Electrocardiography (electro-cardio-graphy = EKG) is a test that records the electrical activity and rhythm of the heart. The medical device used for this test is the EKG device. These devices facilitate the examination of the physician by converting the electrical signals into a graphical form. It can be used both in family health centers and hospitals, as well as in workplace medicine. Recently, EKG devices are used even in homes. Special devices called EKG holters stay connected to the patient for 24 hours and record the electrical activity of the heart. It is often used by cardiologists. There are also devices available in hospitals and cardiology centers where a patient's EKG is tested on a treadmill, known as a cardiac stress test. These are called stress EKGs. It is very important that there is no interference in the test for the correct interpretation of the graphics resulting from the test. EKG devices are very sensitive to electromagnetic fields. For this reason, regardless of the brand model, there is a possibility of interference in the outputs of the devices. The factors that negatively affect the devices can be prevented by some precautions to be taken. The factors that negatively affect EKG devices can be examined under five main headings.
Can Incorrect Placement of Electrodes Cause Incorrect Measurement?
Due to incorrect placement of the ECG electrodes, the direction of the test plot may appear upside down and results may therefore be misinterpreted. Reverse connection of electrodes, especially placed on arms and legs, can cause this condition. After the electrodes are connected, they need to be checked. In addition, the electrodes placed on the chest wall must be positioned correctly. Otherwise, erroneous or parasitic results may occur. Incorrect electrode placement is common. It is a problem that can be easily corrected by returning the electrodes placed on both the chest (V1-V6 electrodes placed on the rib cage) and the extremities to the correct position as soon as the error is noticed.
What are the Conditions Affecting Electrical Activity?
EKG devices, which are based on measuring the electrical activity of the heart, are adversely affected by electromagnetic fields. Especially other equipment in the ECG room and electrical cables inside the wall can disrupt the ECG signals. The thick and vibrating isoelectric line in the graph, which is normally expected to be straight despite the electrodes being connected correctly, indicates that the signals are affected. The isoelectric line is the line that lies between the waves on the EKG chart and is normally a straight line. Since this problem may occur due to other devices connected to wall electrical outlets, devices that do not require continuous use should be unplugged to solve the problem. In addition, performing the test by placing the patient and the ECG device away from other devices can prevent interference. Apart from this, metal accessories on the person undergoing EKG testing may also cause interference. It is beneficial to remove accessories such as belt buckles, rings, necklaces, earrings and watches during the test.
How Does the Activity of Skeletal Muscles Affect the ECG Result?
Electrical signals may be more intense when the person being tested feels uncomfortable, has muscle tension, moves or talks. Moving skeletal muscles can generate electrical signals that can be detected by EKG devices. In addition, muscle vibrations due to Parkinson's disease, anxiety and tremor can also cause parasite formation. Muscle activities in the body can be detected by spike-like or bumpy fluctuations on the isoelectric line. Shifts in the isoelectric line may occur due to the movement of the chest wall during breathing. The fact that the patient does not move or speak makes the test result more accurate.
Does Weak Signal Transmission Affect the EKG Test?
The correctness of the position of the electrodes as well as the skin contact should be sufficient. Otherwise, it may cause interference in the test result. The presence of dirt, oil, sweat, hair or dead skin cells in the area of the electrodes adversely affects the contact. In order to provide better signal transmission, it is necessary to clean the skin and apply sufficient gel to the electrodes. Another reason for poor signal transmission is cables. Cracks and breaks in the cables or electrode cables used in EKG devices adversely affect the signal transmission. Also, tension in cables can cause poor signal transmission. In cases where there is no signal transmission due to the cable, the electrical activity recorded by the electrodes is seen as a dotted line as a result of the test. In this case, checking the cables and electrodes and replacing them if necessary will solve the problem.
How Does the Quality and Durability of the EKG Device Affect the Test Result?
Electronic cards, sensors and accessories on the devices may affect the measurement results. The quality of the software is as important as the hardware of the devices. Some devices prevent interference thanks to algorithms developed as software. Choosing high quality and proven brands prevents many problems that may occur. Especially in second-hand ECG devices, problems with signal transmission can be seen. Interference with these devices may be caused by the device and cables. In particular, the wear of the cables over time can adversely affect the measurement results. For this reason, it is necessary to pay attention to the quality of the device and accessories when buying a second-hand ECG device. Choosing reliable vendors in this regard prevents potential problems.