Seizure
Breath-holding spell
Hyperventilation syndrome
Pregnancy (especially ectopic)
Hypoglycemia
Cardiac disease
Tet spell
Hypertrophic cardiomyopathy
Brugada Syndrome
Dysrhythmias
Long QT syndrome
Anomalous coronary arteries
Toxicologic exposure (stimulants or depressant)
CO poisoning
Ethanol toxicity
Drugs of abuse
Tet spell
Hypertrophic cardiomyopathy
Brugada Syndrome
Dysrhythmias
Long QT syndrome
Anomalous coronary arteries
CO poisoning
Ethanol toxicity
Drugs of abuse
Cyanotic<unk> 
Total anomalous pulmonary venous return
Transposition of the great arteries
Tricuspid atresia
Truncus arteriosus
Ebstein anomaly
Hypoplastic left heart syndrome
Acyanotic
AV canal defect
Atrial septal defect (ASD)
Ventricular septal defect (VSD)
Cor triatriatum
Patent ductus arteriosus (PDA)
Pulmonary/aortic stenosis
Coarctation of the aorta
Differentiation by pulmonary vascularity on CXR
Increased pulmonary vascularity
Large ASD
Large VSD
Total anomalous pulmonary venous return
Transposition of the great arteries
Truncus arteriosus
Decreased pulmonary vascularity<unk> 
Rare heart diseases with pulmonic stenosis<unk> 
Total anomalous pulmonary venous return
Transposition of the great arteries
Tricuspid atresia
Truncus arteriosus
Ebstein anomaly
Hypoplastic left heart syndrome
AV canal defect
Atrial septal defect (ASD)
Ventricular septal defect (VSD)
Cor triatriatum
Patent ductus arteriosus (PDA)
Pulmonary/aortic stenosis
Coarctation of the aorta
Increased pulmonary vascularity
Large ASD
Large VSD
Total anomalous pulmonary venous return
Transposition of the great arteries
Truncus arteriosus
Decreased pulmonary vascularity<unk> 
Rare heart diseases with pulmonic stenosis
Large ASD
Large VSD
Total anomalous pulmonary venous return
Transposition of the great arteries
Truncus arteriosus<unk> 
Rare heart diseases with pulmonic stenosis
Tetralogy of Fallot
Seizure
Transposition of the great arteries
Breath-holding spell
Ebstein anomaly
Hyperventilation syndrome
Tricuspid atresia
Pregnancy 