Faculty Bibliography

BACKGROUND: Decreased right ventricular (RV) ejection fraction (EF) increases morbidity in repaired tetralogy of Fallot (rToF). Cardiac magnetic resonance (CMR) is the accepted reference standard for RV EF measurement. There are no established color Doppler tissue imaging (cDTI) values that identify decreased RV EF in rToF. We sought to assess accuracy of cDTI myocardial deformation and velocity indices in predicting CMR-derived RV EF. METHODS: Retrospective evaluation of CMR and echocardiography studies performed on the same day. cDTI-derived peak systolic velocity (pkS), isovolumic acceleration (IVA) of the tricuspid valve annulus, strain (epsilon) and strain rate (SR) of the RV free wall, adjusted for age, volume and pressure overload were used to compute RV EF. The probability of correctly classifying CMR measured RV EF <45% was estimated by logistic regression analysis. The accuracy of the model was tested on 10 prospective patients. RESULTS: Sixty matched echocardiographic and CMR studies were analyzed. None of the individual cDTI parameters could reliably identify patients with CMR-derived decreased RV EF. However, when adjusted for age in a logistic model: Y = -0.5 - 0.07 x age + 0.016 x epsilon + 0.46 x pkS, where Y is the logit (log odds), patients with RV EF <45% were identified with 86% sensitivity, 93.5% specificity. Prospective application of this model correctly identified all subjects with RV EF <45%. CONCLUSION: The age-adjusted logistic model and not individual parameters, derived from cDTI-derived pkS, and epsilon can reliably identify patients with decreased RV EF <45%.

BACKGROUND: Left atrial volume (LAV) increase is an indicator of diastolic dysfunction and a surrogate marker of significant left to right shunts. Normalization of LAV is currently performed by indexing to body surface area(1) (BSA(1)). The indexed LAV thus derived does not account for the nonlinear relationship of physiologic variables to BSA and has not been tested for independence to body size. Our objective was to identify a valid allometric model for indexing LAV and use it to develop Z-scores in children. METHODS AND RESULTS: LAV was measured in 300 normal subjects by echocardiography using the biplane area length method. LAV/BSA(1) had a residual relationship to BSA (r=0.52, P<0.0001). The allometric exponent (AE) derived for the entire cohort (1.27) using the least squares regression analysis also failed to eliminate the residual relationship to BSA (r=-0.15, P=0.01). Dividing the cohort in two groups with a BSA cut-off of 1 m(2) provided the best-fit allometric model. The AE for each group was 1.48 and 1.08 for BSA1 m(2), respectively, and was validated against an independent sample. The mean indexed LAV+/-SD for BSA1 m(2) is 31.5+/-5.5 mL and 26.0+/-4.2 mL, respectively, and was used to derive Z-scores. CONCLUSIONS: This study demonstrates the fallacy of using "per-BSA(1) standards" for normalization of LAV in pediatrics. LAV/BSA(1.48) for children with BSA1 m(2) is accurate and can be used to derive Z-scores.

Imaging of the coronary arteries is an important part of the evaluation of children with congenital heart disease and isolated congenital coronary artery anomalies. Echocardiography remains the main imaging modality and is complemented by MRI and CT angiography in the older or difficult-to-image child. We review echocardiography, MRI, and CT angiography for coronary artery imaging, with emphasis on techniques. The clinical implications of isolated congenital coronary artery anomalies are also addressed, along with a discussion about the current consensus on optimal management of these anomalies.

The hemodynamics of isolated large ventricular septal defect with an intact atrial septum results in greater mitral valve (MV) annular dilation and an increased incidence of mitral regurgitation (MR). MR will resolve in most patients after surgical VSD closure alone without MV repair.

A published formula containing minimal aortic cross-sectional area and the flow deceleration pattern in the descending aorta obtained by cardiovascular magnetic resonance predicts significant coarctation of the aorta (CoA). However, the existing formula is complicated to use in clinical practice and has not been externally validated. Consequently, its clinical utility has been limited. The aim of this study was to derive a simple and clinically practical algorithm to predict severe CoA from data obtained by cardiovascular magnetic resonance. Seventy-nine consecutive patients who underwent cardiovascular magnetic resonance and cardiac catheterization for the evaluation of native or recurrent CoA at Children's Hospital Boston (n = 30) and the University of California, San Francisco (n = 49), were retrospectively reviewed. The published formula derived from data obtained at Children's Hospital Boston was first validated from data obtained at the University of California, San Francisco. Next, pooled data from the 2 institutions were analyzed, and a refined model was created using logistic regression methods. Finally, recursive partitioning was used to develop a clinically practical prediction tree to predict transcatheter systolic pressure gradient >/= 20 mm Hg. Severe CoA was present in 48 patients (61%). Indexed minimal aortic cross-sectional area and heart rate-corrected flow deceleration time in the descending aorta were independent predictors of CoA gradient >/= 20 mm Hg (p <0.01 for both). A prediction tree combining these variables reached a sensitivity and specificity of 90% and 76%, respectively. In conclusion, the presented prediction tree on the basis of cutoff values is easy to use and may help guide the management of patients investigated for CoA.

BACKGROUND: The measurement error for right ventricular (RV) size and function assessed by cardiac MRI (CMRI) in congenital heart disease has not been fully characterized. As CMRI parameters are being increasingly utilized to make clinical decisions, defining error in the clinical setting is critical. OBJECTIVE: This investigation examines the repeatability of CMRI for RV size and function. MATERIALS AND METHODS: Forty consecutive people with congenital heart disease involving the RV were retrospectively identified. Contouring of RV volumes was performed by two expert CMRI clinicians. The coefficient of variability and repeatability coefficients were calculated. Repeatability coefficients were multiplied by the mean value for each group studied to define a threshold beyond which measurement error was unlikely to be responsible. RESULTS: The variability for indexed RV end-diastolic volume = 3.2% and 3.3% for intra- and interobserver comparisons, respectively. The repeatability coefficients were 13.2% and 14.9% for intra- and interobserver comparisons, which yielded threshold values of 15.1 ml/m^2 and 20.2 ml/m^2, respectively. For RV ejection fraction (EF), the repeatability coefficients for intra- and interobserver comparisons were 5.0% and 6.0%, which resulted in threshold values of 2.6 EF% and 3.0 EF%. CONCLUSION: The threshold values generated can be used during serial assessment of RV size and function.

Restrictive cardiomyopathy (RCM) is characterized by irreversible diastolic dysfunction with preserved systolic function. The aim of this study was to investigate the presence of impaired ventricular contractility even in the presence of normal ejection fraction (EF) in children with RCM. Longitudinal Doppler tissue velocities were obtained from apical 4-chamber view at three locations--the left-ventricular (LV) lateral wall, the septum, and the right ventricle--in 8 children age 3-17 years old with RCM who had LV EF >55%. Peak systolic velocity (S'), acceleration during isovolumic contraction (IVA), and myocardial performance index (MPI) were measured. Data from the RCM group were compared with those from 24 age- and sex-matched controls. Both S' and IVA were markedly lower at the septum (S' 6.2 +/- 1.7 vs. 9.2 +/- 1.6, P < 0.001; IVA 1.8 +/- 0.5 vs. 3.9 +/- 1.5, P < 0.001). MPI, a measure of both diastolic and systolic function, was statistically significantly greater in the RCM group at all 3 locations (P < 0.005). S' and IVA identify global subclinical systolic dysfunction in RCM with normal EF. These findings suggest that pre-ejection abnormality and subclinical systolic dysfunction coexist with diastolic dysfunction in children with RCM.

BACKGROUND: Left ventricular (LV) end-diastolic volume (LVEDV) can be estimated by the formula (5/6) x area x length, or the "bullet" method. The aim of this study was to determine the range of normal LVEDV values in infants and young children (aged 0-3 years) by the subxiphoid bullet method. METHODS: Echocardiograms from 100 normal subjects aged