Biomedical subjects

W B Vletter

Publications and source records attributed to W B Vletter.

At least 19 recordsLinked to original sources

PubMed2006

Rapid and accurate measurement of left ventricular function with a new second-harmonic fast-rotating transducer and semi-automated border detection.

Measurement of left ventricular (LV) volume and function are the most common clinical referral questions to the echocardiography laboratory. A fast, practical, and accurate method would offer important advantages to obtain this important information. To validate a new practical method for rapid measurement of LV volume and function. We developed a continuous fast-rotating transducer, with second-harmonic capabilities, for three-dimensional echocardiography (3DE). Fifteen cardiac patients underwent both 3DE and magnetic resonance imaging (reference method) on the same day. 3DE image acquisition was performed during a 10-second breath-hold with a frame rate of 100 frames/sec and a rotational speed of 6 rotations/sec. The individual images were postprocessed with Matlab software using multibeat data fusion. Subsequently, with these images, 12 datasets per cardiac cycle were reconstructed, each comprising seven equidistant cross-sectional images for analysis in the new TomTec 4DLV analysis software, which uses a semi-automated border detection (ABD) algorithm. The ABD requires an average analysis time of 15 minutes per patient. A strong correlation was found between LV end-diastolic volume (r = 0.99; y = 0.95x - 1.14 ml; SEE = 6.5 ml), LV end-systolic volume (r = 0.96; y = 0.89x + 7.91 ml; SEE = 7.0 ml), and LV ejection fraction (r = 0.93; y = 0.69x + 13.36; SEE = 2.4%). Inter- and intraobserver agreement for all measurements was good. The fast-rotating transducer with new ABD software is a dedicated tool for rapid and accurate analysis of LV volume and function.

Adult↗

PubMed2005

Ultrafiltration improves aortic compliance in haemodialysis patients.

An elevated pulse pressure leads to an increased pulsatile cardiac load, and results from arterial stiffening. The aim of our study was to test whether a reduction in volume overload by ultrafiltration (UF) during haemodialysis (HD) leads to an improvement of aortic compliance. In 18 patients, aortic compliance was estimated noninvasively before and after HD with UF using a pulse pressure method based on the Windkessel model. This technique has not been applied before in a dialysis population, and combines carotid pulse contour analysis by applanation tonometry with aortic outflow measurements by Doppler echocardiography. The median UF volume was 2450 ml (range 1000-4000 ml). The aortic outflow volume after HD (39 ml; 32-53 ml) was lower (P=0.01) than before (46 ml; 29-60 ml). Carotid pulse pressure after HD (42 mmHg; 25-85 mmHg) was lower (P=0.01) than before (46 mmHg; 35-93 mmHg). Carotid augmentation index after HD (22%; 3-30%) was lower (P=0.001) than before (31%; 7-53%). Carotid-femoral pulse wave velocity was not different after HD (8.7 m/s; 5.6-28.9 m/s vs 7.7 m/s; 4.7-36.8 m/s). Aortic compliance after HD (1.10 ml/mmHg; 0.60-2.43 ml/mmHg) was higher (P=0.02) than before (1.05 ml/mmHg; 0.45-1.69 ml/mmHg). The increase in aortic stiffness in HD patients is partly caused by a reversible reduction of aortic compliance due to volume expansion. Volume withdrawal by HD moves the arterial wall characteristics back to a more favourable position on the nonlinear pressure-volume curve, reflected in a concomitant decrease in arterial pressure and improved aortic compliance.

Adult↗

PubMed2003

Clinical utility and cost effectiveness of a personal ultrasound imager for cardiac evaluation during consultation rounds in patients with suspected cardiac disease.

OBJECTIVE: To assess the clinical utility and cost effectiveness of a personal ultrasound imager (PUI) during consultation rounds for cardiac evaluation of patients with suspected cardiac disease. METHODS: 107 unselected patients from non-cardiac departments (55% men) were enrolled in the study. After the physical examination the consultant cardiologist performed an echocardiographic study with a PUI. The final report was given instantly to the referring physician. All patients subsequently underwent a study with a standard echocardiographic device (SED). For each patient the consultant cardiologist noted whether the findings of the PUI were adequate for final diagnosis. The total cost when full echocardiography was used was compared with the cost when the PUI was used. The time interval from request to diagnosis was also compared. RESULTS: In 84 (78.5%) patients no further examination with an SED was regarded as necessary. Twenty three patients (21.5%) required a further detailed examination with the SED because of the need for haemodynamic information. There was an excellent agreement for the detection of abnormalities between the two devices (96%). The total cost was euro;132 per patient with the SED and euro;75 per patient with the PUI. According to this study, the use of the PUI can lead to a 33.4% reduction of total cost. The mean time from request to diagnosis at the authors' institution was four days for the SED and instantly for the PUI, for additional potential cost savings. CONCLUSIONS: Immediate echocardiographic assessment during consultation rounds can lead to significant cost savings and can shorten the time to diagnosis.

Ambulatory Care↗

PubMed2001

Second harmonic imaging improves sensitivity of dobutamine stress echocardiography for the diagnosis of coronary artery disease.

OBJECTIVE: Our purpose was to assess the value of second harmonic imaging compared with fundamental imaging for the diagnosis of coronary artery disease during dobutamine stress echocardiography. PATIENTS AND METHODS: Sixty-four patients underwent dobutamine stress echocardiography with both fundamental imaging and second harmonic imaging. Coronary angiography was performed within 3 months. Ischemia was defined as new or worsening wall motion abnormalities in > or = 1 segment during dobutamine stress echocardiography. Coronary artery disease was defined as a > or = 70% luminal diameter stenosis in > or = 1 coronary artery by coronary angiography. RESULTS: There was a higher prevalence of segments with invisible border with fundamental compared with second harmonic imaging both at rest (11% vs 8%, P < .05) and at peak stress (17% vs 10%, P < .001). Significant coronary artery disease was present in 49 (77%) patients. The sensitivity of dobutamine stress echocardiography for detection of coronary artery disease by fundamental and second harmonic imaging was, respectively, 78% and 94% (P < .05), whereas specificity was similar (73% vs 73%). Second harmonic imaging had a particularly higher sensitivity for the diagnosis of 1-vessel disease (93% vs 50%, P < .05). CONCLUSION: The use of second harmonic imaging improves the sensitivity of dobutamine stress echocardiography for the diagnosis of coronary artery disease compared with fundamental imaging, particularly for 1-vessel coronary artery disease, whereas specificity remains unchanged.

Chi-Square Distribution↗

PubMed2000

A fast rotating scanning unit for real-time three-dimensional echo data acquisition.

Most three-dimensional (3-D) echocardiography (3-DE) systems today are based on off-line methods where a large number of cross-sectional 2-D scans have to be acquired sequentially before a 3-D image can be reconstructed. Because acquisition is done step-by-step based on ECG triggering plus respiratory gating, this introduces motion artefacts and takes significant acquisition time. Another 3-D approach is based on 2-D transducers and parallel beam-forming. Such a system is very complex. In this manuscript, a fast continuously-rotating scanning unit, based on a 64-element phased-array transducer, is described. Typical rotation speed of the 3-D unit is 8 rotations per s. Therefore, 16 3-D volume datasets can be acquired per s in real-time. The first clinical examples as acquired with this probe are presented.

Artifacts↗

PubMed2000

Automated cardiac output measurements by ultrasound are inaccurate at high cardiac outputs.

OBJECTIVE: The sonographic technique of automated cardiac output measurement (ACM) is a promising new method to measure cardiac output and could be of use in a high-risk obstetric unit in the treatment of pre-eclamptic patients. The aim was to determine the accuracy of the ACM method. DESIGN: Comparative study of the sonographic technique of ACM versus cardiac output measured by thermodilution (TD). METHODS: The study included 39 intensive care patients, 21 men, 13 non-pregnant women and five severely pre-eclamptic pregnant patients, with a wide range of cardiac outputs, in whom TD catheters had been inserted for clinical reasons. Two separate experienced observers, blinded to the results obtained with the other method, performed four successive measurements in each patient with either the ACM or TD technique. The averaged cardiac output value per patient and method was used for comparison. RESULTS: Cardiac output was successfully measured with ACM and TD in 85 and 100% of patients, respectively. Mean cardiac output measured by ACM (6.77 +/- 1.90 L/min) was significantly lower than that measured by TD (9.12 +/- 3.06 L/min). Although cardiac output values obtained with ACM were significantly correlated with those measured by TD, the ACM values were consistently lower than TD values in the higher cardiac output range; the relationship was represented by ACM = 0.35 TD + 3.55 L/min (r = 0.57, P < 0.001). The (ACM - TD) difference increased significantly with cardiac output, through a difference in stroke volume, not in heart rate. CONCLUSION: The ACM is not an accurate tool to measure cardiac output in patients with a high cardiac output, including treated pre-eclamptic women.

Adult↗

PubMed2000

Optimal rotational interval for 3-dimensional echocardiography data acquisition for rapid and accurate measurement of left ventricular function.

BACKGROUND: Prolonged 3-dimensional echocardiography (3DE) acquisition time currently limits its routine use for calculating left ventricular volume (LVV) and ejection fraction (EF). Our goal was to reduce the acquisition time by defining the largest rotational acquisition interval that still allows 3DE reconstruction for accurate and reproducible LVV and EF calculation. METHODS: Twenty-one subjects underwent magnetic resonance imaging and precordial 3DE with 2 degrees acquisition intervals. Images were processed to result in data sets containing images at 2 degrees, 4 degrees, 8 degrees, 16 degrees, 32 degrees, and 64 degrees intervals by excluding images in between. With use of the paraplane feature, 8 equidistant short-axis slices were generated from each data set. The suitability of these short-axis slices for manual endocardial tracing was scored visually by 4 independent experienced observers. The LVV and EF were calculated by using Simpson's rule from 3DE data sets with 2 degrees, 8 degrees, and 16 degrees intervals, and the results were compared with values obtained from magnetic resonance imaging. The probability of 3DE to detect LVV and EF differences was calculated. RESULTS: All patients were in sinus rhythm with a mean heart rate of 72 bpm (SD + or - 12). The LV short-axis images obtained with 16 degrees rotational scanning intervals allowed LV endocardial tracing in all subjects. Good correlation, close limits of agreement, and nonsignificant differences were found between values of LVV and EF calculated with 3DE at 2 degrees, 8 degrees, and 16 degrees rotational intervals and those obtained with magnetic resonance imaging. At steps of 16 degrees, 3DE had excellent correlation (r = 98, 99, and 99), close limits of agreement (+ or - 38, + or - 28.6, and + or - 4.8), and nonsignificant differences (P =.5,.8, and.2) with values obtained from magnetic resonance imaging for calculating end-diastolic LVV, end-systolic LVV, and EF, respectively. Three-dimensional echocardiography with use of 16 degrees rotational intervals could detect 15-mL differences in end-diastolic volume with a probability of 95%, 11-mL differences in end-systolic volume with a probability of 92%, and 0.02 differences in EF with a probability of 95%. CONCLUSIONS: The 3DE data sets reconstructed with images selected at 16 degrees intervals from data sets obtained at 2 degrees precordial rotational acquisition intervals allowed the generation of LV short-axis images with adequate quality for endocardial border tracing. Therefore precordial acquisition at 16 degrees intervals would be sufficient for the reconstruction of 3DE data sets for LV function measurement. This would reduce the acquisition time while maintaining enough accuracy for clinical decision making and would thus make 3DE more practical as a routine method.

Adult↗

PubMed1999

Dobutamine stress echocardiography and technetium-99m-tetrofosmin/fluorine 18-fluorodeoxyglucose single-photon emission computed tomography and influence of resting ejection fraction to assess myocardial viability in patients with severe left ventricular dysfunction and healed myocardial infarction.

The purpose of this study was to compare 2 different techniques--dobutamine-atropine stress echocardiography (DSE) and dual-isotope simultaneous acquisition (technetium-99-m-tetrofosmin/fluorine 18-fluorodeoxyglucose) single-photon emission computed tomography (DISA-SPECT)--for assessment of viable myocardium. One hundred ten patients (mean age 55 +/- 9 years) with left ventricular (LV) dysfunction (mean LV ejection fraction 27 +/- 13%) underwent both DISA-SPECT and DSE. A 16-segment scoring model was adopted for both techniques. Four types of wall motion during DSE were assessed: (1) biphasic, improvement at low dose (10 microg/kg/min) with worsening at high dose; (2) worsening, deterioration without initial improvement; (3) sustained, persistent or late improvement; and (4) no change. Viability criteria were biphasic, worsening, and sustained improvement with DSE. Viability criteria with DISA-SPECT were normal perfusion and metabolism (normal), concordantly mildly reduced perfusion and metabolism (subendocardial scar), or severely reduced perfusion and increased metabolism (mismatch). Myocardium was considered nonviable with DSE in case of unchanged wall motion, or moderate reduction or absence in both technetium-99m-tetrofosmin perfusion and fluorodeoxyglucose uptake with DISA-SPECT. Of 1,756 of 1,760 analyzable LV segments, 1,373 (78%) had severe wall motion abnormalities at baseline (severe hypokinesia, akinesia, or dyskinesia). Of these abnormal segments, 282 (21%) were considered viable during DSE (63 [5%] with biphasic response, 47 [3%] with ischemia, and 172 [13%]) with sustained improvement, whereas 1,091 (79%) were considered nonviable. With DISA-SPECT, 396 (29%) segments were considered viable (312 [23%] with matched perfusion/metabolism and 84 [6%] with mismatch), whereas 977 segments (71%) were considered nonviable. Both techniques showed agreement for viability in 201 segments and 896 were concordantly classified as nonviable. Disagreement was present in 276 segments of which 195 (71%) were nonviable with DSE and viable with DISA-SPECT. Overall agreement between the 2 techniques was 81% (kappa 0.46) in a subgroup of patients with an ejection fraction <25% 78% (kappa 0.39). Thus, DSE and DISA-SPECT show good agreement for assessing viable myocardium not influenced by resting ejection fraction. DSE underestimated the amount of viable tissue compared with DISA-SPECT.

Blood Pressure↗

PubMed1999

Potentials and limitations of the Valsalva maneuver as a method of differentiating between normal and pseudonormal left ventricular filling patterns.

Pseudonormalization of the left ventricular (LV) filling pattern complicates the Doppler echocardiographic assessment of LV diastolic function in patients with heart failure. The Valsalva maneuver is recommended as a method of differentiating between normal and pseudonormal LV filling patterns. However, neither a standardized Valsalva maneuver nor a healthy control population has been studied so far. Therefore, we studied changes in mitral flow velocities in response to a standardized Valsolva maneuver in 55 heart failure patients with LV systolic dysfunction and 35 control subjects. The study subjects were instructed to elevate their intrathoracic airway pressure to 40 mm Hg for 10 seconds. Doppler mitral flow velocities were recorded at rest and during the Valsalva maneuver. All study subjects had comparable decreases in early mitral flow velocity, but mitral flow velocity at atrial contraction increased rather than decreased in patients with a restrictive LV filling pattern. This markedly abnormal response might be useful in detecting elevated filling pressures and pseudonormal filling patterns. Furthermore, in all but 2 patients and all control subjects with an E/A ratio between 1 and 2, inversion of the E/A ratio occurred. This proves that, in contrast to previous beliefs, inversion of the E/A ratio does not differentiate between normal and pseudonormal LV filling patterns.

Blood Flow Velocity↗

PubMed1999

Comparison of native and contrast-enhanced harmonic echocardiography for visualization of left ventricular endocardial border.

Our study was designed to compare the utility of fundamental and second harmonic imaging (SH) for visualization of the left ventricular (LV) endocardial border. SH is a new imaging modality using nonlinear acoustic response, which may provide better endocardial border delineation. Standard apical views were studied in 42 patients using fundamental frequency (FF), SH without contrast (1.6- to 1.8-MHz and 2.1- to 2.5-MHz transmission frequencies), and SH after an intravenous injection of 2.5 g of Levovist. The quality of endocardial delineation in 16 standard segments was scored from 0 to 2. The endocardial visualization index was calculated as a mean of the scores. SH with and without contrast significantly improved LV endocardial border detection (endocardial visualization index 1.25+/-0.53, 1.64+/-0.67, 1.55+/-0.69, and 1.73+/-0.28 for fundamental, lower, and higher frequency harmonic and contrast-harmonic mode, respectively, p <0.005). Improvement was found in all LV segments. The number of invisible segments decreased from 142 (FF) to 54, 112, and 61 (in lower, higher, and contrast SH mode, respectively, p <0.001). Endocardial delineation in the apical segments using SH was optimal after contrast injection. In the basal LV area, contrast-enhanced images were less informative because of signal attenuation. Thus, SH significantly improves visualization of the LV endocardial border. Contrast enhancement with Levovist improves imaging of the apical segments but has no additional advantage in the basal segments. SH emerges as first-line modality for studies of LV function.

Contrast Media↗

PubMed1999

Appropriate 3-dimensional echocardiography data acquisition interval for left ventricular volume quantification: implications for clinical application.

UNLABELLED: Volume-rendered 3-dimensional echocardiography (3DE) acquired with small imaging intervals has been validated for accurate left ventricular (LV) volume measurement. However, its clinical application is often impeded by the lengthy acquisition time. The aim of this study was to examine the accuracy of LV volume measurement from 3DE data acquired at different intervals. METHODS: Transthoracic 3DE LV data sets were acquired at intervals of 2 degrees, 6 degrees, 9 degrees, 12 degrees, 15 degrees, 18 degrees, and 20 degrees in 10 human subjects with various cardiac shapes and function. The LV end-diastolic volume and end-systolic volume were measured from each 3DE data set with the "summation of disks" method. Interobserver and intraobserver variability were also examined. Measurements obtained from data acquired at 2 degrees intervals were used as references for comparison. RESULTS: From 10 subjects a total of 70 3DE data sets were obtained. Data acquisition time decreased from 189 +/- 143 seconds at intervals of 2 degrees to 19 +/- 6 minutes at 20 degrees. No statistically significant difference was found among the measurements derived from data obtained at various intervals. Excellent agreement was obtained between interobserver and intraobserver measurements. CONCLUSION: Data acquired at 12 degrees and 15 degrees intervals remained accurate for LV volume measurement and saved over 80% of time in comparison with data acquired at 2 degrees intervals. A further increase in imaging intervals tended to underestimate LV volumes without significant acceleration of the procedure.

Adult↗

PubMed1998

Measurements and day-to-day variabilities of left ventricular volumes and ejection fraction by three-dimensional echocardiography and comparison with magnetic resonance imaging.

The aim of this study was to assess day-to-day variability of left ventricular (LV) volume and ejection fraction (EF) calculated from 3-dimensional echocardiography (3-DE) and to compare the reproducibility of the measurement with magnetic resonance imaging. Forty-six subjects were examined including 15 normal volunteers (group A) and 31 patients with LV dysfunction (group B). Precordial 3-DE acquisition was performed at 2 degrees rotational intervals and repeated 1 week later. Magnetic resonance imaging was performed at 0.5 T. End-diastolic and end-systolic LV volumes were derived using Simpson's rule by manual endocardial tracing of 8 equidistant parallel LV short-axis slices with 3-DE, whereas 9-mm slices were used with magnetic resonance imaging. The mean +/- SD of end-diastolic and end-systolic LV volumes (ml) and EF (%) from magnetic resonance imaging were 182 +/- 75, 121 +/- 76, and 39 +/- 18, whereas those from 3-DE were 182 +/- 76, 121 +/- 77, and 39 +/- 18 respectively. Day-to-day measurements of end-diastolic and end-systolic LV volumes, and EF on 3-DE were not significantly different as assessed with SEE (2.7, 1.1, and 2.4, respectively). Intra- and interobserver SEE for calculating end-diastolic and end-systolic LV volumes and EF for magnetic resonance imaging were 6.3, 4.7, and 2.1 and 13.6, 11.5, and 4.7, respectively, whereas those for 3-DE were 3.1, 4.4, and 2.2 and 6.2, 3.8, and 3.6, respectively. Day-to-day variability of LV volume and EF calculation on 3-DE were small and not significantly different for normal and dysfunctional left ventricles. Observer variabilities of 3-DE were fewer than those of magnetic resonance imaging. Therefore, 3-DE is recommended for serial assessment of LV volume and EF in normal and abnormally shaped ventricles.

Adult↗

PubMed1998

Usefulness of pulse-wave Doppler tissue sampling and dobutamine stress echocardiography for the diagnosis of right coronary artery narrowing.

To study the feasibility and diagnostic accuracy of right coronary artery (RCA) narrowing by right ventricular (RV) pulse-wave Doppler tissue sampling during dobutamine stress echocardiography (DSE), 30 patients (mean age 55 +/- 9.5 years, 26 men) with suspected coronary artery disease underwent DSE (up to 40 microg/kg/min with additional atropine during submaximum heart rate responses). Pulse-wave Doppler tissue sampling of RV free walls close to the tricuspid annulus was performed in the apical 4-chamber view. The maximum velocity during the ejection phase, early, and late diastole was measured. Data from 5 consecutive beats were averaged. The measurements were repeated at rest, at low dose (10 microg/kg/min), and at peak dobutamine stress. The results were evaluated for the prediction of significant proximal or medium RCA narrowing (> or = 50% diameter stenosis, assessed by quantitative coronary angiography within the previous 3 months). A progressive increase of the ejection phase velocity (> 25% between 10 microg/kg/min and peak stress) was predictive of a normal RCA, whereas a blunted increase and/or decrease (< 25% of increase) was predictive of significant RCA narrowing: sensitivity (95% confidence intervals): 82% (68 to 96), specificity: 78% (67 to 93), positive predictive value: 69% (52 to 86), negative predictive value: 88% (75 to 100), accuracy: 79% (65 to 94). Pulse-wave Doppler tissue sampling provided analyzable data in 100%, whereas the visual assessment of gray-scale images was possible only in 90%. Thus, in patients with suspected RCA narrowing, pulse-wave Doppler tissue sampling during DSE was able to diagnose significant RCA narrowing.

Cardiotonic Agents↗

PubMed1998

Visualization and quantification of myocardial mass at risk using three-dimensional contrast echocardiography.

OBJECTIVE: Three-dimensional echocardiographic assessment of myocardial ischemia using contrast echocardiography has been hampered by limitations of available contrast agents and analytic software. In the study presented, a three-dimensional perfusion imaging method was evaluated in the porcine model of myocardial ischemia using a novel contrast agent. METHODS: Three-dimensional echocardiography was performed in eight open-chested pigs before, during and after left anterior descending (six animals) or circumflex (two animals) coronary artery occlusion. The intramyocardial contrast effect was obtained by left atrial injection of Myomap, a deposit contrast agent. RESULTS: Myocardial opacification was visible in all studies and retained in all three-dimensional datasets. Three-dimensional intensity analysis demonstrated a significant difference, exceeding 20 intensity units in every animal (in 127-level scale), between perfused and non-perfused myocardium. Reperfusion followed by contrast reinjection resulted in homogenous myocardial enhancement. Myocardial mass at risk was clearly delineated in all studies and measured with a mean error of -0.1 +/- 2.0 g against real mass (p = non-significant). Spatial extent of ischemia could be displayed in volume-rendered reconstruction of separate perfusion territories. CONCLUSIONS: Quantitative analysis of myocardial contrast enhancement from three-dimensional datasets is feasible and allows accurate measurement of myocardial mass at risk.

Animals↗

PubMed1998

Improved quantification of myocardial mass by three-dimensional echocardiography using a deposit contrast agent.

The aim of the study was to assess the usefulness of a novel contrast agent in combination with three-dimensional echocardiography for improved mass quantification. Three-dimensional reconstruction of left ventricular myocardium was performed from images obtained with rotational epicardial acquisition in eight open-chested pigs, before and after injection of a deposit contrast agent, Quantison Depot. Three-dimensional echocardiographic myocardial mass values were in excellent agreement with weighted mass (differences -1.6 +/- 5.0 g for end-diastolic frame, -2.8 +/- 4.5 g for end-systolic, 1.0 +/- 1.0 g for end-diastolic with contrast and 0.6 +/- 2.0 g for end-systolic with contrast, p = NS). Left ventricular mass measurements after contrast injection were more accurate and had less measurement variability. In conclusion, myocardial contrast enhancement improves left ventricular mass calculation with three-dimensional echocardiography.

Analysis of Variance↗

PubMed1998

Tissue Doppler imaging and the quantification of myocardial function.

Tissue Doppler imaging (TDI) has recently been introduced in clinical echocardiography. Most widely used are tissue velocity maps, in which the velocity of moving tissue is calculated relative to the transducer from the Doppler shift and displayed as colour-encoded velocity maps in either M-mode or two-dimensional image formats (Doppler velocity mode). This allows detection and quantification of dyssynergic areas of the myocardium. Additionally, the velocities may be studied with pulsed wave-tissue Doppler sampling (PW-TDS) which displays the velocity of a selected myocardial region versus time with high temporal resolution. Less often used, are tissue acceleration maps which display acceleration or velocity change of subsequent frames as different colours (Doppler acceleration mode). These maps may find application in clinical electrophysiology. Another TDI modality is tissue energy imaging, which is based on the integration of the power spectrum of the Doppler signals from the tissue. This technique provides maps of Doppler energy which are represented as colour brightness. Such maps offer potential for the study of myocardial perfusion. TDI modalities have promise to become clinically useful for quantifying myocardial function.

Animals↗

PubMed1997

Accurate assessment of mitral valve area in patients with mitral stenosis by three-dimensional echocardiography.

The accuracy of measurements of mitral valve orifice area (MVA) from three-dimensional echocardiographic (3DE) image data sets obtained by a transthoracic or transesophageal rotational imaging probe was studied in 15 patients with native mitral stenosis. The smallest MVA was identified from a set of eight parallel short-axis cut planes of the mitral valve between the anulus and the tips of leaflets (paraplane echocardiography) and measured by planimetry. In addition, MVA was measured from the two-dimensional short-axis view (2DE). Values of MVA measured by 3DE and 2DE were compared with those calculated from Doppler pressure half-time (PHT) as a gold standard. Observer variabilities were studied for 3DE. MVA measured from PHT ranged between 0.55 and 3.19 cm2 (mean +/- SD 1.57 +/- 0.73 cm2), from 3DE between 0.83 and 3.23 cm2 (mean +/- SD 1.55 +/- 0.67 cm2), and from 2DE between 1.27 and 4.08 cm2 (mean +/- SD 1.9 +/- 0.7 cm2). The variability of intraobserver and interobserver measurements for 3DE measurements was not significantly different (p = 0.79 and p = 0.68, respectively); for interobserver variability, standard error of the estimate = 0.25. There was excellent correlation, close limits of agreement (mean difference +/- 2 SD), and nonsignificant differences between 3DE and PHT for MVA measurements (r = 0.98 [0.02 +/- 0.3] and p = 0.6), respectively. There was moderate correlation, wider limits of agreement, and significant difference between 2DE and PHT for MVA measurements (r = 0.89 [0.32 +/- 0.66] and p = 0.002), respectively. This may be related to the difficulties in visualization of the smallest orifice in precordial short-axis views. This study suggests that three-dimensional image data sets, by providing the possibility of "computer slicing" to generate equidistant parallel cross sections of the mitral valve independently from physically dictated ultrasonic windows, allow accurate and reproducible measurement of the MVA.

Adult↗

PubMed1997

The apical long-axis rather than the two-chamber view should be used in combination with the four-chamber view for accurate assessment of left ventricular volumes and function.

BACKGROUND: Most biplane methods for the echocardiographic calculation of left ventricular volumes assume orthogonality between paired views from the apical window. Our aim was to study the accuracy of biplane left ventricular volume calculations when either the apical two-chamber or long-axis views are combined with the four-chamber view. The left ventricular volumes calculated from three-dimensional echocardiographic data sets were used as a reference. Twenty-seven patients underwent precordial three-dimensional echocardiography using rotational acquisition of planes at 2-degree intervals, with ECG and respiratory gating. End-diastolic and end-systolic left ventricular volumes and ejection fraction on three-dimensional echocardiography were calculated by (1) Simpson's methods (3DS) at 3 mm short-axis slice thickness (reference method) and by (2) biplane ellipse from paired views using either apical four- and two-chamber views (BE-A) or apical four- and long-axis views (BE-B). Observer variabilities were studied by the standard error of the estimate % (SEE) in 19 patients for all methods. RESULTS: The spatial angles (mean +/- SD) between the apical two-chamber, long-axis and four-chamber views were 63.3 degrees +/- 19.7 and 99.1 degrees +/- 25.6, respectively. The mean +/- SD of end-diastolic and end-systolic left ventricular volumes (ml) and ejection fraction (%) by 3DS were 142.2 +/- 60.9, 91.8 +/- 59.6 and 39.6 +/- 17.5, while that by BE-A were 126.7 +/- 60.4, 84.0 +/- 57.9 and 39 +/- 17 and by BE-B were 134.3 +/- 62.4, 88.6 +/- 59.7 and 39.1 +/- 16.7, respectively. BE-B intra-observer (8.4, 6.7 and 3.5) and inter-observer (9.8, 11.5 and 5.4) SEE for end-diastolic and end-systolic left ventricular volumes (ml) and ejection fraction (%), respectively, were smaller than that for BE-A (10.8, 8.8 and 4.1 and 11.4, 14.7 and 6.1, respectively). There was excellent correlation between 3DS and BE-A (r = 0.99, 0.98 and 0.98) and BE-B (0.98, 0.98 and 0.98) for calculating end-diastolic and end-systolic left ventricular volume and ejection fractions, respectively. There were no significant differences between BE-A and BE-B with 3DS for end-diastolic and end-systolic left ventricular volume and ejection fraction calculations (P = 0.2, 0.3 and 0.4 and P = 0.5, 0.5 and 0.4, respectively). There were closer limits of agreement (mean +/- 2 SD) between 3DS and BE-B 7.9 +/- 18.8, 3.2 +/- 14.2 and 0.8 +/- 5.8 than that between 3DS and BE-A 15.5 +/- 19.6, 7.8 +/- 16.2 and 1.1 +/- 7.4 for calculating end-diastolic and end-systolic left ventricular volume and ejection fractions, respectively. CONCLUSION: Both apical two-chamber and apical long-axis views are not orthogonal to the apical four-chamber view. Observer variabilities of BE-B were smaller than that for BE-A. BE-A and BE-B have excellent correlation and non-significant differences with 3DS for left ventricular volume and ejection fraction calculations. There were closer limits of agreement between BE-B with 3DS for left ventricular volume and ejection fraction calculations than that between BE-A and 3DS. Therefore, we recommend the use of the apical long-axis rather than the two-chamber view in combination with the four-chamber view for accurate biplane left ventricular volume and ejection fraction calculations.

Adult↗