Characterization of Right Ventricular Deformation in Pulmonary Arterial Hypertension Using Three-Dimensional Principal Strain Analysis

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.

Three-Dimensional, Right Ventricular Surface Strain Computation From Three-Dimensional Echocardiographic Images From Patients With Pediatric Pulmonary Hypertension

Right Ventricular (RV) dysfunction is routinely assessed with echocardiographic-derived global longitudinal strain (GLS). GLS is measured from a two-dimensional echo image and is increasingly accepted as a means for assessing RV function. However, any two-dimensional (2D) analysis cannot visualize the asymmetrical deformation of the RV nor visualize strain over the entire RV surface. We believe three-dimensional surface (3DS) strain, obtained from 3D echo will better evaluate myocardial mechanics. Components of 3DS strain (longitudinal, LS; circumferential, CS; longitudinal-circumferential shear, ɣCL; principal strains PSMax and PSMin; max shear, ɣMax; and principal angle θMax) were computed from RV surface meshes obtained with 3D echo from 50 children with associated pulmonary arterial hypertension (PAH), 43 children with idiopathic PAH, and 50 healthy children by computing strains from a discretized displacement field. All 3DS freewall (FW) normal strain (LS, CS, PSMax, and PSMin) showed significant decline at end-systole in PH groups (p < 0.0001 for all), as did FW-ɣMax (p = 0.0012). FW-θMax also changed in disease (p < 0.0001). Limits of agreement analysis suggest that 3DS LS, PSMax, and PSMin are related to GLS. 3DS strains showed significant heterogeneity over the 3D surface of the RV. Components of 3DS strain agree with existing clinical strain measures, well classify normal -versus- PAH subjects, and suggest that strains change direction on the myocardial surface due to disease. This last finding is similar to that of myocardial fiber realignment in disease, but further work is needed to establish true associations.

Echocardiography Imaging of the Right Ventricle: Focus on Three-Dimensional Echocardiography

Right ventricular function strongly predicts cardiac death and adverse cardiac events in patients with cardiac diseases. However, the accurate right ventricular assessment by two-dimensional echocardiography is limited due to its complex anatomy, shape, and load dependence. Advances in cardiac imaging and three-dimensional echocardiography provided more reliable information on right ventricular volumes and function without geometrical assumptions. Furthermore, the pathophysiology of right ventricular dysfunction and tricuspid regurgitation is frequently connected. Three-dimensional echocardiography allows a more in-depth structural and functional evaluation of the tricuspid valve. Understanding the anatomy and pathophysiology of the right side of the heart may help in diagnosing and managing the disease by using reliable imaging tools. The present review describes the challenging echocardiographic assessment of the right ventricle and tricuspid valve apparatus in clinical practice with a focus on three-dimensional echocardiography.

Normative healthy reference values for global and segmental 3D principal and geometry dependent strain from cine cardiac magnetic resonance imaging

3-Dimensional (3D) myocardial deformation analysis (3D-MDA) enables novel descriptions of geometry-independent principal strain (PS). Applied to routine 2D cine cardiovascular magnetic resonance (CMR), this provides unique measures of myocardial biomechanics for disease diagnosis and prognostication. However, healthy reference values remain undefined. This study describes age- and sex-stratified reference values from CMR-based 3D-MDA, including 3D PS. One hundred healthy volunteers were prospectively recruited following institutional ethics approval and underwent CMR imaging. 3D-MDA was performed using validated software. Age- and sex-stratified global and segmental strain measures were derived for conventional geometry-dependent [circumferential (CS), longitudinal (LS), and radial (RS)] and geometry-independent [minimum (minPS) and maximum principal (maxPS)] directions of deformation. Layer-specific contraction angle interactions were determined using local minPS vectors. The average age was 43 ± 15 years and 55% were women. Strain measures were higher in women versus men. 3D PS-based assessment of maximum tissue shortening (minPS) and maximum tissue thickening (maxPS) were greater than corresponding geometry-dependent markers of LS and RS, consistent with improved representation of local tissue deformations. Global maxPS amplitude best discriminated both age and sex. Segmental analyses showed greater strain amplitudes in apical segments. Transmural PS contraction angles were higher in females and showed a heterogeneous distribution across segments. In this study we provided age and sex-based reference values for 3D strain from CMR imaging, demonstrating improved capacity for 3D PS to document maximal local tissue deformations and to discriminate age and sex phenotypes. Novel markers of layer-specific strain angles from 3D PS were also described.

Association of Three-Dimensional Mesh-Derived Right Ventricular Strain with Short-Term Outcomes in Patients Undergoing Cardiac Surgery

BACKGROUND

Three-dimensional (3D) right ventricular (RV) strain analysis is not routinely performed perioperatively. Although 3D RV strain adds incrementally to outcome prediction in various cardiac diseases, its role in the perioperative setting is not sufficiently understood. The aim of this study was to investigate the association between 3D RV strain measured on RV meshes created from 3D transesophageal echocardiographic data and short-term outcomes among patients undergoing cardiac surgery.

METHODS

A total of 496 patients undergoing cardiac surgery who underwent intraoperative 3D transesophageal echocardiography (under general anesthesia, before sternotomy) were retrospectively selected, and RV meshes were generated using commercially available speckle-tracking software. Custom-made software automatically quantified longitudinal and circumferential RV strains on the mesh surfaces. Echocardiographic and clinical parameters were entered into logistic regression models to determine their associations with the primary (in-hospital death or need for extracorporeal life support) and secondary (postoperative ventilation > 48 hours) end points.

RESULTS

Mesh-derived RV strain analysis was feasible in 94% of patients and revealed distinct regional patterns with basal-apical gradients for both longitudinal and circumferential strain. Thirty-seven patients (7.6%) reached the primary end point, and 118 patients (23.8%) reached the secondary end point. In a multivariable logistic regression model, serum lactate (P < .01), an emergency indication for surgery (P < .01), tricuspid regurgitation (P < .001), and mesh-derived RV global longitudinal strain (RV-GLS; P < .01) were independently associated with the primary end point, while established measures of RV function (3D RV ejection fraction, fractional area change, tricuspid annular plane systolic excursion) and left ventricular (LV) function (3D-derived LV ejection fraction and LV-GLS) were not independently associated. Hematocrit (P < .01), serum lactate (P < .001), pulmonary hypertension (P = .04), tricuspid regurgitation (P < .01), emergency procedures (P = .02), LV-GLS (P = .02), and RV-GLS (P < .001) were associated with the secondary end point.

CONCLUSIONS

RV-GLS measured on RV meshes derived from 3D transesophageal echocardiography was independently associated with short-term outcomes in patients undergoing cardiac surgery and might be helpful for identifying patients at risk for adverse postoperative events.

Unchanged right ventricular strain in repaired tetralogy of Fallot after pulmonary valve replacement with radial long-axis cine magnetic resonance images

We measured right ventricular (RV) strain by applying a novel postprocessing technique to conventional short-axis cine magnetic resonance imaging in the repaired tetralogy of Fallot (TOF) and investigated whether pulmonary valve replacement (PVR) changes the RV strain. Twenty-four patients with repaired TOF who underwent PVR and 16 healthy controls were enrolled. Global maximum and minimum principal strains (GPS_max, GPS_min) and global circumferential and longitudinal strains (GCS, GLS) were measured from short-axis cine images reconstructed radially along the long axis. Strain parameters before and after PVR were compared using paired t-tests. One-way ANOVA with Tukey post-hoc analysis was used for comparisons between the before and after PVR groups and the control group. There were no differences in strain parameters before and after PVR. The GPS_max before PVR was lower than that in the control group (P = 0.002). Before and after PVR, GCSs were higher and GLSs were lower than those in the control group (before and after GCSs: P = 0.002 for both, before and after GLSs: P < 0.0001 and P = 0.0003). RV strains from radially reconstructed short-axis cine images revealed unchanged myocardial motion after PVR. When compared to the control group, changes in GCS and GLS in TOF patients before and after PVR might be due to RV remodeling.

Partitioning the Right Ventricle Into 15 Segments and Decomposing Its Motion Using 3D Echocardiography-Based Models: The Updated ReVISION Method

Three main mechanisms contribute to global right ventricular (RV) function: longitudinal shortening, radial displacement of the RV free wall (bellows effect), and anteroposterior shortening (as a consequence of left ventricular contraction). Since the importance of these mechanisms may vary in different cardiac conditions, a technology being able to assess their relative influence on the global RV pump function could help to clarify the pathophysiology and the mechanical adaptation of the chamber. Previously, we have introduced our 3D echocardiography (3DE)-based solution-the Right VentrIcular Separate wall motIon quantificatiON (ReVISION) method-for the quantification of the relative contribution of the three aforementioned mechanisms to global RV ejection fraction (EF). Since then, our approach has been applied in several clinical scenarios, and its strengths have been demonstrated in the in-depth characterization of RV mechanical pattern and the prognostication of patients even in the face of maintained RV EF. Recently, various new features have been implemented in our software solution to enable the convenient, standardized, and more comprehensive analysis of RV function. Accordingly, in our current technical paper, we aim to provide a detailed description of the latest version of the ReVISION method with special regards to the volumetric partitioning of the RV and the calculation of longitudinal, circumferential, and area strains using 3DE datasets. We also report the results of the comparison between 3DE- and cardiac magnetic resonance imaging-derived RV parameters, where we found a robust agreement in our advanced 3D metrics between the two modalities. In conclusion, the ReVISION method may provide novel insights into global and also segmental RV function by defining parameters that are potentially more sensitive and predictive compared to conventional echocardiographic measurements in the context of different cardiac diseases.

Right ventricular area strain from 3-dimensional echocardiography: Mechanistic insight of right ventricular dysfunction in pediatric pulmonary hypertension

BACKGROUND

Right ventricular (RV) function is a major contributor to the outcome of pulmonary arterial hypertension (PAH). Adult studies demonstrated that regional and global changes in RV deformation are prognostic in PAH using 3-dimensional echocardiography (3DE). However, regional and global dynamic changes in RV mechanics have not been described in pediatric PAH. We compared 3DE RV regional and global deformation between pediatric patients who had associated PAH with congenital heart disease (APAH-CHD), pediatric patients who had idiopathic PAH (IPAH), and normal controls, and evaluated the clinical outcomes.

METHODS

A total of 48 controls, 47 patients with APAH-CHD, and 45 patients with IPAH were evaluated. 3DE RV sequences were analyzed and post-processed to extract global and regional deformation (circumferential, longitudinal, and area strain). Statistical analyses compared the sub-groups on the basis of global and regional deformation, and outcome analysis was performed.

RESULTS

Patients with PAH had significantl8y different global and regional deformation (p < 0.001) compared with controls. Patients with APAH-CHD and and those with IPAH significantly differed in global circumferential strain (p < 0.010), area strain (inlet septum, p = 0.041), and circumferential strain at the inlet septum (p < 0.019), apex free wall (p < 0.004), and inlet free wall (p < 0.004). Circumferential strain at the inlet free wall and circumferential, longitudinal, and area strain at the apex free wall were predictors of adverse events.

CONCLUSIONS

RV regional and global strain differ between controls and pediatric patients with PAH. RV apical free-wall area strain provides insight into the mechanism of RV dysfunction in pediatric patients with PAH, with regional strain emerging as outcome predictors, suggesting that this novel measure may be considered as a future measure of RV function.

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.

Neural-Network-Based Diagnosis Using 3-Dimensional Myocardial Architecture and Deformation: Demonstration for the Differentiation of Hypertrophic Cardiomyopathy

The diagnosis of cardiomyopathy states may benefit from machine-learning (ML) based approaches, particularly to distinguish those states with similar phenotypic characteristics. Three-dimensional myocardial deformation analysis (3D-MDA) has been validated to provide standardized descriptors of myocardial architecture and deformation, and may therefore offer appropriate features for the training of ML-based diagnostic tools. We aimed to assess the feasibility of automated disease diagnosis using a neural network trained using 3D-MDA to discriminate hypertrophic cardiomyopathy (HCM) from its mimic states: cardiac amyloidosis (CA), Anderson–Fabry disease (AFD), and hypertensive cardiomyopathy (HTNcm). 3D-MDA data from 163 patients (mean age 53.1 ± 14.8 years; 68 females) with left ventricular hypertrophy (LVH) of known etiology was provided. Source imaging data was from cardiac magnetic resonance (CMR). Clinical diagnoses were as follows: 85 HCM, 30 HTNcm, 30 AFD, and 18 CA. A fully-connected-layer feed-forward neural was trained to distinguish HCM vs. other mimic states. Diagnostic performance was compared to threshold-based assessments of volumetric and strain-based CMR markers, in addition to baseline clinical patient characteristics. Threshold-based measures provided modest performance, the greatest area under the curve (AUC) being 0.70. Global strain parameters exhibited reduced performance, with AUC under 0.64. A neural network trained exclusively from 3D-MDA data achieved an AUC of 0.94 (sensitivity 0.92, specificity 0.90) when performing the same task. This study demonstrates that ML-based diagnosis of cardiomyopathy states performed exclusively from 3D-MDA is feasible and can distinguish HCM from mimic disease states. These findings suggest strong potential for computer-assisted diagnosis in clinical practice.

Regional Right Ventricular Abnormalities Implicate Distinct Pathophysiological Conditions in Patients With Chronic Thromboembolic Pulmonary Hypertension

Background

Right ventricular (RV) dysfunction is a prognostic factor for cardiovascular disease. However, its mechanism and pathophysiology remain unknown. We investigated RV function using RV‐specific 3‐dimensional (3D)‐speckle‐tracking echocardiography (STE) in patients with chronic thromboembolic pulmonary hypertension. We also assessed regional wall motion abnormalities in the RV and chronological changes during balloon pulmonary angioplasty (BPA).

Methods and Results

Twenty‐nine patients with chronic thromboembolic pulmonary hypertension who underwent BPA were enrolled and underwent right heart catheterization and echocardiography before, immediately after, and 6 months after BPA. Echocardiographic assessment of RV function included both 2‐dimensional‐STE and RV‐specific 3D‐STE. Before BPA, global area change ratio measured by 3D‐STE was significantly associated with invasively measured mean pulmonary artery pressure and pulmonary vascular resistance (r=0.671 and r=0.700, respectively). Dividing the RV into the inlet, apex, and outlet, inlet area change ratio showed strong correlation with mean pulmonary artery pressure and pulmonary vascular resistance before BPA (r=0.573 and r=0.666, respectively). Only outlet area change ratio was significantly correlated with troponin T values at 6 months after BPA (r=0.470), and its improvement after BPA was delayed compared with the inlet and apex regions. Patients with poor outlet area change ratio were associated with a delay in RV reverse remodeling after treatment.

Conclusions

RV‐specific 3D‐STE analysis revealed that 3D RV parameters were novel useful indicators for assessing RV function and hemodynamics in pulmonary hypertension and that each regional RV portion presents a unique response to hemodynamic changes during treatment, implicating that evaluation of RV regional functions might lead to a new guide for treatment strategies.

Comparison of the capability of risk stratification evaluation between two- and three-dimensional speckle-tracking strain in pre-capillary pulmonary hypertension

To investigate and compare the value of right ventricular longitudinal strain detected by two-dimensional and three-dimensional speckle-tracking echocardiography in risk stratification evaluation in pre-capillary pulmonary hypertension. We consecutively screened 66 patients diagnosed with pre-capillary pulmonary hypertension in our center. According to the risk assessment recommended by 2015 European Society of Cardiology Guidelines, all participants were classified into low- and intermediate-high-risk group. Two-dimensional and three-dimensional strains were measured using off-line softwares (GE EchoPAC version 201 and TomTec, 4D RV Function 2.0). Fifty-seven pre-capillary pulmonary hypertension patients (average 35 years old, 18 males and 39 females) were finally enrolled in our study, 32 (56.1%) were classified in low-risk group, while 25 (43.9%) were in the intermediate-high-risk group. Clinical data associated with disease severity, such as N-terminal pro-brain natriuretic peptide (r = 0.574, P < 0.001), peak oxygen consumption (r = -0.484, P < 0.001), and 6-min walking distance (r = -0.356, P = 0.008) were significantly correlated with two-dimensional right ventricular longitudinal strain; while the correlations with three-dimensional right ventricular longitudinal strain were weaker. Receiver operating characteristic curves for the detection of intermediate-high risk stratification showed two-dimensional right ventricular longitudinal strain had the best predictive capacity (area under curve, 0.82, 95% CI: 0.71-0.93, P < 0.001). Univariate and Multivariate Logistic regression analyses identified two-dimensional right ventricular longitudinal strain as an independent predictor (OR: 1.42, 95% CI: 1.18-1.71, P < 0.001) of intermediate-high risk stratification in this cohort of pre-capillary pulmonary hypertension patients, the predictive capacity retained (OR: 1.45, 95% CI: 1.18-1.78, P < 0.001) after adjusted by age, gender, and body mass index, while three-dimensional speckle-tracking echocardiography parameters were not. In conclusion, when used for the detection of intermediate-high risk stratification in pre-capillary pulmonary hypertension, two-dimensional right ventricular longitudinal strain was better than three-dimensional right ventricular longitudinal strain.

Should the septum be included in the assessment of right ventricular longitudinal strain? An ultrasound two-dimensional speckle-tracking stress study

Right ventricular longitudinal strain (RVLS) by 2D speckle-tracking echocardiography (2D-STE) is a useful parameter for assessing systolic function. However, the exact method to perform it is not well defined as some authors evaluate only free wall (FW) segments while others include all six RV segments. To compare the assessment of RVLS at rest and during exercise by these two approaches. Echocardiography was performed on 80 healthy subjects at rest and during exercise. The analysis consisted of standard and 2D-STE assessment of RV global and segmental strain tracing only RVFW and also tracing all six RV segments. At rest, RVLS could be assessed in 78 (feasibility 97.5%) subjects by both methods. However, during exercise, RVLS by RVFW method was feasible in 67 (83.8%) as compared to 74 (92.5%) by RV6S approach. Both at rest and during exercise, RVLS values by the two methods showed excellent correlation (r =  > 0.90). However, RVLS values assessed by RV6S were lower (absolute values) than those by RVFW approach (RV6S vs. RVFW; rest: - 27.0 ± 3.9 vs. - 9.5 ± 3.9, p < 0.001 and exercise: - 30.7 ± 5.2 vs. - 33.3 ± 5.1, p < 0.001). Furthermore, basal strain was higher and apical strain lower (absolute values) by RV6S approach. At rest, reproducibility for RVLS was excellent and similar for the two methods. However, during exercise, reproducibility for RVFW method was poorer, especially at the apex. The two currently described methods for RVLS assessment by 2D-STE demonstrated excellent agreement. However, the RV6S approach seemed to be more feasible and reproducible, particularly during exercise. Moreover, global and segmental strain values are different with both methods and should not be interchanged.