Definition
An ECG displays cardiac electrical activity. It reveals heart rate, rhythm and cardiac abnormalities. ECG can be used to evaluate heart arrhythmias, pacemakers performance and heart failure.
During each heartbeat, an electrical impulse is transmitted from the atria to the ventricles. This electrical energy causes the heart to contract and thereby pump blood. An ECG machine captures 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
Our online workbook cab be used to practice interpretation 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 try to identify arrhythmia tracings. Digital calipers are available to assist in analyzing each practice strip. Feedback is provided after each response.
Arrhythmia Practice Drills