Three-dimensional echocardiography and 2D-3D speckle tracking imaging in chronic pulmonary hypertension. diagnostic accuracy in detecting hemodynamic signs of RV failure

Background and objective. Our aim was to compare three-dimensional (3D) and 2D and 3D speckle tracking (2D-STE, 3D-STE) echocardiographic parameters with conventional right ventricular (RV) indexes in patients with chronic pulmonary hypertension (PH), and investigate whether these techniques could result in better correlation with hemodynamic variables indicative of heart failure. Methods. Seventy-three adult patients (mean age, 53±13 years; 44% male) with chronic PH of different etiologies were studied by echocardiography and cardiac catheterization (25 precapillary PH from pulmonary arterial hypertension, 23 obstructive pulmonary heart disease, and 23 postcapillary PH from mitral regurgitation). Thirty healthy subjects (mean age, 54±15 years; 43% male) served as controls. Standard 2D measurements (RV-FAC -fractional area change-, TAPSE -tricuspid annular plane systolic excursion-) and mitral and tricuspid tissue Doppler annular velocities were obtained. RV 3D volumes, and global and regional ejection fraction (3D-RVEF) were determined. RV strains were calculated by 2D-STE and 3D-STE. Results. RV 3D global-free-wall longitudinal strain (3DGFW-RVLS), 2D global-free-wall longitudinal strain (GFW-RVLS), apical-free-wall longitudinal strain (AFW-RVLS), basal-free-wall longitudinal strain (BFW-RVLS), and 3D-RVEF were lower in patients with pre-capillary PH (p<0.0001) and post-capillary PH (p<0.01) compared to controls. 3DGFW-RVLS (HR 4.6, 95% CI 2.79-8.38, p=0.004) and 3D-RVEF (HR 5.3, 95% CI 2.85-9.89, p=0.002) were independent predictors of mortality. ROC curves showed that the thresholds offering an adequate compromise between sensitivity and specificity for detecting hemodynamic signs of RV failure were 39% for 3D-RVEF (AUC 0.89), -17% for 3DGFW-RVLS (AUC 0.88), -18% for GFW-RVLS (AUC 0.88), -16% for AFW-RVLS (AUC 0.85), 16mm for TAPSE (AUC 0.67), and 38% for RV-FAC (AUC 0.62). Conclusions. In chronic PH, 3D, 2D-STE and 3D-STE parameters indicate global and regional RV dysfunction that is associated with RV failure hemodynamics better than conventional echo indices

Advances in computational modelling for personalised medicine after myocardial infarction

Myocardial infarction (MI) is a leading cause of premature morbidity and mortality worldwide. Determining which patients will experience heart failure and sudden cardiac death after an acute MI is notoriously difficult for clinicians. The extent of heart damage after an acute MI is informed by cardiac imaging, typically using echocardiography or sometimes, cardiac magnetic resonance (CMR). These scans provide complex data sets that are only partially exploited by clinicians in daily practice, implying potential for improved risk assessment. Computational modelling of left ventricular (LV) function can bridge the gap towards personalised medicine using cardiac imaging in patients with post-MI. Several novel biomechanical parameters have theoretical prognostic value and may be useful to reflect the biomechanical effects of novel preventive therapy for adverse remodelling post-MI. These parameters include myocardial contractility (regional and global), stiffness and stress. Further, the parameters can be delineated spatially to correspond with infarct pathology and the remote zone. While these parameters hold promise, there are challenges for translating MI modelling into clinical practice, including model uncertainty, validation and verification, as well as time-efficient processing. More research is needed to (1) simplify imaging with CMR in patients with post-MI, while preserving diagnostic accuracy and patient tolerance (2) to assess and validate novel biomechanical parameters against established prognostic biomarkers, such as LV ejection fraction and infarct size. Accessible software packages with minimal user interaction are also needed. Translating benefits to patients will be achieved through a multidisciplinary approach including clinicians, mathematicians, statisticians and industry partners

Magnetic resonance imaging of myocardial strain after acute ST-segment-elevation myocardial infarction: a systematic review

The purpose of this systematic review is to provide a clinically relevant, disease-based perspective on myocardial strain imaging in patients with acute myocardial infarction or stable ischemic heart disease. Cardiac magnetic resonance imaging uniquely integrates myocardial function with pathology. Therefore, this review focuses on strain imaging with cardiac magnetic resonance. We have specifically considered the relationships between left ventricular (LV) strain, infarct pathologies, and their associations with prognosis. A comprehensive literature review was conducted in accordance with the PRISMA guidelines. Publications were identified that (1) described the relationship between strain and infarct pathologies, (2) assessed the relationship between strain and subsequent LV outcomes, and (3) assessed the relationship between strain and health outcomes. In patients with acute myocardial infarction, circumferential strain predicts the recovery of LV systolic function in the longer term. The prognostic value of longitudinal strain is less certain. Strain differentiates between infarcted versus noninfarcted myocardium, even in patients with stable ischemic heart disease with preserved LV ejection fraction. Strain recovery is impaired in infarcted segments with intramyocardial hemorrhage or microvascular obstruction. There are practical limitations to measuring strain with cardiac magnetic resonance in the acute setting, and knowledge gaps, including the lack of data showing incremental value in clinical practice. Critically, studies of cardiac magnetic resonance strain imaging in patients with ischemic heart disease have been limited by sample size and design. Strain imaging has potential as a tool to assess for early or subclinical changes in LV function, and strain is now being included as a surrogate measure of outcome in therapeutic trials

Cardiovascular Magnetic Resonance Deformation Imaging By Feature Tracking For Assessment Of Left And Right Ventricular Structure And Function

The copyright of this thesis rests with the author and no quotation from it or information derived from it may be published without the prior written consent of the authorCardiac magnetic resonance (CMR) imaging is the gold standard imaging technique for assessment of ventricular dimensions and function. CMR also allows assessment of ventricular deformation but this requires additional imaging sequences and time consuming post processing which has limited its widespread use. A novel CMR analysis software package, ‘feature tracking’ (Tom Tec, Germany) can measure ventricular deformation directly from cine CMR images. This thesis seeks to further our understanding of the feasibility of feature tracking to assess myocardial deformation and volumetric measures. Chapter 3 validates normal ranges for deformation parameters and compares values against traditional tagging measures. The work identifies global circumferential strain measures as being the most reproducible. In chapters 4 and 5, feature tracking values for left and right ventricular strain are compared with echocardiography derived speckle tracking indices of deformation. For left ventricular (LV) parameters, circumferential and longitudinal strain are most consistent and for the right ventricular (RV) measures, assessment of free wall strain using feature tracking shows promise and with modifications in algorithms is likely to further improve in the future. Chapter 6 assesses the ability of feature tracking to measure diastolic function. The results show that radial diastolic velocities and longitudinal diastolic strain rates can predict diastolic dysfunction (as diagnosed by echocardiography) with acceptable levels of sensitivity and specificity, particularly when used in combination. 11 The use of feature tracking to provide automated measures of ventricular volumes, mass and ejection fraction is assessed in chapter 7. Feature tracking in this context shows acceptable correlation but poor absolute agreement with manual contouring and further adjustments to algorithms is necessary to improve its accuracy. This work offers insights into the use of feature tracking for the assessment of ventricular deformation parameters. It is a technique with advantages over CMR tagging methods and given the speed of post processing has the potential to become the CMR preferred assessment for strain quantification in the future.I am indebted to the Engineering and Physical Sciences Research Council, the British Heart Foundation and the National Institute for Health Research Oxford Biomedical Research Centre for funding this work

Left atrial trajectory impairment in hypertrophic cardiomyopathy disclosed by geometric morphometrics and parallel transport

The analysis of full Left Atrium (LA) deformation and whole LA deformational trajectory in time has been poorly investigated and, to the best of our knowledge, seldom discussed in patients with Hypertrophic Cardiomyopathy. Therefore, we considered 22 patients with Hypertrophic Cardiomyopathy (HCM) and 46 healthy subjects, investigated them by three-dimensional Speckle Tracking Echocardiography, and studied the derived landmark clouds via Geometric Morphometrics with Parallel Transport. Trajectory shape and trajectory size were different in Controls versus HCM and their classification powers had high AUC (Area Under the Receiving Operator Characteristic Curve) and accuracy. The two trajectories were much different at the transition between LA conduit and booster pump functions. Full shape and deformation analyses with trajectory analysis enabled a straightforward perception of pathophysiological consequences of HCM condition on LA functioning. It might be worthwhile to apply these techniques to look for novel pathophysiological approaches that may better define atrio-ventricular interaction

Speckle-Tracking Imaging, Principles and Clinical Applications: A Review for Clinical Cardiologists

Evaluation of myocardial mechanics, although complex, has now entered the clinical arena, thanks to the introduction of bedside imaging techniques, such as speckle-tracking echocardiography

Robust Cardiac Motion Estimation using Ultrafast Ultrasound Data: A Low-Rank-Topology-Preserving Approach

Cardiac motion estimation is an important diagnostic tool to detect heart diseases and it has been explored with modalities such as MRI and conventional ultrasound (US) sequences. US cardiac motion estimation still presents challenges because of the complex motion patterns and the presence of noise. In this work, we propose a novel approach to estimate the cardiac motion using ultrafast ultrasound data. -- Our solution is based on a variational formulation characterized by the L2-regularized class. The displacement is represented by a lattice of b-splines and we ensure robustness by applying a maximum likelihood type estimator. While this is an important part of our solution, the main highlight of this paper is to combine a low-rank data representation with topology preservation. Low-rank data representation (achieved by finding the k-dominant singular values of a Casorati Matrix arranged from the data sequence) speeds up the global solution and achieves noise reduction. On the other hand, topology preservation (achieved by monitoring the Jacobian determinant) allows to radically rule out distortions while carefully controlling the size of allowed expansions and contractions. Our variational approach is carried out on a realistic dataset as well as on a simulated one. We demonstrate how our proposed variational solution deals with complex deformations through careful numerical experiments. While maintaining the accuracy of the solution, the low-rank preprocessing is shown to speed up the convergence of the variational problem. Beyond cardiac motion estimation, our approach is promising for the analysis of other organs that experience motion.Comment: 15 pages, 10 figures, Physics in Medicine and Biology, 201

Left ventricular remodeling and function in ischemic heart disease and aortic valve disease

Background: Cardiac remodeling is a broad term that refers to structural and functional alterations of the heart in response to chronic changes in loading conditions or left ventricular (LV) contractile performance. Different loading conditions will affect the heart in different ways, some leading to impaired heart function, symptoms of heart failure, or even death. However, the process of remodeling may not be permanent. If the heart is relieved of the underlying cause of the remodeling, the heart function and structure may normalize in a process referred to as reverse remodeling. The complex interplay of factors that determine the process of reverse remodeling is not fully elucidated. Cardiac remodeling can be evaluated by many different diagnostic modalities, but the most widely used diagnostic tool is two-dimensional echocardiography (2DE). In recent years, three-dimensional echocardiography (3DE) has emerged with possible advantages in the assessment of LV volume and function. The thesis aimed to evaluate 3DE in the assessment of LV function and remodeling, and to study different aspects of remodeling in response to pressure and volume overload in patients with aortic stenosis (AS) and aortic regurgitation (AR), respectively. Methods: Studies I and II investigated patients with ischemic heart disease (n = 15 and n = 32, respectively). In Study I, the assessments of LV volume and ejection fraction (EF) were compared using 3DE, cardiac magnetic resonance (CMR), and single-photon emission computer tomography (SPECT). Study II compared the performance of 2DE, contrast-enhanced 2DE, 3DE, and contrast-enhanced 3DE in the assessment LV volumes and EF, using CMR as a reference standard. In Studies III and IV, 65 patients with severe AR and 120 patients with severe AS, respectively, were examined using 2DE and 3DE before and at one year after aortic valve replacement (AVR). In Study III, LV volumes, systolic and diastolic LV function, and left atrial strain (LAS) were analyzed to identify predictors of impaired LV reverse remodeling in AR. Study IV assessed LV functional indices, including 2D global longitudinal strain (GLS) and 3D strain, to assess predictors of incomplete reverse remodeling in AS. Results and conclusions: There were significant differences among 3DE, SPECT and CMR regarding the measurement of LV volumes. However, the estimation of EF showed good agreement. 3DE was more accurate and showed more favorable reproducibility than 2DE for the assessment of EF and LV volumes. Contrast enhancement improved accuracy and reproducibility for both 2DE and 3DE. One-third of patients with AR had signs of impaired LV diastolic function. After AVR, diastolic LV functional indices improved, LV and left atrial (LA) volumes decreased, and indices of LA function increased. LA conduit strain had an incremental prognostic value for the prediction of impaired LV functional and structural recovery. In patients with AS, AVR was associated with a decrease in LV mass, an improvement in 2D GLS, and a decrease in LV twist. 2D GLS and left ventricular mass index were predictive of incomplete reverse remodeling during the follow-up period. 3D GLS did not add discriminatory or predictive information over 2D GLS