The electrocardiogram, or ECG, is one of the most basic diagnostic studies performed in emergency and critical care units. Unfortunately, many students and healthcare professionals find ECG interpretation a difficult skill to learn, mainly because they cannot relate theory to practice. To help address the issue, this module will reinforce ECG learning using the most effective technique available, which is to learn by doing. You will be asked to answer a simple ECG quiz below, which will test your knowledge of essential concepts in electrocardiography.
But first, let us have a short review.
What is an ECG?
The heart's network of contractile cells allows for a coordinated pumping mechanism to ensure that adequate blood is transported to the different tissues of the body. Normally, control of cardiac contraction (or heartbeat) is coordinated by the heart’s natural pacemaker, the sino-atrial (SA) node. The action potential generated in the SA-node spreads to the contractile cells of the heart via specialized conductive fibers.
Highly specific patterns of cardiac electrical activation can be obtained using various methods. Among these methods, the electrocardiography is the most common clinical tool used to observe and record cardiac electrical activity. In an ECG the changes in the potential difference or voltage in the different regions of the heart are plotted against time.
There are several conditions that cause ECG abnormalities, particularly myocardial ischemia, conduction defects, intake of certain drugs (e.g. digoxin), and electrolyte imbalance. In-depth analysis and clinical correlation is usually required to determine the exact etiology.
Now it is time to take the ECG quiz.