Final answer:
A complete ECG waveform, representing one cardiac cycle, includes the P wave, QRS complex, and T wave. These components reflect the atrial and ventricular depolarization and repolarization that occur with each heartbeat.
Step-by-step explanation:
An electrocardiogram (ECG or EKG) is a test that records the electrical activity of the heart. The complete ECG waveform, which represents one cardiac cycle, includes several distinct components: the P wave, QRS complex, and T wave. These waves, segments, and intervals reflect the various stages of heart depolarization and repolarization during each heart beat. The depiction of this full cycle of a heart's electrical rhythm is often called a trace or tracing. The most commonly measured and graphed portion of an ECG is the lead II potential, which is the voltage difference between the right arm and the left leg, providing a comprehensive view of the heart's electrical function.
The P wave indicates atrial depolarization, which leads to atrial contraction. The QRS complex represents ventricular depolarization and precedes ventricular contraction, and the T wave shows ventricular repolarization, signaling the start of ventricular relaxation. Understanding and interpreting these ECG components is crucial for assessing heart health, diagnosing conditions, and monitoring for changes over time.
Modern ECG machines use multiple leads or electrodes placed on the chest to measure these electrical differences more accurately, offering detailed insights into the heart's function. Lead II potential is especially significant in showing the combined view of atrial and ventricular activities, and alterations in ECG can indicate issues such as cardiac ischemia or arrhythmias.