Causes:
Usually accompanied by tall R wave in V1
Right ventricular hypertrophy
Pulmonary hypertension & chronic lung disease
COPD
Pulmonary embolism
Left posterior fascicular block
Lateral MI (from Q-waves in lead I)
Ventricular ectopy (VT)
TCA toxicity, sodium channel blocker toxicity
Hyperkalemia
Lead misplacement
Dextrocardia
Normal thin adults with horizontally positioned hearts
Usually accompanied by tall R wave in V1
Right ventricular hypertrophy
Pulmonary hypertension & chronic lung disease
COPD
Pulmonary embolism
Left posterior fascicular block
Lateral MI (from Q-waves in lead I)
Ventricular ectopy (VT)
TCA toxicity, sodium channel blocker toxicity
Hyperkalemia
Lead misplacement
Dextrocardia
Normal thin adults with horizontally positioned hearts
Right ventricular hypertrophy
Pulmonary hypertension & chronic lung disease
ECG axis
ECG rhythms
Vital signs 
ECG Stampede
Ventilation modes
Apneic oxygenation
Apgar score
T wave changes