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Neonates with tetralogy of Fallot and symptomatic cyanosis (sTOF) may undergo palliation to delay complete repair (CR) with a systemic to pulmonary artery connection (SPC) or right ventricular outflow tract intervention (RVOTI). Comparison of these palliative strategies is lacking. Consecutive

“Hypoplastic left heart syndrome” is an unsatisfactory term describing lethal underdevelopment of the left ventricle (LV). It represents the more severe end of a spectrum of LV hypoplasia, mandating single-ventricle palliation or cardiac transplantation. Less severe “borderline” ventricular hypoplasia may instead allow various biventricular therapeutic strategies and better long-term outcomes. In this review, we consider factors causing and modifying the abnormal development of the LV. LV hypoplasia is typically seen in association with left ventricular outflow tract obstruction, itself part of a spectrum of related defects with common etiologies. Secondary responses to outflow obstruction are complex but involve abnormal flow dynamics and shear stresses that result in compromised and poorly orchestrated ventricular growth and development. Subsequent remodeling is likely influenced by genetic modifiers, including intrinsic myocardial growth signaling pathways, possibly including those of HAND transcription factors. In addition, during the latter stages of gestation, cardiomyocytes undergo a switch in myogenic potential and lose the ability to undergo mitosis. Ventricular hyperplasia can therefore no longer occur; remodeling is instead limited to muscular hypertrophy. Subtle differences in this switch in myogenic potential—and modulators thereof—are likely to be of clinical and therapeutic importance, especially in children with “borderline LVs” being considered for fetal interventions or post-natal biventricular repair strategies. Finally, by more clearly understanding the initiators and propagators of abnormal ventricular development, we can hope to lean away from grouping a heterogeneous group of infants together under the unsatisfactory term “hypoplastic left heart syndrome.”

ObjectivesThe purpose of this study was to evaluate the effects of dopamine on hemodynamic status and oxygen transport in neonates after the Norwood procedure.BackgroundDopamine is widely used to augment cardiac performance and increase oxygen delivery (Do2) in patients after cardiopulmonary bypass (CPB). This might be at the expense of increased myocardial and systemic oxygen consumption (Vo2), thus offsetting the improved Do2. This balance is particularly fragile in critically ill neonates.MethodsSystemic oxygen consumption was continuously measured with respiratory mass spectrometry in 13 sedated, paralyzed, and mechanically ventilated neonates for 72 h after the Norwood procedure. Arterial, superior vena caval, and pulmonary venous blood gases were measured to calculate pulmonary blood flow (Qp) and systemic blood flow (Qs), Do2, and oxygen extraction ratio (ERo2). Rate-pressure product was calculated. Dopamine at a dose of 5 μg/kg/min was routinely administered at cessation of CPB and terminated within the first 48 h. Hemodynamic and oxygen transport measures were obtained before and at 100 min after the termination of dopamine.ResultsTerminating dopamine was not associated with significant changes in arterial pressure, Qp, Qs, or Do2but was associated with a significant decrease in heart rate (p = 0.003), rate-pressure product (p = 0.03), and Vo2(−20 ± 11%, p < 0.0001), resulting in a significant decrease in ERo2(p = 0.01).ConclusionsDopamine induces a significant increase in Vo2in neonates after the Norwood procedure, and termination is associated with an improved balance of Vo2–Do2. These data further emphasize the importance of understanding changes in Vo2as well as Do2in infants after cardiac surgery.

"Hypoplastic left heart syndrome" is an unsatisfactory term describing lethal underdevelopment of the left ventricle (LV). It represents the more severe end of a spectrum of LV hypoplasia, mandating single-ventricle palliation or cardiac transplantation. Less severe "borderline" ventricular hypoplasia may instead allow various biventricular therapeutic strategies and better long-term outcomes. In this review, we consider factors causing and modifying the abnormal development of the LV. LV hypoplasia is typically seen in association with left ventricular outflow tract obstruction, itself part of a spectrum of related defects with common etiologies. Secondary responses to outflow obstruction are complex but involve abnormal flow dynamics and shear stresses that result in compromised and poorly orchestrated ventricular growth and development. Subsequent remodeling is likely influenced by genetic modifiers, including intrinsic myocardial growth signaling pathways, possibly including those of HAND transcription factors. In addition, during the latter stages of gestation, cardiomyocytes undergo a switch in myogenic potential and lose the ability to undergo mitosis. Ventricular hyperplasia can therefore no longer occur; remodeling is instead limited to muscular hypertrophy. Subtle differences in this switch in myogenic potential--and modulators thereof--are likely to be of clinical and therapeutic importance, especially in children with "borderline LVs" being considered for fetal interventions or post-natal biventricular repair strategies. Finally, by more clearly understanding the initiators and propagators of abnormal ventricular development, we can hope to lean away from grouping a heterogeneous group of infants together under the unsatisfactory term "hypoplastic left heart syndrome."

In the recent era, no congenital heart defect has undergone a more dramatic change in diagnostic approach, management, and outcomes than hypoplastic left heart syndrome (HLHS). During this time, survival to the age of 5 years (including Fontan) has ranged from 50% to 69%, but current expectations are that 70% of newborns born today with HLHS may reach adulthood. Although the 3-stage treatment approach to HLHS is now well founded, there is significant variation among centers. In this white paper, we present the current state of the art in our understanding and treatment of HLHS during the stages of care: 1) pre-Stage I: fetal and neonatal assessment and management; 2) Stage I: perioperative care, interstage monitoring, and management strategies; 3) Stage II: surgeries; 4) Stage III: Fontan surgery; and 5) long-term follow-up. Issues surrounding the genetics of HLHS, developmental outcomes, and quality of life are addressed in addition to the many other considerations for caring for this group of complex patients.

Upon repair of total anomalous pulmonary venous drainage (TAPVD) in children, the left-sided structures face a sudden increase in preload that may alter mitral valve function. We sought to determine the natural history of mitral regurgitation (MR) following TAPVD repair. 97 patients who underwent