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L Weinert

Publications and source records attributed to L Weinert.

At least 19 recordsLinked to original sources
PubMed2006

Objective evaluation of changes in left ventricular and atrial volumes during parabolic flight using real-time three-dimensional echocardiography.

We tested the feasibility of real-time three-dimensional (3D) echocardiographic (RT3DE) imaging to measure left heart volumes at different gravity during parabolic flight and studied the effects of lower body negative pressure (LBNP) as a countermeasure. Weightlessness-related changes in cardiac function have been previously studied during spaceflights using both 2D and 3D echocardiography. Several technical factors, such as inability to provide real-time analysis and the need for laborious endocardial definition, have limited its usefulness. RT3DE imaging overcomes these limitations by acquiring real-time pyramidal data sets encompassing the entire ventricle. RT3DE data sets were obtained (Philips 7500, X3) during breath hold in 16 unmedicated normal subjects in upright standing position at different gravity phases during parabolic flight (normogravity, 1 Gz; hypergravity, 1.8 Gz; microgravity, 0 Gz), with LBNP applied (-50 mmHg) at 0 Gz in selected parabolas. RT3DE imaging during parabolic flight was feasible in 14 of 16 subjects. Data were analyzed (Tomtec) to quantify left ventricular (LV) and atrial (LA) volumes at end diastole and end systole, which significantly decreased at 1.8 Gz and increased at 0 Gz. While ejection fraction did not change with gravity, stroke volume was reduced by 16% at 1.8 Gz and increased by 20% at 0 Gz, but it was not significantly different from 1 Gz values with LBNP. RT3DE during parabolic flight is feasible and provides the basis for accurate quantification of LV and LA volume changes with gravity. As LBNP counteracted the increase of LV and LA volumes caused by changes in venous return, it may be effectively used for preventing cardiac dilatation during 0 Gz.

Adult↗
PubMed2005

Improved quantification of left ventricular mass based on endocardial and epicardial surface detection with real time three dimensional echocardiography.

OBJECTIVE: To develop a technique for volumetric analysis of real time three dimensional echocardiography (RT3DE) data aimed at quantifying left ventricular (LV) mass and to validate the technique against magnetic resonance (MR) assumed as the reference standard. DESIGN: RT3DE, which has recently become widely available, provides dynamic pyramidal data structures that encompass the entire heart and allows four dimensional assessment of cardiac anatomy and function. However, analysis techniques for the quantification of LV mass from RT3DE data are fundamentally two dimensional, rely on geometric modelling, and do not fully exploit the volumetric information contained in RT3DE datasets. Twenty one patients underwent two dimensional echocardiography (2DE), RT3DE, and cardiac MR. LV mass was measured from 2DE and MR images by conventional techniques. RT3DE data were analysed to semiautomatically detect endocardial and epicardial LV surfaces by the level set approach. From the detected surfaces, LV mass was computed directly in the three dimensional space as voxel counts. RESULTS: RT3DE measurement was feasible in 19 of 21 patients and resulted in higher correlation with MR (r = 0.96) than did 2DE (r = 0.79). RT3DE measurements also had a significantly smaller bias (-2.1 g) and tighter limits of agreement (2SD = +/-23 g) with MR than did the 2DE values (bias (2SD) -34.9 (50) g). Additionally, interobserver variability of RT3DE (12.5%) was significantly lower than that of 2DE (24.1%). CONCLUSIONS: Direct three dimensional model independent LV mass measurement from RT3DE images is feasible in the clinical setting and provides fast and accurate assessment of LV mass, superior to the two dimensional analysis techniques.

Echocardiography, Three-Dimensional↗
PubMed2004

Feasibility of real-time 3D echocardiography in weightlessness during parabolic flight.

Aim of the study was to test the feasibility of transthoracic real-time 3D (Philips) echocardiography (RT3D) during parabolic flight, to allow direct measurement of heart chambers volumes modifications during the parabola. One RT3D dataset corresponding to one cardiac cycle was acquired at each gravity phase (1 Gz, 1.8 Gz, 0 Gz, 1.8 Gz) during breath-hold in 8 unmedicated normal subjects (41 +/- 8 years old) in standing upright position. Preliminary results, obtained by semi-automatically tracing left ventricular (LV) and left atrial (LA) endocardial contours in multiple views (Tomtec), showed a significant (p<0.05) reduction, compared to 1 Gz, of LV and LA volumes with 1.8 Gz, and a significant increase with 0 Gz. Further analysis will focus on the right heart.

Adult↗
PubMed2001

Effects of aging on left atrial reservoir, conduit, and booster pump function: a multi-institution acoustic quantification study.

OBJECTIVE: To assess the feasibility of measuring left atrial (LA) function with acoustic quantification (AQ) and then assess the effects of age and sex on LA reservoir, conduit, and booster pump function. PATIENTS AND SETTING: 165 subjects without cardiovascular disease, 3-79 years old, were enrolled by six tertiary hospital centres. INTERVENTIONS: Continuous LA AQ area data were acquired and signal averaged to form composite waveforms which were analysed off-line. MAIN OUTCOME MEASURES: Parameters of LA performance according to age and sex. RESULTS: Signal averaged LA waveforms were sufficiently stable and detailed to allow automated analysis in all cases. An age related increase in LA area was noted. LA reservoir function did not vary with age or sex. All parameters of LA passive and active emptying revealed a significant age dependency. Overall, the passive emptying phase accounted for 66% of total LA emptying ranging from 76% in the youngest to 44% in the oldest decade. LA contraction accounted for 34% of atrial emptying in all subjects combined with the older subjects being more dependent on atrial booster pump function. When adjusted for atrial size, there were no sex related differences in LA function. CONCLUSIONS: LA reservoir, conduit, and booster pump function can be assessed with automated analysis of signal averaged LA area waveforms. As LA performance varies with age, establishment of normal values should enhance the evaluation of pathologic states in which LA function is important.

Acoustics↗
PubMed2000

Electronic transmission of digital echocardiographic studies: effects of MPEG compression.

The acquisition, storage and retrieval of digital echocardiographic studies greatly facilitates image review and quantitation and permits the transmission of studies electronically. However, the considerable size of digital echocardiographic data files makes transmission over existing networks slow and impractical. Reduction in the size of these data files can be accomplished with digital image compression. We sought to evaluate the effects of MPEG-1 compression on the transfer time of digital echocardiographic studies over currently available network connections. Ninety consecutive routine clinical echocardiographic studies were randomly compressed at one of three compression ratios 60:1, 80:1, or 120:1 and sent to a receiving terminal using simulated transmission rates. Compression of digital echocardiographic studies at these ratios which, have been shown to maintain diagnostic image quality, reduced the size of digital echocardiographic studies to less than 1% of their original sizes which allowed transmission of echocardiographic studies over networks using 3ISDN or T1 lines with minimal waiting time.

Echocardiography↗
PubMed2000

The role of echocardiographic harmonic imaging and contrast enhancement for improvement of endocardial border delineation.

Despite advances in imaging technology, many myocardial segments remain poorly visualized with echocardiography; however, both contrast enhancement and harmonic imaging have shown promise for improving endocardial definition. Fifty subjects with technically limited echocardiograms were studied with fundamental and harmonic imaging as well as during echocardiographic contrast injection. Overall endocardial visualization scores improved with both techniques compared with fundamental imaging. Harmonic imaging improved endocardial visualization in 43% of all segments and in 57% of segments nonvisualized with fundamental imaging. The benefit of harmonic imaging was seen in all segments. Contrast echocardiography had similar overall improvements in visualization (42% of all segments, 67% of segments nonvisualized with fundamental imaging) but was not helpful in all regions. Harmonic imaging outperformed contrast in 9 of 22 segments, whereas contrast was superior in 4 of 22. In a subgroup of patients with very poor images, contrast enhancement was superior, with a greater increase in overall score and a higher salvage rate than harmonic (68% vs 40%).

Albumins↗
PubMed2000

Effects of MPEG compression on the quality and diagnostic accuracy of digital echocardiography studies.

The advantages of digital echocardiography studies include ease of retrieval, review, comparison, duplication, and quantitation as well as the potential for moving studies over networks. However, the large amounts of data associated with digital echocardiography studies have posed new problems. Reduction of the amount of data can be accomplished with image compression, in particular MPEG-1 (Moving Pictures Expert Group), which is designed for dynamic image sequences. However the effects of different levels of compression on the quality and diagnostic content of echocardiographic images need to be established. Digital sequences of single cardiac cycles were acquired in 40 consecutive patients, MPEG-1-compressed at different effective ratios (60:1, 80:1, 120:1, 200:1, 300:1, 370:1, 500:1), reviewed, and scored for endocardial visualization. The overall visualization scores and percentages of nonvisualized segments in the compressed images were not different from the uncompressed images up to a compression ratio of 200:1. Differential effects of compression were noted on a segmental basis and also varied with baseline image quality. The ability to correctly identify regional wall motion abnormalities did not decrease until compression ratios of 1:200 or higher were used. Digital echocardiography loops, MPEG-1-compressed at an effective ratio of 200:1, demonstrate no degradation in endocardial visualization quality or diagnostic content. Compression at this ratio has the potential to reduce the storage size of digital echocardiography studies to less than 1% of their current size.

Echocardiography↗
PubMed2000

Power Doppler imaging as a basis for automated endocardial border detection during left ventricular contrast enhancement.

Echocardiographic evaluation of left ventricular (LV) systolic function relies on endocardial visualization, which can be improved when necessary using contrast enhancement. However, there is no method to automatically detect the endocardial boundary from contrast-enhanced images. We hypothesized that this could be achieved using harmonic power Doppler imaging. Twenty-two patients were studied in two protocols: (1) 11 patients with poorly visualized endocardium (> 3 contiguous segments not visualized) and (2) 11 consecutive patients referred for dobutamine stress echocardiography who were studied at rest and at peak dobutamine infusion. Patients were imaged in the apical four-chamber view using harmonic power Doppler mode (HP SONOS 5500) during LV contrast enhancement (Optison or Definity DMP115). Digital images were analyzed using custom software designed to automatically extract the endocardial boundary from power Doppler color overlays. LV cavity area was automatically measured frame-by-frame throughout the cardiac cycle, and fractional area change calculated and compared with those obtained by manually tracing the endocardial boundary in end-systolic and end-diastolic gray scale images. Successful border detection and tracking throughout the cardiac cycle was possible in 9 of 11 patients with poor endocardial definition and in 10 of 11 unselected patients undergoing dobutamine stress testing. Fractional area change obtained from power Doppler images correlated well with manually traced area changes (r = 0.82 and r = 0.97, in protocols 1 and 2, respectively). Harmonic power Doppler imaging with contrast may provide a simple method for semi-automated border detection and thus facilitate the objective evaluation of LV function both at rest and under conditions of stress testing. This methodology may prove to be particularly useful in patients with poorly visualized endocardium.

Contrast Media↗
PubMed2000

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.

Adolescent↗
PubMed1999

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

OBJECTIVES: To test the feasibility of objective and automated evaluation of echocardiographic stress tests, we studied the ability of segmental analysis of color kinesis (CK) images to detect dobutamine-induced wall motion abnormalities and compared this technique with inexperienced reviewers of conventional gray-scale images. BACKGROUND: Conventional interpretation of stress echocardiographic studies is subjective and experience dependent. METHODS: CK images were obtained in 89 of 104 consecutive patients undergoing clinical dobutamine stress studies and were analyzed using custom software to calculate regional fractional area change in 22 segments in four standard views. Each patient's data obtained at rest was used as a control for automated detection of dobutamine-induced wall motion abnormalities. Independently, studies were reviewed without CK overlays by two inexperienced readers who classified each segment's response to dobutamine. A consensus reading of two experienced reviewers was used as the gold standard for comparisons. In a subgroup of 16 patients, these consensus readings and CK detection of wall motion abnormalities were compared with coronary angiography. RESULTS: The consensus reading detected ischemic response to dobutamine in 43 of 1958 segments in 23 of 89 patients. Automated detection of stress-induced wall motion abnormalities correlated more closely with the standard technique than the inexperienced reviewers (sensitivity 0.76 vs. 0.55, specificity 0.98 vs. 0.94 and accuracy 0.97 vs. 0.92). When compared with coronary angiography in a subgroup of patients, analysis of CK images differentiated between normal and abnormal wall motion more accurately than expert readers of gray-scale images (accuracy of 0.93 vs. 0.82). CONCLUSIONS: Analysis of CK images allows fast, objective and automated evaluation of regional wall motion, sensitive enough for clinical dobutamine stress data and more accurate than inexperienced readers. This method may result in a valuable adjunct to conventional visual interpretation of dobutamine stress echocardiography.

Aged↗
PubMed1999

Calcified right atrial mass in a woman receiving long-term intravenous phosphate therapy.

Right atrial masses are easily seen by 2-dimensional echocardiography and may represent primary tumors, secondary tumor invasion of the right atrium, tricuspid valve vegetations, or atrial thrombi. Calcification of right atrial masses is uncommon but easily identified by 2-dimensional echocardiography because of the high echogenicity of calcium deposits. We describe a patient with a heavily calcified right atrial thrombus caused by an indwelling central venous catheter and long-term intravenous phosphate infusion.

Calcinosis↗
PubMed1999

Identification of cardiac masses and abnormal blood flow patterns with harmonic power Doppler contrast echocardiography.

Power Doppler is an ultrasound technique that color-encodes the change in amplitude of the ultrasound signal, which reflects changes in the position of scatterers between ultrasound pulses. Power Doppler can be used with echocardiographic contrast agents in a harmonic imaging mode to opacify a cardiac chamber. The opacification of a cardiac chamber can aid in visualizing the silhouette of intracardiac masses and displaying blood flow patterns. Four cases are presented that demonstrate the use of harmonic power Doppler to aid in the identification of a left ventricular apical thrombus, a left atrial thrombus, and a left ventricular pseudoaneurysm.

Aged↗
PubMed1999

Effect of age, heart rate and tricuspid regurgitation on the Doppler echocardiographic evaluation of right ventricular diastolic function.

Pulsed-wave Doppler analysis of tricuspid inflow and hepatic venous flow allows the determination of multiple parameters of right-ventricular (RV) diastolic function. This study sought to evaluate the influence of heart rate, age and tricuspid regurgitation on Doppler parameters of RV diastolic performance. We studied 80 subjects (20 normal and 60 with RV pathology) with Doppler recordings of the tricuspid inflow and hepatic vein. All tricuspid Doppler parameters were dependent on heart rate, age or regurgitation severity as were the hepatic vein S wave, S/D ratio and systolic filling fraction. The atrial reversal velocity in the hepatic vein Doppler tracing was not affected by age, heart rate or regurgitation. In addition, the inspiratory increase in this parameter was significantly elevated in RV pathologic states. This study demonstrates that most Doppler echocardiographic parameters of RV diastolic performance are dependent on age, tricuspid regurgitation or heart rate.

Adult↗
PubMed1999

Quantitative assessment of regional right ventricular function with color kinesis.

We used color kinesis, a recent echocardiographic technique that provides regional information on the magnitude and timing of endocardial wall motion, to quantitatively assess regional right ventricular (RV) systolic and diastolic properties in 76 subjects who were divided into five groups, as follows: normal (n = 20), heart failure (n = 15), pressure/volume overload (n = 14), pressure overload (n = 12), and RV hypertrophy (n = 15). Quantitative segmental analysis of color kinesis images was used to obtain regional fractional area change (RFAC), which was displayed in the form of stacked histograms to determine patterns of endocardial wall motion. Time curves of integrated RFAC were used to objectively identify asynchrony of diastolic endocardial motion. When compared with normal subjects, patients with pressure overload or heart failure exhibited significantly decreased endocardial motion along the RV free wall. In the presence of mixed pressure/volume overload, the markedly increased ventricular septal motion compensated for decreased RV free wall motion. Diastolic endocardial wall motion was delayed in 17 of 72 segments (24%) in patients with RV pressure overload, and in 31 of 90 segments (34%) in patients with RV hypertrophy. Asynchrony of diastolic endocardial wall motion was greater in the latter group than in normal subjects (16% versus 10%: p < 0.01). Segmental analysis of color kinesis images allows quantitative assessment of regional RV systolic and diastolic properties.

Adult↗
PubMed1998

Quantitative evaluation of global and regional left ventricular diastolic function with color kinesis.

BACKGROUND: Diastolic wall motion asynchrony is a major determinant of impaired left ventricular (LV) filling in patients with concentric hypertrophy and coronary artery disease. We evaluated the ability of Color Kinesis, a new echocardiographic technique that color-encodes endocardial motion, to quantitatively assess global and regional LV filling properties. METHODS AND RESULTS: Color Kinesis images and mitral and pulmonary vein flow Doppler data were acquired in 29 patients with LV hypertrophy and 29 age-matched control subjects. In addition, Color Kinesis data were correlated to coronary angiographic findings in 15 patients with suspected coronary artery disease. Segmental analysis of Color Kinesis images was used to obtain time histograms of regional diastolic fractional area change, wherein early and late peaks (peaks 1 and 2) reflected rapid LV filling and atrial contraction, respectively. Regional mean LV filling time and filling curves were used to objectively identify diastolic endocardial motion asynchrony in patients with LV hypertrophy and coronary artery disease. None of the mitral and pulmonary vein Doppler indices differentiated patients with normalized mitral Doppler profile (n=13) from control subjects, whereas reduced peak1/peak2 ratio and prolonged mean filling time indicated augmented contribution of atrial contraction toward LV filling (P<.05). In 22 of 25 patients with LV hypertrophy and preserved systolic function and in all patients with coronary artery disease, delayed diastolic endocardial motion was observed in at least one segment. CONCLUSIONS: Analysis of Color Kinesis images provides objective assessment of global and regional LV filling properties and allows identification of both diastolic dysfunction in patients with normalized Doppler indices and wall motion asynchrony.

Adult↗