Patricio A. Frias

Infrequently studied congenital anomalies as clues to the diagnosis of maternal diabetes mellitus.

The aim of this study was to identify congenital anomalies (CA) among infants of women with diabetes mellitus (DM) that, even though infrequent or infrequently reported, may suggest diabetic teratogenesis. Using 1976–2005 data from the Spanish Collaborative Study of Congenital Malformations (ECEMC), we compared the frequency of selected CA among 130 infants with CA born to women with pregestational DM (PGDM) and 30,009 infants with CA whose mothers had normal glucose tolerance (NGT). To identify which CA were not only significantly more frequent among infants of mothers with PGDM, but also more specific, we calculated the quotient of their frequencies (frequency ratio: FR). The same analysis was made using data from 927 infants of mothers with gestational DM (GDM). Among the studied defects, several were statistically significantly more frequent among infants of PGDM mothers than among infants of mothers with NGT, although the specificity of their association with DM varied, as indicated by the values of the FR. These included: anorectal atresia/stenosis (FR = 2.81; P = 0.03), hallucal polydactyly (FR = 3.62; P = 0.002), heterotaxy (FR = 5.70; P = 0.049), hypertrophic cardiomyopathy (HCM) (FR = 61.60; P = 0.000000), multicystic dysplastic kidneys (MDK) (FR = 5.13; P = 0.0002), and thymus aplasia/hypoplasia (FR = 29.62; P = 0.000001). The only CA significantly more frequent among infants of women with GDM were HCM (FR = 8.60; P = 0.002) and MDK (FR = 1.80; P = 0.01). Our results suggest that maternal PGDM should be suspected in children with hallucal polydactyly, anorectal atresia/stenosis, heterotaxy, or aplasia/hypoplasia of the thymus. The presence of transient HCM or MDK in a newborn suggests maternal PGDM or GDM. These observations are important in view of the increasing worldwide frequency of DM and the high proportion of individuals with DM in whom the condition remains undiagnosed.

Outcome of isolated bicuspid aortic valve in childhood.

OBJECTIVE To evaluate the outcomes associated with isolated bicuspid aortic valve (BAV) during childhood and adolescence. STUDY DESIGN Analysis of a large single institutional cohort of children (n=981) with isolated BAV was undertaken to determine the prevalence of significant ascending aortic dilation and risk of cardiac events. Subjects with known genetic disorders, critical aortic stenosis (intervention required in infancy), or additional lesions such as coarctation of the aorta were excluded. Aortic dimensions were derived from echocardiography, and values were plotted as Z scores. Clinical outcomes included death, aortic dissection, balloon aortic valvuloplasty, or cardiac surgery. RESULTS The median age of the subjects at diagnosis was 8.3 years. At the time of the last pediatric follow-up, 7% of the subjects had moderate aortic regurgitation or greater, and the median Z score for the ascending aorta was +2.31. There were 9427 patient years of follow-up. Primary cardiac events occurred in 38 subjects, yielding an event rate of 0.004 per patient year. Eleven subjects (1.1%) underwent aortic valve surgery. Thirty subjects (3.0%) underwent balloon dilatation of the aortic valve. There was a single case of endocarditis. There were no cardiac-related deaths and no cases of aortic dissection. CONCLUSIONS The incidence of primary cardiac events in children with BAV is relatively low, approximately 3-fold lower than in young adults, and is generally related to aortic stenosis amenable to balloon dilatation. Although mild ascending aortic dilation is common in children, the clinical course is relatively benign. In this series, aortic dissection did not occur. Whether elective surgery for the dilated aorta has a role in children remains unknown.

Long-Term Risk of Fatal Malignancy Following Pediatric Radiofrequency Ablation

Children undergoing radiofrequency ablation (RFA) are believed to be at increased risk of developing malignancy caused by radiation, although the magnitude of this risk is incompletely understood. We previously reported a strategy to reduce radiation exposure during pediatric RFA. In a cohort of 15 subjects (median age 12 years, range 9 to 17), radiation was measured using dosimeters at 5 sites. The risk of malignancy using measured radiation absorbed dose was calculated. International Council for Radiation Protection 60 risk estimates were applied to calculate absorbed organ doses. Median duration of combined biplane fluoroscopy was 14.4 minutes. Of the 5 dosimeter locations, the right scapular location had the highest median radiation exposure (43 mGy). Incorporating data from the 5 dosimeters, the risk model calculated that the organ with the greatest absorbed dose and at greatest risk of malignancy was the lung, followed by bone marrow, then breast. Thyroid and ovary exposures were negligible. The increased lifetime risk of fatal malignancy was 0.02% per single RFA procedure. In conclusion, with appropriate measures to reduce radiation exposure, the increased risk of malignancy after a single RFA procedure in children is low. These data should be of help counseling families and will contribute to analysis of the relative risk reduction benefits of such novel imaging approaches as a magnetic resonance imaging-based catheterization laboratory.

Quantifying and Minimizing Radiation Exposure During Pediatric Cardiac Catheterization

This study reports findings from evaluations of new technologies to measure radiation exposure during pediatric cardiac catheterization procedures. A strategy of pulsed fluoroscopy and low power settings resulted in significantly lower patient radiation exposure compared to conventional 60 frames/sec, high-power settings during fluoroscopy. During radiofrequency ablation procedures, thyroid and thoracic skin sites outside the direct fluoroscopic field received minimal radiation exposure. Intrathoracic radiation exposure was measured with the use of an esophageal dosimeter. In conclusion, strategies to reduce total radiation exposure should be employed, radiation dose should be measured, and assessment of radiation skin injury should be included in postcatheterization assessment.

Early and delayed atrioventricular conduction block after routine surgery for congenital heart disease

OBJECTIVES Patients undergoing surgical closure of ventricular septal defects are at risk for immediate or delayed atrioventricular conduction block. Our goal was to better define the incidence of delayed atrioventricular conduction block. METHODS A retrospective review was conducted of hospital records and pacemaker database for ventricular septal defect, atrioventricular canal, and tetralogy of Fallot repairs between 1999 and 2004. A total of 922 patients were identified (atrioventricular canal in 197, tetralogy of Fallot in 222, and ventricular septal defect in 503). Median follow-up was 4.1 years. RESULTS There were 472 male and 450 female patients, median age 6 months (0-444 months) and median weight 5.8 kg (1.3-116 kg) at surgery. Postoperative atrioventricular conduction block developed in 21 (2.3%) of the 922, being transient, with return of conduction 3 days (1-14 days) after surgery, in 13 (1.4%) and permanent, with pacemakers implanted 10 days (6-20 days) after surgery, in 8 (0.9%). Of the 905 patients at risk for delayed atrioventricular conduction block, 3 (0.3%) had second- or third-degree block at 2, 8, and 16 months after surgery. Two of these 3 had transient postoperative block. For isolated ventricular septal defects, the incidence was 1 (0.2%) of 496. There were 8 late deaths at 31 months (7-45 months) after surgery. Five had normal conduction at death, but for 3 patients the conduction status at death could not be determined. Including these 3 patients as possible cases of delayed atrioventricular block yields an incidence of 0.3% to 0.7%. CONCLUSIONS The incidence of early atrioventricular conduction block requiring a pacemaker was 0.9% and that of delayed atrioventricular conduction block was 0.3% to 0.7%. Transient atrioventricular conduction block may be a marker for increased risk of delayed block. These data may be useful for evaluation of new techniques.

Outcomes Following Electroanatomic Mapping and Ablation for the Treatment of Ectopic Atrial Tachycardia in the Pediatric Population

Ectopic atrial tachycardia (EAT) is often resistant to medical therapy, with radiofrequency ablation (RFA) being a preferred treatment option. Three-dimensional (3-D) electroanatomic mapping was introduced as a tool for improved substrate localization, although there are no published data with this technology in pediatric patients with EAT. The objective of this study was to examine our experience with 3-D mapping and standard mapping in this patient population. We used retrospective chart review of pediatric patients with EAT requiring RFA from 1993 to 2004. We analyzed the method of ablation, acute success and recurrence rates, procedure and fluoroscopy times, and cardiac function. Twenty-five patients underwent 31 RFA procedures. All patients had been followed for >6 months (6 months to 7 years). Standard mapping (Group 1) was used in 11 patients (5F/6M, 1.4–11.8 years) who underwent 13 RFA procedures; 3-D mapping (Group 2, October 2000–2004) was used in 16 patients (8 F/8M, 2.7–17 years) who underwent 18 RFA procedures. Left-sided focus was present in 6/13 in Group 1 and 7/18 in Group 2 (all transeptal, NS). There was a trend toward fewer lesions with 3-D mapping (15 ± 14, median 9.5 in Group 1; 8 ± 6, median 6.5 in Group 2, NS). Acute success was more likely for patients in which 3-D mapping was utilized (10/13 Group 1 vs. 18/18 Group 2, p < 0.04). Recurrence or persistence of tachycardia at follow-up (2 weeks to 1 year) was documented in 7/13 cases in Group 1, compared to only 2/18 cases in Group 2 (p = 0.01). Six patients underwent repeat RFA: two patients using standard mapping (one failure, one success) and four patients using 3-D mapping [all acute and long-term (>1 year) success]. Procedure times (232 ± 84 vs. 268 ± 72 min, skin-to-skin) and fluoroscopy times (47 ± 24 vs. 40 ± 20 min) were similar (NS). Of the 25 pts, 17 (7 in Group 1, 10 in Group 2, NS) presented with cardiomyopathy [Ejection fraction (EF), 38.6 ± 12.1%]. Successful RFA resulted in improved EF (61.1 ± 11.6%, p < 0.0001) in the 14 patients in whom pre-RFA and post-RFA echocardiograms were available. Compared to standard techniques, 3-D electroanatomic mapping has resulted in no acute failures, statistically reduced recurrence rates, and improved overall success in the management of EAT.

Does Ablation of Supraventricular Tachycardia in Children with a Structurally Normal Heart Improve Quality of Life

INTRODUCTION Ablation has become first-line therapy for managing many pediatric patients with atrioventicular accessory pathway or atrioventricular nodal-mediated supraventricular tachycardia (SVT). Studies to date have all focused on elimination of the SVT substrate; yet, there are no studies to document whether this results in improved quality of life (QoL) scores. OBJECTIVE The objective of this study was to evaluate whether a successful catheter ablation improved QoL scores in pediatric patients. PATIENT AND METHODS Pediatric patients between the age of 5 and 18 years with structurally normal hearts and re-entry SVT that were referred to the electrophysiology laboratory between October 2004 and June 2006 at the Childrens Healthcare of Atlanta were eligible to be enrolled in the study. The Pediatric Quality of Life Inventory cardiac model questionnaire was administered to patients prior to and 6 months following catheter ablation. Areas evaluated were physical, emotional, social, school, and psychosocial function. The paired t-test was used to test the difference between pre- and post-time points for the study groups. P value <.05 was considered significant. RESULTS Forty-three patients consented to initial enrollment and returned the initial questionnaires. Seven patients did not have ablations performed during the electrophysiology study and therefore were excluded from further analysis. Complete pre- and post-ablation data were available for 27 patients. Comparing pre-ablation data with post-ablation data, there was significant improvement in all measured areas following successful elimination of tachycardia substrate. Patients reported lowest social and physical functioning scores pre-ablation. The greatest reported improvement post-ablation was in physical functioning. CONCLUSION Successful elimination of SVT substrate results in improved pediatric QoL scores as reported by patients.

Natural History and Current Therapy for Complete Heart Block in Children and Patients with Congenital Heart Disease

Complete heart block, either congenital or acquired, in children and patients with congenital heart disease is a relatively frequent occurrence requiring therapy. The natural history of this condition has been distorted by the advent of new diagnostic and therapeutic modalities. The therapy of complete heart block is evolving with new data suggesting that traditional treatment strategies utilizing right ventricular apical pacing may have inadvertent deleterious effects on cardiac function. In the following manuscript, the natural history of complete heart block is reviewed and the current therapy examined.

Epicardial Ablation of Ventricular Tachycardia in a Child on Venoarterial Extracorporeal Membrane Oxygenation

Epicardial catheter ablation has been demonstrated to be safe and effective in adults, but there are limited reports in the pediatric population. We report the epicardial ablation of an incessant, hemodynamically compromising ventricular tachycardia in a 13-month-old patient on venoarterial extracorporeal membrane oxygenation. The procedure resulted in elimination of tachycardia substrate with improved cardiac size and function at follow-up. Despite a reasonable long-term outcome in this child, epicardial ablation in young patients should be reserved for similarly dire circumstances.

Supervised embedding of textual predictors with applications in clinical diagnostics for pediatric cardiology

OBJECTIVE Electronic health records possess critical predictive information for machine-learning-based diagnostic aids. However, many traditional machine learning methods fail to simultaneously integrate textual data into the prediction process because of its high dimensionality. In this paper, we present a supervised method using Laplacian Eigenmaps to enable existing machine learning methods to estimate both low-dimensional representations of textual data and accurate predictors based on these low-dimensional representations at the same time. MATERIALS AND METHODS We present a supervised Laplacian Eigenmap method to enhance predictive models by embedding textual predictors into a low-dimensional latent space, which preserves the local similarities among textual data in high-dimensional space. The proposed implementation performs alternating optimization using gradient descent. For the evaluation, we applied our method to over 2000 patient records from a large single-center pediatric cardiology practice to predict if patients were diagnosed with cardiac disease. In our experiments, we consider relatively short textual descriptions because of data availability. We compared our method with latent semantic indexing, latent Dirichlet allocation, and local Fisher discriminant analysis. The results were assessed using four metrics: the area under the receiver operating characteristic curve (AUC), Matthews correlation coefficient (MCC), specificity, and sensitivity. RESULTS AND DISCUSSION The results indicate that supervised Laplacian Eigenmaps was the highest performing method in our study, achieving 0.782 and 0.374 for AUC and MCC, respectively. Supervised Laplacian Eigenmaps showed an increase of 8.16% in AUC and 20.6% in MCC over the baseline that excluded textual data and a 2.69% and 5.35% increase in AUC and MCC, respectively, over unsupervised Laplacian Eigenmaps. CONCLUSIONS As a solution, we present a supervised Laplacian Eigenmap method to embed textual predictors into a low-dimensional Euclidean space. This method allows many existing machine learning predictors to effectively and efficiently capture the potential of textual predictors, especially those based on short texts.