The electrocardiogram is a recording of the electrical activity of your
heart. The fundamentals of the EKG recording was described by Willem Einthoven, who developed a machine in 1903
called an electrokardiogramma (EKG). He was awarded the Nobel prize in 1924.
The EKG is a simple way to diagnose many heart conditions, such as
heart block, arrhythmias, heart enlargement, cardiomyopathy, heart attacks, and syndromes such as long QT, Brugada, and RV
dysplasia.
A normal heart beat originates from a small electrical pulse from the
pacemaker, or sinus node, of the heart. The heart cells contract and spread the electical current from
one cell to another in a specific sequence, to optimize the efficiency of the heart. Cells change their electric charge by means of depolarization and repolarization. This process occurs when charged
ion inside the cell travel out through the membrane and positive ions travel inward. The electical waves are recorded
in millivolts by the EKG, and are recorded on paper. These electical waves are recorded by electrodes, which are
placed in certain locations across the chest, and on each arm and leg. If there is mucle damage or block in electrical
conduction, these abnormalities will be detected on the EKG.
There are three distinct waves on the EKG. The first wave, the P wave, represents depolarization
of the top chambers, or atria. The next wave is the largest, the QRS complex of waves, represents depolarization of
the ventricles. The T wave is last, and represents repolarization of the ventricles. The repolarization wave of
the atrium is usually hidden by the QRS complex. These waves will have different characteristics in the 12 different
recorded leads (directions of recording).
