Elif Seda Selamet Tierney

Endothelial Pulse Amplitude Testing: Feasibility and Reproducibility in Adolescents

OBJECTIVES To test prospectively the reproducibility and feasibility of endothelial pulse amplitude testing (Endo-PAT), a novel Food and Drug Administration-approved technology, in healthy adolescents. STUDY DESIGN We performed Endo-PAT testing on 2 different days separated by no more than 7 days in 30 healthy fasting adolescents, ages 13 to 19 years, to assess reproducibility and feasibility. The reported level of discomfort, as measured on a pain scale of 1 to 5, was documented. RESULTS The mean difference in paired Endo-PAT indices was 0.12 (95% CI, -0.09-0.33; P = .24; intraclass correlation coefficient, 0.78), and the within-subject variation of Endo-PAT index was 0.16. The Endo-PAT index on test days 1 and 2 were 1.91 +/- 0.57 and 1.78 +/- 0.51 (mean plus or minus SD), respectively. All attempted studies (100%) were completed (95% CI, 88%-100%), and all completed studies (100%) could be analyzed (95% CI, 88%-100%). The median pain score was 1 on both days. CONCLUSION In healthy adolescents, Endo-PAT is feasible and has excellent reproducibility. This technology may provide an easy and reliable means of assessing endothelial function in the pediatric population.

The ventricular volume variability study of the Pediatric Heart Network: study design and impact of beat averaging and variable type on the reproducibility of echocardiographic measurements in children with chronic dilated cardiomyopathy.

BACKGROUND Clinical trials often rely on echocardiographic measures of left ventricular size and function as surrogate end points. However, the quantitative impact of factors that affect the reproducibility of these measures is unknown. To address this issue, the National Heart, Lung, and Blood Institute-funded Pediatric Heart Network designed a longitudinal observational study of children with known or suspected dilated cardiomyopathy aged 0 to 22 years from eight pediatric clinical centers. METHODS Clinical data were collected together with 150 echocardiographic indices of left ventricular size and function. Separate observers performed duplicate echocardiographic imaging. Multiple observers performed measurements from three cardiac cycles to enable assessment of intraobserver and interobserver variability. The impacts of beat averaging (BA), observer type (local vs core), and variable type (areas, calculations, dimensions, slopes, time intervals, and velocities) on measurement reproducibility were studied. The outcome measure was percentage error (100 × difference/mean). RESULTS Of 173 enrolled subjects, 131 met criteria for dilated cardiomyopathy. BA, variable type and observer type all influenced percentage error (P < .0001). Core interobserver percentage error (medians, 11.4%, 10.2%, and 9.3% for BA using one, two, and three beats, respectively) was approximately twice the intraobserver percentage error (medians, 6.3%, 4.9%, and 4.2% for BA using one, two, and three beats, respectively). Slopes and calculated variables exhibited high percentage error despite BA. Chamber dimensions, areas, velocities, and time intervals exhibited low percentage error. CONCLUSIONS This comprehensive evaluation of quantitative echocardiographic methods will provide a valuable resource for the design of future pediatric studies. BA and a single core lab observer improve the reproducibility of echocardiographic measurements in children with dilated cardiomyopathy. Certain measurements are highly reproducible, while others, despite BA, are poorly reproducible.

Mitral valve replacement in infants and children 5 years of age or younger: evolution in practice and outcome over three decades with a focus on supra-annular prosthesis implantation.

OBJECTIVE Successful mitral valve replacement in young children is limited by the lack of small prosthetic valves. Supra-annular prosthesis implantation can facilitate mitral valve replacement with a larger prosthesis in children with a small annulus, but little is known about its effect on the outcomes of mitral valve replacement in young children. METHODS One hundred eighteen children underwent mitral valve replacement at 5 years of age or younger from 1976-2006. Mitral valve replacement was supra-annular in 37 (32%) patients. RESULTS Survival was 74% +/- 4% at 1 year and 56% +/- 5% at 10 years but improved over time (10-year survival of 83% +/- 7% from 1994-2006). Factors associated with worse survival included earlier mitral valve replacement date, age less than 1 year, complete atrioventricular canal, and additional procedures at mitral valve replacement, but not supra-annular mitral valve replacement. As survival improved during our more recent experience, the risks of supra-annular mitral valve replacement became apparent; survival was worse among patients with a supra-annular prosthesis after 1991. A pacemaker was placed in 18 (15%) patients within 1 month of mitral valve replacement and was less likely in patients who had undergone supra-annular mitral valve replacement. Among early survivors, freedom from redo mitral valve replacement was 72% +/- 5% at 5 years and 45% +/- 7% at 10 years. Twenty-one patients with a supra-annular prosthesis underwent redo mitral valve replacement. The second prosthesis was annular in 15 of these patients and upsized in all but 1, but 5 required pacemaker placement for heart block. CONCLUSIONS Supra-annular mitral valve replacement was associated with worse survival than annular mitral valve replacement in our recent experience. Patients with supra-annular mitral valve replacement were less likely to have operative complete heart block but remained at risk when the prosthesis was subsequently replaced.

Ventricular Function Deteriorates With Recurrent Coarctation in Hypoplastic Left Heart Syndrome

BACKGROUND Recurrent coarctation (re-CoA) after stage I palliation in hypoplastic left heart syndrome (HLHS) is deleterious. We studied whether re-CoA had an effect on ventricular systolic function. METHODS Retrospectively reviewed were HLHS patients surviving stage I Norwood palliation (stage I) and cavopulmonary shunt (CPS) between January 2004 and February 2007. Echocardiographic right ventricular fractional area change (RV-FAC) was used to evaluate ventricular systolic function after stage I, before CPS, and before Fontan procedures. Cardiac catheterization and magnetic resonance imaging data before CPS were reviewed to assess re-CoA, using a coarctation index (CI = isthmus diameter/descending aortic diameter). RESULTS Fifty-one patients were included, and 21 had a CI of less than 0.75 (mean, 0.82 +/- 0.19; 21). Twelve patients required arch balloon dilation between CPS and Fontan. The change of RV-FAC for all patients between stage I and CPS was -2.2% +/- 9.6%. Pearson correlation coefficient demonstrated a significant correlation between lower CI values and lower RV-FAC at the pre-CPS echocardiogram (r = .35, p = 0.03); and lower CI values and greater decrease in RV-FAC between stage I and pre-CPS evaluation (r = 0.40, p = 0.018). At follow-up pre-Fontan, RV-FAC for patients who underwent balloon dilation for re-CoA recovered to a level that was inferior but not significantly different from that of patients who did not need balloon dilation. CONCLUSIONS Recurrent aortic arch obstruction after stage I for HLHS is associated with worse RV systolic function at the time of stage II operation. Timely intervention on the re-CoA results in recovery of RV function.

Characteristics of children and young adults with Marfan syndrome and aortic root dilation in a randomized trial comparing atenolol and losartan therapy

BACKGROUND The Pediatric Heart Network designed a clinical trial to compare aortic root growth and other short-term cardiovascular outcomes in children and young adults with Marfan syndrome randomized to receive atenolol or losartan. We report here the characteristics of the screened population and enrolled subjects. METHODS AND RESULTS Between 2007 and 2011, 21 clinical sites randomized 608 subjects, aged 6 months to 25 years who met the original Ghent criteria and had a body surface area-adjusted aortic root diameter z-score >3.0. The mean age at study entry was 11.2 years, 60% were male, and 25% were older teenagers and young adults. The median aortic root diameter z-score was 4.0. Aortic root diameter z-score did not vary with age. Mitral valve prolapse and mitral regurgitation were more common in females. Among those with a positive family history, 56% had a family member with aortic surgery, and 32% had a family member with a history of aortic dissection. CONCLUSIONS Baseline demographic, clinical, and anthropometric characteristics of the randomized cohort are representative of patients in this population with moderate to severe aortic root dilation. The high percentage of young subjects with relatives who have had aortic dissection or surgery illustrates the need for more definitive therapy; we expect that the results of the study and the wealth of systematic data collected will make an important contribution to the management of individuals with Marfan syndrome.

Predictors of Disease Progression in Pediatric Dilated Cardiomyopathy

Background—Despite medical advances, children with dilated cardiomyopathy (DCM) remain at high risk of death or need for cardiac transplantation. We sought to identify predictors of disease progression in pediatric DCM. Methods and Results—The Pediatric Heart Network evaluated chronic DCM patients with prospective echocardiographic and clinical data collection during an 18-month follow-up. Inclusion criteria were age <22 years and DCM disease duration >2 months. Patients requiring intravenous inotropic/mechanical support or listed status 1A/1B for transplant were excluded. Disease progression was defined as an increase in transplant listing status, hospitalization for heart failure, intravenous inotropes, mechanical support, or death. Predictors of disease progression were identified using Cox proportional hazards modeling and classification and regression tree analysis. Of the 127 patients, 28 (22%) had disease progression during the 18-month follow-up. Multivariable analysis identified older age at diagnosis (hazard ratio=1.14 per year; P<0.001), larger left ventricular (LV) end-diastolic M-mode dimension z-score (hazard ratio=1.49; P<0.001), and lower septal peak systolic tissue Doppler velocity z-score (hazard ratio=0.81; P=0.01) as independent predictors of disease progression. Classification and regression tree analysis stratified patients at risk of disease progression with 89% sensitivity and 94% specificity based on LV end-diastolic M-mode dimension z-score ≥7.7, LV ejection fraction <39%, LV inflow propagation velocity (color M-mode) z-score <−0.28, and age at diagnosis ≥8.5 months. Conclusions—In children with chronic stable DCM, a combination of diagnosis after late infancy and echocardiographic parameters of larger LV size and systolic and diastolic function predicted disease progression. Clinical Trial Registration—URL: http://www.clinicaltrials.gov. Unique identifier: NCT00123071.

Echocardiographic Methods, Quality Review, and Measurement Accuracy in a Randomized Multicenter Clinical Trial of Marfan Syndrome

BACKGROUND The Pediatric Heart Network is conducting a large international randomized trial to compare aortic root growth and other cardiovascular outcomes in 608 subjects with Marfan syndrome randomized to receive atenolol or losartan for 3 years. The authors report here the echocardiographic methods and baseline echocardiographic characteristics of the randomized subjects, describe the interobserver agreement of aortic measurements, and identify factors influencing agreement. METHODS Individuals aged 6 months to 25 years who met the original Ghent criteria and had body surface area-adjusted maximum aortic root diameter (ROOTmax) Z scores > 3 were eligible for inclusion. The primary outcome measure for the trial is the change over time in ROOTmaxZ score. A detailed echocardiographic protocol was established and implemented across 22 centers, with an extensive training and quality review process. RESULTS Interobserver agreement for the aortic measurements was excellent, with intraclass correlation coefficients ranging from 0.921 to 0.989. Lower interobserver percentage error in ROOTmax measurements was independently associated (model R(2) = 0.15) with better image quality (P = .002) and later study reading date (P < .001). Echocardiographic characteristics of the randomized subjects did not differ by treatment arm. Subjects with ROOTmaxZ scores ≥ 4.5 (36%) were more likely to have mitral valve prolapse and dilation of the main pulmonary artery and left ventricle, but there were no differences in aortic regurgitation, aortic stiffness indices, mitral regurgitation, or left ventricular function compared with subjects with ROOTmaxZ scores < 4.5. CONCLUSIONS The echocardiographic methodology, training, and quality review process resulted in a robust evaluation of aortic root dimensions, with excellent reproducibility.

Outcomes and Predictors of Perinatal Mortality in Fetuses With Ebstein Anomaly or Tricuspid Valve Dysplasia in the Current Era A Multicenter Study

Background— Ebstein anomaly and tricuspid valve dysplasia are rare congenital tricuspid valve malformations associated with high perinatal mortality. The literature consists of small, single-center case series spanning several decades. We performed a multicenter study to assess the outcomes and factors associated with mortality after fetal diagnosis in the current era. Methods and Results— Fetuses diagnosed with Ebstein anomaly and tricuspid valve dysplasia from 2005 to 2011 were included from 23 centers. The primary outcome was perinatal mortality, defined as fetal demise or death before neonatal discharge. Of 243 fetuses diagnosed at a mean gestational age of 27±6 weeks, there were 11 lost to follow-up (5%), 15 terminations (6%), and 41 demises (17%). In the live-born cohort of 176 live-born patients, 56 (32%) died before discharge, yielding an overall perinatal mortality of 45%. Independent predictors of mortality at the time of diagnosis were gestational age <32 weeks (odds ratio, 8.6; 95% confidence interval, 3.5–21.0; P<0.001), tricuspid valve annulus diameter z-score (odds ratio, 1.3; 95% confidence interval, 1.1–1.5; P<0.001), pulmonary regurgitation (odds ratio, 2.9; 95% confidence interval, 1.4–6.2; P<0.001), and a pericardial effusion (odds ratio, 2.5; 95% confidence interval, 1.1–6.0; P=0.04). Nonsurvivors were more likely to have pulmonary regurgitation at any gestational age (61% versus 34%; P<0.001), and lower gestational age and weight at birth (35 versus 37 weeks; 2.5 versus 3.0 kg; both P<0.001). Conclusion— In this large, contemporary series of fetuses with Ebstein anomaly and tricuspid valve dysplasia, perinatal mortality remained high. Fetuses with pulmonary regurgitation, indicating circular shunt physiology, are a high-risk cohort and may benefit from more innovative therapeutic approaches to improve survival.

Mutations in ZIC3 and ACVR2B are a common cause of heterotaxy and associated cardiovascular anomalies.

BACKGROUND Heterotaxy syndrome is caused by left-right asymmetry disturbances and is associated with abnormal lateralisation of the abdominal and thoracic organs. The heart is frequently involved and the severity of the abnormality usually determines the outcome. METHODS We performed a direct sequence analysis of the coding sequence of genes including Zinc Finger Protein of the Cerebellum 3, Left-Right Determination Factor 2, Activin A Receptor Type IIB, and Cryptic in 47 patients with laterality defects and congenital cardiac disease. RESULTS Of the 47 patients, 31 (66%) had atrioventricular septal defects, 34 (72%) had abnormal systemic venous return, 25 (53%) had transposed or malposed great arteries, and 20 (43%) had pulmonary venous abnormalities. We identified two novel genetic changes in Zinc Finger Protein of the Cerebellum 3, and these variants were not present in 100 ethnically matched control samples. One previously reported missense mutation in Activin A Receptor Type IIB was identified in two unrelated subjects. The genetic changes identified in this study are all located in conserved regions and are predicted to affect protein function in left-right axis formation and cardiovascular development. CONCLUSIONS Mutations in Zinc Finger Protein of the Cerebellum 3 and Activin A Receptor Type IIB were identified in 4 of the 47 patients with heterotaxy syndrome for a yield of approximately 8.5%. Our results expand the mutation spectrum of monogenic heterotaxy syndrome with associated cardiac anomalies and suggest that there are other causes of heterotaxy yet to be identified.

Variants of the CFC1 gene in patients with laterality defects associated with congenital cardiac disease

OBJECTIVES This study was designed to assess the frequency and types of genetic variants in CFC1 in children with laterality disorders associated with cardiovascular involvement. BACKGROUND Laterality syndromes are estimated to comprise 3% of neonates with congenital cardiac disease. Genetic predisposition in some cases of laterality defects has been suggested by associated chromosomal anomalies and familial aggregation, often within consanguineous families, suggesting autosomal recessive inheritance. Mice with induced homozygous mutations in cfc1, and heterozygous CFC1 mutations in humans, have been associated with laterality defects. METHODS Direct sequence analysis of the coding sequence of CFC1 was performed in 42 subjects with laterality defects and congenital cardiac disease. RESULTS We identified 3 synonymous coding variants, 3 non-synonymous coding variants (N21H, R47Q, and R78W), and 2 intronic variants in CFC1. The N21H variant was observed in 3 of 19 affected Caucasians, and the R47Q variant in another 2. Neither polymorphism was observed in Caucasian controls. Furthermore, all subjects with the N21H polymorphism had double outlet right ventricle. Transmission of both the N21H and R47Q polymorphisms from unaffected parents was demonstrated, and all three non-synonymous variants had significant allele frequencies in unaffected African-American subjects, suggesting that other factors must also contribute to laterality defects. CONCLUSIONS Three non-synonymous variants in CFC1 were identified, the N21H variant being associated with laterality defects in Caucasians, but not fully penetrant. One or more of these non-synonymous missense variants may act as a susceptibility allele in conjunction with other genes, and/or environmental factors, to cause laterality defects.