Three-Dimensional Echocardiography: Precision and Accuracy of Left Ventricular Volume Measurement Using Rotational Geometry with Variable Numbers of Slice Resolution

We developed a new, rapid (6 seconds) acquisition technique allowing collection of approximately six through nine apical rotational tomograms for three-dimensional (3-D) echocardiography. To justify an appropriate sampling density for precise and accurate measurement of chamber volumes in left ventricles with complicated shape, we designed a validation study in vitro using six canine heart specimens with irregular, asymmetric left ventricles with known volumes (28.5 to 104.3 ml; mean, 71.2 ml). The number of equally spaced slices were incrementally deleted from the original high resolution scans (48 slices) to 2 slices in 3-D reconstruction. We created subgroups of 48- and 36-, 24- and 16-, 12- and 8-, 6- and 4-, and 3- and 2-component slices to compare left ventricular (LV) volumes measured in 3-D images with different slice resolution with the reference standard measured in the specimen. The accuracy and precision of LV volume were relatively constant in the subgroup of 4- and 6- through 36- and 48-component slices. When the subgroup with 6- and 4-component slices was used, the correlation was r = 0.991, P < 0.0001, root mean-square percent error of 5.0%, bias of 0.5 ± 3.7 ml, and interobserver variability of 5.0%. With the reduction in component slices equal or less than three, the accuracy decreased significantly (root-mean-square percent error = 8.1% and bias = -2.0 ± 5.7 ml) compared with higher slice resolutions. This study demonstrated that 3-D echocardiography using apical rotational techniques can accurately quantify LV volume in the canine heart specimens with irregular shapes with as few as 4–6 axial slices. The rapid 3-D acquisition technique is therefore anticipated to yield precise and accurate LV volumetry.     

In Vitro Feasibility and Accuracy of Three-Dimensional Echocardiography for Ventricular Volume Assessment in Very Small Hearts

To evaluate the in vitro accuracy of three-dimensional echocardiography (3-DE) for estimation of ventricular volume in very small hearts, left ventricular (LV) volume was determined by 3-DE in the excised hearts of 10 guinea pigs and 10 rabbits, and right ventricular (RV) volume was determined in 20 rabbits. The effect of edge enhancement, Sigma filter, and slice distance (1 mm versus 0.5 mm) was assessed in each heart. True volumes were obtained from ventricular casts. Mean cast volume was 1.38 ± 0.83 mL for LVs and 1.63 ± 1.01 mL for RVs. Correlations between 3-DE and true volumes were r > 0.99 (P < 0.0001) for both ventricles. Accuracy was not affected by ventricular type, slice distance, or Sigma filter. Mean percent difference from true volume was significantly less (P = 0.03) with edge enhancement. Ventricular volume can be assessed reliably by 3-DE in very small hearts. The edge enhancement feature improved the accuracy of the measurements.     

Three-Dimensional Echocardiography in Evaluation of Left Ventricular Indices

Accurate determination of left ventricular mass, volume, ejection fraction, and wall motion is important for clinical decision making. Currently, M-mode and two-dimensional echocardiography (2DE) have been routinely used for this purpose. Although these 1D or 2D modalities provide excellent diagnostic and prognostic information, they have a number of technical limitations including the time required to perform the procedure and operator-dependent image acquisitions. In addition, they are inherently limited by geometric assumption of three-dimensional (3D) left ventricular structures based on 2D slices. With the improvement in transducer technology and software development, 3D echocardiography (3DE) has become widely available. Left ventricular quantitation by 3DE has been demonstrated to be accurate by multiple studies that compared 3DE with reference techniques. In addition, 3DE measurements were found to be more reproducible and less variable than 2DE. Real time 3DE imaging has potential advantages in stress echocardiography including rapid acquisition, unlimited number of planes, avoidance of foreshortening, and precise segment matching. This is a major step forward in our diagnostic armamentarium for the evaluation of ischemia. In this review, we summarized the current evidence of 3DE for left ventricular evaluation. (Echocardiography 2012;29:66-75)     

2D and 3D Echocardiography of a Left Ventricular Diverticulum

A real time transthoracic 3D study of a left ventricular diverticulum established through a narrow orifice located between the aortic and mitral valves is presented. Diverticular morphology was reconstructed and its volumes were calculated by this technique for the first time in the literature.     

Left Ventricular Outflow Tract Obstruction in the Transposition of Great Arteries Defined by Transthoracic Three-Dimensional Echocardiography

We assessed the feasibility of transthoracic three-dimensional reconstruction of the pulmonary valve and subpulmonary left ventricular outflow tract in two patients with transposition of great arteries, ventricular septal defect, and obstruction to the left ventricular outflow tract. Three-dimensional reconstruction of the pulmonary valve could be displayed as "en face" through a three-dimensional generated "pulmotomy view," allowing an overview of the pulmonary aspect of the valve from a surgeon's perspective. In similar fashion, reconstruction of the subpulmonary outflow tract could be displayed along its longitudinal axis as seen through a left ventriculotomy. Unique views could be obtained equivalent to surgical or autopsy dissections, allowing more complete understanding of the morphology and severity of left-sided obstructive lesions.     

Direct Measurement of Left Ventricular Outflow Tract Area Using Three‐Dimensional Echocardiography in Biplane Mode Improves Accuracy of Stroke Volume Assessment

Aims: The aim of the study was to investigate whether left ventricular stroke volume (LVSV) assessment using direct measurement of left ventricular outflow tract area (LVOT_A) is superior to conventional methods for SV calculation. Methods and results: Thirty patients were included in the study (39 ± 12 years). LVSV was assessed by multiplying LVOT velocity time integral (VTI) by LVOT_A provided by direct planimetrical measurements from real time three‐dimensional echocardiography (RT3DE) in biplane mode (SV₂). These measurements were compared to conventional methods using either the LVOT diameter for LVOT_A multiplied with VTI (SV₁) or biplane Simpson (SV₃). Direct SV measurements by RT3DE were used as gold standard (SV_ref). There was an excellent correlation and agreement between SV determined by SV₂ and 3DE (r = 0.98, mean difference 0.5 ± 3.3 mL). However, the concordance of the traditional methods (SV₁ and SV₃) with 3DE was weaker (r = 0.38, mean difference ?2.0 ± 17.6 mL, r = 0.84, mean difference ?7.6 ± 8.7 mL, respectively). Furthermore, cardiac output (CO) measurements performed by the different modalities were not concordant with wide limits of agreement, except by SV₂ the mean difference of CO by SV₁ was ?0.12 ± 1.05 L/min, 0.03 ± 0.20 L/min by SV₂, and ?0.45 ± 0.52 L/min by SV₃. Conclusions: SV and CO calculations using direct measurement of LVOT area is a feasible, accurate and reproducible method and correlates extremely well with 3DE volume measurements. SV and CO calculation by LVOT_A is therefore an appealing method for LVSV assessment in clinical routine. (Echocardiography 2010;27:1078‐1085)     

实时三维超声心动图与磁共振成像对比评价室壁瘤患者左心室容积和功能的可行性和准确性

目的:评价实时三维超声心动图(实时三维超声,RT-3DE)测量冠心病合并左心室室壁瘤患者左心室容积和功能的可行性和准确性.方法:根据室壁瘤大小分组,分别应用二维超声心动图(二维超声,2DE)、实时三维超声及磁共振成像(MRI)测量左心室室壁瘤患者手术前、后左心室舒张末容积(LVEDV)、左心室收缩末容积(LVESV)、左心室射血分数(LVEF),以MRI结果为标准,进行对比研究.结果:①术前、术后二维超声和实时三维超声所测各值与MRI所测各值之间小室壁瘤组、中室壁瘤组差异均无统计学意义(P均＞0.05).②大室壁瘤组术前二维超声所测LVEDV、LVESV与MRI所测值之间差异均有统计学意义(P均＜0.05),术前二维超声所测LVEF值与术后各值与MRI所测各值差异无统计学意义,术前、术后三维超声各值与MRI所测各值差异亦无统计学意义(P均＞0.05).③巨大室壁瘤组术前二维及三维超声所测LVEDV、LVESV较MRI所测值低,而LVEF较MRI所测值高,差异均有统计学意义(P均＜0.05).术后二维超声所测LVEDV、LVESV仍较MRI低,差异有统计学意义(P均＜0.05).术后实时三维超声所测各值与MRI所测各值之间差异无统计学意义(P均＞0.05).结论:与二维超声相比,实时三维超声测定大室壁瘤及巨大室壁瘤患者左心室容积与功能更接近MRI测量值,更准确可靠,但对于巨大室壁瘤患者所测术前左心室容积与MRI相比仍有低估.     

Measurement of Left Ventricular Ejection Fraction by Real Time 3D Echocardiography in Patients with Severe Systolic Dysfunction: Comparison with Radionuclide Angiography

Aim: Measurement of left ventricular ejection fraction (LVEF) using real time 3D echocardiography (3DE) has been performed in subjects with preserved or modestly reduced systolic function. Our aim was to evaluate this technique in the subset of patients with severe systolic dysfunction. Methods and results: Consecutive patients with LVEF less than 0.35 at two-dimensional echocardiography were included. LVEF obtained by 3DE was compared to the value measured by radionuclide angiography (RNA). Real time full-volume 3DE was performed, with offline semiautomated measurement of LVEF using dedicated software (Cardioview RT, Tomtec) by a single observer blinded to the results of RNA. A total of 50 patients were evaluated, of whom 38 (76%, 27 males, age 69 ± 13 years) had a 3DE of sufficient quality for analysis. LVEF for this group was 0.21 ± 0.07 using 3DE and 0.27 ± 0.08 using RNA. The agreement between the two techniques was rather poor (r = 0.49; P < 0.001; 95% limits of agreements of −0.20 to 0.09). Truncation of the apex was observed in 6 of 38 (16%) patients. Conclusion: In patients with severe systolic dysfunction, 3DE shows poor agreement for measurement of LVEF as compared to RNA. There may be underestimation of up to 20% in absolute terms by 3DE. Accordingly, the two methods are not interchangeable for the follow-up of LV function. A limitation of 3DE may, at least in part, be related to the incomplete incorporation of the apical region into the pyramidal image sector in patients with dilated hearts. (Echocardiography 2010;27:58-63)     

超声心动图评价左心室功能的研究进展

左室功能的准确测定对临床诊断和治疗有着重要意义,超声心动图是目前最常用于测量左室功能的工具,其具有无创、廉价、重复性好等优点,更为重要的是它不仅可用于评价左室整体收缩功能,还能更加完善地评价左室舒张功能和局部心肌运动,现对近年来超声心动图评价上述心功能的主要方法进行回顾。     

超声心动图与左室辅助装置：现状、问题及未来

作为终末期心脏病的一种目的性治疗或心脏移植的过渡,左室辅助装置的临床应用在逐渐增多,其治疗终点的评价及并发症的诊断正在成为心血管医学界关注的重要问题。超声心动图在左室辅助装置评价中具有重要价值,可用于术前除外禁忌证、术中监测管道的位置并评价左室充盈和减负荷状态、术后监测低血容量、心包填塞及右心衰竭,并用以评价心肌恢复情况。     

Evaluation of Hemodynamic Determinants of Quantitative Tissue Doppler Echocardiography in the Assessment of Left Ventricular Function

The aim of the present study was to determine whether quantitative tissue Doppler echocardiography has a role in the assessment of left ventricular hemodynamics. Thirty patients with suspected or known heart disease, but no wall motion abnormalities, took part in the study. Quantitative tissue Doppler echocardiography was performed using new software for digital analysis of the tissue Doppler signal. Average systolic subendocardial (S1), subepicardial (S2), and transmural (S3) wall velocity data were obtained from the inferoposterior wall and compared with the hemodynamics, including high fidelity pressure readings. S1 and S3 rates were found to be most reliable, being directly related to the peak rate of left ventricular pressure rise (dP/dt_peak) and inversely to systemic vascular resistance (SVR) and resistance index (SVRI). The best correlation was between S1, dP/dt_peak, and SVRI (multiple regression analysis: r = 0.76, P < 0.0001; simple regression analysis relating S1 to dP/dt_peak/SVRI: r = 0.77, SEE = 0.25, P < 0.0001). Thus, wall velocity indices as defined in this study have promise to become helpful in guiding the therapeutic modulation of inotropy and afterload in patients with heart failure.     

Three-Dimensional Echocardiographic Reconstruction of the Left Ventricle by a Transesophageal Tomographic Technique

Accurate determination of left ventricular (LV) volume has important therapeutic and prognostic implications in patients with cardiac disease. Volume estimations by two-dimensional techniques are not very accurate due to geometric assumptions. Objectives: To validate LV volume determinations by a new transesophageal three-dimensional echocardiographic technique. We performed three-dimensional reconstruction of the LV using an echo-computed tomographic (CT) technique based on serial pullback parallel slice imaging technique in both in vitro and in vivo settings. Fourteen latex-balloons with various sizes (30–235 mL) and shapes (conical, pear shaped, round, elliptical, and aneurysms in various locations) filled with known volumes of water were imaged in a water bath. From the static three-dimensional image, the LV long axis was defined and the LV was sectioned perpendicular to this axis into 2-mm slices. The volume of each slice was calculated with the observer blinded to the actual volume as the product of the slice thickness and the manually traced perimeter of the slice and the LV volume as the sum of the volumes of the slices (Simpson's method). The calculated LV volume closely correlated with the actual volume (r = 0.99, P < 0.0001, calculated volume = 1.06x – 11.3, Δvolume =-5.7 ± 10.0 cc). Using the same system, transesophageal echocardiographic (TEE) images of the LV were obtained in 15 patients gated to respiration and ECG. Satisfactory dynamic three-dimensional reconstruction of the LV was possible in ten patients. The three-dimensional LV volumes (systolic and diastolic) using Simpson's method correlated well with those obtained from biplane or multiplane TEE images using the area length method (r = 0.89, P < 0.0001, y = 12.7 + 0.84x, Δvolume = 1.3 ± 18.1 cc). The LV major-axis diameters by the two methods showed very close correlations as well (r = 0.86, P < 0.0001, y = 19 + 0.74x, Δdiameter = 1.0 ± 7.2 mm). We conclude that three-dimensional LV volume calculation by the echo-CT technique is intrinsically sound, is independent of LV geometry, and with some limitations, is applicable in vivo.     

Fast Data Acquisition and Analysis with Real Time Triplane Echocardiography for the Assessment of Left Ventricular Size and Function: A Validation Study

Aims: To assess accuracy and reproducibility of real time simultaneous triplane echocardiography (RT3PE) for the assessment of left ventricular (LV) volumes and ejection fraction (EF) using cardiac magnetic resonance (CMR) as a reference method. Methods and Results: A total of 24 patients with various degrees of LV dysfunction (EF from 36 to 57%) in sinus rhythm with good image quality were enrolled in the study. Digital loops of apical views were recorded with standard two-dimensional imaging and with RT3PE. Echocardiography and CMR were performed within 1 hour. RT3PE measurements of LV end-diastolic volume, end-systolic volume, and EF resulted closely correlated to CMR (r = 0.95, 0.97, and 0.95, respectively) with small biases (−4 ml, −6 ml, and 1%, respectively) and narrow limits of agreement (SD = 15 ml, 12 ml, and 6%, respectively). Two-dimensional echocardiography ( 2DE) showed a weaker correlation with CMR (r = 0.85, 0.91, and 0.83, respectively; P < 0.06) with similar biases (−4 ml, −10 ml, 5%, respectively), but wider limits of agreement (SD = 28 ml, 21 ml, 10%, respectively, P < 0.007). RT3PE showed lower interobserver variability for the assessment of EF (SD = 2% vs. 5%, P = 0.03) and lower measurement time of LV EF (175 ± 54 sec vs. 241 ± 49 sec, respectively; P < 0.0001), as compared to 2DE. Conclusion: RT3PE allows simple and fast image acquisition and volume calculation. In addition, it allows more accurate and reproducible EF measurements than conventional 2DE.     

Left Ventricular Apical Thin Point Viewed with Two-Dimensional Echocardiography

The aim of this study was to evaluate the usefulness of two-dimensional echocardiography in observing the left ventricular apical thin point (LVATP) and to view the change in thickness and width of the LVATP during the cardiac cycle. Transthoracic echocardiography was performed in 32 healthy adult volunteers to observe the LVATP in an apical three-chamber view. The width and thickness of the LVATP were measured at the end-diastole as well as at the end-systole. With two-dimensional echocardiography, the LVATP could be clearly shown. The width of the LVATP at the end-diastole and end-systole was 3.3 mm ± 1.4 mm versus 0.9 mm ± 0.4 mm, P < 0.001; the thickness of the LVATP at the end-diastole and end-systole was 1.7 mm ± 0.6 mm versus 1.8 mm ± 0.8 mm, P > 0.05. The LVATP can be viewed with two-dimensional echocardiography; the LVATP changes significantly in width during the cardiac cycle, whereas the thickness of the LVATP changes insignificantly.     

实时三维超声参数在评价稳定性冠心病患者左心室舒张功能中的作用

目的探讨实时三维超声心动图（real—timethree—dimensional echocardiography,RT-3DE）技术在稳定性冠心病患者左心室舒张功能评价中的应用价值。方法将65例稳定性冠心病患者根据造影检查所示冠状动脉狭窄程度分组。应用RT-3DE技术获取患者左心室容积-时间曲线（volume—timecurve,VTC）,观察整体及各节段VTC形态,计算舒张早期峰值充盈率（peak filling rate,PFR）、平均充盈率（meanfillingrate,MFR）、1,3充盈分数（I／3 filling fraction,1／3 FF）等参数,比较组间差异,选择有效参数进行相关性分析,并计算ROC曲线下面积。结果RT-3DE所测左心室容积、射血分数、峰值射血率（peak ejection rate,PER）及MFR在各组患者中无明显差异。PFR、1／3 FF随着冠状动脉狭窄程度的加重逐渐降低．冠状动脉明显狭窄者与造影结果正常者相比较,差异具有统计学意义（P均〈0．05）。PFR、1／3 FF与E／E’比值及NT—proBNP浓度均呈负相关,1/3 FF相关性优于PFR（与E／E’比值,r=-0．751．P〈0．01;与NT—proBNP浓度,r=0．612,P〈0．01）。以1/3FF判断无显著冠状动脉狭窄（即狭窄程度〈70％）的曲线下面积为0．772（P=0．001）．95％置信区间为0．633—0．911。1/3 FF≥36．75％判断冠状动脉狭窄程度〈70％的敏感性为73％,特异性为76％。氨基末端脑钠肽前体（N—terminal pro—B—type natriuretic peptide,NT—proBNP）。结论RT-3DE可定性、定量反映稳定性冠心病患者左心室舒张功能的变化,1／3FF可在一定程度上检测此类患者初期出现的以舒张早期心肌弛缓异常为主的轻度舒张功能受损。     

Multivariate Analysis of Left Ventricular Mass Determinants in Adults

Echocardiographic left ventricular mass (LVM) estimates are strong predictors of subsequent mortality and cardiovascular events. It is known that blood pressure (BP), weight (WT), and age are significantly correlated with LVM. We hypothesized that stroke volume (SV) measured by Doppler echocardiography would also be correlated with LVM. Two hundred and thirteen patients referred for routine echocardiography had determination of LVM, cuff BP, and Doppler SV. Those with localized LV disease, valvular disease, or cor pulmonale were excluded. In both men and women, systolic BP (SBP) was more closely correlated with LVM than was diastolic blood pressure or mean arterial pressure, and SV was more closely correlated with LVM than cardiac output or cardiac index. Stepwise regression, followed by multiple regression showed that four variables (WT, SV, SBP, and AGE) explained 32.3% of the variability in LVM in men and 48.5% of the variability in LVM in women. WT and SV were significant determinants of LVM in both men and women. Age was also significant in men and SBP was also significant in women. For both men and women, SV was more significantly correlated with LVM than was SBP. The changes in LVM associated with 1 SD increments of SV and SBP, respectively, were 8 and 5 g for men and 13 and 11 g for women. We conclude that men and women have different patterns of variables influencing LVM. Doppler echocardiographic SV is a newly described determinant of LVM that has a greater correlation with LVM than does SBP. This study reemphasizes the importance of WT as the major determinant of LVM.     

Assessment of Left Ventricular Systolic Function Using Color-Coded Tissue Doppler Echocardiography

Tissue Doppler echocardiography can be used to measure myocardial velocity data by using the Doppler shift data of ultrasound waves. Two methods have recently been described to calculate velocity data: pulsed tissue Doppler and color-coded tissue Doppler. This article focuses on color-coded tissue Doppler data to evaluate left ventricular systolic function. Technical considerations and validation studies are reviewed. Potential clinical applications of color-coded tissue Doppler are presented, including dobutamine stress echocardiography, assessment of left ventricular ejection dynamics using mitral annular velocity, and tissue Doppler assessment of cardiac transplant rejection.     

Left Ventricular Mass Estimation by Echocardiography

Echocardiographic determination of left ventricular mass provides prognostic information that is independent of blood pressure. This prognostic information has a graded and continuous relationship with outcome, and is independent of traditional risk factors. This article addresses the prognostic and clinical utility of echocardiography for detection of left ventricular mass. Recommendations will be offered regarding the use of echocardiography for screening in select individuals.