The electrocardiogram (ECG) is a diagnostic tool that measures and records the electrical activity of the heart in exquisite detail. Interpretation of these details allows diagnosis of a wide range of heart conditions. These conditions can vary from minor to life threatening.

The term electrocardiogram was introduced by Willem Einthoven in 1893 at a meeting of the Dutch Medical Society. In 1924, Einthoven received the Nobel Prize for his life's work in developing the ECG.

The ECG has evolved over the years.

• The standard 12-lead ECG that is used throughout the world was introduced in 1942.
• It is called a 12-lead ECG because it examines the electrical activity of the heart from 12 points of view.
• This is necessary because no single point (or even 2 or 3 points of view) provides a complete picture of what is going on.
• To fully understand how an ECG reveals useful information about the condition of your heart requires a basic understanding of the anatomy (that is, the structure) and physiology (that is, the function) of the heart.

The ECG records the electrical activity that results when the heart muscle cells in the atria and ventricles contract.

• Atrial contractions (both right and left) show up as the P wave.
• Ventricular contractions (both right and left) show as a series of 3 waves, Q-R-S, known as the QRS complex.
• The third and last common wave in an ECG is the T wave. This reflects the electrical activity produced when the ventricles are recharging for the next contraction (repolarizing).
• Interestingly, the letters P, Q, R, S, and T are not abbreviations for any actual words but were chosen many years ago for their position in the middle of the alphabet.
• The electrical activity results in P, QRS, and T waves that have a myriad of sizes and shapes. When viewed from multiple anatomic-electric perspectives (that is, leads), these waves can show a wide range of abnormalities of both the electrical conduction system and the muscle tissue of the heart's 4 pumping chambers.

 METROPOLITAN HOSPITAL COST