How to Do an ECG test

If you are experiencing chest pain or feeling discomfort in the heart region, you may require an ECG test to determine if all is well with your heart health. A wave tracing is formed due to the electrical activity of the heart.

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It provides important diagnostic information regarding cardiovascular and/or respiratory conditions. Gauze in this blog will provide all information regarding this common diagnostic imaging test, focusing on how is ECG test is performed, and what the ECG test shows.

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When is an ECG Required?

An ECG records how many times the heart beats and how regularly it beats. It gives us information about the narrowing of coronary arteries, a heart attack, or irregular heartbeats

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• Chest pain.

• Breathlessness.

• fatigue or weakness.

• feeling of pounding, racing, or fluttering heart.

• lightheadedness or confusion.

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These are some common experiences that one can have, which suggest an underlying disease process. They highlight the need for investigating the cause. Always consult your family doctor before an ECG. It assumes much more significance if your family has a history of cardiovascular diseases.

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Types of ECG

Cardiovascular diseases are significant health concerns worldwide. The ECG helps doctors diagnose issues early and prevent serious health risks. Whether you need a resting ECG or a stress test ECG depends on the symptoms you have. There are three types of ECG tests.

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Resting ECG

The resting ECG is a commonly done test that has the following advantages.

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• Quick.

• Non-invasive.

• Simple.

• An easily available test. 

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It can be done in the shortest time while you are lying down.

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It identifies

• irregular heartbeats.

• past heart attacks.

• an enlarged heart.

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The test is usually done using a 12-lead ECG, which presents a detailed view of the heart's electrical activity from different angles. It is a simple test that gives valuable information about how your heart is doing at rest.

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Stress or exercise ECG (Treadmill test)

It is done while you are walking on a treadmill or cycling on a stationary bike the goal is to see your hearts activity is under stress it provides information on coronary artery diseases It provides information on coronary artery disease which is when your hot arteries are blocked the stress ECG helps doctors understand how hot performs when you are active.

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Ambulatory ECG (24-hour Holter monitor)

The ambulatory ECG or halter monitor is worn for 24 hours or even longer while you go about your normal daily routine. The small ECG recorder tracks your heart’s activity throughout the day. A 24-hour ambulatory ECG test detects rhythm problems, which may be occasional.

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How Does an ECG Work?

Principle on which the ECG works: When a muscle contracts, it generates an electric current, which is detected and measured through electrodes placed on the body. Electrical and chemical signals are used by nerves and muscles in our body to communicate with each other. The electrical system in the heart, a muscular organ, records the patterns on the ECG. Cells in the heart generate electrical impulses that spread throughout the muscular organ.

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The signals start from the sinoatrial node in the right atrium and spread throughout the heart, causing it to beat. The electrodes connected to the ECG machine with leads sense the heart's electrical activity and record it, producing a waveform on a tracing sheet. Doctors use this waveform to diagnose cardiovascular conditions and abnormalities in the heart. 

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What to Expect During an ECG

Before an ECG, wear clothes that are easy to remove and comfortable. Small electrodes are placed on your chest, which record the activity of your heart. Movements during the ECG affect the results. The electrodes sense the heart's electrical activity and create a continuous waveform. The ECG takes only a few minutes, the mild discomfort can occur while the electrodes are removed. 

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Preparation

For the ECG test, wear loose and comfortable clothing, avoid wearing tight clothes, as they are difficult to remove, and you need to expose your chest. Avoid applying oil solutions or cream to your chest area.

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The hair on a man’s chest needs to be removed as the hair interferes and the electrodes and prevents them from sticking to the chest properly. Inform the doctor about the medicines you are taking because some affect the ECG. Eat a light meal before an ECG.

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Step-by-Step Procedure for ECG

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Do the preliminaries

Wear the patient protective gear and introduce yourself. Before proceeding with the test, confirm the patient’s name and date of birth. The whole process should be explained to the patient in a language that he understands.

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If the patient is a female, then she should be chaperoned by a female staff member. After taking consent from the patient, adequately expose the chest for the procedure.

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Set up the equipment

Before starting the ECG, the machine is connected to the leads, calibrated to record the electric impulses from the heart. Connect the wires to the machine for proper function, taking all precautions to connect the right leads to the right place. Once set up, the ECG can be recorded, taking all precautions.

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Electrode placement

A 12-lead ECG involves the use of ten electrodes, six on the chest and four on the limbs. Each electrode must be secure and have a good contact with the skin, as loose electrodes give faulty results.

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Chest electrodes and lead placement

Check the expiry of the electrodes and apply the six electrodes in the following locations.

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• V1 is placed at the 4th intercostal space to the right of the sternum.

• V2 is placed at the 4^th intercostal space to the left of the sternum.

• V3 is placed midway between the V2 and V4 electrodes.

• V4 is placed at the fifth intercostal space in the middle of the clavicular line.

• V5 is placed at the left anterior axillary line at the level of V4.

• V6 is placed on the left mid auxiliary line at the same horizontal level as V4 and V5.

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After all the electrodes have been placed, they should be attached to the associated chess league with the cable.

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Limb electrode and lead placement

The four color-coded limb electrodes are placed in the following locations.

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• Red (RA) at the right forearm proximal to the wrist.

• Yellow (LA) left forearm proximal to the wrist.

• Green (LL) left lower leg proximal to the ankle.

• Black (RL) right lower leg proximal to the ankle.

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They should be placed in areas with no adipose tissue, major muscles, or bony prominences after attaching all electrodes and connecting the associated limb leads with the cable. The mnemonic Ride Your Green Bike reminds the placement of the limb leads starting clockwise from the right wrist.

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Conducting the test

Once the electrodes are correctly positioned, the test can begin. The patient is asked to relax, lie still, and breathe normally. The ECG machine will record the heart’s electrical activity during the time within no time.

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Recording the data

The machine records the electrical signals transmitted by the heart, and it is recorded on the graph paper.

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Completing the test and removing the electrode

After completing the ECG, remove the electrodes from the patient's skin. Wipe the skin and remove adhesive residue. Detach the ECG leads from the electrode. Record all the patient's details on the ECG as:

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• Name.

• Age.

• Date.

• Hospital ID number.

• Document the findings.

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The patient can return to his normal activities as the test is non-invasive and has no recovery time. The recorded data is then sent to a cardiologist or healthcare provider for analysis and interpretation.

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Analysing the results

After the test is completed, a cardiologist analyses and interprets the data. Heart’s rhythm and abnormalities (if any) are identified by a trained professional, depending on the wave size, shape, and direction.

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Factors that Impact the ECG Trace Quality

• Muscle movement: Can create artefacts on an ECG.

• Electrical continuity: Any break in a cable or lead wire that isn’t properly plugged can cause improper results.

• Electrodes: Use fresh and good-quality electrodes to ensure contact with the skin.

• Broken cables and lead wires prevent a quality ECG.

• Interference with: Unwanted artifacts on the ECG trace from nearby services such as power cords, infusion pumps, ventilators and noise affects the ECG.

• Equipment: monitor settings also impact the trace quality.

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Conclusion

An ECG can be done within ten minutes by an experienced technician. For accurate readings, it should be done carefully, and good-quality equipment must be used. Gauze helps healthcare professionals and patients to interpret ECG results and ensure accuracy.