Measurement of strain and strain rate by echocardiography: ready for prime time?

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.

Left ventricular strain examination of different aged adults with 3D speckle tracking echocardiography

The purpose of this study was to identify traits of the left ventricular (LV) global longitudinal strain (GLS), global radial strain (GRS), global circular strain (GCS), and global area tracking (GAT) with three-dimensional speckle tracking echocardiography (3DSTE), and to determine the relationship between strain and age in healthy adults of different ages. A total of 153 volunteers were divided into young adult, middle-aged, and elderly groups, and examined with echocardiography to obtain general data and live two-dimensional (2D) images of the apical four-chamber view, which were assembled to obtain the full volume view of the LV. The images were then analyzed with 3DSTE software. Compared with the young adult and middle-aged groups, elderly adults demonstrated lower GLS, GRS, GCS, and GAT. Significant differences were not noted in GLS, GRS, and GCS between the young adult and middle-aged groups; however, the GAT of the middle-aged group was lower than that of the young adult group. The longitudinal strain (LS), radial strain (RS), and area tracking (AT) of 16 LV segments of the young adult group decreased gradually in level from the mitral valve to the apex, and increased in circular strain (CS). The LS, RS, CS, and AT of the middle-aged group also decreased gradually. The LS, RS, CS, and AT of the elderly people were highest from the mitral valve to the apex level and lowest at the papillary muscle. The results of this study demonstrated that LV GLS, GRS, GCS, and GAT decrease with age.

The effect of percutaneous coronary intervention of chronically totally occluded coronary arteries on left ventricular global and regional systolic function

BACKGROUND

Percutaneous coronary intervention (PCI) is frequently attempted to open chronic total occlusions (CTOs) and restore epicardial coronary flow. Data suggest adverse outcomes in the case of PCI failure. We hypothesized that failure to open a CTO might adversely affect regional cardiac function and promote deleterious cardiac remodelling, and success would improve global and regional cardiac function assessed using cardiac magnetic resonance and velocity vector imaging.

METHODS

Thirty patients referred for PCI to a CTO underwent cardiac magnetic resonance examination before and after the procedure. Left ventricular function and transmural extent of infarction was assessed in these patients. Regional cardiac function using Velocity Vector Imaging version 3.0.0 (Siemens) was assessed in 20 patients.

RESULTS

Successful CTO opening (thrombolysis in myocardial infarction 3 flow) occurred in 63% of patients. Left ventricular ejection fraction significantly increased after successful PCI (50 ± 13% to 54 ± 11%; P < 0.01). Global longitudinal strain (GLS) fell significantly in the failed group (Δ = -25 ± 17%; P = 0.02) in contrast with successful PCI in which GLS did not change (Δ 20 ± 32%; P = 0.17). GLS rate followed a pattern similar to GLS (failed, Δ -30 ± 17%; P < 0.01 vs success Δ 25 ± 48%; P = 0.34). In contrast, radial and circumferential strain/strain rate were not different between groups after success/failed PCI.

CONCLUSIONS

Regional cardiac function assessment using velocity vector imaging showed a significant decline in GLS and GLS rate in patients in whom PCI failed to open a CTO, with no change in global measures of cardiac function.

Right ventricular involvement in anterior myocardial infarction: a tissue Doppler-derived strain and strain rate study

OBJECTIVE

Strain and strain rate imaging is currently the most popular echocardiographic technique that reveals subclinical myocardial damage. There are currently no available data on this imaging method with regard to assessing right ventricular involvement in anterior myocardial infarction. Therefore, we aimed to evaluate right ventricular regional functions using a derived strain and strain rate imaging tissue Doppler method in patients who were successfully treated for their first anterior myocardial infarction.

METHODS

The patient group was composed of 44 patients who had experienced their first anterior myocardial infarction and had undergone successful percutaneous coronary intervention. Twenty patients were selected for the control group. The right ventricular myocardial samplings were performed in three regions: the basal, mid, and apical segments of the lateral wall. The individual myocardial velocity, strain, and strain rate values of each basal, mid, and apical segment were obtained.

RESULTS

The right ventricular myocardial velocities of the patient group were significantly decreased with respect to all three velocities in the control group. The strain and strain rate values of the right mid and apical ventricular segments in the patient group were significantly lower than those of the control group (excluding the right ventricular basal strain and strain rate). In addition, changes in the right ventricular mean strain and strain rate values were significant.

CONCLUSION

Right ventricular involvement following anterior myocardial infarction can be assessed using tissue Doppler based strain and strain rate.

Is strain by Speckle Tracking Echocardiography dependent on user controlled spatial and temporal smoothing? An experimental porcine study

Background

Speckle Tracking Echocardiography (STE) strain analysis relies on both spatial and temporal smoothing. The user is often allowed to adjust these smoothing parameters during analysis. This experimental study investigates how different degrees of user controllable spatial and temporal smoothing affect global and regional STE strain values in recordings obtained from normal and ischemic myocardium.

Methods

In seven anesthetized pigs, left ventricular short- and long-axis B-mode cineloops were recorded before and after left anterior descending coronary artery occlusion. Peak- and postsystolic global STE strain in the radial, circumferential and longitudinal direction as well as corresponding regional strain in the anterior and posterior walls were measured. During post-processing, strain values were obtained with three different degrees of both spatial and temporal smoothing (minimum, factory default and maximum), resulting in nine different combinations.

Results

All parameters for global and regional longitudinal strain were unaffected by adjustments of spatial and temporal smoothing in both normal and ischemic myocardium. Radial and circumferential strain depended on smoothing to a variable extent, radial strain being most affected. However, in both directions the different combinations of smoothing did only result in relatively small changes in the strain values. Overall, the maximal strain difference was found in normal myocardium for peak systolic radial strain of the posterior wall where strain was 22.0 ± 2.2% with minimal spatial and maximal temporal smoothing and 30.9 ± 2.6% with maximal spatial and minimal temporal smoothing (P < 0.05).

Conclusions

Longitudinal strain was unaffected by different degrees of user controlled smoothing. Radial and circumferential strain depended on the degree of smoothing. However, in most cases these changes were small and would not lead to altered conclusions in a clinical setting. Furthermore, smoothing did not affect strain variance. For all strain parameters, variance remained within the corresponding interobserver variance.

New three-dimensional speckle-tracking echocardiography identifies global impairment of left ventricular mechanics with a high sensitivity in childhood cancer survivors

BACKGROUND

The aim of this case-control study was to assess the usefulness of three-dimensional (3D) speckle-tracking echocardiography in the evaluation of global left ventricular (LV) myocardial performance in adolescent and adult survivors of childhood cancers.

METHODS

Fifty-three anthracycline-treated survivors of childhood cancers (mean age, 18.6 ± 5.1 years) and 38 controls were studied. Three-dimensional speckle-tracking echocardiography was performed to assess LV 3D global and segmental strain, time to peak segmental 3D strain, LV torsion, and ejection fraction. LV systolic dyssynchrony index (SDI) was calculated as the percentage of the standard deviation of times to peak strain of the 16 segments divided by the RR interval. A global performance index (GPI) was calculated as (global 3D strain × torsion)/SDI. The area under the receiver operating characteristic curve was calculated to determine the capability of various echocardiographic indices to discriminate between patients and controls.

RESULTS

Compared with controls, patients had significantly reduced LV global 3D strain (P < .001), torsion (P < .001), and GPI (P < .001) and greater SDI (P < .001). All except the basal anteroseptal segment in patients had reduced regional 3D strain compared with controls (P < .05 for all). Global 3D strain (P = .018), SDI (P = .003), and GPI (P = .02) were correlated with cumulative anthracycline dose. The areas under the curves for GPI, global 3D strain, 1/SDI, torsion, and ejection fraction were 0.92, 0.79, 0.79, 0.79, and 0.78, respectively. A GPI cutoff of 10.6°/cm had sensitivity of 84.9% and specificity of 81.6% of differentiating patients from controls.

CONCLUSIONS

Three-dimensional speckle-tracking echocardiography enables the derivation of an index of LV global performance that incorporates LV 3D strain, dyssynchrony, and torsion for the sensitive detection of altered LV mechanics in childhood cancer survivors.

Low doses of fludrocortisone and hydrocortisone, alone or in combination, on vascular responsiveness to phenylephrine in healthy volunteers

AIMS

A single administration of hydrocortisone has been shown to enhance the pressor response to phenylephrine in healthy volunteers and to norepinephrine in septic shock patients. Similar data do not exist for fludrocortisone. Since there continues to be disagreement about the utility of fludrocortisone in septic shock, we assessed the effects of a single administration of low doses of hydrocortisone (50 mg intravenously) and fludrocortisone (50 μg orally), given either alone or in combination, on phenylephrine mean arterial pressure and cardiac systolic and diastolic function dose-response relationships in 12 healthy male volunteers with hypo-aldosteronism induced by intravenous sodium loading.

METHODS

This was a placebo-controlled, randomized, double-blind, crossover study performed according to a 2 × 2 factorial design. Subjects received first a 2000 ml infusion of NaCl 0.9% during 2 h. Then fludrocortisone 50 μg (or its placebo) was administered orally and hydrocortisone 50 mg (or its placebo) was injected intravenously. At 1.5 h after treatment administration, incremental doses of phenylephrine were infused (from 0.01 to 3 μg kg(-1) min(-1)), each dose being infused during 5 min.

RESULTS

Both fludrocortisone (P < 0.001) and hydrocortisone (P = 0.002) induced a significant decrease in pressor response to phenylephrine, their effects being additive (fludrocortisone × hydrocortisone interaction, P = 0.792). The two drugs did not induce any detectable cardiac effect.

CONCLUSIONS

Single administrations of fludrocortisone and hydrocortisone decreased the pressor response to phenylephrine in healthy volunteers with hypo-aldosteronism. These similar effects of hydrocortisone and fludrocortisone probably express a rapid non-genomic vasodilating effect of the two steroids in the context of acute volume loading.

Detection of latent anthracycline-induced cardiotoxicity using left ventricular end-systolic wall stress-velocity of circumferential fiber-shortening relationship

Although cardiotoxicity is a well-known side effect of anthracycline, detection of subclinical impairment of myocardial contractility at the latent stage is difficult. The left ventricular end-systolic wall stress (WS)-velocity of circumferential fiber-shortening (VCF) relationship reflects the load-independent myocardial contractility and can detect sensitively intrinsic abnormalities in myocardial contractility. Usefulness of this relationship in detecting subclinical anthracycline-induced cardiotoxicity has not yet been established. We investigated whether latent anthracycline-induced cardiotoxicity at the subclinical state can be detected by using the WS-VCF relationship in patients receiving anthracycline therapy. We studied 45 patients who had received anthracycline therapy and 40 healthy controls. All patients had preserved left ventricular ejection fraction (LVEF). WS and VCF were measured using echocardiography. VCF was corrected by heart rate. The WS-VCF relationship was derived by linear regression. Patients with data points lying below -2 SD derived from controls were regarded as having impaired intrinsic myocardial contractility. Although VCF was within normal limits in all patients, it was significantly reduced in the patient group overall compared with the control group. On the other hand, WS was significantly increased in the patient group overall compared with the control group. The WS-VCF relationship demonstrated impaired intrinsic myocardial contractility in 24 patients (53.3 %). In more than half of patients with preserved LVEF, impairment of intrinsic myocardial contractility was detected using the WS-VCF relationship, suggesting the presence of latent anthracycline-induced cardiotoxicity. The WS-VCF relationship may be able to detect sensitively latent anthracycline-induced cardiotoxicity at the subclinical stage.

Changes in myocardial mechanics in patients with obesity following major weight loss after bariatric surgery

OBJECTIVE

The purpose of this study was to evaluate myocardial mechanics in obese subjects using 2D-speckle tracking echocardiography (2D-STE).

DESIGN AND METHODS

63 obese individuals, including 28 who underwent bariatric surgery for weight loss (BMI 51 ± 9 kg/m2) and 35 managed conservatively (BMI 43 ± 7 kg/m2 ) were included. Changes in strain (S) and strain rate (SR) measured by 2D-STE. Mean follow-up was 23 ± 10 months.

RESULTS

The surgery group had a significant weight loss (BMI 37 ± 10 kg/m2 , P < 0.0001), but no change was noted in the nonsurgery group (BMI 42 ± 7 kg/m2 , P = 0.1). For the surgery group, S and SR in early diastole (SRe) improved significantly in the longitudinal left ventricle (LV) (S: P = 0.0004, SRe: P = 0.02) and right ventricle (RV) (S: P = 0.02, SRe: P = 0.009), whereas no changes were seen in LV ejection fraction (LVEF). In the nonsurgery group, there was no change in S, SR, or body weight. For all patients, weight changes correlated significantly with changes in LV S (r = 0.43, P = 0.0005).

CONCLUSIONS

The improvement of S after bariatric surgery suggests that weight loss could improve myocardial performance, despite the lack of change in LVEF.

Acute right ventricular pressure overload compromises left ventricular function by altering septal strain and rotation

While right ventricular (RV) dysfunction has long been known to affect the performance of left ventricle (LV), the mechanisms remain poorly defined. Recently, speckle-tracking echocardiography has demonstrated that preservation of strain and rotational dynamics is crucial to both LV systolic and diastolic function. We hypothesized that alteration in septal strain and rotational dynamics of the LV occurs during acute RV pressure overload (RVPO) and leads to decreased cardiac performance. Seven anesthetized pigs underwent median sternotomy and placement of intraventricular pressure-volume conductance catheters. Two-dimensional echocardiographic images and LV pressure-volume loops were acquired for offline analysis at baseline and after banding of the pulmonary artery to achieve RVPO (>50 mmHg) induced RV dysfunction. RVPO resulted in a significant decrease (P < 0.05) in LV end-systolic elastance (50%), systolic change in pressure over change in time (19%), end-diastolic volume (22%), and cardiac output (37%) that correlated with decrease in LV global circumferential strain (58%), LV apical rotation (28%), peak untwisting (reverse rotation) rate (27%), and prolonged time to peak rotation (17%), while basal rotation was not significantly altered. RVPO reduced septal radial and circumferential strain, while no other segment of the LV midpapillary wall was affected. RVPO decreased septal radial strain on LV side by 27% and induced a negative radial strain from 28 ± 5 to -16 ± 2% on the RV side of the septum. The septal circumferential strain on both LV and RV side decreased by 46 and 50%, respectively, following RVPO (P < 0.05). Our results suggest that acute RVPO impairs LV performance by primarily altering septal strain and apical rotation.

Proximal aortic compliance and diastolic function assessed by speckle tracking imaging

PURPOSE

Speckle tracking imaging (STI) is a recent technique that evaluates an echocardiographic image throughout the cardiac cycle and provides dynamic variables such as tissue velocities and strain rates. The objective of our study was to determine 1) if STI can be used to quantify proximal aortic compliance and 2) if decreased aortic compliance determined by STI will reproduce the previously reported correlation with diastolic function.

METHODS

This was a retrospective observational case series using previously obtained intraoperative transesophageal images. Diastolic performance was quantified by STI-based longitudinal velocities of the basal-septal and basal-lateral walls of the left ventricle in early diastole (LV E'). Change in proximal aortic volume was calculated using STI to measure peak longitudinal and radial velocities in early diastole. After normalizing for mean arterial pressure, compliance was calculated and then compared with basal-septal and basal-lateral LV E' using single regression analysis.

RESULTS

Twenty patients were included in our analysis. Linear regression of basal-septal LV E' and basal-lateral LV E' vs proximal aortic compliance during diastole each resulted in an R(2) value of 0.26 (P < 0.05).

CONCLUSION

Speckle tracking can be used to describe the physical motion of the aortic wall and to calculate its compliance. We confirm that variation in diastolic function can be attributed, in part, to aortic compliance. Our novel approach of measuring compliance throughout the cardiac cycle, isolating radial and longitudinal contributions, and evaluating previously obtained images retrospectively provides advantages over previously reported measures of aortic compliance. Speckle tracking promises new insights into ventricular function, aortic mechanics, and the interaction between these structures.

Left ventricular myocardial performance in patients with dengue hemorrhagic fever and thrombocytopenia as assessed by two-dimensional speckle tracking echocardiography

OBJECTIVES

We obtained longitudinal, radial and circumferential strains in patients with dengue hemorrhagic fever (DhF) and thrombocytopenia using two-dimensional (2D) speckle tracking echocardiography to analyze left ventricular (LV) myocardial performance.

METHODS

In this prospective study, 2D echocardiographic images of the left ventricle in the four-, three- and two-chamber views and parasternal short-axis views at the basal, mid and apical levels were obtained in 40 subjects: 20 patients (23 ± 8 years, 12 male) with DhF and thrombocytopenia and 20 healthy controls (23 ± 5 years, 11 male). Of the 20 patients, imaging was performed again in 19 at discharge after a hospital stay of 8 ± 1 days. Longitudinal, circumferential and radial strains were quantified and compared in an 18-segment model using a novel speckle tracking system.

RESULTS

Left ventricular global ejection fraction was reduced in patients with DhF at presentation as compared with controls (51.25 ± 0.96% vs. 59.32 ± 1.26%; p = 0.032). Peak longitudinal strain in patients with DhF was significantly attenuated in the subendocardial region compared with normal controls (p < 0.001). A significant increase in circumferential strain for patients with DhF was evident only in the subepicardial region (p = 0.009). Patients with DhF showed significantly higher radial strain than controls (p < 0.001). On multivariate analysis, subendocardial longitudinal strain independently predicted the duration of hospital stay in patients with DhF.

CONCLUSION

Assessment of speckle tracking echocardiography-derived LV mechanics helps in understanding myocardial mechanics in patients with DhF and thrombocytopenia. Identification of reduced LV longitudinal strain helps in understanding the mechanism of reduced LV myocardial performance seen in patients with DhF.

Myocardial sympathetic innervation, function, and oxidative metabolism in non-infarcted myocardium in patients with prior myocardial infarction

OBJECTIVE

The purpose of this study was to investigate the relationship between sympathetic innervation, contractile function, and the oxidative metabolism of the non-infarcted myocardium in patients with prior myocardial infarction.

METHODS

In 19 patients (14 men, 5 women, 65 ± 9 years) after prior myocardial infarction, sympathetic innervation was assessed by (11)C-hydroxyephedrine (HED) positron emission tomography (PET). Oxidative metabolism was quantified using (11)C-acetate PET. Left ventricular systolic function was measured by echocardiography with speckle tracking technique.

RESULTS

The (11)C-HED retention was positively correlated with left ventricular ejection fraction (LVEF) (r = 0.566, P < 0.05), and negatively with peak longitudinal strain in systole in the non-infarcted myocardium (r = -0.561, P < 0.05). Kmono, as an index of oxidative metabolism, was significantly correlated with rate pressure product (r = 0.649, P < 0.01), but not with (11)C-HED retention (r = 0.188, P = 0.442). Furthermore, there was no significant correlation between Kmono and LVEF (r = 0.106, P = 0.666) or peak longitudinal strain in systole (r = -0.256, P = 0.291) in the non-infarcted myocardium. When the patients were divided into two groups based on the median value of left ventricular end-systolic volume index (LVESVI) (41 mL), there were no significant differences in age, sex, and rate pressure product between the groups. However, the large LVESVI group (>41 mL) was associated with reduced (11)C-HED retention and peak longitudinal strain in systole, whereas Kmono was similar between the groups.

CONCLUSIONS

This study indicates that remodeled LV after myocardial infarction is associated with impaired sympathetic innervation and function even in the non-infarcted myocardial tissue. Furthermore, oxidative metabolism in the non-infarcted myocardium seems to be operated by normal regulatory mechanisms rather than pre-synaptic sympathetic neuronal function.

Reduced right ventricular myocardial strain in the elite athlete may not be a consequence of myocardial damage. "Cream masquerades as skimmed milk"

BACKGROUND

Latest research shows that the lower resting values of right ventricular (RV) myocardial % strain may represent a physiologic change rather than subclinical myocardial damage. Therefore, we assessed load-independent changes to the RV as a consequence of high intensity training by measuring the Isovolumic acceleration (IVA) of the free wall of the RV in conjunction with NT pro-BNP measured by an electrochemiluminescence assay.

METHODS

Seventeen controls (mean age 27 ± 4), 24 soccer footballers (mean age 24 ± 4), and 18 elite rowers (mean age 22 ± 4) were studied. Left ventricular (LV) and RV % strain were measured using two-dimensional (2D) speckle based automated functional imaging (AFI) software. RV free wall IVA was measured using pulsed-wave tissue Doppler at the lateral tricuspid annulus. Standard 2D echo were used to measured RV parameters including the Tei index (systolic and diastolic function) and the total annular plane systolic excursion (TAPSE) of the RV annulus. NT pro-BNP was measured by an electrochemiluminescence assay.

RESULTS

The RV diameter was increased in the footballers and elite rowers compared with controls (P < 0.001). RV wall size was greater in the elite rowers compared with controls and footballers (P = 0.002). The peak IVA of the RV was higher in the rowers, compared with the footballers and to controls (P < 0.001). The mean LV and RV % myocardial strain were lower in the elite athletes and the footballers compared with controls (P < 0.001). There was no difference in RV Tei index, levels of BNP, and TAPSE across all subjects.

CONCLUSIONS

This study showed a significant increase in IVA of the RV of athletes despite reduced myocardial % strain and normal levels in NT-proBNP. This suggests that the decrease in % strain is not a consequence of myocardial damage, but may represents a part of the physiological response to endurance exercise. Therefore, a reduced IVA in a remodeled RV could herald a pathological response.

Normal values for longitudinal tissue velocity and strain rate imaging in individual segments of the left and right ventricles of healthy adult hearts

OBJECTIVES

To quantify the normal peak mean systolic velocities and strain rate parameters in the left ventricle (LV) and right ventricle (RV) and define their regional differences in normal adult hearts.

METHODS

Sixty-nine healthy volunteers (42% male; mean age ± SD, 30.03 ± 5.35 years) underwent color tissue Doppler and strain rate imaging. The first and second peak mean systolic velocities, peak strain, and strain rate in the systolic ejection phase were determined for 16 LV segments, the apex (17th segment), and 3 RV free wall segments.

RESULTS

The first peak mean systolic velocity was measurable in less than 50% of segments in the inferior and septal (-posterior) walls and RV free wall and in greater than 70% of segments of the other LV walls. The first and second peak mean systolic velocities of all LV walls and the RV free wall decreased significantly from the basal to apical region (P < .001).The strain and strain rate in the lateral and anterior walls decreased significantly from base to apex, whereas the anteroseptal and posterior walls were homogeneous. The strain rate in the inferior wall increased remarkably from base to apex, whereas it decreased significantly from the mid level to the apex. The strain in the RV was homogeneous, whereas the strain rate decreased significantly from the mid level to the apex. The apex (17th segment) showed the lowest value for each of the study parameters.

CONCLUSIONS

Longitudinal velocities decreased from base to apex, whereas deformation measurements did not show uniform patterns in LV walls and the RV free wall. In most cases, there are 1 peak systolic velocity in the inferior and septal (-posterior) walls and 2 peak systolic velocities in the other 4 LV walls.

Assessment of left atrial function after percutaneous closure of patent foramen ovale

BACKGROUND

The influence of atrial septal occluders in left atrial (LA) function after percutaneous closure of patent foramen ovale (PFO) has not been thoroughly studied.

METHODS

Twenty-five patients (mean age 40.7 ± 12 years) undergoing percutaneous PFO closure were enrolled in this study. Transthoracic echocardiogram (TTE) was performed 3 and 6 months before the procedure. Volumetric indices (active emptying fraction: LA AEF, expansion index: LA EI, and passive emptying fraction: LA PEF), strain and strain rate (SR), were calculated during the contractile, reservoir, and conduit LA phases for the lateral, anterior, and inferior LA walls with TTE.

RESULTS

After 3 months, a decrease in the SR of the LA anterior wall was observed (from 2.12 ± 0.22 to 1.66 ± 0.26, P < 0.045), while the LA lateral wall strain was found to be increased (from 0.708 ± 0.15 to 0.783 ± 0.159, P < 0.001). Moreover, simultaneously LA AEF was greater compared with baseline (from 31.0 ± 1.6 to 34.0 ± 1.6, P < 0.004). However, all these alterations reversed at 6 months.

CONCLUSIONS

Segmental LA function is altered transiently after percutaneous PFO closure with a septal occlude. The LA anterior wall SR decreases, while the lateral wall strain increases. The impact of these alterations needs further clarification.

Effect of stellate ganglia stimulation on global and regional left ventricular function as assessed by speckle tracking echocardiography

Left ventricular (LV) twist mechanics and regional strain during cardiac sympathetic efferent activation are poorly understood. The purpose of this study was to compare the effects of left stellate ganglia (LSG) and right stellate ganglia (RSG) stimulation on cardiac twist/untiwst mechanics and regional strain. In nine pigs, echocardiographic imaging and LV pressure-volume measurements were performed before and during unilateral and bilateral stellate ganglion stimulation. LSG and RSG stimulation significantly augmented LV end-systolic pressure by 24% and 22% (P < 0.01), maximal rate of LV pressure change by 167% and 165% (P < 0.01), and time constant of LV relaxation by 20% and 12% (P < 0.01), respectively. RSG stimulation resulted in a greater chronotropic response than LSG stimulation (RSG: 68% vs. LSG: 12%, P < 0.01). Both LSG and RSG stimulation significantly increased global epicardial and endocardial LV rotation and diastolic untwisting rate and reduced the time to peak rotation (P < 0.05). However, LSG stimulation predominantly increased radial and circumferential strain in the LV inferoseptal, inferior, posterior, and lateral regions, whereas RSG stimulation primarily increased radial and circumferential strain in the anteroseptal, anterior, and lateral LV regions. Stimulation of both stellate ganglia led to a uniform increase in all LV segments. Our data suggest that LSG and RSG stimulation lead to a global increase in LV twist, driven by distinct regional strain heterogeneity that may result from myocardial innervation from the LSG and RSG. These findings provide a better understanding of the global and regional functional consequences of regional myocardial innervation from the LSG and RSG.

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.

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.

NT-proBNP correlated with strain and strain rate imaging of the right ventricle before and after transcatheter closure of atrial septal defects

BACKGROUND

Atrial septal defects (ASD) account for 10% of all congenital heart lesions and represent the third most congenital cardiac defect seen in adults.

OBJECTIVES

Using strain and strain rate imaging (SRI) to assess right ventricular (RV) function in patients with ASD and correlate the results with the level of N-terminal pro-brain natriuretic peptide (NT-proBNP) before and after transcatheter closure.

METHODS

At the Hungarian Institute of Cardiology, 27 females and 18 males (mean age 21.53 years) were diagnosed with ASD and admitted for percutaneous closure. Echocardiography was done to assess theleft ventricular (LV), RV and left atrial (LA) diameters. For assessment of systolic RV function, we measured Tricuspid annular plane systolic excursion (TAPSE), strain, and SRI. Amplatzer ASD closure was done under general anesthesia. NT-proBNP levels were measured before and three months after closure.

RESULTS

ASD closure was achieved in all patients. The mean ASD diameter was 15.15 mm. The size of the occluder ranged from 10 to 24 mm. The mean LA diameter in the pre-closure group was significantly higher than the control; mean left ventricular end diastolic diameter (LVEDD) showed a non-significant difference from either the control group or the post-closure group, while the mean right ventricular end diastolic diameter (RVEDD) markedly reduced post-closure, and it was significantly higher than the control group. Global RV strain and peak systolic strain rate (PSSR) were significantly higher in ASD group than in the control. The NT-proBNP levels were found to be correlated with pulmonary arterial pressure (PAP), TAPSE, global RV strain and PSSR.

CONCLUSION

Volume overload induced by ASD is associated with increased strain values, which return to normal after closure. NT-proBNP is a parameter which correlates to RV pressure, PAP and the amount of shunt volume caused by an ASD.

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.

Cardiac dysfunction and prolonged hemodynamic deterioration after implantable cardioverter-defibrillator shock in patients with systolic heart failure

BACKGROUND

We investigated the acute effects of implantable cardioverter-defibrillator shock on myocardium, cardiac function, and hemodynamics in relation to left ventricular systolic function.

METHODS AND RESULTS

We studied 50 patients who underwent implantable cardioverter-defibrillator implantation and defibrillation threshold (DFT) testing: 25 patients with left ventricular ejection fraction (LVEF) ≥ 45% and 25 patients with LVEF <45%. We measured cardiac biomarkers (creatine kinase, creatine kinase-MB, myoglobin, cardiac troponin T and I, and N-terminal probrain natriuretic peptide). Left ventricular relaxation was assessed by global longitudinal strain rate during the isovolumetric relaxation period using speckle-tracking echocardiography. Blood sampling and echocardiography were performed before, immediately after, and 5 minutes and 4 hours after DFT testing. Mean arterial pressure was measured directly during DFT testing. Cardiac biomarkers showed no significant changes in either group. LVEF was decreased until 5 minutes after DFT testing and had recovered to the baseline at 4 hours in the group with reduced LVEF (P<0.001), whereas LVEF reduction was not observed in the group with preserved LVEF (P=0.637). Global isovolumetric relaxation period was decreased until 5 minutes after DFT testing and had recovered to the baseline at 4 hours in both groups (preserved LVEF: 0.39 ± 0.14 versus 0.23 ± 0.13* versus 0.23 ± 0.13* versus 0.40 ± 0.13 s(-1), *P<0.001 versus baseline; reduced LVEF: 0.15 ± 0.05 versus 0.08 ± 0.04† versus 0.09 ± 0.04† versus 0.15 ± 0.05 s(-1), †P<0.001 versus baseline, repeated-measures ANOVA). Time to recovery of mean arterial pressure to the baseline was prolonged in the group with reduced LVEF (P<0.001).

CONCLUSIONS

Implantable cardioverter-defibrillator shock transiently impairs cardiac function and hemodynamics especially in patients with systolic dysfunction, although significant tissue injury is not observed.

Evaluation of myocardial deformation in patients with sickle cell disease and preserved ejection fraction using three-dimensional speckle tracking echocardiography

BACKGROUND

Sickle cell disease (SCD) is a hemoglobinopathy that affects one in 500 African Americans. Although it is well established that patients with SCD have left ventricular (LV) diastolic dysfunction, it is not clear whether they have subtle LV systolic dysfunction despite preserved ejection fraction (EF). We used three-dimensional speckle tracking echocardiography (3DSTE) to assess changes in both systolic and diastolic LV function in SCD.

METHODS

Transthoracic real time 3D images were obtained (Philips iE33) in 56 subjects, including 28 stable outpatients with SCD (age 33 ± 7 years) and 28 normal controls (age 35 ± 9 years). 3DSTE was performed using prototype software (4DLV Analysis, TomTec) to obtain LV volume and deformation time curves, from which indices of systolic and diastolic LV function were calculated.

RESULTS

In SCD patients, 3DSTE-derived LV filling parameters were significantly different from normal controls, reflecting an increase in both rapid and atrial filling volumes and prolonged active relaxation, depicted by a decrease in filling volume fractions at fixed times and an increase in rapid filling duration. Global LV systolic function was not only preserved but increased compared to controls, as reflected by significantly increased global longitudinal strain. Importantly, twist angle and torsion as well as radial and circumferential components of 3D strain were similar in both groups.

CONCLUSIONS

3DSTE was able to confirm diastolic dysfunction, as expected in some patients with SCD. However, 3DSTE strain analysis did not reveal any changes in LV systolic function. These findings provide novel insight into the pathophysiology of the cardiovascular complications of SCD.

Abnormal cardiac strain in children and young adults with HIV acquired in early life

BACKGROUND

Traditional measures of cardiac function are now often normal in adolescents and young adults treated with antiretroviral therapy for human immunodeficiency virus (HIV) infection. There is, however, evidence of myocardial abnormalities in adults with HIV. Cardiac strain analysis may detect impairment in cardiac function that may be missed by conventional measurements in this population.

METHODS

This was a retrospective study in which echocardiograms of HIV-infected subjects (n = 28) aged 7 to 29 years who participate in a natural history study of HIV acquired early in life were analyzed and compared with matched controls. Standard echocardiographic measures, along with speckle tracking-derived strain and strain rate, were assessed.

RESULTS

Among the HIV-infected subjects, the median CD4 count was 667 cells/mm(3), and the mean duration of antiretroviral therapy was 14.6 years. Ejection fractions and fractional shortening were normal. There were no significant differences in measures of systolic or diastolic function between the groups. The HIV-infected group had borderline increased left ventricular mass indices. Global longitudinal and circumferential strain and strain rate, as well as global radial strain rate, were significantly impaired in the HIV-infected group compared with controls. There were no associations identified between left ventricular mass index or strain indices and current CD4 count, CD4 nadir, HIV viral load, or duration of antiretroviral therapy.

CONCLUSIONS

HIV-infected participants demonstrated impaired strain and strain rate despite having normal systolic function and ejection fractions. Strain and strain rate may prove to be prognostic factors for long-term myocardial dysfunction. Therefore, asymptomatic children and young adults with long-standing HIV infection may benefit from these more sensitive measures.

Effect of embolic particles during coronary interventional procedures on regional wall motion in patients with stable angina pectoris

Microembolization during percutaneous coronary intervention (PCI) causes minor myocardial injury, and a Doppler guidewire can detect embolic particles as high-intensity transient signals (HITS). The present study investigated the effect of microembolization during PCI on regional wall motion using a Doppler guidewire and myocardial strain analysis. We performed PCI to the left anterior descending coronary artery in 25 patients (18 men and 7 women, 68 ± 8 years old) with stable angina pectoris. Coronary flow spectrums were obtained with a Doppler guidewire to count the total number of HITS throughout the PCI procedures. On the days before and after PCI, we recorded echocardiography and measured the longitudinal peak systolic strain, peak strain rate, and early diastolic strain rate in the left anterior descending territory using a 2-dimensional speckle tracking method. PCI was successfully performed, and 10 ± 6 HITS (range 0 to 22, median 9) were recognized during PCI. The echocardiographic study showed no visible wall motion abnormalities in the left anterior descending territory either after or before PCI. In cases in which the total number of HITS was ≥10, the peak systolic strain, peak strain rate, and early diastolic strain rate worsened on the day after PCI compared with those on the day before PCI (p <0.01). The rates of change in peak systolic strain and early diastolic strain rate, defined as the ratios of those parameters after PCI to those before PCI, had modest to strong inverse correlations with the total number of HITS (R(2) = 0.35 and R(2) = 0.46, respectively). In conclusion, periprocedural microembolization during PCI reduces subclinical cardiac function in patients with stable angina pectoris.

Left ventricular function quantified by myocardial strain imaging in small-breed dogs with chronic mitral regurgitation

BACKGROUND

The presence of left ventricular (LV) systolic dysfunction may influence prognosis or therapy in dogs with chronic mitral regurgitation (MR). Assessment of LV function in MR by conventional echocardiography is confounded by altered ventricular loading. Myocardial deformation (strain) imaging might offer more sensitive estimates of LV function in this disease.

OBJECTIVE

Prospectively measure myocardial strain in dogs with asymptomatic MR compared to a control group.

ANIMALS, MATERIALS AND METHODS

Forty healthy dogs (3.5-11.5 kg): 20 Controls; 20 dogs with MR and LV remodeling (Stage B2), were evaluated in this study. LV size and function were assessed in a short-axis plane. Segmental radial strain and strain rate and global circumferential strain were measured using a 2D echocardiographic speckle-tracking algorithm (GE EchoPAC). Groups were compared using Bonferroni t-tests. Influences of heart rate and body weight were explored with linear regression.

RESULTS

The MR group had significantly greater mean values for heart rate, LV size, and LV systolic function. Specifically, LV diastolic diameter, diastole area, shortening fraction, averaged peak systolic and early diastolic radial strain, global circumferential strain, and averaged radial strain rate were significantly greater in the MR group (p < 0.015 to p < 0.001). Strain was unrelated to weight, but weakly correlated with heart rate.

CONCLUSIONS

Similar to conventional indices, Stage B2 dogs with MR demonstrate hyperdynamic deformation in the short-axis plane. Short-axis strain variables measured by 2D speckle tracking are greater than for controls of similar age and weight. These results imply either preserved LV systolic function or that LV dysfunction is masked by altered ventricular loading.

Multi-channel pre-beamformed data acquisition system for research on advanced ultrasound imaging methods

The lack of open access to the pre-beamformed data of an ultrasound scanner has limited the research of novel imaging methods to a few privileged laboratories. To address this need, we have developed a pre-beamformed data acquisition (DAQ) system that can collect data over 128 array elements in parallel from the Ultrasonix series of research-purpose ultrasound scanners. Our DAQ system comprises three system-level blocks: 1) a connector board that interfaces with the array probe and the scanner through a probe connector port; 2) a main board that triggers DAQ and controls data transfer to a computer; and 3) four receiver boards that are each responsible for acquiring 32 channels of digitized raw data and storing them to the on-board memory. This system can acquire pre-beamformed data with 12-bit resolution when using a 40-MHz sampling rate. It houses a 16 GB RAM buffer that is sufficient to store 128 channels of pre-beamformed data for 8000 to 25 000 transmit firings, depending on imaging depth; corresponding to nearly a 2-s period in typical imaging setups. Following the acquisition, the data can be transferred through a USB 2.0 link to a computer for offline processing and analysis. To evaluate the feasibility of using the DAQ system for advanced imaging research, two proof-of-concept investigations have been conducted on beamforming and plane-wave B-flow imaging. Results show that adaptive beamforming algorithms such as the minimum variance approach can generate sharper images of a wire cross-section whose diameter is equal to the imaging wavelength (150 μm in our example). Also, planewave B-flow imaging can provide more consistent visualization of blood speckle movement given the higher temporal resolution of this imaging approach (2500 fps in our example).

Systemic sclerosis and the heart: current diagnosis and management

PURPOSE OF REVIEW

When present clinically, cardiac involvement in systemic sclerosis (SSc) is a major risk factor for death. It is therefore vitally important to understand the epidemiology, screening, diagnosis, and treatment of the cardiac manifestations of SSc.

RECENT FINDINGS

The epidemiology of cardiac involvement in SSc has been the subject of several recent studies. Most importantly, the prevalence of overt left ventricular (LV) systolic dysfunction and its associated risk factors have been defined, and patients with diffuse cutaneous SSc appear to be most susceptible to direct cardiac involvement. From a diagnostic and screening standpoint, tissue Doppler echocardiography and natriuretic peptides have provided fresh insight into subclinical cardiac dysfunction in SSc. Newer techniques, such as speckle-tracking echocardiography, diffuse myocardial fibrosis imaging, and absolute myocardial perfusion imaging, are poised to further advance our knowledge. Lastly, there is now consistent observational data to suggest a central role for calcium channel blockers in the treatment of microvascular ischemia and prevention of overt LV systolic dysfunction, although randomized controlled trials are lacking.

SUMMARY

Recent studies have improved our understanding of cardiac involvement in SSc. Nevertheless, key questions regarding screening, diagnosis, and treatment remain. Novel diagnostic techniques and multicenter studies should yield important new data, which will hopefully ultimately result in improved outcomes.

Irbesartan prevents myocardial remodeling in experimental thyrotoxic cardiomyopathy

This study evaluated the effects of irbesartan and propranolol on thyroid hormone (TH)-induced cardiac functional and structural remodeling. A rat model of thyrotoxicosis was established by daily intraperitoneal injections of L-thyroxine (T(4), 100 μg/kg) for 4 weeks. Forty Sprague-Dawley rats were randomly divided into four groups (n = 10 each): control group, T(4) group (T(4) alone), T(4) plus irbesartan group (T(4)-Irb, 30 mg/kg), and T(4) plus propranolol group (T(4)-Pro, 0.5mg/mL of drinking water). Cardiac chamber size and functional parameters were measured by echocardiography and cardiomyocyte diameter. Heart rate (HR) and cardiac fibrosis were determined. T(4) alone showed significantly increased HR and cardiomyocyte width (25.0 ± 1.77 vs. 18.8 ± 0.84 μm, P < 0.001) with fibrosis, reduced left ventricle (LV) longitudinal strain (S(long); -16.0 ± 6.27 vs. -22.7 ± 5.19 %, P < 0.001) compared with control. When compared with T(4) alone, T(4)-Irb showed significantly improved LV S(long) (-21.4 ± 1.84 vs. -16.0 ± 6.27 %, P =0.017) and reduced cardiomyocyte width (21.0 ± 1.0 vs. 25.0 ± 1.77 μm, P =0.002) with comparable HR (458.4 ± 24.3 vs. 486.6 ± 30.1 bpm, P = 0.086). However, T(4)-Pro showed significantly reduced HR with improved LV S(long) without alteration of cardiomyocyte width and fibrosis compared with T(4) alone. In conclusion, renin-angiotensin system (RAS) blocking by irbesartan could significantly attenuate TH-induced cardiac structural and functional remodeling. However, HR reduction by propranolol could not alternate structural remodeling, which may implicate the RAS as having an important role in thyrotoxic cardiomyopathy beyond tachycardia.

Newer Doppler echocardiography techniques in assessment of heart function in obese patients

Obesity is one of the major health problems of modem society. The prevalence of this condition has increased at an alarming rate, especially the most severe form (body mass index >40 kg/m2). The cardiovascular problems that generally accompany obesity are the focus of a large number of studies. Conventional echogram and more current modalities, such as tissue Doppler, strain and strain rate are valuable tools for the detection of subclinical dysfunction and the early diagnosis and treatment of patients.