How does the watch detect your heart rate, electrocardiogram? Are these results accurate enough?

Heart rate refers to the number of heartbeats per minute. The normal range of heart rate for a normal person is 60-100 beats per minute in a quiet and awake condition.Heart rate auscultation to understand the heart rate, the strength of the heart rate and other heart beating conditions.

The electrocardiogram mainly reflects the electrical activity of the heart, so it has a very positive value for the diagnosis and analysis of various arrhythmias and conduction disorders.

Heart rate and electrocardiogram are two completely different concepts, heart rate refers to the frequency of the heart beating. An electrocardiogram is a test that reflects electrical changes in the heart.

Heart rate can be obtained from electrocardiogram, but not necessarily from electrocardiogram, but also from heart sound, pulse, etc. The frequency of the heartbeat, also known as the heart rate, can be obtained from an electrocardiogram. In addition to knowing the heart rate, an ECG can also understand the rhythm of the heartbeat,  and find out if there are other heart problems.

In general, the principle of optics is used to monitor, which is called PPG. We all know that blood is red, so it reflects red light and absorbs green light. Blood contains heme, and heme with different oxygen levels absorbs and reflects light differently. The blood flow in the arteries also changes periodically with the systole and diastole of the heart. The LED light behind the watch will flash hundreds of times per second, and the number of heartbeats per minute, which is the heart rate, is calculated according to the intensity of the reflected light.

An electrocardiogram records electrical signals from the heart through wires placed at various locations on the body. Due to the different electrical signal strengths of different parts of the body, the more points are usually arranged, the more accurate the measurement will be. In hospitals, this number is generally 10 or 12. At present, most smart watches with ECG function use the metal on the side and a layer of material covered on the back of the fuselage to detect the electrical signals of the fingertip and wrist respectively. That is, the monitoring of a single site, the information obtained from the results is very limited.

We should correctly understand that the single-lead ECG on smart watches has limitations, but its role is far greater than a "placebo", and it has great reference value for patients and doctors. Considering the existence of patients with paroxysmal atrial fibrillation, even if the data of the smart watch is not accurate enough, because it is more portable, it only takes 30 seconds to complete a measurement by raising the wrist at any time, which is suitable for the elderly and heart disease patients. It is said that portable ECG smart wearable devices are very necessary and can play a role in warning and avoiding risks.