Electrocardiography is a method of studying the work of the heart muscle. Using the ECG apparatus, the generated electric fields are recorded and the results are further displayed in the form of a graphic image on thermal paper (in most cases). The first ECG device recorded data on photographic film, then ink recorders existed. If the device is completely electronic, then the data can be stored in the computer's memory.
Using Electrocardiographs
The electrocardiography procedure is carried out with the following objectives:
- determination of the frequency and regularity of contractions of the heart muscle;
- if you need to determine the presence of coronary disease or heart attack;
- if it is necessary to confirm or deny the presence of electrolyte deficiency;
- clarification of the presence of heart block;
- assessment of the state of the dynamics when conducting samples with a load;
- if you need to clarify the anatomical and physiological characteristics of the heart (for example, left ventricular hypertrophy) ;
- if you need to confirm or deny the development of pulmonary embolism;
- for preventive purposes during the medical examination of the population.
Modern devices
Even 20-30 years ago, the ECG apparatus was an immense machine, which was difficult to transport and took up a lot of space in the room. Modern technologies have made it possible to reduce the dimensions of devices (up to portable ones) without losing quality in functionality.
An ECG device can record one or several channels simultaneously, on which division into groups is based. In addition, it must be equipped with certain software:
- syndromic conclusion on the results of the data;
- in case of cardiac arrhythmias, special leads should automatically turn on;
- the presence of a device for defibrillation and its manual control;
- monitoring heart activity for a long time with recording the results in the memory of the device;
- the ability to make an ECG for several patients and the simultaneous recording of these data in the device's memory;
- remote control.
Single Channel Devices
They are used in almost all public and private health care facilities and ambulance services. Such a portable electrocardiograph has a weight of up to 1 kg. The device has a built-in mini-printer that provides ECG data to thermal paper. It is possible to automatically determine the diagnosis. Such an ECG device can operate from a network or from a built-in battery.
There are even smaller models (about 800 g) that are popular among paramedics. It is possible to record a small amount of data in the device memory for ECG. The price of single-channel devices is in the range of 22-30 thousand rubles.
Three-channel devices
Such electrocardiographs are endowed with a thermal printer and three-channel output of the research results. They have the following features:
- calculations are carried out automatically, control of the device is not needed;
- the thermal printer has a significant expansion, allowing, in addition to graphic data of the electrocardiogram, to indicate personal information about the patient, the used electrostatic precipitator, the level of increase in the amplitude of the study;
- the results can be transferred to a personal computer to calculate additional indicators;
- there is the possibility of defibrillation.
The cost of three-channel electrocardiographs is in the range of 50 thousand rubles.
Six channel devices
Such an ECG apparatus has a wider scope. Employees of rescue services, military hospitals, ambulance services, private clinics use it. ECG removal is possible on two types of six-channel devices: portable (portable) and computer.
Features:
- storing in memory about 1000 examination results (in the presence of a hard disk with 10 GB);
- the ability to examine 150 patients without recharging the device;
- high speed printing, which is carried out automatically;
- the ability to use multiple paper sizes to record results.
Among other things, such an ECG device, the price of which is within 75 thousand rubles, shows the status of the device: battery charge, memory, disconnecting electrodes, gives a warning about the imminent end of the paper.
12 channel electrocardiographs
Used in orthopedics, therapy, surgery, in emergency conditions, during the rehabilitation period after surgical interventions, during physiotherapy manipulations. Removing the ECG on such an apparatus has a lot of advantages. The device allows you to make hourly data recording for one patient, enter data about the patient, and also control the electrocardiograph from a computer.
An interesting point is that you can drive these norms, and if deviations are determined during the examination, the device will give a signal about violations. An ECG allows you to set, which consists of the following elements:
- electrocardiograph;
- a computer that can communicate with the ECG device through a wired or wireless connection;
- a printer that allows you to print data on the results of diagnostics;
- bicycle ergometer - a device with which you can evaluate the work of the heart muscle with a load, connects to the electrocardiograph via Bluetooth;
- software.
The cost of twelve-channel devices ranges from 100 to 500 thousand rubles, which depends on the country of manufacture and the configuration of the kit.
Conducting research
To measure the potential difference, disposable electrodes for ECG are used, which are superimposed on certain parts of the body. A gel is applied to the fixation area, which improves the conductivity of the skin. So they do it now, and before they used gauze napkins soaked in salt water.
Heart muscle cells are small electrical generators that charge and discharge when an excitation wave sets in. An electrocardiogram is the final indicator of the functional abilities of these generators, reflecting the distribution of electrical impulses in the heart.
What does the doctor see on the cardiogram?
Typically, the following indicators can be determined on an ECG:
- P wave - is a reflection of atrial depolarization.
- QRS is a complex denoting ventricular depolarization.
- ST and T wave - repolarization of the ventricles.
- Wave U - specialists have different opinions about its purpose. Some believe that the wave is due to the repolarization of Purkinje fibers, while others talk about the penetration of potassium into the heart cells during the relaxation period.
It is important to know about the location of the leads, due to which the potential difference is measured. The first three leads are placed on the extremities (a red electrode on the right arm, yellow on the left, green on the left leg). A black electrode is placed on the right leg, which does not measure indicators, but is grounding.
Chest leads on which electrodes for ECG are applied (disposable):
- V1 - the right edge of the sternum in the 4th intercostal space;
- V2 - the left edge of the sternum in the 4th intercostal space;
- V3 - in the middle between V2 and V4;
- V4 - mid-clavicular line in the 5th intercostal space;
- V5 - along the front axillary line at the intersection with the horizontal level of V4;
- V6 - along the mid-axillary line at the intersection with the horizontal level of V4;
- V7 - along the rear axillary line at the intersection with the horizontal level of V4;
- V8 - along the mid-scapular line at the intersection with the horizontal level of V4;
- V9 - along the paravertebral line at the intersection with the horizontal level V4.
Other ECG methods
There are a significant number of techniques. For example, electrocardiography through the esophagus. An electrode is inserted into the lumen of the esophagus in an active form. This method is informative for various heart block.
Vector cardiography is a diagnostic method that allows you to fix the electrical vector of the functionality of the heart muscle in the form of a projection of three-dimensional figures on a flat surface.
Daily monitoring according to Holter is an assessment of the work of the heart muscle in dynamics over a long time. A positive aspect is the possibility of carrying it out not only in stationary but also at home. At the end of the diagnosis, the data is transferred to a computer, where they are already being studied by a doctor.
Gastrocardiomonitoring - there is a simultaneous fixation of ECG and gastrogram data for 24 hours. Together with the device for electrocardiography, a nasogastric tube is administered to the patient through which data on acidity in the esophagus or stomach are obtained.
Medicine in general and cardiology in particular are not standing still. Every year, diagnostic equipment is being improved, transforming into advantages those moments that were previously shortcomings.