Apple Keynote (screenshot)

Here’s everything you need to know about the Apple Watch ECG sensor

Apple has made its Series 4 Watch official yesterday. The timepiece comes with lots to look forward to including a bigger display, a slate of new health and fitness features, performance upgrades and more. Arguably the most interesting of the lot is the FDA-approved ECG sensor.

First for the science lesson.

With each beat your heart sends out an electrical impulse. In addition to the optical heart rate sensor, Series 4 comes with an ultrathin chromium silicon carbon nitride layer applied to the sapphire crystal on the back of the device. This reads electrical heart impulses from your wrist. The second, equally important, piece of the puzzle is the digital crown titanium electrode. It reads electrical heart impulses from your fingertip.

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Image source: Apple

ECG readings are on-demand. To take a measurement simply rest your finger against the digital crown while wearing the watch. This creates a closed circuit between the digital crown and the sensor on the back. Built in electrodes will then work to detect electrical impulses from the heart.

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Image source: Apple

It takes just 30 seconds for a pulse waveform to be generated. You’ll get a full report in the yet-to-be released ECG app that will let you know if your heart rhythm is normal or there are issues. Everything is stored in the app along with any notes you’ve entered on related symptoms. The app also generates a PDF so you can forward the info on to your doctor.

everything you need to know about apple s new ecg sensor - Here's everything you need to know about the Apple Watch ECG sensorNow you might be saying to yourself, why in the world would I need a home ECG! I was just fine without it.

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Apple says the ECG sensor is capable of generating a pulse waveform similar to that generated by a professional single-lead electrocardiogram. This type of information will let you know whether your heart rhythm shows signs of atrial fibrillation (which indicates there is a problem), or sinus rhythm (which means your heart is beating in a normal pattern).

In atrial fibrillation, electrical conduction in the heart becomes disorganised. Anyone can have an irregular heartbeat and the causes are numerous, but it’s more common in people over 60.

Signs include dizziness, weakness and fatigue. The disease is treatable, but many people don’t feel symptoms. The trick is detecting it in time. With the right treatment and some lifestyle changes, those suffering from irregular heartbeat can stay active and energetic.

Apple says its ECG monitor will not do a perfect job, but the hope is it will be of particular use to people who are not aware they have the condition. Collating this type of data will create interesting opportunities to identify associations with other diseases, too.

CDC estimates there are between 2.7 and 6.1 million Americans living with the condition. The device would be particularly useful to this segment of the population. Each year, more than 100,000 strokes are caused by an abnormal heart rhythms. So even if the ECG sensor is worthless to 99% of the people, it could end up saving lives.

And this is a big deal, assuming the sensor does not throw up many false positives! If that ends up being the case, as this article in Wired points out, the potential costs could outweigh the benefits. To this end, Apple has thrown out a warning.

“The ECG app is intended for over-the-counter (OTC) use. The ECG data displayed by the ECG app is intended for informational use only. The user is not intended to interpret or take clinical action based on the device output without consultation of a qualified healthcare professional. The ECG waveform is meant to supplement rhythm classification for the purposes of discriminating AFib from normal sinus rhythm and not intended to replace traditional methods of diagnosis or treatment.”

“The ECG app is not intended for use by people under 22 years old.”

The company has received clearance from the FDA for these measurements, the first of its kind. The US Food and Drug Administration (FDA) has recently launched a less restrictive regulatory framework for a number of pre-selected companies. This requires companies to submit less information when seeking market approval for a product. No doubt Apple has taken advantage of this fast-track approval process to register the technology.

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Further blurring the area further between a fitness tracker and medical device, the Apple watch will monitor your ticker in the background via the optical heart rate sensor and alert if it spots unusually high or low heart rate. This sensor will also do intermittent analysis of your heart rhythms and alert if it suspects atrial fibrillation. In essence, two separate sensors will be looking out for irregular heart rate rhythms.

“Apple Watch has become an intelligent guardian for your health,” said Apple CEO Tim Cook.

Its worth pointing out, the ECG app will not be available until later in 2018. That means at launch, the ECG feature will not be functional. Its also uncertain whether this functionality will extend beyond the US. While Apple has received the nod of approval from the FDA, its may not have the same from regulatory bodies in other countries. At launch, the company’s press release states “ECG functionality is US only”.

Currently Apple Watch’s UK, Canadan and Australian pages make no mention of the ECG sensor. If the functionality ends up being US only, it will make the Series 4 a much harder sell elsewhere. Our guess it will mirror the Apple Pay roll-out- a select number of countries first, gradually followed by others.

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