A watch can send heart rate almost live and a short EKG after it finishes. A continuous EKG needs a chest strap or patch.
One minute on the TV
All four lanes show the same minute of the same person, sped up. Watch how differently each one fills in.
The watch saves it, and the phone sends it later
Apple, Galaxy or Pixel, during a set session
The person sits still with a finger on the watch
Worn on the body, connected to the TV
Today's wait depends on the phone. An Android phone sends every 15 to 30 minutes. An iPhone sends soon after new data, but only while it is unlocked.
Two different signals
The heart's signal has to pass through the body from one contact point to another. On a watch, the second point is your finger, so it only works while you hold it there.
This is the green light on the back of a watch. It works without you touching anything, which is why heart rate can run all the time. It shows the pulse, and it can't show the heart's electrical pattern.
How the data travels
Watch by watch
Recommended plan
One for Apple Watch and one for Wear OS, which covers Galaxy and Pixel. They send near live heart rate during check-ins or exercise sessions. Workout mode uses a lot of battery, so these are for set periods and won't run all day.
Their approval is the slow part, so it should start early. It is the only watch route to raw signals, and it would still give EKG spot readings, not a continuous stream.
A phone or the kiosk TV box can read one over Bluetooth. Android TV boxes can't, so those would go through the phone. A Polar H10 streams at 130 samples a second and is a good way to prove it, though it is a fitness product. Clinical use would need a medically cleared patch.
Before we promise this
Showing live heart data for patients, especially with alarms, could change how regulators classify SyncCare. We should get regulatory advice before offering this to hospitals.
Apple, Samsung and Google can change what apps may read, and some of what we found comes from older developer forums. We should confirm the details with each of them before committing.