Improvement in Endocardial Border Delineation Using Tissue Harmonic Imaging

Background and Methods: For years, tissue has been assumed to be a linear medium in diagnostic ultrasound applications; thus, no backscattered signals in the second harmonic band are expected in harmonic imaging without the injection of a contrast agent. However, it has been shown that a useful tissue image is formed even without a contrast agent. The aim of this study was to evaluate whether this tissue harmonic image provided improved visualization of endocardial borders. Fifty-six adult patients with various heart diseases were investigated using conventional two-dimensional echocardiography and tissue harmonic imaging. In 30 of these patients, the left ventricular endocardial borders were well defined in the standard parasternal and apical views using conventional two-dimensional echocardiography. In the remaining 26 patients, delineation of endocardial borders was not possible in at least two segments. The equipment used was an ATL HDI-3000 diagnostic system equipped with harmonic imaging. Results: In all 56 patients, the myocardium and valves could be imaged with tissue harmonic imaging. Harmonic recordings were sharper and contained fewer clutter artifacts than conventional recordings. Most striking was the enhancement of left ventricular endocardial borders. In the 26 patients with incomplete delineation of left ventricular endocardial borders, wall motion could be evaluated in 290 of 312 (93%) segments with tissue harmonic imaging compared with only 168 of 312 (54%) segments with conventional echocardiography (P < 0.001). Conclusions: Tissue harmonic imaging improves image quality and can be used to enhance the definition of left ventricular endocardial borders. These findings can be explained by the nonlinear propagation of ultrasound within the tissue, which results in distortion of the transmitted signal and, thus, harmonic generation.     

Detection of left ventricular endocardial border with tissue harmonic imaging

BACKGROUND: Ultrasonic wave propagation in human tissues is not linear. As a consequence, harmonic waves, whose frequency is a multiple (harmonic) of the emitted frequency, are generated. Tissue Harmonic Imaging (THI) processes only the second harmonic frequency in order to improve the signal-to-noise ratio of the received signal. The study was aimed at investigating the impact of THI on the detection of the Left Ventricular (LV) endocardial border. Attention was paid to determine which LV walls were analysed more clearly with THI rather than with conventional Fundamental Frequency Imaging (FFI). METHODS: We compared the FFI and the THI visualization of the 16 LV segments and of the 6 LV walls in 30 consecutive patients by scoring the images as bad, sufficient or good. The equipment used was a GE Vingmed System Five (Orten, Norway). RESULTS: Images were good in 85% of segments explored with THI, whereas FFI provided good images in 47% of segments (p<0.001). From the apical window, visualization of the apex, lateral wall and anterior wall significantly improved with THI; using the parasternal approach, imaging of posterior wall was definitely better with THI than with FFI. CONCLUSIONS: THI enhances both endocardial visualization and global image quality. Tech-nical development, however, increases the diagnostic possibilities of echocardiography but does not substitute the operator's experience.     

Two-dimensional echocardiographic detection of left ventricular posterior wall motion abnormalities using an inferior angulation view

Two-dimensional echocardiography is frequently used to detect left ventricular (LV) wall motion abnormalities. Modification of the apical 4-chamber view by inferior angulation of the transducer provides a superior image for detection of regional wall motion abnormalities of the LV posterior wall. The inferior angulation image was prospectively compared with the standard parasternal short-axis image for detection of posterior LV wall motion abnormalities as defined by contrast left ventriculography in 63 consecutive patients. Posterior wall akinesia was present on the contrast left ventriculogram in 22 of the 63 patients. The parasternal short-axis image was judged technically inadequate for interpretation in 7 patients (11%). The inferior angulation image was technically adequate for interpretation in all patients. The sensitivity, specificity and accuracy of the inferior angulation image for detection of LV posterior wall motion abnormality was 91%, 80% and 84%, respectively, vs 67%, 71% and 70% for the parasternal short-axis image. The differences between the sensitivity, specificity and accuracy for the 2 views were not statistically significant. These observations indicate that the inferior angulation image provides a useful plane for routine echocardiographic analysis of regional LV wall motion either as a primary method to detect posterior wall motion abnormality or as a confirmatory view to document posterior wall motion abnormality.     

Contrast and harmonic imaging improves accuracy and efficiency of novice readers for dobutamine stress echocardiography

BACKGROUND: Newer contrast agents as well as tissue harmonic imaging enhance left ventricular (LV) endocardial border delineation, and therefore, improve LV wall-motion analysis. Interpretation of dobutamine stress echocardiography is observer-dependent and requires experience. This study was performed to evaluate whether these new imaging modalities would improve endocardial visualization and enhance accuracy and efficiency of the inexperienced reader interpreting dobutamine stress echocardiography. METHODS AND RESULTS: Twenty-nine consecutive patients with known or suspected coronary artery disease underwent dobutamine stress echocardiography. Both fundamental (2.5 MHZ) and harmonic (1.7 and 3.5 MHZ) mode images were obtained in four standard views at rest and at peak stress during a standard dobutamine infusion stress protocol. Following the noncontrast images, Optison was administered intravenously in bolus (0.5-3.0 ml), and fundamental and harmonic images were obtained. The dobutamine echocardiography studies were reviewed by one experienced and one inexperienced echocardiographer. LV segments were graded for image quality and function. Time for interpretation also was recorded. Contrast with harmonic imaging improved the diagnostic concordance of the novice reader to the expert reader by 7.1%, 7.5%, and 12.6% (P < 0.001) as compared with harmonic imaging, fundamental imaging, and fundamental imaging with contrast, respectively. For the novice reader, reading time was reduced by 47%, 55%, and 58% (P < 0.005) as compared with the time needed for fundamental, fundamental contrast, and harmonic modes, respectively. With harmonic imaging, the image quality score was 4.6% higher (P < 0.001) than for fundamental imaging. Image quality scores were not significantly different for noncontrast and contrast images. CONCLUSION: Harmonic imaging with contrast significantly improves the accuracy and efficiency of the novice dobutamine stress echocardiography reader. The use of harmonic imaging reduces the frequency of nondiagnostic wall segments.     

Impact of harmonic imaging and transducer frequency on 'ventricular volume' measurements using real-time three-dimensional echocardiography: studies in an in vitro model.

AIMS: Harmonic imaging has increased the yield of quantifiable scans in two-dimensional echocardiography. Although real-time three-dimensional echocardiography avoids geometric assumptions in volume analysis, accurate measurement can be limited by image quality. This study compared volumes from a balloon model mimicking the left ventricle, scanned with and without harmonic imaging, using real time three-dimensional echocardiography. METHODS: Two balloons separated by ultrasound gel were suspended in a water bath. To mimic different chamber volumes, 12 volumes of water within the inner balloon (40-180ml) were scanned using a 3.5MHz probe at fundamental frequency and using a 2.5MHz probe with and without harmonic imaging. RESULTS: Scanning at 3.5MHz, the long axis (B) scans did not significantly underestimate the balloon volume but the 'short axis' (C) scans did (mean difference from actual volumes -0.7-1.4ml, P=0.14 - 3.9 +/- 1.2 ml,P < 0.0001 for B and C scans, respectively). Scanning at 2.5MHz both B and C scans significantly underestimated even more the true volume, C scans to a greater extent (mean difference -6.9 +/- 2.4ml and -11.2 +/- 4.0ml for B and C scans respectively,P < 0.0001 in both cases). However with harmonic imaging, transmitting at 1.7MHz and receiving at 2-4MHz, there was no significant difference of either B or C scans from the reference values (mean difference of B scans -1.2 +/- 1.9ml, P=0.06 and C scans -0.6 +/- 2.2ml, P=0.4). CONCLUSION: The enhanced resolution provided by harmonic imaging improves accuracy of volume analysis by real-time three-dimensional echocardiography.     

Comparison of tissue harmonic imaging and standard imaging in echocardiography based on 4 different emission frequencies

Harmonic imaging is an innovative technique which is now available in most of the echographic equipment currently on the market. The use of echographic contrast agents led to the introduction of this particular technology, which has largely superseded the former method. In everyday medical practice, it seems to provide a better definition of endocardial contours. In this article, the authors have described a prospective study including 32 patients with an average age of 64 years (+/- 5 years). The aim was to compare imaging quality obtained by 2 acquisition frequencies for standard imaging with that procured by harmonic imaging (emission and reception frequency, 2.5 and 3.3 MHz respectively for the former technique; emission and reception frequency, 1.7 and 2.2 MHz respectively for the latter). The overall scores given by 2 different examiners for emission and reception frequency were as follows: 3.28 and 3.15 for 2.5 MHz, 2.84 and 2.56 for 3.3 MHz regarding the standard technique; 2.56 and 3.031 for 1.7 MHz and 2.56 and 2.063 for 2.2 MHz for the harmonic imaging technique. The superior performance of tissue harmonic imaging has been confirmed in the endocardial study of the left ventricular segments and in the analysis of the mitral valve. This study shows that harmonic imaging, a technique which was easy to use in the present study, provides a means of obtaining an average level of ultrasound imaging that facilitates the interpretation of the clinical picture.     

Accuracy of measurement of left ventricular volume and ejection fraction by new real-time three-dimensional echocardiography in patients with wall motion abnormalities secondary to myocardial infarction

Three-dimensional echocardiography is an ideal tool for the measurement of left ventricular (LV) volume because no geometric assumptions about LV shape are needed. The introduction of new real-time 3-dimensional echocardiography (RT3DE) has allowed rapid acquisition of a 3-dimensional dataset with good image quality. The purpose of this study was to examine the accuracy of RT3DE for the measurement of LV volume and ejection fraction in patients with wall motion abnormalities by using quantitative gated single-photon emission computed tomography (QGSPECT) as a reference standard. The study population consisted of 25 consecutive patients with wall motion abnormalities who underwent LV volume measurement by 2-dimensional echocardiography and by QGSPECT. LV volume and ejection fraction by RT3DE were measured offline by using the average rotation method. In 23 of 25 patients (92%), it was possible to measure 3-dimensional volume with RT3DE. RT3DE correlated well with QGSPECT in the measurement of end-diastolic volume and end-systolic volume (r = 0.97, mean difference 3.4 ml; r = 0.98, mean difference 2.0 ml, respectively), 2-dimensional echocardiography also correlated with QGSPECT but underestimated LV volume (r = 0.98, mean difference 21.1 ml; r = 0.98, mean difference 15.6 ml, respectively). Ejection fraction obtained by RT3DE had better agreement with that obtained by QGSPECT than that obtained by 2-dimensional echocardiography (r = 0.92, mean difference -0.2%; r = 0.89, mean difference -2.7%, respectively). RT3DE allows convenient and accurate estimation of LV volume and ejection fraction in patients with wall motion abnormalities.     

Clinical Benefits of Using Second Generation Ultrasound Contrast Agents in Stress Echocardiography

Stress echocardiography is an established and widely used method for the noninvasive detection of myocardial ischemia. However, despite introduction of new echocardiographic technologies, such as harmonic imaging, unsatisfactory image quality limits an accurate interpretation of left ventricular (LV) wall thickening and motion in up to 30% of patients during stress echocardiography. Development and availability of second generation transpulmonary contrast agents, which opacify the LV chamber and have the capability of enhancing endocardial border definition, facilitate high-quality imaging of LV structures even in technically difficult patients. Application of a contrast agent is not associated with significant extra cost of time and manipulations because bolus injections are sufficient in most instances and harmonic imaging capabilities as well as contrast specific presets are implemented and, thus, readily available in most modern ultrasound systems. Numerous studies have demonstrated that contrast echocardiography substantially improves LV cavity visualization at rest as well as at peak stress and, therefore, increases reader confidence and decreases interobserver variability. Moreover, enhanced learning curves for interpreting stress echocardiograms have been reported in novice readers. It has been reported that compared with native stress echocardiography the use of contrast results in identification of more true positive as well as true negative results and helps to avoid unnecessary invasive procedures in a considerable number of patients. Contrast stress echocardiography may, therefore, also prove cost effective in the future. Further refinements of contrast agent properties and new developments in imaging technology will likely continue to extend the spectrum of diagnostic cardiac imaging techniques and further enhance noninvasive assessment of the complex pathophysiology of coronary artery disease. (ECHOCARDIOGRAPHY, Volume 20, Supplement 1, 2003)     

Contrast echocardiography is superior to tissue harmonics for assessment of left ventricular function in mechanically ventilated patients

BACKGROUND: Assessment of left ventricular function by echocardiography is frequently challenging in mechanically ventilated patients. We evaluated the potential value of contrast-enhanced imaging and tissue harmonic imaging over standard fundamental imaging for endocardial border detection (EBD) in these patients. METHODS AND RESULTS: Fifty patients underwent standard transthoracic 2D echocardiography and were imaged in fundamental and tissue harmonic modes and subsequently with intravenous contrast (Optison). Two echocardiographers reviewed all studies for ease of visualization of endocardial border segments and scoring of wall motion. EBD for each wall segment was graded from 1 to 4 (1 = excellent EBD). Wall motion was scored by a standard 16-segment model and 1 to 5 scale. Studies were categorized as nondiagnostic if 4 of 6 segments in the apical 4-chamber view were either poorly seen or not seen (EBD score 3 or 4). Quantification of ejection fraction was independently performed offline. Visualization of 68% of all segments improved with contrast echocardiography versus 17% improvement with tissue harmonics compared with fundamental mode. Significant improvement (poor/not seen to good/excellent) occurred in 60% of segments with contrast echocardiography versus 18% with tissue harmonics. A total of 850 segments were deemed poor/not seen, 78% of which improved to good/excellent with contrast echocardiography versus 23% with tissue harmonics. Interobserver agreement on EBD was 64% to 70%. Conversion of nondiagnostic to diagnostic studies occurred in 85% of patients with contrast echocardiography versus 15% of patients with tissue harmonics. Scoring of wall motion with fundamental mode, tissue harmonics, and contrast echocardiography was possible in 61%, 74%, and 95% of individual segments, respectively (P <.001). Wall motion scoring was altered in 17% of segments with contrast echocardiography and in 8% with tissue harmonics. Interobserver agreement on wall motion scoring was 84% to 88%. Contrast echocardiography permitted measurement of ejection fraction 45% (P =.003) more often over fundamental mode versus a 27% (P =.09) increase with tissue harmonics. CONCLUSIONS: Contrast echocardiography is superior to tissue harmonic imaging for EBD, wall motion scoring, and quantification of ejection fraction in mechanically ventilated patients.     

Non-contrast second harmonic imaging improves interobserver agreement and accuracy of dobutamine stress echocardiography in patients with impaired image quality

OBJECTIVE: To examine the influence of second harmonic imaging during dobutamine echocardiography on regional endocardial visibility, interobserver agreement in the interpretation of wall motion abnormalities, and diagnostic accuracy in patients with reduced image quality. DESIGN: Blinded comparison. SETTING: Tertiary care centre. PATIENTS: 103 consecutive patients with suspected coronary artery disease and impaired transthoracic image quality (>/= 2 segments with poor endocardial delineation). METHODS: Fundamental and second harmonic imaging were performed at each stage of a dobutamine stress echocardiography. Coronary angiography was undertaken within three weeks of dobutamine echocardiography in 75 patients. MAIN OUTCOME MEASURES: Evaluation of regional endocardial visibility (scoring from 0 = poor to 2 = good) and of segmental wall motion abnormalities for both modalities separately. A second blinded examiner analysed 70 studies to determine interobserver agreement. RESULTS: Mean (SD) visibility score for all segments was 1.2 (0.4) using fundamental imaging and 1.7 (0.2) using second harmonic imaging at rest (p < 0.001), and 1.1 (0.4) v 1.6 (0.3), respectively, at peak dobutamine dose (p < 0.001). The average number of segments with poor endocardial visibility was lower for second harmonic than for fundamental imaging (0.6 (1.1) v 3.8 (2.6) at rest, p < 0.001; 0.9 (1.3) v 4.3 (2.9) at peak dose, p < 0.001). Improvement was most pronounced in all lateral and anterior segments. The kappa value for identical study interpretation increased from 0. 40 to 0.69 (p < 0.05). Sensitivity for the diagnosis of coronary artery disease was 64% using fundamental imaging versus 92% using harmonic imaging (p < 0.001), while specificity remained unchanged at 75% for both imaging modalities. CONCLUSIONS: Second harmonic imaging enhances endocardial visibility during dobutamine echocardiography. Consequently, interobserver agreement on stress echocardiography interpretation and diagnostic accuracy are significantly improved compared to fundamental imaging. Thus, in difficult to image patients, dobutamine echocardiography should be performed using second harmonic imaging.     

Einflu? der Bildqualit?t auf die Genauigkeit der nichtinvasiven Isch?miediagnostik mit der Dobutamin-Stre?magnetresonanztomographie im Vergleich zur Dobutamin-Stre?echokardiographie

The analysis of wall motion abnormalities with dobutamine stress echocardiography is an established method for the detection of myocardial ischemia. With ultrafast magnetic resonance tomography, the application of identical stress protocols as used for echocardiography is possible. In 208 consecutive patients (147 M, 61 F) with suspected coronary artery disease, dobutamine stress echocardiography partially using harmonic imaging and dobutamine stress magnetic resonance tomography (DSMR) were performed prior to cardiac catheterization. DSMR images were acquired during short breath holds in 3 short axis-, a 4-, and a 2-chamber view using a turbo gradient echo technique. Patients were examined at rest and during a standard dobutamine-atropine scheme until submaximal heart rate was reached. Regional wall motion was assessed in a 16 segment model. Significant coronary heart disease was defined as angiographic >/=50% diameter stenosis. With DSMR, significantly more patients yielded very good (69%) or good (13%) image quality in comparison with dobutamine stress echocardiography (20% and 31%, p<0. 05). Moderate image quality occurred in 16% with MR and 41% with dobutamine stress echocardiography (p<0.05), 2% and 8% were non-diagnostic. With each technique 18 patients could not be examined (DSE: emphysema: 10, adipositas: 8, DSMR: claustrophobia: 11, adipositas: 6, contraindication: 1). Four patients did not reach target heart rate. In 107 patients, significant coronary artery disease was found. With DSMR sensitivity was 88.7% (dobutamine stress echocardiography: 74.3%; p<0.05) and specificity 85.7% (dobutamine stress echocardiography: 69.8%; p <0.05). This difference was most pronounced in the group with moderate echocardiographic image quality. High dose DSMR is superior to dobutamine stress echocardiography and can replace this technique especially in patients with moderate echocardiographic image quality.     

Tissue harmonic imaging: experimental analysis of the mechanism of image improvement

Tissue harmonic scanning visually improves echocardiographic image quality. The aim of the present study was to objectively assess the improvement in harmonic image quality under controlled laboratory conditions. A tissue-mimicking phantom that contained 8-mm-diameter cystic lesions at depths ranging from 2 to 12 cm was used. Harmonic scans (1.7 MHz transmit, 3.4 MHz receive) of the phantom were obtained and lesion detectability was compared to that in scans acquired with 2 fundamental frequencies (2.0 and 3.3 MHz). A 2 cm-thick ethanol layer was also used to simulate the nonlinear effect of human fat. Cyst detectability was quantified by measurement of the contrast-to-speckle ratio (CSR). The results indicated no significant difference in the CSR between harmonic and fundamental images obtained without the ethanol layer. With images obtained with the ethanol layer, a relative increase of the CSR during harmonic imaging was observed with respect to fundamental imaging (p<0.05). In conclusion, a fat layer, here simulated by ethanol, plays a significant role in determining the resulting image quality. Without this layer, the contribution of the second harmonic mode was not significant. Thus, in a slim patient, the harmonic mode may not be as beneficial to image improvement as in an obese patient.     

Tissue harmonic imaging: is it useful in hepatobiliary and pancreatic ultrasonography?

The introduction of tissue harmonic imaging (THI) could solve problems related to ultrasound in technically difficult patients by providing a marked improvement in image quality. Tissue harmonics are generated by tissue vibration while the transmitted pulse propagates through tissue and are multiples of the fundamental frequency. The harmonic image is obtained by separating the fundamental and harmonic frequencies, the second harmonic, or twice the fundamental frequency, being used for imaging. Through a better spatial resolution, less artifact and an increased visualization of the deep structures, tissue harmonic sonography improves the image quality. In hepatobiliary diseases THI improves the detection and characterisation of focal liver lesions, increases the conspicuity of gallbladder polyps and stones, choledocholithiasis and intrabiliary masses. Visualization of the pancreatic duct, pancreatic calcifications or duct stones is also more accurate with THI. The results with THI are better than those with conventional ultrasonography as the body mass index increases. The limitations of THI can be overcome by the use of the new pulse inversion harmonic imaging.     

Comparison of tissue harmonic imaging with contrast (sonicated albumin echocardiography and Doppler myocardial imaging for enhancing endocardial border resolution

Endocardial resolution during 2-dimensional echocardiography is technically limited in at least 10% to 15% of patients. Recently, several ultrasound imaging innovations have been introduced that may improve endocardial resolution and decrease the proportion of technically difficult studies. This study compares tissue harmonic imaging, intravenous sonicated albumin, and Doppler myocardial imaging in patients with technically difficult echocardiograms. Twenty-eight patients with known or suspected cardiac disease and poor baseline endocardial resolution were studied. Only harmonic imaging (conventional and optimized for tissue) was superior to baseline fundamental imaging (p <0.001). Harmonic imaging was superior to baseline imaging in all myocardial regions and in the majority of patients, including those with the worst baseline studies.     

Myocardial perfusion by contrast echocardiography: diagnosis of coronary artery disease using contrast-enhanced stress echocardiography and assessment of coronary anatomy and flow reserve

The advent of intravenous contrast agents, and newer ultrasound technology to enhance their detection, promises to improve and augment our conventional stress echocardiographic practice by improving diagnostic accuracy and providing novel information regarding myocardial perfusion and functional assessment of the coronary vasculature. The combination of intravenous contrast and harmonic stress echocardiography is a powerful tool for improved wall motion analysis through enhanced image quality, routinely permitting the evaluation of patients with suboptimal images. In this era of cost containment, we await studies in large populations addressing resource utilization and cost-effectiveness to determine if, indeed, all patients presenting with stress echocardiography should receive contrast. Myocardial perfusion can be observed using the technique, but the complex interactions of microbubbles and ultrasound in patients must be understood more fully before its implementation becomes routine practice. Non-invasive imaging of coronary arteries using contrast-enhanced transthoracic harmonic echo/Doppler promises to expand the field of diagnostic and experimental echocardiography, bringing new insight into the pathophysiology of ischemic and non-ischemic heart disease. The continued development of newer contrast agents and refinement of ultrasound imaging equipment ensures that the applications of contrast echocardiography in the assessment of CAD will continue to increase.     

Relation between number of component views and accuracy of left ventricular mass determined by three-dimensional echocardiography

Three-dimensional echocardiography (3DE) allows the accurate determination of left ventricular (LV) mass, but the optimal number of component or extracted 2-dimensional (2D) image planes that should be used to calculate LV mass is not known. This study was performed to determine the relation between the number of 2D image planes used for 3DE and the accuracy of LV mass, using cardiovascular magnetic resonance (CMR) imaging as the reference standard. Three-dimensional echocardiography data sets were analyzed using 4, 6, 8, 10 and 20 component 2D planes as well as biplane 2D echocardiography and CMR in 25 subjects with a variety of LV pathologies. Repeated-measures analysis of variance and the Bland-Altman method were used to compare measures of LV mass. To further assess the potential clinical impact of reducing the number of component image planes used for 3DE, the number of discrepancies between CMR and each of the 3DE estimates of LV mass at prespecified levels (i.e., > or =5%, > or =10%, and > or =20% difference from CMR LV mass) was tabulated. The mean LV mass by magnetic resonance imaging was 177 +/- 56 g (range 91 to 316). Biplane 2-dimensional echocardiography significantly underestimated CMR LV mass (p <0.05), but LV mass by 3DE was not statistically different from that by CMR regardless of the number of planes used. However, error variability and Bland-Altman 95% confidence intervals decreased with the use of additional image planes. In conclusion, transthoracic 3DE measures LV mass more accurately than biplane 2-dimensional echocardiography when > or =6 component 2D image planes are used. The use of >6 planes further increases the accuracy of 3DE, but at the cost of greater analysis time and potentially increased scanning times.     

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.     

Assessment of left ventricular aneurysm resectability by two-dimensional echocardiography

Mortality of surgical resection of a left ventricular (LV) aneurysm is largely determined by size and function of nonaneurysmal or residual myocardium. A residual myocardial index was determined using 2-dimensional echocardiography (2-D echo) in 56 consecutive patients scheduled for LV aneurysmectomy, and these results were correlated with surgical outcome. The index was calculated using 3 apical cross sections: the 2- and 4-chamber views and the long-axis view. These views were recorded at mutual angles of 60 degrees. In each view the end-diastolic length of normally moving endocardium of the 2 opposite walls was expressed as a fraction of the end-diastolic LV long axis. The index was assessed by averaging the 6 ratios obtained. In 41 survivors the index ranged from 40 to 71% (mean +/- standard deviation 53 +/- 7.8) and in 15 nonsurvivors from 29 to 67% (mean 38 +/- 8.5, p less than 0.01). With 1 exception, this echocardiographic index sharply separated survivors from nonsurvivors. The lower limit to survive aneurysmectomy was 40%.     

Use of harmonic echocardiographic contrast imaging and intravenous bolus of Levovist for evaluation of the left ventricle

Harmonic imaging is a new imaging modality using nonlinear acoustic response, which is particularly sensitive for the particles of contrast agents. Our study was designed to compare the potential of harmonic echocardiographic imaging of the left ventricle using a contrast agent, Levovist to improve the detection of endocardium in patients with suboptimal image quality. 40 patients were studied using standard transthoracic apical views of the left ventricle patients using fundamental frequency and second harmonic frequency after and intravenous injection of 2.5 g Levovist. The quality of endocardial delineation in 16 standard segments was scored from 0 to 2. Endocardial visualization index was calculated as a mean of the scores to express overall diagnostic quality. Harmonic imaging with contrast significantly improved left ventricular endocardial border detection (endocardial visualization index at baseline 1.24 +/- 0.41, with contrast 1.63 +/- 0.38; p < 0.001). The improvement was qualitatively observed in all parts of the left ventricle: in apex (2.4 +/- 0.8), in the middle part (2.5 +/- 0.9) and slightly less in the basal part (2.1 +/- 1.1) as scored on a 0-3 scale. The number of invisible segments decreased from 124 (fundamental) to 50 in contrast harmonic mode. The persistence of the contrast enhancement, prolonged in harmonic as compared to fundamental imaging (284 +/- 136s vs 117 +/- 87s; p < 0.001) enabled convenient recording of all necessary views. Harmonic imaging after an intravenous injection of Levovist significantly improves the visualization of left ventricular endocardial border. Prolonged contrast effect after a single bolus enhances the pertinence of the method in clinical practice.     

Usefulness of contrast echocardiography for assessment of left ventricular thrombus after acute myocardial infarction

Fifty consecutive patients referred to a coronary care unit for acute anterior myocardial infarction with ST-segment elevation underwent coronary arteriography, left ventricular (LV) angiography, and revascularization. Transthoracic echocardiography was systematically performed using fundamental imaging, second harmonic imaging, and contrast agents to assess the LV chamber. Six patients (12%) presented with a confirmed LV mural thrombus. Thirty-five percent of patients with time to revascularization>3 hours presented with an LV mural thrombus versus 0 patients with time to revascularization3 hours.