About ECG Smart Watch

ECG smart watches explained: How they work

Heart rate monitors are part and parcel of smart watches and fitness trackers now, but electrocardiogram (ECG/EKG) is the new sensor in town.

The technology is designed to help people keep closer tabs on their heart health, and can even be used to help identify atrial fibrillation (Afib) a serious medical condition that is a leading cause of stroke.

What is ECG?

Most of the wearable devices on the market at the moment have optical heart rate monitors inside them. This is a monitor that uses flashing LEDs to penetrate the skin and detect blood flow. When light is reflected off the flow of blood, it’s captured by the sensors. The algorithm then gets to work to turn that into an estimation of your heart rate.

But it’s not as accurate as it could be – especially where medical issues are involved.

Enter the electrocardiogram (ECG or EKG). Rather than measuring blood flow, it’s designed to measure how well your heart is working.

It’s a term you’d more commonly hear in the medical industry, referring to an electrocardiograph that's used to detect cardiac abnormalities.

Why would I buy an ECG smartwatch?

They key question for many people is 'why buy an ECG smartwatch?'. Well, for many (dare we say most people) the feature is something you'll likely use once and then forget about. But for a large subset of people, ECG is absolutely essential.

“ECG on wearable devices is super high value for a small segment. It is probably going to be more advantageous to our users over 50 than 20 - 25 years old, but we're trying to build something for everybody," Dr Conor Heneghan.

How to use the ECG feature.

We can perform ECG spot checks using the app on the watch. When you open the app, touch your fingers to the aluminium case and hold as instructed on the watch for an ECG to be taken.

How does ECG smartwatch tech work?

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 can ECG tech save your life?

An ECG carried out by a medical professional can identify many issues with your heart. But ECG devices designed to be used at home aren’t quite there yet.

Here is one of the way the ECG tech found in your smartwatch can currently save your life though, including the problems that they can identify and the others they might be able to.

Atrial fibrillation, a heart condition that can cause an irregular and abnormally fast heartbeat. It’s common and potentially deadly. It's also intermittent, which makes it difficult to detect.

The reason personal devices are effective at recognising this particular kind of arrhythmia (irregular heartbeat), and the reason Perlow cites for its effectiveness in his case, is because you can take them at any time.

“Individuals may be given a mobile ECG device by their health professional if they are concerned they may have paroxysmal Atrial fibrillation – that’s when it comes and goes. That way, if they are feeling signs and symptoms, they can take their own ECG when they are experiencing symptoms.”

How often should I take an ECG reading

Provided your heart gets a normal sinus rhythm, you’re likely to only need to periodically take an ECG test, just to check everything is in order.

But if you suffer from the feeling of your heart racing, palpitations or periods of feeling unwell, then you can use the ECG app as and when you need it. And it becomes an incredibly important health tool, right on your wrist.

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 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 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.