Electrocardiogram What is an ECG and what can it show? An electrocardiogram (ECG) test records the electrical activity of your heart. It is a simple test that lets doctors look at certain aspects of how your heart is working. To work effectively, the muscles in your heart need to contract at different times. This is coordinated by small electrical signals in your heart. An ECG test records the timing of these electrical signals. An ECG test can tell if there are any problems with the heart’s rhythm. How is an ECG done? An ECG is done by sticking small metal contacts (electrodes) to your chest. These contacts are connected by wires to the ECG machine that records the results, usually on a piece of paper. The test usually only takes a few minutes and is often repeated at clinic visits in people who have pulmonary hypertension. In some cases, your healthcare team may ask that a 24-hour ECG is done. This means that your heart is monitored as you go about your normal daily routine. If you are having a 24-hour ECG, the machine that records the information is similar in size to a large iPod, so that it can be carried around with you. Watch a video of an ECG, taken from the Pulmonary Hypertension Association (PHA UK) DVD Understanding Pulmonary Hypertension – a guide to diagnosis and treatment, here.