Faculty Bibliography

This study aimed to determine whether quantification of subpulmonary stenosis (SPS) in tetralogy of Fallot (TOF) in the second-trimester fetus can predict postnatal clinical outcome measured by pulmonary valve size and/or timing or type of intervention. The study retrospectively identified fetuses with TOF from 1998 to 2010 diagnosed at 26 weeks gestation or earlier. The data evaluated included pre- and postnatal pulmonary valve z-scores (PVZ). To quantify fetal SPS, the authors created a novel index, the SPS/DAO ratio, a ratio of the minimum infundibular diameter to the descending aorta diameter (DAO). Multiple linear regression was used to predict postnatal PVZ from prenatally determined parameters, including SPS/DAO. Fetal parameters were analyzed by logistic regression for association with postnatal outcomes, namely, timing of surgery (<1 month), used as a surrogate for severity, and type of surgery [transannular patch (TAP) vs valve sparing surgery]. A total of 23 fetuses met the inclusion criteria. The mean gestational age was 21.8 +/- 1.9 weeks (range, 16.6-25.4 weeks). There was excellent correlation between predicted and measured PVZ (r = 0.82; p < 0.0001) using the following derived equation: -3.68 + (0.91 x prenatal PVZ) - (4.44 x SPS/DAO) - 3.19 (prenatal PVZ x SPS/DAO). An SPS/DAO value lower than 0.5 had 100 % sensitivity and 56 % specificity for repair before the age of 1 month, and a value lower than 0.47 had 100 % sensitivity and 75 % specificity for TAP repair. Prenatal PVZ and the SPS/DAO ratio at 26 weeks gestation or earlier can reliably predict postnatal PVZ in fetuses with TOF. Quantification of SPS with the SPS/DAO ratio identifies patients who may require early intervention secondary to disease severity and may predict the type of repair, thereby influencing prenatal counseling.

Thoracic aortic disease is a known cause of aortic dilatation and poses significant risk of aortic dissection and rupture. Serial assessment of aortic root dimensions is traditionally performed using echocardiography, which is limited with older age and following surgery, due to poor acoustic windows. Although diastolic measurements are utilized as standard practice in decision making of adult aortopathy, systolic diameters are utilized in pediatric practice. Three-dimensional steady-state free precision (3D-SSFP) has shown promise as an alternate method for providing accurate and reproducible aortic measurements. The agreement between proximal aorta measurements by diastolic 3D-SSFP and echocardiography (both systole and diastole) was examined in 40 subjects. The maximum inner diameters at aortic annulus, root and sinotubular junction demonstrated excellent agreement between 3D-SSFP and echocardiography for all the 3 levels. The best agreement was observed for diastolic root dimensions with a mean difference of +0.01 cm, limits of agreement being -0.26 to +0.28 cm. Three D-SSFP can be used interchangeably with echocardiography in the serial assessment of the aortic root size. Careful attention to obtain an imaging plane utilizing 3D multiplanar reformatting is critical to maximize the agreement between the two imaging modalities.

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.

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.

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.

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: 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.

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.

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