Electrocardiography - a method of studying the work of the heart muscle. With the help of an ECG device, the generated electric fields are recorded with further display of the results in the form of a graphic image on thermal paper (in most cases). The first ECG machine recorded data on film, then there were ink recorders. If the device is completely electronic, then the data can be stored in the computer's memory.
Use of electrocardiographs
An electrocardiography procedure is performed for the following purposes:
- determining the frequency and regularity of contractions of the heart muscle;
- if you need to determine the presence of coronary disease or heart attack;
- if you need to confirm or refute the presence of electrolyte deficiency;
- clarification of the presence of heart blocks;
- evaluation of the state in dynamics during testing with a load;
- if you need to clarify the anatomical and physiological features of the heart (for example, left ventricular hypertrophy);
- if you need to confirm or refute the development of pulmonary embolism;
- for preventive purposes during the periodmedical examination of the population.
Modern devices
Even 20-30 years ago, the ECG machine was an immense machine that 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.
The ECG device can record one or several channels at the same time, on which the division into groups is based. In addition, it must be equipped with certain software:
- syndromic conclusion based on the results of the data obtained;
- in case of heart rhythm disturbances, special leads should automatically turn on;
- presence of a defibrillation device and its manual control;
- monitoring of heart activity for a long time with recording the results in the memory of the device;
- possibility to make an ECG for several patients and simultaneous recording of these data in the memory of the device;
- remote control.
Single-channel devices
Used in almost all public and private medical institutions, ambulance services. Such a portable electrocardiograph has a weight of up to 1 kg. A mini-printer is built into the device, which issues ECG data on thermal paper. It is possible to automatically determine the diagnosis. Such an ECG machine can operate from the mains or from the built-in battery.
There are even smaller models (about 800 g) thatare popular among paramedics. It is possible to record a small amount of data in the memory of the ECG device. 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 research results. Features:
- calculations are carried out automatically, control of the device is not needed;
- The thermal printer has a significant expansion that allows, in addition to graphic data of the electrocardiogram, to indicate personal information about the patient, the electrofilter used, the level of increase in the amplitude of the study;
- results can be transferred to a personal computer to calculate additional indicators;
- there is a possibility of defibrillation.
The cost of three-channel electrocardiographs is within 50 thousand rubles.
Six-channel devices
This ECG machine has a wider scope. It is used by employees of rescue services, military hospitals, ambulance services, private clinics. ECG recording is possible on two types of six-channel devices: portable (portable) and computer.
Features:
- memory about 1000 examination results (10 GB hard disk available);
- the ability to examine 150 patients without recharging the device;
- high-speed printing, which is carried out automatically;
- possibility 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, disconnection of electrodes, issues a warning about the imminent end of the paper.
Twelve-channel electrocardiographs
Used in orthopedics, therapy, surgery, in emergencies, during the rehabilitation period after surgical interventions, during physiotherapeutic manipulations. Removing an ECG on such a device has a lot of advantages. The device allows you to record data for one hour for one patient, enter data about the patient, and also control the electrocardiograph from a computer.
An interesting point is that you can drive in these norms, and if deviations are detected during the examination, the device will give a signal about violations. Making an ECG allows a set that consists of the following elements:
- electrocardiograph;
- computer that can communicate with an ECG device via wired or wireless communication;
- printer for printing diagnostic data;
- veloergometer - a device with which you can evaluate the work of the heart muscle with a load, connects to an electrocardiograph via Bluetooth;
- software.
The cost of twelve-channel devices ranges from 100 to 500 thousand rubles, depending on the countrymanufacturer and kit configuration.
Conducting research
To measure the potential difference, disposable ECG electrodes are used, which are applied to certain areas of the body. A gel is applied to the fixation area, which improves the conductivity of the skin. This is how they do it now, but before they used gauze napkins soaked in s alt water.
Cells of the heart muscle are small electrical generators that are charged and discharged when a wave of excitation occurs. An electrocardiogram is the final measure of the functional abilities of these generators, showing the distribution of electrical impulses in the heart.
What does the doctor see on the cardiogram?
Usually, the following indicators can be determined on the ECG:
- P wave - is a reflection of atrial depolarization.
- QRS - complex indicating ventricular depolarization.
- ST and T wave - ventricular repolarization.
- Wave U - experts have different opinions about its purpose. Some believe that the wave is due to the repolarization of the Purkinje fibers, 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, thanks to which the potential difference is measured. The first three leads are applied to the limbs (red electrode on the right hand, yellow on the left, green on the left leg). A black electrode is placed on the right leg, which does not measure indicators, but isgrounding.
Chest leads with ECG electrodes (disposable):
- V1 - right edge of the sternum in the 4th intercostal space;
- V2 - left edge of the sternum in the 4th intercostal space;
- V3 - midway between V2 and V4;
- V4 - mid-clavicular line in the 5th intercostal space;
- V5 - along the anterior axillary line at the intersection with the horizontal level V4;
- V6 - along the midaxillary line at the intersection with the horizontal level V4;
- V7 - along the posterior axillary line at the intersection with the horizontal level V4;
- V8 - along the mid-scapular line at the intersection with the horizontal level 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 active electrode is inserted into the lumen of the esophagus. This method is informative for various heart blocks.
Vectorcardiography 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.
24-hour Holter monitoring - assessment of the work of the heart muscle in dynamics over a long period of time. A positive point is the possibility of its implementation not only in stationary, but also at home. At the end of the diagnostics, the data is transferred to a computer, where they are already being studied by a doctor.
Gastrocardiomonitoring -there is a simultaneous fixation of ECG data and gastrogram for 24 hours. Together with the device for electrocardiography, a nasogastric tube is inserted into the patient, through which data on acidity in the esophagus or stomach are obtained.
Medicine in general and cardiology in particular do not stand still. Every year, diagnostic equipment is being improved, transforming into advantages those moments that used to be disadvantages.
