Hearty Patch is a completely open source, single-lead, ECG-HR wearable patch with HRV (Heart Rate Variability) analysis. It is based on the popular ESP32 system-on-a-chip. By using low-cost, highly-integrated components, we are able to keep the BOM’s cost low, while the simplicity of the circuit design means future expansion will be easier. Hearty Patch can be used both as a lifestyle device for managing fitness and stress as well as for diagnostics and medical research, with the potential for even more interesting applications.
Currently available low-cost, wearable heart monitors are usually based on less accurate optical measurements while the actual electrocardiography-based monitors are either too expensive or difficult to use. Similarly, heart-rate variability (HRV) data is used in fitness and training, but can also be used to detect some of the basic cardiac arrhythmias. Getting accurate R-R intervals for HRV studies is also tricky with most heart-rate monitors.
What is Heart-rate Variability?
Heart-rate variability, or HRV, is a measure of the variance of heart-rate in real-time. More specifically, it is the time difference between two R-R intervals (the signal peaks) in an electro-cardiogram (ECG or EKG) plot.
Studies of heart-rate variability have shown that HRV can be indicative of some common forms of arrhythmia, including atrial fibrillation (AF) and atrial tachycardia (AT), among others. HRV can be detected with a single lead ECG, like Hearty Patch, which, for cardiac patients being monitored for such forms of arrhythmia, is much easier to wear long term than a full Holter configuration (three or five leads).
In fitness applications, some high-performance athletes train using biofeedback for heart-rate control and also for knowing when to start and stop training (based on heart-rate).
HRV has also be known to reflect emotion, mood, anxiety, and stress. When such psychological events happen, there is a known pattern of variance in heart rate. This makes HRV useful tool for studying mood and managing stress in people who are prone to such psychological states.
Finally, since Hearty Patch can detect individual heart-beats in real-time, it can also be used in the areas of design and non-medical wearable’s to detect heart beats to activate lights or any other form of feedback. Cardio-biofeedback is an example of controlling heart-rate.
Who Needs Hearty Patch
- Medical professionals, caregivers, and researchers (for continuous event monitoring)
- High performance sports and fitness professionals (for precision cardio training)*
- Hardware/software developers (as a reference design)
- Curious people (because knowing your own heart-patterns is cool)
*Activities that cause sweating can prevent adhesive electrodes from adhering properly.
Hearty Patch Modes of Operation
Hearty Patch is open source. This means that the software on the device can be modified to work in any way you choose, providing access to raw heart-rate and inter-beat interval (IBI) data. Because of this flexibility, Hearty Patch can be operated in any or all of the following modes. * Continuous ECG streaming mode displays live ECG recording from the chest. This works similar to a heart-rate monitor. Below is a screen capture of the device working in ECG mode.
- Continuous ECG streaming mode displays live ECG recording from the chest. This works similar to a heart-rate monitor. Below is a screen capture of the device working in ECG mode.
- Beat-to-beat mode can be displayed by flashing the on-board LED or you can stream live, instantaneous heart rate over BLE for immediate detection of changes in inter-beat intervals.
- Arrhythmia detection mode runs the arrhythmia algorithm in real-time and detects events of AFIB.
- Heart-rate variability mode is available when Hearty Patch is connected to the desktop app, which displays the cardio-tachogram (CTG), Poincaré plot (variance), and histogram of inter-beat intervals. Below is a plot of data taken from an ECG simulator that is physically connected to the Hearty Patch.