An ECG maps electrical signals in the heart. The ECG shows the heart's rate, rhythm and other information regarding the heart electrical signal and its condition. ECGs are used to diagnose heart attacks, heart arrhythmias, pacemakers performance and heart failure.
With each heartbeat, an electrical signal moves from the top of the heart to the bottom. As it travels, the signal causes the heart to contract and pump blood. The process repeats with each new 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 Strips - Electrocardiograms
An ECG waveform can include several components which indicate electrical activity during a heart beat. These components are labeled P, Q, R, S, T and U.
The P wave is the first short upward movement of the ECG tracing. It indicates atrial contraction with blood moving into the ventricles from the atria.
The QRS complex, normally starts with a downward deflection, Q; a larger upwards deflection, a peak (R); and then a downwards S wave. The QRS complex marks ventricular depolarization and contraction.
The PR interval indicates the transit time for the electrical signal to travel from the sinus node to the ventricles.
The T wave is normally a smaller upwards waveform, representing ventricular re-polarization.
Basic ECG Interpretation
Our ECG Tutorial and Reference Guides provide basic lessons for ECG analysis as well as a quick reference guide for over 35 categories of cardiac conditions. The arrhythmia drills and quizzes allow you to practice ECG analysis.
ECG Interpretation Tutor
Use our online ECG 'Workbook' to practice your ECG analysis skills and to learn over 40 different types of ECG tracings. After your analysis is completed, our ECG tutor presents an analysis from an ECG expert.
ECG Interpretation Tutor
ECG Arrhythmia Drills
Using multiple choice questions and answers, users are asked to identify arrhythmia tracings. Digital calipers are available to assist in analyzing each ECG practice strip. Feedback is provided after each response.
Arrhythmia Practice Drills
Our ECG tutorial guide provides information about many types of arrhythmias. For each ECG arrhythmia we provide multiple electrocardiogram tracings. ECG analysis is provided with a concise summary of the ECG's key features. Tracing features can be measured using our digital calipers.
ECG Tutorial - Introduction
The focus of this introductory ECG tutorial is to provide a tutorial about the main features of ECGs along with a method for analyzing ECGs. This method includes assessment of rhythm, calculating heart rate, observing P-wave forms, measurement of EKG intervals and segments and the evaluation of other relevant waves.
ECG practice exercises serve to reinforce the lesson content.