Electrocardiography 2 (2. LF UK)

Task assignment

 * 1) Record a 12-lead ECG of one task force member.
 * 2) Measure and evaluate the measured signal according to the instructions, sketch the electrical axis of the heart.

Theoretical introduction


Electrocardiography (ECG) is the basic method of measuring the electrical activity of the heart muscle (myocardium). This method is completely non-invasive. It enables the detection of most serious heart diseases (arrhythmia, acute or previous damage of the heart muscle...). Its principle is the recording of electrical heart activity and in the form of an Electrocardiogram (time recording of ECG waves) enables its evaluation.

The signal, that was created in the SA node is transmitted Through the cardiac conduction system until it spreads throughout the myocardium, which consists of cardiomyocytes. An action potential is generated on the extracellular membrane of each cardiomyocyte during its activity. When the ion channels open, the membrane is depolarized, which leads to contraction of the muscle fiber and thus to systole. Atrial systole precedes ventricular systole. After the end of systole, diastole occurs, during which the action of ion pumps repolarizes the membranes, i.e. creates a resting membrane potential.

During the ECG, however, it is not possible to record the action potentials of individual heart cells, but only the overall electrical manifestation of all these cells over time, the so-called summation potential of the entire myocardium.

The principle of measuring
As already mentioned, different potentials are created in the heart during its activity, which have a specific direction and size, therefore they can be expressed as vectors. Each vector is typical in direction and size for a certain phase of cardiac activity, viz. image Propagation of depolarization. The first successful method of measuring was created by the Dutch physiologist Willem Einthoven, who was later awarded the Nobel Prize for his discovery. The method consists of placing three bipolar leads on the righthand, on the left hand and on the left ankle. Between these three leads is fomed an imaginary triangle, in the center of which is the human heart, it was called Einthoven's after its discoverer, which can be seen in the attached picture. During cardiac activity, a measurable potential enters between individual leads, the size and direction of which can be expressed by vector. This way we get three vectors between individual leads. These vectors are then added so that the resulting vector starts in the center of the triangle, i.e. in the heart. The resulting vector shows us both the site of the cardiac potential and the direction of its propagation. We can get an ECG graph by plotting the measured value as a function of time.

If the result is to be as accurate as possible, it is necessary for the patient to be at rest and not to move, because activity of any muscle creates a potential, that would invalidate the measured results, and the electrical conductivity of the tissues can also be changed with movement.

Course of one cardiac cycle
The initial signal of the SA node is so weak that it is practically not recorded during a normal ECG recording. Therefore, we see the following graphoelements on a typical ECG recording (in II. Einthoven lead):
 * P wave corresponds to atrial depolarization (resulting in atrial systole). (The atrial repolarization is not visible on the ECG recording because it has low amplitude and it is overlaid by the stronger QRS complex that occurs at the same time.)
 * PQ segment (or 'PR segment) corresponds to delay of excitation in the AV node; we measure it from the "end" of the P wave to the beginning of the ventricular complex.
 * PQ interval is the time from the beginning of the P wave to the beginning of the ventricular complex - thus it includes the width of the P wave and the PQ segment. (Since the following Q oscillation may not always be visible, it is sometimes referred to as the 'PR interval - ie from the beginning of the P wave to the beginning of the R oscillation.)
 * QRS complex represents depolarization of the ventricles (and, as a result, ventricular systole). It typically consists of three "oscillations":
 * Q – is the first negative oscillation, may not be present
 * R - is any positive oscillation Normally only one occurs. If there are more R oscillations in the complex, they are marked with an asterisk (eg R*)
 * S – is every negative oscillation after at least one R. If there are more, they are marked similarly to R.
 * 'ST segment - is the part between the end of the QRS complex (the so-called "J point" or "junction") and the beginning of the T wave
 * T wave represents repolarization of the ventricular myocardium on the ECG recording. It is terminated during the T wave.
 * QT interval is the time between the beginning of the QRS complex and the end of the T wave.
 * U wave is rarely visible. Its origin is unclear.

Duration of cardiac cycle
Duration od cardiac cycle is most easily determined from the R-R interval, which is the interval between the R oscillations of two consecutive cardiac systole. From it we will then calculate the instantaneous heart rate in "bpm" (beats per minute) or min-1:

$$f [\textrm{min}^{-1}] = \frac{60}{\textrm{R-R interval [s]}} = \frac{60000}{\textrm{R-R interval [ms]}}$$

Limb electrodes

 * R (right hand)
 * L (left hand)
 * F (left leg)
 * N (right leg)

Precordial electrodes
Six electrodes V1 to V6 placed directly on the chest of the patient:
 * V1 in the fourth intercostal space to the right of the sternum
 * V2 in the fourth intercostal space to the left of the sternum
 * V3 between electrodes V2 and V4
 * V4 in the fifth intercostal space in a line running through the centre of the left clavicle
 * V5 in the fifth intercostal space in a line running through the anterior lash of the axillary fossa
 * V6 in the fifth intercostal space in a line below the centre of the axillary fossa.

Electrodes
The specific wiring of the ECG electrodes creates the so-called ECG leads. These leads are then divided into: Thus, we must consistently distinguish between the terms:
 * by the electrodes from which they are formed:
 * limb'
 * thoracic'
 * by the method of connection:
 * bipolar' (potential difference between two electrodes)
 * unipolar' (potential difference between an electrode and a reference point artificially created by means of suitably wired resistors)
 * electrode' - a metallic component, placed on the body of the person being examined; its potential is transmitted via a cable to the ECG device, and thus the potential of this lead and the electrode is identical (ignoring possible interference)
 * lead' - is created in the instrument itself by the way in which the inputs of its differential amplifiers are connected to the individual electrodes or reference points

Einthoven's leads
Bipolar connection - the measured signal corresponds to the potential difference between two electrodes. The electrode placed on the "left hand" is marked with the letter L (left) - the measured potential is marked ΦL, on the "right hand" with the letter R (right) - the potential Φ R and on the left ankle F (foot) - potential ΦF.

Einthoven's limb leads are denoted by the Roman numerals I, II and III. The following relations apply for the calculation of the stresses of the end leads: $$ \begin{align} U_{I} &= \Phi_{L} - \Phi_{R}\\ U_{II} &= \Phi_{F} - \Phi_{R}\\ U_{III} &= \Phi_{F} - \Phi_{L} \end{align} $$

The N (neutral) electrode, which connects to the right leg', is not included' in the actual sensing and serves only as a ground.

Wilson limb terminals (unipolar)
3 Wilson supplemented Einthoven's bipolar leads I, II, III with 3 unipolar leads by using three resistors to create a reference point (Wilson's clamp) against which he then related the potential waveforms of the limb electrodes R,L,F to create Wilson's limb leads VR, VL, VF.

Calculation of the Wilson clamp potential: $$ \begin{align} U_{W} &= \frac{\Phi_{R} + \Phi_{L} + \Phi_{F}}{3} \end{align} $$

Goldberger leads (unipolar)
Instead of Wilson's central clamp, Goldberger used a custom reference point for each of the R, L, F electrodes, created by a voltage divider from the remaining two limb electrodes, thus increasing the amplitude of the unipolar limb leads by 50%. The resulting unipolar limb leads are called augmented (i.e., extended) and are thus denoted aVR, aVL, and aVF.

For the calculation of the Goldberg leakage voltage the following relations apply:

$$ \begin{align} U_{aVR} &= \Phi_{R} - \frac{\Phi_{L} + \Phi_{F}}{2}\\ U_{aVL} &= \Phi_{L} - \frac{\Phi_{R} + \Phi_{F}}{2}\\ U_{aVF} &= \Phi_{F} - \frac{\Phi_{R} + \Phi_{L}}{2} \end{align} $$

Wilson thoracic leads (unipolar)
The voltage of the chest leads is calculated as the potential difference between the given chest electrode and the central Wilson clamp.

Chest lead voltage calculations:

$$ \begin{align} U_{V1} &= \Phi_{V1} - \Phi_{W}\\ U_{V2} &= \Phi_{V2} - \Phi_{W}\\ U_{V3} &= \Phi_{V3} - \Phi_{W}\\ U_{V4} &= \Phi_{V4} - \Phi_{W}\\ U_{V5} &= \Phi_{V5} - \Phi_{W}\\ U_{V6} &= \Phi_{V6} - \Phi_{W} \end{align} $$

Standard 12-lead ECG
Combining Einthoven's bipolar leads I, II, and III, Goldberg's unipolar leads aVR, aVL, and aVF, and the six thoracic leads, we obtain a standard twelve-lead ECG.

Electrocardiograph design
supplement:

BTL-08 WIN
BTL-08 WIN is the original company software designed to communicate with the BTL-08 S ECG electrocardiograph. Due to the fact that it is the software for the BTL-08 S ECG unit we have in our practices, which is no longer in production (it has been replaced by a newer version), the manufacturer has made the BTL-08 WIN software available as a free download on their support site. If this program detects that there is no ECG unit connected to the computer, it automatically starts DEMO, i.e. it behaves in the same way as if it were receiving an ECG signal from a connected patient. This will allow us to download this program and learn how to use it at home.

Installing and setting up Ecg

 * 1) Find the manufacturer's website BTL Zdravotnická technika, a.s.
 * 2) Select Service / Software in the top bar
 * 3) Find Cardio: ECG and ergometry software: BTL 08 ver. 6.12.zip
 * 4) Download the installation file: BTL_08_6.12.zip (size 15 MB)
 * 5) Unzip the installation file (creates a directory BTL 08 ver.6.12)
 * 6) In this folder is the installer Setup_BTL08win-6.12.exe, which we run
 * 7) The BTL-08 WIN program is installed by default in the C:\BTL08Win folder (it takes only 10 MB on the disk)
 * 8) In this folder is the program Ecg.exe, which we run
 * 9) After the first run we get the message: data file not found! I can't find the data file. What to do? (Cannot find 08data.mdb.)
 * 10) Select the option: ? Use demonstration F10'
 * 11) In the Settings menu we can set Language selection

Controlling Ecg
We will get familiar with the operation of the program for ECG capture, storage, display and processing and learn how to use it. The program can be controlled either with the mouse or with the function keys.

Patient data stored

 * 1) In the menu on the top right, click on the menu F3 File Cabinet.
 * 2) In the Ambulance file we can find the charts of patients Dowe John and McBeal Ally, in the Clinic file we can find the chart of patient Novotný Rudolf
 * 3) Clicking on a patient's name allows us to edit the patient's tab: Patient Properties F2
 * 4) When we double-click on a patient's name, we have the option to make a new ECG recording (a shot) or view a saved recording (e.g. Dowe John has 4 ECG recordings saved).
 * 5) Double click on a record to see ECG waveforms from twelve ECG leads: left limb, right chest. We can change this arrangement.
 * 6) We can move around in the recording by dragging the bottom bar or by using the arrow keys or PageUp and PageDown
 * 7) Try changing the paper feed speed F4, amplitude F5 or filters F6
 * 8) Comparison F7' allows us to compare two different records
 * 9) Averaging F8' will average several cardiac revolutions. To average the curve, we have to drag the red squares to specify the time points that the program tried to set automatically:
 * 10) p_on' start of wave P
 * 11) p_off' end of wave P
 * 12) qrs_on start of QRS compex
 * 13) qrs_off' end of QRS complex
 * 14) t_off end of T wave
 * 15) The Confirm Diagnosis F5 option saves the time points as we have specified them
 * 16) Top left we see the different intervals and amplitudes for the displayed lead
 * 17) Option Details F4 shows a detailed table of amplitudes for all leads and the slope of the calculated electrical axes of the P wave, QRS complex and T wave

ExaminationOutput
This action saves the result of the examination in two files: the first shows the ECG curves and the second shows their description.
 * 1) Print F2'
 * 2) Preview F2'
 * 3) Save Image'
 * 4) Save as PNG'

DEMO
Now that we have learned how to work with the saved recordings, let's try making a new recording:
 * 1) On the Records page, next to surgery and outpatient, we will create another workplace whose folder we will name with the name of our circle, e.g. Circle 1
 * 2) Where we create and fill in a new patient card.
 * 3) Now we have the opportunity to record:
 * 4) New standard ECG (i.e. a 12-lead ECG with the possibility of taking several 10-second shots)
 * 5) New long recording (i.e. a recording of up to several minutes, but with only one or two selected leads).

StandardECG
When this option is selected, a warning appears in the window within a certain time that no connected unit has been found and that DEMO is being started. The recorded waveforms then appear, with a large grey DEMO watermark on a black background.

During recording, we can again try changing the settings for paper feed speed F4, amplitude F5 or filters F6.

After pressing the Enter key or clicking on the red heart at the bottom right, a ten-second ECG recording is saved. This can be done several times. (In subsequent viewing, these snapshots will be separated by vertical white lines.)

To end the recording, press the Esc key or click on End Recording.

LongECG
With this option, we must first set: After that, the recording will proceed similarly to the first one. We must not be mistaken that, as before, we will monitor all 12 ECG leads - only the one selected by us will be saved afterwards. When we are ready to start recording (when the recording is artifact-free), press Enter or click on the red heart outline on the bottom right. The whole outline will turn red, indicating that recording is in progress. After half a minute, the heart shows how much time is left. During this time, we don't click on anything else, the recording ends and saves itself after the specified time.
 * 1) Which lead or which two leads we want to store (just select one lead, the one that had the clearest R-waves in the standard ECG).
 * 2) The sequential length of the recording (1.5 min, i.e. 90 s is enough).

Display and evaluation
We can now view and evaluate both records in the same way we learned on the saved patient data.

Check Questions
. 'As part of your homework, you will check your understanding by taking the Moodle Entry Test''. The pass mark is 75% to be admitted to the practical.''' In case of failure, the test can be repeated.
 * 1) What is the principle of the ECG?
 * 2) What are myocytes?
 * 3) What is the function of myocytes?
 * 4) What are the manifestations of myocytes?
 * 5) What is the action potential of a myocyte?
 * 6) What is the summation potential?
 * 7) Do we record action potential or summation potential during an ECG?
 * 8) What can the abbreviation ECG stand for?
 * 9) What is an electrocardiogram?
 * 10) What is an isoelectric line?
 * 11) Draw a typical ECG curve including a description and the corresponding axes!
 * 12) Label the amplitude of the QRS complex on the ECG curve!
 * 13) How do we interpret the different graphic elements of the ECG recording?
 * 14) How does atrial depolarization appear in the ECG recording?
 * 15) How does atrial repolarization appear in the ECG recording?
 * 16) How does ventricular depolarization appear in the ECG recording?
 * 17) How does ventricular repolarization appear in the ECG recording?
 * 18) What is a QRS complex?
 * 19) What is the interval in the ECG recording?
 * 20) What is a segment in an ECG recording?
 * 21) In what units do we measure the amplitude of an ECG recording?
 * 22) What is the approximate amplitude of an ECG recording?
 * 23) In what units do we measure heart rate?
 * 24) What is the approximate value of normal heart rate?
 * 25) What is the R-R interval?
 * 26) What can we use the R-R interval for?
 * 27) What types of electrodes do we use?
 * 28) How do we fix the electrodes?
 * 29) How do we treat the skin before fixing the electrodes?
 * 30) Where do we place the limb electrodes?
 * 31) Where do we place the chest electrodes?
 * 32) What is the standard colour coding of the electrodes?
 * 33) What is a lead?
 * 34) What is the difference between electrodes and leads?
 * 35) What are the different types of leads?
 * 36) What are bipolar leads?
 * 37) What are unipolar leads?
 * 38) What are Einthoven leads?
 * 39) What do we call Einthoven leads?
 * 40) What are Goldberger leads?
 * 41) What are Wilson's leads?
 * 42) What are limb clamps?
 * 43) What are thoracic clamps?
 * 44) What is a Wilson clamp?
 * 45) How does a differential amplifier work?
 * 46) What are filters?
 * 47) What is a time constant?
 * 48) What is the physical unit of recording speed?
 * 49) What are the usual recording speeds?
 * 50) Draw and describe Einthoven's triangle!
 * 51) Draw and describe the individual Einthoven leads in Einthoven's triangle!
 * 52) Draw the vectors representing the Goldberger vertices in the Einthoven triangle.
 * 53) How do we label the Goldberger vertices?
 * 54) What is the electrical heart vector?
 * 55) What are the electric heart axes?
 * 56) What is the main electrical heart axis?
 * 57) How do we graphically construct the main electric heart axis vector?
 * 58) How do we measure the slope of the electrical heart axis?
 * 59) What are the approximate physiological values of the inclination of the main electrical cardiac axis?
 * 60) How do we calculate the heart rate from the R-R interval?
 * 61) What is heart rate variability?
 * 62) What does the abbreviation HRV stand for?

Real patient ECG examination procedure
Measure and record the 12-lead ECG of one member of the working group.
 * 1) Before starting the actual ECG recording, fill in the patient's information on the first page of the protocol: age, height, weight, BMI, family history and personal history. In particular, record in the medical history factors that could influence the occurrence of cardiovascular disease, such as smoking, obesity, psychological problems, alcoholism, etc.
 * 2) On the connected computer, start the BTL-08 Win program and open the Folders item where, in the folder corresponding to the circle number, open the New Patient card and fill in the required information about the person being examined.
 * 3) Check and untangle the cables, if necessary, and attach the appropriate electrodes to their bananas.
 * 4) Patient lies down on the bed with limbs extended
 * 5) Wet the skin at the electrode sites to reduce skin resistance.
 * 6) Placement of clamp electrodes (limb leads):
 * 7) *N' - black - right lower limb
 * 8) *'R' - red - right upper limb
 * 9) *'L' - yellow - left upper limb
 * 10) *'F' - green - left lower limb
 * 11) Placement of suction electrodes (chest leads): It is not necessary to connect the chest leads to complete the task.
 * 12) *V1' - in the 4th intercostal space just to the right of the sternum
 * 13) *'V2' - in the 4th intercostal space just to the left of the sternum
 * 14) *'V3 - midway between V2 and V4
 * 15) *'V4' - in the 5th intercostal space in the medioclavicular line on the left
 * 16) *'V5 - between V4 and V6
 * 17) *'V6 - at the same level as V4 in the medial axillary line on the left
 * 18) After the electrodes have been correctly positioned, turn the ECG unit (on/off)' on and start the program with the new standard ECG examination. If the unit is not switched on, External Unit is NOT connected will appear. In the case of an unconnected unit, the alert will disappear by itself and the DEMO version will appear - this is not an investigation of a real patient.
 * 19) Check the alert parameters, which should correspond to the following values, change them if necessary:
 * 20) *Time base:' 25 mm/s
 * 21) *'Amplitude:' 10 mm/mV
 * 22) *'Filter: 50 Hz
 * 23) *Time constant: 3.2 s
 * 24) Save three 10-second bursts of clean recording with the Enter key, each more than 10 seconds apart.
 * 25) End the recording with the Esc key, check and review the saved takes.
 * 26) Turn off the ECG unit (long press on/off)
 * 27) Disconnect the patient.

Evaluation of ECG
For a more detailed article on ECG scoring, see ECG description
 * 1) You have already learned to work with the program in your home training, so now just briefly:
 * 2) Close the file with the saved ECG recording.
 * 3) Choose the best shot with the fewest artifacts (the shots are separated by vertical white lines).
 * 4) Analyse the ECG from the averaged signal (click on the right menu).
 * 5) We should see one cardiac revolution (at the beginning with a P wave and at the end with a T wave). If not, we select another section to average.
 * 6) The program will display the averaged second lead. If the waves here are not very distinct, we can use another limb lead. (The lead designation is displayed on the upper left. Use the up and down arrows to move between the leads.)
 * 7) The program will automatically try to find the beginning and end of the QRS complex, the P wave and the end of the T wave.
 * 8) Automatically positioned points (markers) are specified by shifting (grasping points on the curve with the mouse).
 * 9) You can then verify the position of the markers in other leads and then return to the originally selected lead.
 * 10) Click Confirm diagnosis. (The markers change colour and can no longer be moved.)
 * 11) Click Details to see an automatically calculated table of intervals and amplitudes.
 * 12) Check if the automatically calculated table matches the record.
 * 13) You will measure the values that the program did not evaluate or evaluated incorrectly using the yellow cursors (after invalidating the diagnosis).
 * 14) Write the correct values in the log.
 * 15) Finally, click again to confirm the diagnosis and leave the window with the averaged signal.
 * 16) Check the length of the R-R interval in the selected sample.
 * 17) Print a sample of the five-second acquisition into a PDF file (Use the arrow keys to move around the acquisition and print the five-second preview uninterrupted by the thick vertical white line with the Enter button). Usual print parameters:
 * 18) *Grid:' normal
 * 19) *'Offset: 25 mm/s
 * 20) *'Amplitude: 10 mm/mV
 * 21) *'Printed record length: 5 s
 * 22) After this pick-up you will still check the values you have entered in the log (intervals, segments, amplitudes, etc.)
 * 23) You will then save the file with the ECG curves followed by the table of automatically calculated values as an attachment to the protocol in moodle and put its name on the cover page of the protocol.
 * 24) The discrepancy between the automatically calculated values and your findings will then be discussed.

Heart Rate Variability
. Investigate the heart rate variability of the subject.

Heart rate variability (HRV) tells us the difference in spacing between heartbeats. If a patient has a heart rate of 75 beats per minute, there will not always be the same spacing between heartbeats. Each time the interval will be slightly different. At a lower heart rate there is more room for variation, but at a higher heart rate (e.g. 180 bpm) the room is very narrow. This means that a person with regular exercise, and therefore better overall fitness, will have a higher HRV because at a similar workload they will have a lower heart rate relative to a person who does not exercise regularly.

HRV is therefore a physiological adaptation of heart rate, which is one of the typical features of autonomic integration functions of living organisms. High heart rate variability is a sign of good system adaptability, i.e. "healthy" regulation of cardiac functions and consequently "healthy" organism. Conversely, reduced variability is usually a sign of a violation of system adaptability and should lead to a more detailed, targeted diagnosis of its cause. Nowadays, HRV is mainly used in cardiology, diabetes and as a diagnostic method for many serious clinical conditions. From renal failure, to post-stroke conditions, to pre- and post-operative monitoring and estimation of the risk of potential complications. But it can also be a method that tells us how fit our body is overall.

One of the pitfalls of this method is that HRV is influenced by a large number of factors, both external and internal. This is why with this method we do not use comparisons of results between patients (whether of the same sex, age, fitness), instead we use comparisons of HRV results at different time intervals for each patient separately.

Evaluation
Heart rate variability (HRV) expresses the balance of the autonomic nervous system, or the ratio of sympathetic to parasympathetic activity; in other words, we define the influence of the autonomic nervous system on each organ system. Exhalations and inhalations affect our heart rate, so we will check this in this problem with a long ECG recording that takes 3 minutes. From the recording of this take, we can then calculate the difference in heart rate, or changes in the length of the R-R interval. 'Workflow (controlled respiration rate method) ''If the subject becomes nauseous (lightheaded, dizzy, etc.) during the examination, immediately stop the examination and notify the assistant present. This examination cannot be carried out on persons who are prone to epilepsy, so the medical history must also be directed in this direction.''
 * 1) Proceed similarly to the ECG measurement in task 1 (points 1-5), then in the New Standard ECG acquisition mode select the lead with the most significant R waves and end the acquisition with the Esc key.
 * 2) Start New Long ECG acquisition and set the recording duration to 1.5 minutes.
 * 3) Prepare the stopwatch and instruct the subject to take a breath on command while pressing the Enter key to start the long take. After 5 seconds, instruct the subject to begin exhaling. After another 5 seconds, instruct the subject to inhale again. This will be done for 5 seconds in the inhalation phase and 5 seconds in the exhalation phase. After the measurement period, a red heart will appear at the bottom right, showing the time to the end of the examination after half a minute. After the time has elapsed, the long acquisition will terminate itself (do not press any key). (Exceptionally, the program does not terminate the acquisition and the time continues into negative values. In this case, the record is not saved and the HRV test must be repeated.)
 * 4) Turn off the ECG unit with the on/off button and disconnect the examinee from the electrodes.
 * 5) Save the print parameters.

Evaluation of the record:'

Calculation' Factors influencing the examination:
 * Process one minute of footage.
 * From the R-R intervals, calculate the average heart rate.
 * Identify the 5-second intervals in the recording corresponding to the inspiratory and expiratory phases.
 * Calculate the average length of the R-R intervals and the heart rate during these periods.
 * Evaluate and describe the variability of heart rate as a function of the phases of the respiratory cycle.

ACE-inhibitors, calcium channel blockers, α- and β-blockers, digitalis, nitrates and nitroglycerin, diuretics, antiarrhythmics, bronchodilators, sympathomimetics, peripheral vasodilators, antihyperlipidemics, tricyclic antidepressants, anticholinergics, MAO inhibitors, high-dose L-dopa, nicotine, alcohol

What should be observed before measurement?
 * Exercise before measurement
 * Keep your eyes open during the measurement
 * Do not smoke, drink coffee or other caffeinated beverages at least 3 hours before the measurement
 * Drink alcohol at least 1 day before the measurement
 * Do not take measurements immediately after a meal

Image attachment

 * '/Evaluation' - screenshots of the ECG period evaluation

Videotutorial of the Department of Biophysics
https://www.youtube.com/watch?v=QogpdabhkzI
 * /Screenwriter

Link to QogpdabhkzI video

StudentVideotutorial
https://www.youtube.com/watch?v=jE8XS5RI7XA

Link to video jE8XS5RI7XA

Note: The video was filmed while still in the old makeshift building. At the time of its development by the students, we were still printing out the curves on paper and filling out pre-printed paper logs. Nowadays we don't print anything on paper anymore, but we go in paper-less mode: Instead of printing to a printer, we print images to files and put these into an electronic report in spreadsheet format, which we fill out and save to moodle.

Related articles

 * Portal: Biophysical practics (2. LF UK)
 * Heart
 * Electroencefalography
 * Heart rhythm disorders
 * ECG description

Literature
23. 8. 2015 [cit. 2015-11-26]. Available from: http://www.szsmb.cz/admin/upload/sekce_materialy/EKG_a_EEG.pdf
 * Literatuti běžnému stavura. EKG. [online].
 * EKGKvalitně. http://ekg.kvalitne.cz . [online]. [cit. 2015-11-26]. Available from: http://ekg.kvalitne.cz/svody.htm
 * EKG. EKG. [online]. 7.4.2009 [cit. 2015-11-26]. Available from: http://www.szsmb.cz/admin/upload/sekce_materialy/EKG_a_EEG.pdf¨