• EKG Electrodes"Heart Monitor" is Copyrighted by Flickr user: Rennett Stowe (Thomas) under the Creative Commons Attribution license.
  
  

Normal Sinus Rhythm

• A normal EKG reading is referred to as normal sinus rhythm. It is made up of waves displayed as a tracing on a metric grid. Each heartbeat consists of a P wave, a QRS complex, an ST segment, a T wave and U waves.
  
  

P Wave

• In normal sinus rhythm, each P wave appears as a bump in the tracing between 60 and 100 beats per minute. Normal P waves should appear less than 2.5 mm high and 0.11 seconds wide in lead II in a twelve-lead EKG.
  
  

PQ Interval

• After the P wave, there is a short straight line leading to the QRS complex.
  
  

QRS Complex

• A normal QRS complex follows the P wave and appears as a spike on the tracing. It should be less than 0.12 seconds long.
  
  

ST Segment

• The ST segment is a straight line between the QRS complex and the T wave and should not display any elevation or depression.
  
  

T Wave

• Following the QRS complex, a T wave appears as a slightly smaller bump than the P wave. It should not be tall, flattened or inverted.