Imaging the forgotten chamber: is the devil in the boundary?

Forgotten No More-The Role of Right Ventricular Dysfunction in Heart Failure with Reduced Ejection Fraction: An Echocardiographic Perspective

During the last decade, studies have raised awareness of the crucial role that the right ventricle plays in various clinical settings, including diseases primarily linked to the left ventricle. The assessment of right ventricular performance with conventional echocardiography is challenging. Novel echocardiographic techniques improve the functional assessment of the right ventricle and they show good correlation with the gold standard represented by cardiac magnetic resonance. This review summarizes the traditional and innovative echocardiographic techniques used in the functional assessment of the right ventricle, focusing on the role of right ventricular dysfunction in heart failure with reduced ejection fraction and providing a perspective on recent evidence from literature.

Right Ventricular Dysfunction and Short-Term Outcomes Following Left-Sided Valvular Surgery: An Echocardiographic Study

Background The prognostic value of echocardiographic evaluation of right ventricular (RV) function in patients undergoing left-sided valvular surgery has not been well described. The objective of this study is to determine the role of broad echocardiographic assessment of RV function in predicting short-term outcomes after valvular surgery. Methods and Results Preoperative echocardiographic data, perioperative adverse outcomes, and 30-day mortality were analyzed in patients who underwent left-sided valvular surgery from 2006 to 2014. Echocardiographic parameters used to evaluate RV function include RV fractional area change, tricuspid annular plane systolic excursion, systolic movement of the RV lateral wall using tissue Doppler imaging (S'), RV myocardial performance index, and RV dP/dt. Subjects with at least 3 abnormal parameters out of the 5 aforementioned indices were defined as having significant RV dysfunction. The study included 269 patients with valvular surgery (average age: 67±15, 60.6% male, 148 aortic, and 121 mitral). RV dysfunction was found in 53 (19.7%) patients; 30-day mortality occurred in 20 patients (7.5%). Compared with normal RV function, patients with RV dysfunction had higher 30-day mortality (22.6% versus 3.8%; P=0.01) and were at risk for developing multisystem failure/shock (13.2% versus 3.2%; P=0.01). Multivariate analyses showed that preexisting RV dysfunction was the strongest predictor of increased 30-day mortality (odds ratio: 3.5; 95% CI, 1.1-11.1; P<0.05). Conclusions Preoperative RV dysfunction identified by comprehensive echocardiographic assessment is a strong predictor of adverse outcomes following left-sided valvular surgery.

Comprehensive Assessment of Right Ventricular Function by Three-Dimensional Speckle-Tracking Echocardiography: Comparisons with Cardiac Magnetic Resonance Imaging

BACKGROUND

Three-dimensional speckle-tracking echocardiography (3D-STE) has been increasingly used to quantify right ventricular (RV) function. However, direct comparisons of 3D-STE with cardiac magnetic resonance (CMR) imaging for evaluation of RV function are limited. This study aimed to test the feasibility and accuracy of 3D-STE for the quantification of RV volumes, ejection fraction (EF), and longitudinal strain in comparison with CMR imaging and to determine whether 3D-STE for RV strain is superior to two-dimensional (2D) STE in comparison with CMR imaging.

METHODS

A total of 195 consecutive patients referred for both CMR imaging and echocardiography were studied. Right ventricular end-diastolic volume (RVEDV), RV end-systolic volume (RVESV), RVEF, and 3D RV longitudinal strain (3D-RVLS) of the free wall by 3D-STE and 2D-RVLS of the free wall by 2D-STE, were compared with CMR measurements. Pearson correlation and Bland-Altman analyses were used to assess the intertechnique agreement.

RESULTS

Right ventricular 3D-STE was feasible in 174 patients (89%). Right ventricular volumes and EF determined by 3D-STE strongly correlated with CMR values (RVEDV, r = 0.94; RVESV, r = 0.96; RVEF, r = 0.91; all P < .001). Three-dimensional STE slightly underestimated the RV volumes and longitudinal strain and overestimated the RVEF. The 3D-RVLS values correlated better than 2D-RVLS values with CMR values (0.85 vs 0.64, P < .001) with smaller bias and narrower limits of agreement (bias: 2.0 and 2.6; limits of agreement: 8.5 and 12.5, respectively). The bias and limits of agreement for 3D-STE-obtained RVLS were increased in patients with RV dilation, RVEF < 45%, or lower frame rate compared with those with normal RV size, RVEF ≥ 45%, or higher frame rate, respectively. Right ventricular 3D-STE measurements were highly reproducible.

CONCLUSIONS

The 3D-STE measurements of RV volumes, EF, and longitudinal strain are highly feasible and reproducible, and data measured by 3D-STE correlate strongly with those determined using CMR imaging. Thus, 3D-STE may be a valid alternative to CMR imaging for the quantification of RV function in everyday clinical practice.

Echocardiographic assessment of the right heart in adults: a practical guideline from the British Society of Echocardiography

The structure and function of the right side of the heart is influenced by a wide range of physiological and pathological conditions. Quantification of right heart parameters is important in a variety of clinical scenarios including diagnosis, prognostication, and monitoring response to therapy. Although echocardiography remains the first-line imaging investigation for right heart assessment, published guidance is relatively sparse in comparison to that for the left ventricle. This guideline document from the British Society of Echocardiography describes the principles and practical aspects of right heart assessment by echocardiography, including quantification of chamber dimensions and function, as well as assessment of valvular function. While cut-off values for normality are included, a disease-oriented approach is advocated due to the considerable heterogeneity of structural and functional changes seen across the spectrum of diseases affecting the right heart. The complex anatomy of the right ventricle requires special considerations and echocardiographic techniques, which are set out in this document. The clinical relevance of right ventricular diastolic function is introduced, with practical guidance for its assessment. Finally, the relatively novel techniques of three-dimensional right ventricular echocardiography and right ventricular speckle tracking imaging are described. Despite these techniques holding considerable promise, issues relating to reproducibility and inter-vendor variation have limited their clinical utility to date.

Knowledge-based reconstruction of right ventricular volumes using real-time three-dimensional echocardiographic as well as cardiac magnetic resonance images: comparison with a cardiac magnetic resonance standard

BACKGROUND

Right ventricular volume quantification using real-time three-dimensional echocardiographic (RT3DE) imaging is limited by technical shortcomings of acquisition and quantification. In this study, a two-step approach was used to overcome these limitations. First, a modified acquisition technique for RT3DE imaging was applied, and second, a software tool using knowledge-based reconstruction (KBR) was used. The approach was validated against the gold standard, cardiac magnetic resonance (CMR) imaging, using CMR and RT3DE data sets from healthy children and from patients with congenital heart disease.

METHODS

Sixty individuals (20 healthy persons, 40 with congenital heart defects; age range, 2.3-43.9 years; median age, 11.3 years) consecutively underwent investigation by CMR and RT3DE imaging. CMR data sets were first quantified by the method of disks (MOD) as the standard. Then CMR and RT3DE data sets were quantified using KBR software and compared with the MOD.

RESULTS

CMR was more feasible than echocardiography (100% vs 88%). Compared with the MOD (CMRMOD), there were trivial volume overestimations of KBR for CMR data (CMRKBR), of end-diastolic volume (EDV) (-1.3 ± 8.6%, r = 0.984) and end-systolic volume (ESV) (-3.4 ± 13.3%, r = 0.985), resulting in a 0.7 ± 8.7% difference in ejection fraction (EF) (r = 0.882). Comparing CMRMOD and RT3DE imaging, EDV (1.1 ± 7.4%, r = 0.990) and EF (0.8 ± 9.2%, r = 0.871) were slightly underestimated by RT3DE imaging, with a slight overestimation of ESV (-1.5 ± 13.3%, r = 0.977). Intraobserver variability was excellent for KBR of CMR and RT3DE data, with interclass coefficients of correlation of 0.995 and 0.997 for EDV, 0.995 and 0.994 for ESV, and 0.915 and 0.912 for EF. Interobserver variability provided intraclass correlation coefficients of 0.992 and 0.990 for EDV, 0.997 and 0.992 for ESV, and 0.953 and 0.933 for EF. The KBR analysis required a mean time of 5 min.

CONCLUSIONS

KBR is an accurate, versatile, and time-saving method for right ventricular three-dimensional volumetry; it shows excellent reproducibility for RT3DE and CMR data sets. These results suggest that this tool is clinically valuable.

Reference absolute and indexed values for left and right ventricular volume, function and mass from cardiac computed tomography

INTRODUCTION

Left ventricular (LV) and right ventricular (RV) volumetric and functional parameters are important biomarkers for morbidity and mortality in patients with heart failure.

PURPOSE

To retrospectively determine reference mean values of LV and RV volume, function and mass normalised by age, gender and body surface area (BSA) from retrospectively electrocardiographically gated 64-slice cardiac computed tomography (CCT) by using automated analysis software in healthy adults.

MATERIALS AND METHODS

The study was approved by the institutional review board with a waiver of informed consent. Seventy-four healthy subjects (49% female, mean age 49.6 ± 11) free of hypertension and hypercholesterolaemia with a normal CCT formed the study population. Analyses of LV and RV volume (end-diastolic, end-systolic and stroke volumes), function (ejection fraction), LV mass and inter-rater reproducibility were performed with commercially available analysis software capable of automated contour detection. General linear model analysis was performed to assess statistical significance by age group after adjustment for gender and BSA. Bland-Altman analysis assessed the inter-rater agreement.

RESULTS

The reference range for LV and RV volume, function, and LV mass was normalised to age, gender and BSA. Statistically significant differences were noted between genders in both LV mass and RV volume (P-value < 0.0001). Age, in concert with gender, was associated with significant differences in RV end-diastolic volume and LV ejection fraction (P-values 0.027 and 0.03). Bland-Altman analysis showed acceptable limits of agreement (±1.5% for ejection fraction) without systematic error.

CONCLUSION

LV and RV volume, function and mass normalised to age, gender and BSA can be reported from CCT datasets, providing additional information important for patient management.

Assessment of right ventricular volumes in hypoplastic left heart syndrome by real-time three-dimensional echocardiography: comparison with cardiac magnetic resonance imaging

BACKGROUND

Accurate assessment of right ventricular (RV) volumes and function is important in patients with hypoplastic left heart syndrome (HLHS). We prospectively sought to determine the reproducibility of three-dimensional (3D) echocardiography and its agreement with cardiac magnetic resonance imaging (CMR) in HLHS.

METHODS AND RESULTS

Twenty-eight patients underwent CMR followed immediately by transthoracic 3D echocardiography under general anaesthesia. Semi-automated border detection software was used to determine echocardiographic RV volumes. Inter- and intra-observer variability, correlation and levels of agreement between techniques were determined. The median age was 0.37 years (0.18-9.28 years) and weight 6.24 kg (3.42-32.50 kg). Intra- and inter-observer variability was excellent for both techniques. Median (range) measurements for 3D echocardiography and CMR were; end-diastolic volume (EDV) 23.6 mL (6.5-63.2) and 30.6 mL (11.8-87.9), end-systolic volume (ESV) 12.6 mL (3.7-37.0) and 14.9 mL (5.8-33.9), stroke volume (SV) 11.2 mL (2.8-33.0) and 17.1 mL (6.0-54.1), ejection fraction (EF) 48.2% (31.2-64.9), and 56.5% (42.7-72.2). Correlation coefficients were r = 0.85, 0.84, 0.83, and 0.74, respectively (P < 0.01 for all). Volumetric data were expressed as a percentage of the echocardiographic volume to CMR volume. When compared with CMR, 3D echocardiography underestimated EDV, ESV and SV by 26.7% (SD ± 20.2), 10.6% (±28.1), and 37.5% (±20.1), respectively. The difference in volume appeared largest at low ventricular volumes. EF was 8.3% (±7.3) lower by 3D echocardiography compared with CMR.

CONCLUSION

Both 3D echocardiography and CMR volumes appear highly reproducible. Measurements obtained by 3D echocardiography are significantly lower than those obtained by CMR, with wide limits of agreement such that these two methods cannot be used interchangeably.

Subharmonic microbubble emissions for noninvasively tracking right ventricular pressures

Right heart catheterization is often required to monitor intra-cardiac pressures in a number of disease states. Ultrasound contrast agents can produce pressure modulated subharmonic emissions that may be used to estimate right ventricular (RV) pressures. A technique based on subharmonic acoustic emissions from ultrasound contrast agents to track RV pressures noninvasively has been developed and its clinical potential evaluated. The subharmonic signals were obtained from the aorta, RV, and right atrium (RA) of five anesthetized closed-chest mongrel dogs using a SonixRP ultrasound scanner and PA4-2 phased array. Simultaneous pressure measurements were obtained using a 5-French solid state micromanometer tipped catheter. Initially, aortic subharmonic signals and systemic blood pressures were used to obtain a calibration factor in units of millimeters of mercury per decibel. This factor was combined with RA pressures (that can be obtained noninvasively) and the acoustic data from the RV to obtain RV pressure values. The individual calibration factors ranged from -2.0 to -4.0 mmHg/dB. The subharmonic signals tracked transient changes in the RV pressures within an error of 0.6 mmHg. Relative to the catheter pressures, the mean errors in estimating RV peak systolic and minimum diastolic pressures, and RV relaxation [isovolumic negative derivative of change in pressure over time (-dP/dt)] by use of the subharmonic signals, were -2.3 mmHg, -0.8 mmHg, and 2.9 mmHg/s, respectively. Overall, acoustic estimates of RV peak systolic and minimum diastolic pressures and RV relaxation were within 3.4 mmHg, 1.8 mmHg, and 5.9 mmHg/s, respectively, of the measured pressures. This pilot study demonstrates that subharmonic emissions from ultrasound contrast agents have the potential to noninvasively track in vivo RV pressures with errors below 3.5 mmHg.

Single beat 3D echocardiography for the assessment of right ventricular dimension and function after endurance exercise: Intraindividual comparison with magnetic resonance imaging

Background

Our study compares new single beat 3D echocardiography (sb3DE) to cardiovascular magnetic resonance imaging (CMR) for the measurement of right ventricular (RV) dimension and function immediately after a 30 km run. This is to validate sb3DE against the "gold standard" CMR and to bring new insights into acute changes of RV dimension and function after endurance exercise.

Methods

21 non-elite male marathon runners were examined by sb3DE (Siemens ACUSON SC2000, matrix transducer 4Z1c, volume rates 10-29/s), CMR (Siemens Magnetom Avanto, 1,5 Tesla) and blood tests before and immediately after each athlete ran 30 km. The runners were not allowed to rehydrate after the race. The order of sb3DE and CMR examination was randomized.

Results

Sb3DE for the acquisition of RV dimension and function was feasible in all subjects. The decrease in mean body weight and the significant increase in hematocrit indicated dehydration. RV dimensions measured by CMR were consistently larger than measured by sb3DE.

Neither sb3DE nor CMR showed a significant difference in the RV ejection fraction before and after exercise. CMR demonstrated a significant decrease in RV dimensions. Measured by sb3DE, this decrease of RV volumes was not significant.

Conclusion

First, both methods agree well in the acquisition of systolic RV function. The dimensions of the RV measured by CMR are larger than measured by sb3DE. After exercise, the RV volumes decrease significantly when measured by CMR compared to baseline.

Second, endurance exercise seems not to induce acute RV dysfunction in athletes without rehydration.

3D Echo systematically underestimates right ventricular volumes compared to cardiovascular magnetic resonance in adult congenital heart disease patients with moderate or severe RV dilatation

BACKGROUND

Three dimensional echo is a relatively new technique which may offer a rapid alternative for the examination of the right heart. However its role in patients with non-standard ventricular size or anatomy is unclear. This study compared volumetric measurements of the right ventricle in 25 patients with adult congenital heart disease using both cardiovascular magnetic resonance (CMR) and three dimensional echocardiography.

METHODS

Patients were grouped by diagnosis into those expected to have normal or near-normal RV size (patients with repaired coarctation of the aorta) and patients expected to have moderate or worse RV enlargement (patients with repaired tetralogy of Fallot or transposition of the great arteries). Right ventricular end diastolic volume, end systolic volume and ejection fraction were compared using both methods with CMR regarded as the reference standard

RESULTS

Bland-Altman analysis of the 25 patients demonstrated that for both RV EDV and RV ESV, there was a significant and systematic under-estimation of volume by 3D echo compared to CMR. This bias led to a mean underestimation of RV EDV by -34% (95%CI: -91% to + 23%). The degree of underestimation was more marked for RV ESV with a bias of -42% (95%CI: -117% to + 32%). There was also a tendency to overestimate RV EF by 3D echo with a bias of approximately 13% (95% CI -52% to +27%).

CONCLUSIONS

Statistically significant and clinically meaningful differences in volumetric measurements were observed between the two techniques. Three dimensional echocardiography does not appear ready for routine clinical use in RV assessment in congenital heart disease patients with more than mild RV dilatation at the current time.

Reference values of right ventricular end-diastolic area defined by ethnicity and gender in a young adult population: the CARDIA study

BACKGROUND

Despite increasing availability of three-dimensional imaging modalities for estimating right ventricular (RV) size, linear and two-dimensional measures of RV size are the most universally accessible clinical methods. Right ventricular end-diastolic area (RVED area) is known to identify pulmonary pathologies and have prognostic value for cardiovascular mortality in various disease states. To date, there is a paucity of adequately powered studies to define gender- and ethnicity-related differences in normal RVED area. Therefore, we derived gender-based normative values for echocardiographic measurements of RVED area, in a large bi-racial cohort of young adults.

METHODS

Healthy young adults participants (n = 2088) in the Coronary Artery Risk Development in Young Adults (CARDIA) study, aged 23-35 years, at the time of echocardiogram, were evaluated. RVED area was stratified according to gender and race. The contributions of clinical, allometric and left heart morphology and function to the variability in RVED area were determined.

RESULTS

RVED area in males was significantly larger than in females of similar age, but whites had similar values compared to same-gender blacks. RVED area for men and women of >24.7 cm(2) and 20.7cm(2) , or RVED area indexed to BSA (cm(2) /m(2) ) of >12.6 and >11.7, respectively, are at the 97.5th percentile of normal values. RVED area correlated significantly with left ventricular volume and left atrial size. Lung capacity measured as FVC showed significant body size adjusted correlation with RVED area only in black males.

CONCLUSIONS

This study provides normative values for echocardiographically defined RV end-diastolic area, and highlights the necessity to use gender-specific normative values.

Imaging the right ventricle--current state of the art

The right ventricle has long been the 'forgotten ventricle', as it is difficult to image owing to its complex morphology, its thin wall with coarse trabeculations, and its anterior position within the chest. Developments in cardiac magnetic resonance imaging (CMR) and echocardiography have provided new insights into right ventricular (RV) structure and function. RV performance seems to be an important determinant of clinical status and long-term outcome in patients with pulmonary hypertension, cardiomyopathies, and, especially, in patients with congenital heart disease. A variety of different parameters can be measured to assess RV function, but a lot of uncertainty remains on how to assess RV performance in daily clinical practice and which measurements to use in clinical decision-making. CMR is currently considered the reference technique for RV volumetry and calculation of ejection fraction. Various echocardiographic techniques can provide reliable information on RV dimensions and RV systolic and diastolic function that can be used in clinical follow-up. The introduction of newer echocardiographic techniques, such as three-dimensional echocardiography, tissue Doppler ultrasonography, and ultrasound strain imaging, challenge the leading role of CMR in RV functional assessment, but further validation and accumulation of data are required before these techniques can play a key part in clinical decision-making.

Echocardiography for assessment of right ventricular volumes revisited: a cardiac magnetic resonance comparison study in adults with repaired tetralogy of Fallot

BACKGROUND

The aim of this study was to develop a mathematical model using two-dimensional echocardiographic parameters to estimate right ventricular end-diastolic volume (RVEDVi) in adults with repaired tetralogy of Fallot.

METHODS

Linear regression equations were used to examine the relationship between two-dimensional echocardiographic and cardiac magnetic resonance (CMR) imaging measures of RVEDVi. Imaging studies in 101 adults were used to create and validate the model. The ability of the model to detect changes in CMR RVEDVi was tested in 57 adults with serial studies.

RESULTS

The optimal model to quantitate CMR RVEDVi included two-dimensional echocardiographic right ventricular end-diastolic area measured in the apical four-chamber view, indexed to body surface area (AreaDi) (CMR RVEDVi = 11.5 + [7 x AreaDi]). The model reliably allowed the detection of stable and changing CMR RVEDVi (kappa = 0.84 and kappa = 0.82, respectively, P < .0001).

CONCLUSION

Quantitative assessment of right-ventricular volumes by echocardiography is feasible and may be used for serial follow-up in patients with contraindications for CMR.