Role of Tissue Doppler and Strain Echocardiography in Current Clinical Practice

Comparison of Outcomes in Patients With Nonobstructive, Labile-Obstructive, and Chronically Obstructive Hypertrophic Cardiomyopathy

Patients with nonobstructive hypertrophic cardiomyopathy (HC) are considered low risk, generally not requiring aggressive intervention. However, nonobstructive and labile-obstructive HC have been traditionally classified together, and it is unknown if these 2 subgroups have distinct risk profiles. We compared cardiovascular outcomes in 293 patients HC (96 nonobstructive, 114 labile-obstructive, and 83 obstructive) referred for exercise echocardiography and magnetic resonance imaging and followed for 3.3 ± 3.6 years. A subgroup (34 nonobstructive, 28 labile-obstructive, 21 obstructive) underwent positron emission tomography. The mean number of sudden cardiac death risk factors was similar among groups (nonobstructive: 1.4 vs labile-obstructive: 1.2 vs obstructive: 1.4 risk factors, p = 0.2). Prevalence of late gadolinium enhancement (LGE) was similar across groups but more non-obstructive patients had late gadolinium enhancement ≥20% of myocardial mass (23 [30%] vs 19 [18%] labile-obstructive and 8 [11%] obstructive, p = 0.01]. Fewer labile-obstructive patients had regional positron emission tomography perfusion abnormalities (12 [46%] vs nonobstructive 30 [81%] and obstructive 17 [85%], p = 0.003]. During follow-up, 60 events were recorded (36 ventricular tachycardia/ventricular fibrillation, including 30 defibrillator discharges, 12 heart failure worsening, and 2 deaths). Nonobstructive patients were at greater risk of VT/VF at follow-up, compared to labile obstructive (hazed ratio 0.18, 95% confidence interval 0.04 to 0.84, p = 0.03) and the risk persisted after adjusting for age, gender, syncope, family history of sudden cardiac death, abnormal blood pressure response, and septum ≥3 cm (p = 0.04). Appropriate defibrillator discharges were more frequent in nonobstructive (8 [18%]) compared to labile-obstructive (0 [0%], p = 0.02) patients. In conclusion, nonobstructive hemodynamics is associated with more pronounced fibrosis and ischemia than labile-obstructive and is an independent predictor of VT/VF in HC.

Fast assessment of long axis strain with standard cardiovascular magnetic resonance: a validation study of a novel parameter with reference values

BACKGROUND

Assessment of longitudinal function with cardiovascular magnetic resonance (CMR) is limited to measurement of systolic excursion of the mitral annulus (MAPSE) or elaborate strain imaging modalities. The aim of this study was to develop a fast assessable parameter for the measurement of long axis strain (LAS) with CMR.

METHODS

40 healthy volunteers and 125 patients with different forms of cardiomyopathy were retrospectively analyzed. Four different approaches for the assessment of LAS with CMR measuring the distance between the LV apex and a line connecting the origins of the mitral valve leaflets in enddiastole and endsystole were evaluated. Values for LAS were calculated according to the strain formula.

RESULTS

LAS derived from the distance of the epicardial apical border to the midpoint of the line connecting the mitral valve insertion points (LAS-epi/mid) proved to be the most reliable parameter for the assessment of LAS among the different approaches. LAS-epi/mid displayed the highest sensitivity (81.6 %) and specificity (97.5 %), furthermore showing the best correlation with feature tracking (FTI) derived transmural longitudinal strain (r = 0.85). Moreover, LAS-epi/mid was non-inferior to FTI in discriminating controls from patients (Area under the curve (AUC) = 0.95 vs. 0.94, p = NS). The time required for analysis of LAS-epi/mid was significantly shorter than for FTI (67 ± 8 s vs. 180 ± 14 s, p < 0.0001). Additionally, LAS-epi/mid performed significantly better than MAPSE (Delta AUC = 0.09; p < 0.005) and the ejection fraction (Delta AUC = 0.11; p = 0.0002). Reference values were derived from 234 selected healthy volunteers. Mean value for LAS-epi/mid was -17.1 ± 2.3 %. Mean values for men were significantly lower compared to women (-16.5 ± 2.2 vs. -17.9 ± 2.1 %; p < 0.0001), while LAS decreased with age.

CONCLUSIONS

LAS-epi/mid is a novel and fast assessable parameter for the analysis of global longitudinal function with non-inferiority compared to transmural longitudinal strain.

Cardiopulmonary function and scoliosis severity in idiopathic scoliosis children

PURPOSE

Idiopathic scoliosis is a structural lateral curvature of the spine of unknown etiology. The relationship between degree of spine curvature and cardiopulmonary function has not yet been investigated. The purpose of this study was to determine the association between scoliosis and cardiopulmonary characteristics.

METHODS

Ninety children who underwent preoperative pulmonary or cardiac evaluation at a single spine institution over 41 months were included. They were divided into the thoracic-dominant scoliosis (group A, n=78) and lumbar-dominant scoliosis (group B, n=12) groups. Scoliosis severity was evaluated using the Cobb method. In each group, relationships between Cobb angles and cardiopulmonary markers such as forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1/FVC, left ventricular ejection fraction, pulmonary artery flow velocity, and tissue Doppler velocities (E/E', E'/A') were analyzed by correlation analysis linear regression.

RESULTS

In group A, 72 patients (92.3%) underwent pulmonary function tests (PFTs), and 41 (52.6%) underwent echocardiography. In group B, 9 patients (75.0%) underwent PFT and 8 (66.7%) underwent echocardiography. Cobb angles showed a significant negative correlation with FVC and FEV1 in group A (both P<0.05), but no such correlation in group B, and a significant negative correlation with mitral E/A ratio (P<0.05) and tissue Doppler E'/A' (P<0.05) in group A, with a positive correlation with mitral E/A ratio (P<0.05) in group B.

CONCLUSION

Pulmonary and cardiac function was significantly correlated with the degree of scoliosis in patients with thoracic-dominant scoliosis. Myocardial diastolic function might be impaired in patients with the most severe scoliosis.

A maximum likelihood approach to diffeomorphic speckle tracking for 3D strain estimation in echocardiography

The strain and strain-rate measures are commonly used for the analysis and assessment of regional myocardial function. In echocardiography (EC), the strain analysis became possible using Tissue Doppler Imaging (TDI). Unfortunately, this modality shows an important limitation: the angle between the myocardial movement and the ultrasound beam should be small to provide reliable measures. This constraint makes it difficult to provide strain measures of the entire myocardium. Alternative non-Doppler techniques such as Speckle Tracking (ST) can provide strain measures without angle constraints. However, the spatial resolution and the noisy appearance of speckle still make the strain estimation a challenging task in EC. Several maximum likelihood approaches have been proposed to statistically characterize the behavior of speckle, which results in a better performance of speckle tracking. However, those models do not consider common transformations to achieve the final B-mode image (e.g. interpolation). This paper proposes a new maximum likelihood approach for speckle tracking which effectively characterizes speckle of the final B-mode image. Its formulation provides a diffeomorphic scheme than can be efficiently optimized with a second-order method. The novelty of the method is threefold: First, the statistical characterization of speckle generalizes conventional speckle models (Rayleigh, Nakagami and Gamma) to a more versatile model for real data. Second, the formulation includes local correlation to increase the efficiency of frame-to-frame speckle tracking. Third, a probabilistic myocardial tissue characterization is used to automatically identify more reliable myocardial motions. The accuracy and agreement assessment was evaluated on a set of 16 synthetic image sequences for three different scenarios: normal, acute ischemia and acute dyssynchrony. The proposed method was compared to six speckle tracking methods. Results revealed that the proposed method is the most accurate method to measure the motion and strain with an average median motion error of 0.42 mm and a median strain error of 2.0 ± 0.9%, 2.1 ± 1.3% and 7.1 ± 4.9% for circumferential, longitudinal and radial strain respectively. It also showed its capability to identify abnormal segments with reduced cardiac function and timing differences for the dyssynchrony cases. These results indicate that the proposed diffeomorphic speckle tracking method provides robust and accurate motion and strain estimation.

Tissue Velocities and Myocardial Deformation in Asymptomatic and Symptomatic Aortic Stenosis

BACKGROUND

Assessment of myocardial longitudinal function has proved to be a sensitive marker of deteriorating myocardial function in aortic stenosis, demonstrated by both color Doppler tissue imaging and recently by two-dimensional speckle-tracking echocardiography. The aim of this study was to compare velocity (color Doppler tissue imaging) and deformation (two-dimensional speckle-tracking echocardiography) in relation to global and regional longitudinal function in asymptomatic and severe symptomatic aortic stenosis.

METHODS

In a cross-sectional design, 231 patients with aortic stenosis were divided into four groups: asymptomatic moderate aortic stenosis (aortic valve area, 1.0-1.5 cm(2); n = 38), asymptomatic severe aortic stenosis (aortic valve area < 1.0 cm(2); n = 66), and symptomatic severe aortic stenosis with preserved (n = 68) and reduced (<50%) left ventricular ejection fraction (n = 59).

RESULTS

Among all global (peak systolic s', diastolic e' and a', longitudinal displacement, and global longitudinal strain and strain rate) and regional longitudinal (basal, middle, and apical longitudinal strain and strain rate) parameters, only diastolic e', longitudinal displacement, and basal longitudinal strain (BLS) remained significantly associated with symptomatic status, independent of age, gender, heart rate, aortic valve area, stroke volume index, left ventricular mass index, left atrial volume index, and tricuspid annular systolic plane excursion. Furthermore, in a model with the aforementioned parameters, including e', longitudinal displacement, and BLS, only BLS remained significantly associated with symptomatic status in the entire study population (BLS per one-unit decrease: odds ratio, 1.23; 95% CI, 1.04-1.46; P = .017). Furthermore, patients with BLS < 13% were more likely to be symptomatic (odds ratio, 4.97; 95% CI, 2.6-9.4; P < .001), and no patients with asymptomatic severe aortic stenosis with BLS ≥ 13% were admitted with myocardial infarction or heart failure during follow-up of 1,462 days.

CONCLUSIONS

Among the many echocardiographic measures of longitudinal velocity and deformation, BLS has the strongest association with symptomatic status in aortic stenosis, and BLS < 13% is related to adverse outcomes in severe asymptomatic aortic stenosis.

"Reverse McConnell's Sign": Interpreting Interventricular Hemodynamic Dependency and Guiding the Management of Acute Heart Failure during Takotsubo Cardiomyopathy

Although most patients with Takotsubo cardiomyopathy (TTC) have benign clinical course and prognosis, TTC can induce acute heart failure and hemodynamic instability. TTC mimics the clinical features of acute anterior wall myocardial infarction (AMI). Bedside clinicians often have a diagnostic dilemma when cardiac catheterization and angiography are either contraindicated or can cause potential adverse consequences. Misdiagnosing TTC as AMI will lead to initiation of harmful pharmacological or device-based treatment, which worsens hemodynamic compromise. Therefore, understanding and interpreting the unique pathophysiological and hemodynamic features of TTC in a better manner becomes crucial to guide effective clinical management of acute heart failure/cardiogenic shock during TTC. We review recent advances in echocardiographic diagnosis of TTC and its role in guiding bedside management of acute heart failure and cardiogenic shock, with specific focus on the interpretation of discrepant, but reciprocally dependent, left and right ventricular hemodynamics during acute stages of TTC.

The use of strain, strain rate, and displacement by 2D speckle tracking for assessment of systolic left ventricular function in goats: applicability and influence of general anesthesia

Background

Assessment of left ventricular (LV) systolic function can be achieved by conventional echocardiographic methods, but quantification of contractility, regional myocardial function, and ventricular synchrony is challenging. The goal of this study was to investigate the applicability of two-dimensional speckle tracking (2DST) to characterize segmental and global wall motion for assessment of LV function and LV synchrony in healthy goats. We aimed to describe the techniques, report normal values of a variety of 2DST indices, and determine the influence of general anesthesia.

Methods

Prospective study on 22 healthy female Saanen goats (3.7 ± 1.1 y, 60.2 ± 10.5 kg [mean ± SD]). All goats underwent two transthoracic echocardiographic examinations, the first standing and unsedated and the second 7.4 ± 3.5 days later during isoflurane anesthesia and positioned in sternal recumbency. Data analyses were performed offline, blinded, and in random order. Left ventricular longitudinal, radial and circumferential strain and strain rate as well as longitudinal and radial displacement were measured using 2DST methods. Summary statistics were generated and differences of 2DST variables between myocardial segments and treatments (i.e., awake vs. anesthetized) were assessed statistically (alpha level=0.05).

Results

Echocardiographic analyses by 2DST were feasible in all goats and at both time points. Longitudinal systolic strain, strain rate and displacement followed a gradient from apex to base. Absolute systolic strain was generally lower and strain rate was higher in awake goats compared to anesthetized goats. Circumferential and radial indices did not consistently follow a segmental pattern. Generally, peak strain occurred later in anesthetized goats compared to awake goats. General anesthesia did not significantly influence LV synchrony.

Conclusions

2SDT is a valid method for non-invasive characterization of LV wall motion in awake and anesthetized goats. The results of this study add to the understanding of LV mechanical function, aid in the diagnosis of global and segmental LV systolic dysfunction, and will be useful for future cardiovascular studies in this species. However, effects of anesthesia and species-specific characteristics should be considered when goats are used as animal models for human disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12947-015-0005-8) contains supplementary material, which is available to authorized users.

Prognostic significance of semiautomatic quantification of left ventricular long axis shortening in systemic light-chain amyloidosis

AIMS

To assess left ventricular long axis shortening (LAS) in patients with AL amyloidosis as a potential predictor for outcome.

METHODS AND RESULTS

We performed a de novo echocardiographic analysis of LAS in 120 patients with biopsy-proven AL amyloidosis evaluated at first presentation before specific treatment. Additionally, 47 control subjects were analyzed retrospectivly. LAS was measured using a semiautomatic tissue motion annular displacement software algorithm (TMAD). LAS was significantly better than ejection fraction (EF) (p < 0.0001) and M-mode-derived mitral annular plane systolic excursion (MAPSE) (p < 0.05) discriminating AL patients from control subjects, while being non-inferior compared to tissue Doppler-derived peak systolic mitral annular velocity. One year outcome analysis in patients with AL amyloidosis showed that LAS remained the only significant echocardiographic parameter (HR:0.76; p < 0.005) in a multivariable Cox regression model of echocardiographic values. In a comprehensive clinical model, LAS (HR:0.72, p < 0.0001), cardiac troponin-T (HR:2.86, p < 0.01) and free light chain difference (HR:1.00; p < 0.05) were independently associated with the outcome. Assessment of LAS led to a significant integrated discrimination improvement and offered incremental information compared to EF and biomarkers. The cut-off value for LAS discriminating the endpoint was 5.8%.

CONCLUSION

LAS was an independent predictor of survival within the first year and offers incremental information in patients with AL amyloidosis evaluated prior to specific treatment.

Evaluation of early cardiac dysfunction in patients with systemic lupus erythematosus with or without anticardiolipin antibodies

The aim of this study was to use transthoracic Doppler echocardiographic (TTE) imaging methods to identify cardiac dysfunction, an indicator of subclinical atherosclerosis in asymptomatic systemic lupus erythematosus (SLE) patients in terms of cardiac effects. This study involved 80 patients: a study group ( n = 50) and control group ( n = 30). They were categorized into four subgroups: anticardiolipin antibodies (aCL) (+) ( n = 14) and aCL (−) ( n = 36); systemic lupus erythematosus disease activity index (SLEDAI) ≥ 6 ( n = 15) and SLEDAI < 6 ( n = 35); disease period ≥ 5 years ( n = 21) and disease period < 5 years ( n = 29); major organ involvement (+) ( n = 19), major organ involvement (−) ( n = 31). The ratio of mitral peak velocity of early filling to early diastolic mitral annular velocity (E/E′) for the study group was found to be higher than the control ( p < 0.01). Systolic septal motion velocity (Ssm) was lower in the study group compared with the control ( p < 0.01). Left atrium (LA) dimension was greater in the study group than the control ( p < 0.01). Ssm was found to be lower in the aCL (+) patients compared with the control and aCL (−) groups ( p < 0.01, p < 0.05, respectively). LA dimension was greater in the aCL (+) and (−) groups compared with the control, ( p < 0.01, p < 0.05, respectively) and aCL groups compared with each other ( p < 0.05). The E/E′ ratio for the aCL (+) and (−) groups was found to be greater than the control ( p < 0.05). In the study, both the Ssm and the late diastolic septal velocity (sA′) was found to be lower in the SLEDAI ≥6 group compared with SLEDAI<6 group, ( p < 0.001, p < 0.05, respectively). LA dimension was statistically greater in the SLEDAI ≥6 group compared with the SLEDAI <6 group ( p < 0.001). E′ and early diastolic septal velocity (sE′) were statistically lower in the disease period >5 years group compared with the disease period <5 years group ( p < 0.01, p < 0.05, respectively). Carrying out regular scans with TTE image of SLE patients is important in order to identify early cardiac involvement during monitoring and treatment. Identifying early cardiac involvement in SLE may lead to a reduction in mortality and morbidity rates.

Evaluation of Right Ventricular Myocardial Mechanics Using Velocity Vector Imaging of Cardiac MRI Cine Images in Transposition of the Great Arteries Following Atrial and Arterial Switch Operations

OBJECTIVE

The aim of the study was to determine right and left ventricle deformation parameters in patients with transposition of the great arteries who had undergone atrial or arterial switch procedures.

SETTING

Patients with transposition are born with a systemic right ventricle. Historically, the atrial switch operation, in which the right ventricle remains the systemic ventricle, was performed. These patients have increased rates of morbidity and mortality. We used cardiac MRI with Velocity Vector Imaging analysis to characterize and compare ventricular myocardial deformation in patients who had an atrial switch or arterial switch operation.

DESIGN

Patients with a history of these procedures, who had a clinically ordered cardiac MRI were included in the study. Consecutive 20 patients (75% male, 28.7 ± 1.8 years) who underwent atrial switch operation and 20 patients (60% male, 17.7 ± 1.9 years) who underwent arterial switch operation were included in the study. Four chamber and short-axis cine images were used to determine longitudinal and circumferential strain and strain rate using Vector Velocity Imaging software.

RESULTS

Compared with the arterial switch group, the atrial switch group had decreased right ventricular ejection fraction and increased end-diastolic and end-systolic volumes, and no difference in left ventricular ejection fraction and volumes. The atrial switch group had decreased longitudinal and circumferential strain and strain rate. When compared with normal controls multiple strain parameters in the atrial switch group were reduced.

CONCLUSIONS

Myocardial deformation analysis of transposition patients reveals a reduction of right ventricular function and decreased longitudinal and circumferential strain parameters in patients with an atrial switch operation compared with those with arterial switch operation. A better understanding of the mechanisms of right ventricle failure in transposition of great arteries may lead to improved therapies and adaptation.

Assessment of global longitudinal strain using standardized myocardial deformation imaging: a modality independent software approach

BACKGROUND

Myocardial deformation measurement is superior to left ventricular ejection fraction in identifying early changes in myocardial contractility and prediction of cardiovascular outcome. The lack of standardization hinders its clinical implementation. The aim of the study is to investigate a novel standardized deformation imaging approach based on the feature tracking algorithm for the assessment of global longitudinal (GLS) and global circumferential strain (GCS) in echocardiography and cardiac magnetic resonance imaging (CMR).

METHODS

70 subjects undergoing CMR were consecutively investigated with echocardiography within a median time of 30 min. GLS and GCS were analyzed with a post-processing software incorporating the same standardized algorithm for both modalities. Global strain was defined as the relative shortening of the whole endocardial contour length and calculated according to the strain formula.

RESULTS

Mean GLS values were -16.2 ± 5.3 and -17.3 ± 5.3 % for echocardiography and CMR, respectively. GLS did not differ significantly between the two imaging modalities, which showed strong correlation (r = 0.86), a small bias (-1.1 %) and narrow 95 % limits of agreement (LOA ± 5.4 %). Mean GCS values were -17.9 ± 6.3 and -24.4 ± 7.8 % for echocardiography and CMR, respectively. GCS was significantly underestimated by echocardiography (p < 0.001). A weaker correlation (r = 0.73), a higher bias (-6.5 %) and wider LOA (± 10.5 %) were observed for GCS. GLS showed a strong correlation (r = 0.92) when image quality was good, while correlation dropped to r = 0.82 with poor acoustic windows in echocardiography. GCS assessment revealed only a strong correlation (r = 0.87) when echocardiographic image quality was good. No significant differences for GLS between two different echocardiographic vendors could be detected.

CONCLUSIONS

Quantitative assessment of GLS using a standardized software algorithm allows the direct comparison of values acquired irrespective of the imaging modality. GLS may, therefore, serve as a reliable parameter for the assessment of global left ventricular function in clinical routine besides standard evaluation of the ejection fraction.

Quantification of regional myocardial wall motion by cardiovascular magnetic resonance

Cardiovascular magnetic resonance (CMR) is a versatile tool that also allows comprehensive and accurate measurement of both global and regional myocardial contraction. Quantification of regional wall motion parameters, such as strain, strain rate, twist and torsion, has been shown to be more sensitive to early-stage functional alterations. Since the invention of CMR tagging by magnetization saturation in 1988, several CMR techniques have been developed to enable the measurement of regional myocardial wall motion, including myocardial tissue tagging, phase contrast mapping, displacement encoding with stimulated echoes (DENSE), and strain encoded (SENC) imaging. These techniques have been developed with their own advantages and limitations. In this review, two widely used and closely related CMR techniques, i.e., tissue tagging and DENSE, will be discussed from the perspective of pulse sequence development and image-processing techniques. The clinical and preclinical applications of tissue tagging and DENSE in assessing wall motion mechanics in both normal and diseased hearts, including coronary artery diseases, hypertrophic cardiomyopathy, aortic stenosis, and Duchenne muscular dystrophies, will be discussed.

The effect of recombinant human growth hormone therapy on left-ventricular chamber size and function in children with growth hormone deficiency

This study was designed to assess the effect of recombinant human growth hormone (rhGH) therapy on left-ventricular (LV) chamber size and function in children with idiopathic isolated growth hormone deficiency (GHD) using conventional echocardiography and tissue Doppler imaging (TDI). Thirty patients (19 boys and 11 girls) with idiopathic isolated GHD were followed-up for 12 months. Mean age of patients was 11.0 ± 2.6 years (range 6.3-15.5). At baseline and at 3, 6, and 12 months of treatment, the structure of the left ventricle was assessed by conventional echocardiography and myocardial rates and time intervals by TDI. There was a significant increase in LV mass (LVM) compared with pretreatment values. Like LVM, relative wall thickness (RWT) was also increased significantly. The significant increase in LVM indexed to body surface area and RWT became apparent at month 3 of treatment with a significant increase in LVM indexed to height(2.7) at treatment month 6. Normalized LVM increased as early month 3 of treatment, and a steady increase was observed until month 12. However, no patient had LVM > +2 standard deviation scores at month 12 of treatment. No significant differences were observed in functional parameters of the left ventricle and the interventricular septum. The results of this study showed that rhGH therapy causes an increase in myocardial mass without changing the geometry or function of the myocardium. Therefore, the increase in myocardial mass appears to be concentric, thus causing remodeling instead of hypertrophy.

Structural and functional cardiac adaptations to 6 months of football training in untrained hypertensive men

We investigated the effects of 3 and 6 months of regular football training on cardiac structure and function in hypertensive men. Thirty-one untrained males with mild-to-moderate hypertension were randomized 2:1 to a football training group (n = 20) and a control group receiving traditional recommendations on healthy lifestyle (n = 11). Cardiac measures were evaluated by echocardiography. The football group exhibited significant (P < 0.05) changes in cardiac dimensions and function after just 3 months: Left ventricular (LV) end-diastolic volume increased from 104 ± 25 to 117 ± 29 mL. LV diastolic function improved measured as E/A ratio (1.15 ± 0.32 to 1.54 ± 0.38), early diastolic velocity, E' (11.0 ± 2.5 to 11.9 ± 2.6 cm/s), and isovolumetric relaxation time (74 ± 13 to 62 ± 13 ms). LV systolic function improved measured as longitudinal displacement (10.7 ± 2.1 to 12.1 ± 2.3 mm). Right ventricular function improved with respect to tricuspid annular plane systolic excursion (21.8 ± 3.2 to 24.5 ± 3.7 mm). Arterial blood pressure decreased in both groups, but significantly more in the football training group. No significant changes were observed in the control group. In conclusion, short-term football training improves LV diastolic function in untrained men with mild-to-moderate arterial hypertension. Furthermore, it may improve longitudinal systolic function of both ventricles. The results suggest that football training has favorable effects on cardiac function in hypertensive men.

Reproducibility of regional and global longitudinal strains derived from two-dimensional speckle-tracking and doppler tissue imaging between expert and novice readers during quantitative dobutamine stress echocardiography

BACKGROUND

Longitudinal strain (LS) is a quantitative parameter that adds incremental value to wall motion analysis. The aim of this study was to compare the reproducibility of LS derived from Doppler tissue imaging and speckle-tracking between an expert and a novice strain reader during dobutamine stress echocardiography (DSE).

METHODS

Forty-one patients (mean age, 65 ± 15 years; mean ejection fraction, 58 ± 11%) underwent DSE per clinical protocol. Global LS derived from speckle-tracking and regional LS derived from both speckle-tracking and Doppler tissue imaging were measured twice by an expert strain reader and also measured twice by a novice strain reader. Intraobserver and interobserver analyses were performed using intraclass correlation coefficients (ICC), Bland-Altman analysis, and absolute difference values (mean ± SD).

RESULTS

Global LS measured by the expert strain reader demonstrated high intraobserver measurement reproducibility (rest: ICC = 0.95, absolute difference = 5.5 ± 4.9%; low dose: ICC = 0.96, absolute difference = 5.7 ± 3.7%; peak dose: ICC = 0.87, absolute difference = 11.4 ± 8.4%). Global LS measured by the novice strain reader also demonstrated high intraobserver reproducibility (rest: ICC = 0.97, absolute difference = 4.1 ± 3.4%; low dose: ICC = 0.94, absolute difference = 5.4 ± 5.9%; peak dose: ICC = 0.94, absolute difference = 6.1 ± 4.8%). Global LS also showed high interobserver agreement between the expert and novice readers at all stages of DSE (rest: ICC = 0.90, absolute difference = 8.5 ± 7.5%; low dose: ICC = 0.90, absolute difference = 8.9 ± 7.1%; peak dose: ICC = 0.87, absolute difference = 10.8 ± 8.4%). Of all parameters studied, LS derived from Doppler tissue imaging had relatively low interobserver and intraobserver agreement.

CONCLUSIONS

Global LS is highly reproducible during all stages of DSE. This variable is a potentially reliable and reproducible measure of myocardial deformation.

A new technique for the estimation of cardiac motion in echocardiography based on transverse oscillations: a preliminary evaluation in silico and a feasibility demonstration in vivo

Quantification of regional myocardial motion and deformation from cardiac ultrasound is fostering considerable research efforts. Despite the tremendous improvements done in the field, all existing approaches still face a common limitation which is intrinsically connected with the formation of the ultrasound images. Specifically, the reduced lateral resolution and the absence of phase information in the lateral direction highly limit the accuracy in the computation of lateral displacements. In this context, this paper introduces a novel setup for the estimation of cardiac motion with ultrasound. The framework includes an unconventional beamforming technique and a dedicated motion estimation algorithm. The beamformer aims at introducing phase information in the lateral direction by producing transverse oscillations. The estimator directly exploits the phase information in the two directions by decomposing the image into two 2-D single-orthant analytic signals. An in silico evaluation of the proposed framework is presented on five ultra-realistic simulated echocardiographic sequences, where the proposed motion estimator is contrasted against other two phase-based solutions exploiting the presence of transverse oscillations and against block-matching on standard images. An implementation of the new beamforming strategy on a research ultrasound platform is also shown along with a preliminary in vivo evaluation on one healthy subject.

Neonatal cardiac dysfunction in intrauterine growth restriction

BACKGROUND

The early postnatal cardiovascular consequences of intrauterine growth restriction (IUGR) have not been completely elucidated. This study aimed to evaluate the effect of IUGR on neonatal myocardial function and cardiovascular adaptation to extrauterine life.

METHODS

Conventional and tissue Doppler echocardiographic parameters were compared on the second and fifth postnatal day between 30 IUGR and 30 appropriate-for-gestational age (AGA) neonates.

RESULTS

IUGR neonates presented relative interventricular septum (IVS) hypertrophy (IVS to left ventricular (LV) posterior wall diastolic ratio: median IUGR-AGA difference of 0.05 (interquartile range: 0.04-0.06); P = 0.020), relative LV dilatation (wall thickness to end-diastolic LV dimension difference of 0.12 (0.06-0.16); P = 0.012), and increased left myocardial performance index (MPI difference of 0.19 (0.05-0.28); P = 0.012). Repeated measurements ANOVA revealed a different pattern of change in LV stroke volume (LVSV; P < 0.001), LV cardiac output (LVCO; P < 0.001), MPI (P < 0.001), and heart rate (HR; P = 0.025) between AGA and IUGR infants. From the second to the fifth postnatal day, AGA neonates presented a decrease in MPI and HR with an increase in LVSV and LVCO. IUGR neonates failed to achieve similar changes in MPI, HR, and LVSV, whereas their LVCO decreased.

CONCLUSION

IUGR neonates present changes in cardiac morphology and subclinical myocardial dysfunction, which may result in an altered pattern of cardiovascular adaptation to extrauterine life.

Subclinical Myocardial Disease in Heart Failure Detected by CMR

Noninvasive cardiac imaging plays a central role in the assessment of patients with heart failure at all stages of disease. Moreover, this role can be even more important for individuals with asymptomatic cardiac functional or structural abnormalities-subclinical myocardial disease - because they could have benefits from early interventions before the onset of clinical heart failure. In this sense, cardiac magnetic resonance offers not only precise global cardiac function and cardiac structure, but also more detailed regional function and tissue characterization by recent developing methods. In this section, some of the main methods available for subclinical myocardial disease detection are reviewed in terms of what they can provide and how they can improve heart failure assessment.

Strain improves risk prediction beyond ejection fraction in chronic systolic heart failure

Background

The utility of longitudinal, circumferential, and radial strain and strain rate in determining prognosis in chronic heart failure is not well established.

Methods and Results

In 416 patients with chronic systolic heart failure, we performed speckle‐tracking analyses of left ventricular longitudinal, circumferential, and radial strain and strain rate on archived echocardiography images (30 frames per second). Cox regression models were used to determine the associations between strain and strain rate and risk of all‐cause mortality, cardiac transplantation, and ventricular‐assist device placement. The area under the time‐dependent ROC curve (AUC) was also calculated at 1 year and 5 years. Over a maximum follow‐up of 8.9 years, there were 138 events (33.2%). In unadjusted models, all strain and strain rate parameters were associated with adverse outcomes (P<0.001). In multivariable models, all parameters with the exception of radial strain rate (P=0.11) remained independently associated, with patients in the lowest tertile of strain or strain rate parameter having a ≈2‐fold increased risk of adverse outcomes compared with the reference group (P<0.05). Addition of strain to ejection fraction (EF) led to a significantly improved AUC at 1 year (0.697 versus 0.633, P=0.032) and 5 years (0.700 versus 0.638, P=0.001). In contrast, strain rate did not provide incremental prognostic value to EF alone.

Conclusions

Longitudinal and circumferential strain and strain rate, and radial strain are associated with chronic heart failure prognosis. Strain provides incremental value to EF in the prediction of adverse outcomes, and with additional study may be a clinically relevant prognostic tool.

Characterization of normal regional myocardial function by MRI cardiac tagging

PURPOSE

The aim of this study was to establish reference values for segmental myocardial strain measured by magnetic resonance (MR) cardiac tagging in order to characterize the regional function of the heart.

MATERIAL AND METHODS

We characterized the left ventricular (LV) systolic deformation in 39 subjects (26 women and 13 men, age 58.8 ± 11.6 years) whose cardiological study had not revealed any significant abnormality. The deformation was measured from MR-tagged (Siemens 1.5T MR) images using an algorithm based on sine wave modeling. Circumferential and radial peak systolic strain values along with the torsion angle and circumferential-longitudinal (CL) shear were determined in 16 LV segments in order to settle the reference values for these parameters.

RESULTS

Circumferential strain was highest at the anterior and lateral walls (-20.2 ± 4.0% and -21.8 ± 4.3%, respectively; P < 0.05) and was lowest at the base level (-17.2 ± 3.1% vs. -20.1 ± 3.1% "mid level," P < 0.05; -17.2 ± 3.1% vs. -20.3 ± 3.0% "apical level," P < 0.05). Radial strain highest values were from inferior and lateral walls (13.7 ± 7.4% and 12.8 ± 7.8%, respectively; P < 0.05) and it was lowest medially (9.4 ± 4.1% vs. 13.1 ± 4.1% "base level," P < 0.05; 9.4 ± 4.1% vs. 12.1 ± 4.4% "apical level," P < 0.05). Torsion angle (counterclockwise when viewed from the apex) increased with the distance from the base (7.9 ± 2.4° vs. 16.8 ± 4.4°, P < 0.05), and the highest and lowest values were found at lateral (medial lateral: 12.0 ± 4.4°, apical lateral: 25.1 ± 6.4°, P < 0.05) and septal wall (medial septal: 3.6 ± 2.1°, apical septal: 8.3 ± 5.3°, P < 0.05), respectively. These differences were found again in CL shear values, around the LV circumference. However, CL shear remained constant with increasing distance from the base (9.1 ± 2.6°, medium and 9.8 ± 2.4°, apex).

CONCLUSION

In summary, this study provides reference values for the assessment of regional myocardial function by MR cardiac tagging. Comparison of patient deformation parameters with normal deformation patterns may permit early detection of regional systolic dysfunction.

Evaluation of left ventricular diastolic function by global strain rate imaging in patients with obstructive hypertrophic cardiomyopathy: a simultaneous speckle tracking echocardiography and cardiac catheterization study

BACKGROUND

Impaired left ventricular (LV) diastolic function is a common pathophysiological feature of patients with hypertrophic cardiomyopathy (HCM). The noninvasive evaluation of diastolic function in these patients remains a challenge. Speckle tracking echocardiography (STE) provides direct information on intrinsic myocardial function and may improve the diagnostic of diastolic dysfunction in HCM patients.

METHODS AND RESULTS

We retrospectively analyzed 51 patients with obstructive HCM (HOCM). Strain rate (SR) curves were obtained for 18 different segments of the LV myocardium. The peak SR during the isovolumic relaxation period (SRIVR ) and the peak early diastolic strain rate (SRE ) were measured for each segment. Cardiac catheterization was performed within 24 hours after echocardiographic analysis. LV end-diastolic pressure (LVEDP) was measured and time constant of myocardial relaxation (τ) was calculated. We therefore correlated STE-derived with invasive indices and compared it with flow and tissue Doppler measurements. SRIVR and SRE were significantly reduced in all 51 HOCM patients (0.16 ± 0.09%/sec and 0.71 ± 0.25%/sec).The ratio of peak early mitral inflow velocities to SRIVR and SRE (E/SRIVR and E/SRE ) correlated well with LVEDP (r = 0.760, P < 0.001; r = 0.401, P = 0.004). Receiver operating characteristic analysis shown E/SRE ratio had the largest under curve area in predicting HOCM patients with seriously elevated LVEDP. In addition, SRIVR and SRE significantly related with τ (r = -0.611, P < 0.001; r = -0.369, P = 0.008).

CONCLUSIONS

Diastolic function was seriously impaired in HOCM patients. The E/SRE ratio can be used to predict LVEDP with acceptable accurate in HOCM patients. In addition, SRIVR is a reliable parameter to assess LV relaxation in patients with HOCM.

Comparison of clinical presentation, left ventricular morphology, hemodynamics, and exercise tolerance in obese versus nonobese patients with hypertrophic cardiomyopathy

Obesity is independently associated with left ventricular (LV) hypertrophy and thus may be an important modifier of the hypertrophic cardiomyopathy (HC) phenotype. We examined if obesity modifies the clinical presentation, LV morphology, outflow hemodynamics, and exercise tolerance in HC. In this cross-sectional study, 88 obese (body mass index [BMI] ≥30 kg/m(2)) and 154 nonobese (BMI <30 kg/m(2)) patients from the Johns Hopkins HC clinic were compared with respect to a variety of clinical and LV echocardiographic measurements. Obese patients (36.4%) were more likely to report exertional dyspnea (p = 0.04) and chest pain (p = 0.002) and had greater prevalence of hypertension (p = 0.008). LV posterior wall thickness (p = 0.01) but not the septal wall (p ≥0.21) was significantly greater in obese patients, resulting in an increased LV mass index (p = 0.003). No significant differences in LV systolic and diastolic functions were observed, but obesity was associated with higher LV stroke volume (p = 0.03), inducible LV outflow tract gradients (p = 0.045), and chance of developing LV outflow tract obstruction during stress (p = 0.035). In multivariate analysis, BMI was associated with increased posterior (but not septal) wall thickness (β = 0.15, p = 0.02) and LV mass index (β = 0.18, p = 0.005), particularly in those with hypertension. Obesity was also associated with reduced exercise time and functional capacity, and BMI independently correlated with reduced exercise tolerance. In conclusion, obesity is associated with larger LV mass, worse symptoms, lower exercise tolerance, and labile obstructive hemodynamics in HC. The association with increased outflow tract gradients has particular importance as contribution of obesity to the pressure gradients may influence clinical decisions in labile obstructive HC.

Cardiac assessment in pediatric mice: strain analysis as a diagnostic measurement

Echocardiography is a robust tool for assessing cardiac function in both humans and laboratory animals. Conventional echocardiographic measurements, including chamber dimensions, wall thickness, and ejection fraction are routinely obtained to assess cardiac function in mice. Recently, myocardial strain and strain rate measurements have been added to functional assessments to provide additional details on regional abnormalities that are not evident using conventional measurements. To date, all studies of strain and strain rate in mice or rats have involved adult animals. This study serves to outline methods for acquiring echocardiographic images in pediatric mice and to provide myocardial strain and strain rate values for healthy C57BL/6J mice between 3 and 11 weeks old. Between weeks 3 and 11, left ventricular radial strain ranged from 32 to 43% and longitudinal strain ranged from -15 to -19%, with analysis over time showing no significant changes with aging (radial strain, P = 0.192 and longitudinal strain, P = 0.264; n = 4 for each time point evaluated). In conclusion, myocardial strain analysis in pediatric mice is technically feasible and has potential application in studying the pathophysiology of pediatric cardiovascular disease.

Imaging techniques for cardiac strain and deformation: comparison of echocardiography, cardiac magnetic resonance and cardiac computed tomography

Myocardial function assessment is essential for determining the health of the myocardium. Global assessment of myocardial function is widely performed (by estimating the ejection fraction), but many common cardiac diseases initially affect the myocardium on a regional, rather than global basis. Regional myocardial wall motion can be quantified using myocardial strain analysis (a normalized measure of deformation). Myocardial strain can be measured in terms of three normal strains (longitudinal strain, radial strain and circumferential) and six shear strains. Cardiac MRI (cMRI) is usually considered the reference standard for measurement of myocardial strain. The most common cMRI method, termed tagged cMRI, allows full, 3D assessment of regional strain. However, due to its complexity and lengthy times for analysis, tagged cMRI is not usually used outside of academic centers. Tagged cMRI is also primarily used only in research studies. Echocardiography combined with tissue Doppler imaging or a speckle tracking technique is now widely available in the clinical setting. Myocardial strain measurement by echocardiography shows reasonable agreement with cMRI. Limited standardization and differences between vendors represent current limitations of the technique. Cardiac computed tomography (CCT) is the newest and most rapidly growing modality for noninvasive imaging of the heart. While CCT studies are most commonly applied to assess the coronary arteries, CCT is easily adapted to provide functional information for both the left and right ventricles. New methods for CCT assessment of regional myocardial function are being developed. This review outlines the current literature on imaging techniques related to cardiac strain analysis and discusses the strengths and weaknesses of various methods for myocardial strain analysis.

Evaluation of coronary steal in myocardium supplied by coronary collaterals: the role of speckle tracking analysis in resting and stress echocardiography

Coronary steal could develop in patients with chronic coronary artery disease (CAD) with collateral circulation, and adversely affect ventricular function and long-term clinical outcome. Poorly developed collaterals are more prone than well-developed collaterals to withdrawing their blood support to the collateralized myocardium due to higher collateral pathway resistance and lower vasodilatory reserve of the collateral bed. Even with well-developed coronary collaterals, coronary steal could still occur when perfusion pressure in the donor artery becomes low, or the recipient microvasculature is maximally dilated with exhaustion of vasodilatory reserve. The evaluation of distinctive coronary collateral function with or without steal provides important therapeutic and prognostic information in patients with chronic CAD. However, due to lack of reliable assessment methods, the detection and quantitative measurement of coronary steal remains a challenge. In this article, we present typical clinical scenarios to illustrate the major mechanisms underlying coronary steal in patients with chronic CAD and coronary collateral circulation, and review invasive and noninvasive methods currently available to assess coronary steal in myocardium supplied by coronary collaterals. We specifically focus on recent advances in the resting and stress echocardiography with speckle tracking techniques.

Mitral annular displacement by Doppler tissue imaging may identify coronary occlusion and predict mortality in patients with non-ST-elevation myocardial infarction

BACKGROUND

Mitral annular displacement (MAD) is a simple marker of left ventricular (LV) systolic function. The aim of this study was to test the hypothesis that MAD can distinguish patients with non-ST-segment elevation myocardial infarctions (NSTEMIs) from those with significant coronary artery disease without infarctions, identify coronary occlusion, and predict mortality in patients with NSTEMIs. MAD was compared with established indices of LV function.

METHODS

In this retrospective study, 167 patients with confirmed NSTEMIs were included at two Scandinavian centers. Forty patients with significant coronary artery disease but without myocardial infarctions were included as controls. Doppler tissue imaging was performed at the mitral level of the left ventricle in the three apical planes, and velocities were integrated over time to acquire MAD. LV ejection fraction, global longitudinal strain (GLS), and wall motion score index were assessed according to guidelines.

RESULTS

MAD and GLS could accurately distinguish patients with NSTEMIs from controls. During 48.6 ± 12.1 months of follow-up, 22 of 167 died (13%). MAD, LV ejection fraction, and GLS were reduced and wall motion score index was increased among those who died compared with those who survived (P < .001, P < .001, P < .001, and P = .02, respectively). Multivariate Cox proportional-hazards analyses revealed that MAD was an independent predictor of death (hazard ratio, 1.36; 95% confidence interval, 1.07-1.73; P = .01). MAD and GLS were reduced and wall motion score index was increased in patients with coronary artery occlusion compared with those without occlusion (P = .006, P = .001, and P = .02), while LV ejection fraction did not differ (P = .20).

CONCLUSIONS

MAD accurately identified patients with NSTEMIs, predicted mortality, and identified coronary occlusion in patients with NSTEMIs.

Methods for measuring right ventricular function and hemodynamic coupling with the pulmonary vasculature

The right ventricle (RV) is a pulsatile pump, the efficiency of which depends on proper hemodynamic coupling with the compliant pulmonary circulation. The RV and pulmonary circulation exhibit structural and functional differences with the more extensively investigated left ventricle (LV) and systemic circulation. In light of these differences, metrics of LV function and efficiency of coupling to the systemic circulation cannot be used without modification to characterize RV function and efficiency of coupling to the pulmonary circulation. In this article, we review RV physiology and mechanics, established and novel methods for measuring RV function and hemodynamic coupling, and findings from application of these methods to RV function and coupling changes with pulmonary hypertension. We especially focus on non-invasive measurements, as these may represent the future for clinical monitoring of disease progression and the effect of drug therapies.

Assessing pre-clinical ventricular dysfunction in obese children and adolescents: the value of speckle tracking imaging

AIMS

Obesity has become a major health problem worldwide. Cardiovascular abnormalities have been described not only in obese adults but also in obese children and adolescents. The aim of the present study was to investigate left and right, systolic and diastolic ventricular dysfunction in obese paediatric patients without comorbidities using 2D speckle tracking longitudinal strain.

METHODS AND RESULTS

Doppler echocardiogram was performed on 50 obese children and adolescents with body mass index (BMI) above the 95th percentile (OG) and 46 non-obese sex- and age-matched controls (CG). Systolic and diastolic functions of both ventricles were investigated through conventional Doppler echocardiography. Tissue Doppler imaging (TDI), colour Doppler myocardial imaging (CDMI), and two-dimensional (2D) speckle tracking were also used to analyse ventricular performance in both groups. Left-ventricular (LV) ejection fraction was similar between groups (68.2 ± 6.2 vs. 68.3 ± 5.3, P = 0.931). Left-ventricular diastolic parameters did not differ between groups, except for a lower mitral A wave (61.6 ± 13.0 vs. 51.9 ± 10.0 cm/s, P > 0.001) and higher E/A ratio (1.8 ± 0.5 vs. 2.1 ± 0.4, P = 0.007) in the controls. Left-ventricular global strain was lower in the OG by both methods (CDMI: 22.0 ± 2.8 vs. 24.6 ± 2.7%, P = 0.020; 2D speckle tracking: 18.4 ± 1.6 vs. 20.4 ± 1.7%, P < 0.001). In multivariate analysis, 2D longitudinal global strain correlated negatively with BMI, r = -0.433, p = 0.002.

CONCLUSION

Although EF was not different between the two groups, LV 2D speckle tracking longitudinal strain was lower in the obese group, even in the absence of other comorbidities, indicating that obesity effects on LV function is an early finding in obesity.

Decreased right ventricular function in healthy pediatric cystic fibrosis patients versus non-cystic fibrosis patients

Right ventricular (RV) dysfunction may occur in patients with cystic fibrosis (CF). Tissue Doppler imaging (TDI) and strain and strain rate analysis are new echocardiographic tools that can quantitate RV function. This study aimed to compare the RV function between healthy CF patients and non-CF patients to determine whether differences exist. Healthy CF children and age-matched non-CF children were enrolled in the study. In this study, TDI analysis of the RV free wall was performed at the level of the tricuspid valve annulus. Two-dimensional speckle echocardiography was used to measure global strain and strain rates in a six-segment model of the RV. Independent t tests were used to compare the groups. The study enrolled 18 CF patients (age, 7.7 ± 2.0 years) and 15 non-CF patients (age, 6.4 ± 2.5 years). The age difference was not significant. The forced expiratory volume in the first second (FEV(1)) for the CF patients was 91 ± 15 %. The systolic annular velocity by TDI was significantly lower in the CF group. The RV strain values in the CF group were significantly lower in four of the six segments (RV free-wall base, RV free-wall mid, RV septal apex, and RV septal mid). The global strain value, the systolic strain rate, and the early diastolic strain rate were significantly lower in the CF group. Decreased systolic and diastolic RV properties were present in young healthy CF patients. Further studies with longitudinal follow-up evaluation are needed to determine the significance of these findings for the pediatric CF population.

Functional changes of the myocardium in survivors of high-voltage electrical injury

Introduction

There are limited long-term follow-up data on functional changes in the myocardium after high-voltage electrical injury (HVEI).

Methods

Twenty-three patients who had been exposed to HVEI (>20,000 volts) and preserved left ventricular ejection fraction (≥55%) were enrolled in the study. Echocardiographic parameters, including peak systolic strain (S) and strain rate (SR), were evaluated at baseline, six weeks and six months later. These data were compared with a healthy control group who were matched in terms of age, sex and body mass index.

Results

The systolic and diastolic blood pressure and the heart rate were significantly higher in the HVEI group compared with the control group at baseline and at six weeks, but not at the six-month follow-up. Conventional echocardiographic data showed no differences between the groups during the study period. In contrast to the S, the baseline and six weeks, SR was significantly increased in the HVEI group compared with the control group. However, at the six-month follow-up, there was no difference in the SR between the groups. Among the 23 patients with HVEI, 17 of the patients had vertical current injury, and 6 patients had horizontal current injury. There was no difference in terms of the conventional echocardiography, S and SR between the patients with vertical injury and those with horizontal injury at baseline and at the six-month follow-up.

Conclusions

The long-term contractile performance of the myocardium is preserved when patient do not experience left ventricular dysfunction in the early stages after HVEI.

Mechanical loading promotes mast cell degranulation via RGD-integrin dependent pathways

Mast cells are known to respond to a number of stimuli, such as IgE antibody-antigen complexes, pathogens, chemical compounds, and physical stimulation, resulting in the activation of these cells and subsequent release of cytokines, inflammatory mediators and granules which can influence the pathophysiology of neighboring cells. Although different forms of physical stimulation (i.e. shear stress and acupuncture) have been investigated, the effect of cyclic tensile loading on mast cell activation has not. To characterize the response of mast cells to tensile loading, RBL-2H3 cells were embedded in a 3-dimensional fibrin construct and subjected to 24h of cyclic loading at 0%, 5% or 10% peak tensile strain. Mechanical loading significantly increased RBL-2H3 cell secretion of β-hexosaminidase (2.1- to 2.3-fold, respectively) in a load- and time-dependent manner when compared to the controls. Furthermore, no evidence of load-induced cell death or alterations in cell proliferation was observed. To determine if RGD-dependent integrins mediated the degranulation of mast cells during mechanical loading, cell-matrix interactions were inhibited by treating the cells with echistatin, a disintegrin that binds RGD-dependent integrins. Treatment with echistatin significantly attenuated load-induced degranulation without compromising cell viability. These results suggest a novel mechanism through which mechanical loading induces mast cell activation via RGD binding integrins.