How to Read a 12-Lead EKG

An electrocardiogram, also known as an EKG or or ECG, is used in the diagnosis and assessment of cardiac activities. Medical and health professionals should have an in-depth knowledge in the interpretation of ECGs. A 12-lead ECG examines the electrical activity of the heart from12 points of view, which makes it efficient for diagnosing heart conditions. For you to be able to diagnose the ECG well, you must at least have basic knowledge on the parts and the functions of the heart.

Things You'll Need

• ECG Machine
• Alcohol wipes
• Chest leads

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Instructions

• 1

  Clean the area where electrode leads are to be placed. Use alcohol wipes. Arrange your leads on your patient’s chest accordingly. You may start with the limb leads. Begin with the right lead and attach it to the right wrist. The yellow is for the left wrist. The green lead is for the left leg and the black one for the right leg. For your chest leads, you can follow the directions below:
  V1 - 4th intercostals space at the right sternal border
  V2 - 4th intercostals space at the left sternal border
  V3 - between V2 & V4
  V4 - 5th intercostal space in the middle of the chest
  V5 - front axillary line at the same level as V4
  V6 - mid-axillary line at the same plane as V4 and V5

• 2

  Turn on the machine and erase previously recorded ECGs. Start a new ECG recording.

• 3

  ECG machines pick up electrical activity through the 4 limb and the 6 chest electrodes. There are several basic points that you have to keep in mind:

  V1 and V2 give data about the right heart.
  V3 and V4 give data on the intraventricular septum.
  V5 and V6 give data on the left side of the heart.
  The P wave represents the atrial systole (contraction).
  The QRS complex represents the ventricular systole.
  The T wave represents the ventricular diastole (relaxation).
  In one second, ECG tracing covers 5 large squares.

• 4

  Examine the ECG strip for any electrical activity through the wave forms. Determine the heart rate by counting the number of large squares between 2 QRS complexes. The normal rate is 60 to 100 beats per minute.

• 5

  Check for atrial activity through the P waves. Examine the ventricular activity of your heart as well. A normal activity should have equally spaces QRS complexes. Make sure to also check for prolonged QRS complexes.

• 6

  Diagnose your results. Here are common abnormal activities of the heart:

  Hyperkalemia. Tall T waves.
  Unstable angina. ST depression.
  Ischemic changes. T wave inversion.
  Acute myocardial infarction. ST wave elevation of 2 mm.
  Atrial flutter. P waves exhibits saw-tooth appearance.
  Atrial fibrillation. Chaotic rhythm from multiple sites.
  Ventricular fibrillation. Absence of P waves and irregular heart rate.
  Ventricular tachycardia. Heart rate of more than 100 bpm & wide QRS complexes.