It has been a while since apples release of the Apple Watch Series 4. But there have been significant strides in software, including the full access of ECG built in. ECG (Electrocardiogram) is the process of recording the electrical activity of the heart over a period of time using electrodes placed over the skin. The digital crown can detect such electrical activity and monitor it. Although, as a frequent user of this feature I will say it is extremely delicate and must be taken with a grain of salt. If you are sitting down, arm flush on a table and you are relaxed the results are stunning. I wouldn't recommend going for a jog and lazily placing your finger on the crown while standing up, it will probably think you are dying.
Along side the built in ECG it also is equipped with fall detection. If you take a spill hard enough the watch may prompt you to acknowledge that you are O.K. If you don't? it will then give you the option to SOS or contact emergency services. SOS is a feature you can setup in your health app in iOS to contact 1 or several contacts with a pre-loaded message. Something like - text mom, dad, and the wifey and tell them "I've fallen and I can't get up!"
The tech behind Apple Watch series 4 isn't anything to joke about, it is crazy good and, well, expensive. I get comments all the time about my watch and people literally drop their jaws when I tell them I paid $500 for mine. So it does come with a pretty penny, is it worth it though? I think if your intention is to equip a loved one with a heart condition or maybe some other medical condition and you also want to know their location, yeah 100% go for it. It's worth the money.