What you need to know about technology for serious health tracking.
What is an ECG
An electrocardiogram (also called an ECG or EKG) is a test that records the timing and strength of the electrical signals that make the heart beat. By looking at an ECG, a doctor can gain insights about your heart rhythm and look for irregularities.
An ECG records the tiny electrical signals that are generated by the beating of your heart under your skin, which it presents as a trace. This then allows trained professionals, machines or wearables to understand more about how your heart is functioning – and determine if there are any abnormalities.
“In the simplest sense, it can tell you the heart rate (how fast), the rhythm (how regular), the state of the conduction system and muscle tissue (heart attacks), and even the level of certain chemicals like potassium in the blood, and the effect of medication,” says Dr Keith Grimes, GP and Clinical Innovation Director at Babylon Health.
An electrocardiograph in a medical setting usually requires placing electrodes on the skin situated close to the heart, which measure electrical activity produced by the heart as it contracts. The electrical activity is sent to a receiver that records the information, and this is where the heart's rhythm can be analysed and irregularities can be detected.
How the ECG app works
The ECG app on JM ECG PPG Smart Watch or later generates an ECG that is similar to a single-lead (or Lead I) ECG. In a doctor’s office, a standard 12-lead ECG is usually taken. This 12-lead ECG records electrical signals from different angles in the heart to produce twelve different waveforms. The ECG app on JM ECG PPG Smart Watch measures a waveform similar to one of those twelve waveforms. A single-lead ECG is able to provide information about heart rate and heart rhythm and enables classification of AFib. However, a single-lead ECG cannot be used to identify some other conditions, like heart attacks. Single-lead ECGs are often prescribed by doctors for people to wear at home or within the hospital so that the doctor can get a better look at the underlying rate and rhythm of the heart. However, the ECG app on JM ECG PPG Smart Watch or later allows you to generate an ECG similar to a single-lead ECG without a prescription from your doctor.
How to get the best results with your ECG Watch
Rest your arms on a table or in your lap while you take a recording. Try to relax and not move too much.
Make sure that your JM ECG Smart Watch isn’t loose on your wrist. The band should be snug, and the back of your JM ECG Smart Watch needs to be touching your wrist.
Make sure that your wrist and your JM ECG Smart Watch are clean and dry.
Make sure that your JM ECG Smart Watch is on the wrist that you selected in the app. To check, open the app, then go to General > Watch Orientation.
Move away from any electronics that are plugged into an outlet to avoid electrical interference.
A small percentage of people may have certain physiological conditions preventing the creation of enough signal to produce a good recording — for example, the positioning of the heart in the chest can change the electrical signal levels, which could impact the ECG app’s ability to obtain a measurement.
Liquid-free contact is required for the ECG app to work properly. Use of the ECG app may be impacted if the JM ECG Smart Watch and/or skin aren't entirely dry. Make sure that your wrist and hands are thoroughly dry before attempting a reading. To ensure the best reading after swimming, showering, heavy perspiration, or washing your hands, clean and dry your JM ECG Smart Watch. It may take up to one hour for your JM ECG Smart Watch to completely dry.
The problems with false positives – and negatives
ECG devices available to consumers can detect a range of heart problems, whether they’ve been cleared to or not, but that doesn’t mean they should replace a trip to your doctor.
“Reading an ECG is tricky,” Dr Grimes explains. “Current technology uses machine learning to detect common abnormalities, but personal ECG, like the kind you find on the JM ECG PPG Smart Watch, is not as accurate as medical devices.”
Personal ECG devices are proven to save lives, but on the flip-side they can still miss major problems or cause people to worry they have issues with their heart when they don’t. Dr Grimes calls these “false negatives” and “false positives”.
Although many in the medical profession are warning people to be wary of the results they get from their JM ECG PPG Smart Watch, or other ECG device, having more control over our health at home is going to become more widespread over time.
That means instead of advising against ECG devices, people need to be informed that readings might not always be accurate – but it’s best to head to a medical professional if you see a reading you’re concerned about, to get it checked out.