AU2018286621A1 - HeartMonitor: An intergrated home-based and mobile Heart Attack Monitor and alert system. - Google Patents

Abstract

: Heart attacks are one of the most common heart problems and happen very quickly. It is very important that people with a high risk of a heart attack be provided with devices that alert emergency services and family/friends on behalf of the potentially confused and in pain or unconscious person. A heart monitoring app was coded to read the output of an electrode based heart monitor vest and display a simple ECG on an Android phone. The app recognises when the heart stops (flat line) or goes into ventricular fibrillation (weak irregular electrical activity), and notifies the ambulance service (000), family and friends by Bluetooth connected to the Android phone with the GPS location of the person having the heart attack. The device and app will allow people with a high risk of heart attacks to live at home or move freely instead of having to be in a hospital.

Description

TITLE: HeartMonitor: An intergrated home-based and mobile Heart Attack Monitor and alert system.

TECHNICAL FIELD: Biomedical Engineering

BACKGROUND:

[0001] The heart is the most vital organ in the human body. It is the pump that keeps blood flowing to all parts of the body, ensuring that sufficient amounts of oxygen and nutrients are distributed and present. When the heart is malfunctioning or stops, it is crucial that the victim is taken to hospital as soon as possible. There are many people at risk of suffering a heart attack. However, symptoms of a heart attack are often misinterpreted by the patient or others as muscle pains or flu. In other cases, there is no one with the victim to administer CPR and even so, there is not always a defibrillator at hand, leaving a very small chance of survival. For these reasons, medical intervention is often administered too late.

[0002] A heart attack occurs when there is a disruption in blood flow due to coronary arteries being blocked with plaque. Eventually the plaque tears open and red cells stick onto it, further narrowing the already blocked artery. This causes a significant decrease in blood flow and therefore forces heart muscle to work harder on pumping blood. Whilst doing this, the heart muscles are under a lot of stress as the lack of blood flow limits their supply of oxygen. The oxygen-starved cells send pain signals to the brain. As a result of this and nerve-pathway merges, the brain may get confused and pick these up as pain signals coming from another part of the body, such as the arms. This is why patients often feel pain from body parts seemingly unrelated to the heart during a heart attack. Escalating pain signals from the heart confuse the brain furthermore.

[0003] The body's 'Fight or Flight' response is then enabled, releasing adrenaline into the bloodstream which drives the heart muscle to work harder than it is already struggling to do so. Eventually, a patch of heart muscle becomes so weak that it stops functioning. Soon the clot brings the blood flow to stop. As the heart weakens, blood flows back into the lungs where liquid is forced out of it and into the lung sacs, causing breathing difficulties and raising the chances of the victim drowning in their own bodily fluid.

[0004] The lack of oxygen eventually affects the brain as well, resulting in dizziness and disorientation. By this stage, irreplaceable heart cells are lost at a deadly rate of 500 cells per second. When connected to an ECG (Electrocardiogram), measuring the heart's electrical activity, the readings can be analysed to find the location of the dying heart muscle. TPA (Tissue Plasminogen Activator) is administered to unblock the clot and must reach it before too many heart cells die and the heart stops. If successful, the TPA dissolves and tears through the clot and unblocks the artery, allowing for blood to flow freely again. In saying that, if this doesn't happen in time, the heart stops and the patient does not survive (Lorraine, 2010).

[0005] This entire process of a heart attack happens very quickly, which is why it is very important that people with a high risk of a heart attack be provided with devices that alert emergency services and family/friends on behalf of the potentially confused and in pain or unconscious person.

SUMMARY:

[0006] Issues currently encountered without an appropriate solution include: patients calling at the very last minute to receive help due to misinterpretation, ergo not getting that help quick enough; and elderly patients not being able to alert anyone themselves in the case of a heart attack. As mentioned earlier, the whole process of a heart attack can happen within a matter of minutes. Therefore, any delay in getting the victim to the hospital is critical. "It is estimated 350,000 Australians have had a heart attack at some time in their lives." (The Heart Foundation, 2017) Nonetheless, a great portion of these patients are taken to hospital too late, resulting in reduced recovery or death.

[0007] Provided an appropriate solution, such as this one, patients and their friends and family will be more confident to continue about their daily life without the worry of not receiving help on time if they have a heart attack. By cutting through human intervention, and alerting the ambulance as soon as possible, more patients will be able to be treated faster, potentially saving their lives.

[0008] To effectively work as a heart monitoring system and respond to emergency situations, the vest, device and app must have the following features: * Accurate measurement of the heart's electrical activity * Strong reliable connection and communication between each component • Cheap to make whilst being able to reliably fulfil its purpose * Able to be worn for long periods of time

[0009] These became the aims for this project. To complete this task, three sub-projects were integrated into creating a heart monitoring system that responds to emergency situations. These were the: * Electrode Vest * Arduino, Heart Rate Monitor and Bluetooth Module Device * Heart Monitor App

[0010] A heart monitoring app was coded to read the output of an electrode based heart monitor vest and display a simple ECG on an Android phone. The app recognises when the heart stops (flat line) or goes into ventricular fibrillation (weak irregular electrical activity), and notifies the ambulance service (000), family and friends by Bluetooth connected to the Android phone with the GPS location of the person who is having the heart attack. The device and app will allow people with a high risk of heart attacks to live at home or move freely instead of having to be in a hospital.

DESCRIPTION OF EMBODIMENTS:

[0011] Originally it was planned to purchase a cycling vest or other skin-fitting garment and then cut out holes for the electrodes. This plan had the electrode cables running through the vest, rather than hanging loose. It also had the Arduino, Bluetooth and AD8232 Heart Monitor Boards (ECG reader) in the inner breast pocket. This plan would have required a fair bit of cutting and sewing, therefore an alternative solution was sought after. After searching for a garment ideal for this project, the Care Vest - Conductive Garment Electrode Vest was found and bought. This vest is designed to hold electrodes in place, therefore fitting the requirements of this project. Although the final design was not the same as the original, they are very similar. It was also intended to use dry electrodes, but after much testing, much cheaper and more effective wet electrodes were fitted to the vest.

[0012] Electrodes were placed in the inside of the vest in the holes corresponding to the positioning available at https://learn.sparkfun.com/tutorials/ad8232-heart-rate-monitor hookup-guide From the other side of the jacket, appropriate wires were attached to their corresponding electrodes.

[0013] Prior to purchasing the Care Vest, it was planned to place the electrodes at the front side of the victim's chest as practiced with Resting ECGs. However, the holes in the Care Vest were at the back. This affected the reading of the Electrode Vest and therefore, a late modification to the vest gave the option of placing the electrodes on the chest or the back. The chest placement provided a stronger and steadier signal.

[0014] Code from https://github.com/sparkfun/AD8232 Heart Rate Monitor/blob/master/Software/Heart Rate Display Arduino/Heart Rate Display Arduino.ino was copied onto the Arduino via a program called "Arduino Create" to allow it to translate signals from the AD8232 Heart Rate Monitor. In addition to this was coding which allowed the Arduino to connect to the Bluetooth Module was added using the serial port.

[0015] The Arduino Compatible Bluetooth Wireless Module connected to the Arduino Mega 2560 board. Instructions for this setup are available at https://www.olimex.com/Products/Components/RF/BLUETOOTH-SERIAL-HC 06/resources/hcO6.pdf and http://www.egr.msu.edu/classes/ece480/capstone/spring14/group01/docs/appnote/Wirsing SendingAndReceivingDataViaBluetoothWithAnAndroidDevice.pdf

[0016] Five male-to-male straight break away headers were soldered to pin holes GND, 3.3v, OUTPUT, LO- and LO+ on the AD8232 Heart Rate Monitor. The long end of the soldered pins were connected to separate rows on the bread board.One side of five male-to-male jumper wires were each connected to the individual rows of the pins already on the bread board. Following pin connections available at https://leam.sparkfun.com/tutorials/ad8232-heart rate-monitor-hookup-guide, the male-to-male jumper wires were connected to their corresponding places on the Arduino Board.

[0017] The Electrode Vest was put on the patient, the cable from the electrodes on the Electrode Vest was attached to the AD8232 board through its corresponding jack port. The battery pack was connected to the Arduino through the power input port.

[0018] Throughout making the device, a number of issues were encountered. The main issue was soldering male-to-male straight break away headers onto the AD8232 Heart Monitor board. Upon soldering these pins on, the board fried. A possible explanation for this may have been simple soldering errors where the iron came into direct contact with the board. However, it was also suspected that the board was highly sensitive to the heat emitted from the soldering iron without direct contact, and was damaged.

[0018] Another issue was the Bluetooth connection. The original board used for this was the Bluetooth Shield 4.0 for Arduino. For a couple of months, the board refused to communicate with other hardware and software. It was later found that this issue was due to the fact that the board was a Bluetooth Low Energy (BLE) board. The code already copied and typed up for the Arduino and the Heart Monitor app was for a normal Bluetooth system, however, using the BLE board required an entirely different set of code. The two options to go forward were to either change all of the code to suit the BLE board, or to buy a new normal Bluetooth board. Therefore, due to time restrictions, the Arduino Compatible Bluetooth Wireless Module was bought. This board is not a BLE board.

[0019] Code was copied from https://github.com/sparkfun/AD8232 Heart Rate Monitor/blob/master/Software/Heart Rate Display Processing/Heart Rate Display/Heart Rate Display.pde onto Eclipse Oxygen, allowing the app to process a sketch of the analog values from the Arduino, Heart Rate Monitor and Bluetooth Module Device. Additional coding was written into the program to add graphics and enable features such as: alerting a provided number in the case of a flat line, adding in an emergency contact and making manual calls to said contact. More code was written/copied onto the program regarding Bluetooth, to allow the device to communicate with the electronic components. The program was run by the Android studio and made an app that could be installed on an Android phone.

[0020] As previously stated, the app is able to pick up ventricular fibrillation and make the emergency call accordingly. There are two kinds of fibrillation: atrial fibrillation and ventricular fibrillation. Atrial fibrillation concerns fibrillation occurring in the heart's atria, the upper two chambers. These chambers stop pumping blood and may eventually lead to blood clot, organ damage and strokes. Atrial fibrillation is not an arrhythmia that puts the person suffering it in an instant life-threatening situation.

[0021] Ventricular fibrillation relates to fibrillation occurring in the ventricles, the heart's lower two chambers. Unlike atrial fibrillation, ventricular fibrillation is instantly life threatening as it causes the ventricles to "contract in a rapid, unsynchronized way."(Heart.org, 2017) This may lead to little spurts of blood pumping out of the ventricles, however, the blood flow back into the body is ultimately disrupted. Unlike atrial fibrillation, the blood must travel upwards, therefore due to gravity, the blood is not able to at least passively flow. Ventricular fibrillation associates with heart attacks as they are likely to occur when not enough oxygen is being received by heart muscle or when heart muscle is damaged. That is, as the heart attack worsens, blood flow is obstructed and therefore slowing it. In this emergency situation, the heart begins to pump frantically but weakly, essentially wearing itself out. This is done whilst it is receiving minimal oxygen. Both these factors add up to ventricular fibrillation.

[0022] As ventricular fibrillation occurs, the ECG display is almost at flatline. That is, there are very short and sharp fluctuations which appear in a zigzag shape. This allows for two boundaries to be set. A maximum and a minimum. The app is programmed so that if the readings remain between these parameters for a particular amount of time, it will make the automatic emergency call. A cardiologist was contacted regarding what these parameters should be and how long is it safe to wait and see whether the ventricular fibrillation reading was due to an error (eg. machine malfunction or an electrode coming off). Despite being told they must be very specific to be of any clinical use, a specific answer was not given for the parameters nor time. Nonetheless, this problem was easily worked around because the app's parameters to detect ventricular fibrillation and the time waited until it confirms it as an emergency situation are all variables that can be changed in the code within a minute. In saying this, it is greatly acknowledged that these values are essential and must be precise in order to work effectively. However, despite asking, an answer was not found for unknown reasons. With further questioning from other health professionals and cardiologists, an answer will be found to add into these gaps.

[0023] As an example of how the app could be programmed, a steady electrical activity in milliVolts of between 250mV and 350mV would be defined as ventricular fibrillation or flatlining (the threshold is adjustable).

[0024] It was also decided to include a major safety feature so that a disconnected electrode would not be interpreted as a patient having a heart attack. If an electrode disconnects the screen will display a red flat line with an exclamation mark at the bottom of the screen to alert the patient but does not send out a signal.

[0025] As it stands, the HeartMonitor app successfully opens on an Android phone and is able to communicate with the device via both Bluetooth and serial connection. As hypothesised, the Electrode Vest picks up ECG signals from the person wearing it, the Arduino, Heart Rate Monitor and Bluetooth Module Device. Upon opening the HeartMonitor app, a message box is displayed for the app to gain permission to turn on the mobile device's Bluetooth and location settings so that it can connect to the app. Users can manually add in an emergency contact number that will be saved on the mobile device even after the battery has been taken out and put back in.

[0026] In a situation where the user needs to make a manual call urgently, they are able to do so by pushing the "EMERGENCY CALL" button and a box will pop up. This allows the user to proceed with sending their alert or cancel if they weren't meant to push the button. The emergency alert is a text, but the app could easily be modified to include a recorded call. Upon sending the alert, the app confirms this process.

[0027] This heart monitor and app has the potential to benefit not only the wider Canberra community but also Australia generally. The sooner that medical attention can get to a person having a heart attack, the higher their chance of survival. Every year around 55 000 Australians suffer from a heart attack and from this amount, around 9000 die from the attack. That means that every 10 minutes someone suffers a heart attack and every 60 minutes a heart attack claims a life. The Heart Foundation themselves say "Too many people die from heart attack because they take too long to call an ambulance" (The HeartFoundation, 2017).

CITATION LIST:

Heart Foundation. (2017). Heart attack symptoms. [online] Available at: https://www.heartfoundation.org.au/your-heart/heart-attack-symptoms [Accessed 31 Dec. 2018].

Heart.org. (2017). VentricularFibrillation.[online] Available at: http://www.heart.org/HEARTORG/Conditions/Arrhythmia/AboutArrhythmia/Ventricular Fibrillation UCM 324063 Article.jsp#.WdtY GiCyiM [Accessed 31 Dec. 2018].

Lorraine, A. (2010). What happens during a HeartAttack?. [video] Available at: https://www.youtube.com/watch?v--H VsHmoRQKk [Accessed 31 Dec. 2018].

Claims (7)

1. CLAIMS: 1. A heart monitoring app coded to read the output of an electrode based heart monitor vest and display a simple ECG on an Android phone. The app recognises when the heart stops (flat line) or goes into ventricular fibrillation (weak irregular electrical activity), and notifies the ambulance service (000), family and friends by Bluetooth connected to the Android phone with the GPS location of the person who is having the heart attack. The device and app will allow people with a high risk of heart attacks to live at home or move freely instead of having to be in a hospital.
2. 2. The vest in claim 1 has electrodes fixed in specific positions to allow optimal readings of the heart's electrical activity.
3. 3. The vest in claim 1 has a zip opening at the front allowing for patient to put on and take off vest by themselves.
4. 4. The app in claim 1 displays a basic ECG reading on the mobile screen.
5. 5. In case of the need to manually call emergency services(OOO), the app in claim 1 has a button to do so.
6. 6. The app in claim 1 can save multiple emergency contact numbers in addition to emergency services(OOO).
7. 7. The app in claim 1 detects ventricular fibrillation such that if the readings remain between certain parameters for a particular amount of time, it will make the automatic emergency call.