Echocardiographic strain and strain rate imaging — Clinical applications

The role of 3D wall motion tracking in heart failure

Heart failure is a major health problem in developed countries and a growing one in developing countries. Cardiac remodeling in heart failure affects myocardial mechanics, which requires comprehensive evaluation in three dimensions. The novel technique of 3D wall motion tracking applies speckle tracking technology to full volume, 3D echocardiographic datasets. Quantification of conventional and novel left ventricular (LV) parameters including volumes, ejection fraction, global and regional 3D strain, endocardial area strain, twist, and dyssynchrony, and identification of the site of latest mechanical activation are feasible on the basis of a single acquisition of a full-volume dataset. Clinical applications of 3D wall motion tracking include the assessment of global and regional LV performance in ischemic and nonischemic heart diseases, evaluation of mechanics in cardiomyopathies and congenital heart disease, potential selection of patients for cardiac resynchronization therapy and prediction of their response, and detection of subclinical cardiac dysfunction in diseases with likelihood of progression to heart failure. Technological advances with improvement in spatial and temporal resolution of this novel imaging modality are expected. Although 3D wall motion tracking is still in its infancy, this method has begun to provide new insights into LV mechanics and has already found clinical applications. Future developments in 3D assessment of right ventricular and myocardial layer-specific mechanics are awaited.

Left ventricular myocardial performance assessed by 2-dimensional speckle tracking echocardiography in patients with sickle cell crisis

BACKGROUND

The status of left ventricle in sickle cell anemia presenting in sickle crisis and follow up has been minimally studied in past. To determine the left ventricular (LV) myocardial performance in these patients, we performed the study to assess two dimensional strains imaging which allowed a rapid and an accurate analysis of global and regional LV myocardial performance in longitudinal, radial, and circumferential directions.

METHODS

In this prospective study, 2-dimensional echocardiography (2DE) images of the LV were obtained in 52 subjects which included 32 patients (23 ± 8yrs, 16 male) with homozygous sickle cell anemia (SCA) in sickle cell crisis and 20 healthy controls (23 ± 5 yrs, 11 male) using apical 4-chamber and parasternal short-axis at the basal, mid, and apical levels. Of these 32 patients, 2DE was performed again in 18 patients in follow up (8 months ± 5 days). Longitudinal, circumferential and radial strains (LS, CS and RS respectively) were quantified and compared in an 18-segment model using a novel speckle tracking system (2D Cardiac Performance Analysis, TomTec Imaging System, Munich, Germany).

RESULTS

There was no significant difference in LV ejection fraction between both the groups (59.32 ± 12.6 vs. 52.3 ± 7.9; p-value > 0.05). In comparison with normal controls and follow up of sickle cell patients, peak LS was significantly attenuated in the subendocardial and subepicardial regions during sickle cell crisis (p < 0.05). However, a significant reduction in circumferential strain was evident only in subepicardial region (p < 0.001). Also patients in sickle cell crisis showed significantly higher radial strain parameters than controls (p < 0.001).

CONCLUSION

Patients with SCA presenting in sickle cell crisis have reduced longitudinal shortening. LV myocardial performance remains unaltered due to relatively preserved circumferential shortening and increased radial thickening.

Speckle tracking echocardiography in acute myocarditis

To evaluate 2-dimensional speckle tracking echocardiography as a diagnostic and prognostic tool in patients with acute myocarditis. In this retrospective cohort study, 45 patients (age, 39 ± 15 years; 32 male) with suspected acute myocarditis and 83 healthy controls (age, 39 ± 13 years; 27 male) underwent 2-dimensional speckle tracking echocardiography. Main outcome measures were circumferential and longitudinal strain and strain rate as prognostic and diagnostic markers. Patients with myocarditis had lower circumferential strain (-13.3 ± 5.6 % vs. -22.3 ± 4 %), circumferential strain rate (-0.9 ± 0.3 vs. -1.4 ± 0.3 s(-1)), longitudinal strain (-11.7 ± 4 % vs. -17.7 ± 1.9 %), and longitudinal strain rate (-0.7 ± 0.2 vs. -1.0 ± 0.1 s(-1)) (all P < .001). For diagnostic purposes, longitudinal strain had the greatest area under the curve, 0.93 (optimal cutoff value, -15.1 %; sensitivity, 78 %; specificity, 93 %). Future events were defined as cardiac death, heart transplant, placement of left ventricular assist device or implantable cardioverter-defibrillator, pulmonary edema-related respiratory failure, cardiogenic shock, and rehospitalization due to cardiac events. For every 1 % decline in longitudinal or circumferential strain, the hazard ratios (95 % CIs) were 1.26 (1.10-1.47) and 1.34 (1.14-1.63), respectively; for every 0.1 s(-1) decline in longitudinal or circumferential strain rate, the hazard ratios (95 % CIs) were 1.43 (1.09-1.89) and 1.52 (1.19-2.01), respectively (P < .01). Kaplan-Meier curve and log-rank test showed event-free survival significantly related to these 4 measurements. In acute myocarditis, left ventricular strain and strain rate may be promising diagnostic and prognostic tools, even in patients with preserved left ventricular ejection fraction. Most importantly, this imaging technique had a role in predicting deterioration and overall event-free survival.

A novel titin mutation in adult-onset familial dilated cardiomyopathy

Familial dilated cardiomyopathy is a major cause of advanced heart failure and heart transplantation. In most families, the disease-causing mutation is unknown, and relatives should therefore undergo periodic screening to facilitate early diagnosis and therapy. In the present study, we describe a novel titin truncation mutation causing adult-onset familial dilated cardiomyopathy in an Israeli Arab family. The family members underwent physical examination, electrocardiography, and Doppler echocardiography. Linkage to candidate loci was performed, followed by gene sequencing. We identified 13 clinically affected family members (8 men and 5 women, mean age 47 ± 12 years). Compared with their healthy first-degree relatives, the affected relatives had a larger end-diastolic left ventricular dimension (60 ± 10 vs 49 ± 4 mm, p <0.001), lower ejection fraction (43 ± 11% vs 60 ± 6%, p <0.001), and markedly higher end-systolic volume indexes but no difference in wall thickness or diastolic function. The linkage studies or direct sequencing excluded LMNA, MYH7, TNNT2, TNNI3, SCN5A, DES, SGCD, ACTC, PLN, and MYH6 but established linkage to the TTN locus at chromosome 2q31, yielding a maximum (2-point) LOD score of 3.44. Sequence analysis identified an insertion (c.58880insA), causing protein truncation after 19,628 amino acids (p.S19628IfsX1). No founder effect was found among the Israeli Arabs. In conclusion, titin is a giant protein with a key role in sarcomere assembly, force transmission, and maintenance of resting tension. Although some mutations result in skeletal myopathy, others cause isolated, maturity-onset cardiomyopathy.

Cardiac evaluation in children with Prader-Willi syndrome

AIM

To assess cardiac anatomy and myocardial systolic function in children with Prader-Willi syndrome (PWS).

METHODS

Physical examination, electrocardiographic (ECG) recordings and transthoracic echocardiograms including two-dimensional speckle tracking echocardiography (2DSTE) were performed and evaluated in the Radboud University Hospital Nijmegen, the Netherlands. In total, 19 children diagnosed with PWS and 38 age-matched control subjects underwent cardiac evaluation.

RESULTS

Abnormal ECG findings were detected in nine PWS patients. Echocardiography revealed mild structural cardiac abnormalities in two patients. Conventional echocardiographic findings did not indicate systolic left ventricular dysfunction, in contrast to 2DSTE examination. Global peak systolic strain (rate) measurements, in all three directions of contraction, were significantly lower in children with PWS (p < 0.001) compared with healthy age-matched children. In two-thirds of the patients, 2DSTE revealed abnormal systolic deformation (peak systolic strain as well as strain rate). T2P values in PWS patients were similar to control subject. Systolic myocardial function appears more affected in case of maternal uniparental disomy.

CONCLUSION

Cardiac evaluation, including 2DSTE, detects frequent alterations in myocardial systolic function in children diagnosed with PWS, whose conventional echocardiographic findings did not indicate ventricular systolic dysfunction. Because cardiovascular morbidity and mortality is substantial in PWS, especially adults, we emphasize the need for cardiac assessment in PWS.

Murine ultrasound imaging for circumferential strain analyses in the angiotensin II abdominal aortic aneurysm model

OBJECTIVE

The underlying causes of abdominal aortic aneurysms (AAAs) remain obscure, although research tools such as the angiotensin II (Ang II) apolipoprotein E-deficient (apoE(-/-)) mouse model have aided investigations. Longitudinal imaging and determination of biomechanical forces in this small-scale model have been difficult. We hypothesized that high-frequency ultrasound biomicroscopy combined with speckle-tracking analytical strategies can be used to define the role of circumferential mechanical strain in AAA formation in the Ang II/apoE(-/-) mouse model of AAAs. We simultaneously examined dietary perturbations that might impact the biomechanical properties of the aortic wall, hypothesizing that the generalized inflammatory phenotype associated with diet-induced obesity would be associated with accelerated loss of circumferential strain and aneurysmal aortic degeneration.

METHODS

Receiving either a 60 kcal% fat Western diet or standard 10 kcal% fat normal chow, Ang II-treated apoE(-/-) mice (n = 34) underwent sequential aortic duplex ultrasound scan imaging (Vevo 2100 System; VisualSonics, Toronto, Ontario, Canada) of their entire aorta. Circumferential strains were calculated using speckle-tracking algorithms and a custom MatLab analysis.

RESULTS

Decreased strains in all aortic locations after just 3 days of Ang II treatment were observed, and this effect progressed during the 4-week observation period. Anatomic segments along the aorta impacted wall strain (baseline highest in ascending aorta; P < .05), whereas diet did not. At 2 and 4 weeks, there was the largest progressive decrease in strain in the paravisceral/supraceliac aorta (P < .05), which was the segment most likely to be involved in aneurysm formation in this model.

CONCLUSIONS

In the Ang II/apoE(-/-) aneurysm model, the aorta significantly stiffens (with decreased strain) shortly after Ang II infusion, and this progressively continues through the next 4 weeks. High-fat feeding did not have an impact on wall strain. Delineation of biomechanical factors and AAA morphology via duplex scan and speckle-tracking algorithms in mouse models should accelerate insights into human AAAs.

Two-dimensional speckle-tracking echocardiography reveals systolic abnormalities in granulomatosis with polyangiitis (Wegener's)

BACKGROUND

Two-dimensional speckle-tracking echocardiography (STE) is a novel technique providing accurate assessment of myocardial function. However, its value in granulomatosis with polyangiitis (Wegener's) (WG) has not been studied.

OBJECTIVE

To assess the presence and frequency of systolic left ventricular (LV) dysfunction using STE and to determine incremental value of STE over standard echocardiography to detect myocardial abnormalities in WG.

METHODS

Twenty-two WG patients (11 males, 11 females, mean age 46.8 ± 12.3 years) and 22 sex- and age-matched healthy subjects underwent standard and STE. Global longitudinal, circumferential, and rotational deformation parameters were calculated.

RESULTS

All patients had LV ejection fraction (EF) >50%. LVEF was 65.0 ± 7.5% and LV end-diastolic volume index 44.8 ± 11.8 mL/m(2) . Regional LV wall motion abnormalities were found in 7 (32%), while abnormal global STE determined systolic dysfunction in 16 (73%) subjects (P = 0.008). Global longitudinal, circumferential and radial peak-systolic deformational parameters (strain or strain rate) were decreased in 11 (50%), 9 (41%), and 3 (14%) patients (P = 0.02), respectively. Comparing patients with abnormal and normal STE derived global systolic function, the former had higher cumulative disease extent index (10.6 ± 3.0 vs 7.5 ± 1.8; P = 0.03) and vasculitis damage index (7.9 ± 1.9 vs 6.0 ± 1.7; P = 0.04).

CONCLUSIONS

Despite normal LVEF the global systolic LV abnormalities detected by STE are common in WG. They correspond to the extent and severity of WG and are more frequent than regional wall motion abnormalities in standard echocardiography.

Persistent reduction in left ventricular strain using two-dimensional speckle-tracking echocardiography after balloon valvuloplasty in children with congenital valvular aortic stenosis

BACKGROUND

The aim of this study was to investige serial changes of myocardial deformation using two-dimensional speckle-tracking echocardiographic (2DSTE) imaging in children undergoing balloon valvuloplasty for congenital valvular aortic stenosis (VAS).

METHODS

Thirty-seven children with isolated congenital VAS were enrolled in this study prospectively. Patients underwent echocardiographic evaluation at three instances: before balloon valvuloplasty, 6 months after intervention, and 3 years after intervention. Longitudinal, circumferential, and radial peak systolic strain values were determined, as well as systolic strain rate and the time to peak global systolic strain. Linear mixed statistical models were used to assess changes in 2DSTE parameters after balloon intervention. Using one-way analysis of variance, 2DSTE results at 3-year follow-up were compared with 2DSTE measurements in 74 healthy age-matched children and 76 children with uncorrected VAS whose severity of stenosis corresponded to residual stenosis of study subjects at 3-year follow-up.

RESULTS

Global peak strain and strain rate measurements in all three directions were decreased before intervention compared with healthy children. Global peak strain and strain rate measurements increased significantly (P < .001) several months after balloon valvuloplasty and continued to increase at 3-year follow-up. However, at 3-year follow-up, global peak strain and strain rate in the longitudinal and circumferential directions were significantly lower (P < .001) compared with both control groups. Measurements of time to peak global systolic strain were significantly shorter at early follow-up compared with measurements before intervention (P < .05).

CONCLUSIONS

Shortly after balloon valvuloplasty for severe congenital VAS, there is an improvement in systolic myocardial deformation. However, 2DSTE parameters do not return to normal at 3-year follow-up. These abnormalities in systolic deformation cannot be fully attributed to residual stenosis or aortic regurgitation.

Assessment of subclinical left ventricular dysfunction in obstructive sleep apnea patients with speckle tracking echocardiography

In this study, our aim was to evaluate the LV (left ventricle) subclinical myocardial dysfunction using the two-dimensional speckle tracking echocardiography (2D-STE) method on obstructive sleep apnea (OSA) patients with preserved left ventricular ejection fraction (LVEF) and without any confounding disease that may result myocardial dysfunction. Twenty-one healthy individuals and 58 OSA patients were enrolled in the study. The patients were categorized into mild, moderate and severe OSA groups according to the apnea-hypopnea index (AHI). Conventional- and tissue Doppler echocardiography imagings were performed in all the individuals besides the 2D-STE. The longitudinal strain (S) and systolic strain rate (SR(S)) values decreased as the severity of disease increased from moderate towards severe OSA. The circumferential S and SR(S) values were observed to be lower in the severe OSA patients. Despite the increase in the radial S and SR(S) in moderate and mild OSA patients, these measurements decreased in those with severe OSA. Although the longitudinal, circumferential and radial early diastolic strain rates (SR(E)) decreased as the severity of disease increased form moderate to severe, the late diastolic strain rates (SR(A)) were observed to increase. In the early stages of OSA, longitudinal systolic LV dysfunction is detected in addition to the diastolic dysfunction. The circumferential mechanics of the LV deteriorate in the later stages of the OSA. Despite a compensatory increase in the radial LV function in the early stages of OSA, in later stages, the LV radial function also deteriorates. The assessment of the myocardial functions using the STE method in patients with OSA with preserved LVEF has the potential to detect the subclinical LV dysfunction and might provide useful information for risk stratification.

Echocardiographic assessment of myocardial strain

Echocardiographic strain imaging, also known as deformation imaging, has been developed as a means to objectively quantify regional myocardial function. First introduced as post-processing of tissue Doppler imaging velocity converted to strain and strain rate, strain imaging has more recently also been derived from digital speckle tracking analysis. Strain imaging has been used to gain greater understanding into the pathophysiology of cardiac ischemia and infarction, primary diseases of the myocardium, and the effects of valvular disease on myocardial function, and to advance our understanding of diastolic function. Strain imaging has also been used to quantify abnormalities in the timing of mechanical activation for heart failure patients undergoing cardiac resynchronization pacing therapy. Further advances, such as 3-dimensional speckle tracking strain imaging, have emerged to provide even greater insight. Strain imaging has become established as a robust research tool and has great potential to play many roles in routine clinical practice to advance the care of the cardiovascular patient. This perspective reviews the physiology of myocardial strain, the technical features of strain imaging using tissue Doppler imaging and speckle tracking, their strengths and weaknesses, and the state-of-the-art present and potential future clinical applications.

Comparison of the heart function adaptation in trained and sedentary men after 50 and before 35 years of age

The effects of aging and of sustained athletic activity on the heart in men aged >50 years are unknown. The aim of this study was to assess the adaptation of the heart in athletic and sedentary men aged <35 and ≥50 years. Echocardiograms recorded at rest and during submaximal exercise were analyzed in 59 athletic seniors (S(ATH) group) and 16 sedentary seniors (S(SED) group) (age ≥50 years) and in 18 athletic youth (Y(ATH) group) and 27 sedentary youth (Y(SED) group) (age <35 years). All subjects were healthy. The reproducibility of measurements was examined, and the echocardiographic characteristics were compared among the study groups. No differences were found in baseline characteristics between the Y(ATH) and Y(SED) groups and between the S(ATH) and S(SED) groups, except for their exercise routines, consisting of >8 hours of bicycling per week in the athletic groups. Left ventricular mass was greater in the Y(ATH) than in the S(ATH) group (p <0.01) and greater in the S(ATH) than in the S(SED) group (p <0.001). Likewise, left ventricular volumes were greater in the athletic than in the sedentary groups (p <0.05), although they were smaller in the seniors than in youth (p <0.01). Left ventricular stroke volume was greater in the athletic than in the sedentary groups (p <0.001); global longitudinal strain during exercise was -20.0 ± 2.4% in the S(ATH) group and -22.1 ± 2.1% in the Y(ATH) group, compared to -19.2 ± 3.4% in the S(SED) group and -20.2 ± 2.4% in the Y(SED) group (p <0.05, athletic vs sedentary). The e' velocities recorded at the septal and lateral mitral annulus were higher at rest and during exercise (p <0.01) in the youth than in the senior groups. In conclusion, systolic and diastolic myocardial adaptation to regular exercise was significantly more prominent in young than in senior volunteers.

Severity of mitral stenosis and left ventricular mechanics: a speckle tracking study

BACKGROUND

It has been shown that mitral stenosis (MS) impairs left ventricular (LV) systolic function; however, this issue has not been studied comprehensively. We aimed to evaluate the role of 2D strain in the assessment of subclinical LV systolic dysfunction in patients with MS.

METHODS

Seventy-two patients with isolated MS (mild, moderate and severe) and 31 healthy control subjects constituted the study population. 2D echocardiography images were obtained from LV apical 4-chamber (4C), long axis (LAX), and 2-chamber (2C) views. Peak longitudinal strain and strain rate (Sr) were obtained from 4C, LAX, and 2C views. Global strain and Sr were calculated by averaging the three apical views.

RESULTS

There were no significant differences in LV ejection fraction and LV systolic or diastolic dimensions between the groups. Patients with MS had significantly lower LV longitudinal strain and Sr measurements than the control group. In addition, there were no significant differences in MS subgroups with respect to LV strain and Sr measurements.

CONCLUSION

We demonstrated that patients with MS had lower LV functions using 2D strain imaging, and this is independent of the hemodynamic severity of MS. In the detection of subclinical LV dysfunction in patients with MS, 2D strain imaging appears to be useful.

Color-coded longitudinal interventricular septal tissue velocity imaging, strain and strain rate in healthy Doberman Pinschers

OBJECTIVE

To determine reference values for septal longitudinal tissue Doppler imaging (TDI) in Doberman Pinschers.

BACKGROUND

TDI includes several new techniques, such as tissue velocity imaging (TVI), strain, and strain rate that might be used to detect early myocardial dysfunction. However, before these techniques can be used, breed specific reference ranges need to be established.

ANIMALS, MATERIALS AND METHODS

One-hundred healthy Doberman Pinschers ≥ 4 years of age were prospectively evaluated using electrocardiography, Holter recording, and echocardiography. Systolic, early and late diastolic parameters of septal longitudinal color-coded TVI, strain, and strain rate were analyzed in three myocardial segments (basal, middle, and apical).

RESULTS

TDI was feasible in all Doberman Pinschers. Reference values were established for every myocardial segment. There was a significant velocity gradient from the basal to the apical segment for all TVI parameters. No differences between the three segments were found for systolic strain and strain rate. Several diastolic strain rate values were significantly different between myocardial segments. Influence of age, weight, and gender was not clinically relevant.

CONCLUSIONS

This study provides reference values for TVI, strain, and strain rate in Doberman Pinschers. The parameters established here can be used for a supportive diagnostic approach.

Detection of preclinical impairment of myocardial function in rheumatoid arthritis patients with short disease duration by speckle tracking echocardiography

BACKGROUND

Subclinical cardiac involvement diagnosis is important for long term management of rheumatoid arthritis (RA) patients. Recently, 2D speckle tracking echocardiography (STE) allows non invasive and angle-independent measurement of left ventricular (LV) dimensions and regional myocardial strain (ε). The aim of this study was to assess whether STE can be useful to detect subclinical cardiac involvement in RA patients.

METHODS

We studied 22 RA patients (10 M, 12 F, aged 46 ± 12 years) without clinical evidence of coronary artery disease (CAD) and 20 healthy controls matched for age and sex by STE. LV end-systolic longitudinal and radial ε from apical 4-chamber view were analyzed using available software (QLAB 6.0).

RESULTS

Standard echo and Doppler parameters did not differ between the 2 groups. Tissue Doppler Imaging (TDI) showed a significant reduction of S', E' and E'/A' ratio from the basal septum and lateral mitral annulus in RA patients. LV end-systolic radial and longitudinal ε of basal-lateral, basal- and mid-septal, mid-lateral and apical segments were significantly reduced compared to controls.

CONCLUSIONS

Our data indicate that LV end-systolic radial and longitudinal ε are reduced in RA patients without CAD despite normal standard echo. Non invasive evaluation of LV function by STE appears to be useful to detect subclinical cardiac involvement in comparison to conventional 2D echoDoppler, representing a promising new modality to follow-up RA patients for cardiac involvement.

Two-dimensional strain combined with adenosine stress echocardiography assessment of viable myocardium

The objective of this study was to explore a new method for the identification of viable myocardium by means of two-dimensional (2D) strain imaging combined with adenosine stress echocardiography. A total of 15 anesthetized open-chest healthy mongrel dogs underwent left anterior descending coronary artery occlusion for 90 min followed by 120-min reperfusion. Adenosine was infused at 140 μg kg(-1) min(-1) over a period of 6 min. Images were acquired at baseline (when pericardial cradle was made), after reperfusion (when reperfusion finished) and after adenosine administration (while administration stopped). Measurements of the regional peak-systolic strain in radial, circumferential, and longitudinal motion on anterior wall and anterior septum were, respectively, performed under different conditions. The dogs were killed after the echocardiographic studies finished and then the area of infracted myocardium was defined by triphenyltetrazolium chloride histology. A segment with equal or less than 50% area of infracted myocardium was considered to be viable. As a result, 37 regions were viable whereas 53 were non-viable among 90 regions in 15 dogs. At baseline, there was no significant difference in peak-systolic radial strain (Rs), circumferential strain (Cs), and longitudinal strain (Ls) between the viable and non-viable groups. After reperfusion, Rs, Cs, and Ls in absolute value decreased compared to those at baseline in both groups, although there was no significant difference between these groups. Rs and Ls increased after adenosine administration compared to reperfusion (p < 0.01; p < 0.05) in viable group while there were no changes in non-viable group. Compared with non-viable group Rs, Cs and Ls in viable group increased significantly (p < 0.01; 0.05) after adenosine administration. There was a negative correlation between Rs and infarct size (r = -0.72). Cs and Ls correlated well with infarct size, respectively (r = 0.40; 0.67). A change of Rs more than 13.5% has a sensitivity of 83.8% and a specificity of 83.0% for viable whereas a change of Ls more than 11% allowed a sensitivity of 78.4% and a specificity of 88.7%. Combined with these two variables, the sensitivity and specificity could reach 91.9 and 79.2%. Two-dimensional strain imaging combined with adenosine stress echocardiography can provide a new way to distinguish viable myocardium from the non-viable.

Cellular and Functional Imaging of Cardiac Transplant Rejection

Heart transplantation is now an established treatment for patients suffering from end-stage heart diseases. With the advances in immunosuppressive treatment, the survival rate for transplant patients has improved greatly. However, allograft rejection, both acute and chronic, after heart transplantation is still a limitation leading to morbidity and mortality. The current clinical gold standard for screening rejection is endomyocardial biopsy (EMB), which is not only invasive, but also error-prone, due to the limited sample size and the site location of sampling. It would be highly desirable to have reliable and noninvasive alternatives for EMB in monitoring cardiac allograft rejection. The objective of this review is to highlight how cardiovascular imaging can contribute to noninvasively detecting and to evaluating both acute and chronic allograft rejection after heart transplantation, in particular, cardiovascular MRI (CMRI); and how CMRI can assess both immune cell infiltration at the rejecting organ, and the cardiac dysfunctions resulting from allograft rejection.

Heart failure reversal by ventricular unloading in patients with chronic cardiomyopathy: criteria for weaning from ventricular assist devices

Aims

Unloading-promoted reversal of heart failure (HF) allows long-term transplant-free outcome after ventricular assist device (VAD) removal. However, because few patients with chronic cardiomyopathy (CCM) were weaned from VADs (the majority only recently), the reliability of criteria used for weaning decisions to predict long-term post-weaning success is barely known. After 15 years of weaning experience, we assessed this issue.

Methods and results

In 47 patients with CCM as the underlying cause for HF, who were part of a total of 90 patients weaned from bridge-to-transplant-designed VADs since 1995, we analysed data on cardiac morphology and function collected before VAD implantation, echocardiographic parameters recorded during ‘off-pump’ trials, duration of HF before implantation, and stability of recovery before and early after VAD removal. Post-weaning 5 year freedom from HF recurrence reached 66%. Only five patients (10.6%) died due to HF recurrence or weaning-related complications. Pre-explantation off-pump left ventricular ejection fraction (LVEF) of ≥50 and ≥45% revealed predictive values for cardiac stability lasting ≥5 years after VAD removal of 91.7 and 79.1%, respectively. With each unit of LVEF reduction, the risk of HF recurrence became 1.5 times higher. The predictive value of LVEF ≥45% also became >90% if additional parameters like pre-explantation LV size and geometry, stability of unloading-induced cardiac improvement before VAD removal, and HF duration before VAD implantation were also considered. Definite cut-off values for certain parameters (including tissue-Doppler-derived LV wall motion velocity) allowed formulation of weaning criteria with high predictability for post-weaning stability, also in patients with incomplete cardiac recovery.

Conclusions

Ventricular assist device removal in CCM patients is feasible and can be successful even after incomplete cardiac recovery. Parameters of pre-explantation cardiac function, LV size and geometry, their stability during final off-pump trials, and HF duration allow detection of patients with the potential to remain stable for >5 post-weaning years.

Role of cardiovascular imaging in systemic autoimmune diseases

Systemic autoimmune diseases are characterized by an excess of cardiovascular (CV) morbidity and mortality compared to the general population, mainly due to chronic inflammation that promotes the development of endothelial dysfunction and enhanced atherosclerosis. Early diagnosis of silent CV involvement is mandatory to improve the long term prognosis of these patients and CV imaging provides valuable information as a reliable diagnostic tool. Transthoracic echocardiography, with several applications (e.g. coronary flow reserve evaluation, tissue Doppler imaging, speckle tracking and the transesophageal approach), represents a first line evaluation, in association with biomarkers of endothelial dysfunction, such as asymmetric dimethylarginine. Nuclear medicine provides useful information on myocardial perfusion. The aim of this editorial is to provide a brief but complete review of the diagnostic tools available for screening and follow up of CV involvement in systemic autoimmune diseases.

Analyses of left ventricular myocardial deformation by speckle-tracking imaging during the acute phase of Kawasaki disease

This study aimed to investigate left ventricular myocardial deformation in children with Kawasaki disease during the acute phase of their illness. A total of 50 patients and 35 normal control subjects were assessed. Data were obtained from the patients during the acute and convalescent phases of Kawasaki disease. Analyses of myocardial deformation [strain (epsilon), strain rate (SR)] was performed using two-dimensional speckle-tracking imaging in three directions (longitudinal, circumferential, and radial) at the basal and mid levels of the left ventricular myocardium. Basal longitudinal epsilon (P < 0.001) and midlongitudinal epsilon (P < 0.0001) were lower during the acute phase of the disease than in the control subjects and associated with serum albumin level and left ventricular mass index (LVMI). Midlongitudinal SR (P < 0.0001) was lower during the acute phase of Kawasaki disease than in the control subjects and associated with LVMI. Decreased systolic SR was not detected in any direction. In conclusion, left ventricular longitudinal systolic epsilon was significantly decreased during the acute phase of Kawasaki disease. This may be a result of myocardial swelling from myocarditis during the acute phase of the disease.

Speckle tracking imaging improves in vivo assessment of EPO-induced myocardial salvage early after ischemia-reperfusion in rats

A noninvasive assessment of infarct size and transmural extension of myocardial infarction (TEMI) is fundamental in experimental models of ischemia-reperfusion. Conventional echocardiography parameters are limited in this purpose. This study was designed to examine whether speckle tracking imaging can be used in a rat model of ischemia-reperfusion to accurately detect the reduction of infarct size and TEMI induced by erythropoietin (EPO) as early as 24 h after reperfusion. Rats were randomly assigned to one of three groups: myocardial infarction (MI)-control group, 45 min ischemia followed by 24 h of reperfusion; MI-EPO group, similar surgery with a single bolus of EPO administered at the onset of reperfusion; and sham-operated group. Short-axis two-dimensional echocardiography was performed after reperfusion. Global radial (GSr) and circumferential (GScir) strains were compared with infarct size and TEMI assessed after triphenyltetrazolium chloride staining. As a result, ejection fraction, shortening fraction, GSr, and GScir significantly correlated to infarct size, whereas only GSr and GScir significantly correlated to TEMI. EPO significantly decreased infarct size (30.8 ± 3.5 vs. 56.2 ± 5.7% in MI-control, P < 0.001) and TEMI (0.37 ± 0.05 vs. 0.77 ± 0.05 in MI-control, P < 0.001). None of the conventional echocardiography parameters was significantly different between the MI-EPO and MI-control groups, whereas GSr was significantly higher in the MI-EPO group (29.1 ± 4.7 vs. 16.4 ± 3.3% in MI-control; P < 0.05). Furthermore, GScir and GSr appeared to be the best parameters to identify a TEMI >0.75 24 h after reperfusion. In conclusion, these findings demonstrate the usefulness of speckle tracking imaging in the early evaluation of a cardioprotective strategy in a rat model of ischemia-reperfusion.

Speckle-tracking 2-dimensional strain echocardiography: a new noninvasive imaging tool to evaluate acute rejection in cardiac transplantation

BACKGROUND

There remains no reliable non-invasive method to detect cardiac transplant rejection. Recently, speckle-tracking 2-dimensional strain echocardiography (2DSE) was shown to be sensitive in the early detection of myocardial dysfunction in various models of cardiomyopathy. We aim to determine if 2DSE-derived functional indices can detect cardiac transplant rejection.

METHODS

Heterotopic rat cardiac transplantation was performed in histocompatible isografts or histoincompatible allografts. Histologic rejection scores were determined. Short-axis, mid-left ventricular (LV) echocardiography was performed on Day 6 after transplantation. Conventional measures of function were measured, (including LV fractional shortening and ejection fraction) as well as 2DSE parameters.

RESULTS

Despite class IIIB rejection in allografts and no rejection in isografts, there was no difference between isografts vs allografts in fractional shortening (15% +/- 3% vs 12% +/- 3%) or ejection fraction (36% +/- 5% vs 26% +/- 6%; both not significant). In contrast, 2DSE revealed decreases between isografts and allografts in global radial strain (12.6% +/- 5.6% vs 1.1% +/- 0.2%, p < 0.05), peak radial systolic strain rate (3.10 +/- 0.74/s vs 0.54 +/- 0.13/s, p < 0.001), and peak circumferential systolic strain rate (-1.99 +/- 0.55 vs -0.43 +/- 0.11/s; p < 0.01).

CONCLUSIONS

Systolic strain imaging using 2DSE differentiates myocardial function between experimental cardiac transplant rejection in allografts and non-rejection in isografts. Therefore, 2DSE may be useful in early non-invasive detection of transplant rejection.

3-D phantom and in vivo cardiac speckle tracking using a matrix array and raw echo data

Cardiac motion has been tracked using various methods, which vary in their invasiveness and dimensionality. One such noninvasive modality for cardiac motion tracking is ultrasound. Three-dimensional ultrasound motion tracking has been demonstrated using detected data at low volume rates. However, the effects of volume rate, kernel size, and data type (raw and detected) have not been sufficiently explored. First comparisons are made within the stated variables for 3-D speckle tracking. Volumetric data were obtained in a raw, baseband format using a matrix array attached to a high parallel receive beam count scanner. The scanner was used to acquire phantom and human in vivo cardiac volumetric data at 1000-Hz volume rates. Motion was tracked using phase-sensitive normalized cross-correlation. Subsample estimation in the lateral and elevational dimensions used the grid-slopes algorithm. The effects of frame rate, kernel size, and data type on 3-D tracking are shown. In general, the results show improvement of motion estimates at volume rates up to 200 Hz, above which they become stable. However, peak and pixel hopping continue to decrease at volume rates higher than 200 Hz. The tracking method and data show, qualitatively, good temporal and spatial stability (for independent kernels) at high volume rates.

Speckle tracking echocardiography: A new approach to myocardial function

Echocardiography is the most common diagnostic method for assessing cardiac function but some limitations affect this technique. Until now, visual assessment of wall motion and thickening has allowed only a subjective evaluation of myocardial function and requires long-term training. Recently, new echocardiographic techniques have been introduced to evaluate myocardial mechanics. Tissue Doppler imaging (TDI) technique is limited by angle-dependency such that only deformation along the ultrasound beam can be derived from velocities, while myocardium deforms simultaneously in three dimensions. Speckle tracking echocardiography (STE) is a more recent technique that provides a global approach to left ventricular myocardial mechanics, giving information about the three spatial dimensions of cardiac deformation. In this editorial, we describe the physical and pathophysiological concepts of STE, discussing the differences compared to TDI and underlining the pitfalls of this new technique.

Validation of echocardiographic two-dimensional speckle tracking longitudinal strain imaging for viability assessment in patients with chronic ischemic left ventricular dysfunction and comparison with contrast-enhanced magnetic resonance imaging

The purpose of the present study was to compare longitudinal strain assessed by two-dimensional speckle tracking with scar tissue on contrast-enhanced magnetic resonance imaging (MRI) in patients with chronic ischemic left ventricular (LV) dysfunction. The aim was also to define a cutoff value for regional strain to discriminate between viable myocardium and transmural scar. Ninety patients with chronic ischemic LV dysfunction underwent transthoracic echocardiography to measure global and segmental (regional) longitudinal LV strain using two-dimensional speckle tracking and cine MRI followed by contrast-enhanced MRI to assess segmental LV function and the segmental/global (transmural) extent of scar tissue. The optimal cutoff value for regional strain to discriminate between segments with viable myocardium and segments with transmural scar was also determined. A good correlation was found between global LV strain and the global extent of scar tissue on contrast-enhanced MRI (R = 0.62, p <0.001). The mean segmental strain in segments without scar tissue was -10.4% +/- 5.2% compared with 0.6% +/- 4.9% in segments with transmural scar tissue (p <0.001). A strain value of -4.5% discriminated between segments with viable myocardium and segments with transmural scar tissue on contrast-enhanced MRI with a sensitivity of 81.2% and specificity of 81.6%. In conclusion, global and regional longitudinal strain measured with two-dimensional speckle tracking is associated with the global and regional (transmural) extent of scar tissue on contrast-enhanced MRI. A cutoff value of -4.5% for regional strain discriminated between segments with viable myocardium and those with transmural scar tissue on contrast-enhanced MRI with a sensitivity of 81.2% and specificity of 81.6%.

Recent advances in the application of computational mechanics to the diagnosis and treatment of cardiovascular disease

During the last 30 years, research into the pathogenesis and progression of cardiovascular disease has had to employ a multidisciplinary approach involving a wide range of subject areas, from molecular and cell biology to computational mechanics and experimental solid and fluid mechanics. In general, research was driven by the need to provide answers to questions of critical importance for disease management. Ongoing improvements in the spatial resolution of medical imaging equipment coupled to an exponential growth in the capacity, flexibility and speed of computational techniques have provided a valuable opportunity for numerical simulations and complex experimental techniques to make a contribution to improving the diagnosis and clinical management of many forms of cardiovascular disease. This paper contains a review of recent progress in the numerical simulation of cardiovascular mechanics, focusing on three particular areas: patient-specific modeling and the optimization of surgery in pediatric cardiology, evaluating the risk of rupture in aortic aneurysms, and noninvasive characterization of intraventricular flow in the management of heart failure.

2-Dimensional strain echocardiography and early detection of myocardial ischemia

Echocardiographic strain with strain rate imaging is a new technology enabling more reliable and comprehensive assessment of myocardial function. The spectrum of potential clinical applications is very wide due to its ability to differentiate between active and passive movement of myocardial segments, to quantify intraventricular dyssynchrony and to evaluate components of myocardial function, such as longitudinal myocardial shortening, that are not visually assessable. In-vivo and in-vitro validation of 2D-strain imaging technique have been undertaken and reached a point where it is considered ready for more widespread investigations into clinical utility, e.g. regarding myocarditis, arrhythmogenic right ventricular dysplasia/cardiomyopathy and regional ischemia. Moreover, longitudinal LV strain is closely related to log plasma brain-type natriuretic peptide levels in patients with congestive heart failure, both in patients with systolic and diastolic heart failure. We present a case of detection of coronary artery disease in a 55-year-old Italian man. This case focuses attention on the higher sensibility of the 2-Dimensional Strain echocardiography the diagnosis of myocardial ischemia in patients with coronary artery disease.