Pediatric Cardiology

A 10-year-old boy demonstrated both dual atrioventricular (A-V) nodal pathways and an A-V gap phenomenon. A fast and a slow A-V nodal pathway was identified, the faster pathway operating at the longer coupling intervals. As the coupling intervals were shortened, a critical range was reached during which distal conduction ceased but proximal conduction did not. Further shortening of the coupling interval was followed by resumption of distal conduction in association with appearance of the slower A-V nodal pathway. The gap in distal conduction occurred because the effective refractory period of the specialized ventricular conducting system was longer than the functional refractory period of the faster A-V nodal pathway. At shorter coupling intervals there was sufficient delay in the slower A-V nodal pathway to allow recovery of the distal conducting system and consequent resumption of conduction. To our knowledge, this is the first report of a child with this mechanism for the gap phenomenon.

A bidirectional Glenn shunt (BGS) was successfully incorporated into a two-ventricle repair for 10 patients (age, 3–17 years) who had congenital heart disease associated with severe pulmonary outflow obstruction. The BGS was used to volume-unload the pulmonary ventricle faced with residual outflow obstruction, thereby avoiding the need for insertion of a ventricle-to-pulmonary artery conduit. Transthoracic Doppler flow velocity analysis was used to determine transpulmonary peak systolic pressure drops as a measure of obstruction. Preoperative values ranged from 70 to 100 mmHg, and postoperative values ranged from less than 10 to 16 mmHg. At this writing, all patients are doing well 15 to 52 months after surgery. To gain further insight into the reduced pressure drop that may be achieved by decreasing flow rate across obstruction, a computer-based description of fluid flow was used to simulate blood traversing circumferentially narrowed passages. Overall pressure drops and associated flow energy losses were determined from numeric solutions (using finite-element analysis) to the Navier-Stokes equations for the proposed fluid reactions. Pressure drops and flow energy losses were found to decrease dramatically as flow rate was progressively reduced. For selected patients, a BGS can be an effective adjunct to the surgical treatment of pulmonary outflow obstruction. This approach avoids the use of a ventricle-to-pulmonary artery conduit, and thus the inevitable need in most patients for reoperations because of somatic growth, conduit failure, or both.

Laboratory monitoring of amiodarone therapy is recommended due to the high incidence of adverse events associated with the drug. The use of appropriate monitoring is unknown at pediatric hospitals. The Pediatric Health Information System database was queried during a 5-year period for all patients who received amiodarone while hospitalized. Use of thyroid function testing, hepatic function testing, electrocardiogram, pulmonary function testing, and chest X-ray for patients was identified. Incidence of individual monitoring tests and complete monitoring profile was identified and compared across patient demographic and clinical factors and pediatric hospital. A total of 1,703 patients met the study criteria, and the incidence of complete amiodarone monitoring for all patients was 7.6 %. The least common monitoring test performed was triiodothyronine at 19.4 %, and the most common was electrocardiogram at 89.7 %. Critically ill patients and neonates were more likely to have amiodarone monitoring. Considerable variation in monitoring practices between pediatric hospitals was identified. Monitoring of amiodarone therapy in patients admitted to pediatric hospitals is low. Future efforts to standardize care are warranted.

Although many changes have been discovered during heart maturation, the genetic mechanisms involved in the changes between immature and mature myocardium have only been partially elucidated. Here, gene expression profile changed between the human fetal and adult heart was characterized. A human microarray was applied to define the gene expression signatures of the fetal (13–17 weeks of gestation, n = 4) and adult hearts (30–40 years old, n = 4). Gene ontology analyses, pathway analyses, gene set enrichment analyses, and signal transduction network were performed to predict the function of the differentially expressed genes. Ten mRNAs were confirmed by quantificational real-time polymerase chain reaction. 5547 mRNAs were found to be significantly differentially expressed. “Cell cycle” was the most enriched pathway in the down-regulated genes. EFGR, IGF1R, and ITGB1 play a central role in the regulation of heart development. EGFR, IGF1R, and FGFR2 were the core genes regulating cardiac cell proliferation. The quantificational real-time polymerase chain reaction results were concordant with the microarray data. Our data identified the transcriptional regulation of heart development in the second trimester and the potential regulators that play a prominent role in the regulation of heart development and cardiac cells proliferation.

Myxoma, the most common primary cardiac tumor in adults, is rare in neonates. We describe a myxoma arising from the infundibulum of the right ventricle causing significant outflow tract obstruction in an otherwise normal newborn. Serial echocardiograms revealed an increasing gradient across the right ventricular outflow tract prompting surgery. The patient underwent successful excision of the myxoma with an uneventful recovery.

This pilot study aimed to assess the impact of using patient-specific three-dimensional (3D) models of congenital heart disease (CHD) during consultations with adolescent patients. Adolescent CHD patients (n = 20, age 15–18 years, 15 male) were asked to complete two questionnaires during a cardiology transition clinic at a specialist centre. The first questionnaire was completed just before routine consultation with the cardiologist, the second just after the consultation. During the consultation, each patient was presented with a 3D full heart model realised from their medical imaging data. The model was used by the cardiologist to point to main features of the CHD. Outcome measures included rating of health status, confidence in explaining their condition to others, name and features of their CHD (as a surrogate for CHD knowledge), impact of CHD on their lifestyle, satisfaction with previous/current visits, positive/negative features of the 3D model, and open-ended feedback. Significant improvements were registered in confidence in explaining their condition to others (p = 0.008), knowledge of CHD (p < 0.001) and patients’ satisfaction (p = 0.005). Descriptions of CHD and impact on lifestyle were more eloquent after seeing a 3D model. The majority of participants reported that models helped their understanding and improved their visit, with a non-negligible 30% of participants indicating that the model made them feel more anxious about their condition. Content analysis of open-ended feedback revealed an overall positive attitude of the participants toward 3D models. Clinical translation of 3D models of CHD for communication purposes warrants further exploration in larger studies.

There is evidence to suggest that patients undergoing a Norwood for non-HLHS anatomy may have lower mortality than classic HLHS, but differences in neurodevelopmental outcome have not been assessed. Our objective was to compare survival and neurodevelopmental outcome during the same surgical era in a large, well-described cohort. All subjects who underwent a Norwood–Sano operation between 2005 and 2014 were included. Follow-up clinical, neurological, and developmental data were obtained from the Western Canadian Complex Pediatric Therapies Follow-up Program database. Developmental outcomes were assessed at 2 years of age using the Bayley Scales of Infant and Toddler Development (Bayley-III). Survival was assessed using Kaplan–Meier analysis. Baseline characteristics, survival, and neurodevelopmental outcomes were compared between those with HLHS and those with non-HLHS anatomy (non-HLHS). The study comprised 126 infants (75 male), 87 of whom had HLHS. Five-year survival was the same for subjects with HLHS and those with non-HLHS (HLHS 71.8%, non-HLHS 76.9%; p = 0.592). Ninety-three patients underwent neurodevelopmental assessment including Bayley-III scores. The overall mean cognitive composite score was 91.5 (SD 14.6), language score was 86.6 (SD 16.7) and overall mean motor composite score was 85.8 (SD 14.5); being lower than the American normative population mean score of 100 (SD 15) for each (p-value for each comparison, <0.0001). None of the cognitive, language, or motor scores differed between those with HLHS and non-HLHS (all p > 0.05). In the generalized linear models, dominant right ventricle anatomy (present in 117 (93%) of patients) was predictive of lower language and motor scores. Comparative analysis of the HLHS and non-HLHS groups undergoing single ventricle palliation including a Norwood–Sano, during the same era, showed comparable 2-year survival and neurodevelopmental outcomes.