Normal in pediatrics
Myocardial infarct (NSTEMI)
Myocardial ischemia (Wellen's) - T waves go up, then down
Hypokalemia - T waves go down, then up (or camel humped, one upright TW and upright U-wave in severe hypokalemia)
Hyperkalemia
Pulmonary embolism (RV strain)
Pulmonary hypertension, acute or chronic
Pulmonary disease - hyperventilation, pneumothorax, pneumonia
LVH with strain pattern
RVH
Bundle branch block (both left and right)
WPW
Pericarditis (stage 3)
CNS T waves (diffuse, deep)
Arrhythmogenic right ventricular dysplasia (may also have epsilon wave)
HOCM
Paced rhythm
Elevated intracranial pressure
MI (hyperacute T waves)
Hyperkalemia
Benign Early Repolarization
De Winter's T waves (acute LAD occlusion)
T wave changes
Normal in pediatrics
ST segment depression
Myocardial infarct 
De Winter's T waves
Myocardial ischemia 
AVR ST elevation
Hypokalemia - T waves go down, then up 