Homemade electrocardiograph (ECG). ECG of the heart Preparation for taking an ECG

An important skill for a nurse is the correct ECG technique(electrocardiograms). Let us remind you that electrocardiography is a technique for recording the electrical fields of the heart that arise during its activity. as well as obtaining their graphic representation on paper or display. Electrocardiography is an informative and non-invasive method for studying the functioning of the heart - convenient and valuable for the patient and the attending physician.

Electrocardiogram is a graphic image in the form of a curve obtained during electrocardiography on paper or a display. ECG recording is carried out using devices called electrocardiographs. Any electrocardiograph has:

• input device;
• heart biopotential enhancer;
• recording device.

A nurse is allowed to work with an electrocardiograph only after training, preferably in the ““ specialization. ECG registration is carried out in a specially adapted and equipped room, as well as in the ward at the patient’s bedside, at home, at the point of medical care, or in an ambulance.

The ECG room should be located away from any suspected sources of electrical noise. It is advisable to shield the couch: it is covered with a special blanket with a sewn grounded (!) metal mesh.

ECG technique: algorithm

Immediately before the scheduled registration of an ECG, the patient should not eat, smoke, drink stimulating drinks (tea, coffee, energy drinks), or exert any physical stress on the body.

We record in the necessary documentation the patient’s personal data, medical history number, date and time of the ECG.

We place the patient on the couch in a supine position. We degrease those areas of the skin where we will apply the electrodes - wipe them with a napkin soaked in an isotonic solution of sodium chloride (0.9%).

We apply electrodes: 4 plate electrodes - on the lower thirds of the inner surface of the legs and forearms, and on the chest - chest electrodes equipped with suction cups. For single-channel recording, 1 chest electrode is used, for multi-channel recording, several are used.

We connect wires of a certain color coming from the electrocardiograph to each electrode. Common markings for electrocardiograph wires:

• red - right hand;
• yellow - left hand;
• green - left leg;
• black - right leg (patient grounding);
• white - chest electrode.

When recording an ECG in 6 chest leads in the presence of a six-channel electrocardiograph, use the following tip markings:

• red - for connection to electrode V1;
• yellow - to V2;
• green to V3;
• brown - to V4;
• black - to V5;
• blue or purple - to V6.

Most often, the ECG is recorded in 12 leads:

• 3 standard (bipolar) leads (I, II, III);
• 3 reinforced unipolar leads;
• 6 chest leads.

Standard (bipolar) ECG leads

Registration of standard limb leads is carried out by connecting electrodes in pairs:

• I standard lead - left hand (+) and right hand (-);
• II standard lead - left leg (+) and right arm (-);
• III standard lead - left leg (+) and left leg (-).

Electrodes are applied to the left arm, right arm and left leg (see markings in the figure). A 4th electrode is placed on the right leg to connect to the ground wire.

Formation of three standard electrocardiographic leads from the limbs. Below is Einthoven’s triangle, each side of which is the axis of one or another standard lead

Reinforced unipolar limb leads

Unipolar leads are characterized by the presence of only one active - positive - electrode, the negative electrode is indifferent and represents a “combined Golberg electrode”, which is formed when two limbs are connected through additional resistance.

Reinforced unipolar leads have the following designations:

• aVR—right arm abduction;
• aVL - from the left hand;
• aVF - from the left leg.

Formation of three reinforced unipolar limb leads. Below is Einthoven’s triangle and the location of the axes of three reinforced unipolar limb leads.

Chest leads

The chest leads in the ECG are unipolar. The active electrode is connected to the positive pole of the electrocardiograph, and the triple indifferent electrode combined from the limbs is connected to the negative pole of the device. The chest leads are usually designated by the letter V:

• V1 - the active electrode is placed in the IV intercostal space at the right edge of the sternum;
• V2 - in the IV intercostal space at the left edge of the sternum;
• V3 - between the IV and V intercostal spaces along the left parasternal line;
• V4 - in the 5th intercostal space along the left midclavicular line;
• V5 - in the 5th intercostal space along the anterior axillary line;
• V6 - and V intercostal space along the midaxillary line.

Selecting the electrocardiograph gain

When selecting the gain of each channel of the electrocardiograph, it is necessary that a voltage of 1 mV causes a deflection of the galvanometer and recording system of 10 mm. In the “0” position of the lead switch, the gain of the device is adjusted and the calibration millivolt is recorded. If the amplitude of the teeth is too large (1 mV = 5 mm), you can reduce the gain; if it is small (1 mV = 15-20 mm), you can increase it.

ECG registration

An electrocardiogram is recorded while the patient is breathing quietly. First - in standard leads I, II, III, then - in reinforced unipolar leads from the limbs (aVR, aVL, aVF), then - in chest leads V1. V2, V3, V4, V5, V6. At least 4 cardiac cycles should be recorded in each lead.

As can be concluded from the above, with the necessary knowledge and skills ECG technique should not present any difficulties for the nurse. We invite you to watch the video to reinforce what you have read.

The heart is the most important organ in the human body. It is often compared to a motor, which is not surprising, because the main one is the constant pumping of blood in the vessels of our body. The heart works 24 hours a day! But it happens that it cannot cope with its functions due to illness. Of course, it is necessary to monitor general health, including heart health, but in our time this is not always possible for everyone.

A little history about the appearance of the ECG

Back in the mid-19th century, doctors began to think about how to track work, identify deviations in time and prevent the terrible consequences of the functioning of a diseased heart. Already at that time, doctors discovered what was happening in the contracting heart muscle and began to conduct the first observations and studies on animals. Scientists from Europe began to work on creating a special device or a unique technique for monitoring and finally the world's first electrocardiograph was created. All this time, science has not stood still, so in the modern world they use this unique and already improved device, which produces so-called electrocardiography, also called ECG for short. This method of recording heart biocurrents will be discussed in the article.

ECG procedure

Today, this is an absolutely painless procedure that is accessible to everyone. An ECG can be done in almost any medical facility. Consult your family doctor and he will tell you in detail why this procedure is necessary, how to take an ECG and where it can be done in your city.

Short description

Let's look at the steps of how to take an ECG. The algorithm of actions is as follows:

1. Preparing the patient for future manipulation. Laying him down on the couch, the health care worker asks him to relax and not tense up. Remove all unnecessary items, if any, that may interfere with the cardiograph recording. Free the necessary areas of skin from clothing.
2. They begin to apply electrodes strictly in a certain sequence and order of application of electrodes.
3. Connect the device to work while observing all the rules.
4. Once the device is connected and ready to use, start recording.
5. A paper with a recorded electrocardiogram of the heart is removed.
6. The ECG result is handed over to the patient or doctor for subsequent interpretation.

Preparing for an ECG

Before you learn how to take an ECG, let's consider what steps you need to take to prepare the patient.

An ECG machine is available in every medical facility; it is located in a separate room with a couch for the convenience of the patient and medical staff. The room should be bright and cozy, with an air temperature of +22...+24 degrees Celsius. Since it is possible to correctly take an ECG only if the patient is completely calm, such an environment is very important for carrying out this manipulation.

The subject is placed on a medical couch. In a lying position, the body easily relaxes, which is important for future cardiograph recordings and for assessing the work of the heart itself. Before applying ECG electrodes, a cotton swab moistened with medical alcohol must be used to treat the desired areas of the patient’s arms and legs. Re-treatment of these areas is carried out with saline solution or a special medical gel intended for these purposes. The patient must remain calm during the cardiograph recording, breathe evenly, moderately, and not worry.

How to take an ECG correctly: applying electrodes

You need to know in what order the electrodes need to be applied. For the convenience of the personnel performing this manipulation, the inventors of the ECG device defined 4 colors for the electrodes: red, yellow, green and black. They are applied in exactly this order and in no other way, otherwise conducting an ECG will not be advisable. It is simply unacceptable to confuse them. Therefore, medical personnel who work with an ECG device undergo special training, then pass an exam and receive an admission or certificate that allows them to work specifically with this device. The health worker in the ECG room, according to his work instructions, must clearly know the location of the electrodes and correctly perform the sequence.

So, the electrodes for the arms and legs look like large clamps, but don’t worry, the clamp is placed on the limb absolutely painlessly, these clamps are of different colors and are applied to certain places on the body as follows:

• Red - right wrist.
• Yellow - left wrist.
• Green - left leg.
• Black - right leg.

Application of chest electrodes

Nowadays, chest electrodes come in different types, it all depends on the manufacturer. They are disposable and reusable. Disposable ones are more convenient to use and do not leave unpleasant traces of irritation on the skin after removal. But if there are no disposable ones, then reusable ones are used; they are similar in shape to hemispheres and tend to stick. This property is necessary for clear placement in exactly the right place with subsequent fixation for the right time.

A medical professional, who already knows how to take an ECG, sits on the couch to the right of the patient in order to correctly apply the electrodes. It is necessary, as already mentioned, to pre-treat the patient’s chest skin with alcohol, then with saline solution or medical gel. Each chest electrode is marked. To make it clearer how to take an ECG, a diagram of the application of electrodes is presented below.

Let's begin applying electrodes to the chest:

1. First, we find the patient’s 4th rib and place the first electrode under the rib, which has the number 1 on it. In order for the electrode to successfully position itself in the required place, you need to use its suction property.
2. We also place the 2nd electrode under the 4th rib, only on the left side.
3. Then we proceed to applying not the 3rd, but the 4th electrode at once. It is placed under the 5th rib.
4. Electrode number 3 must be placed between the 2nd and 4th ribs.
5. The 5th electrode is installed on the 5th rib.
6. We place the 6th electrode at the same level as the 5th, but a couple of centimeters closer to the couch.

Before turning on the device for recording an ECG, we once again check the correctness and reliability of the applied electrodes. Only after this can you turn on the electrocardiograph. Before this, you need to set the paper speed and configure other indicators. During recording, the patient must be in a state of complete rest! At the end of the operation of the device, you can remove the paper with the cardiograph record and release the patient.

We take ECGs for children

Since there are no age restrictions for performing an ECG, ECGs can also be taken for children. This procedure is done in the same way as for adults, starting at any age, including (as a rule, at such an early age, an ECG is done solely to eliminate suspicion of heart disease).

The only difference between how to take an ECG for an adult and a child is that a child needs a special approach, everything needs to be explained and shown to him, and reassured if necessary. The electrodes on the child’s body are fixed in the same places as on adults, and must correspond to the child’s age. You have already learned how to apply ECG electrodes to the body. In order not to upset the little patient, it is important to ensure that the child does not move during the procedure, support him in every possible way and explain everything that is happening.

Very often, when prescribing pediatricians, they recommend additional tests, with physical activity or with the prescription of a particular drug. These tests are carried out in order to promptly identify abnormalities in the functioning of the child’s heart, correctly diagnose a particular heart disease, prescribe treatment in a timely manner, or dispel the fears of parents and doctors.

How to take an ECG. Scheme

In order to correctly read the recording on the paper tape that the ECG machine gives us at the end of the procedure, of course, it is necessary to have a medical education. The record must be carefully studied by a general practitioner or cardiologist in order to promptly and accurately diagnose the patient. So, what can an incomprehensible curved line, consisting of teeth, individual segments at intervals, tell us? Let's try to figure this out.

The recording will analyze how regular the heart contractions are, identifying the heart rate, the source of excitation, the conductive ability of the heart muscle, the determination of the heart in relation to the axes, and the condition of the so-called cardiac waves in medicine.

Immediately after reading the cardiogram, an experienced doctor will be able to make a diagnosis and prescribe treatment or give the necessary recommendations, which will significantly speed up the recovery process or protect against serious complications, and most importantly, a timely ECG can save a person’s life.

It is necessary to take into account that the cardiogram of an adult differs from the cardiogram of a child or a pregnant woman.

Is ECG taken for pregnant women?

In what cases is a pregnant woman prescribed a heart electrocardiogram? If at the next appointment with an obstetrician-gynecologist the patient complains of chest pain, shortness of breath, large fluctuations in blood pressure control, headaches, fainting, dizziness, then most likely an experienced doctor will prescribe this procedure in order to promptly reject bad suspicions and avoid unpleasant consequences for the health of the expectant mother and her baby. There are no contraindications for undergoing an ECG during pregnancy.

Some recommendations before the planned ECG procedure

Before taking an ECG, the patient must be instructed about what conditions need to be met the day before and on the day of removal.

• The day before, it is recommended to avoid nervous tension, and the duration of sleep should be at least 8 hours.
• On the day of delivery, you need a small breakfast of food that is easily digestible; a prerequisite is not to overeat.
• Eliminate foods that affect heart function for 1 day, such as strong coffee or tea, spicy seasonings, alcoholic drinks, and smoking.
• Do not apply creams and lotions to the skin of the arms, legs, chest, the action of fatty acids can subsequently worsen the conductivity of the medical gel on the skin before applying the electrodes.
• Absolute calm is necessary before taking an ECG and during the procedure itself.
• Be sure to avoid physical activity on the day of the procedure.
• Before the procedure itself, you need to sit quietly for about 15-20 minutes, breathing calmly and evenly.

If the subject has severe shortness of breath, then he needs to undergo an ECG not lying down, but sitting, since it is in this position of the body that the device will be able to clearly record cardiac arrhythmia.

Of course, there are conditions in which it is absolutely impossible to perform an ECG, namely:

• In acute myocardial infarction.
• Unstable angina.
• Heart failure.
• Some types of arrhythmia of unknown etiology.
• Severe forms of aortic stenosis.
• PE syndrome (pulmonary embolism).
• Dissection of aortic aneurysm.
• Acute inflammatory diseases of the heart muscle and pericardial muscles.
• Severe infectious diseases.
• Severe mental illness.

ECG with mirror arrangement of internal organs

The mirror arrangement of the internal organs implies their arrangement in a different order, when the heart is not on the left, but on the right. The same applies to other organs. This is a fairly rare phenomenon, but nevertheless it occurs. When a patient with a mirror arrangement of internal organs is prescribed to undergo an ECG, he must warn the nurse who will perform this procedure about his peculiarity. In this case, young specialists working with people with mirror arrangement of internal organs have a question: how to take an ECG? On the right (the removal algorithm is basically the same), the electrodes are placed on the body in the same order as in ordinary patients they would be placed on the left.

Take care of your health and the health of your loved ones!

In terms of its versatility, information content and accessibility, ECG occupies one of the leading positions among instrumental examination methods. Any health worker must know the basics of an ECG, and he must also know the technique of taking an ECG. After all, the result of the study depends on the ability to correctly apply electrodes and take a cardiogram. Proper recording of an ECG and compliance with the algorithm for taking a cardiogram is the first step towards making the correct diagnosis. Let's consider what the ECG technique includes, how preparation for the procedure should be carried out, and what the algorithm of actions is.

1 Algorithm of actions

The technique of taking an ECG is one of the practical skills that every student of a medical college and university has. And if a student has not mastered this technique, he will not be familiar with medicine. It is not for nothing that medical staff are carefully trained in this manipulation, because in emergency situations, recording an ECG and the ability to decipher a cardiogram can save the patient’s life. The ECG registration algorithm is extremely simple at first glance, but it has its own nuances, without knowledge of which the manipulation will not succeed.

The ECG registration scheme is as follows:

1. Preparation for the procedure,
2. Application of electrodes,
3. Recording on tape.

Let's look at these three points in more detail.

2 Preparing for an ECG

1. The patient must remain calm during the ECG recording. You should not worry, be nervous, or experience excessively strong emotions. Breathing should be smooth and not rapid. If the patient experiences excitement or anxiety, the doctor must reassure the patient and explain the safety and painlessness of the manipulation. 10-15 minutes before taking the cardiogram, it is advisable to sit, adapt to the functional diagnostics room and medical staff, and restore breathing.
2. Preparation for an ECG excludes smoking, drinking alcoholic and caffeinated drinks, strong tea, and coffee before the procedure. Smoking and caffeine stimulate the heart, which may cause the ECG reading to be unreliable.
3. It is not recommended to eat 1.5-2 hours before the procedure, and it is better to conduct an ECG on an empty stomach.
4. After taking a morning shower on the day the cardiogram is taken, it is not advisable for the patient to apply oil-based creams and lotions to the body. This may create some obstacle to good contact between the electrodes and the skin.
5. The patient's clothing should be comfortable and loose, so that it is possible to freely expose the hands and ankles, and quickly remove or unbutton clothes to the waist.
6. There should be no metal jewelry, chains, or bracelets on the chest and limbs.

3 Application of electrodes

The patient takes a horizontal position on the couch with a bare torso, ankle and wrist joints free from clothing. After which the medical worker begins to apply electrodes. Limb electrodes in the form of plates with a screw are applied to the lower surface of the forearms and shins in a strictly established clockwise order. The electrode of each limb has its own color: Red - right hand, Yellow - left hand, Green - left leg, Black - right leg.

The chest electrodes are numbered, also have a color and are equipped with rubber suction cups. They are installed in a strictly defined place on the chest. Let us present the method of installing electrodes in the chest leads in the form of a diagram.

Location on the chest:

• V1 (red) 4th intercostal space 2 cm from the edge of the sternum on the right,
• V2 (yellow) symmetrically from v1 (2 cm from the edge of the sternum on the left),
• V3 (green) to the average distance between v2 and v4,
• V4 (brown) 5th intercostal space along the midclavicular line,
• V5 (black) to the middle distance between v5 and v6,
• V6 (blue) at the same horizontal level as v4 in the midaxillary line.

For better contact with the electrodes, it is advisable to degrease the skin with alcohol; it is recommended to shave the thick hair on the chest and moisten the skin with water or a special electrode gel (OKPD code 24.42.23.170). For better contact of the electrodes with the skin, you can place a damp cloth under the electrode plates. After completing the recording of the cardiogram, the electrodes are removed from the patient’s body, the remaining gel is removed with a napkin, processed, disinfected, dried and placed in a special container. Such manipulations are carried out with reusable electrodes. They can be reused to record a cardiogram for another patient.

4 Alone? A lot of?

ECG electrodes are either reusable or disposable. Reusability is not the only classification of electrodes for recording ECG. But there is no need to go deeper into the classification. Most often, in the functional diagnostic rooms of clinics, you can still see reusable electrodes on the ECG machine: limb, chest, with a screw and clamp, a set of six bulbs. Reusable electrodes are economical and therefore retain their position in medicine.

Disposable electrodes have appeared relatively recently; their advantages include high accuracy of the transmitted signal, good fixation and stability during movements, and ease of use. Disposable electrodes are widely used in intensive care units, Holter monitoring, pediatrics, and surgery. The disadvantages of disposable electrodes include the impossibility of reuse.

There is also an ECG with a vacuum electrode application system, which is ideal for performing functional stress ECG tests. The electrodes in the system with vacuum application fit very tightly and are well fixed, this allows you to easily take a cardiogram when the patient moves without losing the quality of the ECG signal. And if the electrode suddenly disconnects, the system will let you know about it, since an ECG with a vacuum electrode application system is able to “control” the detachment of the electrodes.

5 Recording a cardiogram

After applying the electrodes and connecting them to the device, the leads are fixed and recorded on the paper recording tape of the cardiograph. In the case of an ECG, the patient’s arms and legs will be “conductors” of the electrical activity of the heart, and an imaginary, conditional line between the arms and legs will be leads. Thus, 3 standard leads are distinguished: I forms the left and right arms, II forms the left leg and right arm, III forms the left leg and left arm.

First, using limb electrodes, an ECG is recorded in standard leads, then in amplified ones (aVR, aVL, aVF) from the limbs, and then in chest leads (V1-V6) using chest electrodes. The electrocardiograph has a scale and a lead switch, and there are also buttons for voltage and tape feed speed (25 and 50 mm/s).

Recording devices use a special registration tape (for example, OKPD code 21.12.14.190), in appearance it resembles graph paper, has divisions, where each small cell is 1 mm, and one large cell is 5 mm. At a speed of movement of such a tape of 50 mm/sec, one small cell is equal to 0.02 seconds, and one large cell is equal to 0.1 seconds. If the patient is recording an ECG at rest, he should be explained that at the time of direct recording one cannot talk, strain, or move so that the recording results are not distorted.

6 Common mistakes when recording ECG

Unfortunately, when recording a cardiogram, errors are common both on the part of preparing patients for the procedure and on the part of medical workers when carrying out the ECG registration algorithm. The most common errors leading to distortion of ECG results and the formation of artifacts are:

• Incorrect application of electrodes: incorrect placement, rearrangement of electrodes, incorrect connection of wires to the device can distort the ECG results;
• Insufficient contact of electrodes with the skin;
• Patient neglect of preparation rules. Smoking, overeating, drinking strong coffee before the procedure, or excessive physical activity when taking a resting ECG may give incorrect data about the electrical activity of the heart;
• Trembling in the body, uncomfortable positioning of the patient, tension of individual muscle groups in the body can also distort the data when recording an ECG.

In order for the ECG results to be reliable and truthful, healthcare workers need to clearly understand the algorithm of actions when taking a cardiogram and the technique for conducting it, and patients must approach the study responsibly and follow all the rules and recommendations before conducting it. It should be noted that ECG has no contraindications or side effects, which makes this research method even more attractive.

Homemade cardiograph (several options)
The homemade ECG

??????

A small toy based on a USB oscilloscope.
or a cheap USB-sound board for SKYPE telephony.

Allows you to write a cardiogram to a .bin file
and also reproduce the results of saved measurements in real time.
Unfortunately, I did not find programs for decoding cardiograms
and I don’t know how to save the file correctly, so it’s just a *.bin file.
May be useful for detecting rare ECG abnormalities,
which can be difficult to record when rare
and short visits to the ECG room
or just to monitor your heart if you know a cardiologist (.

View the list of references on this topic and add your information
it is possible on the forum in the topic What books do you recommend?

Find out what to do with the received cardiogram
and you can suggest your option on the forum
on topic Cardiogram received. What's next?

There on the forum you can look and add your own Links to sites about cardiology and cardiographs

We will connect the electrodes according to the simplest scheme:

You can start by simplifying the task by connecting the lead wires to the shoulders and the ground wire to the wrist.
Possible connection options:

To begin with, the electrodes can be homemade, but given the complexity of the task, it is advisable over time to acquire industrial ones made from special materials.
Here, for example, is one of many options:
Disposable ECG Electrode is Ag or AgCl electrode, which consists of base lining material, conductive gel, and electrode buckle.

Since the amplifiers do not have galvanic isolation, all experiments for safety reasons and to reduce interference must be carried out with a laptop not connected to a 220V network.

1. Cardiograph on base USB oscilloscope

Program ECG.llb For version LabVIEW5.0

Amplifier module - any amplifier with a closed (>4 µF) input and Kus >=100

In my case, I use the KARDIO module from a USB oscilloscope.

The diagram and design look like this:

DA1 can not be installed, and the R RL wire can be connected to ground.

R6+R7+R8 = 100-400 Ohm (150)

Connect the left and right hand inputs to R11 and R12 through non-polar capacitors 8.0 -10.0 µF to eliminate possible galvanic offset (up to hundreds of µV)

Cardiac amplifier board file in JPG format: CARDIO_JPG.zip in PCB2004 format: Kardio_PCB2004.zip

The microcontroller module board and firmware are on the oscilloscope module page.

Everything is combined into one housing for compactness. If this is not necessary, you can simply use the oscilloscope module
paired with a cardiac amplifier module. Or make your own device that transmits data in the format specified in the oscilloscope module.

Corrector program. Korrektor.llb

Allows you to align the cardiogram:

This option might look like this:

2. Cardiograph based on USB sound card
ECG of the USB sound card

Version for USB sund card based on a chip for SKYPE phones AP-T6911 or any other that allows you to measure DC voltage:

1 . We buy something like this for $2-10: for example this one: http://www.dealextreme.com/details.dx/sku.22475
2 . Turn off the microphone amplifier. All that remains is a 10-bit ADC with an input offset of about 2.5 volts
which will have to be compensated if you measure constant voltage.
Upgrading the USB - Sound board (See pictures)

It looks something like this:

Provided that there is a SKYPE phone chip AP-TP6911_02EV10

Warning: models change constantly.....

Unfortunately, the USB and SOUND options create *.bin files with different signal sampling rates.
If in ECG_USB_SND.llb this can be corrected in the program, then the EXE version is hardcoded at 48000/32 samples per second.
If you are working with a standard sound card, you will have to find adapter capacitors in the microphone input channel
(usually 1 at the input and 1 in the microphone amplifier) ​​and increase their capacitance to tens of microfarads.

3. Cardiograph based on bluetooth headset with microcircuit BC31A223A (From Sony Ericsson phones):

1. Preparing the headset.
It consists of disconnecting the microphone by removing the capacitor C10 and connecting it to the differential input connector
microcircuit microphone amplifier (MIC_N and MIC_P) and voltage VOUT (2.7V) to power amplifiers connected to the connector.
How this was done is shown in the figure below.
I decided not to touch the headset phone for now in order to use it for its intended purpose.

2. Installing BLUETOOTH drivers with headset support.
In my case, the following drivers did not work:

Microsoft - it does not support the headset profile

Widcomm- it didn't recognize both of my USB-Bluetooth devices

Stopped at Bluesoleil - Installed the version BlueSoleil 6.4.314.3

The issue is quite problematic, so someone may have to solve it differently.

After this, you can start experimenting.

Currently the following results are available:

The maximum input signal has a swing of +/- 32 mV with 15 bits of resolution and a sampling frequency of 8 kHz, which allows you to take a cardiogram
when connecting electrodes through an isolation capacitor to the MIC_N and MIC_P contacts connected to an external connector.
An example of pictures is shown in the figure.

The connection turned out to be quite poor quality. Quite often there are interferences or interruptions in the flow, which manifests itself in the form of pulsed noise.
So Holter ECG monitoring via Bluetooth headset seems to be impossible.

After the usual procedure for connecting the headset, the cardiogram can be recorded in a convenient way for you in a *.wav file
for further processing or use the above program Cardiograph based on USB sound board

4. Cardiograph on base

In this project we will create a portable electrocardiograph and heart rate monitor. Of course, the device can be used for medical purposes.

PLEASE NOTE: To reduce the risk of electric shock, use battery power only. The electrodes are isolated from the main circuit by an instrumentation amplifier, but still use extreme caution. The manufacturer of the device is not responsible for possible accidents.


The device circuit is very simple; it can be placed on a single-sided board.

Step 1: Component List

- (1) INA128 instrumentation amplifier
- (1) 741 series operational amplifier
- (1) Arduino Uno microcontroller
- (1) 16x2 LCD display
- (1) Stabilizer 7805
- (1) 8 ohm mini speaker
- (1) Ultra bright LED (Project uses 10mm LED)
- (1) Diode 1N3064
- (2) 9V battery with connectors
- Bread board
- Wire jumpers

Resistors:
- (2) 100 Ohm, 1/4 W
- (1) 470 Ohm, 1/4 W
- (1) 1 kOhm, 1/4 W
- (2) 10 kOhm, 1/4 W
- (2) 100 kOhm, 1/4 W
- (1) 1 MΩ, 1/4 W

Capacitors:
- (1) 10 nF
- (1) 47 nF

For electrodes:
- One meter of wire
- Antistatic bracelet
- Medical patch
- Foil
- (2) scrapers
- Shower gel (as a replacement for gel for taking electrocardiograms)

Optional component:
-Oscilloscope for displaying ECG.

Step 2: Create a Schema

Below is a schematic diagram of this project. The two electrodes are connected to inputs 2 and 3 of the INA128 instrumentation amplifier. An additional reference electrode (antistatic wrist strap, placed on your right leg) is connected to ground. This will allow you to use unshielded cable in your project.

The best signal is taken after the low-pass filter (between two 100 kOhm resistors). I intend to connect the oscilloscope probe at this point to demonstrate the picture, although the oscilloscope can also be used to check other control points.

Step 4: Making Electrodes


Securely attach two scrapers to the ends of the pair of exposed conductors. Cut pieces of foil to the required size and attach to scrapers. You should get it as shown in the photo. You can experiment with the design to get the best results.
When ready, apply some gel to the electrodes and use medical tape to securely attach to the chest.

Step 5: Place the electrodes and check the functionality of the device!

Place an antistatic wrist strap on your right leg and connect it to ground.

Place the electrodes on your chest and position them to get the best signal. This will take some time due to fluctuations in the electrical connection.

Below is a video of the electrocardiograph in action:
https://www.youtube.com/watch?v=85wpkerNxlk

As an experiment, you can place electrodes in different places on the body to get a different signal. Professional electrocardiographers use 10 electrodes to create a signal map. The photo shows the approximate location of the electrodes. This configuration works flawlessly since I chose ventricular bursts to measure frequency.

You may also see noise signals caused by muscle movement as the electrodes pick up such signals. If you want to get rid of such signals, then don't move!