Tissue Doppler and strain imaging: anything left in the echo-lab?

Development of tissue Doppler-derived predictors of hemodynamically significant patent ductus arteriosus and the ability to incorporate it in targeted neonatal echocardiography protocol

Background

Hemodynamically significant (HS) patent ductus arteriosus (PDA) is a significant cause of mortality in preterm neonates. Early detection of HS PDA and pre-symptomatic closure may help in avoiding complications. For this to happen, easily performed predictors must be available; the aim of this paper is to test the reliability and repeatability of tissue Doppler-derived parameters for prediction of HS PDA.

Methods

Preterm neonates <32 weeks were screened with echocardiography at Day 3 of life; 80 neonates with PDA were classified into HS group and hemodynamically insignificant (HIS) group based on benchmark parameter namely left ventricular outflow to superior vena caval flow ratio (LVO/SVC), and a ratio ≥4 was considered predictive of HS PDA. Tissue Doppler-derived left ventricular myocardial systolic and diastolic velocities were also performed.

Results

In total, 105 neonates (55 among HS and 60 among HIS groups) were included in the study. Septal systolic velocity (S′) proved of high sensitivity (100%) in the prediction of HS PDA; nevertheless, it proved to be more repeatable than the initially discriminating parameter (LVO/SVC) with a Kappa of 0.92.

Conclusion

This study concludes that septal S′ can be reliably used even by neonatologists for pre-symptomatic detection of HS PDA. This may also indicate the need of adding tissue Doppler parameters to the standard protocol of targeted neonatal echocardiography.

An Optical Method for the In-Vivo Characterization of the Biomechanical Response of the Right Ventricle

The intraoperative in-vivo mechanical function of the left ventricle has been studied thoroughly using echocardiography in the past. However, due to technical and anatomical issues, the ultrasound technology cannot easily be focused on the right side of the heart during open-heart surgery, and the function of the right ventricle during the intervention remains largely unexplored. We used optical imaging and digital image correlation for the characterization of the right ventricle motion and deformation during open-heart surgery. This work is a pilot study focusing on one patient only with the aim of establishing the framework for long term research. These experiments show that optical imaging and the analysis of the images can be used to obtain similar parameters, and partly at higher accuracy, for describing the mechanical functioning of the heart as the ultrasound technology. This work describes the optical imaging based method to characterize the mechanical response of the heart in-vivo, and offers new insight into the mechanical function of the right ventricle.

Effect of food intake on left and right ventricular systolic tissue Doppler measurements

Systolic tissue Doppler measurements (s') have been used to measure the velocity in myocardial motion and are a valuable tool for evaluating the systolic function of the left and right ventricles. Digestion of food is known to significantly alter hemodynamics and may therefore affect s'. The effect of food intake on s' parameters has not yet been studied. We assessed whether s' is affected by food intake. Nineteen healthy subjects aged 26·2 ± 4·2 years were investigated. s' was measured with pulsed tissue Doppler imaging in the right and left ventricles before the subjects ate a standardized meal and also 30 and 110 min after the meal. Three measurements were taken in each projection, and a mean value was calculated for each. s' increased significantly (P<0·05) from fasting to 30 min after food intake in every measured site except in the left inferolateral wall (P = 0·15, NS). Several, but not all, variables returned to base value 110 min after food intake. This study shows that food intake affects the tissue Doppler variables used to evaluate systolic heart function. Further studies are needed in older healthy subjects and older subjects with various cardiovascular diseases.

Speckle-tracking and tissue-Doppler stress echocardiography in arterial hypertension: a sensitive tool for detection of subclinical LV impairment

Early diagnosis of cardiac alterations in hypertensive heart disease is still challenging. Since such patients might have depressed global LV systolic strain or strain rate when EF is still normal, speckle-tracking echocardiography (STE) and tissue-Doppler imaging (TDI) combined with stress echocardiography might improve early diagnosis of cardiac alterations. In this prospective study standard 2D Doppler echocardiography, STE, and TDI were performed at rest and during bicycle exercise in 92 consecutive patients—46 hypertensive subjects with normal ejection fraction and 46 healthy controls. STE and TDI were used to measure global peak systolic LV circumferential strain (CS), longitudinal strain (LS), and longitudinal strain rate (SR). Mean arterial blood pressure was significantly higher in hypertensive patients at rest (100.8 mmHg SD 13.5 mmHg; P = 0.002) and during physical exercise testing (124.2 mmHg SD 13.4 mmHg; P = 0.003). Hypertensive patients had significantly reduced values of systolic CS (P = 0.001), LS (P = 0.014), and SR (P < 0.001) at rest as well as during physical exercise—CS (P < 0.001), LS (P < 0.001), and SR (P < 0.001). Using STE and TDI, reduced LV systolic strain and strain rate consistent with early cardiac alterations can be detected in patients with arterial hypertension. These findings were evident at rest and markedly pronounced during exercise echocardiography.

Evaluation of traditional and novel measures of cardiac function to detect anthracycline-induced cardiotoxicity in survivors of childhood cancer

PURPOSE

Cardiovascular disease is the leading noncancer cause of death among survivors of childhood cancer. Ejection fraction (EF) and fractional shortening (FS) are common echocardiographic measures of cardiac function, but newer imaging modalities may provide additional information about preclinical disease. This study aimed to evaluate these modalities in detection of anthracycline-induced cardiac toxicity.

METHODS

We compared mean radial displacement, EF, and FS among 17 adult survivors of childhood cancer exposed to ≥ 300 mg/m(2) of anthracyclines to 17 age- and sex-matched healthy controls. Survivors with a history of cardiac-directed radiation, diabetes, or heart disease were excluded.

RESULTS

Survivors (35% male), mostly with history of treatment for a solid tumor, had a median age at diagnosis of 15 years (1-20) and 27 years (18-50) at evaluation. Median anthracycline exposure was 440 (range 300-645) mg/m(2). FS (35.5 vs. 39.6%, p < 0.01) and radial displacement (5.6 vs. 6.7 mm, p = 0.02) were significantly lower in survivors compared to controls, respectively. Although the mean EF was lower in survivors versus controls (55.4 vs. 59.7%), it was not statistically significant (p = 0.057). All echocardiographic measures were inversely associated with anthracycline dose, though radial displacement was no longer significantly correlated with anthracycline dose after controlling for survival time (p = 0.07), while EF remained correlated (p = 0.003).

IMPLICATIONS FOR CANCER SURVIVORS

Radial displacement, EF, and FS are lower in childhood cancer survivors compared to controls. In this study, radial displacement added no new information beyond the traditional measures, but clinical utility remains undetermined and requires further longitudinal study.

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.

Acute and chronic effects of smoking on myocardial function in healthy heavy smokers: a study of Doppler flow, Doppler tissue velocity, and two-dimensional speckle tracking echocardiography

BACKGROUND

The purpose of the study was to evaluate the acute and chronic effect of smoking on left ventricular function in healthy heavy smokers by conventional Doppler flow, tissue Doppler, and two-dimensional speckle tracking echocardiography (2D-STE).

METHODS

Echocardiograms were performed in 42 healthy heavy (>20 cigarettes/day) smokers (age 34 ± 5 years), before (group SM-1), 15 minutes (SM-2) and 30 minutes (SM-3) after starting smoking 2 cigarettes. Nonsmokers (n = 41, age 33 ± 4 years) served as controls. Transmitral flow, isovolumetric relaxation time (IVRT), and myocardial performance index (MPI) were measured. Tissue velocity measurements were averaged from lateral and septal mitral annulus. Longitudinal strain (GS), systolic (SRs), early diastolic (SRe), late diastolic (SRa), and isovolumetric relaxation (SRivr) strain rate were measured. The percent change in strain from end-systole to the first one-third of diastole (SI-DI = [(GS - strain at one-third diastole)/GS] × 100) was also measured.

RESULTS

IVRT and MPI were increased and early diastolic mitral annular velocity was decreased in SM-2; they returned to baseline in SM-3. There was no difference in GS and SRs. SRe and SRivr were reduced in SM-1 (P < 0.05), and remained significantly reduced in SM-2 and SM-3. SI-DI was lower in SM-1 (P = 0.011) and was further reduced in SM-2 and SM-3 (P < 0.001).

CONCLUSION

Acute and chronic smoking inhalation has adverse effects on myocardial function in healthy heavy smokers. 2D-STE is able to detect both baseline differences and late acute effects of smoking.

Echocardiography in pulmonary arterial hypertension: from diagnosis to prognosis

Pulmonary arterial hypertension is most often diagnosed in its advanced stages because of the nonspecific nature of early symptoms and signs. Although clinical assessment is essential when evaluating patients with suspected pulmonary arterial hypertension, echocardiography is a key screening tool in the diagnostic algorithm. It provides an estimate of pulmonary artery pressure, either at rest or during exercise, and is useful in ruling out secondary causes of pulmonary hypertension. In addition, echocardiography is valuable in assessing prognosis and treatment options, monitoring the efficacy of specific therapeutic interventions, and detecting the preclinical stages of disease.

Cardiac abnormalities in severe acute dichlorvos poisoning

OBJECTIVE

Patients with organophosphorus poisoning sometimes die suddenly during rigorous treatment, possibly from myocardial injury. This study sought to elucidate the mechanisms underlying organophosphorus poisoning-induced cardiotoxicity.

DESIGN

Prospective observational study.

SETTING

Urban, tertiary teaching hospital emergency intensive care unit with 10 beds.

PATIENTS

Forty-one patients with severe acute dichlorvos poisoning were consecutively enrolled (n = 92) at emergency intensive care unit and followed for 3 months.

MEASUREMENTS AND MAIN RESULTS

Levels of serum creatine kinase isoenzyme myocardium, cardiac troponin I, acetylcholinesterase, acetylcholine, epinephrine, and norepinephrine were tested on hospital days 1, 3, and 5 and on discharge day. Electrocardiography was recorded on admission and then every other day. Transthoracic echocardiography was performed at admission, in the acute phase, before discharge, and during follow-up. Technetium 99m-sestamibi myocardial single photon emission computed tomography was conducted in four patients. Thirty-seven (90.2%) patients survived and four (9.8%) patients died during treatment. We observed sinus tachycardia in 37 (90.2%) patients and ST-T changes in 33 (80.4%) patients. Creatine kinase isoenzyme myocardium and cardiac troponin I levels peaked at day 3 postadmission and then decreased to normal levels. Serum acetylcholine, epinephrine, and norepinephrine peaked at day 1 after admission and then decreased. Echocardiography revealed marked decreases in wall motion of the interventricular septum and left ventricle in the acute phase but returned to normal in the recovery phase. The left ventricular ejection fraction improved significantly from 42 ± 5% to 59 ± 4% (p = .001). Single photon emission computed tomography showed abnormal left ventricle perfusion.

CONCLUSION

Severe acute dichlorvos poisoning is associated with reversible myocardial dysfunction, possibly through an increase in catecholamine levels.

Cardiac tissue Doppler and tissue velocity imaging in anesthetized New Zealand white rabbits

New Zealand white rabbits are commonly used in cardiovascular research. Complete echocardiographic examination of the heart includes the evaluation of tissue Doppler (TDI) parameters, yet normal data are unavailable for rabbits. In addition, tissue velocity imaging (TV) is a potentially useful measure of myocardial function that has not yet been applied to rabbits. Anesthetized New Zealand white rabbits (n = 31) underwent echocardiography to establish the feasibility of performing TDI and TV and establishing corresponding reference values. Standard 2D, M-mode, and Doppler measurements were obtained in all rabbits and showed values comparable to previously published data. Interpretable TDI images were obtained in all 31 rabbits and TV in 24 of 31 rabbits. The values obtained were similar to those seen in healthy cats and are comparable to the values found in adult humans. TDI and TV can easily be added to standard echocardiographic evaluation in rabbits. The values from the current study, obtained in normal rabbits, can be used as reference values to improve characterization of cardiac disease in this species.

Relationship between postprandial changes in cardiac left ventricular function, glucose and insulin concentrations, gastric emptying, and satiety in healthy subjects

Background

The digestion of food is known to alter the hemodynamics of the body significantly. The purpose of this study was to study the postprandial changes in stroke volume (SV), cardiac output (CO) and left ventricular (LV) longitudinal systolic and diastolic functions measured with tissue Doppler imaging, in relation to gastric emptying rate (GER), satiety, and glucose and insulin concentrations in healthy subjects.

Methods

Twenty-three healthy subjects were included in this study. The fasting and postprandial changes at 30 min and 110 min in CO, heart rate (HR) and blood pressure were measured. Moreover, tissue Doppler imaging systolic (S'), early (E') and late (A') mitral annular diastolic velocities were measured in the septal (s) and lateral (l) walls. Glucose and insulin concentrations, and satiety were measured before and 15, 30, 45, 60, 90, and 120 min after the start of the meal. The GER was calculated as the percentage change in the antral cross-sectional area 15-90 min after ingestion of the meal.

Results

This study show that both CO, systolic longitudinal ventricular velocity of the septum (S's) and lateral wall (S'l), the early diastolic longitudinal ventricular velocity of the lateral wall (E'l), the late diastolic longitudinal ventricular velocity of the septum (A's) and lateral wall (A'l) increase significantly, and were concomitant with increased satiety, antral area, glucose and insulin levels. The CO, HR and SV at 30 min were significantly higher, and the diastolic blood pressure was significantly lower, than the fasting. The satiety was correlated to HR and diastolic blood pressure. The insulin level was correlated to HR.

Conclusions

This study shows that postprandial CO, HR, SV and LV longitudinal systolic and diastolic functions increase concomitantly with increased satiety, antral area, and glucose and insulin levels. Therefore, patients should not eat prior to, or during, cardiac evaluation as the effects of a meal may affect the results and their interpretation.

Trial Registration

ClinicalTrials.gov: NCT01027507

Left ventricular strain and strain rate by 2D speckle tracking in chronic thromboembolic pulmonary hypertension before and after pulmonary thromboendarterectomy

BACKGROUND

Echocardiographic evaluation of left ventricular (LV) strain and strain rate (SR) by 2D speckle tracking may be useful tools to assess chronic thromboembolic pulmonary hypertension (CTEPH) severity as well as response to successful pulmonary thromboendarterectomy (PTE).

METHODS

We evaluated 30 patients with CTEPH before and after PTE using 2D speckle tracking measurements of LV radial and circumferential strain and SR in the short axis, and correlated the data with right heart catheterization (RHC).

RESULTS

PTE resulted in a decrease in mean PA pressure (44 ± 15 to 29 ± 9 mmHg), decrease in PVR (950 ± 550 to 31 ± 160 [dyne-sec]/cm⁵), and an increase in cardiac output (3.9 ± 1.0 to 5.0 ± 1.0 L/min, p < 0.001 for all). Circumferential and posterior wall radial strain changed by -11% and +15% respectively (p < 0.001 for both). Circumferential SR and posterior wall radial SR changed by -7% and 6% after PTE. While the increase in posterior wall SR with PTE reached statistical significance (p = 0.04) circumferential SR did not (p = 0.07). In addition, septal radial strain and SR did not change significantly after PTE (p = 0.1 and 0.8 respectively). Linear regression analyses of circumferential and posterior wall radial strain and SR revealed little correlation between strain/SR measurements and PVR, mean PA pressure, or cardiac output. However, change in circumferential strain and change in posterior wall radial strain correlated moderately well with changes in PVR, mean PA pressure and cardiac output (r = 0.69, 0.76, and 0.51 for circumferential strain [p < 0.001 for all] and r = 0.7, 0.7, 0.45 for posterior wall radial strain [p = 0.001, 0.001, and 0.02, respectively]).

CONCLUSIONS

LV circumferential and posterior wall radial strain change after relief of pulmonary arterial obstruction in patients with CTEPH, and these improvements occur rapidly. These changes in LV strain may reflect effects from improved LV diastolic filling, and may be useful non-invasive markers of successful PTE.

Non-uniform recovery of left ventricular transmural mechanics in ST-segment elevation myocardial infarction

BACKGROUND

After a transient ischemic episode, the subendocardial region is more severely injured than outer subepicardial layers and may regain a proportionately greater degree of mechanical function in the longitudinal direction. We sought to explore left ventricular (LV) transmural mechanics in patients with ST-segment elevation myocardial infarction (STEMI) for determining the mechanism underlying recovery of global LV function after primary percutaneous coronary intervention (PCI).

METHODS

A total of 42 patients (62 +/- 11 years old, 71% male) with a first STEMI underwent serial assessments of LV longitudinal, circumferential and radial strains (LS, CS and RS) by selective tracking of subendocardial and subepicardial regions within 48 hours and a median of 5 months after PCI. LV mechanical parameters were compared with sixteen age and gender matched normal controls.

RESULTS

In comparison with controls, endocardial and epicardial LS were markedly attenuated at 48 hours following PCI (P < 0.001). An improvement in LV ejection fraction (EF > 5%) following PCI was seen in 24 (57%) patients and was associated with improvement in endocardial and epicardial LS (P < 0.001 and P = 0.003, respectively) and endocardial CS (P = 0.01). Radial strain and wall motion score index, however, remained persistently abnormal. The change in endocardial LS (OR 1.2, 95% CI 1.03 to 1.42, P = 0.01) and the change in epicardial LS (OR 1.2, 95% 1.03 to 1.46, P = 0.02) were significantly associated with the improvement in LVEF, independent of the location of STEMI and the presence of underlying multivessel disease.

CONCLUSIONS

In patients with STEMI treated by PCI, the recovery of LV subendocardial shortening strain seen in the longitudinal direction underlies the improvement in LV global function despite persistent abnormalities in radial mechanics and wall motion score index.

Relationship between left ventricular hypertrophy, hypertensive retinopathy, microalbuminuria and echocardiographic modalities in newly diagnosed hypertensive patients

Longitudinal myocardial function (LMF) may be impaired while systolic function is still normal. We investigated relationship between LMF and hypertensive organ damage in newly diagnosed stage I hypertensive patients. A total of 57 patient with never treated stage I hypertension and 48 matched healthy control subject were enrolled in the study. Conventional 2-D, Doppler and tissue wave Doppler imaging (TDI) echocardiography were used. LMF was evaluated by the septal and lateral strain (S) and strain rate (SR) measurements. Hypertensive complications were evaluated by the urine microalbumin levels and retinal examination. A multivariate regression analysis was perfomed to assess the relation between the variables. Ejection fraction, mid-wall fractional shortenning, systolic movement rates (TDs) in TDI were similar both in hypertensive and control groups. In patients with left ventricular hypertrophy, septal TDs (7.29 +/- 1.28 vs. 8.06 +/- 1.19 cm, P = 0.03), lateral TDs (8.46 +/- 1.83 vs. 9.87 +/- 2.42 cm, P = 0.01) and lateral S (-13.02 +/- 7.83 vs. -18.86 +/- 8.60%, P = 0.01) values were significantly lower. Septal S (-13.67 +/- 3.52 vs. -19.09 +/- 5.96%, P < 0.01) and SR (-0.83 +/- 0.29 vs. -1.22 +/- 0.28 1/S, P < 0.01) were significantly decreased in hypertensive patients with microalbuminuria. Septal S value was also significantly decreased in patients with retinopathy (-14.76 +/- 5.55 vs. -20.20 +/- 5.44%, P = 0.01). Multivariate analysis showed that only septal and lateral S values were independent factors for the retinopathy and left ventricular hypertrophy, respectively. In hypertensive patients, LMF established by the measurement of S and SR, might be impaired and also related with end organ damage while global circumferential function is preserved.

A new 2D-based method for myocardial velocity strain and strain rate quantification in a normal adult and paediatric population: assessment of reference values

BACKGROUND

Recent advances in technology have provided the opportunity for off-line analysis of digital video-clips of two-dimensional (2-D) echocardiographic images. Commercially available software that follows the motion of cardiac structures during cardiac cycle computes both regional and global velocity, strain, and strain rate (SR). The present study aims to evaluate the clinical applicability of the software based on the tracking algorithm feature (studied for cardiology purposes) and to derive the reference values for longitudinal and circumferential strain and SR of the left ventricle in a normal population of children and young adults.

METHODS

45 healthy volunteers (30 adults: 19 male, 11 female, mean age 37 +/- 6 years; 15 children: 8 male, 7 female, mean age 8 +/- 2 years) underwent transthoracic echocardiographic examination; 2D cine-loops recordings of apical 4-four 4-chamber (4C) and 2-chamber (2C) views and short axis views were stored for off-line analysis. Computer analyses were performed using specific software relying on the algorithm of optical flow analysis, specifically designed to track the endocardial border, installed on a Windows based computer workstation. Inter and intra-observer variability was assessed.

RESULTS

The feasibility of measurements obtained with tissue tracking system was higher in apical view (100% for systolic events; 64% for diastolic events) than in short axis view (70% for systolic events; 52% for diastolic events). Longitudinal systolic velocity decreased from base to apex in all subjects (5.22 +/- 1.01 vs. 1.20 +/- 0.88; p < 0.0001). Longitudinal strain and SR significantly increased from base to apex in all subjects (-12.95 +/- 6.79 vs. -14.87 +/- 6.78; p = 0.002; -0.72 +/- 0.39 vs. -0.94 +/- 0.48, p = 0.0001, respectively). Similarly, circumferential strain and SR increased from base to apex (-21.32 +/- 5.15 vs. -27.02 +/- 5.88, p = 0.002; -1.51 +/- 0.37 vs. -1.95 +/- 0.57, p = 0.003, respectively). Values of global systolic SR, both longitudinal and circumferential, were significantly higher in children than in adults (-1.3 +/- 0.2, vs. -1.11 +/- 0.2, p = 0.006; -1.9 +/- 0.6 vs. -1.6 +/- 0.5, p = 0.0265, respectively). No significant differences in longitudinal and circumferential systolic velocities were identified for any segment when comparing adults with children.

CONCLUSION

This 2D based tissue tracking system used for computation is reliable and applicable in adults and children particularly for systolic events. Measured with this technology, we have established reference values for myocardial velocity, Strain and SR for both young adults and children.