systolic strain (epsilon). In the control group, dobutamine induced an increase in both SR and maximal dP/dt, which correlated linearly (r=0.85). Conversely, epsilon values increased at low doses of dobutamine (2.5 to 5 microg. kg(-1). min(-1)) but decreased during higher infusion rates (10 to 20 microg. kg(-1). min(-1)). During circumflex hypoperfusion, SR and epsilon of the posterior wall decreased from 5.0+/-0.3 s(-1) and 63+/-6% to 2.9+/-0.3 s(-1) and 27+/-4%, respectively (P<0.01). After 60 minutes of reperfusion, SR and epsilon failed to fully resume because of stunning, averaging 3.6+/-0.2 s(-1) and 35+/-3%, respectively (P=0.12 versus ischemia, P<0.05 versus baseline). During dobutamine infusion, SR increased at 5 microg. kg(-1). min(-1) and exceeded baseline values at 20 microg. kg(-1). min(-1) (P<0.05), whereas epsilon increased only at high doses and remained below baseline levels (P<0.05).

CONCLUSIONS

The changes in regional function of stunned myocardium during inotropic stimulation could be characterized by use of ultrasonic deformation parameters. During dobutamine infusion, strain-rate values quantified the contractile reserve better than strain values.

Effect of tissue Doppler on the accuracy of novice and expert interpreters of dobutamine echocardiography

The subjective interpretation of dobutamine echocardiography (DBE) makes the accuracy of this technique dependent on the experience of the observer, and also poses problems of concordance between observers. Myocardial tissue Doppler velocity (MDV) may offer a quantitative technique for identification of coronary artery disease, but it is unclear whether this parameter could improve the results of less expert readers and in segments with low interobserver concordance. The aim of this study was to find whether MDV improved the accuracy of wall motion scoring in novice readers, experienced echocardiographers, and experts in stress echocardiography, and to identify the optimal means of integrating these tissue Doppler data in 77 patients who underwent DBE and angiography. New or worsening abnormalities were identified as ischemia and abnormalities seen at rest as scarring. Segmental MDV was measured independently and previously derived cutoffs were applied to categorize segments as normal or abnormal. Five strategies were used to combine MDV and wall motion score, and the results of each reader using each strategy were compared with quantitative coronary angiography. The accuracy of wall motion scoring by novice (68 +/- 3%) and experienced echocardiographers (71 +/- 3%) was less than experts in stress echocardiography (88 +/- 3%, p <0.001). Various strategies for integration with MDV significantly improved the accuracy of wall motion scoring by novices from 75 +/- 2% to 77 +/- 5% (p <0.01). Among the experienced group, accuracy improved from 74 +/- 2% to 77 +/- 5% (p <0.05), but in the experts, no improvement was seen from their baseline accuracy. Integration with MDV also improved discordance related to the basal segments. Thus, use of MDV in all segments or MDV in all segments with wall motion scoring in the apex offers an improvement in sensitivity and accuracy with minimal compromise in specificity.

Recent advances in echocardiographic evaluation of left ventricular anatomy, perfusion, and function

This article provides a brief overview of several recently developed, emerging technologies and discusses their potential uses on clinical grounds. These new technologies include three-dimensional imaging, objective automated evaluation of ventricular function with acoustic quantification, assessment of regional ventricular performance using color kinesis and tissue Doppler imaging, harmonic imaging, and power Doppler imaging. Our hope is that readers will gain a better understanding of the principles underlying these technological advances, which will help them to integrate these new techniques efficiently into their clinical practices.

Detection of regional temporal abnormalities in left ventricular function during acute myocardial ischemia

Echocardiographic diagnosis of myocardial ischemia is based on visualizing hypokinesis, which occurs late in the ischemic cascade. We hypothesized that temporal changes in endocardial motion may constitute sensitive early markers of ischemia. Two protocols were performed in 19 anesthetized pigs. Protocol 1 included 54 intracoronary balloon occlusions. Transthoracic images were acquired at baseline and every 15 s during 5 min of occlusion and reperfusion. In protocol 2, ischemia was induced in 12 animals by use of graded dobutamine infusion, after creating significant partial occlusions without a resting wall motion abnormality. Systolic and diastolic endocardial motion was color encoded using color kinesis and analyzed using custom software. All ischemic episodes caused detectable and reversible changes. The earliest sign of ischemia was tardokinesis in 31/54 occlusions, whereas hypokinesis appeared first in 23/54 cases. Dobutamine-induced ischemia caused tardokinesis first in 9/12 and hypokinesis in 3/12 animals. Reversible ischemic changes in regional left ventricular performance can be objectively detected using analysis of echocardiographic images and will likely improve the early noninvasive diagnosis of acute ischemia.

Stress echocardiography in the diagnosis of coronary artery disease

Stress echocardiography (SE) is currently a widely accepted method for the diagnostic and prognostic assessment of coronary artery disease. This article reviews new concepts in SE, such as new stress techniques, new methods of endocardial border detection, strain, tissue Doppler velocities, and others. Although some of these techniques are in their infancy, we believe that they will become widely accepted.

Positron emission tomography and low-dose dobutamine echocardiography in the prediction of postrevascularization improvement in left ventricular function and exercise parameters

BACKGROUND

We studied the value of low-dose dobutamine echocardiography (LDDE) and positron emission tomography (PET) in predicting improvement of left ventricular function and exercise parameters after revascularization.

METHODS

Forty-six consecutive patients with ischemic heart disease and an ejection fraction (EF) of 35% +/- 7% were included. Before revascularization, the patients underwent exercise testing and myocardial viability testing by LDDE and fluoride 18-fluoro-2-deoxyglucose PET. Six months after revascularization they underwent coronary angiography to study graft patency, and echocardiographic examination and the exercise test were repeated.

RESULTS

In the prediction of the presence or absence of improved postrevascularization function in left ventricular regions with patent grafts, PET was more sensitive than LDDE (42/52 regions [81%] vs 27/52 regions [51%], P <.01), whereas LDDE was more specific than PET (187/209 regions [89%] vs 118/209 regions [56%], P <.001). Improvement of regional myocardial dysfunction was found in 19 patients, but their global left ventricular function did not improve significantly (EF 34% +/- 6% and 36% +/- 7%). In the remaining 27 patients with irreversible dysfunction, EF decreased (EF 36% +/- 7% vs 32% +/- 8%, P <.05). Among patients with reversible myocardial dysfunction, the rate pressure product (RPP) increased after revascularization (19,522 +/- 5474 vs 26,190 +/- 5610 mm Hg/min, P <.01), whereas the RPP did not change in patients with irreversible myocardial dysfunction (21,546 +/- 5450 and 22,774 +/- 8249 mm Hg/min). The number of PET viable segments was a predictor of the postoperative increase in the RPP in univariate (P <.04) and multivariate analyses (P <.001). In contrast, LDDE did not bear any prognostic information about improvement in the RPP.

CONCLUSIONS

This study confirms earlier findings of higher sensitivity and lower specificity of PET compared with LDDE in predicting improvement of regional left ventricular function after revascularization. However, the feasibility of predicting postrevascularization improvement of exercise parameters seems unique for PET. The potential prognostic value of this finding needs further investigation.

Normal values of regional left ventricular endocardial motion: multicenter color kinesis study

Our goal was to establish normal values for quantitative color kinesis indexes of left ventricular (LV) wall motion over a wide range of ages, which are required for objective diagnosis of regional systolic and diastolic dysfunction. Color-encoded images were obtained in 194 normal subjects (95 males, 99 females, age 2 mo to 79 yr) in four standard views. Quantitative indexes of magnitude and timing of systolic and diastolic function were studied for age- and gender-related differences. Normal limits of all ejection and filling indexes were in a narrow range (< or =25% of the mean), with no major gender-related differences. Despite invariable ejection fractions, both peak filling and ejection rates decreased with age (30 and 20%, correspondingly) with a concomitant increase in mean filling and ejection times, resulting in five- and twofold increases in the late to early filling and ejection ratios, correspondingly. Diastolic asynchrony increased with age (from 4.7 +/- 2.0 to 6.4 +/- 3.2 from the 2nd to 7th decade). The normal values of color kinesis indexes should allow objective detection of regional LV systolic and diastolic dysfunction.

Value of transesophageal dobutamine stress echocardiography in assessing coronary artery disease

The introduction of digital echocardiography has significantly enhanced our ability to select the best set of frames for analysis. However, despite the beneficial attributes of transthoracic dobutamine stress echocardiography, poor quality 2-dimensional images continue to be a significant limiting factor in patients with chest deformities, severe chronic obstructive lung disease, marked obesity, and previous chest surgery. Transesophageal echocardiography provides a new window to monitor left ventricular contractility without the interference of bone and air-filled structures of the thoracic cage. The transesophageal dobutamine stress test is a logical but poorly explored modality to image/stress the heart in certain patients with known or suspected myocardial ischemia. Overall sensitivity (< or = 85%) and specificity (< or = 95-100%) of transesophageal dobutamine stress echocardiography appear to be similar to that of previous transthoracic studies, although no direct comparison has been accomplished between transthoracic and transesophageal stress images. False negative transesophageal dobutamine stress echocardiography results have been described in patients with single-vessel disease in whom ischemic regions may not have been visualized throughout the entire study. False positive study results may be present in patients with hypertension and myocardial hypertrophy that may have signs and symptoms of myocardial ischemia in absence of obstructive disease of the epicardial coronary arteries, presumably related to either microvascular disease or impaired vasodilatory reserve. The proportion of patients with coronary artery disease who need a transesophageal examination for reliable assessment of echocardiographic response to stress varies depending on the operators' skills, the interpreters' experience, and the use of videotape or digitizing systems for image analysis. Although clinically useful in its present transthoracic and transesophageal form, a major limitation of dobutamine stress echocardiographic study is the subjective visual interpretation of endocardial motion and wall thickening, which is only semiquantitative. Color kinesis and tissue Doppler imaging (TDI) are 2 novel echocardiographic techniques that color code endocardial motion and myocardial velocity online and have the potential to objectively quantify regional left ventricular function. Quantitative standardization of transthoracic and transesophageal data interpretation, such as establishing endocardial motion by color kinesis or velocity thresholds by TDI for an abnormal segmental response to stress, has the potential to decrease interobserver variability and increase interinstitutional agreement.

Color Kinesis: New Technique or Just Another Display of Acoustic Quantification?

Color kinesis is a relatively new echocardiographic technique that allows color encoding of endocardial motion in real time. We briefly review the literature on the current clinical uses and limitations of this technique, as well as its potential future applications based on some of our results. The major advantage of this modality is that it provides the basis for objective and automated evaluation of regional systolic and diastolic function, which may have a direct impact on the diagnosis of various myocardial disease states and, in particular, coronary artery disease.