Application of strain echocardiography in valvular heart diseases

Clinical Outcomes and Echocardiographic Predictors of Reintervention After Interrupted Aortic Arch Repair

Left ventricular outflow tract obstruction (LVOTO) remains a significant complication after primary repair of interrupted aortic arch with ventricular septal defect (IAA-VSD). Clinical and echocardiographic predictors for LVOTO reoperation are controversial and procedures to prophylactically prevent future LVOTO are not reliable. However, it is important to identify the patients at risk for future LVOTO intervention after repair of IAA-VSD. Patients who underwent single-stage IAA-VSD repair at our center 2006-2021 were retrospectively reviewed, excluding patients with associated cardiac lesions. Two-dimensional measurements, LVOT gradients, and 4-chamber (4C) and short-axis (SAXM) strain were obtained from preoperative and predischarge echocardiograms. Univariate risk analysis for LVOTO reoperation was performed using unpaired t-test. Thirty patients were included with 21 (70%) IAA subtype B and mean weight at surgery 3.0 kg. Repair included aortic arch patch augmentation in 20 patients and subaortic obstruction intervention in three patients. Seven (23%) required reoperations for LVOTO. Patient characteristics were similar between patients who required LVOT reoperation and those who did not. Patch augmentation was not associated with LVOTO reintervention. Patients requiring reintervention had significantly smaller LVOT AP diameter preoperatively and at discharge, and higher LVOT velocity, smaller AV annular diameter, and ascending aortic diameter at discharge. There was an association between LVOT-indexed cross-sectional area (CSAcm2/BSAm2) ≤ 0.7 and reintervention. There was no significant difference in 4C or SAXM strain in patients requiring reintervention. LVOTO reoperation was not associated with preoperative clinical or surgical variables but was associated with smaller LVOT on preoperative echo and smaller LVOT, smaller AV annular diameter, and increased LVOT velocity at discharge.

Echocardiographic Parameters and Complication Profiles Among Adult Patients with Rheumatic Heart Disease at Jimma Medical Center

Background

Despite the fact that patients with rheumatic heart disease (RHD) need early medical attention and follow-up, most patients in developing countries tend to present with debilitating complications. The objective of this study was to evaluate the echocardiographic features of adult individuals diagnosed with RHD and examine the associated complications among patients who started follow-up at Jimma Medical Center's (JMC) cardiac follow-up clinic.

Methods

A prospective cross-sectional study was conducted at JMC between January 5 and April 15, 2023. Echocardiographic patterns were taken by senior cardiologists; socio-demographic variables, anthropometric measurements, and behavioral factors were collected through a structured questioner.

Results

The study recruited a total of 115 participants, of whom 86 (74.8%) were female and 29 (25.2%) were male. The mean age of the patients was 32.31 (SD± 12.16) years. The mitral valve was affected in 98.26% of cases, while the aortic and tricuspid valve abnormalities were diagnosed in 49.5% and 21.7%, respectively. The most frequent combinations of valve lesions were mitral regurgitation (MR) + mitral stenosis (MS) + aortic regurgitation (AR) (15.7%), followed by MR + AR + TR (8.7%). The occurrence of MR+MS+AR was higher in females (17.4%) compared to males (10.3%), whereas the occurrence of MS+MR was higher in males (24.1%) compared to females (20.9%). Females have a severely reduced ejection fraction compared to males (84.8% vs 15.2%, P = 0.044). Nearly two-thirds (63.5%) of individuals experienced RHD-related complications; the most commonly encountered complications were pulmonary hypertension (26.1%) and atrial fibrillation (19.1%).

Conclusion

RHD predominantly affects individuals in their active and productive years, particularly females. Most patients have multiple-valve lesions.

Myocardial strain of the left ventricle by speckle tracking echocardiography: From physics to clinical practice

Speckle tracking echocardiography (STE) is a reliable imaging technique of recognized clinical value in several settings. This method uses the motion of ultrasound backscatter speckles within echocardiographic images to derive myocardial velocities and deformation parameters, providing crucial insights on several cardiac pathological and physiological processes. Its feasibility, reproducibility, and accuracy have been widely demonstrated, being myocardial strain of the various chambers inserted in diagnostic algorithms and guidelines for various pathologies. The most important parameters are Global longitudinal strain (GLS), Left atrium (LA) reservoir strain, and Global Work Index (GWI): based on large studies the average of the lower limit of normality are -16%, 23%, and 1442 mmHg%, respectively. For GWI, it should be pointed out that myocardial work relies primarily on non-invasive measurements of blood pressure and segmental strain, both of which exhibit high variability, and thus, this variability constitutes a significant limitation of this parameter. In this review, we describe the principal aspects of the theory behind the use of myocardial strain, from cardiac mechanics to image acquisition techniques, outlining its limitation, and its principal clinical applications: in particular, GLS have a role in determine subclinical myocardial dysfunction (in cardiomyopathies, cardiotoxicity, target organ damage in ambulatory patients with arterial hypertension) and LA strain in determine the risk of AF, specifically in ambulatory patients with arterial hypertension.

Current and novel echocardiographic assessment of left ventricular systolic function in aortic stenosis-A comprehensive review

Aortic stenosis (AS) is a complex and progressive condition that can significantly reduce the quality of life and increase the incidence of premature mortality. Transthoracic echocardiography (TTE) is the gold standard imaging modality for the assessment of AS severity. While left ventricular ejection fraction (LVEF) derived from TTE is a very well-understood parameter, limitations such as high inter and intra-observer variability, insensitivity to sub-clinical dysfunction, and influence of loading conditions make LVEF a complicated and unreliable parameter. Myocardial deformation imaging has been identified as a promising parameter for identifying subclinical left ventricular dysfunction, however, this parameter is still afterload dependent. Myocardial Work is a promising novel assessment technique that accounts for afterload by combining the use of myocardial deformation imaging and non-invasive blood pressure to provide a more comprehensive assessment of mechanics beyond LVEF. This review evaluates the evidence for various echocardiographic assessment parameters used to quantify left ventricular function including myocardial work in patients with AS.

Molecular Approaches and Echocardiographic Deformation Imaging in Detecting Myocardial Fibrosis

The pathological remodeling of myocardial tissue is the main cause of heart diseases. Several processes are involved in the onset of heart failure, and the comprehension of the mechanisms underlying the pathological phenotype deserves special attention to find novel procedures to identify the site of injury and develop novel strategies, as well as molecular druggable pathways, to counteract the high degree of morbidity associated with it. Myocardial fibrosis (MF) is recognized as a critical trigger for disruption of heart functionality due to the excessive accumulation of extracellular matrix proteins, in response to an injury. Its diagnosis remains focalized on invasive techniques, such as endomyocardial biopsy (EMB), or may be noninvasively detected by cardiac magnetic resonance imaging (CMRI). The detection of MF by non-canonical markers remains a challenge in clinical practice. During the last two decades, two-dimensional (2D) speckle tracking echocardiography (STE) has emerged as a new non-invasive imaging modality, able to detect myocardial tissue abnormalities without specifying the causes of the underlying histopathological changes. In this review, we highlighted the clinical utility of 2D-STE deformation imaging for tissue characterization, and its main technical limitations and criticisms. Moreover, we focalized on the importance of coupling 2D-STE examination with the molecular approaches in the clinical decision-making processes, in particular when the 2D-STE does not reflect myocardial dysfunction directly. We also attempted to examine the roles of epigenetic markers of MF and hypothesized microRNA-based mechanisms aiming to understand how they match with the clinical utility of echocardiographic deformation imaging for tissue characterization and MF assessment.

Layer-specific longitudinal strain detects transmural dysfunction in chronic severe aortic regurgitation before and after aortic valve surgery

To assess if layer-specific longitudinal strain (LS) provides incremental diagnostic and prognostic value compared to global longitudinal strain (GLS) in patients with chronic severe aortic regurgitation (AR) scheduled for aortic valve surgery. Forty-one patients were examined with speckle tracking echocardiography before surgery along with 15 healthy age-matched controls. Paired strain analyses before and after surgery were available in 31 patients. Layer-specific LS analysis enabled assessment of epicardial GLS (GLSepi), endocardial GLS (GLSendo), and conventional GLS. Strain parameters were indexed to end-diastolic volume (EDV; GLS/EDV) to account for increased preload. The prognostic value of layer-specific LS was evaluated using the primary outcome of persistent LV dilatation (LVEDV ≥ 175 mL) three months after surgery. Absolute (GLS, GLSepi, GLSendo) and EDV-indexed layer-specific LS (GLS/EDV, GLSepi/EDV, GLSendo/EDV) were impaired in severe AR compared to controls at baseline (GLS:17.0 ± 3.2 vs. 20.6 ± 2.0; GLSepi:14.6 ± 2.8 vs. 18.1 ± 1.9; GLSendo:20.2 ± 3.7 vs. 23.8 ± 2.2%; GLS/EDV:0.09 ± 0.05 vs. 0.21 ± 0.05; GLSepi/EDV:0.08 ± 0.04 vs. 0.18 ± 0.04; GLSendo/EDV:0.11 ± 0.06 vs. 0.24 ± 0.05%/mL; all p < 0.001). In severe AR, GLS, GLSepi and GLSendo decreased after surgery whereas GLS/EDV, GLSepi/EDV and GLSendo/EDV increased (all p < 0.001). Impaired absolute and EDV-indexed layer-specific LS were all associated with the primary outcome (all p ≤ 0.01). Area under the curve analysis revealed similar prognostic value of GLSepi, GLSendo and GLS (GLS:0.86; GLSepi:0.87; GLSendo:0.86; p = n.s.). EDV-indexed LS did not improve the predictive value significantly (GLS/EDV:0.93; GLSepi/EDV: 0.93; GLSendo/EDV:0.92; p = n.s.). Layer-specific LS detects transmural dysfunction in chronic severe AR and predicts persistent LV dilation after surgery. Layer-specific LS or EDV-indexed LS does not provide incremental prognostic value compared to conventional GLS.

Prognostic value of myocardial work and global longitudinal strain in patients with heart failure and functional mitral regurgitation

In patients with heart failure and functional mitral regurgitation (FMR), the assessment of left ventricular (LV) function is important for risk stratification and decision making. As LV ejection fraction (LVEF) might not be an optimal metric for LV systolic performance in this population, alternatives such as global longitudinal strain (GLS) and global myocardial work index (GWI) have been proposed. In the present study, we investigated the prognostic value of GLS and GWI and compared these measures to other LV systolic performance parameters. A prospective and consecutive cohort of 181 patients (median age 72 years, 76% male) with LVEF < 50% and FMR underwent comprehensive echocardiographic examination including speckle tracking echocardiography and grading of FMR severity. During a median follow-up of 42 months, 72 cardiovascular (CV) events occurred. In univariate analysis, LVEF, GLS, GWI, mitral S', LV outflow tract time velocity integral, forward LVEF and LV ejection time were associated with CV events. After multivariate adjustment only GLS (hazard ratio (HR) = 0.884, p = 0.015) and GWI (HR = 0.927, p = 0.034) remained independently associated with CV events. There was no difference in the incremental prognostic value of GWI compared to GLS (delta -2 log likelihood = 0.8; p = 0.37). In this cohort of heart failure patients with FMR, GLS and GWI were independently associated with cardiovascular events, whereas other systolic performance parameters were not. However, GWI did not outperform GLS, and further research is required to determine the value of these strain-based measures in clinical practice.

Assessment of Biventricular Myocardial Function with 2-Dimensional Strain and Conventional Echocardiographic Parameters: A Comparative Analysis in Healthy Infants and Patients with Severe and Critical Pulmonary Stenosis

Our aim was to compare the global longitudinal and regional biventricular strain between infants with severe and critical pulmonary stenosis (PS), and controls; to compare pre- and post-procedural strain values in infants with severe and critical PS; and to assess the correlations between echocardiographic strain and conventional parameters. We conducted a retrospective single-center study. The comparisons of echocardiographic variables were performed using separate linear mixed models. The overall mean right ventricle (RV) regional strains measured before intervention in PS patients was significantly different when compared to the control group (p = 0.0324). We found a significant change in the left ventricle, RV, and inter-ventricular septum strain (IVS) values from basal to apical location (p < 0.05). IVS strain values showed a higher decrease in mean strain values from basal to apical in PS patients. There was no significant difference in means of baseline and post-interventional strain values in PS patients (p > 0.05). Following the strain analysis in patients with PS, we obtained statistically significant changes in the RV global-4-chamber longitudinal strain (RV4C). The RV4C, which quantifies the longitudinal strain to the entire RV, can be used in current clinical practice for the evaluation of RV function in infants with severe and critical PS. The longitudinal and segmental strain capture the pathological changes in the IVS, modifications that cannot be highlighted through a classical echocardiographic evaluation.

The strain and strain rate imaging paradox in echocardiography: overabundant literature in the last two decades but still uncertain clinical utility in an individual case

Almost two decades ago strain and strain rate imaging were proposed as a new, potentially more sensitive modality for quantifying both regional and global myocardial function. Until now, however, strain and strain rate imaging have been slow to be incorporated into everyday clinical practice. More recently, two dimensional strain has been claimed as of greater clinical utility, given that it is angle independent, with improved feasibility and reproducibility as compared to tissue Doppler strain. Nevertheless, speckle tracking strain is reliant on 2D image quality and frame rates. Three dimensional speckle tracking could eliminate the problem of through-plane motion inherent in 2D imaging, but 3D strain is currently limited by low frame rates. Another limitation of strain imaging is that the results are dependent on the ultrasound machine on which analyses are performed, with variability in measurements between different vendors. Despite the diagnostic and prognostic advantages of 2D strain, there is a lack of specific therapeutic interventions based on strain and a paucity of long-term large-scale randomized trial evidence on cardiovascular outcomes. After overabundant literature the same definition of normal cut-off values is controversial and not univocal. Further studies are needed, involving both manufacturers and medical professionals, on the additive contribution, possibly different case by case, of interfering and artifactual factors, aside from myocardial function per se. These artifactual determinants and motion artifacts components could be dominant in individual cases and should always be taken into account in the clinical decision making process in a single case.