Estimation of the right ventricular volume and ejection fraction by transthoracic three-dimensional echocardiography. A validation study using magnetic resonance imaging

Effect of long term CPAP therapy on cardiac parameters assessed with cardiac MRI

The obstructive sleep apnoea syndrome (OSAS) is a disorder with a high prevalence and is associated with an elevated cardiovascular risk and increased morbidity and mortality. For longitudinal studies and functional analysis cardiac MRI is regarded as the gold standard. Aim of this study was to evaluate the long-term effect of continuous positive airway pressure (CPAP) therapy on cardiac functional parameters with cardiac Magnetic Resonance Imaging (cMRI). 54 patients with OSAS (mean apnea hypopnea index-AHI: 31) were prospectively enrolled in this study and cMRI was performed before and after 7 months of CPAP therapy. Data were acquired on a 1.5 T MRI and right and left ventricular cardiac function were analysed. CPAP treatment was considered compliant when used ≥ 4 h per night. 24-h blood pressure was measured at baseline and follow up. 33 patients could be assigned to the compliance group. Left ventricular stroke volume (LV SV) and right ventricular ejection fraction (RV EF) improved significantly with CPAP therapy (LV SV from 93 ± 19 to 99 ± 20 ml, p = 0.02; RV EF from 50 ± 6 to 52 ± 6%, p = 0.04). All other cardiac parameters did not change significantly while mean systolic and diastolic blood pressure improved significantly (p < 0.01). 21 patients were assigned to the non-compliance group and were considered as a control group. There were no relevant differences in cardiac parameters between baseline and follow up examination in these patients. CPAP therapy seems to improve LV SV, RV EF, systolic and diastolic blood pressure in OSAS patients, but reproducibility of our results need to be confirmed in a larger patient population.

Assessing Right Ventricular Function in the Perioperative Setting, Part II: What About Catheters?

An-depth assessment of right ventricular function is important in a many perioperative settings. After exploring 2-dimensional echo-based evaluation, other proposed monitoring modalities are discussed. Pressure-based methods of right ventricular appraisal is discussed. Flow-based assessment is reviewed. An overview of the state of current right ventricular 3-dimensional echocardiography and its potential to construct clinical pressure-volume loops in conjunction with pressure measurements is provided. An overview of right ventricular assessment modalities that do not rely on 2-dimensional echocardiography is discussed. Tailored selection of monitoring modalities can be of great benefit for the perioperative physician. Integrating modalities offers optimal estimations of right ventricular function.

A Comparison of Left- and Right-Sided Strain Software for the Assessment of Intraoperative Right Ventricular Function

OBJECTIVE

To compare intraoperative right ventricular (RV) strain measurements made with left ventricular (LV) strain software commonly found on the echocardiography machine (Philips QLAB chamber motion quantification, version 10.7, Philips, Amsterdam, The Netherlands), with offline analysis using the dedicated RV strain software (EchoInsight, version 2.2.6.2230, Epsilon Imaging, Ann Arbor, MI).

DESIGN

Prospective, nonrandomized, observational study.

SETTING

Single tertiary level, university-affiliated hospital.

PARTICIPANTS

The study comprised 48 patients undergoing transesophageal echocardiography for cardiac or noncardiac surgery.

INTERVENTIONS

Two-dimensional (2D) and 3-dimensional (3D) images of the right ventricle were obtained. Intraoperative 2D images were analyzed in real time for RV free wall strain (FWS) and global longitudinal strain (GLS) using QLAB chamber motion quantification (CMQ) LV strain software on the echocardiography machine. Two dimensional images were then analyzed offline to determine the RV FWS and GLS using EchoInsight RV-specific strain software. Three-dimensional images were then analyzed offline to detemine the 3D RV ejection fraction (3D RV EF) using TomTec 4D RV function (Unterschleissheim, Germany). Spearman's correlation and Bland-Altman analyses were used to characterize the relationship between RV strain measurements. Both types of strain measurements were compared to a reference standard of 3D RV EF.

MEASUREMENTS AND MAIN RESULTS

Intraoperative RV strain measurements using LV-specific strain software correlated with offline RV strain measurements using the RV-specific strain software (FWS rho = 0.85; GLS rho = 0.81). The bias and limits of agreement were 0.75% (- 6.66 to 8.17) for FWS and -4.53% (-11.55 to 2.50) for GLS. The sensitivity and specificity for RV dysfunction for the intraoperative LV-specific software were 94% (95% confidence interval [CI] 73-100) and 70% (95% CI 51-85), respectively, for RV FWS and 94% (95% CI 73-100) and 67% (95% CI 47-83), respectively, for RV GLS. The sensitivity and specificity for RV dysfunction for the offline RV-specific software were 89% (95% CI 65-99) and 73% (95% CI 54-88), respectively, for RV FWS and 94% (95% CI 73-100) and 30% (95% CI 15-49), respectively, for RV GLS.

CONCLUSION

Intraoperative RV strain measurements using LV-specific strain software commonly available on the echocardiography machine (QLAB CMQ) correlate with offline RV strain measurements using RV-specific strain software (EchoInsight). The bias and limits of agreement for these left- and right-sided strain software suggest that these 2 measures of RV function cannot be used interchangeably. Both, however, were sensitive measures of RV dysfunction and therefore are likely clinically relevant.

A systematic approach to 3D echocardiographic assessment of the aortic root

[first paragraph of article]Severe aortic regurgitation (AR) and/or severe abnormalities of the aortic root and the tubular ascending aorta (TAA) are indications for surgical treatment. The correct diagnosis, the choice of optimal treatment, as well as optimal timing of surgery, mainly depend on findings obtained by echocardiography - which is usually the initial diagnostic modality applied in clinical practice. Therefore, an appropriate morphological and functional quantification of the aortic valve (AV) and the aortic root complex is required. Aside from the need of standardization to provide a precise objective evaluation, the use of modern echocardiographic technologies - especially 3D-echocardiography -are less often implemented in clinical routine. The present manuscript focuses on the advantages of transthoracic and transesophageal 3D-echocardiography (TTE, TEE) for an improved assessment of the AV and the aortic root complex to provide accurate and comprehensive measurements for making the correct diagnosis and defining further therapeutic strategies.

Analysis of chronic aortic regurgitation by 2D and 3D echocardiography and cardiac MRI

Purpose The study compares the feasibility of the quantitative volumetric and semi-quantitative approach for quantification of chronic aortic regurgitation (AR) using different imaging modalities. Methods Left ventricular (LV) volumes, regurgitant volumes (RVol) and regurgitant fractions (RF) were assessed retrospectively by 2D, 3D echocardiography and cMRI in 55 chronic AR patients. Semi-quantitative parameters were assessed by 2D echocardiography. Results 22 (40%) patients had mild, 25 (46%) moderate and 8 (14%) severe AR. The quantitative volumetric approach was feasible using 2D, 3D echocardiography and cMRI, whereas the feasibility of semi-quantitative parameters varied considerably. LV volume (LVEDV, LVESV, SVtot) analyses showed good correlations between the different imaging modalities, although significantly increased LV volumes were assessed by cMRI. RVol was significantly different between 2D/3D echocardiography and 2D echocardiography/cMRI but was not significantly different between 3D echocardiography/cMRI. RF was not statistically different between 2D echocardiography/cMRI and 3D echocardiography/cMRI showing poor correlations (r < 0.5) between the different imaging modalities. For AR grading by RF, moderate agreement was observed between 2D/3D echocardiography and 2D echocardiography/cMRI and good agreement was observed between 3D echocardiography/cMRI. Conclusion Semi-quantitative parameters are difficult to determine by 2D echocardiography in clinical routine. The quantitative volumetric RF assessment seems to be feasible and can be discussed as an alternative approach in chronic AR. However, RVol and RF did not correlate well between the different imaging modalities. The best agreement for grading of AR severity by RF was observed between 3D echocardiography and cMRI. LV volumes can be verified by different approaches and different imaging modalities.

Adult echocardiographic nomograms: overview, critical review and creation of a software for automatic, fast and easy calculation of normal values

There is a crescent interest on normal adult echocardiographic values and the introduction of new deformation imaging and 3D parameters pose the issue of normative data. A multitude of nomograms has been recently published, however data are often fragmentary, difficult to find, and their strengths/limitations have been never evaluated.

AIMS

(I) to provide a review of current echocardiographic nomograms; (II) to generate a tool for easy and fast access to these data. A literature search was conducted accessing the National Library of Medicine using the keywords: 2D/3D echocardiography, strain, left/right ventricle, atrial, mitral/tricuspid valve, aorta, reference values/nomograms/normal values. Adding the following keywords, the results were further refined: range/intervals, myocardial velocity, strain rate and speckle tracking. Forty one published studies were included. Our study reveals that for several of 2D/3D parameters sufficient normative data exist, however, a few limitations still persist. For some basic parameters (i.e., mitral/tricuspid/pulmonary valves, great vessels) and for 3D valves data are scarce. There is a lack of studies evaluating ethnic differences. Data have been generally expressed as mean values normalised for gender and age instead of computing models incorporating different variables (age/gender/body sizes) to calculate z scores. To summarize results a software (Echocardio-Normal Values) who automatically calculate range of normality for a broad range of echocardiographic measurements according to age/gender/weight/height, has been generated. We provide an up-to-date and critical review of strengths/limitation of current adult echocardiographic nomograms. Furthermore we generated a software for automatic, easy and fast access to multiple echocardiographic normative data.

Assessment of right ventricular structure and function in pulmonary hypertension

Right ventricular function plays an important role in determining cardiac symptoms and exercise capacity in chronic heart failure. It is known that right ventricle has complex anatomy and physiology. The purpose of this review paper is to demonstrate the best assessment of the right ventricle with current echocardiography. Echocardiography can assess sufficiently right ventricular structure and function and also suggest prognosis in pulmonary hypertension patients, especially with the use of modern imaging techniques. Finally, the new imaging modality of real time three dimensional echocardiography is interchangeable to cardiac magnetic resonance in reproducibility and accuracy.

Accuracy of knowledge-based reconstruction for measurement of right ventricular volume and function in patients with tetralogy of Fallot

We tested the accuracy and reproducibility of knowledge-based reconstruction (KBR) for measuring right ventricular (RV) volume and function. KBR enables rapid assessment of the right ventricle from sparse user input by referencing a database. KBR generates a 3-dimensional surface to fit points that the user enters at anatomic landmarks. We measured the RV volume using KBR from magnetic resonance images in 20 patients with repaired tetralogy of Fallot at end-diastole and end-systole. We entered points in the long- and short-axis and/or oblique views. The true volume was computed by manually tracing the RV borders for 3-dimensional reconstruction using the piecewise smooth subdivision surface method. The reference database included 54 patients with tetralogy of Fallot patients. The KBR values agreed closely with the true values for the end-diastolic volume (r = 0.993), end-systolic volume (r = 0.992), and ejection fraction (EF; r = 0.930). KBR slightly overestimated the end-diastolic volume (4 +/- 10 ml, p = NS), end-systolic volume (1 +/- 9 ml, p = NS), and EF (4 +/- 3%, p = NS). No bias in the error was found by Bland-Altman analysis (p = NS for end-diastolic and end-systolic volume and EF). The KBR volumes had approached the true volumes (235 +/- 93 vs 243 +/- 93, p = 0.012, r = 0.978 for end-diastolic and end-systolic volumes combined) already after the first run and the entry of 19 +/- 3 points. In conclusion, KBR provided accurate measurement of the RV volume and EF with minimal user input. KBR is a clinically feasible alternative to full manual tracing of the heart borders from imaging data.

Right ventricle three-dimensional echography in corrected tetralogy of fallot: accuracy and variability

AIMS

To evaluate right ventricular (RV) volume and ejection fraction (EF) in adult normal subjects and repaired tetralogy of Fallot (ToF) with 3D trans-thoracic echocardiography (3DE) and a semi-automatic border detection algorithm.

METHODS AND RESULTS

Fourteen healthy volunteers and 20 patients with repaired ToF (mean age 31 +/- 14) underwent 3DE and MRI within the same day. Right ventricular end-systolic volume (ESV) and end-diastolic volume (EDV) and EF were measured by two observers using 3DE and compared with MRI measurements. Intra- and interobserver variability of 3DE and agreement between both methods were evaluated using Bland-Altman analysis. Over or underestimation of 3DE in comparison to MRI was assessed using paired t-test. Intra- and interobserver variability of 3DE was excellent with intraclass coefficient of correlation (ICC) ranging from 0.85 to 0.99 and from 0.85 to 0.98, respectively. Three-dimensional echocardiography underestimated ESV and EDV (P < 0.001) but agreement between 3DE and MRI was excellent (ICC = 0.88 and 0.87, respectively). Ejection fraction was 47.7 +/- 7.8 with 3DE and 47.9 +/- 6.7 with MRI, agreement between both methods was good (ICC = 0.72).

CONCLUSION

Three-dimensional echocardiography combined to semi-automated quantification software shows fair agreement with MRI for RV volumes and EF measurement in patients with repaired ToF and adequate intra- and interobserver variability. These results suggest applicability for serial follow-up of patients with right heart congenital disease. However, the accuracy of 3DE echo diminishes with larger RV volumes, in part due to current difficulty to include the entire RV in the imaged sector. Technical progress in transducers beam geometry is likely to address this issue.

Non-invasive investigations of the right heart: how and why?

The importance of right ventricular (RV) function in the clinical management of patients with cardiopulmonary disorders is now well recognized. However, due to both its shape and location and to the load dependence of its ejection fraction, accurate evaluation of its function is still a challenge. Echocardiography allows morphological, hemodynamic and functional assessment of the right heart. Displacement and deformation parameters derived from new techniques are promising tools. 3D echocardiography also has a potential interest in the quantification of RV volumes and ejection fraction. Radionuclide technique allows an easy and accurate measurement of right ventricular ejection fraction. MRI remains nowadays the technique of choice for the quantification of volumes and function of the RV. All these techniques have proven their interest in various diseases affecting the right heart. RV function is an important prognostic factor in heart failure and is a major component of functional capacity in such patients. In pulmonary arterial hypertension, echocardiography is the best tool for the routine follow-up of patients. Finally, all these non-invasive techniques of investigation of the right heart enable the diagnosis of specific right ventricular damage such as myocardial infarction or arrhythmogenic right ventricular dysplasia.

Assessment of right ventricular function by real-time three-dimensional echocardiography improves accuracy and decreases interobserver variability compared with conventional two-dimensional views

AIMS

Two-dimensional echocardiographic (2DE) assessment of right ventricular (RV) function is difficult, often resulting in inconsistent RV evaluation. Real-time three-dimensional echocardiography (RT3DE) allows the RV to be viewed in multiple planes, which can potentially improve RV assessment and limit interobserver variability when compared with 2DE.

METHODS AND RESULTS

Twenty-five patients underwent 2DE and RT3DE. Views of 2DE (RV inflow, RV short axis, and apical four-chamber) were compared with RT3DE views by four readers. RT3DE data sets were sliced from anterior-posterior (apical view) and from base to apex (short axis) to obtain six standardized planes. Readers recorded the RV ejection fraction (RVEF) from 2DE and RT3DE images. RVEF recorded by RT3DE (RVEF(3D)) and 2D (RVEF(2D)) were compared with RVEF by disc summation (RVEF(DS)), which was used as a reference. Interobserver variability among readers of RVEF(3D) and RVEF(2D) was then compared. Overall, mean RVEF(DS), RVEF(3D), and RVEF(2D) were 37 +/- 11%, 38 +/- 10%, 41 +/- 10%, respectively. The mean difference of RVEF(3D)-RVEF(DS) was significantly less than RVEF(2D)-RVEF(DS) (3.7 +/- 4% vs. 7.1 +/- 5%, P = 0.0066, F-test). RVEF(3D) correlated better with RVEF(DS) (r = 0.875 vs. r = 0.69, P = 0.028, t-test). RVEF(3D) was associated with a 39% decrease in interobserver variability when compared with RVEF(2D) [standard deviation of mean difference: 3.7 vs. 5.1, (RT3DE vs. 2DE), P = 0.018, t-test].

CONCLUSIONS

RT3DE provides improved accuracy of RV function assessment and decreases interobserver variability when compared with 2D views.

The right ventricle in cardiac surgery, a perioperative perspective: I. Anatomy, physiology, and assessment

The importance of right ventricular (RV) function in cardiovascular disease and cardiac surgery has been recognized for several years. RV dysfunction has been shown to be a significant prognostic factor in heart failure, congenital heart disease, valvular disease, and cardiac surgery. In the first of our two articles, we will review key features of RV anatomy, physiology, and assessment. In the first article, the main discussion will be centered on the echographic assessment of RV structure and function. In the second review article, pathophysiology, clinical importance, and management of RV failure in cardiac surgery will be discussed.

Rapid and accurate quantification of right ventricular volume and stroke volume by real-time 3-dimensional triplane echocardiography

BACKGROUND

Previous studies have demonstrated that 3-Dimensional (3-D) echocardiography can determine right ventricular (RV) volume accurately. However, this technique has not been feasible in everyday clinical practice because of the necessity of time-consuming off-line processes.

HYPOTHESIS

A newly developed real-time 3-D triplane echocardiography, which acquires 3 apical rotational cross-sectional images simultaneously, holds the promise to resolve these problems.

METHODS AND RESULTS

Sixteen excised formalin fixed porcine hearts and 24 healthy human subjects underwent real-time 3-D triplane echocardiography. In an anatomic in vitro study, the actual volume of RV was obtained by spilling water in the RV cavity into a graduated cylinder for measurement, which served as a reference standard for comparison. For healthy subjects, the RV stroke volume (SV) was measured by triplane echocardiography which was compared with the left ventricular (LV) SV obtained by conventional 2-Dimensional echocardiography (2-DE). Excellent correlation and agreement between 3-D triplane imaging derived RV volume and the actual one for excised porcine hearts were observed (r = 0.979, p < 0.001, mean difference 2.2 mL). In healthy human subjects, good correlation and agreement between 3-D triplane imaging derived RV SV and LV SV measured by 2-DE were obtained (r = 0.970, p < 0.001, mean difference 5.9 mL).

CONCLUSIONS

Real-time 3-D triplane echocardiography provides us a new method for rapid and accurate quantification of RV volume. Furthermore, this new method holds the promise for evaluating RV volume and SV in routine clinical practice.

Atrial natriuretic peptide and three-dimensional echocardiography after transcatheter closure of atrial septal defect

Background

Atrial septal defect (ASD) accounts for 10% of all congenital heart lesions and represent the third most congenital cardiac defect seen in adults. Atrial natriuretic peptide (ANP) is an important regulator of the sodium and volume homeostasis. This study was designed to investigate the changes in plasma ANP concentrations and three-dimensional echocardiography (3DE) measurements of cardiac volume in patients with ASD during transcatheter closure of defect.

Methods

Plasma ANP concentrations and transthoracic 3DE measurements of right ventricular volume were performed in 46 patients with ASD before closure, and at 3 days after closure. 22 healthy subjects matched for age, sex served as control subjects.

Results

The 46 patients (20 men, 26 women; mean age 26.32 ± 13.28, range 6 to 63 years) were diagnosed to secundum ASD (the stretched diameters of ASD were from 9~36(25.34 ± 7.80 mm), and had been successfully placed Amplatzer septal occluder (the sizes of occluder were from 11 to 40 mm). The results showed that compared with control subjects, plasma ANP concentrations were elevated in patients with ASD. Plasma ANP concentrations positively correlated significantly with pulmonary artery pressure (PAP) (r = 0.74, p < 0.05) and 3DE measurements of cardiac volumes (right ventricular end-diastolic (r = 0.50, p < 0.05) and end-systolic volume (r = 0.50, p < 0.05) and negatively correlated with RVEF (r = -0.38, p < 0.05). Transthoracic 3DE measurements of right ventricular volume and plasma ANP concentrations decreased significantly at 3 days after closure (p < 0.05) compared with it before closure.

Conclusion

Plasma ANP concentrations were markedly elevated in patients with pulmonary arterial hypertension and right ventricular volume overload and decreased significantly after closure of ASD. This study suggested that ANP may help to identify patients with ASD complicated by pulmonary arterial hypertension and right ventricular volume overload that demanded early intervention and may become effective marker for evaluating changes in cardiac load after transcatheter ASD closure.

Impaired right ventricular function in adenotonsillar hypertrophy

OBJECTIVE

Adenotonsillar hypertrophy (ATH) causing upper airway obstruction and obstructive sleep apnea (OSA) syndrome and may lead to the pulmonary hypertension and cor pulmonale. This study was designed to determine the clinical value of right ventricular (RV) myocardial performance index (MPI) in ATH. The effects of adenotonsillectomy on MPI were also assessed.

METHODS

Twenty-one children with grade 3 and grade 4 ATH and 21 age-and-sex matched healthy children were enrolled. MPI, defined as the sum of isovolumetric contraction and relaxation time divided by ejection time, was measured by using Doppler echocardiography preoperatively and postoperatively in all subjects. The quality of life in children was also assessed with obstructive sleep disorder questionnaire (OSA-18).

RESULTS

The RV MPI in patients with ATH was significantly higher than the control group (0.41 +/- 0.06 vs. 0.29 +/- 0.07; P < .001). It showed a strong correlation with mean pulmonary artery pressure and OSA-18 survey score (r = 0.71; P < .005 and (r = 0.64; P < .01, respectively). The RV MPI and OSA-18 survey score decreased significantly after the relief of upper airway obstruction by adenotonsillectomy (from 0.41 +/- 0.06 to 0.31 +/- 0.03; P < .001 and from 83 +/- 27 to 36 +/- 12; P < .0001, respectively). The RV MPI in postoperative group was similar to control group.

CONCLUSION

Our findings support that advanced stage of ATH is associated with impaired RV functions, which were recovered postoperatively.

Three-dimensional Echocardiographic Evaluation of Right Ventricular Volume and Function in Pediatric Patients: Validation of the Technique

The right ventricle (RV) is the main ventricular chamber in many congenital heart diseases before and after surgical correction, and it is the most important determinant of outcome in postoperative tetralogy of Fallot and other complex malformations. Unfortunately its irregular crescentic shape does not allow the use of the geometric assumption used for the left ventricle. Many methods have been suggested in the literature to overcome this problem, none fully reliable. The introduction of volume-rendered 3-dimensional (3D) reconstruction of echocardiography images provides a tool for the direct measurement of cardiac chambers, not based on geometric assumptions. The aim of this research study was to determine the accuracy of 3D echocardiography (3DE) to measure RV volumes in pediatric patients with secundum atrial septal defects, compared with direct volume measurements performed during the intervention. We performed 3DE study in the operating department, with the patient anesthetized, intubated, and ventilated before the surgical procedure. Sequential 2-dimensional echocardiographic images for subsequent 3D rendering were acquired using an ultrasound machine with a transthoracic 4-MHz rotational or 5-MHz transesophageal omniplane probe; in the last 5 patients a machine was used that was equipped with a 3600-crystal real-time 3D probe. To validate the 3DE measurements, these were compared with the volume of the RV directly measured in the operating department, at the end of the surgical procedure, injecting saline solution through the tricuspid valve, using a graduate syringe. Among 25 pediatric patients enrolled in the study, with an age range of 1 and 14 years (mean 4 years) and a weight range of 8.5 to 57.4 kg (mean 18.6 kg), in 23 a mean of 3 echocardiographic acquisitions were performed and compared with the direct measurement. A close comparison was found between RV volumes measured by 3DE and direct volume measurements (P < .00001). The regression line, shifted toward the y axis, which describes the 3DE volumes, indicated that the echocardiographic measures overestimate the surgical ones. In our study this overestimation had the mean of 9% with values comprised between 3% and 19%. The coefficient of repeatability was 4.79 mL with all the values within this range (2 SD of the mean). We conclude that 3DE provides an accurate measurement of RV volume in pediatric patients with RV volume overload. It is a reliable, noninvasive, and nongeometric method of evaluation of the volume of this chamber, and can be considered a precious tool in the armamentarium of the pediatric cardiologist.

Accuracy and reproducibility of real-time three-dimensional echocardiography for assessment of right ventricular volumes and ejection fraction in children

BACKGROUND

Measurement of right ventricular (RV) volumes and ejection fraction (EF) by two-dimensional echocardiography has limited accuracy and reproducibility because of the complex RV geometry.

OBJECTIVES

This study sought to validate real-time three-dimensional echocardiography (RT3DE) using a disk summation method for assessment of RV volumes and RVEF in children by comparing it with magnetic resonance imaging (MRI) measurements.

METHODS

A total of 20 children (mean age 10.6 +/- 2.8 years) were studied. Transthoracic RT3DE was performed using a RT3DE system to acquire full-volume RT3DE data sets from apical windows and data were processed offline using a software package. RV end-systolic volume and end-diastolic volume (EDV) were measured using a disk summation method by manually tracing the endocardial borders. RVEF was calculated as: RVEF = (EDV - end-systolic volume)/EDV x 100%. All participants also underwent MRI studies for comparison of RV indexes.

RESULTS

Of the 20 children, 3 were excluded because of poor or incomplete RV images (two RT3DE and one MRI study). For the remaining 17 children, good correlation and agreement between RT3DE and MRI were found (RVEDV: r = 0.98, P < .001, mean difference = -7.0 +/- 9.0 mL, P < .01; RV end-systolic volume: r = 0.96, P < .001, mean difference = -3.2 +/- 7.1 mL, P > .05; RVEF: r = 0.89, P < .001, mean difference = -0.3 +/- 7.1%, P > .05). The intraobserver and the interobserver variabilities ranged from -1.1% to 5.8%.

CONCLUSION

Measurement of RV volumes and EF by RT3DE is feasible, accurate, and reproducible in children compared with MRI measurements.

Quantification of right ventricular volumes and function by real time three-dimensional echocardiographic longitudinal axial plane method: validation in the clinical setting

BACKGROUND

Measurement of right ventricular (RV) volumes and right ventricular ejection fraction (RVEF) by three-dimensional echocardiographic (3DE) short-axis disc summation method has been validated in multiple studies. However, in some patients, short-axis images are of insufficient quality for accurate tracing of the RV endocardial border. This study examined the accuracy of long-axis analysis in multiple planes (longitudinal axial plane method) for assessment of RV volumes and RVEF.

METHODS

3DE images were analyzed in 40 subjects with a broad range of RV function. RV end-diastolic (RVEDV) and end-systolic volumes (RVESV) and RVEF were calculated by both short-axis disc summation method and longitudinal axial plane method.

RESULTS

Excellent correlation was obtained between the two methods for RVEDV, RVESV, and RVEF (r = 0.99, 0.99, 0.94, respectively; P < 0.0001 for all comparisons).

CONCLUSION

3DE longitudinal-axis analysis is a promising technique for the evaluation of RV function, and may provide an alternative method of assessment in patients with suboptimal short-axis images.

Variables Influencing the Accuracy of Right Ventricular Volume Assessment by Real-time 3-Dimensional Echocardiography: An In Vitro Validation Study

BACKGROUND

Preliminary experience with matrix-array real-time (RT) 3-dimensional echocardiography (3DE) in pediatric patients has demonstrated consistently lower right ventricular volume (RVV) compared with magnetic resonance imaging. Our hypothesis was that variables in RT 3DE acquisition and offline analysis, including gain settings, thickness, and orientation of disks, could alter RVV measurements.

METHODS

Displacements of water from latex models derived from excised lamb hearts were used for comparison. RT 3DE volume acquisitions were performed using a matrix-array probe (2-4 MHz); RVVs were calculated offline using summation of disks method.

RESULTS

No significant difference and excellent agreement was found for comparison of RT 3DE with displacement of water using 5-mm cut planes, optimal gain settings, and short-axis tracings. Different gain settings and long-axis tracings significantly affected RVV. A slice thickness of 13 mm or greater affected volume measurements.

CONCLUSIONS

RT 3DE can accurately measure RVV. Specific variables will alter volumes measurements and must be considered in clinical studies.

Normal Values of Right Ventricular Size and Function by Real-time 3-Dimensional Echocardiography: Comparison with Cardiac Magnetic Resonance Imaging

BACKGROUND

Assessment of right ventricular function by 2-dimensional echocardiography (2DECHO) is difficult because of its complex shape. Real-time 3-dimensional echocardiography (RT3DECHO) may be superior.

METHODS

End-diastolic volume, end-systolic volume, stroke volume, and ejection fraction obtained by 2DECHO, RT3DECHO short-axis disk summation (DS), and RT3DECHO apical rotation were compared with cardiac magnetic resonance imaging in 71 healthy individuals.

RESULTS

RT3DECHO DS showed less volume underestimation compared with 2DECHO and RT3DECHO apical rotation. Test-retest variability for RT3DECHO DS end-diastolic volume, end-systolic volume, stroke volume, and ejection fraction were 3.3%, 8.7%, 10%, and 10.3%, respectively. Normal reference ranges of indexed volumes (mean +/- 2SD) for right ventricular end-diastolic volume, end-systolic volume, stroke volume, and ejection fraction were 38.6 to 92.2 mL/m(2), 7.8 to 50.6 mL/m(2), 22.5 to 42.9 mL/m(2), and 38.0% to 65.3%, respectively, for women and 47.0 to 100 mL/m(2), 23.0 to 52.6 mL/m(2), 14.2 to 48.4 mL/m(2), and 29.9% to 58.4%, respectively, for men.

CONCLUSIONS

RT3DECHO DS is superior to RT3DECHO apical rotation and 2DECHO for right ventricular quantification, and performs acceptably when compared with cardiac magnetic resonance imaging in healthy individuals.

Quantitation of Right Ventricular Volumes and Ejection Fraction by Three-Dimensional Echocardiography in Patients: Comparison with Magnetic Resonance Imaging and Radionuclide Ventriculography

Three-dimensional echocardiography (3DE) provides volumetric measurements without geometric assumptions. Volume-rendered 3DE has been shown to be accurate for the measurement of right ventricular (RV) volumes in vitro and in animal studies; however, few data are available regarding its accuracy in patients. This study examined the accuracy of 3DE for quantitation of RV volumes and ejection fraction (EF) in patients, compared to magnetic resonance imaging (MRI) and radionuclide ventriculography (RNV). Twenty patients underwent MRI, gated equilibrium RNV, and 3DE using rotational acquisition from both the transesophageal and transthoracic approaches. RV volumes and EF were calculated from the 3DE data using multislice analysis (true Simpson's rule). RV volumes calculated by MRI (end-diastolic volume (EDV) 109.4 +/- 34.3 mls, end-systolic volume (ESV) 59.6 +/- 31.0 mls, and EF 47.7 +/- 17.1%) agreed closely with 3DE. For transesophageal echocardiography, EDV was 108.1 +/- 29.7 mls (r = 0.86, mean difference 1.3 +/- 17.8 mls); ESV was 62.5 +/- 23.8 mls (r = 0.85, mean difference 2.8 +/- 15.1 mls); and EF was 43.2 +/- 11.7% (r = 0.84, mean difference 4.5 +/- 9.7%). For transthoracic echocardiography, EDV was 107.7 +/- 27.5 mls (r = 0.85, mean difference 1.6 +/- 18.2 mls); ESV was 59.7 +/- 22.1 mls (r = 0.93, mean difference 3.2 +/- 19.6 mls); and EF was 45.2 +/- 11.5% (r = 0.86, mean difference 2.0 +/- 9.4%). There were close correlations, small mean differences and narrow limits of agreement between RNV-derived EF (43.4 +/- 12.1%) and both transesophageal (r = 0.95 mean difference 0.2 +/- 3.7%) and transthoracic 3DE (r = 0.95, mean difference 1.8 +/- 5.4%). Three-dimensional echocardiography is a promising new method of calculating RV volumes and EF, comparing well with MRI and RNV. The accuracy of transthoracic 3DE was comparable to that of the transesophageal approach. Three-dimensional echocardiography has the potential to be useful in the clinical assessment of RV disorders.

Three-dimensional echocardiography: research toy or clinical tool?

Conventional 2D echocardiography is an excellent qualitative imaging method, but its use for quantitation is limited by test-retest reproducibility of image planes. The increasing sophistication of medical treatments for left ventricular dysfunction, hypertension and valvular heart disease has created the need for accurate and reproducible measurements of chamber dimensions. Similarly, improvements in valve repair and catheter-based interventions for valve lesions and septal defects have created the need for better visualisation of cardiac structures. The use of 31) echocardiography may decrease variability both in the quality and interpretation of complex pathology among investigators. Three-dimensional echocardiography is achieved by using a 3D spatial registration device with a conventional 21) scanner, or by using a high-speed, phased-array real-time scanner. The latter are still developmental, so that the technique currently requires use of a 21) scanner, combined with a 31) spatial coordinate system, which may be external or internal to the scanning transducer. An external system permits data acquired from several cardiac windows to be integrated and reconstructed. Image reconstruction is performed using a wire-frame model or surface rendering. Wire-frame models are formed by manual or automatic connection of boundary data points; this approach uses fewer data points than rendering, can be rapidly processed and is sufficient for quantitative analysis. Surface-rendering uses lighting and shading applied to a wire-frame model to produce a realistic 31) display, which may be useful for surgical planning and increasing understanding of anatomic relations. Three-dimensional echocardiography yields more accurate measurements of ventricular volume and function, as well as new measurements such as infarct area. With increased reproducibility and reliability, 3D echocardiography may well prove to be the essential tool required for the serial follow up of left ventricular mass and volume.

Interstudy reproducibility of right ventricular volumes, function, and mass with cardiovascular magnetic resonance

BACKGROUND

Cardiovascular magnetic resonance (CMR) has shown excellent results for interstudy reproducibility in the assessment of left ventricular (LV) parameters. However, interstudy reproducibility data for the more complex-shaped right ventricle in a large study group have not yet been reported. We sought to determine the interstudy reproducibility of measurements of right ventricular (RV) volumes, function, and mass with CMR and compare it with correspondent LV values.

METHODS

Sixty subjects (47 men; 20 healthy volunteers, 20 patients with heart failure, 20 patients with ventricular hypertrophy) underwent 2 CMR studies for assessment of RV measurements with a minimum time interval between each study.

RESULTS

The overall interstudy reproducibility (range between groups) for the RV was 6.2% (4.2%-7.8%) for end-diastolic volume, 14.1% (8.1%-18.1%) for end-systolic volume, 8.3% (4.3%-10.4%) for ejection fraction (EF), and 8.7% (7.8%-9.4%) for RV mass. RV reproducibility was not as good as for the LV for all measures in all 3 groups, but this was only statistically significant for EF (P <.01).

CONCLUSIONS

CMR showed good interstudy reproducibility for RV function parameters in healthy subjects, patients with heart failure, and patients with hypertrophy, which suggests that CMR is reliable for serial RV assessment. These data can be used to power sample sizes for longitudinal research studies of RV volume and function. The reproducibility values were similar to, but generally lower than, the reproducibility values for the LV in the same study population, which indicates that sample sizes for RV studies are in general larger than those for LV studies.

Real-Time Three-Dimensional Echocardiography Using a Novel Matrix Array Transducer

Three-dimensional echocardiography has multiple advantages over two-dimensional echocardiography, such as accurate left ventricular quantification and improved spatial relationships. However, clinical use of three-dimensional echocardiography has been impeded by tedious and time-consuming methods for data acquisition and post-processing. A newly developed matrix array probe, which allows real-time three-dimensional imaging with instantaneous on-line volume-rendered reconstruction, direct manipulation of thresholding, and cut planes on the ultrasound unit may overcome the aforementioned limitations. This report will review current methods of three-dimensional data acquisition, emphasizing the real-time methods and clinical applications of the new matrix array probe.