Andreea Dragulescu

Echocardiographic Assessment of Right Ventricular Volumes after Surgical Repair of Tetralogy of Fallot: Clinical Validation of a New Echocardiographic Method

BACKGROUND Assessment of right ventricular (RV) volumes and function is important in patients after tetralogy of Fallot (TOF) repair. Currently, cardiac magnetic resonance imaging (MRI) is considered the clinical reference method for RV volume and function measurements. Three-dimensional (3D) knowledge-based reconstruction derived from two-dimensional echocardiographic imaging with magnetic tracking is a novel approach to RV volumetrics. The aim of this study was to assess the feasibility and reliability of this novel echocardiographic technique in patients after TOF repair. The accuracy of the method was assessed by comparison with measurements obtained by cardiac MRI. METHODS Thirty patients (mean age, 13.7 ± 2.8 years) after TOF repair, referred for cardiac MRI, were included. Immediately after MRI, echocardiographic image acquisition was performed using a standard ultrasound scanner linked to a Ventripoint Medical Systems unit. Echocardiographic and MRI measurements were performed offline. Parameters analyzed were end-diastolic volume (EDV), end-systolic volume (ESV), and ejection fraction. Intraobserver, interobserver, and intertechnique variability was assessed using Pearsons correlation analysis, coefficients of variation, and Bland-Altman analysis. RESULTS Echocardiographic two-dimensionally based 3D reconstruction was highly feasible, with low intraobserver and interobserver variability for EDV and slightly higher variability for ESV and ejection fraction. The 3D reconstruction values for EDV, ESV, and ejection fraction were correlated highly with MRI values, with low coefficients of variation. The agreement between both methods was high. Three-dimensional reconstruction slightly underestimated RV volumes, by 2.5% for EDV and 4.6% for ESV compared with MRI volumes. CONCLUSIONS In patients after TOF repair, echocardiographic 3D reconstruction is highly feasible, with good reproducibility for measurements of RV EDV. There is good agreement with MRI measurements, with a small underestimation of RV volumes. The use of this method in clinical practice warrants further investigation.

Interpretation of Left Ventricular Diastolic Dysfunction in Children With Cardiomyopathy by Echocardiography Problems and Limitations

Background— Left ventricular diastolic dysfunction (DD) is a key determinant of outcomes in pediatric cardiomyopathy (CM), but remains very challenging to diagnose and classify. Adult paradigms and guidelines relating to DD are currently applied in children. However, it is unknown whether these are applicable to children with CM. We investigated the assessment of DD in children with CM using adult and pediatric echocardiographic criteria and tested whether recent adult guidelines are applicable to this population. Methods and Results— Three investigators independently classified diastolic function in 4 study groups: controls, dilated, hypertrophic, and restrictive CM. Agreement among investigators, failure to classify DD, and the reasons for diagnostic failure were determined. The usefulness of individual echo parameters to diagnose and classify DD was assessed. One hundred seventy-five children (aged 0–18 years) were studied. DD diagnostic criteria were discrepant in the majority of patients. Delayed relaxation was diagnosed in only 14% of hypertrophic CM patients and never in dilated CM and restrictive CM, with 50% of those patients having coexisting findings of elevated filling pressures. Many key parameters, such as mitral and pulmonary venous Doppler, were not informative. Agreement among investigators for grading of DD was poor (36% of CM patients). Conclusions— Assessment of DD in childhood CM seems inadequate using current guidelines. The large range of normal pediatric reference values allows diagnosis of DD in only a small proportion of patients. Key echo parameters to assess DF are not sufficiently discriminatory in this population, and discrepancies between criteria within individuals prevent further classification and result in poor interobserver agreement.

Developments in echocardiographic techniques for the evaluation of ventricular function in children

Echocardiography is a very important tool for the diagnosis and follow-up of children with congenital and acquired heart disease. One of the challenges that remains in paediatric heart disease is the assessment of systolic and diastolic function in children, as this is influenced by growth, morphology and loading conditions. New echocardiographic techniques, such as tissue Doppler, deformation imaging and three-dimensional echocardiography, have great potential application in this field. They may provide new insights into the influence of growth, morphology and loading on cardiac mechanics, and could become useful clinical tools. In this review, we discuss the potential use and limitations of these new echocardiographic techniques in paediatric and congenital heart disease.

Differential effect of right ventricular dilatation on myocardial deformation in patients with atrial septal defects and patients after tetralogy of Fallot repair

BACKGROUND Right ventricular (RV) volume overload results in RV dilatation in patients with atrial septal defect (ASD) and after tetralogy of Fallot (ToF) repair with pulmonary regurgitation. AIM Study the differential effects of chronic RV volume loading on regional and global RV deformation in patients with ASD and after TOF repair. METHODS We studied 85 subjects: 50 patients after ToF repair, 15 patients with unrepaired ASD and 20 age-matched controls. The ToF patients and controls underwent an echocardiography at the time of a clinically indicated MRI. The ASD patients had a routine echocardiogram including RV volume calculations. Longitudinal deformation was analyzed using 2-D speckle tracking echocardiography. RESULTS RV free wall global and segmental longitudinal deformation was significantly lower in ToF patients compared with ASD and controls (p<0.001). In ToF patients, there was a progressive decrease in strain values from base to apex (p<0.001), while in the ASD group there was a progressive increase (p=0.04). We found strong negative correlations between RV size and RV longitudinal strain measurements, strongest with RV length (R=0.72). When corrected for RV size, all ASD patients had normal or higher deformation values while half of the TOF patients had significantly lower values. CONCLUSION Global and regional myocardial RV deformation is differently affected by chronic volume loading in ASD versus TOF patients, especially regarding the apical function. This suggests a different adaptation mechanism in both diseases. Our data also suggest that strain measurements are strongly influenced by ventricular size, which should be taken into consideration when interpreting strain values.

Reference Values for Pulse Wave Doppler and Tissue Doppler Imaging in Pediatric Echocardiography

Background—In pediatric echocardiography, pulse wave Doppler, and tissue Doppler imaging velocities are widely used to assess cardiac function. Current reference values and Z scores, allowing adjustment for growth are limited by inconsistent methodologies and small sample size. Using a standardized approach for parametric modeling and Z score quality assessment, we propose new pediatric reference values and Z score equations for most left ventricular pulse wave Doppler and tissue Doppler imaging measurements. Methods and Results—Two hundred thirty-three healthy pediatric subjects 1 to 18 years of age were prospectively recruited. Thirteen pulse wave Doppler and 14 tissue Doppler imaging measurements were recorded. Normalization for growth was done via a complete and standardized approach for parametric nonlinear regression modeling. Several analyses were performed to ensure adequate Z score distribution and to detect potential residual associations with growth or residual heteroscedasticity. Most measurements adopted a nonlinear relationship with growth and displayed significant heteroscedasticity. Compared with age, height, and weight, normalization for body surface area was most efficient in removing the effect of growth. Generally, polynomial and allometric models yielded adequate goodness-of-fit. Residual values for several measurements had significant departure from the normal distribution, which could be corrected using logarithmic or reciprocal transformation. Overall, weighted parametric nonlinear models allowed us to compute Z score equations with adequate normal distribution and without residual association with growth. Conclusions—We present Z scores for normalized pulse wave Doppler and tissue Doppler imaging in pediatric echocardiography. Further studies are needed to define the threshold beyond which health becomes a disease by integrating other important factors such as ventricular morphology, loading conditions, and heart rate.

Effect of Chronic Right Ventricular Volume Overload on Ventricular Interaction in Patients after Tetralogy of Fallot Repair

BACKGROUND Right ventricular (RV) volume overload results in RV dilatation and dysfunction in patients with pulmonary regurgitation after tetralogy of Fallot (ToF) repair, affecting left ventricular (LV) function because of ventricular interaction. The aim of this study was to assess the effect of chronic RV volume loading on LV myocardial mechanics in patients after ToF repair by combining cardiac magnetic resonance imaging with echocardiography. METHODS Seventy-five subjects were studied: 50 patients after ToF repair and 25 age-matched controls. All patients with ToF and controls underwent echocardiography at the time of clinically indicated cardiac magnetic resonance imaging. Myocardial deformation, including LV torsion, was analyzed using speckle-tracking echocardiography. RESULTS RV free wall global and segmental longitudinal strain and strain rate were significantly lower in patients with ToF compared with controls (P < .001). All LV longitudinal, strain, and torsion parameters were significantly reduced in patients with ToF (P < .01). Basal rotation was particularly abnormal, with 38% of patients with ToF having reversed basal rotation. In contrast, apical rotation was reduced but not reversed. On multivariate regression analysis, the only significant predictor of counterclockwise basal rotation was RV strain, suggesting that RV function more than dilatation influences abnormal LV torsion. CONCLUSION Patients with ToF have abnormal LV myocardial mechanics, as demonstrated by speckle-tracking echocardiography. The most striking changes were noted in LV torsion, especially related to abnormal LV basal rotation. RV dysfunction seems the most important determinant of abnormal LV rotation. The clinical significance and potential prognostic implications of these observations remain to be determined.

Right ventricular diastolic performance in children with pulmonary arterial hypertension associated with congenital heart disease: correlation of echocardiographic parameters with invasive reference standards by high-fidelity micromanometer catheter.

Background—Right ventricular diastolic dysfunction influences outcomes in pulmonary arterial hypertension (PAH), but echocardiographic parameters have not been investigated in relation to invasive reference standards in pediatric PAH. We investigated echocardiographic parameters of right ventricular diastolic function in children with PAH in relation to simultaneously measured invasive reference measures. Methods and Results—We prospectively recruited children undergoing a clinically indicated cardiac catheterization for evaluation of PAH and pulmonary vasoreactivity testing. Echocardiography was performed simultaneously with invasive reference measurements by high-fidelity micromanometer catheter. For analysis, patients were divided into shunt and nonshunt groups. Sixteen children were studied. In the group as a whole, significant correlations were found among &tgr; and tricuspid deceleration time, E′, E/E′, TimeE–E′, A wave velocity, and global early and late diastolic strain rate. dp/dt minimum correlated significantly with late diastolic tricuspid annular velocity (A′), tissue Doppler imaging–derived systolic:diastolic duration ratio, and global late diastolic strain rate. End-diastolic pressure correlated significantly with tissue Doppler imaging–derived systolic:diastolic duration ratio. On multivariate analysis, tricuspid deceleration time, TimeE–E′, and global early diastolic strain rate were independent predictors of &tgr;, whereas tissue Doppler imaging–derived systolic:diastolic duration ratio was an independent predictor of dp/dt minimum. In general, correlations between echocardiographic and invasive parameters were better in the shunt group than in the nonshunt group. Conclusions—Echocardiography correlates with invasive reference measures of right ventricular diastolic function in children with PAH, although it does not differentiate between early versus late diastolic abnormalities. Newer echocardiographic techniques may have added value to assess right ventricular diastolic dysfunction in this population.

Mechanisms of Right Ventricular Electromechanical Dyssynchrony and Mechanical Inefficiency in Children After Repair of Tetralogy of Fallot

Background—Right bundle branch block and right ventricular (RV) dysfunction are common after tetralogy of Fallot repair (rTOF). We hypothesized that right bundle branch block is associated with specific RV mechanical dyssynchrony and inefficient contraction. Methods and Results—We studied rTOF children and age-matched controls. QRS duration and morphology were assessed. RV mechanical dyssynchrony, indicated by early septal activation (right-sided septal flash), RV lateral wall prestretch/late contraction, postsystolic shortening, and intraventricular delay were analyzed using 2-dimensional strain echocardiography. Peak oxygen consumption reflected exercise capacity. Pulmonary regurgitation and RV volumes were assessed by MRI. Forty-six rTOF patients and 46 controls were studied. Ninety-three percent of rTOF patients demonstrated a right-sided septal flash with simultaneous RV basal lateral wall prestretch/late activation. The RV basal segment was the most delayed in onset (115 [0–194] versus 35 [0–96] ms) and termination (462 [369–706] versus 412 [325–529] ms) of longitudinal shortening, with postsystolic shortening. QRS duration correlated with RV basal time to onset and peak shortening (P<0.05). Intra-RV delay was higher in rTOF (P<0.05) in association with RV dilatation (r=0.33; P=0.04). In rTOF, RV mechanics were inefficient, with prestretch and postsystolic shortening comprising 15±11% and 16±9% of total shortening, respectively. A composite parameter of electric and mechanical dyssynchrony correlated with RV end-diastolic volume (r=0.39; P=0.03). Conclusions—Typical electromechanical dyssynchrony associated with mechanical inefficiency, regional dysfunction, and RV dilatation is common in rTOF children, possibly contributing to progressive RV dysfunction. The potential of cardiac resynchronization in appropriate patients requires further study.

Paclitaxel drug-eluting stent placement for pulmonary vein stenosis as a bridge to heart-lung transplantation.

Congenital pulmonary vein stenosis (PVS) presents as an isolated lesion or in association with other congenital heart anomalies. The most extensive forms of the disease are uniformly fatal because neither surgical repair nor transcatheter therapy results in long-term relief of the stenosis. A case is presented involving single-ventricle physiology associated with extensive and recurrent congenital PVS despite multiple attempts with surgical therapy. Heart–lung transplantation was ultimately performed after drug-eluting stents were placed in pulmonary veins as a bridge to the transplantation.

Utility of Contrast Echocardiography for Pulmonary Arteriovenous Malformation Screening in Pediatric Hereditary Hemorrhagic Telangiectasia

OBJECTIVE To evaluate the utility of transthoracic contrast echocardiography (TTCE) as a screening tool for pulmonary arteriovenous malformations (PAVMs) in children with hereditary hemorrhagic telangiectasia (HHT). STUDY DESIGN This was a single-center study of children who underwent baseline screening for PAVMs using both TTCE and chest computed tomography (CT) for evaluation of HHT. The CT and TTCE results were prospectively reviewed independently by 2 radiologists and 2 cardiologists blinded to the study results. RESULTS Both intraobserver and interobserver agreement for interpreting TTCE results were excellent (κ = 0.97 and 0.92, respectively) and higher than the interobserver agreement for CT interpretation (κ = 0.75). The sensitivity and specificity of TTCE to predict PAVMs were 1 and 0.82, respectively, and the positive predictive and negative predictive values were 0.39 and 1, respectively. CONCLUSION TTCE is a sensitive test for PAVMs in children with suspected HHT and can be a useful initial screening tool in pediatric HHT.