Validation of real-time three-dimensional echocardiography for quantifying left ventricular volumes in the presence of a left ventricular aneurysm: in vitro and in vivo studies

Association of outcome with left ventricular volumes and ejection fraction measured with two- and three-dimensional echocardiography in patients referred for routine, clinically indicated studies

Objectives

We sought to analyze if left ventricular (LV) volumes and ejection fraction (EF) measured by three-dimensional echocardiography (3DE) have incremental prognostic value over measurements obtained from two-dimensional echocardiography (2DE) in patients referred to a high-volume echocardiography laboratory for routine, clinically-indicated studies.

Methods

We measured LV volumes and EF using both 2DE and 3DE in 725 consecutive patients (67% men; 59 ± 18 years) with various clinical indications referred for a routine clinical study.

Results

LV volumes were significantly larger, and EF was lower when measured by 3DE than 2DE. During follow-up (3.6 ± 1.2 years), 111 (15.3%) all-cause deaths and 248 (34.2%) cardiac hospitalizations occurred. Larger LV volumes and lower EF were associated with worse outcome independent of age, creatinine, hemoglobin, atrial fibrillation, and ischemic heart diseases). In stepwise Cox regression analyses, the associations of both death and cardiac hospitalization with clinical data (CD: age, creatinine, hemoglobin, atrial fibrillation, and ischemic heart disease) whose Harrel's C-index (HC) was 0.775, were augmented more by the LV volumes and EF obtained by 3DE than by 2DE parameters. The association of CD with death was not affected by LV end-diastolic volume (EDV) either measured by 2DE or 3DE. Conversely, it was incremented by 3DE LVEF (HC = 0.84, p < 0.001) more than 2DE LVEF (HC = 0.814, p < 0.001). The association of CD with the composite endpoint (HC = 0.64, p = 0.002) was augmented more by 3DE LV EDV (HC = 0.786, p < 0.001), end-systolic volume (HC = 0.801, p < 0.001), and EF (HC = 0.84, p < 0.001) than by the correspondent 2DE parameters (HC = 0.786, HC = 0.796, and 0.84, all p < 0.001) In addition, partition values for mild, moderate and severe reduction of the LVEF measured by 3DE showed a higher discriminative power than those measured by 2DE for cardiac death (Log-Rank: χ² = 98.3 vs. χ² = 77.1; p < 0.001). Finally, LV dilation defined according to the 3DE threshold values showed higher discriminatory power and prognostic value for death than when using 2DE reference values (3DE LVEDV: χ² = 15.9, p < 0.001 vs. χ² = 10.8, p = 0.001; 3DE LVESV: χ² = 24.4, p < 0.001 vs. χ² = 17.4, p = 0.001).

Conclusion

In patients who underwent routine, clinically-indicated echocardiography, 3DE LVEF and ESV showed stronger association with outcome than the corresponding 2DE parameters.

Incidental discovery of a rare right ventricular aneurysm

Three types of cardiac outpouchings are encountered on cardiovascular imaging: diverticula, aneurysms and pseudoaneurysms. The underlying physiology, imaging findings, risk of rupture, and optimal treatment varies for each and a correct diagnosis is critical. We report a case of a rare, incidentally discovered right ventricular aneurysm that was characterized by transthoracic echocardiogram, computed tomography, and cardiac MRI. The types of cardiac outpouchings are reviewed, and we discuss the selection of imaging modality, keys to distinguishing the outpouchings, and management strategies.

Left Ventricular End Diastolic Volume and Ejection Fraction Calculation: Correlation between Three Echocardiographic Methods

Background

Left ventricular ejection fraction (LVEF) and end diastolic volume (EDV) are measured using Simpson's biplane (SB), 3-dimensional method (3DE), and speckle tracking (STE). Comparisons between methods in routine practice are limited. Our purpose was to compare and to determine the correlations between these three methods in clinical setting.

Methods

LVEF and EDV were measured by three methods in 474 consecutive patients and compared using multiple Bland–Altman (BA) plots. The correlations (R) between methods were calculated.

Results

Median (IQR) LVEF_SB, LVEF_STE, and LVEF_3DE were 63.0% (60–69)%, 61% (57–65)%, and 62% (57–68)%. Median (IQR) EDV_SB, EDV_STE, and EDV_3DE were 85 ml (71–106) ml, 82 ml (69–100) ml, and 73 ml (59–89) ml. R between LVEF_SB and LVEF_3DE was 0.65 when echogenicity was good and 0.43 when poor. R for EDV_SB and EDV_3DE was 0.75 when echogenicity was good and 0.45 when poor. On BA analysis, biases were acceptable (<3.5% for LVEF) but limits of agreement (LOA) were large: 95% of the differences were between −15.4% and +18.8% for LVEF as evaluated by SB in comparison with 3DE, with a bias of 1.7%. In the comparison EDV_SB and EDV_3DE, the bias was 14 ml and the LOA were between −24 ml and +53 ml. On linear regressions, LVEF_3DE = 17.92 + 0.69 LVEF_SB and EDV_3DE = 18.94 + 0.63 EDV_SB.

Conclusions

The three methods were feasible and led to acceptable bias but large LOA. Although these methods are not interchangeable, our results allow 3DE value prediction from SB, the most commonly used method.

Three-dimensional echocardiography to assess left ventricular geometry and function

Introduction: Quantification of left ventricular (LV) size and function represents the most frequent indication for an echocardiographic study. New echocardiographic techniques have been developed over the last decades in an attempt to provide a more comprehensive, accurate, and reproducible assessment of LV function.Areas covered: Although two-dimensional echocardiography (2DE) is the recommended imaging modality to evaluate the LV, three-dimensional echocardiography (3DE) has proven to be more accurate, by avoiding geometric assumptions about LV geometry, and to have incremental value for outcome prediction in comparison to conventional 2DE. LV shape (sphericity) and mass are actually measured with 3DE. Myocardial deformation analysis using 3DE can early detect subclinical LV dysfunction, before any detectable change in LV ejection fraction.Expert opinion: 3DE eliminates the errors associated with foreshortening and geometric assumptions inherent to 2DE and 3DE measurements approach very closely those obtained by CMR (the current reference modality), while maintaining the unique clinical advantage of a safe, highly cost/effective, portable imaging technique, available to the cardiologist at bedside to translate immediately the echocardiography findings into the clinical decision-making process.

Right Ventricular Analysis Using Real-time Three-dimensional Echocardiography for Preload Dependency

BACKGROUND

The importance of the right ventricle (RV) has been increasingly recognized, and accurate RV measurement has become necessary. However, assessment of the RV with two-dimensional (2D) echocardiography has several limitations. As the development of novel methods for RV measurement continues, we can expect more accordant values related to RV geometry.

METHODS

Fifty-eight subjects who were examined by transthoracic echocardiography (TTE) immediately before and after hemodialysis (HD) were enrolled. Real-time, full-volume, three-dimensional (3D) echocardiographic images were acquired and analyzed using dedicated software. Conventional RV parameters for RV size and function were measured for comparison with pre-HD and post-HD values by both 2D-TTE and 3D-TTE.

RESULTS

3D RV volumes and ejection fractions were significantly decreased after HD. The values of the 3D image-derived RV dimensions, tricuspid annular plane systolic excursion (TAPSE), fractional area change (FAC), and longitudinal strain were also affected by acute preload changes (TAPSE pre-HD: 22.4 ± 4.0 mm, post-HD: 19.0 ± 4.2 mm, p < 0.001; FAC pre-HD: 49.6% ± 5.9%, post-HD: 46.4% ± 5.5%, p < 0.001; septal longitudinal strain pre-HD: -20.1% ± 3.7%, post-HD: -16.8% ± 3.8%, p < 0.001). With the exception of FAC, most 2D RV parameters were well correlated with the 3D values.

CONCLUSIONS

Various parameters representing RV anatomy and function were acquired easily and more accurately from 3D echocardiographic images than from 2D images but were affected by acute preload changes. 3D TTE could be a new modality for assessing RV function and size, but each value from 3D TTE should be interpreted with caution while considering the loading condition of the patients.

The impact of preload on 3-dimensional deformation parameters: principal strain, twist and torsion

Background

Strain analysis is feasible using three-dimensional (3D) echocardiography. This approach provides various parameters based on speckle tracking analysis from one full-volume image of the left ventricle; however, evidence for its volume independence is still lacking.

Methods

Fifty-eight subjects who were examined by transthoracic echocardiography immediately before and after hemodialysis (HD) were enrolled. Real-time full-volume 3D echocardiographic images were acquired and analyzed using dedicated software. Two-dimensional (2D) longitudinal strain (LS) was also measured for comparison with 3D strain values.

Results

Longitudinal (pre-HD: −24.57 ± 2.51, post-HD: −21.42 ± 2.15, P < 0.001); circumferential (pre-HD: −33.35 ± 3.50, post-HD: −30.90 ± 3.22, P < 0.001); and radial strain (pre-HD: 46.47 ± 4.27, post-HD: 42.90 ± 3.61, P < 0.001) values were significantly decreased after HD. The values of 3D principal strain (PS), a unique parameter of 3D images, were affected by acute preload changes (pre-HD: −38.10 ± 3.71, post-HD: −35.33 ± 3.22, P < 0.001). Twist and torsion values were decreased after HD (pre-HD: 17.69 ± 7.80, post-HD: 13.34 ± 6.92, P < 0.001; and pre-HD: 2.04 ± 0.86, post-HD:1.59 ± 0.80, respectively, P < 0.001). The 2D LS values correlated with the 3D LS and PS values.

Conclusion

Various parameters representing left ventricular mechanics were easily acquired from 3D echocardiographic images; however, like conventional parameters, they were affected by acute preload changes. Therefore, strain values from 3D echocardiography should be interpreted with caution while considering the preload conditions of the patients.

Real-Time Three-Dimensional Echocardiography: Characterization of Cardiac Anatomy and Function-Current Clinical Applications and Literature Review Update

Our review of real-time three-dimensional echocardiography (RT3DE) discusses the diagnostic utility of RT3DE and provides a comparison with two-dimensional echocardiography (2DE) in clinical cardiology. A Pubmed literature search on RT3DE was performed using the following key words: transthoracic, two-dimensional, three-dimensional, real-time, and left ventricular (LV) function. Articles included perspective clinical studies and meta-analyses in the English language, and focused on the role of RT3DE in human subjects. Application of RT3DE includes analysis of the pericardium, right ventricular (RV) and LV cavities, wall motion, valvular disease, great vessels, congenital anomalies, and traumatic injury, such as myocardial contusion. RT3DE, through a transthoracic echocardiography (TTE), allows for increasingly accurate volume and valve motion assessment, estimated LV ejection fraction, and volume measurements. Chamber motion and LV mass approximation have been more accurately evaluated by RT3DE by improved inclusion of the third dimension and quantification of volumetric movement. Moreover, RT3DE was shown to have no statistical significance when comparing the ejection fractions of RT3DE to cardiac magnetic resonance (CMR). Analysis of RT3DE data sets of the LV endocardial exterior allows for the volume to be directly quantified for specific phases of the cardiac cycle, ranging from end systole to end diastole, eliminating error from wall motion abnormalities and asymmetrical left ventricles. RT3DE through TTE measures cardiac function with superior diagnostic accuracy in predicting LV mass, systolic function, along with LV and RV volume when compared with 2DE with comparable results to CMR.

Role of cardiac CTA in estimating left ventricular volumes and ejection fraction

Left ventricular ejection fraction (LVEF) is an important predictor of cardiac outcome and helps in making important diagnostic and therapeutic decisions such as the treatment of different types of congestive heart failure or implantation of devices like cardiac resynchronization therapy-defibrillator. LVEF can be measured by various techniques such as transthoracic echocardiography, contrast ventriculography, radionuclide techniques, cardiac magnetic resonance imaging and cardiac computed tomographic angiography (CTA). The development of cardiac CTA using multi-detector row CT (MDCT) has seen a very rapid improvement in the technology for identifying coronary artery stenosis and coronary artery disease in the last decade. During the acquisition, processing and analysis of data to study coronary anatomy, MDCT provides a unique opportunity to measure left ventricular volumes and LVEF simultaneously with the same data set without the need for additional contrast or radiation exposure. The development of semi-automated and automated software to measure LVEF has now added uniformity, efficiency and reproducibility of practical value in clinical practice rather than just being a research tool. This article will address the feasibility, the accuracy and the limitations of MDCT in measuring LVEF.

Left ventricular apical aneurysm in chronic Chagas cardiomyopathy-A case report

A 56-year-old female, who immigrated to the USA from Honduras, presented with worsening shortness of breath, orthopnea, paroxysmal nocturnal dyspnea, and decreased exercise tolerance over the previous 2 months. She was diagnosed 1 year previously with non-ischemic dilated cardiomyopathy and non-sustained monomorphic ventricular tachycardia. An implantable cardioverter defibrillator was placed. Cause for her dilated cardiomyopathy was unknown at that time. On admission, her electrocardiogram showed low voltage complexes, with frequent premature ventricular contractions. Transthoracic two-dimensional echocardiogram (2D ECHO) showed severely reduced ejection fraction of 20%, severe mitral regurgitation with left ventricular (LV) hypokinesis, and inferolateral and inferior wall akinesis. On review of her records, a contrast 2D ECHO from the previous year revealed an aneurysm of the LV apical region. Live three-dimensional (3D) ECHO on her present admission showed persistent LV apical aneurysm. Computed tomography angiogram showed no atherosclerotic lesions. Multiple episodes of non-sustained ventricular tachycardia were recorded on telemetry. Based on these findings, the diagnosis of Chagas cardiomyopathy was entertained. Serological tests for Trypanosoma cruzi antibodies were done and returned positive. We report a case of chronic Chagas cardiomyopathy that was initially missed but ultimately diagnosed based on the finding of LV apical aneurysm. <Learning objective: Chagas cardiomyopathy is becoming increasingly prevalent in non-endemic countries. One hallmark finding associated with Chagas cardiomyopathy is left ventricle apical aneurysm. We were able to identify this finding with transthoracic contrast 2D ECHO and live 3D ECHO.>.

Quantitative assessment of primary mitral regurgitation using left ventricular volumes: a three-dimensional transthoracic echocardiographic pilot study

AIMS

To investigate the value of assessment of mitral regurgitant fraction (RF) using left ventricular (LV) volumes obtained by three-dimensional echocardiography (3DE) to quantify primary mitral regurgitation (MR).

METHODS AND RESULTS

Sixty patients with primary MR in sinus rhythm were prospectively enrolled. RF was calculated using either 2DE or 3DE LV volumes obtained as follows: (LV total stroke volume - LV forward stroke volume by Doppler)/LV total stroke volume. Severity of MR was graded independently by two cardiologists blinded to LV volumetric data using an integrative approach, as recommended by current guidelines. Sixty patients with LV ejection fraction >50% and no MR were also studied. In patients without MR, 3D total LV stroke volume was more strongly correlated with LV forward stroke volume than 2D total LV stroke volume (r = 0.75, P < 0.0001 vs. r = 0.62, P < 0.0001, respectively). The 3D method had a feasibility of 90% in patients with MR. Inter-reader concordance for MR grading (four grades) was excellent with a Kappa-value of 0.90, P < 0.0001. A significant correlation was observed between grade of MR severity and 3D RF (r = 0.83, P < 0.0001) and 2D RF (r = 0.74, P < 0.0001). Comparisons between individual grades for 3D RF were significant (P < 0.05) except for 3+ vs. 4+ MR (P = 0.213). All patients with 3D RF ≥40% had ≥3+ or 4+ MR and those with 3D RF ≤30% had 1+ or 2+ MR with a 'grey' overlap zone between 30 and 40%.

CONCLUSIONS

RF can be routinely determined using 3D LV volumes with a high feasibility in patients with primary MR and is reliable for identification of Grade 3+ or Grade 4+ MR. The incorporation of this parameter into the currently recommended multiparametric integrative approach might be helpful to discriminate significant MR.

The clinical benefits of adding a third dimension to assess the left ventricle with echocardiography

Three-dimensional echocardiography is a novel imaging technique based on acquisition and display of volumetric data sets in the beating heart. This permits a comprehensive evaluation of left ventricular (LV) anatomy and function from a single acquisition and expands the diagnostic possibilities of noninvasive cardiology. It provides the possibility of quantitating geometry and function of LV without preestablished assumptions regarding cardiac chamber shape and allows an echocardiographic assessment of the LV that is less operator-dependent and therefore more reproducible. Further developments and improvements for widespread routine applications include higher spatial and temporal resolution to improve image quality, faster acquisition, processing and reconstruction, and fully automated quantitative analysis. At present, three-dimensional echocardiography complements routine 2DE in clinical practice, overcoming some of its limitations and offering additional valuable information that has led to recommending its use for routine assessment of the LV of patients in whom information about LV size and function is critical for their clinical management.

Quantitative assessment of left ventricular systolic function using 3-dimensional echocardiography

Assessment of left ventricular systolic function is the commonest and one of the most important indications for performance of echocardiography. It is important for prognostication, determination of treatment plan, for decisions related to expensive device therapies and for assessing response to treatment. The current methods based on two-dimensional echocardiography are not reliable, have high degree of inter-observer and intra-observer variability and are based on presumptions about the geometry of left ventricle (LV). Real-time three-dimensional echocardiography (RT3DE) on the other hand is fast, easy, accurate, relatively operator independent and is not based on any assumptions related to the shape of LV. Owing to these advantages, it is the Echocardiographic modality of choice for assessment of systolic function of the LV. We describe here a step by step approach to evaluation of LV volumes, ejection fraction, regional systolic function and Dyssynchrony analysis based on RT3DE. It has been well validated in clinical studies and is rapidly being incorporated in routine clinical practice.

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.

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.

Head-to-head comparison of left ventricular function assessment with 64-row computed tomography, biplane left cineventriculography, and both 2- and 3-dimensional transthoracic echocardiography: comparison with magnetic resonance imaging as the reference standard

OBJECTIVES

This study was designed to compare the accuracy of 64-row contrast computed tomography (CT), invasive cineventriculography (CVG), 2-dimensional echocardiography (2D Echo), and 3-dimensional echocardiography (3D Echo) for left ventricular (LV) function assessment with magnetic resonance imaging (MRI).

BACKGROUND

Cardiac function is an important determinant of therapy and is a major predictor for long-term survival in patients with coronary artery disease. A number of methods are available for assessment of function, but there are limited data on the comparison between these multiple methods in the same patients.

METHODS

A total of 36 patients prospectively underwent 64-row CT, CVG, 2D Echo, 3D Echo, and MRI (as the reference standard). Global and regional LV wall motion and ejection fraction (EF) were measured. In addition, assessment of interobserver agreement was performed.

RESULTS

For the global EF, Bland-Altman analysis showed significantly higher agreement between CT and MRI (p < 0.005, 95% confidence interval: ±14.2%) than for CVG (±20.2%) and 3D Echo (±21.2%). Only CVG (59.5 ± 13.9%, p = 0.03) significantly overestimated EF in comparison with MRI (55.6 ± 16.0%). CT showed significantly better agreement for stroke volume than 2D Echo, 3D Echo, and CVG. In comparison with MRI, CVG-but not CT-significantly overestimated the end-diastolic volume (p < 0.001), whereas 2D Echo and 3D Echo significantly underestimated the EDV (p < 0.05). There was no significant difference in diagnostic accuracy (range: 76% to 88%) for regional LV function assessment between the 4 methods when compared with MRI. Interobserver agreement for EF showed high intraclass correlation for 64-row CT, MRI, 2D Echo, and 3D Echo (intraclass correlation coefficient >0.8), whereas agreement was lower for CVG (intraclass correlation coefficient = 0.58).

CONCLUSIONS

64-row CT may be more accurate than CVG, 2D Echo, and 3D Echo in comparison with MRI as the reference standard for assessment of global LV function.

Assessment of recanalization of chronic total occlusions on left ventricular function in patients with or without previous myocardial infarction by real-time three-dimensional echocardiography

The changes of left ventricular ejection fraction (LVEF) were assessed after successful recanalization of chronic total occlusions (CTO) with or without previous myocardial infarction (MI) by real-time three-dimensional echocardiography (RT3DE). 32 patients with a successfully recanalyzed CTO were included in the present prospective study. The patients were divided into group 1 without previous MI and group 2 with previous MI in the territories of total occlusion vessel that was recanalized. In addition, there was a subgroup composed of 14 patients with collateral flow or retrograde flow in group 2. In all patients, LVEF was determined by RT3DE at baseline and after 6 weeks. In group 1, the evolution of LVEF increased significantly from 59.9 ± 7.2-67.5 ± 8.7% (P < 0.05). In group 2, the evolution of LVEF increased from 48.6 ± 6.1-50.1 ± 6.4%, however, it was without statistic significance (P > 0.05). The evolution of LVEF increased from 46.8 ± 7.1-53.0 ± 7.2% (P < 0.05) in the subgroup of group 2. Left ventricular function in patients with CTO can be feasibility and actually evaluated by RT3DE. The influence of recanalization of CTO on the improvement of left ventricular function was different between MI and non-MI patients. The left ventricular function did not improve in MI patients, but improved significantly in the patients having rich collateral circulation.

Three-dimensional echocardiography for the preoperative assessment of patients with left ventricular aneurysm

BACKGROUND

Surgical ventricular reconstruction has been proposed as a treatment option in heart failure patients with left ventricular (LV) aneurysm. The feasibility of this procedure has some limitations, and extensive preoperative evaluation is necessary to give the correct indication. For this purpose, magnetic resonance imaging (MRI) is currently considered the gold standard, providing accurate quantification of LV shape, size, and global and regional function together with the assessment of myocardial scar and mitral regurgitation severity. The aim of this study was to evaluate the accuracy of real-time three-dimensional echocardiography (RT3DE) as a potential alternative to MRI for this evaluation.

METHODS

A total of 52 patients with ischemic cardiomyopathy and LV aneurysm underwent a comprehensive analysis with two-dimensional echocardiography, RT3DE, and MRI.

RESULTS

Excellent correlation (r=0.97, p<0.001) and agreement were found between RT3DE and MRI for quantification of LV volumes, ejection fraction, and sphericity index; in a segment-to-segment comparison, RT3DE was shown to be accurate also for the analysis of wall motion abnormalities (k=0.62) and LV regional thickness (k=0.56) as a marker of myocardial scar. In contrast, two-dimensional echocardiography significantly underestimated these variables. Furthermore, mitral regurgitant volume assessed by RT3DE showed excellent correlation (r=0.93) with regurgitant volume measured by MRI, without significant bias (=-0.7 mL/beat).

CONCLUSIONS

In the management of heart failure patients with LV aneurysm, RT3DE provides an accurate and comprehensive assessment, including quantification of LV size, shape, global systolic function, regional wall motion, and myocardial scar together with precise evaluation of the severity of mitral regurgitation.

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

[Evaluation of the left ventricle with three-dimensional echocardiography: comparison with cardiac magnetic resonance]

OBJECTIVE

Three-dimensional echocardiography (3DE) is becoming increasingly common in clinical environments. However, the quality of the images depends on the acoustic window, and it can be difficult to identify the endocardial borders. The objective of this study was to evaluate the performance of 3DE in determining the volumes and left ventricular ejection fraction in unselected patients against the gold standard, cardiac magnetic resonance (CMR).

MATERIAL AND METHODS

In 47 unselected patients who underwent CMR, we performed 3DE using a real-time acquisition technique and semiautomatic border detection.

RESULTS

We excluded 4 patients (8.5%) because they had an extremely deficient acoustic window. In the remaining 43 patients, including those with a suboptimal acoustic window, we obtained the following correlations between 3DE and CMR: end-diastolic volume, 0.71; end-systolic volume, 0.77; ejection fraction, 0.74. Although the end-diastolic volume was systematically underestimated, no significant differences were observed in the ejection fraction. When the 11 patients with suboptimal acoustic windows were excluded, we observed a systematic underestimation of the end-diastolic and end-systolic volumes, which paradoxically gave rise to improved correlation coefficients (0.79, 0.92, and 0.84, respectively) and a more accurate ejection fraction.

CONCLUSIONS

Compared to CMR, 3DE systematically underestimates the ventricular volumes but enables adequate determination of the left ventricular ejection fraction regardless of the quality of the acoustic window.

Gated blood-pool SPECT versus cardiac magnetic resonance imaging for the assessment of left ventricular volumes and ejection fraction

BACKGROUND

We evaluated the accuracy of planar radionuclide angiography and different count-based and space-based electrocardiogram (ECG)-gated blood-pool single-photon emission computed tomography (GBPS) algorithms for assessment of left ventricular end-diastolic volume (LVEDV), end-systolic volume (LVESV), and ejection fraction (LVEF) compared with the gold standard of cardiac magnetic resonance imaging (cMRI). The goal is to assess the accuracy of a recently developed GBPS algorithm.

METHODS AND RESULTS

Subjects had planar, GBPS, and cMRI sequentially. Datasets were processed by QBS software (Cedar-Sinai) and by MHI software (Montreal Heart Institute). Space-based approaches were used to compute LVEDV, LVESV, and LVEF. Count-based techniques were also used to assess LVEF. All results were compared to cMRI. Fifty-five patients (85% male; mean age 63 +/- 9 years) completed the study. LVEFs and their correlations to cMRI values were 43 +/- 12% (r = .82), 39 +/- 14% (r = .82), and 39 +/- 13% for MHI(space), QBS(space), and cMRI methodologies, respectively. LVEF by count-based methods also demonstrated good correlation to LVEF provided by cMRI (42 +/- 13%, r = .88 for MHI(count) and 46 +/- 15%, r = .84 for QBS(count)). Strong correlations were obtained for LVEDV (r = .96 for MHI and r = .92 for QBS) and for LVESV (.97 for MHI and r = .94 for QBS).

CONCLUSIONS

All Gated blood-pool SPECT algorithms had significant variation in estimating LVEF. Nevertheless our software provides good estimates of LV volumes and LVEF. Such software may, therefore, be applied to assess LV morphology and function.

Relation of plasma brain natriuretic peptide levels on admission for ST-elevation myocardial infarction to left ventricular end-diastolic volume six months later measured by both echocardiography and cardiac magnetic resonance

The main objective of this study was to investigate the relation between brain natriuretic peptide (BNP) levels within the first 96 hours after ST-segment elevation acute myocardial infarction (STEMI) and the development of left ventricular (LV) dilatation at 6-month follow-up. Eighty-two patients with first STEMIs, reperfused within 12 hours of symptom onset, were prospectively included. Plasma BNP was determined on admission and at 1- and 6-month follow-up. Clinically significant LV dilatation, defined as a >20% increase in LV end-diastolic volume at 6-month follow-up, was assessed using echocardiography and cardiac magnetic resonance. Thirty-two percent of patients developed clinically significant LV dilatation. BNP values on admission and at follow-up were significantly higher in patients who developed clinically significant LV dilatation at 6 months (182 +/- 117 vs 106 +/- 91 pmol/ml). After adjusting for age, infarct size, E-wave deceleration time, and the LV ejection fraction, BNP on admission was an independent predictor of LV dilatation, whether assessed by echocardiography (B = 0.075, p = 0.04) or cardiac magnetic resonance (B = 0.085, p = 0.04). In conclusion, high BNP levels on admission and at follow-up predict LV dilatation after STEMI. The early determination of plasma BNP upon admission for STEMI could be helpful in identifying patients at higher risk for LV dilatation, in whom aggressive management is warranted.

Real-time three-dimensional echocardiographic assessment of left ventricular remodeling index in patients with hypertensive heart disease and coronary artery disease

Left ventricular remodeling index (LVRI) was assessed in patients with hypertensive heart disease (HHD) and coronary artery disease (CAD) by real-time three-dimensional echocardiography (RT3DE). RT3DE data of 18 patients with HHD, 20 patients with CAD and 22 normal controls (NC) were acquired. Left ventricular end-diastolic volume (EDV) and left ventricular end-diastolic epicardial volume (EDVepi ) were detected by RT3DE and two-dimensional echocardiography Simpson biplane method (2DE). LVRI (left ventricular mass /EDV) was calculated and compared. The results showed that LVRI measurements detected by RT3DE and 2DE showed significant differences inter-groups (P<0.01). There was no significant difference in NC group (P>0.05), but significant difference in HHD and CAD intra-group (P<0.05). There was good positive correlations between LVRI detected by RT3DE and 2DE in NC and HHD groups (r=0.69, P<0.01; r=0.68, P<0.01), but no significant correlation in CAD group (r=0.30, P>0.05). It was concluded that LVRI derived from RT3DE as a new index for evaluating left ventricular remodeling can provide more superiority to LVRI derived from 2DE.

Relative importance of errors in left ventricular quantitation by two-dimensional echocardiography: insights from three-dimensional echocardiography and cardiac magnetic resonance imaging

BACKGROUND

The accuracy of left ventricular (LV) volumes and ejection fraction (EF) on two-dimensional echocardiography (2DE) is limited by image position (IP), geometric assumption (GA), and boundary tracing (BT) errors.

METHODS

Real-time three-dimensional echocardiography (RT3DE) and cardiac magnetic resonance imaging (CMR) were used to determine the relative contribution of each error source in normal controls (n = 35) and patients with myocardial infarctions (MIs) (n = 34). LV volumes and EFs were calculated using (1) apical biplane disk summation on 2DE (IP + GA + BT errors), (2) biplane disk summation on RT3DE (GA + BT errors), (3) 4-multiplane to 8-multiplane surface approximation on RT3DE (GA + BT errors), (4) voxel-based surface approximation on RT3DE (BT error alone) and (5) CMR. By comparing each method with CMR, the absolute and relative contributions of each error source were determined.

RESULTS

IP error predominated in LV volume quantification on 2DE in normal controls, whereas GA error predominated in patients with MIs. Underestimation of volumes on 2DE was overcome by increasing the number of imaging planes on RT3DE. Although 4 equidistant image planes were acceptable, the best results were achieved with voxel-based RT3DE. For EF estimation, IP error predominated in normal controls, whereas BT error predominated in patients with MIs. Nevertheless, one third of the EF estimation error in patients with MIs was due to a combination of IP and GA errors, both of which may be addressed using RT3DE.

CONCLUSIONS

The relative contribution of each source of LV quantitation error on 2DE was defined and quantified. Each source of error differed depending on patient characteristics and LV geometry.

Comparison of cardiac function and coronary angiography between conventional pigs and micropigs as measured by multidetector row computed tomography

Pigs are the most likely source animals for cardiac xenotransplantation. However, an appropriate method for estimating the cardiac function of micropigs had not been established. Computed tomography (CT) analysis aimed at estimating cardiac function and assessing the coronary arteries has not been carried out in micropigs. This study determined the feasibility of evaluating cardiac function in a micropig model using multidetector row computed tomography (MDCT) and compared the cardiac function values with those of conventional pigs. The mean age of the conventional pigs and micropigs was approximately 80 days and approximately 360 days, respectively. The mean body weight in the conventional pigs and micropigs was 29.70 ± 0.73 and 34.10 ± 0.98 kg, respectively. Cardiac MDCT detected ejection fractions of 52.93 ± 3.10% and 59.00 ± 5.56% and cardiac outputs of 1.46 ± 0.64 l/min and 1.21 ± 0.24 l/min in conventional pigs and micropigs, respectively. There were no significant differences in cardiac function between conventional pigs and micropigs in the reconstructed CT images. There were also no differences in the coronary angiographic images obtained by MDCT. It is expected that the results of this study will help improve understanding of cardiac function in micropigs. The data presented in this study suggest that MDCT is a feasible method for evaluating cardiac function in micropigs.

Three-dimensional adult echocardiography: where the hidden dimension helps

The introduction of three-dimensional (3D) imaging and its evolution from slow and labor-intense off-line reconstruction to real-time volumetric imaging is one of the most significant developments in ultrasound imaging of the heart of the past decade. This imaging modality currently provides valuable clinical information that empowers echocardiography with new levels of confidence in diagnosing heart disease. One major advantage of seeing the additional dimension is the improvement in the accuracy of the evaluation of cardiac chamber volumes by eliminating geometric modeling and the errors caused by foreshortened views. Another benefit of 3D imaging is the realistic views of cardiac valves capable of demonstrating numerous pathologies in a unique, noninvasive manner. This article reviews the major technological developments in 3D echocardiography and some of the recent literature that has provided the scientific basis for its clinical use.

Real-time three-dimensional echocardiography in aortic stenosis: a novel, simple, and reliable method to improve accuracy in area calculation

AIMS

The aim of the study was to validate a novel formula for aortic area, based on the principle of continuity equation (CE), that substitutes Doppler-derived stroke volume (SV) by SV directly measured with real-time three-dimensional (RT3D) echo and semi-automated border detection. RT3D has proved outstanding accuracy for left ventricular volume calculation. So far, however, neither this potential has been applied to haemodynamic assessment, nor RT3D has succeeded in the evaluation of aortic valve disease.

METHODS AND RESULTS

Aortic area was measured in 41 patients with aortic stenosis using Gorlin's equation, Hakki's formula, Doppler CE, two-dimensional Simpson's volumetric method, and by the novel RT3D method. RT3D has the best linear association and absolute agreement with Gorlin of all non-invasive methods r = 0.902, intraclass correlation coefficient (ICC) = 0.846, better than CE (r = 0.646, ICC = 0.626) and two-dimensional volumetric method (r = 0.627, ICC = 0.378). Linear and Passing-Bablok regression show that RT3D fits better to Gorlin (r(2) = 0.814) than CE (r(2) = 0.417) and two-dimensional method (r(2) = 0.393). Its accuracy is comparable to Hakki's formula, routinely employed in catheter laboratories. Inter- and intraobserver agreements (ICC) were, respectively, 0.732 and 0.985, better than CE (0.662, 0.857). RT3D also grades most efficiently the severity of aortic stenosis as mild, moderate, or severe (weighted kappa = 0.932). RT3D underestimates aortic area (95% CI 0.084-0.193). ROC curves, however, show that the optimal cutoff point to consider aortic stenosis severity remains close to 1 cm(2) (1.06 cm(2)).

CONCLUSIONS

RT3D is more accurate than CE and than two-dimensional volumetric methods to calculate area and to grade the severity of aortic stenosis. Area obtained by three-dimensional echo is slightly underestimated, but its range is clinically negligible.

Evaluation of Left Ventricular Contractile Function Using Noninvasively Determined Single-beat End-systolic Elastance in Mitral Regurgitation: Experimental Validation and Clinical Application

OBJECTIVE

We performed this study to validate the single-beat estimation of end-systolic elastance (E(es)) in an animal model of chronic mitral regurgitation (MR) and to use E(es) to predict postoperative left ventricular (LV) systolic function with the noninvasively derived single-beat E(es) (E(es-s)) in patients with MR.

METHODS

Eight sheep with MR were studied under 4 different loading conditions. E(es) was measured as the slope of the end-systolic pressure-volume relationship with a conductance catheter during inferior vena cava occlusion. E(es-s) was calculated using a bilinearly approximated time-varying elastance curve. We also studied 105 patients with MR who had undergone mitral valve repair. All measurements in these patients were performed before surgery and repeated at about 1 week after surgery.

RESULTS

In the animals in a total of 23 different stages, E(es-s) showed a good correlation and agreement with invasively determined E(es) (y = 0.84 x + 0.38; r = 0.8; P < .01, mean difference = 0.1 +/- 0.6 mm Hg/mL). In the clinical study, preoperative E(es-s) (r = 0.77; P < .001) and end-systolic volume index correlated well with postoperative ejection fraction (r = -0.69; P < .001). Multivariate analyses revealed that only E(es-s) was an independent predictor of postoperative LV function. Preoperative E(es-s) less than or equal to 1.0 mm Hg/mL was most predictive for identifying patients with LV dysfunction after surgery (sensitivity 87%; specificity 76%).

CONCLUSIONS

LV end-systolic elastance can be estimated noninvasively and is useful to detect latent LV dysfunction in patients with MR before surgery.

Aortic regurgitation: assessment with 64-section CT

PURPOSE

To prospectively evaluate diagnostic accuracy of 64-section computed tomography (CT) for evaluation of aortic regurgitation (AR), with transthoracic echocardiography (TTE) as reference.

MATERIALS AND METHODS

The institutional review board approved this study; written informed consent was obtained. Thirty patients (23 men, seven women; mean age, 56.6 years) with AR underwent TTE and retrospective electrocardiographically gated 64-section CT. CT data sets were reconstructed in 5% steps from 40% to 90% of R-R interval for analysis. Maximum regurgitant orifice area (ROA) in diastole was planimetrically measured with CT, and measurements were compared with semiquantitative classification with TTE (Spearman rank order correlation coefficients). Receiver operating characteristic (ROC) curves were calculated for differentiation between degrees of AR with ROA measurements. Dimensions of the aortic root and left ventricular parameters were compared (Pearson correlation analysis).

RESULTS

A significant correlation was observed between CT planimetric size of ROA (mean, 62 mm2+/-63 [standard deviation]; range, 6-224 mm2) and TTE classification of mild, moderate, and severe AR (r=0.84, P<.001). With ROC analysis, discrimination between degrees of AR with CT was highly accurate when cutoff ROAs (25 mm2 and 75 mm2) were used. A significant correlation was observed between methods in dimensions of aortic annulus (mean, 29.0 mm+/-4.6), sinus of Valsalva (mean, 38.3 mm+/-8.6), and ascending aorta (mean, 37.2 mm+/-8.0); mean values were 27.4 mm+/-4.9 (r=0.76, P<.001), 37.7 mm+/-8.6 (r=0.94, P<.001), and 38.2 mm+/-7.9 (r=0.96, P<.001), respectively. Mean end-systolic volume (67 mL+/-38), end-diastolic volume (149 mL+/-48), and ejection fraction (57%+/-13) at CT correlated well with mean results at TTE (65 mL+/-36 [r=0.96, P<.001], 140 mL+/-48 [r=0.91, P<.001], 56%+/-13 [r=0.98, P<.001], respectively).

CONCLUSION

Results of assessment of AR with 64-section CT are similar to those with TTE.