Cardiac Investigations

There are many cardiac investigations that your child will undergo during their time at Great Ormond Street Hospital. These help to identify abnormalities and can help the medical team best prepare for potential treatment options.


An echocardiogram (echo) is an ultrasound of the heart. A picture of the heart is produced from which an accurate assessment of the size and function of the heart can be made. The scan takes from 30 to 40 minutes. This test is not painful, but children sometimes find the jelly on the probe a bit uncomfortable. Children can watch their favourite videos during the scan. Your child will have an echo at every Single Ventricle Service clinic appointment, and you will have the chance to ask the consultant questions following the scan.

In some circumstances, your child may have to go to the echo department, located on Walrus Ward.

Learn more about what happens when our child is having an echocardiogram.

Sometimes this happens under sedation, this will be discussed with you by your Single Ventricle Team. Learn more about what happens when your child needs an echocardiogram under sedation.

Electrocardiogram (ECG)

An ECG records the electrical signal as it is conducted throughout the heart. It is a simple test performed by placing sticky electrodes on the child’s chest, legs and wrists. An ECG is entirely safe, takes a few minutes and causes no pain, although the child may be anxious about the stickers and connecting wires.

Learn more about what happens when your child is having an electrocardiogram.

24-hour ECG (Holter)

A 24-hour ECG recording (or Holter) uses a small box similar in size to a portable stereo, from which three leads are attached by sticky pads to your child’s chest. This is an ECG monitor that continuously records the heartbeat over 24 to 48 hours. Children wear the monitor under their clothes and can continue with their normal daily life including sport and exercise. You and your child will be asked to document your child’s activities during the 24 to 48 hour period to match with the recording when the box is analysed. When the test is finished, you will be required to return the monitor to GOSH so that the results can be analysed.

Learn more about 24-hour ECG monitoring.

CT Scan

A CT scan (Computed Tomography) uses x-rays and computers to take pictures of the internal structures of your child’s body.

The CT scanner is a large doughnut-shaped machine with a hole in the centre through which a special bed can move. The scan can last anywhere from five minutes to 20 minutes, depending on the area and complexity of the scan. Although the bed will move through the scanner, it will not come into contact with your child.

Some children need to have injection of ‘contrast’ a liquid that shows up as a different colour on the scan. If your child is likely to need contrast, we will put local anaesthetic cream on their skin to make it numb before the injection.

If your child is apprehensive or scared of needles or injections or the scan itself, please telephone the Radiology play specialist before the appointment.

Learn more about what happens when your child is having a CT scan.