The limited usefulness of real-time 3-dimensional echocardiography in obtaining normal reference ranges for right ventricular volumes

Added value of 3D echocardiography in the diagnosis and prognostication of patients with right ventricular dysfunction

Recent inroads into percutaneous-based options for the treatment of tricuspid valve disease has brought to light how little we know about the behavior of the right ventricle in both health and disease and how incomplete our assessment of right ventricular (RV) physiology and function is using current non-invasive technology, in particular echocardiography. The purpose of this review is to provide an overview of what three-dimensional echocardiography (3DE) can offer currently to enhance RV evaluation and what the future may hold if we continue to improve the 3D evaluation of the right heart.

Standardization of normal values for cardiac chamber size in echocardiography

Echocardiography is used worldwide to evaluate cardiac size and function. To determine what values are abnormal, it is essential to establish normal reference values for echocardiography. The current guidelines for chamber quantification specify normative values for cardiac chambers and recommend that gender and body size be taken into account. However, these normative data were established using databases for which a variety of measurement methods were used and the majority of subjects consisted of Whites in Europe and the United States. However, several regional studies from other countries suggest that cardiac size varies globally. To overcome these limitations, the Normal Reference Ranges for Echocardiography study and the World Alliance of Societies of Echocardiography Normal Values study have recently been conducted to examine similarities and differences in cardiac chamber size and to establish normal reference values while taking worldwide diversity into account. The results from these studies have demonstrated that standardization of normal reference values for cardiac size is important. This review article aims to summarize the current status of normative echocardiographic values for cardiac chamber size.

Reference Values of Right Ventricular Volumes and Ejection Fraction by Three-Dimensional Echocardiography in Adults: A Systematic Review and Meta-Analysis

Objective: This study was conducted in order to determine the reference values for right ventricular (RV) volumes and ejection fraction (EF) using three-dimensional echocardiography (3DE) and to identify sources of variance through a systematic review and meta-analysis.

Methods: This systematic review was preregistered with the International Prospective Register of Systematic Reviews (https://www.crd.york.ac.uk/PROSPERO/) (CRD42020211002). Relevant studies were identified by searches of the PubMed, Embase, and Cochrane Library databases through October 12, 2020. Pooled reference values were calculated using the random-effects model weighted by inverse variance. Meta-regression analysis and Egger's test were used to determine the source of heterogeneity. A subgroup analysis was performed to evaluate the reference values across different conditions.

Results: The search identified 25 studies of 2,165 subjects. The mean reference values were as follows: RV end-diastolic volume, 100.71 ml [95% confidence interval (CI), 90.92–110.51 ml); RV end-systolic volume, 44.19 ml (95% CI, 39.05–49.33 ml); RV end-diastolic volume indexed, 57.01 ml/m² (95% CI, 51.93–62.08 ml/m²); RV end-systolic volume indexed, 25.41 ml/m² (95% CI, 22.58–28.24 ml/m²); and RVEF, 56.20% (95% CI, 54.59–57.82%). The sex- and age-specific reference values were assessed according to the studies reporting the values of different sexes and age distributions, respectively. In addition, the vendor- and software-specific reference values were analyzed. The meta-regression analysis revealed that sex, frame rate, pulmonary artery systolic pressure, and software packages were associated with variations in RV volumes (P < 0.05). Inter-vendor and inter-software discrepancies may explain the variability of RVEF.

Conclusions: The reference values for RV volumes and RVEF using 3DE were assessed. The confounders that impacted the variability in RV volumes or RVEF contained the sex, frame rate, pulmonary artery systolic pressure, inter-vendor discrepancies, and inter-software discrepancies.

Sex- and Age-Related Reference Values in Cardiology, with Annotations and Guidelines for Interpretation

The definition of "abnormal" in clinical sciences is often based on so-called reference values which point to a range that experts by some sort of consensus consider as normal when looking at biological variables. Such a level is commonly calculated by taking (twice) the standard deviation from the mean, or considering certain percentiles. The suspicion or even confirmation of a disease is then established by demonstrating that the value measured exceeds the upper or lower reference value. As is often the case, the measurement accuracy may depend on the conditions and specific method employed to collect and analyze data. This implies that, for example, data assessed by 2D echocardiography possibly differ from those obtained by MRI and therefore require modality-specific reference values. In this review we summarize reference values for the electrocardiogram, cardiac compartmental volumes, and arterial vessel size in males and females for various age groups. These values may further depend on other variables such as body size, physical training status, and ethnicity. Additional variables relevant for cardiology such as those referring to the microcirculation and biomarkers are only mentioned with reference to the pertinent literature. In general, the sex- and age-specific differences observed are often remarkable and warrant consideration in clinical practice and basic biomedical sciences.

Assessment of right ventricular volumes and ejection fraction by echocardiography: from geometric approximations to realistic shapes

Right ventricular volumes and ejection fraction are challenging to assess by echocardiography, but are well established as functional and prognostic parameters. Three-dimensional (3D) echocardiography has become widespread and relatively easy to use, making calculation of these parameters feasible in the large majority of patients. We review past attempts to estimate right ventricular volumes, current strengths and weaknesses of 3D echocardiography for this task, and compare with corresponding data from magnetic resonance imaging.

Right ventricular outflow tract systolic excursion: a useful method for determining right ventricular systolic function

BACKGROUND

Assessment of right ventricular (RV) systolic function is not an easy task. Although RV fractional area change (FAC) and tricuspid annular plane systolic excursion (TAPSE) are useful in the assessment of RV function, their use can be sometimes limited. Right ventricular outflow tract systolic excursion (RVOT_SE) is a new way to evaluate RV systolic function. The aim of this study was to assess the correlation between RVOT_SE and other RV systolic function assessment methods.

METHODS

RVOT_SE was defined as the systolic excursion of the RV outflow tract anterior wall endocardium. A total of 104 patients with a wide range of RV systolic function, ejection fraction, and pulmonary artery systolic pressure were studied. We also measured another four ways to evaluate RV systolic function, FAC, TAPSE, right ventricular outflow tract fractional shortening (RVOT_FS), and tricuspid annular systolic excursion velocity S' (Tissue S').

RESULTS

There was a strong correlation between RVOT_SE and each one of the four studied ways to evaluate RV systolic function. Multivariate regression analysis showed that the independent variables correlated with RVOT_SE were RVOT_FS (p < 0.0001), FAC (p = 0.005) and TAPSE (p = 0.023). RVOT_SE diagnosed patients with reduced RV systolic function with 98 % sensitivity and 96 % specificity. There was no correlation between RVOT_SE and ejection fraction, or between RVOT_SE and pulmonary artery systolic pressure in patients with reduced RV systolic function. Intra-observer and inter-observer reproducibility were favorable for RVOT_SE and all four studied ways.

CONCLUSIONS

RVOT_SE is a simple, accurate, and promising method for evaluating RV systolic function.

Analysis of transthoracic echocardiographic data in major vascular surgery from a prospective randomised trial comparing sevoflurane and fentanyl with propofol and remifentanil anaesthesia

The aim of this study was to define pre-operative echocardiographic data and explore if postoperative indices of cardiac function after open abdominal aortic surgery were affected by the anaesthetic regimen. We hypothesised that volatile anaesthesia would improve indices of cardiac function compared with total intravenous anaesthesia. Transthoracic echocardiography was performed pre-operatively in 78 patients randomly assigned to volatile anaesthesia and 76 to total intravenous anaesthesia, and compared with postoperative data. Pre-operatively, 16 patients (10%) had left ventricular ejection fraction < 46%. In 138 patients with normal left ventricular ejection fraction, 5/8 (62%) with left ventricular dilatation and 41/130 (33%) without left ventricular dilatation had evidence of left ventricular diastolic dysfunction (p < 0.001). Compared with pre-operative findings, significant increases in left ventricular end-diastolic volume, left atrial maximal volume, cardiac output, velocity of early mitral flow and early myocardial relaxation occurred postoperatively (all p < 0.001). The ratio of the velocity of early mitral flow to early myocardial relaxation remained unchanged. There were no significant differences in postoperative echocardiographic findings between patients anaesthetised with volatile anaesthesia or total intravenous anaesthesia. Patients had an iatrogenic surplus of approximately 4.1 l of fluid volume by the first postoperative day. N-terminal prohormone of brain natriuretic peptide increased on the first postoperative day (p < 0.001) and remained elevated after 30 days (p < 0.001) in both groups. Although postoperative echocardiographic alterations were most likely to be related to increased preload due to a substantial iatrogenic surplus of fluid, a component of peri-operative myocardial ischaemia cannot be excluded. Our hypothesis that volatile anaesthesia improved indices of cardiac function compared with total intravenous anaesthesia could not be verified.

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.