Overview of Electrocardiogram
An electrocardiogram, often abbreviated as ECG or EKG, is a simple test that keeps track of your heart’s electrical activity. It’s performed from outside your body, so it’s completely painless and non-invasive. The test gets its name from the German term ‘elektro-kardiographie.’ It was invented by a Dutch doctor named Einthovan in 1902. After a decade of research, the medical community began to understand how useful the test could be.
Many heart-related conditions, like irregular heart rhythms (arrhythmias), chest pain (angina), and hardened arteries (atherosclerosis), could be spotted using an ECG by 1910. Because of these pioneering efforts, William Einthoven is often referred to as the “father of electrocardiography.” He was awarded the Nobel Prize in Medicine in 1924 for his work, which laid the groundwork for this essential heart disease detection technique. Today, ECG tests are commonly used in medical facilities all over the world.
An ECG is a valuable tool for exploring severe heart diseases. Its use has grown over time; today, it’s used to monitor patients taking certain medications, check patients who are going to have surgery that’s not related to the heart, and screen people who work in high-risk jobs or play sports. It’s also employed in research settings to monitor the effects of certain drugs on the heart.
Given that heart diseases are the leading cause of death, healthcare providers need to be skilled at interpreting ECG results. Doing so can result in a faster diagnosis and treatment. However, it’s important to remember that reading an ECG can be complex, and mistakes can lead to false diagnosis and delay appropriate treatment. Therefore, this information aims to provide a basic understanding of how ECG works, how to interpret its results, and what common ECG findings might mean.
Anatomy and Physiology of Electrocardiogram
To understand heart tests like the electrocardiogram (ECG), you first need to know a bit about how your heart is structured and how it works. Your heart is an essential organ located in the middle of your chest between your lungs. It’s a part of your circulatory system, which also includes blood vessels and blood.
Your heart is made up of four chambers: two upper ones called atria and two lower ones called ventricles. The right atrium and ventricle are separated from the left atrium and ventricle by a muscle wall known as the septum. The heart’s job is to pump blood around your body. It takes in blood that has little oxygen left from your body through two large veins, then the blood goes to the right atrium. From there, it goes to the right ventricle and then to your lungs via two large pulmonary arteries. While in your lungs, your blood receives a fresh supply of oxygen. This oxygenated blood then returns to the left atrium of your heart via the pulmonary veins. From the left atrium, the blood is pumped by the left ventricle into the aorta, a large artery, and sent out to supply your body. The heart itself gets its blood from arteries known as coronary arteries, which branch off from the aorta.
There are two main coronary arteries, right and left, running on the surface of your heart. They branch into smaller arteries to supply blood to different areas of your heart. These areas have specific names:
* Inferior Wall – Supplied by the Right coronary artery
* Anteroseptal – Supplied by the Left anterior descending artery
* Anteroapical – Supplied by the far end of the Left anterior descending artery
* Anterolateral – Supplied by the Circumflex artery
* Posterior Wall – Supplied by the Right coronary artery
This information is crucial because an ECG uses 12 leads, or viewpoints, to examine these specific regions of your heart. The ECG can help doctors identify areas that might be strained due to lack of oxygen (ischemia) or damaged from lack of blood flow (infarction).
Beyond anatomy, understanding the heart’s electrical system is equally important. Your heart is made of specialized muscle cells arranged in a specific pattern. These cells, connected end-to-end, contract in waves that allow your heart to pump blood effectively. This contraction is controlled by your heart’s electrical conduction system which consists of pacemaker cells and non-pacemaker cells. The pacemaker cells, located mainly in the sinoatrial (SA) and atrioventricular (AV) nodes of your heart, set the rate and rhythm of your heartbeats. The non-pacemaker cells, which make up the majority of your heart muscle, contribute to triggering and transmitting electrical signals that keep your heart beating regularly.
Understanding which ECG leads correspond to which arteries helps doctors pinpoint where a possible blockage might be, especially in cases of serious heart attacks. All of this helps doctors determine the best course of action for your heart health.
Why do People Need Electrocardiogram
The development of electrocardiograms (ECGs) from basic to modern-day computerized machines has made them a go-to device for diagnosing various heart-related problems.
In simpler words, an ECG is a test that checks how your heart is working. It can be used in a broad range of medical situations, including when you’re feeling unwell or have symptoms that could be linked to your heart. Some of such symptoms could include feelings of a fast heartbeat, dizziness, blue discoloration of the skin, chest discomfort, fainting episodes, seizures, or even poisoning.
ECGs can help doctors identify signs of heart disease, such as too fast or too slow heartbeats, and conditions like low body temperature, a heart murmur (an unusual sound during heartbeat), shock, low or high blood pressure. It can also detect heart muscle injury, reduced blood supply to the heart (ischemia), and signs of prior heart attacks.
If you have something known as Rheumatic heart disease, which is a complication of Rheumatic fever, ECGs can find any related changes. It could also note changes that are significant in diagnosing the right treatment for cases such as drowning or electrocution.
ECGs are handy if you have a pacemaker or a defibrillator (devices to manage irregular heart rhythms). It can check these devices for any malfunctions, evaluate programming, verify their rhythm analysis, and ensure that they are correctly pacing electrical signals in the heart.
If you suffer from any metabolic disorders or have had a heart trauma, an ECG can assist with the assessment. It is invaluable during a CPR (Cardiopulmonary Resuscitation — a lifesaving technique used during heart emergencies). It also aids in studying and diagnosing heart diseases from birth (congenital heart diseases).
ECGs can detect imbalances in the body’s electrolyte levels and rhythm disorders. They are used to monitor the effect of drug therapies and their side effects. During surgeries, ECGs have immense utility; for example, in pre-surgery assessments, during the operation, and postoperative monitoring.
Athletes often get an ECG done as part of their routine physical exam. It helps rule out a condition called cardiomyopathy, where the heart muscle becomes enlarged or thick.
When a Person Should Avoid Electrocardiogram
An electrocardiogram, often called an EKG or ECG, is a test that measures the electrical activity of your heart. There’s no reason a person can’t have this test from a medical standpoint. That said, there are a couple of mild reasons why it might not be suitable:
A patient might say no to the test. It’s always the individual’s decision whether they want the procedure or not.
Also, some people are allergic to the sticky material that’s used to attach the leads (these are little wires that pass the heart’s electrical signals to the EKG machine) to their body. If you have this allergy, you might not be able to have an EKG.
Equipment used for Electrocardiogram
The American College of Cardiology (ACC), the American Heart Association (AHA), and the Heart Rhythm Society (HRS), have all collaborated to create guidelines and standards for ECG (electrocardiogram) machines. Thanks to modern technology, most ECG machines are digital and can come up with an initial analysis based on certain pattern criteria.
A standard ECG machine consists of 12 leads or wires, split into two groups – limb leads and chest (precordial) leads. The limb leads are further divided into standard bipolar limb leads (I, II, and III) and so-called augmented unipolar leads (aVL, aVF, and aVR). The chest leads consist of V1 to V6. The limb leads focus on the heart from a straight-on perspective, while the chest leads record the heart’s electrical activity from a side view. The ECG itself is a graphical display of the heart’s electrical pulses, traced on special ECG paper.
The basic principle behind the ECG recording is that electricity, or more specifically electromagnetic force, has both magnitude and direction. When an electrical force (or what we call a “depolarization” current) travels towards the electrode or wire, it is recorded as a positive wave on the ECG. When it travels away from the electrode, it appears as a negative wave.
There are several types of ECG monitoring machines available, such as continuous ECG monitoring, hardwire cardiac monitoring, telemetry (which allows for monitoring from a distance), ambulatory electrocardiography, transtelephonic monitoring, wireless mobile cardiac monitoring systems, etc. You can even find combinations of an ECG and electronic stethoscopes in one handheld device, that can assess heart rhythms at the bedside. Today’s technology has even made wristwatches that can monitor your heart rate and rhythm, which have been particularly good at detecting an irregular heartbeat measurable as atrial fibrillation. However, these wristwatch devices might be a bit less accurate than a full, 12-lead ECG. If they detect something abnormal, you’ll need to have those results confirmed by standardized clinical testing. This testing is typically done in a cardiology office.
The tools you need to perform a standard, 12-lead ECG includes:
– Electrodes (which are sensors),
– Gauze and skin cleaning (often alcohol) solution,
– Razors, clippers, or tape (for removing hair),
– Skin adhesive and/or antiperspirant,
– ECG-specific paper,
– Cardiac monitor or ECG machine.
Who is needed to perform Electrocardiogram?
Anyone in the medical field who has been taught how to do an electrocardiogram (ECG) – a test that checks how your heart is working – can carry out this test. This includes doctors, nurses, and specially trained technicians. The test is usually done by technicians in places like clinics or hospitals, and the results are then looked at and interpreted (or understood) by your healthcare provider. To make sure the results are accurate, a heart specialist, known as a cardiologist, often double-checks them if you are in a hospital setting.
Preparing for Electrocardiogram
When having an electrocardiogram, which is a test to measure the electrical activity of the heart, there are certain steps that need to be done to prepare. First, the doctor will ask about any medications you are on and if you have any allergies related to a specific type of sticky gel used in the procedure. This is important to ensure you won’t have an allergic reaction during the test.
The room temperature should be comfortable to prevent you from feeling cold and shaking which could interfere with the test results. You will be asked to wear a special gown and the areas on your chest where the electrodes (small sticky sensors) will be placed will be identified. Because a good connection between these sensors and your skin is necessary for the test, you might need to have some chest hair shaved. A special adhesive gel is then applied to these sensors that helps them stick on your skin and pick up the electric signals from your heart.
Before the test begins, you’ll be required to remove any metallic items such as jewelry or watches, as these can interfere with the testing equipment. It’s crucial that the sensors are correctly placed on certain areas of your arms, legs and chest so that the correct information can be obtained from your heart.
Once everything is set, you’ll need to lie down and relax. The test itself involves recording the electric signals of your heart for a short period of about 10 seconds. It’s important to stay as calm and relaxed as possible during this time to ensure accurate results.
How is Electrocardiogram performed
An electrocardiogram, also known as an EKG or ECG, is a device that records your heart’s electrical activity. It does this by drawing a line on a moving piece of special paper. This machine moves at a speed of 25 mm/sec. On the graph that gets printed out, time is represented on the horizontal axis (across), and voltage (the ‘strength’ of your heart’s electrical signals) is represented on the vertical axis (up and down). A complete second is represented by five large squares across the graph, and each large square is divided into five smaller squares.
For a standard 12-lead ECG, there are six leads, or wires, attached to your limbs and another six leads attached to your chest. These leads are color-coded to make sure they don’t get mixed up (red – right arm, yellow – left arm, green – left leg, and black – right leg). The placement of the chest leads is very specific:
- V1 is positioned to the right of your breastbone, while V2 is placed on the left side of your breastbone.
- V4 is placed on the line running vertically from the middle of your collarbone, directly in line with the fifth rib space. It is important that V4 is placed before V3.
- V3 is then positioned between V2 and V4, and V5 is placed directly between V4 and V6.
- V6 is positioned in line with the fifth rib space on the side of your body, in the middle of your underarm area.
This positioning ensures that the leads V4, V5, and V6 align horizontally along the fifth rib space. This proper placement helps your doctor get a good look at what’s happening with your heart.
Possible Complications of Electrocardiogram
An electrocardiogram, often called an EKG or ECG, is a test that’s super safe and doesn’t hurt at all. It’s non-invasive, meaning it doesn’t involve any needles, cuts, or anything that might cause pain. Additionally, it doesn’t generally have any major risks or complications. In some cases, people can have an allergic reaction or skin sensitivity to the sticky gel that’s used to attach the electrode patches. However, these problems typically go away once the patches are removed and usually don’t need any treatment.
However, it’s worth noting that the test could potentially provide inaccurate results if there are any distortions or artifacts, which are like “blips” or disruptions in the EKG signals. If these distortions aren’t considered, it might lead to wrong conclusions about your heart’s health, which could then lead to inappropriate treatment.
Also, there’s a small chance of misdiagnosis if the EKG leads, which are the wires connected to the electrode patches, are accidentally placed in the wrong spots. This could affect the accuracy of the test results.
What Else Should I Know About Electrocardiogram?
An electrocardiogram (ECG) is a test that checks how your heart is functioning by analyzing the electrical signals it produces. By studying the waves and time intervals on an ECG, doctors can find out if they’re normal or if they indicate heart disease.
A typical way to interpret an ECG involves analyzing:
1. Rate: This involves figuring out the number of times your heart is beating per minute. If your heart rate is less than 60, it’s slow and referred to as bradycardia. When it’s more than 100, it’s fast and termed as tachycardia.
2. Rhythm: This is about understanding the regularity and pattern of your heartbeat. The ECG may reflect different irregularities, like atrial fibrillation, an irregular rhythm caused by rapid heart activity.
3. Cardiac Axis: It shows the direction of the electrical activity in the heart. An abnormal axis can point to heart conditions like left or right ventricular hypertrophy (an enlarged heart chamber), inferior myocardial infarction (damage to the lower part of the heart), or even certain lung diseases.
4. P-wave: This wave signifies the electrical activity when the upper part of your heart (atria) contracts. An abnormal P wave may indicate enlarged atria, a condition when the upper heart chambers are larger than they should be.
5. PR Interval: This shows the time it takes for electrical signals to travel from the upper to the lower heart chambers. A longer or shorter interval can indicate specific heart conditions.
A heart block happens when the electrical signals in the heart are delayed or blocked. This can occur at different levels – the sinus node (where the heart’s electrical impulses start), the atrioventricular node (the junction box that distributes the signal to the lower heart chambers), or the bundle branches (the pathways leading to the heart muscle). There are different types of blocks, and recognizing these on an ECG is crucial for deciding the right treatment.
