The impact of preload on 3-dimensional deformation parameters: principal strain, twist and torsion

Hyperacute Effects of Mitral Transcatheter Edge-to-Edge Repair on Left Ventricular Volumes and Functions

Transcatheter edge-to-edge repair (TEER) is an effective intervention for high-risk patients with severe symptomatic mitral regurgitation (MR); however, its acute impact on left ventricular (LV) function has not been well-studied using advanced echocardiographic techniques. This study investigated the immediate effects of TEER on LV volumes and functions and their influence on midterm outcomes, using high-resolution 3-dimensional transesophageal echocardiography. In 80 patients who underwent TEER for severe MR (mean age 79 ± 8 years, 49% with primary MR), LV end-diastolic volume and stroke volume significantly decreased (161 ± 61 to 147 ± 54 ml and 69 ± 18 to 50 ± 15 ml, respectively), whereas end-systolic volume increased (92 ± 60 to 97 ± 45 ml, p <0.0001 for all). Left ventricular ejection fraction (LVEF) (48 ± 16% to 38 ± 14%), global longitudinal strain (16.2 ± 6.8% to 12.8 ± 5.4%), and global circumferential strain (25 ± 10.5% to 18.7 ± 8.5%) deteriorated significantly (p <0.0001 for all). Absolute reductions in LVEF and global circumferential strain were associated with baseline values and afterload reduction, indicated by 3-dimensional vena contracta area decrease (r = 0.47 and r = 0.65, p <0.0001), whereas global longitudinal strain reduction was linked to baseline values and inversely proportional to LV end-diastolic volume (r = 0.63, p <0.0001). Relative LVEF reduction emerged as the strongest predictor of mortality, with a hazard ratio of 1.76 (1.12 to 2.76) per 10% decrease. In conclusion, the acute decrease in LV function after TEER correlates with the degree of MR reduction, with greater impacts observed in circumferential function and patients with higher baseline LVEF. Relative LVEF reduction is a critical echocardiographic predictor of mortality.

Global longitudinal strain as an early marker of cardiac damage after cardiotoxic medications, a state of the art review

Ejection fraction (EF) is the principal parameter used clinically to assess cardiac function and provides prognostic information. However, significant myocardial damage can be present despite preserved EF. Recently, the measurement of left ventricle (LV) deformation by global longitudinal strain (GLS) has been introduced as a novel early marker of cardiac dysfunction. Cardiotoxicity is a frequent side effect of several drugs most notably those used in the treatment of cancer. Although oncology drugs remain the best known cardiotoxic medications, many other drugs can potentially affect LV function. The early recognition of LV dysfunction due to cardiotoxicity is important and of increasing clinical relevance particularly with the rapid pace of development of new drugs. The aim of our review is to provide an overview of the current literature regarding utility of GLS to assess drug-induced myocardial damage. We propose that GLS is a sensitive early marker of myocardial dysfunction associated with the use of certain medications with high risk of cardiotoxicity. Thus, the use of this technique can potentially alert the clinician to myocardial toxicity before reductions in EF are seen.

Downregulation of RIP3 ameliorates the left ventricular mechanics and function after myocardial infarction via modulating NF-κB/NLRP3 pathway

Adverse cardiac mechanical remodeling is critical for the progression of heart failure following myocardial infarction (MI). We previously demonstrated the involvement of RIP3-mediated necroptosis in the loss of functional cardiomyocytes and cardiac dysfunction post-MI. Herein, we investigated the role of RIP3 in NOD-like receptor protein 3 (NLRP3)-mediated inflammation and evaluated the effects of RIP3 knockdown on myocardial mechanics and functional changes after MI. Our findings revealed that mice with MI for 4 weeks exhibited impaired left ventricular (LV) myocardial mechanics, as evidenced by a significant decrease in strain and strain rate in each segment of the LV wall during both systole and diastole. However, RIP3 knockdown ameliorated cardiac dysfunction by improving LV myocardial mechanics not only in the anterior wall but also in other remote nonischemic segments of the LV wall. Mechanistically, knockdown of RIP3 effectively inhibited the activation of the nuclear factor kappa-B (NF-κB)/NLRP3 pathway, reduced the levels of interleukin-1β (IL-1β) and interleukin-18 (IL-18) in the heart tissues, and mitigated adverse cardiac remodeling following MI. These results suggest that downregulation of RIP3 holds promise for preventing myocardial inflammation and cardiac mechanical remodeling following MI by regulating the NF-κB/NLRP3 pathway.

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.

Cardioprotective Effect of Acute Intradialytic Exercise: A Comprehensive Speckle-Tracking Echocardiography Analysis

SIGNIFICANCE STATEMENT

Hemodialysis (HD) can lead to acute left ventricular (LV) myocardial wall motion abnormalities (myocardial stunning) due to segmental hypoperfusion. Exercise during dialysis is associated with favorable effects on central hemodynamics and BP stability, factors considered in the etiology of HD-induced myocardial stunning. In a speckle-tracking echocardiography analysis, the authors explored effects of acute intradialytic exercise (IDE) on LV regional myocardial function in 60 patients undergoing HD. They found beneficial effects of IDE on LV longitudinal and circumferential function and on torsional mechanics, not accounted for by cardiac loading conditions or central hemodynamics. These findings support the implementation of IDE in people with ESKD, given that LV transient dysfunction imposed by repetitive HD may contribute to heart failure and increased risk of cardiac events in such patients.

BACKGROUND

Hemodialysis (HD) induces left ventricular (LV) transient myocardial dysfunction. A complex interplay between linear deformations and torsional mechanics underlies LV myocardial performance. Although intradialytic exercise (IDE) induces favorable effects on central hemodynamics, its effect on myocardial mechanics has never been comprehensively documented.

METHODS

To evaluate the effects of IDE on LV myocardial mechanics, assessed by speckle-tracking echocardiography, we conducted a prospective, open-label, two-center randomized crossover trial. We enrolled 60 individuals with ESKD receiving HD, who were assigned to participate in two sessions performed in a randomized order: standard HD and HD incorporating 30 minutes of aerobic exercise (HDEX). We measured global longitudinal strain (GLS) at baseline (T0), 90 minutes after HD onset (T1), and 30 minutes before ending HD (T2). At T0 and T2, we also measured circumferential strain and twist, calculated as the net difference between apical and basal rotations. Central hemodynamic data (BP, cardiac output) also were collected.

RESULTS

The decline in GLS observed during the HD procedure was attenuated in the HDEX sessions (estimated difference, -1.16%; 95% confidence interval [95% CI], -0.31 to -2.02; P = 0.008). Compared with HD, HDEX also demonstrated greater improvements from T0 to T2 in twist, an important component of LV myocardial function (estimated difference, 2.48°; 95% CI, 0.30 to 4.65; P = 0.02). Differences in changes from T0 to T2 for cardiac loading and intradialytic hemodynamics did not account for the beneficial effects of IDE on LV myocardial mechanics kinetics.

CONCLUSIONS

IDE applied acutely during HD improves regional myocardial mechanics and might warrant consideration in the therapeutic approach for patients on HD.

Cardiac mechanostructure: Using mechanics and anisotropy as inspiration for developing epicardial therapies in treating myocardial infarction

The mechanical environment and anisotropic structure of the heart modulate cardiac function at the cellular, tissue and organ levels. During myocardial infarction (MI) and subsequent healing, however, this landscape changes significantly. In order to engineer cardiac biomaterials with the appropriate properties to enhance function after MI, the changes in the myocardium induced by MI must be clearly identified. In this review, we focus on the mechanical and structural properties of the healthy and infarcted myocardium in order to gain insight about the environment in which biomaterial-based cardiac therapies are expected to perform and the functional deficiencies caused by MI that the therapy must address. From this understanding, we discuss epicardial therapies for MI inspired by the mechanics and anisotropy of the heart focusing on passive devices, which feature a biomaterials approach, and active devices, which feature robotic and cellular components. Through this review, a detailed analysis is provided in order to inspire further development and translation of epicardial therapies for MI.

Changes in left ventricular and atrial mechanics and function after dialysis in patients with end-stage renal disease

Background

Hemodialysis (HD) can influence end-stage renal disease (ESRD) patients' circulatory system. The present study aimed to evaluate the effect of volume depletion on left ventricular (LV) and left atrial (LA) function and determine the volume-independent parameters before and after HD in patients with ESRD.

Methods

Between January 2018 and January 2019, we recruited long-term HD patients (n=40, 51.0±16.4 years), excluding those with structural cardiac disease. Echocardiographic parameters, including LV and LA volumes, flow Doppler, pulsed tissue Doppler, and speckle tracking echocardiography (STE) before and after HD (within 24 h), were examined, and the values were compared.

Results

Following HD, alteration in LV end-systolic volume was not detected, whereas LV end-diastolic volume (90.18±23.91 vs. 84.21±23.54 mL, P=0.036) and LV ejection fraction (LVEF; 64.63%±6.56% vs. 62.84%±6.56%, P=0.049) decreased. Peak early diastolic trans-mitral flow velocity (E-wave; 82.22±20.13 vs. 72.43±18.32 cm/s, P<0.001), peak early diastolic tissue Doppler velocity (e'; 6.45±1.88 vs. 5.77±1.63 cm/s, P<0.001) at the septal side of the mitral annulus, the ratio of early to late Doppler velocities of diastolic mitral inflow (0.90±0.27 vs. 0.79±0.23, P<0.001), and the average E/e' ratio (12.54±4.08 vs. 11.28±4.52, P=0.049) decreased significantly. No significant difference was found in peak blood flow velocity at the mitral valve during late diastole and e' at the lateral side of the mitral annulus after HD. LA volume index (35.55±12.61 vs. 30.22±9.80 mL/m², P<0.001), tricuspid regurgitation velocity (260.11±36.54 vs. 242.37±32.22 cm/s, P=0.002), and pulmonary artery systolic pressure (33.63±11.29 vs. 29.94±7.80 mmHg, P=0.006) significantly decreased. LV global longitudinal systolic strain (GLS) of 4-chamber view (-24.37%±3.02% vs. -23.38%±3.33%, P=0.019), rather than global circumferential systolic strain, exhibited significant change after HD. Significant changes were also found in LV longitudinal early diastolic strain rate (LSRe; 1.17±0.25 vs. 1.05±0.24 s^-1, P<0.001) and early diastolic global radial velocity (Ve; 2.62±0.59 vs. 2.25±0.67 cm/s, P=0.011) after HD, but not in other strain rates and global radial velocity measurements. LA maximal volume (35.55±12.61 vs. 30.22±9.80 mL/m², P<0.001), LA total emptying fraction (54.19%±10.39% vs. 49.63%±11.05%, P=0.009), and LA passive emptying fraction (32.23%±12.86% vs. 26.81%±9.28%, P=0.004) decreased significantly after HD, while LA minimal volume, the volume at the onset of atrial systole, and LA active emptying fraction after HD were not significantly different.

Conclusions

Most indices of systolic (LVEF and GLS of 4-chamber view) and early diastolic function (E-wave, e', LSRe, global radial Ve, and LA passive emptying fraction) were preload dependent. Late diastolic indices, including LV late diastolic global longitudinal strain rate, late diastolic global radial velocity, and LA active emptying fraction, did not change with volume depletion.

A review of current trends in three-dimensional analysis of left ventricular myocardial strain

Three-dimensional (3D) left ventricular (LV) myocardial strain measurements using transthoracic 3D echocardiography speckle tracking analysis have several advantages over two-dimensional (2D) LV strain measurements, because 3D strain values are derived from the entire LV myocardium, yielding more accurate estimates of global and regional LV function. In this review article, we summarize the current status of 3D LV myocardial strain. Specifically, we describe how 3D LV strain analysis is performed. Next, we compare characteristics of 2D and 3D strain, and we explain validation of 3D strain measurements, feasibility and measurement differences between 2D and 3D strain, reference values of 3D strain, and its applications in several clinical scenarios. In some parts of this review, we used a meta-analysis to draw reliable conclusions. We also describe the added value of 3D over 2D strain in several specific pathologies and prognoses. Finally, we discuss novel techniques using 3D strain and suggest its future directions.

Acute stunning effect of hemodialysis on myocardial performance: A three-dimensional speckle tracking echocardiographic study

The effects of acute changes during hemodialysis (HD) on the myocardium are not yet known. The invention of three-dimensional speckle tracking echocardiography (3DSTE) has offered clinicians a new method to assess the movements of ventricular segments simultaneously in three spatial directions. The aim of this study was to evaluate the effect of first weekly standard HD process on the left ventricle (LV) and right ventricle (RV) global and regional myocardial function in patients with normal left ventricle ejection fraction using 3DSTE-derived indices. Patients (n=38) receiving maintenance HD in our clinic who have no known cardiovascular disease are examined just before and after a HD session using 3DSTE. Demographic and comorbidity data, renal replacement treatment characteristics, and laboratory test results are recorded. 3DSTE analysis is performed to calculate the LV global longitudinal, circumferential area and radial peak systolic strain, as well as RV septum and free-wall longitudinal strain and fractional area change. Patients are aged 52.8 ± 13.6 years and 52.6% of them are male. Mean dialysis duration is 56 months. The LV strain values of the patients changed markedly before and after HD (GLS: -14.2 ± 5.2, -11.1 ± 4.6 [P < .001], GCS: -14.8 ± 4.2, -12.4 ± 5.28 [P < .009]; GRS: 41.5 ± 16, 33.3 ± 16.5 [P = .003]; AREA -24.7 ± 7.2, -20.1 ± 7.6 [P = .001], respectively). We could not demonstrate any improvement in RV strain values before or after HD. LV strain values are positively correlated with blood pressure variability during the dialysis sessions. LV function is preserved better after HD in patients on beta or calcium channel blocker therapy compared to those who do not use these agents (P < .001, P < .01, respectively). HD treatment results in deterioration in all LV strain directions but not in RV. Strain assessment may improve vascular risk stratification of patients on chronic HD.

Three-dimensional myocardial strain correlates with murine left ventricular remodelling severity post-infarction

Heart failure continues to be a common and deadly sequela of myocardial infarction (MI). Despite strong evidence suggesting the importance of myocardial mechanics in cardiac remodelling, many MI studies still rely on two-dimensional analyses to estimate global left ventricular (LV) function. Here, we integrated four-dimensional ultrasound with three-dimensional strain mapping to longitudinally characterize LV mechanics within and around infarcts in order to study the post-MI remodelling process. To induce infarcts with varying severities, we separated 15 mice into three equal-sized groups: (i) sham, (ii) 30 min ischaemia-reperfusion, and (iii) permanent ligation of the left coronary artery. Four-dimensional ultrasound from a high-frequency small animal system was used to monitor changes in LV geometry, function and strain over 28 days. We reconstructed three-dimensional myocardial strain maps and showed that strain profiles at the infarct border followed a sigmoidal behaviour. We also identified that mice with mild remodelling had significantly higher strains in the infarcted myocardium than those with severe injury. Finally, we developed a new approach to non-invasively estimate infarct size from strain maps, which correlated well with histological results. Taken together, the presented work provides a thorough approach to quantify regional strain, an important component when assessing post-MI remodelling.

The value of left ventricular strain-volume loops in predicting response to cardiac resynchronization therapy

BACKGROUND

Three-dimensional (3D) speckle tracking imaging (STI) allows the simultaneous assessment of left ventricular (LV) strain and volume. We aim to explore the value of LV strain-volume loops in predicting response to cardiac resynchronization therapy (CRT).

METHODS

Forty heart failure (HF) patients scheduled for CRT and twenty healthy individuals were enrolled. All subjects received a 3D echocardiography and 3D STI analysis to acquire LV global and segmental principal strain (PS) and volume simultaneously. Values were plotted in a Cartesian system to construct PS-volume loop which was assessed using the two characteristics of the linear fitting curve: the slope and the coefficient of determination (R²-S/D coupling).

RESULTS

HF patients at baseline showed significantly lower slope and R²-S/D coupling of all PS-volume loops than healthy subjects. As for as comparing Segmental PS-Global volume loop at baseline, Midseptal R²-S/D coupling was lower and Midlateral slope was higher in CRT responders than in non-responders. For each individual, the abnormal segmental heterogeneity of Midseptal slope and R²-S/D coupling were lower than Midlateral was observed only in responders. At follow-up, significant improvements of the Midseptal slope and R²-S/D coupling were observed in responders. Midseptal R²-S/D coupling at baseline was an independent predictor of CRT response and the cut-off value of 0.55 was recommended with sensitivity of 89% and specificity of 77%.

CONCLUSIONS

Analysis of strain-volume loops could provide unique information for predicting response to CRT. Assessment of septal myocardial wasted work at baseline is helpful to improve patient selection for CRT.