A closer look at right ventricular 3D volume quantification by transthoracic echocardiography and cardiac MRI

Aortic stenosis and right ventricular dysfunction

At the present time, right ventricular function in patients with aortic stenosis is insufficiently taken into account in the decision-making process of aortic valve replacement. The aim of our study was to evaluate significance of right ventricular dysfunction in patients with severe aortic stenosis by modern 3D echocardiographic methods. This is prospective analysis of 68 patients with severe high and low-gradient aortic stenosis. We evaluated function of left and right ventricle on the basis of 3D reconstruction. Enddiastolic, endsystolic volumes, ejection fraction and stroke volumes of both chambers were assessed. There were more patients with right ventricular dysfunction in low-gradient group (RVEF < 45%) than in the high-gradient group (63.6% vs 39%, p = 0.02). Low-gradient patients had worse right ventricular function than high-gradient patients (RVEF 36% vs 46%, p = 0.02). There wasn't any significant correlation between the right ventricular dysfunction and pulmonary hypertension (r = - 0.25, p = 0.036). There was significant correlation between left and right ejection fraction (r = 0.78, p < 0.0001). Multiple regression analysis revealed that the only predictor of right ventricular function is the left ventricular function. According to our results we can state that right ventricular dysfunction is more common in patients with low-gradient than in high-gradient aortic stenosis and the only predictor of right ventricular dysfunction is left ventricular dysfunction, probably based on ventriculo-ventricular interaction. Pulmonary hypertension in patients with severe AS does not predict right ventricular dysfunction.

Right ventricular ejection fraction derived from intraoperative three-dimensional transesophageal echocardiography versus cardiac magnetic resonance imaging

PURPOSE

Right ventricle (RV) assessment is critical during cardiac surgery. Traditional assessment consists of visual estimation and measurement of validated parameters. Cardiac magnetic resonance imaging (cMRI) is the gold standard for RV analysis, and transthoracic three-dimensional (3D) echocardiography is validated against this. We aimed to show that intraoperative 3D transesophageal echocardiography (TEE) RV assessment is feasible and can produce results that correlate with cMRI.

METHODS

We recruited cardiac surgery patients who underwent cMRI within the preceding twelve preoperative months. An anesthetic protocol was followed pre-sternotomy and a 3D RV data set was acquired. We used TOMTEC 4D RV-Function to derive RV end-diastolic volume (EDV), end-systolic volume (ESV), and ejection fraction (EF). We compared these data with the corresponding MRI values.

RESULTS

Twenty-five patients were included. Transesophageal echocardiography EDV and ESV differed from MRI measurements with a mean bias of -53 mL (95% confidence interval [CI], -80 to 26) and -21 mL (95% CI, -34 to -9). Transesophageal echocardiography EF did not differ significantly, with a mean bias of -4% (95% CI, -8 to 1). Results were unchanged after excluding MRIs older than 180 days. Correlation coefficients for EDV, ESV, and EF were r = 0.85, 0.91, and 0.80, respectively. Interclass correlation coefficients for EDV, ESV, and EF were 0.86, 0.89, and 0.96, respectively.

CONCLUSIONS

Intraoperative TEE RV, EDV, and ESV are underestimated relative to cMRI because of analysis, anesthetic, and ventilation factors. The EF showed a low mean difference, and all values showed strong correlation with MRI. Reproducibility and feasibility were excellent and increased use in clinical practice should be considered.

Assessment of Right Ventricle Function and Tricuspid Regurgitation in Heart Failure: Current Advances in Diagnosis and Imaging

Right ventricular (RV) systolic dysfunction increases mortality among heart failure patients, and therefore, accurate diagnosis and monitoring is paramount. RV anatomy and function are complex, usually requiring a combination of imaging modalities to completely quantitate volumes and function. Tricuspid regurgitation usually occurs with RV dysfunction, and quantifying this valvular lesion also may require multiple imaging modalities. Echocardiography is the first-line imaging tool for identifying RV dysfunction, with cardiac MRI and cardiac computed tomography adding valuable additional information.

Pressure Volume Loop Analysis of the Right Ventricle in Heart Failure With Computed Tomography

Right ventricular (RV) function is an important marker of mortality in chronic left-sided heart failure. Right ventricular function is particularly important for patients receiving left ventricular assist devices as it is a predictor of postoperative RV failure. RV stroke work index (RVSWI), the area enclosed by a pressure-volume (PV) loop, is prognostic of RV failure. However, clinical RVSWI approximates RVSWI as the product of thermodilution-derived stroke volume and the pulmonary pressure gradient. This ignores the energetic contribution of regurgitant flow and does not allow for advanced energetic measures, such as pressure-volume area and efficiency. Estimating RVSWI from forward flow may underestimate the underlying RV function. We created single-beat PV loops by combining data from cine computed tomography (CT) and right heart catheterization in 44 heart failure patients, tested the approximations made by clinical RVSWI and found it to underestimate PV loop RVSWI, primarily due to regurgitant flow in tricuspid regurgitation. The ability of RVSWI to predict post-operative RV failure improved when the single-beat approach was used. Further, RV pressure-volume area and efficiency measures were obtained and show broad agreement with other functional measures. Future work is needed to investigate the utility of these PV metrics in a clinical setting.

Pressure-based beat-to-beat right ventricular ejection fraction and Tau from continuous measured ventricular pressures in COVID-19 ARDS patients

We evaluated pressure-based right ventricular ejection fraction (RVEF) and diastolic isovolumetric relaxation time constant (Tau) from continuously (up to 30 days) invasive measured right ventricular pressures in mechanically ventilated patients with severe COVID-19 acute respiratory distress syndrome (ARDS). We retrospectively calculated beat-to-beat ejection fraction from right ventricular pressures and dp/dt maximum and minimum in 39 patients treated between October 1st, 2020 and June 30th, 2021. After performing a stepwise logistic regression with survival as a dependent variable, we divided the patients into survivors and nonsurvivors based on their 60-day mortality. Independent outcome variables were the values of RVEF and Tau over time after insertion of the right ventricular probe along with right ventricular systolic and diastolic pressures (RVSP) and the estimated pulmonary artery diastolic pressure (ePAD). RVEF increased significantly over time in the survivors (estimate: 0.354; 95% confidence interval, CI: 0.18-0.53; p < 0.001) but remained unchanged in the nonsurvivors. Tau increased significantly in the nonsurvivors (estimate: 0.001; 95% CI: 0.0004-0.0018; p < 0.002) but not in the survivors. On the last measurement day, RVSP and ePAD were significantly lower while RVEF was significantly higher in the survivors compared to the nonsurvivors. In COVID-19 ARDS patient's, calculation of beat-to-beat RVEF and Tau from continuously invasive measured right ventricular pressures seems to unravel contrary trends in RVEF with an increase in the surviving and a decrease in the nonsurviving patients. Tau remained unchanged in the surviving but increased in the nonsurviving patients over time.

High-echoic line tracing of transthoracic echocardiography accurately assesses right ventricular enlargement in adult patients with atrial septal defect

Accurate measurement of right ventricular (RV) size using transthoracic echocardiography (TTE) is important for evaluating the severity of congenital heart diseases. The RV end-diastolic area index (RVEDAi) determined using TTE is used to assess RV dilatation; however, the tracing line of the RVEDAi has not been clearly defined by the guidelines. This study aimed to determine the exact tracing method for RVEDAi using TTE. We retrospectively studied 107 patients with atrial septal defects who underwent cardiac magnetic resonance imaging (CMR) and TTE. We measured the RVEDAi according to isoechoic and high-echoic lines, and compared it with the RVEDAi measured using CMR. The isoechoic line was defined as the isoechoic endocardial border of the RV free wall, whereas the high-echoic line was defined as the high-echoic endocardial border of the RV free wall more outside than the isoechoic line. RVEDAi measured using high-echoic line (high-RVEDAi) was more accurately related to RVEDAi measured using CMR than that measured using isoechoic line (iso-RVEDAi). The difference in the high-RVEDAi was 0.3 cm²/m², and the limit of agreement (LOA) was - 3.7 to 4.3 cm²/m². With regard to inter-observer variability, high-RVEDAi was superior to iso-RVEDAi. High-RVEDAi had greater agreement with CMR-RVEDAi than with iso-RVEDAi. High-RVEDAi can become the standard measurement of RV size using two-dimensional TTE.

Evaluation of right ventricle systolic function after tetralogy of Fallot repair: A systematic review comparing cardiac magnetic resonance and global longitudinal strain

BACKGROUND

Most patients who undergo tetralogy of Fallot (TOF) repair experience late right ventricle (RV) dysfunction due to pulmonary valve regurgitation (PVR). Cardiac magnetic resonance (CMR) is the gold standard method for evaluating RV during follow-up. Global longitudinal strain (GLS) has been introduced as a novel method for the assessment of RV dysfunction. We aimed to compare the feasibility of GLS and CMR for assessing RV function after TOF repair.

METHODS

We systematically reviewed the English literature using PubMed, SciELO and Google Scholar for articles published between January 1, 2015, and December 31, 2020. Articles evaluating RV function comparing by GLS and CMR after TOF repair were included.

RESULTS

Nine studies including 465 patients were analyzed. Most patients were men (280; 60%), the male:female ratio was 1.5:1, and the age range was .8 to 57.7 years. The mean follow-up time was 6 to 32 months. The correlation between RV GLS and RV ejection fraction (EF) by CMR was negative for the articles and varied from moderate to strong (r = -.45, r = -.60, r = -.76).

CONCLUSION

Right ventricle GLS can be considered for routine follow-up of TOF repair patients, even though CMR remains the noninvasive gold standard method. Using a single parameter may not allow comparison of the accuracy of 3D RV EF by using CMR and GLS. Further studies with a larger number of patients undergoing TOF repair are required to evaluate the correlation between these examinations.

Lateral annular systolic excursion ratio: A novel measurement of right ventricular systolic function by two-dimensional echocardiography

Introduction

Accurate assessment of right ventricular (RV) systolic function has prognostic and therapeutic implications in many disease states. Echocardiography remains the most frequently deployed imaging modality for this purpose, but estimation of RV systolic function remains challenging. The purpose of this study was to evaluate the diagnostic performance of a novel measurement of RV systolic function called lateral annular systolic excursion ratio (LASER), which is the fractional shortening of the lateral tricuspid annulus to apex distance, compared to right ventricular ejection fraction (RVEF) derived by cardiac magnetic resonance imaging (CMR).

Methods

A retrospective cohort of 78 consecutive patients who underwent clinically indicated CMR and transthoracic echocardiography within 30 days were identified from a database. Parameters of RV function measured included: tricuspid annular plane systolic excursion (TAPSE) by M-mode, tissue Doppler S', fractional area change (FAC) and LASER. These measurements were compared to RVEF derived by CMR using Pearson's correlation coefficients and receiver operating characteristic curves.

Results

LASER was measurable in 75 (96%) of patients within the cohort. Right ventricular systolic dysfunction, by CMR measurement, was present in 37% (n = 29) of the population. LASER has moderate positive correlation with RVEF (r = 0.54) which was similar to FAC (r = 0.56), S' (r = 0.49) and TAPSE (r = 0.37). Receiver operating characteristic curves demonstrated that LASER (AUC = 0.865) outperformed fractional area change (AUC = 0.767), tissue Doppler S' (AUC = 0.744) and TAPSE (AUC = 0.645). A cohort derived dichotomous cutoff of 0.2 for LASER was shown to provide optimal diagnostic characteristics (sensitivity of 75%, specificity of 87% and accuracy of 83%) for identifying abnormal RV function. LASER had the highest sensitivity, accuracy, positive and negative predictive values among the parameters studied in the cohort.

Conclusions

Within the study cohort, LASER was shown to have moderate positive correlation with RVEF derived by CMR and more favorable diagnostic performance for detecting RV systolic dysfunction compared to conventional echocardiographic parameters while being simple to obtain and less dependent on image quality than FAC and emerging techniques.

Volumetric Evaluation of Dead Space in Ischial Pressure Injuries Using Magnetic Resonance Imaging: A Case Series

OBJECTIVE

To establish a preoperative evaluation procedure by measuring the volume of dead space using MRI in patients with ischial pressure injuries.

METHODS

Patients with spinal cord injury and ischial pressure injuries who underwent treatment between August 2016 and November 2019 were included in the study. Preoperative MRI scan was conducted on all patients. The volume estimation and three-dimensional (3D) reconstruction were performed based on MRI data using a 3D Slicer. Based on the resulting volume, a muscle flap that could fit the dead space was selected. Surgery was performed with the selected muscle flap, and a fasciocutaneous flap was added, if necessary.

RESULTS

A total of eight patients with ischial pressure injuries were included in the study. The mean patient age was 59.0 ± 11.0 years. The mean body mass index was 26.62 ± 3.89 kg/m2. The mean volume of dead space was 104.75 ± 81.05 cm3. The gracilis muscle was the most selected muscle flap and was used in four patients. In five of eight cases, a fasciocutaneous flap was used as well. The mean follow-up period was 16 months, and by that point, none of the patients evinced complications that required surgery.

CONCLUSIONS

To the authors' knowledge, this is the first report on volumetric evaluation of dead space in ischial pressure injuries. The authors believe that the 3D reconstruction process would enable adequate dead space obliteration in ischial pressure injuries. The authors propose that preoperative MRI scans in patients with ischial pressure injury should become an essential part of the process.

Accuracy and sensitivity of three-dimensional echocardiography to detect changes in right ventricular volumes: comparison study with cardiac magnetic resonance

We aimed to investigate the ability of three-dimensional transthoracic echocardiography (3DE) to detect changes in RV volumes compared to cardiac magnetic resonance (CMR). Eighty-five subjects including 45 with no known cardiac disease and 40 patients with a variety of cardiac diseases were included. Two- and three-dimensional echocardiography as well as CMR of the RV was performed before and after infusion of on average two litres of saline. Examinations were analysed with estimation of RV dimensions, volumes and ejection fraction (RVEF). Intra- and inter-examiner variability was evaluated in 25 patients randomly selected from the cohort. Three-dimensional echocardiography underestimated volumes and RVEF compared to CMR with mean differences and 95% limits of agreement of 110.3 ± 59 mL for RV end-diastolic volume (RVEDV), 43.3 ± 32 mL for RV end-systolic volume (RVESV) and 3.5 ± 10.7% for RVEF. CMR was more reproducible than 3DE, with intra-observer coefficient of variation (CV) of 4% vs. 14.2% for RVEDV, 9.7% vs. 16.7% for RVESV and 6.3% vs. 8.6% for RVEF. The RVEDV, RVESV and RV stroke volume (RVSV) by CMR significantly increased after saline infusion by 15.3 ± 16.2 mL, 3.5 ± 14.2 mL and 11.8 ± 12.6 mL, respectively, as well as RVEF by 1.5 ± 4.6% (p < 0.05). However, 3DE was not able to detect any of these changes in RV volumes (p ≥ 0.05). Compared to CMR imaging of the RV, three-dimensional echocardiography appears unable and unreliable in detecting RV volume changes of less than 15%, highlighting the need for cautious utility of 3DE in these circumstances.