Strain, Strain Rate, Torsion, and Twist: Echocardiographic Evaluation

Assessment of new-onset heart failure prediction in a diabetic population using left ventricular global strain: a prospective cohort study based on UK Biobank

Background

Impaired glucose utilization influences myocardial contractile function. However, the prognostic importance of left ventricular global radial strain (LV-GRS), left ventricular global circumferential strain (LV-GCS), and left ventricular global longitudinal strain (LV-GLS) in predicting new-onset heart failure (HF) in a population with diabetes is unclear.

Methods

The study design is prospective cohort from the UK Biobank. Totally 37,899 participants had a complete data of cardiac magnetic resonance (CMR), of which 940 patients with diabetes were included, and all the participants completed follow-up. LV-GRS, LV-GCS, and LV-GLS were measured by completely automated CMR with tissue tagging. Cox proportional hazards regression analysis and C-index was performed to evaluate the association between the strain parameters and the new-onset HF in patients suffering from diabetes.

Results

The average age of the 940 participants was 57.67 ± 6.97 years, with males comprising 66.4% of the overall population. With an average follow-up period of 166.82 ± 15.26 months, 35 (3.72%) patients reached the endpoint (emergence of new-onset HF). Significant associations were found for the three strain parameters and the new-onset HF (LV-GRS-hazard ratio [HR]: 0.946, 95% CI: 0.916-0.976; LV-GCS-HR: 1.162, 95% CI: 1.086-1.244; LV-GCS-HR: 1.181, 95% CI: 1.082-1.289). LV-GRS, LV-GCS, and LV-GLS were closely related to the related indicators to HF, and showed a high relationship to new-onset HF in individuals with diabetes at 5 and 10 years: LV-GRS: 0.75 (95% CI, 0.41-0.94) and 0.76 (95% CI, 0.44-0.98), respectively; LV-GCS: 0.80 (95% CI, 0.50-0.96) and 0.75 (95% CI, 0.41-0.98), respectively; LV-GLS: 0.72 (95% CI, 0.40-0.93) and 0.76 (95% CI, 0.48-0.97), respectively. In addition, age, sex, body mass index (BMI), and presence of hypertension or coronary artery disease (CAD) made no impacts on the association between the global strain parameters and the incidence of HF.

Conclusion

LV-GRS, LV-GCS, and LV-GLS is significantly related to new-onset HF in patients with diabetes at 5 and 10 years.

Prognostic Value of Left Ventricular Longitudinal Function and Myocardial Fibrosis in Patients With Ischemic and Non-Ischemic Dilated Cardiomyopathy Concomitant With Type 2 Diabetes Mellitus: A 3.0 T Cardiac MR Study

BACKGROUND

Poorly controlled type 2 diabetes mellitus (T2DM) is known to result in left ventricular (LV) dysfunction, myocardial fibrosis, and ischemic/nonischemic dilated cardiomyopathy (ICM/NIDCM). However, less is known about the prognostic value of T2DM on LV longitudinal function and late gadolinium enhancement (LGE) assessed with cardiac MRI in ICM/NIDCM patients.

PURPOSE

To measure LV longitudinal function and myocardial scar in ICM/NIDCM patients with T2DM and to determine their prognostic values.

STUDY TYPE

Retrospective cohort.

POPULATION

Two hundred thirty-five ICM/NIDCM patients (158 with T2DM and 77 without T2DM).

FIELD STRENGTH/SEQUENCE

3T; steady-state free precession cine; phase-sensitive inversion recovery segmented gradient echo LGE sequences.

ASSESSMENT

Global peak longitudinal systolic strain rate (GLPSSR) was evaluated to LV longitudinal function with feature tracking. The predictive value of GLPSSR was determined with ROC curve. Glycated hemoglobin (HbA1c) was measured. The primary adverse cardiovascular endpoint was follow up every 3 months.

STATISTICAL TESTS

Mann-Whitney U test or student's t-test; Intra and inter-observer variabilities; Kaplan-Meier method; Cox proportional hazards analysis (threshold = 5%).

RESULTS

ICM/NIDCM patients with T2DM exhibited significantly lower absolute value of GLPSSR (0.39 ± 0.14 vs. 0.49 ± 0.18) and higher proportion of LGE positive (+) despite similar LV ejection fraction, compared to without T2DM. LV GLPSSR was able to predict primary endpoint (AUC 0.73) and optimal cutoff point was 0.4. ICM/NIDCM patients with T2DM (GLPSSR < 0.4) had more markedly impaired survival. Importantly, this group (GLPSSR < 0.4, HbA1c ≥ 7.8%, or LGE (+)) exhibited the worst survival. In multivariate analysis, GLPSSR, HbA1c, and LGE (+) significantly predicted primary adverse cardiovascular endpoint in overall ICM/NIDCM and ICM/NIDCM patients with T2DM.

CONCLUSIONS

T2DM has an additive deleterious effect on LV longitudinal function and myocardial fibrosis in ICM/NIDCM patients. Combining GLPSSR, HbA1c, and LGE could be promising markers in predicting outcomes in ICM/NIDCM patients with T2DM.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: 5.

Application of Speckle Tracking Echocardiography for Evaluating Ventricular Function after Transcatheter Pulmonary Valve Replacement

Pulmonary regurgitation usually leads to right heart dilatation and eventually right heart dysfunction, which is associated with a poor prognosis. Transcatheter pulmonary valve replacement is a developing treatment for pulmonary valve dysfunction that can take the place of traditional surgery and make up for the shortcomings of a large injury. Echocardiography plays a significant role in assessing ventricular function; however, conventional echocardiographic parameters have several limitations. Speckle tracking echocardiography has been regarded as a more accurate tool for quantifying cardiac function than conventional echocardiography. Therefore, the aim of this review was to summarize the application of speckle tracking echocardiography for evaluating right and left ventricular functions in patients after transcatheter pulmonary valve replacement.

Imaging in atrial fibrillation: A way to assess atrial fibrosis and remodeling to assist decision-making

The 2020 ESC atrial fibrillation (AF) guidelines suggest the novel 4S-AF scheme for the characterization of AF. Imaging techniques could be helpful for this objective in everyday clinical practice, and information derived from these techniques reflects basic aspects of the pathophysiology of AF, which may facilitate treatment decision-making, and optimal management of AF patients. The aim of this review is to provide an overview of the mechanisms associated with atrial fibrosis and to describe imaging techniques that may help the management of AF patients in clinical practice. Transthoracic echocardiography is the most common procedure given its versatility, safety, and simplicity. Transesophageal echocardiography provides higher resolution exploration, and speckle tracking echocardiography can provide incremental functional and prognostic information over conventional echocardiographic parameters. In addition, LA deformation imaging, including LA strain and strain rate, are related to the extent of fibrosis. On the other hand, multidetector-row computed tomography and cardiac magnetic resonance provide higher resolution data and more accurate assessment of the dimensions, structure, and spatial relationships of the LA. Imaging is central when deciding on catheter ablation or cardioversion, and helps in selecting those patients who will really benefit from these procedures. Moreover, imaging enhances the understanding of the underlying mechanisms of atrial remodeling and might assists in refining the risk of stroke, which help to select the best medical therapies/interventions. In summary, evaluation of LA enlargement, LA remodeling and fibrosis with imaging techniques adds clinical and prognostic information and should be assessed as a part of routine comprehensive AF evaluation.

Echocardiographic evaluation of the right atrial size and function: Relevance for clinical practice

Right atrial (RA) structural and functional evaluations have recently emerged as powerful biomarkers for adverse events in various cardiovascular conditions. Quantitative analysis of the right atrium, usually performed with volume changes or speckle-tracking echocardiography (STE), has markedly changed our understanding of RA function and remodeling. Knowledge of reference echocardiographic values and measurement methods of RA volumes and myocardial function is a prerequisite to introduce RA quantitation in the clinical routine. This review describes the methodology, benefits and pitfalls of measuring RA size and function by echocardiography based on the current understanding of right atrial anatomy and physiological function and provides the current knowledge of right atrial function in related cardiac diseases.

Cardiac geometry, function and mechanics in left ventricular non-compaction cardiomyopathy with preserved ejection fraction

BACKGROUND

Left ventricular non-compaction (LVNC) cardiomyopathy in adults has primarily been studied with a phenotypic expression of low ejection fraction (EF) and dilated cardiomyopathy; however, data on LVNC with preserved EF is scarce. The present study aimed to evaluate cardiac geometry and mechanics in LVNC patients with preserved EF.

METHODS

A retrospective cohort study of patients diagnosed with LVNC and a preserved EF between 2008 and 2019 was performed. LVNC was defined according to the presence of established transthoracic 2D echocardiographic (TTE) criteria as follows: (1) prominent LV trabeculations with deep recesses; (2) bi-layered myocardial appearance; and, (3) systolic non-compacted:compacted ratio≥ 2. Subjects were matched 1:1 to controls without LVNC referred for routine TTE. Geometric, functional and mechanics parameters were analyzed in the two cohorts using 2D and speckle-tracking TTE.

RESULTS

Seventeen patients with LVNC and preserved EF were identified. Compared with controls, patients with LVNC had similar LV systolic function and chamber dimensions, but a larger mass and relative wall thickness, and more abnormal LV geometry (76% vs. 18%, p = 0.002), LA remodeling, and pulmonary hypertension. Global longitudinal strain was significantly decreased (-15.4 ± 3.2 vs. -18.9 ± 2.8%, p =  < 0.01) and the prevalence of rigid body rotation was significantly increased (57% vs. 14%, p = 0.05) in the LVNC population. The peak twist values were comparable in both cohorts.

CONCLUSIONS

Impaired LV geometry and longitudinal mechanics, as well as increased myocardial stiffness as expressed by rigid body rotation, characterize LVNC with preserved EF when compared with controls.

Left Ventricular Twist Mechanics Before and After Aortic Valve Replacement: A Feasibility Study and Exploratory Analysis

Introduction. We examined whether intraoperative assessment of left ventricular (LV) twist mechanics is feasible with transesophageal echocardiography (TEE). We then explored whether twist mechanics were altered by hemodynamic conditions or patient comorbidities. Methods. In this sub-analysis of clinical trial data, transgastric short-axis echocardiographic images of the LV base and apex were collected in patients having aortic valve replacement (AVR) at baseline and end of surgery. Transvalvular gradients and LV systolic and diastolic function were assessed using two-dimensional (2D) and Doppler echocardiography. 2D speckle-tracking echocardiography was used for off-line analysis of LV twist, twisting rate, and untwisting rate. We examined the intraoperative change in twist mechanics before and after AVR. LV twist mechanics were also explored by diabetic status, need for coronary artery bypass grafting (CABG), and use of epinephrine/norepinephrine. Results. Of 40 patients, 16 patients had acceptable TEE images for off-line LV twist analysis. Baseline median [Q1, Q3] LV twist was 12 [7, 16]°, twisting rate was 72 [41, 97]°/sec, and untwisting rate was -91 [-154, -56]°/s. Median [Q1, Q3] change in LV twist at end of surgery was -2 [-5, 3]°, twisting rate was 7 [-33, 31]°/s, and untwisting rate was 0 [-11, 43]°/s. No difference was noted between diabetic and non-diabetic patients or AVR and AVR-CABG patients. Conclusion. LV twist was augmented in patients with aortic stenosis, though twist indices were not affected by reduced afterload, diabetes, or coronary artery disease. Intraoperative assessment of twist mechanics may provide unique information on LV systolic and diastolic function, though fewer than 50% of TEE examinations successfully assessed twist. Clinical Trial Registry. This work is a sub-analysis of a clinical trial, registered on ClinicalTrials.gov on August 19, 2010 (NCT01187329), Andra Duncan, Principal Investigator.

Right Ventricular Longitudinal Strain in Patients with Heart Failure

Patients with heart failure (HF) have high morbidity and mortality. Accurate assessment of right ventricular (RV) function has important prognostic significance in patients with HF. However, conventional echocardiographic parameters of RV function have limitations in RV assessments due to the complex geometry of right ventricle. In recent years, speckle tracking echocardiography (STE) has been developed as promising imaging technique to accurately evaluate RV function. RV longitudinal strain (RVLS) using STE, as a sensitive index for RV function evaluation, displays the powerfully prognostic value in patients with HF. Therefore, the aim of the present review was to summarize the utility of RVLS in patients with HF.

Acute regional changes in myocardial strain may predict ventricular remodelling after myocardial infarction in a large animal model

To identify predictors of left ventricular remodelling (LVR) post-myocardial infarction (MI) and related molecular signatures, a porcine model of closed-chest balloon MI was used along with serial cardiac magnetic resonance imaging (CMRI) up to 5-6 weeks post-MI. Changes in myocardial strain and strain rates were derived from CMRI data. Tissue proteomics was compared between infarcted and non-infarcted territories. Peak values of left ventricular (LV) apical circumferential strain (ACS) changed over time together with peak global circumferential strain (GCS) while peak GLS epicardial strains or strain rates did not change over time. Early LVR post-MI enhanced abundance of 39 proteins in infarcted LV territories, 21 of which correlated with LV equatorial circumferential strain rate. The strongest associations were observed for D-3-phosphoglycerate dehydrogenase (D-3PGDH), cysteine and glycine-rich protein-2, and secreted frizzled-related protein 1 (sFRP1). This study shows that early changes in regional peak ACS persist at 5-6 weeks post-MI, when early LVR is observed along with increased tissue levels of D-3PGDH and sFRP1. More studies are needed to ascertain if the observed increase in tissue levels of D-3PGDH and sFRP1 might be casually involved in the pathogenesis of adverse LV remodelling.

The impact of lower body compression garment on left ventricular rotational mechanics in patients with lipedema-Insights from the three-dimensional speckle tracking echocardiographic MAGYAR-Path Study

Lipedema is a lymphedema-masquerading symmetrical, bilateral and disproportional obesity. Its conservative maintenance treatment comprises the use of flat-knitted compression pantyhoses. Lipedema is known to be associated with left ventricular morphological and functional alterations. The present study aimed to assess the effects of graduated compression stockings on left ventricular (LV) rotational mechanics measured by three-dimensional speckle-tracking echocardiography (3DSTE) in lipedema patients. The present study comprised twenty lipedema patients (mean age: 45.8 ± 11.0 years, all females) undergoing 3DSTE who were also compared to 51 age- and gender-matched healthy controls (mean age: 39.8 ± 14.1 years, all females). 3DSTE analysis was performed at rest, and subsequent to 1 hour application of compression class 2 made-to-measure flat-knitted pantyhose. Six lipedema patients showed significant LV rotational abnormalities. Of the remaining fourteen lipedema patients LV basal rotation rotation showed significant reduction, while LV apical rotation showed significant increase with unchanged LV twist after a 60-minute use of compression garment. Significant changes in LV rotational mechanics could be detected among 14 women with lipedema after the use of compression garment however six probands have special LV rotational abnormalities at baseline and/or after compression.

Retinoid X receptor agonists attenuates cardiomyopathy in streptozotocin-induced type 1 diabetes through LKB1-dependent anti-fibrosis effects

Diabetic cardiac fibrosis increases ventricular stiffness and facilitates the occurrence of diastolic dysfunction. Retinoid X receptor (RXR) plays an important role in cardiac development and has been implicated in cardiovascular diseases. In the present study, we investigated the effects of RXR agonist treatment on streptozotocin (STZ)-induced diabetic cardiomyopathy (DCM) and the underlying mechanism. Sprague-Dawley (SD) rats induced by STZ injection were treated with either RXR agonist bexarotene (Bex) or vehicle alone. Echocardiography was performed to determine cardiac structure and function. Cardiac fibroblasts (CFs) were treated with high glucose (HG) with or without the indicated concentration of Bex or the RXR ligand 9-cis-retinoic acid (9-cis-RA). The protein abundance levels were measured along with collagen, body weight (BW), blood biochemical indexes and transforming growth factor-β (TGF-β) levels. The effects of RXRα down-regulation by RXRα small interfering RNA (siRNA) were examined. The results showed that bexarotene treatment resulted in amelioration of left ventricular dysfunction by inhibiting cardiomyocyte apoptosis and myocardial fibrosis. Immunoblot with heart tissue homogenates from diabetic rats revealed that bexarotene activated liver kinase B1 (LKB1) signaling and inhibited p70 ribosomal protein S6 kinase (p70S6K). The increased collagen levels in the heart tissues of DCM rats were reduced by bexarotene treatment. Treatment of CFs with HG resulted in significantly reduced LKB1 activity and increased p70S6K activity. RXRα mediated the antagonism of 9-cis-RA on HG-induced LKB1/p70S6K activation changes in vitro. Our findings suggest that RXR agonist ameliorates STZ-induced DCM by inhibiting myocardial fibrosis via modulation of the LKB1/p70S6K signaling pathway. RXR agonists may serve as novel therapeutic agents for the treatment of DCM.

The influence of sex on left ventricular remodeling in arterial hypertension

Hypertension represents one of the most important and most frequent cardiovascular risk factors responsible for heart failure (HF) development. Both sexes are equally affected by arterial hypertension. The difference is lying in the fact that prevalence of hypertension as well as hypertension-induced target organ damage varies during lifetime due to substantial variation of sex hormones in women. Left ventricular (LV) structural, functional, and mechanical changes induced by hypertension are well-known complications that occur in both sexes and they are responsible for HF development. However, their prevalence is significantly different between women and men, which could potentially explain the variation in HF occurrence and prognosis between the sexes. Studies have shown that the prevalence of left ventricular hypertrophy is higher in men. The data are not consistent regarding LV diastolic dysfunction and a similar report has been given for LV mechanical changes. Most investigations agree that LV longitudinal strain is lower among hypertensive men. However, even in the healthy population, men have lower LV longitudinal strain and the cutoff values are still missing. Therefore, it would be difficult to draw the conclusion that LV mechanical dysfunction is more prevalent among men. The main mechanisms responsible for sex-related LV remodeling are sex hormones and their influence on biohumoral systems. This review provides an updated overview of the available data about sex-related LV remodeling, as well as potential mechanisms for these changes, in the patients with arterial hypertension.

Speckle-tracking echocardiography combined with imaging mass spectrometry assesses region-dependent alterations

Left ventricular (LV) contraction is characterized by shortening and thickening of longitudinal and circumferential fibres. To date, it is poorly understood how LV deformation is altered in the pathogenesis of streptozotocin (STZ)-induced type 1 diabetes mellitus-associated diabetic cardiomyopathy and how this is associated with changes in cardiac structural composition. To gain further insights in these LV alterations, eight-week-old C57BL6/j mice were intraperitoneally injected with 50 mg/kg body weight STZ during 5 consecutive days. Six, 9, and 12 weeks (w) post injections, echocardiographic analysis was performed using a Vevo 3100 device coupled to a 30-MHz linear-frequency transducer. Speckle-tracking echocardiography (STE) demonstrated impaired global longitudinal peak strain (GLS) in STZ versus control mice at all time points. 9w STZ animals displayed an impaired global circumferential peak strain (GCS) versus 6w and 12w STZ mice. They further exhibited decreased myocardial deformation behaviour of the anterior and posterior base versus controls, which was paralleled with an elevated collagen I/III protein ratio. Additionally, hypothesis-free proteome analysis by imaging mass spectrometry (IMS) identified regional- and time-dependent changes of proteins affecting sarcomere mechanics between STZ and control mice. In conclusion, STZ-induced diabetic cardiomyopathy changes global cardiac deformation associated with alterations in cardiac sarcomere proteins.

Obstructive sleep apnea and cardiac mechanics: how strain could help us?

Obstructive sleep apnea (OSA) syndrome is the most common sleep-breathing disorder, which is associated with increase cardiovascular morbidity and mortality. OSA increases risk of resistant arterial hypertension, coronary artery disease, heart failure, pulmonary hypertension, and stroke. Studies showed the significant relationship between OSA and cardiac remodeling. The majority of investigations were focused on the left ventricle and its hypertrophy and function. Fewer studies investigated right ventricular structure and function revealing deteriorated diastolic and systolic function. Data regarding left and right ventricular mechanics in OSA patients are scarce and controversial. The results of the studies that were focused on the influence of continuous positive airway pressure and weight reduction on cardiac remodeling revealed favorable effect on left and right ventricular structure and function. Recently published analyses confirmed positive effect of treatment on cardiac mechanics. Deterioration of left and right ventricular mechanics occurs before functional and structural cardiac impairments in the cascade of cardiac remodeling and therefore the assessment of left and right ventricular strain may represent a cornerstone in detection of subtle cardiac changes that develop significantly before other, often irreversible, alterations. Considering the fact that left and right ventricular strains have important predictive value in wide range of cardiovascular diseases, one should consider the evaluation of left and right ventricular strains in the routine echocardiographic assessment at all stages of disease-from diagnosis, during follow-up and evaluation of therapeutic effects. The main aim of this review is to provide the current overview of cardiac mechanics in OSA patients before and after (during) therapy, as well as mechanisms that could be responsible for cardiac changes.

Use of speckle tracking to assess heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) currently represents approximately 50% of heart failure (HF) cases in the USA and is increasingly recognized as a leading cause of morbidity and mortality. Recent data suggest that the prevalence of HFpEF relative to HF with reduced ejection fraction (HFrEF) is increasing at a rate of 1% per year. With an aging population and increasing risk factors such as hypertension, obesity, and diabetes mellitus, HFpEF will soon be the most prevalent HF phenotype. Two-dimensional speckle-tracking echocardiography (STE) has been used to diagnose HFpEF specifically by focusing on the longitudinal systolic function of the left ventricle (LV). Yet there are many patients with HFpEF in whom there are no differences in LV global longitudinal systolic strain, but there are changes in left atrial function and structure. There are several proposed pathophysiological mechanisms for HFpEF such as endothelial dysfunction, interactions among proteins, signaling pathways, and myocardial bioenergetics. Yet only one specific therapy, mineralocorticoid receptor antagonist, spironolactone, is recommended as a treatment for patients with HFpEF. However, spironolactone does not address many of the pathophysiologic changes that occur in HFpEF, thus new novel therapeutic agents are needed. With the limited available therapies, clinicians should use STE to assess for the presence of this syndrome in their patients to provide effective diagnosis and management.

Sex-related Left Ventricle Rotational and Torsional Mechanics by Block Matching Algorithm

Background:

The aim of the present study was to evaluate how left ventricular twist and torsion are associated with sex between sex groups of the same age.

Materials and Methods:

In this analytical study, twenty one healthy subjects were scanned in left ventricle basal and apical short axis views to run the block matching algorithm; instantaneous changes in the base and apex rotation angels were estimated by this algorithm and then instantaneous changes of the twist and torsion were calculated over the cardiac cycle.

Results:

The rotation amount between the consecutive frames in basal and apical levels was extracted from short axis views by tracking the speckle pattern of images. The maximum basal rotation angle for men and women were -6.94°±1.84 and 9.85°±2.36 degrees (p-value = 0.054), respectively. Apex maximum rotation for men was -8.89°±2.04 and for women was 12.18°±2.33 (p-value < 0.05). The peak of twist angle for men and women was 16.78 ± 1.83 and 20.95± 2.09 degrees (p-value < 0.05), respectively. In men and women groups, the peak of calculated torsion angle was 5.49°±1.04 and 7.12± 1.38 degrees (p-value < 0.05), respectively.

Conclusion:

The conclusion is that although torsion is an efficient parameter for left ventricle function assessment, because it can take in account the heart diameter and length, statistic evaluation of the results shows that among men and women LV mechanical parameters are significantly different. This study was mainly ascribed to the dependency of the torsion and twist on patient sex.

Strain Analysis of Left Ventricular Function in the Association of Hypertrophic Cardiomyopathy and Systemic Arterial Hypertension

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is the most common heart disease of genetic origin in the world population, with a prevalence of at least 1/500. The association with systemic arterial hypertension (SAH) is not uncommon, as it affects approximately 25% of the world population. Most studies aim at the differential diagnosis between these diseases, but little is known about the magnitude of this association.

OBJECTIVE

To compare left ventricular global longitudinal strain (GLS) in HCM patients with and without associated SAH.

METHODS

Retrospective cross-sectional study that included 45 patients with HCM and preserved ejection fraction, with diagnosis confirmed by magnetic resonance imaging, including 14 hypertensive patients. Transthoracic echocardiography was performed, with emphasis on left ventricular myocardial strain analysis using GLS. In this study, p < 0.05 was considered statistically significant.

RESULTS

Left ventricular strain was significantly lower in hypertensive individuals compared to normotensive individuals (-10.29 ± 2.46 vs. -12.35% ± 3.55%, p = 0.0303), indicating greater impairment of ventricular function in that group. Mean age was also significantly higher in hypertensive patients (56.1 ± 13.9 vs. 40.2 ± 12.7 years, p = 0.0001). Diastolic dysfunction was better characterized in hypertensive patients (p = 0.0242).

CONCLUSION

Myocardial strain was significantly lower in the group of patients with HCM and SAH, suggesting greater impairment of ventricular function. This finding may be related to a worse prognosis with early evolution to heart failure. Prospective studies are required to confirm this hypothesis.

An introduction to left ventricular strain

PURPOSE OF REVIEW

The assessment of left ventricular function by two-dimensional (2D) transthoracic echocardiography (TTE) is conventionally performed by measuring the ejection fraction, which has been shown to have important prognostic implications. However, left ventricular ejection fraction (LVEF) has notable shortcomings, including limited reproducibility, suboptimal inter/intraobserver variability and dependence on load/volume. Furthermore, subclinical left ventricular dysfunction cannot be measured with LVEF. With the advent of left ventricular deformation (strain) analysis, a new and robust means for assessing left ventricular function has emerged.

RECENT FINDINGS

Contemporary research and guidelines have attempted to standardize the definition, acquisition and measurement of left ventricular strain. In addition, multiple studies have sought to establish normal values for left ventricular strain in addition to evaluating the benefits and prognostic value of strain assessment.

SUMMARY

This article reviews the definition of left ventricular strain, outlines the types of strain and reviews how strain is acquired and measured. In addition, the advantages of strain analysis over LVEF as well as the incremental prognostic value of strain are examined. We further review the challenges associated with strain imaging as well as outline the future of strain imaging.

Speckle tracking echocardiography in the critically ill: enticing research with minimal clinical practicality or the answer to non-invasive cardiac assessment?

Echocardiography is developing rapidly. Speckle tracking echocardiography is the latest semi-automatic tool that has potential to quantitatively describe cardiac dysfunction that may be unrecognised by conventional echocardiography. It is a non-Doppler, angle-independent, feasible and reproducible method to evaluate myocardial function in both non-critically ill and critically ill populations. Increasingly it has become a standard measure of both left and right ventricle function in specific patient groups, e.g. chemotherapy-induced cardiomyopathy or pulmonary hypertension. To date there are few studies in the critically ill, predominantly in sepsis, yet all describe dysfunction beyond standard measures. Other areas of interest include heart-lung interactions, right ventricle function and twist and torsion of the heart. A word of caution is required, however, in that speckle tracking echocardiography is far from perfect and is more challenging, particularly in the critically ill, than implied by many published studies. It takes time to learn and perform and most values are not validated, particularly in the critically ill. We should be cautious in accepting that the latest software used in cardiology cohorts will automatically be the answer in the critically ill. Even with these limitations the technology is enticing and results fascinating. We are uncovering previously undescribed dysfunction and although it currently is essentially a research-based activity, there is great promise as a clinical tool as echocardiography analysis becomes more automated, and potentially speckle tracking echocardiography could help describe cardiac function in critical illness more accurately than is possible with current techniques.

Cardiac Imaging in Heart Failure with Comorbidities

Imaging modalities stand at the frontiers for progress in congestive heart failure (CHF) screening, risk stratification and monitoring. Advancements in echocardiography (ECHO) and Magnetic Resonance Imaging (MRI) have allowed for improved tissue characterizations, cardiac motion analysis, and cardiac performance analysis under stress. Common cardiac comorbidities such as hypertension, metabolic syndromes and chronic renal failure contribute to cardiac remodeling, sharing similar pathophysiological mechanisms starting with interstitial changes, structural changes and finally clinical CHF. These imaging techniques can potentially detect changes earlier. Such information could have clinical benefits for screening, planning preventive therapies and risk stratifying patients. Imaging reports have often focused on traditional measures without factoring these novel parameters. This review is aimed at providing a synopsis on how we can use this information to assess and monitor improvements for CHF with comorbidities.

Transthoracic Speckle Tracking Echocardiography for the Quantitative Assessment of Left Ventricular Myocardial Deformation

The value of conventional echocardiography is limited by differences in inter-individual image interpretation and therefore largely dependent on the examiners' expertise. Speckle tracking Echocardiography (STE) is a promising but technically challenging method that can be used to quantitatively assess regional and global systolic and diastolic myocardial performance. Myocardial strain and strain rate can be measured in all three dimensions - radial, circumferential, longitudinal - of myocardial deformation. Standard cross-sectional two-dimensional B-mode images are recorded and subsequently postprocessed by automated continuous frame-by-frame tracking and motion analysis of speckles within the myocardium. Images are recorded as digital loops and synchronized to a 3-lead EKG for timing purposes. Longitudinal deformation is assessed in the apical 4-, 3-, and 2-chamber views. Circumferential and radial deformation are measured in the parasternal short axis plane. Optimal image quality and accurate tissue tracking are paramount for the correct determination of myocardial performance parameters. Utilizing transthoracic STE in a healthy volunteer, the present article is a detailed outline of the essential steps and potential pitfalls of quantitative echocardiographic myocardial deformation analysis.

Anatomical Image Registration Using Volume Conservation to Assess Cardiac Deformation From 3D Ultrasound Recordings

Myocardial deformation imaging can provide valuable insights in myocardial mechanics and help in the diagnosis, prognosis and follow-up of cardiac diseases. However, extracting these indices in 3D is challenging due to the limitations in spatial and temporal resolution of the current volumetric ultrasound systems. For this purpose, we developed an anatomical free-form deformation image registration framework which is locally adapted to the anatomy of the heart. In this work we explored whether incorporating a myocardial volume conservation regularizer would improve strain estimates. We evaluated our technique on in silico echo sequences featuring realistic speckle textures and showed the volume conservation regularizer to be beneficial in reducing strain errors further when used in combination with a smoothness penalty. This combination led to more physiological boundary conditions. It also made distinguishing ischemic from normal segments easier in clinical images.