They are usually observed in people suffering from hypothermia with a temperature of less than 32 °C (90 °F), though they may also occur in people with high blood levels of calcium (hypercalcemia), brain injury, vasospastic angina, acute pericarditis, or ventricular fibrillation and could also be a normal variant.
J wave
U wave
QRS complex
P wave 
Delta wave
T wave
ST segment
Apex beat