An electrocardiogram (ECG or EKG) is a graphical representation of the electrical activity of the heart over time. A typical ECG recording consists of several key components that correlate with the different phases of a cardiac cycle.
In a normal ECG, the major parts include:
- P Wave: Represents atrial depolarization, reflecting the electrical activity that leads to the contraction of the atria.
- QRS Complex: Indicates ventricular depolarization. It typically is a sharp, larger spike indicating that the ventricles are contracting to pump blood out of the heart.
- T Wave: Corresponds to ventricular repolarization, a phase where the ventricles recover from contraction and prepare for the next heartbeat.
In a complete cardiac cycle, the P wave occurs first, followed by the QRS complex, and finally the T wave. Between these waves, there are segments and intervals that represent different phases of the heart’s electrical activity:
- PR Interval: The period from the start of the P wave to the start of the QRS complex, indicative of the time the electrical impulse travels from the atria to the ventricles.
- ST Segment: Follows the QRS complex and represents the period when the ventricles are depolarized.
- QT Interval: Extends from the start of the QRS complex to the end of the T wave, encompassing the time it takes for the ventricles to depolarize and repolarize.
Labeling these parts on an ECG tracing helps healthcare professionals understand the heart function and diagnose various cardiac conditions. Always consult a healthcare professional for a proper interpretation of an ECG.