Rapid online quantification of left ventricular volume from real-time three-dimensional echocardiographic data

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.

Assessment of left ventricular size and function during cardiac surgery. An intraoperative evaluation of six two-dimensional echocardiographic methods with real time three-dimensional echocardiography as a reference

Transesophageal echocardiography is recommended to monitor left ventricular (LV) size and function in various operations. Generally, two-dimensional (2D) methods are applied intraoperatively. The aim of this study was to compare the accuracy and feasibility of 6 commonly used 2D methods to assess LV function during surgery. LV function in 120 consecutive patients was evaluated. Real time three-dimensional transesophageal echocardiograpy (3DTEE) served as reference. End-diastolic and end-systolic volumes and ejection fraction (EF) were analyzed with Simpson's method of discs (monoplane [MP] and biplane [BP]), eyeball method, Teichholz' method, and speckle tracking (ST) methods. Furthermore, fractional area change (FAC) and peak systolic pressure rise (dP/dt) were determined. Each 2D method was evaluated regarding correlation and agreement with 3DE, intra- and interobserver variability and the time required for evaluation. Simpson BP showed the strongest correlation and best agreement with 3DE for EF (limits of agreement 3.7 ± 11.6%) and volumes. Simpson MP showed similar agreement with 3DE compared to ST (2.8 ± 14.5% vs. 2.0 ± 15.3% and 3.8 ± 14.4% vs. 1.9 ± 15.6%, respectively). Both the eyeball method and Teichholz' method showed wide limits of agreement (-1.5 ± 18.2% and 5.2 ± 22.1%, respectively). DP/dt did not correlate with 3DE. FAC and ST FAC showed similar agreement. Application of 3DE (429 ± 108 seconds) took the longest time, and the eyeball method took the shortest time (8 ± 5 seconds) for analysis. Simpson BP is the most accurate intraoperative 2D method to evaluate LV function, followed by long-axis MP evaluations. Short-axis views were less accurate but may be suited for monitoring. We do not recommend using dP/dt.

Feasibility of Real-Time Three-Dimensional Echocardiography for the Assessment of Distorted Biventricular Systolic Function in Patients with Cor Pulmonale

Background

This study was to investigate the feasibility of real-time 3-dimensional echocardiography (RT3DE) for the analysis of biventricular ejection fractions and volume measurements in patients with cor pulmonale and the correlations of RT3DE results with 64-slice multi-detector cardiac computed tomography (64-MDCT) results.

Methods

This study included a total of 22 patients (59.3 ± 16.6 years of age; 10 males and 12 females) who showed flattening or reverse curvature of the interventricular septum and severe pulmonary hypertension [mean right ventricular (RV) systolic pressure = 66.8 ± 19.7 mmHg] on 2-dimensional transthoracic echocardiography due to cor pulmonale. Biventricular end-diastolic and end-systolic volumes were measured by RT3DE and 64-MDCT. The severity of D-shaped deformation was evaluated by using left ventricular (LV) eccentricity index (ratio of diameters parallel/perpendicular to the interventricular septum on parasternal short axis images of the papillary muscle level).

Results

There were moderate correlations between biventricular volumes measured by RT3DE and 64-MDCT except for LV end-systolic volume (59.8 ± 17.1 vs. 73.2 ± 20.2 mL, r = 0.652, p = 0.001 for LV end-diastolic volume; 30.6 ± 9.1 vs. 30.8 ± 12.5 mL, r = 0.361, p = 0.099 for LV end-systolic volume; 110.1 ± 42.9 vs. 171.1 ± 55.3 mL, r = 0.545, p = 0.009 for RV end-diastolic volume; and 80.9 ± 35.0 vs. 128.7 ± 45.1 mL, r = 0.549, p = 0.005 for RV end-systolic volume respectively).

Conclusion

This study suggests that RT3DE may be a modest method for measuring distorted biventricular end-systolic and end-diastolic volumes in patients with cor pulmonale.

Midwall ejection fraction for assessing systolic performance of the hypertrophic left ventricle

BACKGROUND

In patients with left ventricular hypertrophy (LVH), LV midwall fractional shortening (FS) is used as a measure of LV systolic performance that is more physiologically appropriate than conventional FS. For evaluation of LV volume and ejection fraction (EF), 2-dimensional (2D) echocardiography is more accurate than M-mode echocardiography. The purpose of this study was to assess systolic performance by midwall EF using 2D speckle tracking echocardiography (STE).

METHODS

Sixty patients were enrolled in the study. Patients were divided into two groups with LVH (n = 30) and without LVH (control group, n = 30). LV systolic function was compared between the two groups and the relationships of left ventricular mass index (LVMI) with LV systolic parameters, including midwall EF, were investigated.

RESULTS

Midwall EF in the LVH group was significantly lower than that in the control group (42.8±4.4% vs. 48.1±4.1%, p <0.0001). Midwall FS was also significantly lower in the LVH group (13.4±2.8% vs. 16.1±1.5%, p <0.0001), but EF did not differ significantly between the two groups. There were significant correlations between midwall EF and LVMI (r=0.731, p <0.0001) and between midwall FS and LVMI (r=0.693, p <0.0001), with midwall EF having the higher correlation.

CONCLUSIONS

These results show that midwall EF can be determined using 2D STE. Midwall EF can be used to monitor LV systolic dysfunction, which is not possible with conventional EF. Evaluation of midwall EF may allow assessment of new parameters of LV systolic function in patients with LV geometric variability.

Advanced echocardiographic techniques

Echocardiography has advanced significantly since its first clinical use. The move towards more accurate imaging and quantification has driven this advancement. In this review, we will briefly focus on three distinct but important recent advances, three‐dimensional (3D) echocardiography, contrast echocardiography and myocardial tissue imaging. The basic principles of these techniques will be discussed as well as current and future clinical applications.

Quantification of left ventricular size and function using contrast-enhanced real-time 3D imaging with power modulation: comparison with cardiac MRI

In patients with optimal images, real-time 3-D echocardiography (RT3DE) allows accurate evaluation of left ventricular (LV) volumes and ejection fraction (EF). However, in patients with poor acoustic windows, lower correlations were reported despite the use of contrast. We hypothesized that power modulation (PM) RT3DE imaging that uses low mechanical indices and provides uniform LV opacification could overcome this problem. Accordingly, we sought to: (i) Test the feasibility of quantification of LV volumes and EF from contrast-enhanced (CE) PM RT3DE images, (ii) validate this technique against cardiac magnetic resonance (CMR) reference and (iii) test its clinical value by quantifying the improvement in accuracy and reproducibility. We studied 20 patients who underwent CMR, harmonic nonenhanced RT3DE and CE PM RT3DE imaging on the same day. All images were analyzed to obtain end-systolic and end-diastolic LV volumes (EDV, ESV) and calculate EF. To determine the reproducibility of each RT3DE technique, imaging was repeated in the same setting by a second sonographer. In addition, patients were divided according to the quality of their RT3DE images into two groups, for which agreement with CMR and reproducibility were calculated separately. CE PM RT3DE imaging improved the accuracy of EDV, ESV and EF measurements in patients with poor acoustic windows without significantly affecting those in patients with optimal images. In addition, CE PM RT3DE imaging improved the reproducibility of the measurements, as reflected by a twofold decrease in intermeasurement variability. Importantly, the variability in CE PM RT3DE-derived volumes and EF was under 10%, irrespective of image quality. This methodology may become the new standard for LV size and function, which will be particularly important in patients with poor acoustic windows or contraindications to CMR.

Early detection of chemotherapy-related left ventricular dysfunction

Modern advances in cancer treatment have resulted in improved survival. As a result, effects of cancer therapy on other organ systems such as the heart are more likely to become clinically relevant. One such possibility is chemotherapy-related left ventricular dysfunction. Although in clinical practice cardiotoxicity is evaluated by symptoms and left ventricular ejection fraction, these occur relatively late in the disease process after the heart's compensatory mechanisms have been expended. Ideally, left ventricular dysfunction would be identified early so that cancer patients and their physicians can make informed decisions about their therapeutic options and institute careful surveillance and early initiation of cardioprotective medication where appropriate. This review discusses the role of echocardiography to detect subclinical left ventricular dysfunction in cancer patients exposed to chemotherapy with potential cardiotoxicity, particularly anthracyclines and trastuzumab.

Performance of 3-dimensional echocardiography in measuring left ventricular volumes and ejection fraction: a systematic review and meta-analysis

OBJECTIVES

The primary aim of this systematic review is to objectively evaluate the test performance characteristics of three-dimensional echocardiography (3DE) in measuring left ventricular (LV) volumes and ejection fraction (EF).

BACKGROUND

Despite its growing use in clinical laboratories, the accuracy of 3DE has not been studied on a large scale. It is unclear if this technology offers an advantage over traditional two-dimensional (2D) methods.

METHODS

We searched for studies that compared LV volumes and EF measured by 3DE and cardiac magnetic resonance (CMR) imaging. A subset of those also compared standard 2D methods with CMR. We used meta-analyses to determine the overall bias and limits of agreement of LV end-diastolic volume (EDV), end-systolic volume (ESV), and EF measured by 3DE and 2D echocardiography (2DE).

RESULTS

Twenty-three studies (1,638 echocardiograms) were included. The pooled biases ± 2 SDs for 3DE were -19.1 ± 34.2 ml, -10.1 ± 29.7 ml, and - 0.6 ± 11.8% for EDV, ESV, and EF, respectively. Nine studies also included data from 2DE, where the pooled biases were -48.2 ± 55.9 ml, -27.7 ± 45.7 ml, and 0.1 ± 13.9% for EDV, ESV, and EF, respectively. In this subset, the difference in bias between 3DE and 2D volumes was statistically significant (p = 0.01 for both EDV and ESV). The difference in variance was statistically significant (p < 0.001) for all 3 measurements.

CONCLUSIONS

Three-dimensional echocardiography underestimates volumes and has wide limits of agreement, but compared with traditional 2D methods in these carefully performed studies, 3DE is more accurate for volumes and more precise in all 3 measurements.

Assessing the Cardiac Toxicity of Chemotherapeutic Agents: Role of Echocardiography

Advancements in cancer treatment have resulted in sufficient survival length for patients to experience treatment-related cardiac complications. In particular, chemotherapy-induced cardiac dysfunction significantly impacts morbidity and mortality rates in cancer patients. The presence of cardiotoxicity from chemotherapy has been traditionally assessed using clinical symptoms and decreases in left ventricular ejection fraction (LVEF). However, in this indication, LVEF lacks accuracy as a measure of subclinical cardiotoxicity and its prognostic value is controversial. There is an emphasis to identify subclinical and left ventricular dysfunction early, in order to allow cancer patients and their physicians to make informed decisions about therapeutic options. Echocardiography is a readily available noninvasive tool to measure cardiac function and plays a major role in the diagnosis of cardiotoxicity. This review focuses on the role of echocardiography in detecting cardiotoxicity, and will discuss conventional and more recent echocardiographic approaches for assessing subclinical cardiotoxicity.

Agreement between cardiac outputs by four-dimensional echocardiography and thermodilution method is poor

OBJECTIVE

The objective of the study was to determine the agreement of cardiac output (CO) measured by four-dimensional echocardiography (4D echo) to simultaneously obtain CO from pulmonary artery catheter (PAC) using thermodilution technique.

MATERIALS AND METHODS

Sixty-three comparable readings from 27 patients scheduled for elective coronary artery bypass were included. All echocardiographic measurements were obtained by one experienced echocardiographer. All echo images were analyzed independently and blinded from PAC-obtained measurements. Analysis was primarily done by Bland and Altman plot. The collected data were further controlled for interobserver bias and image quality.

RESULTS

Differences in CO measurements increased with higher CO, hence values were logarithmically transformed. On the logaritmic scale, the 4D echo underestimated CO by 0.37 l/min compared with PAC, indicating that PAC measurements were 1.45 times higher than the 4D echo (95% confidence interval 1.32-1.52) and limits of agreement 0.97-2.14). The interobserver bias of 4D echo measurement analysis was 0.29 l/min (95% confidence interval 0.16-0.42) and limits of agreement -0.8-1.38). No difference was seen in image quality between comparisons with good agreement compared with comparisons with poor agreement.

CONCLUSION

The agreement between COs by 4D echo and standard PAC thermodilution technique was poor. 4D echo underestimates CO as compared with PAC. This is most likely caused by the analysis software or low frame rate inherent to the technique.

Left atrial function during pregnancy: a three-dimensional echocardiographic study

BACKGROUND

Alteration of diastolic function is considered a sensitive means for detecting changes in the normal cardiac adaptation to pregnancy. Our aim was to evaluate volumetric and functional atrial parameters, using real time three-dimensional echocardiography (RT3DE) in women in early and late third trimester of pregnancy.

METHODS

We studied pregnant women in early third trimester (III-E = gestational age 26-33 weeks), in late third trimester (III-L = gestational age 34-40 weeks), and control nonpregnant women (C). Two-dimensional (2D-Echo) and RT3DE were used to study 3D left atrial (LA) systolic and diastolic stroke volumes and index (LASVI, LAEDVI), emptying fraction, left ventricular and LA cavities.

RESULTS

Although the LA end systolic volume index increased significantly (from 19.42 ± 0.1 to 24.7 ± 3.5 mm(2), P < 0.01), the EF did not change significantly. This was mainly achieved by increasing atrial contraction (A-wave), maintaining cardiac output by increasing heart rate. A decrease in diastolic E-wave, increased atrial kick (A-wave) with reduced E/A ratio, was noted as the pregnancy progressed. Pulmonary pressure increased from 16.9 ± 6.6 to 20.5 ± 2.9 mmHg (P < 0.01), Using 2D-Echo revealed no change in LA diameter from control to III-E and III-L, respectively (from 17.1 ± 2.3 to 16.7 ± 2.6, 17.5 ± 2.2 mm) and area (from 11.7 ± 3.1 to 16.5 ± 2.3, 17.6 ± 1.6 cm(2)). However, using RT3DE, a significant increase in the LASVI, LAEDVI, and LA stroke volume index (from 12.02 ± 2.5 to 14.7 ± 3.2, and 15.1 ± 2.7 mL/m(2)) was detected.

CONCLUSIONS

Enlargement of the LA volume with unchanged blood pressure values, as found using RT3DE, may be part of the adaptation to increased blood volume during pregnancy.

Current clinical applications of transthoracic three-dimensional echocardiography

The advent of three-dimensional echocardiography (3DE) has significantly improved the impact of non-invasive imaging on our understanding and management of cardiac diseases in clinical practice. Transthoracic 3DE enables an easier, more accurate and reproducible interpretation of the complex cardiac anatomy, overcoming the intrinsic limitations of conventional echocardiography. The availability of unprecedented views of cardiac structures from any perspective in the beating heart provides valuable clinical information and new levels of confidence in diagnosing heart disease. One major advantage of the third dimension is the improvement in the accuracy and reproducibility of chamber volume measurement by eliminating geometric assumptions and errors caused by foreshortened views. Another benefit of 3DE is the realistic en face views of heart valves, enabling a better appreciation of the severity and mechanisms of valve diseases in a unique, noninvasive manner. The purpose of this review is to provide readers with an update on the current clinical applications of transthoracic 3DE, emphasizing the incremental benefits of 3DE over conventional two-dimensional echocardiography.

Can transthoracic echocardiography be used to predict fluid responsiveness in the critically ill patient? A systematic review

Introduction. We systematically evaluated the use of transthoracic echocardiography in the assessment of dynamic markers of preload to predict fluid responsiveness in the critically ill adult patient. Methods. Studies in the critically ill using transthoracic echocardiography (TTE) to predict a response in stroke volume or cardiac output to a fluid load were selected. Selection was limited to English language and adult patients. Studies on patients with an open thorax or abdomen were excluded. Results. The predictive power of diagnostic accuracy of inferior vena cava diameter and transaortic Doppler signal changes with the respiratory cycle or passive leg raising in mechanically ventilated patients was strong throughout the articles reviewed. Limitations of the technique relate to patient tolerance of the procedure, adequacy of acoustic windows, and operator skill. Conclusions. Transthoracic echocardiographic techniques accurately predict fluid responsiveness in critically ill patients. Discriminative power is not affected by the technique selected.

3D color-Doppler echocardiography and chronic aortic regurgitation: a novel approach for severity assessment

BACKGROUND

3D echocardiography provides a complete evaluation of the aortic valve and adjacent structures and it improves the assessment of this cardiac region. Three-dimensional color-Doppler echocardiography (3DCDE) evaluation might improve the measurements of the functional regurgitant orifice in patients with Chronic Aortic Regurgitation (CAR).

OBJECTIVES

Our aim was to compare the accuracy of current echo-Doppler methods and 3DCDE for the assessment of CAR severity. The reference method used in this work was the CAR severity determined by means of cardiac magnetic resonance (CMR) METHODS: Thirty-two consecutive patients with an established diagnosis of CAR recruited in our institution comprised our study group. CAR severity was determined by conventional Echo-Doppler methods and by 3DCDE and their results were compared with those obtained by means of CMR.

RESULTS

Mean age was 63.0 ± 13.5 years. Twenty-two patients (68.8%) were men. Compared with the traditional echo-Doppler methods, 3DCDE evaluation had the best linear association with CMR results (3D vena contracta cross sectional area method: r = 0.88; r square = 0.77; p < 0.001. 3D vena contracta cross sectional area/left ventricular outflow tract cross sectional area method: r = 0.87; r square = 0.75; p < 0.001). The ROC analysis showed an excellent area under curve for detection of severe CAR (3D vena contracta cross sectional area method = 0.97; 3D vena contracta cross sectional area/left ventricular outflow tract cross sectional area method = 0.98). Inter- and intra-observer variability for the 3DCDE evaluation was good (ICC = 0.89 and ICC = 0.91 for inter and intra observer variability respectively).

CONCLUSIONS

3DCDE is an accurate and highly reproducible diagnostic tool for estimating CAR severity. Compared with the traditional echo-Doppler methods, 3DCDE has the best agreement with the CMR determined CAR severity. Thus, 3DCDE is a diagnostic method that may improve the therapeutic management of patients with CAR.

Newest echocardiographic techniques for the detection of cardiotoxicity and heart failure during chemotherapy

Chemotherapy-induced cardiotoxicity has become a significant public health issue. Left ventricular ejection fraction is routinely used to monitor cardiotoxicity but fails to detect subtle alterations in cardiac function. Improvements in the measurement of left ventricular ejection fraction, physical or pharmacologic stressors, and novel cardiac functional indices may be useful in the detection of cardiotoxicity. The improvements in the detection and therapy of cancer have led to the emergence of chemotherapy-induced cardiotoxicity. New echocardiographic techniques may be useful in the detection of patients undergoing chemotherapy treatments who could benefit from alternative cancer treatments, therefore decreasing the incidence of cardiotoxicity.

Correlation based 3-D segmentation of the left ventricle in pediatric echocardiographic images using radio-frequency data

Clinical diagnosis of heart disease might be substantially supported by automated segmentation of the endocardial surface in three-dimensional (3-D) echographic images. Because of the poor echogenicity contrast between blood and myocardial tissue in some regions and the inherent speckle noise, automated analysis of these images is challenging. A priori knowledge on the shape of the heart cannot always be relied on, e.g., in children with congenital heart disease, segmentation should be based on the echo features solely. The objective of this study was to investigate the merit of using temporal cross-correlation of radio-frequency (RF) data for automated segmentation of 3-D echocardiographic images. Maximum temporal cross-correlation (MCC) values were determined locally from the RF-data using an iterative 3-D technique. MCC values as well as a combination of MCC values and adaptive filtered, demodulated RF-data were used as an additional, external force in a deformable model approach to segment the endocardial surface and were tested against manually segmented surfaces. Results on 3-D full volume images (Philips, iE33) of 10 healthy children demonstrate that MCC values derived from the RF signal yield a useful parameter to distinguish between blood and myocardium in regions with low echogenicity contrast and incorporation of MCC improves the segmentation results significantly. Further investigation of the MCC over the whole cardiac cycle is required to exploit the full benefit of it for automated segmentation.

Variables influencing the accuracy of 2-dimensional and real-time 3-dimensional echocardiography for assessment of small volumes, areas, and distances: an in vitro study using static tissue-mimicking phantoms

OBJECTIVES

The aim of this study was to assess the validity, accuracy, and reproducibility of real-time 3-dimensional (3D) echocardiography for small distances, areas, and volumes.

METHODS

Real-time 3D echocardiography using matrix technology was performed in small calibrated tissue-mimicking phantoms and compared with 2-dimensional (2D) echocardiography. In a systematic variation of variables on data acquisition and analysis including different 3D workstations (manual disk summation versus semiautomatic border detection), the relative contributions of sources of errors were determined. The clinical relevance of the in vitro findings was assessed in 5 neonates and infants.

RESULTS

Distance calculation was valid (mean relative error ± SD, -0.15% ± 1.2%). Underestimation of areas and volumes was significant for both 2D and 3D echocardiography (area: 2D, -7.0% ± 2.9%; 3D, -6.0% ± 2.8%; volume: 2D, -13.1% ± 4.5%; 3D, -6.7% ± 2.5%; P < .05). Adjustment of compression and gain on data acquisition (difference of the means: 2D, 11.6%; 3D, 17.9%), gain on postprocessing (3D, 3.4%), and the border detection algorithm on analysis (2D, 4.8%; 3D, 16.6%) had a highly significant effect on volume and area calculations (P < .001). In vivo, compression and gain on acquisition (3D, 19.1%) and the 3D workstation on analysis (3D, 22.2%) had a highly significant impact on left ventricular volumetry (P < .001).

CONCLUSIONS

Real-time 3D echocardiography is a reliable method for calculation of small distances, areas, and volumes comparable with the size of the neonatal and infant heart. Variables influencing boundary identification during image acquisition and analysis have a significant impact on 2D and 3D area and volume calculations. Standardized protocols are mandatory to avoid these sources of error in both clinical practice and research.

Three-dimensional simultaneous strain-volume analysis describes left ventricular remodelling and its progression: a pilot study

AIMS

Three-dimensional (3D)-echocardiography speckle imaging allows the evaluation of frame-by-frame strain and volume changes simultaneously. The aim of the present investigation was to describe the strain-volume combined assessment in different patterns of cardiac remodelling.

METHODS AND RESULTS

Fifty patients received a 3D acquisition. Patients were classified as follows: healthy subjects (CNT), previous AMI, and normal ejection fraction (EF; group A); ischaemic cardiomyopathy with reduced EF (group B); hypertrophic/infiltrative cardiomyopathy (group C). Values of 3D strain were plotted vs. volume for each frame to build a strain-volume curve for each case. Peak of radial, longitudinal, and circumferential systolic strain (Rεp, Lεp, and Cεp, respectively), slopes of the curves (RεSl, LεSl, CεSl), and strain to end-diastolic volume (EDV) ratio (Rε/V, Lε/V, Cε/V) were computed for the analysis. Strain-volume curves of the CNT group were steep and clustered, whereas, due to progressive dilatation and reduction of strains, progressive flattening could be demonstrated in groups A and B. Quantitative data supported visual assessment with progressive lower slopes (P< 0.05 for RεSl, CεSl, P= 0.06 for LεSl) and significantly lower ratios (P< 0.01 for Rε/V, Lε/V, and Cε/V). Group C showed an opposite behaviour with slopes and ratios close to those of normal subjects. Correlation coefficients between EDV and slopes of the curves were significant for all the directions of strain (CεSl: r = 0.891; RєSl: r = 0.704; LєSl: r = 0.833; P< 0.0001 for all).

CONCLUSION

We measured left ventricular volumes and strain by 3D-echo and obtained strain-volume curve to evaluate their behaviour in remodelling. A distinctive and progressive pattern consistent with pathophysiology was observed. The analysis here shown could represent a new non-invasive method to assess myocardial mechanics and its relationship with volumes.

Three-dimensional echocardiography for left ventricular quantification: fundamental validation and clinical applications

One of the earliest applications of clinical echocardiography is evaluation of left ventricular (LV) function and size. Accurate, reproducible and quantitative evaluation of LV function and size is vital for diagnosis, treatment and prediction of prognosis of heart disease. Early three-dimensional (3D) echocardiographic techniques showed better reproducibility than two-dimensional (2D) echocardiography and narrower limits of agreement for assessment of LV function and size in comparison to reference methods, mostly cardiac magnetic resonance (CMR) imaging, but acquisition methods were cumbersome and a lack of user-friendly analysis software initially precluded widespread use. Through the advent of matrix transducers enabling real-time three-dimensional echocardiography (3DE) and improvements in analysis software featuring semi-automated volumetric analysis, 3D echocardiography evolved into a simple and fast imaging modality for everyday clinical use. 3DE provides the possibility to evaluate the entire LV in three spatial dimensions during the complete cardiac cycle, offering a more accurate and complete quantitative evaluation the LV. Improved efficiency in acquisition and analysis may provide clinicians with important diagnostic information within minutes. The current article reviews the methodology and application of 3DE for quantitative evaluation of the LV, provides the scientific evidence for its current clinical use, and discusses its current limitations and potential future directions.

Surrogate markers of cardiovascular disease in CKD: what's under the hood?

Although clinical cardiovascular outcomes, such as heart attack, stroke, and sudden cardiac death, have a dramatic onset, they result from prolonged exposure to an ever-growing array of risk factors. Several noninvasive procedures are available to assess the cumulative effect of these exposures with the goal of more precisely estimating a person's cardiovascular risk. These include ankle-brachial index, which provides an estimation of obstruction in major-vessel lumen caliber; carotid ultrasound, which evaluates carotid intima-media thickness and plaque, visibly quantifying atherosclerotic burden; aortic pulse wave velocity, which provides a measure of large-artery stiffness; and echocardiography, which measures left ventricular mass, providing a measure of subclinical hypertensive heart disease. In this narrative review, we discuss the role of each of these measures, with a particular emphasis on patients with chronic kidney disease.

WEB downloadable software for training in cardiovascular hemodynamics in the (3-D) stress echo lab

When a physiological (exercise) stress echo is scheduled, interest focuses on wall motion segmental contraction abnormalities to diagnose ischemic response to stress, and on left ventricular ejection fraction to assess contractile reserve. Echocardiographic evaluation of volumes (plus standard assessment of heart rate and blood pressure) is ideally suited for the quantitative and accurate calculation of a set of parameters allowing a complete characterization of cardiovascular hemodynamics (including cardiac output and systemic vascular resistance), left ventricular elastance (mirroring left ventricular contractility, theoretically independent of preload and afterload changes heavily affecting the ejection fraction), arterial elastance, ventricular arterial coupling (a central determinant of net cardiovascular performance in normal and pathological conditions), and diastolic function (through the diastolic mean filling rate). All these parameters were previously inaccessible, inaccurate or labor-intensive and now become, at least in principle, available in the stress echocardiography laboratory since all of them need an accurate estimation of left ventricular volumes and stroke volume, easily derived from 3 D echo.

Aims of this paper are: 1) to propose a simple method to assess a set of parameters allowing a complete characterization of cardiovascular hemodynamics in the stress echo lab, from basic measurements to calculations 2) to propose a simple, web-based software program, to learn and training calculations as a phantom of the everyday activity in the busy stress echo lab 3) to show examples of software testing in a way that proves its value.

The informatics infrastructure is available on the web, linking to http://cctrainer.ifc.cnr.it

A comparison of retrospectively self-gated magnetic resonance imaging and high-frequency echocardiography for characterization of left ventricular function in mice

Non-invasive imaging methods like echocardiography and magnetic resonance imaging (MRI) are very valuable in longitudinal follow-up studies of cardiac function in small animals. To be able to compare results from studies using different methods, and explain possible differences, it is important to know the agreement between these methods. As both self-gated high-field MRI and high-frequency echocardiography (hf-echo) M-mode are potential methods for evaluation of left ventricular (LV) function in healthy mice, our aim was to assess the agreement between these two methods. Fifteen healthy female C57BL/6J mice underwent both self-gated MRI and hf-echo during the same session of light isoflurane anaesthesia. LV dimensions were estimated offline, and agreement between the methods and reproducibility for the two methods assessed using Bland-Altman methods. In summary, hf-echo M-mode had better inter-observer repeatability than self-gated MRI for all measured parameters. Compared with hf-echo, systolic posterior wall thicknesses were significantly higher when measured by MRI, while diastolic anterior wall thicknesses were found to be significantly smaller. MRI measurements of diastolic LV diameter were also higher using MRI, resulting in larger fractional shortening values compared with the values obtained by hf-echo. In conclusion, hf-echo M-mode is easy to apply, has high temporal and spatial resolution, and good reproducibility. Self-gated MRI might be advantageous in cases of abnormal LV geometry and heterogeneous regional myocardial function, especially with improvements in spatial resolution. The moderate agreement between the methods must be taken into account when comparing studies using the two modalities.

Three-dimensional echocardiography using single-heartbeat modality decreases variability in measuring left ventricular volumes and function in comparison to four-beat technique in atrial fibrillation

Background

Three dimensional echocardiography (3DE) approaches the accuracy of cardiac magnetic resonance in measuring left ventricular (LV) volumes and ejection fraction (EF). The multibeat modality in comparison to single-beat (SB) requires breath-hold technique and regular heart rhythm which could limit the use of this technique in patients with atrial fibrillation (AF) due to stitching artifact. The study aimed to investigate whether SB full volume 3DE acquisition reduces inter- and intraobserver variability in assessment of LV volumes and EF in comparison to four-beat (4B) ECG-gated full volume 3DE recording in patients with AF.

Methods

A total of 78 patients were included in this study. Fifty-five with sinus rhythm (group A) and 23 having AF (group B). 4B and SB 3DE was performed in all patients. LV volumes and EF was determined by these two modalities and inter- and intraobserver variability was analyzed.

Results

SB modality showed significantly lower inter- and intraobserver variability in group B in comparison to 4B when measuring LV volumes and EF, except for end-systolic volume (ESV) in intraobserver analysis. There were significant differences when calculating the LV volumes (p < 0.001) and EF (p < 0.05) with SB in comparison to 4B in group B.

Conclusion

Single-beat three-dimensional full volume acquisition seems to be superior to four-beat ECG-gated acquisition in measuring left ventricular volumes and ejection fraction in patients having atrial fibrillation. The variability is significantly lower both for ejection fraction and left ventricular volumes.

Early influences on cardiovascular and renal development

The hypothesis that a developmental component plays a role in subsequent disease initially arose from epidemiological studies relating birth size to both risk factors for cardiovascular disease and actual cardiovascular disease prevalence in later life. The findings that small size at birth is associated with an increased risk of cardiovascular disease have led to concerns about the effect size and the causality of the associations. However, recent studies have overcome most methodological flaws and suggested small effect sizes for these associations for the individual, but an potential important effect size on a population level. Various mechanisms underlying these associations have been hypothesized, including fetal undernutrition, genetic susceptibility and postnatal accelerated growth. The specific adverse exposures in fetal and early postnatal life leading to cardiovascular disease in adult life are not yet fully understood. Current studies suggest that both environmental and genetic factors in various periods of life may underlie the complex associations of fetal growth retardation and low birth weight with cardiovascular disease in later life. To estimate the population effect size and to identify the underlying mechanisms, well-designed epidemiological studies are needed. This review is focused on specific adverse fetal exposures, cardiovascular adaptations and perspectives for new studies.

Validation of 3D echocardiographic assessment of left ventricular volumes, mass, and ejection fraction in neonates and infants with congenital heart disease: a comparison study with cardiac MRI

BACKGROUND

quantitative assessment and validation of left ventricular (LV) volumes and mass in neonates and infants with complex congenital heart disease (CHD) is important for clinical management but has not been undertaken. We compared matrix-array 3D echocardiography (3D echo) measurements of volumes, mass, and ejection fraction (EF) with those measured by cardiac MRI in young patients with CHD and small LVs because of either young age or LV hypoplasia.

METHODS AND RESULTS

thirty-five patients aged <4 years (median, 0.8 years) undergoing MRI were prospectively enrolled. Three-dimensional echo was acquired immediately after MRI, and volume, mass, and EF measurements, using summation of discs methodology, were compared with MRI. Three-dimensional echo end-diastolic volume (24.4±15.7 versus 24.8±46.4 mL; P=0.01; intraclass correlation coefficient [ICC], 0.96) and end-systolic volume (12.3±8.6 versus 9.6±6.8 mL; P<0.001; ICC, 0.90) correlated with MRI with small mean differences (-0.49 mL [P=0.6] and 2.7 mL [P=0.001], respectively). Three-dimensional echo EF was smaller than MRI by 9.3% (P<0.001), and 3D echo LV mass measurements were comparable to MRI (17.3±10.3 versus 17.6±12 g; P<0.77; ICC, 0.93), with a small mean difference (1.1 g; P=0.28). There was good intra- and interobserver reliability for all measurements.

CONCLUSIONS

in neonates and infants with CHD and small LVs (age appropriate or hypoplastic), matrix-array 3D echo measurements of mass and volumes compare well with MRI, providing an important modality for ventricular size and performance analysis in these patients, particularly in those with left-side heart obstructive lesions.