The Apple Watch is a device that is very focused on health thanks to its functionalities. One of these star functions is the possibility of doing electrocardiograms. In this article we explain everything you need to know about ECGs on Apple Watch in order to do them correctly.
What is an ECG
In order to understand the operation of this interesting function of the Apple Watch, you must first talk about what an ECG is. It can be summed up in that it is a routine medical study that provides information on the electrical impulses of the heart. In order for the heart muscle to function and beat, it receives electrical impulses from the sinus node . The electrocardiograph measures the impulses and represents them on a graph that, after being analyzed, gives valuable information about possible heart diseases.
In order to perform this measurement, the patient is always fitted with electrodes on selected body parts. These will be in charge of measuring the electrical impulses of the heart.
ECG operation on Apple Watch
Standard ECGs performed at a doctor’s office have a total of 12 leads. This means that signals are recorded from different angles in order to provide much more accurate information. In the case of the Apple Watch we do not have 12 leads , since having only one electrode can perform 1-lead electrocardiograms .
From the Apple Watch Series 4 onward, the company introduced two electrode in its watches. One of them is next to the cardiac sensor and is a circular black crystal. The second is in the digital crown that you will find on the side of the Apple Watch. In order to perform an ECG, you simply have to rest your finger on the digital crown to be able to create a closed circuit between your heart and the two arms in order to register the electrical impulses of the chest.
Apple Watch ECG limitations
The Apple Watch because it only has one derivation is quite limited. It is only capable of detecting irregular heart rhythms and atrial fibrillation (AF). And these two tasks are performed wonderfully, since different studies that Apple has carried out show that the results of a medical electrocardiograph and that of the Apple Watch are very similar to detect irregular rhythm and atrial fibrillation. Specifically, 98.3% sensitivity was recorded in the evaluation of atrial fibrillation in the evaluable results.
By only recording atrial fibrillation and irregular rhythms, Apple Watch is not able to detect any of these diseases:
- Myocardial infarction
- Cardiovascular accident or venous thrombosis.
- Different types of arrhythmia.
In other words, the result produced by the watch is completely indicative and a medical professional should always be consulted if any type of severe clinical pathology occurs.
Requirements to do an ECG
Please note that this functionality is only available on Apple Watch Series 4 or later. These are the only ones that integrate the electrodes necessary to perform a lead electrocardiogram. From Apple they also report that this function is only recommended for people over 22 years old . To make this recommendation, they are based on the studies they have done since the sample of users did not include younger people of this age.
It is also important to note that the application to perform these electrocardiograms is not available in all countries. This is because approval by state health authorities is required. This process takes time and it is possible that in your country it is not yet available and the application to measure it may not appear on your Apple Watch.
How to do an EKG on Apple Watch
At any time you can do an ECG with the Apple Watch, although the common thing is to do it when you have symptoms or receive a notification of irregular rhythm. To do the electrocardiogram you must follow the following steps:
- Open the ECG app on Apple Watch.
- Rest your arms on the table or in your lap.
- Place the finger of the opposite hand on the digital crown and hold it without pressing it.
- Hold this position for 30 seconds.
- Write down the symptoms you are presenting and click on ‘Save’.
Interpret results
The results that you will get when you do an ECG can be summarized as follows:
- Sinus rhythm : The most common result indicating that your heart follows a uniform pattern between 50 and 100 BPM. But obviously if you have symptoms, you should go to a doctor since it can come out normal and feel bad.
- Atrial fibrillation : In this case the heart beats in an irregular pattern with a frequency between 50 and 120 LPM.
- High or low heart rate: when the heart rate is below 60 LPM it is considered bradycardia and when it is above 120 LPM it is called tachycardia. This may be due to taking some type of medication or physical effort and / or stress in the case of tachycardia.
- Inconclusive: in this case the record cannot be evaluated. It could be because you have a pacemaker or the registry has a type of arrhythmia or condition that the app cannot detect.
But obviously these results must be interpreted by a medical specialist. If you have any type of symptoms, the ECG application serves as an orientation, but you should always go to a medical service to check with medical equipment that can diagnose more accurately.