ECG Definition
An ECG displays the heart's electrical activity. It reveals the heart's rate and rhythm as well as the details regarding the condition of the heart. They are used to diagnose heart arrhythmias, heart attacks, pacemakers performance and heart failure.
With each heartbeat, an electrical signal moves from the atria to the ventricules. As it travels, the signal causes the heart to contract and pump blood. The process repeats with each heartbeat. An ECG machine records these electrical signals across multiple heart beats and produces an ECG strip that is interpreted by a healthcare professional.
ECG Reading
A normal ECG tracings includes waveform components which indicate electrical events during one heart beat. These waveforms are labeled P, Q, R, S, T and U.
P wave is the first short upward movement of the tracing. It indicates that the atria are contracting, pumping blood into the ventricles.
The QRS complex, normally begins with a downward deflection, Q; a larger upwards deflection, a peak (R); and then a downwards S wave. The QRS complex represents ventricular depolarization and contraction.
The PR interval indicates the transit time for the electrical signal to travel from the sinus node to the ventricles.
T wave is normally a modest upwards waveform representing ventricular repolarization.
ECG Interpretation Tutor
Use our online Workbook to practice your analysis skills and to learn over 40 different types of tracings. After your analysis is completed, our ECG tutor presents an analysis from an electrocardiogram expert.
ECG Interpretation Tutor
Arrhythmia Drills
Using multiple choice questions and answers, users are asked to identify arrhythmia tracings. Digital calipers are available to assist in analyzing each practice strip. Feedback is provided after each response.
Arrhythmia Practice Drills