Measurement of right ventricular mechanical synchrony in children using tissue Doppler velocity and two-dimensional strain imaging

Prognostic value of right ventricular dyssynchrony in adults with repaired tetralogy of Fallot

OBJECTIVE

Residual sequelae after surgical repair of tetralogy of Fallot (rTOF) affect clinical outcome. We investigated the prognostic impact of right ventricular (RV) dyssynchrony in adults with rTOF years after the surgical repair.

METHODS

Patients from the Swiss Adult Congenital HEart disease Registry were included. NT-proBNP levels, echocardiography, exercise testing and MRI data were collected. An offline strain analysis to quantify RV-ventricular and interventricular dyssynchrony was performed. The standard deviation of the time-to-peak shortening (TTP) of six RV segments defined the RV Dyssynchrony Index (RVDI). Maximal difference of TTP between RV and left ventricular segments defined the interventricular shortening delay (IVSD). Predictors of a composite adverse event (arrhythmias, hospitalisation for heart failure and death) were identified by multivariate Cox regression analysis. Their median values were used to create a risk score.

RESULTS

Out of 285 included patients (mean age 34±14 years), 33 patients (12%) experienced an adverse event during a mean follow-up of 48±21 months. No correlation was found between RVDI, IVSD and clinical events. NT-proBNP, right atrial area and peak heart rate were independent predictors of outcomes. After 4 years-follow-up, no adverse events occurred in patients at low risk (score=0 points), while an adverse event occurred in 62% of patients at high risk (score=3 points, p<0.001).

CONCLUSION

In our cohort of adults with rTOF, surrogates of RV dyssynchrony did not correlate with outcomes. A multimodality approach was effective in predicting the risk for adverse events.

Right ventricular electromechanical dyssynchrony in adults with repaired Tetralogy of Fallot

Background and purpose

Electromechanical dyssynchrony, manifested by right bundle branch block and regional wall mechanical dysfunction, contributes to inefficient RV function in repaired Tetralogy of Fallot (ToF). This study aims to evaluate the synchronicity of multiple RV walls using two-dimensional multi-plane echocardiography (2D-MPE) in order to augment current understanding of the mechanisms behind RV dyssynchrony.

Methods

Sixty-nine adult ToF patients [aged 33 (23-45) years; 61% male] and twenty-five matched healthy controls underwent deformational analysis of the RV lateral, anterior, inferior and septal walls following 2D-MPE acquisitions. RV synchronicity was assessed by the intra-RV deformation delay between each basal RV wall and mid-septal segment in addition to mechanical dispersion calculated across four, six and eight segments (MD).

Results

All RV wall-septum delays plus MD-4 and MD-6 indices were significantly greater in ToF patients compared to healthy controls (p < 0.001-0.03). In ToF patients, the lateral and anterior RV walls were last to reach peak deformation and anterior wall longitudinal strain was lower (p = 0.001). Post systolic shortening of at least one RV wall segment was identified in 19 (28%) ToF patients. Despite similar ECG characteristics, lateral and anterior wall-septum delays were significantly longer in patients with greater degrees of dyssynchrony (73 [37-108]ms vs. 37 [0-63]ms, p = 0.006; 91 [52-116]ms vs. 41 [1-69]ms, p = 0.013), although RV ejection fraction (RVEF) was not significantly lower. MD-4 and MD-8 indices displayed moderate negative associations with RVEF, strengthened by inclusion of lateral wall longitudinal strain (r = 0.64/0.65; p ≤0.01).

Conclusion

RV dyssynchrony in ToF is characterised by electromechanical delays between the lateral, anterior and septal walls, with anterior wall dysfunction likely associated with surgical repair of the RV outflow tract. Prospectively, 2D-MPE may have an emerging role evaluating RV mechanical response to electrical resynchronisation therapy.

Impact on right ventricular performance in patients undergoing permanent pacemaker implantation: Left bundle branch pacing versus right ventricular septum pacing

BACKGROUND

The novel method of left bundle branch pacing (LBBP) has been reported to achieve better electrical and mechanical synchrony in the left ventricle than conventional right ventricular pacing (RVP). However, its effects on right ventricle (RV) performance are still unknown.

METHODS

Consecutive patients undergoing dual-chamber pacemaker (PM) implantation for sick sinus syndrome (SSS) with normal cardiac function and a narrow QRS complex were recruited for the study. The pacing characteristics and echocardiogram parameters were measured to evaluate RV function, interventricular and RV synchrony, and were compared between ventricular pacing-on and native-conduction modes.

RESULTS

A total of 84 patients diagnosed with SSS and an indication for pacing therapy were enrolled. Forty-two patients (50%; mean age 65.50 ± 9.30 years; 35% male) underwent successful LBBP and 42 patients (50%; mean age 69.26 ± 10.08 years; 33% male) RVSP, respectively. Baseline characteristics were similar between the two groups. We found no significant differences in RV function [RV-FAC (Fractional Area Change)%, 47.13 ± 5.69 versus 48.60 ± 5.83, p = .069; Endo-GLS (Global Longitudinal Strain)%, -28.88 ± 4.94 versus -29.82 ± 5.35, p = .114; Myo-GLS%, -25.72 ± 4.75 versus -25.72 ± 5.21, p = .559; Free Wall St%, 27.40 ± 8.03 versus -28.71 ± 7.34, p = .304] between the native-conduction and LBBP capture modes, while the RVSP capture mode was associated with a significant reduction in the above parameters compared with the native-conduction mode (p < .0001). The interventricular synchrony in the LBBP group was also superior to the RVSP group significantly.

CONCLUSION

LBBP is a pacing technique that seems to associate with a positive and protective impact on RV performance.

Quantification of Right Ventricular Electromechanical Dyssynchrony in Relation to Right Ventricular Function and Clinical Outcomes in Children with Repaired Tetralogy of Fallot

BACKGROUND

Electromechanical dyssynchrony occurs ubiquitously following tetralogy of Fallot (TOF) repair, manifesting electrically as a wide QRS duration and mechanically as a right-sided septal/apical flash. Early septal activation and prestretch of the right ventricular (RV) basal lateral wall followed by its postsystolic shortening contributes to inefficient RV mechanics. However, a right-sided septal flash is a dichotomous finding, and the severity of RV dyssynchrony as a continuous spectrum in relationship to RV dysfunction and clinical outcomes in patients with repaired TOF has not been studied. The aim of this study was to quantify the severity of electromechanical dyssynchrony in relation to RV remodeling and clinical outcomes in a pediatric cohort following TOF repair.

METHODS

A retrospective analysis was performed in 81 children with RV volume loading after TOF repair, aged 13.6 ± 2.9 years, and compared with 50 matched control subjects.

RESULTS

Patients had higher RV basal-lateral prestretch and postsystolic strain amplitude and duration, RV mechanical dispersion, and basal lateral-septal wall delay compared with control subjects (P < .001 for all). All intra-RV dyssynchrony timing parameters were associated with reduced cardiac magnetic resonance-derived RV ejection fraction and/or echocardiography-derived RV longitudinal strain. Prestretch duration as a percentage of total shortening time and RV basal lateral-to-midseptal delay were independently associated with RV dysfunction. Postsystolic strain amplitude was higher in patients with ventricular arrhythmias compared with arrhythmia-free patients (7.8% [4.2%-13%] vs 2.0% [0%-12.5%], P = .03).

CONCLUSION

RV prestretch duration, postsystolic strain, and RV lateral-septal delay quantify RV electromechanical dyssynchrony severity and reflect the underlying pathophysiology. The prestretch duration percentage and RV basal lateral-to-midseptal delay were independently associated with RV dysfunction, potentially providing a clinical tool to quantify RV electromechanical dyssynchrony.

Review and status report of pediatric left ventricular systolic strain and strain rate nomograms

Interest in strain (ε) and strain rate (SR) for the assessment of pediatric left ventricular (LV) myocardial function has increased. However, the strengths and limitations of published pediatric nomograms have not been critically evaluated. A literature search was conducted accessing the National Library of Medicine using the keywords myocardial velocity, strain, strain rate, pediatric, reference values, and nomograms. Adding the following keywords, the results were further refined: neonates, infants, adolescents, range/intervals, and speckle tracking. Ten published studies evaluating myocardial velocities, ε, or SR nomograms were analyzed. Sample sizes were limited in most of these studies, particularly in terms of neonates. Heterogeneous methods-tissue Doppler imaging, two- and three-dimensional speckle tracking-were used to perform and normalize measurements. Although most studies adjusted measurements for age, classification by specific age subgroups varied. Few studies addressed the relationships of ε and SR measurements to body size and heart rate. Data have been generally expressed by mean values and standard deviations; Z scores and percentiles that are commonly employed for pediatric echocardiographic quantification have been never used. Reference values for ε and SR were found to be reproducible in older children; however, they varied significantly in neonates and infants. Pediatric nomograms for LV ε and SR are limited by (a) small sample sizes, (b) inconsistent methodology used for derivation and normalization, and (c) scarcity of neonatal data. Some of the studies demonstrate reproducible patterns for systolic deformation in older children. There is need for comprehensive nomograms of myocardial ε and SR involving a large population of normal children obtained using standardized methodology.

Influence of percutaneous atrial septal defect closure on inter- and intra-ventricular mechanical dyssynchrony in adults: evaluation of strain pattern

Previous studies using speckle-tracking echocardiography (STE) for quantifying the functions of the right and left ventricles (RV and LV, respectively) in the presence of percutaneous atrial septal defect (ASD) closure have focused on the peak systolic strain (PSS). This study investigated changes in the mechanical dyssynchrony of ventricular contraction before and after ASD closure, issues that have been little addressed in the literature. Thirty-one adults with ASD were studied using two-dimensional STE before and 24 h after ASD closure. Thirty-one healthy age- and sex-matched subjects were recruited as controls. Global and segmental PSS values from the longitudinal, circumferential, and radial directions were analyzed. The time to peak systolic strain (PSST) and the standard deviation of the time to peak strain (SDT) among segments in each direction were calculated, to investigate the inter- and intra-ventricular mechanical dyssynchrony in these patients and improvements after closure. Compared to the control group, patients with ASD had higher RV free-wall longitudinal systolic strain, with increased PSST and SDT. The SDT values of the LV longitudinal and circumferential strains were also increased. By 24 h after ASD closure, the RV free-wall longitudinal strain and its PSST and SDT had reverted to normal levels. The LV circumferential strain was increased, and its SDT was decreased. The contraction period of the RV and myocardial contraction dyssynchrony in the RV and LV were increased in ASD patients. The inter- and intra-ventricular mechanical utilities were improved after percutaneous closure of the ASD.

Reference intervals for the echocardiographic measurements of the right heart in children and adolescents: a systematic review

Background

Transthoracic echocardiography is the primary imaging modality for the diagnosis of right ventricular (RV) involvement in congenital and acquired heart diseases. There is increasing recognition of the contribution of RV dysfunction in heart diseases affecting children and adolescents, but there is insufficient information on reference intervals for the echocardiographic measurements of the right heart in children and adolescents that represent all the continental populations of the world.

Objective

The aim of this systematic review was to collate, from published studies, normative data for echocardiographic evaluation of the right heart in children and adolescents, and to identify gaps in knowledge in this field especially with respect to sub-Saharan Africans.

Methods

We performed a systematic literature search to identify studies of reference intervals for right heart measurements as determined by transthoracic echocardiography in healthy children and adolescents of school-going age. Articles were retrieved from electronic databases with a combination of search terms from the earliest date available until May 2013.

Results

Reference data were available for a broad range of variables. Fifty one studies out of 3096 publications were included. The sample sizes of the reference populations ranged from 13 to 2036 with ages varying from 5 to 21 years. We identified areas lacking sufficient reference data. These included reference data for determining right atrial size, tricuspid valve area, RV dimensions and areas, the RV % fractional area change, pulmonary artery pressure gradients and the right-sided haemodynamics, including the inferior vena cava dimensions and collapsibility. There were no data for sub-Saharan African children and adolescents.

Conclusion

Reliable reference data are lacking for important echocardiographic measurements of the RV in children and adolescents, especially for sub-Saharan Africans.

Relation of right ventricular mechanics to exercise tolerance in children after tetralogy of Fallot repair

BACKGROUND

Progressive right ventricular (RV) dysfunction and exercise intolerance are common problems after tetralogy of Fallot (TOF) repair. We investigated RV myocardial deformation and dyssynchrony in children after TOF repair and their association with exercise capacity.

METHODS

Asymptomatic children after TOF repair were investigated by 2-dimensional speckle tracking echocardiography, magnetic resonance, and metabolic exercise study. Patients with RV outflow obstruction were excluded. Peak RV longitudinal strain and strain rate (SR) and dyssynchrony (RV intraventricular delay) were compared with healthy controls. Associations between RV strain, dyssynchrony, and exercise capacity were analyzed.

RESULTS

Thirty-nine (81%) of 48 TOF patients and 40 healthy controls had adequate RV strain imaging. The TOF patients had moderately dilated RVs and normal RV ejection fraction. Right ventricular peak systolic strain (-23.2% ± 5.1% vs -28.5% ± 8.5%, P < .001) and SR (-1.46 ± 0.68 vs -2.1 ± 0.8, P < .001) were reduced in TOF patients compared with controls. Right ventricular intraventricular delay was higher in TOF patients (146.0 ± 159 vs 71.0 ± 92 milliseconds, P = .008). Decreased RV strain and SR were associated with increased RV dyssynchrony (strain parameter estimate [PE] 6.31 [2.30], P = .007; SR [PE] 11.32 [3.84], P = .004). Increased RV-left ventricular delay was associated with prolonged QRS duration (PE 0.13 [0.058], P = .03) and reduced RV ejection fraction (PE -2.95 [1.275], P = .02). Reduced RV peak SR was associated with decreased exercise peak oxygen uptake (PE 0.14 [0.07], P = .04).

CONCLUSIONS

After repair of TOF, asymptomatic children have reduced RV deformation in association with RV dyssynchrony and reduced exercise tolerance.

Transthoracic echocardiography in children and young adults with congenital heart disease

Transthoracic echocardiography (TTE) is the first-line tool for diagnosis and followup of pediatric and young adult patients with congenital heart disease (CHD). Appropriate use of TTE can reduce the need for more invasive modalities, such as cardiac catheterization and cardiac magnetic resonance imaging. New echocardiographic techniques have emerged more recently: tissue Doppler imaging, tissue tracking (strain and strain rate), vector velocity imaging (VVI), myocardial performance index, myocardial acceleration during isovolumic acceleration (IVA), the ratio of systolic to diastolic duration (S/D ratio), and two dimensional measurements of systolic right ventricular (RV) function (e.g., tricuspid annular plane systolic excursion, TAPSE). These may become valuable indicators of ventricular performance, compliance, and disease progression. In addition, three-dimensional (3D) echocardiography when performed for the assessment of valvular function, device position, and ventricular volumes is being integrated into routine clinical care. In this paper, the potential use and limitations of these new echocardiographic techniques in patients with CHD are discussed. A particular focus is on the echocardiographic assessment of right ventricular (RV) function in conditions associated with increased right ventricular volume (e.g., pulmonary regurgitation after tetralogy of Fallot repair) or pressure (e.g., pulmonary hypertension) in children and young adults.

Multimodality Imaging in Congenital Heart Disease: an Update

The increasing number of survivors of congenital heart disease (CHD) has been paralleled by advancement of imaging modalities used for the ongoing assessment of these patients. There has been a large body of literature describing new approaches to non-invasive assessment of CHD. We will review new applications of well established as well as novel techniques for the management and understanding of CHD.

Non-Invasive Imaging for Congenital Heart Disease: Recent Innovations in Transthoracic Echocardiography

Transthoracic echocardiography (TTE) is an important tool for diagnosis and follow-up of patients with congenital heart disease (CHD). Appropriate use of TTE can reduce the need for more invasive and complex modalities, such as cardiac catheterization and cardiac magnetic resonance imaging. New echocardiographic techniques have emerged for the assessment of ventricular systolic and diastolic function: Tissue Doppler imaging, tissue tracking, strain and strain rate imaging, vector velocity imaging (VVI), myocardial performance index, myocardial acceleration during isovolumic contraction (IVA), the ratio of systolic to diastolic duration (S/D ratio), and other measurements of systolic right ventricular (RV) function like tricuspid annular plane systolic excursion (TAPSE). These modalities may become valuable indicators of ventricular performance, compliance and disease progression, with the caveat of preload-dependency of the variables measured. In addition, three-dimensional (3D) echocardiography for the assessment of cardiac anatomy, valvular function, device position, ventricular volumes and ejection fraction is integrated into routine clinical care. In this review, we discuss the potential use and limitations of these new echocardiographic techniques in patients with CHD. A particular focus is on the echocardiographic assessment of right ventricular (RV) function by means of tissue Doppler imaging, tissue tracking, and three-dimensional imaging, in conditions associated with increased right ventricular volume or pressure load.