An electrocardiogram (ECG or EKG) is a common medical test that many individuals have undergone, whether as part of routine check-ups or for heart-related diagnostics. But what exactly does it assess, and what insights can we get from the ECG curve?

Our body's nerve and muscle cells communicate via electrical and chemical signals, and this includes the electrical signals that regulate our heartbeat. These crucial signals originate from a cluster of cells located in the right atrium of the heart, known as the sinoatrial node (SA node). They propagate as tiny electrical impulses through the heart muscle tissue, coordinating the contractions of the atria and ventricles. Interestingly, the path of these signals through the heart can be detected on the skin's surface. An ECG precisely measures these variations in electrical signals, effectively recording changes in voltage across different areas of the skin and representing them graphically. This resulting graph is referred to as an electrocardiogram, providing valuable information about cardiac activity and health.

What is an Electrocardiogram Test?

When you have symptoms like Chest pain, Dizziness, lightheadedness or confusion, Heart palpitations, Rapid pulse, Shortness of breath, Weakness, fatigue or a decline in ability to exercise your physician may recommend the ECG.

The heart typically produces a steady ECG pattern when it's beating normally. The first peak, known as the P wave, represents the spread of the electrical impulse across the two atria of the heart. This signal triggers the atria to contract, pumping blood into the ventricles, and then they immediately relax. The electrical impulse then continues to the ventricles, which can be seen in the Q, R, and S waves of the ECG, collectively called the QRS complex. These waves correspond to the ventricles contracting. Following the QRS complex, the T wave appears, indicating that the electrical impulse has stopped spreading, and the ventricles are relaxing once again.

ECGs are valuable for detecting heart diseases and irregular heartbeats. Analysing what these patterns look like and how they develop can provide insights into the underlying causes of these conditions.

The heart's electrical activity can be detected on the skin's surface, even on distant areas like the arms and legs. A typical "12-lead ECG" utilizes ten electrodes: six on the chest and one on each lower arm and calf. If excessive body hair is present, these regions may require shaving, but otherwise, no special preparation is necessary. These electrodes are linked to an ECG machine via cables. This machine translates the received signals into an ECG graph and stores the data. Some machines can also produce printed copies of the graphs for analysis.

The results of a 12-lead ECG provide information about the electrical activity of the heart. The ECG measures the heart rate, which is the number of heart beats per minute. It identifies irregular rhythms, such as atrial fibrillation, which can increase the risk of stroke and other heart-related issues. The heart’s electrical axis is determined, even a slight change indicates various cardiac conditions. The ECG also shows any interference or noise that could affect the accuracy of the readings. The 12-lead ECG capitalizes on the uneven transmission of heart signals across the skin. It assesses the signal strength between pairs of electrodes, known as "leads." For instance, one lead is derived from the electrodes on your arms. As the name suggests, a 12-lead ECG measures twelve such leads. By pinpointing irregularities in specific leads, healthcare professionals can determine the location of a myocardial infarction within the heart muscle or identify the origin of a heart rhythm issue, whether it's arising from the left or right ventricle.

Why is the ECG test done?

An electrocardiogram (ECG or EKG) helps in assessing the heart's function. Its primary role is to record the heart's rate (heart rate) and regularity (heart rhythm). This diagnostic test provides essential insights into various aspects of cardiac health, including potential indicators of conditions such as coronary artery narrowing, heart attacks, or irregular heartbeats like atrial fibrillation.

What are the types of ECG performed?

Cardiopulmonary exercise test (CPET):

 A cardiopulmonary exercise test (CPET) is an evaluation done for the cardiopulmonary system. This test is used to detect if there are any cardiac or pulmonary diseases.

Exercise EKG (Stress test): 

A stress test which is also called treadmill test is given while a patient walks on a treadmill or pedals a stationary bicycle to monitor the heart during stress you exercise. Breathing and blood pressure rates are also monitored. A stress test may be used to detect coronary artery disease.

Holter monitor: 

The Holter monitor, an iteration of the electrocardiogram (ECG or EKG), is employed for continuous ECG tracing over a duration of 24 hours or more. It involves the placement of electrodes on specific areas of the chest, arms, and legs. These electrodes, connected to an ECG machine through lead wires, record and interpret the heart's electrical activity. The resulting data is printed for the physician's review and subsequent analysis. Explore additional details about the Holter monitor.

Resting 12-lead EKG: 

The resting 12-lead electrocardiogram (EKG) is the conventional method for assessing your heart's electrical performance. Conducted while you are at rest, this EKG captures the electrical activity of your heart using 12 electrodes (adhesive patches) simultaneously placed on your chest, arms, and legs. It is commonly employed as a proactive measure during routine checkups to screen for potential heart issues before any noticeable symptoms manifest.

 Advanced ECG Machines: 

Advanced ECG machines encompass a diverse array of specialized devices equipped with advanced features designed to improve accuracy, efficiency, and diagnostic capabilities beyond standard ECG recording. These machines integrate technological advancements such as 12-lead ECG systems for comprehensive cardiac assessments, wireless capabilities enabling remote data transmission, and computer-assisted algorithms for enhanced ECG data analysis and interpretation.

 Portable ECG Machines:

Portable ECG machines provide mobility advantages by enabling ECG testing beyond traditional clinical settings. These compact, lightweight, and battery-operated devices are ideal for remote patient monitoring, home care, and ambulatory settings. They offer real-time data during daily activities or specific events, supporting continuous monitoring needs. Additionally, many portable ECG machines feature wireless capabilities for seamless transmission of ECG data to healthcare providers, enhancing convenience and accessibility for both patients and medical professionals.

Usually, there is no immediate post-test care required after an EKG examination. Test results are typically promptly accessible, and your doctor may discuss them with you immediately. On occasion, the doctor might involve a cardiologist. After doing the test if the result shows any signs of these abnormalities, your doctor will go over options to improve your heart’s condition. This may include prescribing medication or suggesting lifestyle changes such as modifying your diet or exercising more.

How Is an Electrocardiogram Done? (Step by step procedure)

Step 1: Prepare for this station with

• Hand sanitizer.
• ECG machine.
• 10 sticky pads for electrodes.
• Occasionally, wipes and/or razor.

Step 2: Start by washing your hands and introducing yourself to the patient to confirm their identity.

Step 3: Explain the procedure and obtain consent, ensuring the patient understands why the test is necessary, especially if for chest pain.

Step 4: Ensure patient comfort; for this test, the patient needs to remove their top, so offer a chaperone.

Step 5: Ensure good skin contact for the ECG pads; remove any hindrances like hair or lotion.

Step 6: Enter patient data accurately into the machine for correct labeling on the ECG report.

Step 7: Use 10 sticky pads: 4 for limb leads and 6 for chest leads, placing them at specific locations detailed below.

Step 8: Attach leads to pads; in Europe, limb leads are colored (red, yellow, green, black).

Step 9: Ask the patient to lie still during recording; note any chest pain experienced during the test on the ECG.

Step 10: Remove leads from pads; provide assistance if needed and offer a tissue due to sticky residue.

Step 11: Allow the patient to dress and express gratitude for their cooperation.

Advantages of ECG testing:

ECG testing offers several advantages in clinical practice:

• ECG testing does not require any incisions or entry into the body, making it safe and comfortable for patients.
• The procedure is relatively quick, usually taking a few minutes to perform, and is generally painless.
• ECGs provide valuable diagnostic information about the heart's electrical activity, helping to detect various cardiac conditions such as arrhythmias, heart attacks (myocardial infarctions), and conduction abnormalities.
• ECGs can be used for continuous monitoring in hospital settings or as portable devices for ambulatory monitoring, allowing for long-term observation of heart function.
• ECGs aid in assessing the risk of cardiovascular disease and guide treatment decisions, such as determining the need for medications, interventions like pacemaker implantation, or further cardiac testing.
• They are commonly used in routine medical check-ups to screen for heart conditions and assess overall cardiac health.
• ECGs play a crucial role in emergency medicine by quickly assessing cardiac function in patients presenting with chest pain, palpitations, or other symptoms suggestive of heart problems.
• ECGs are essential for monitoring patients undergoing treatment for cardiac conditions to evaluate treatment effectiveness and detect any changes in heart function over time.

Limitation of ECG testing:

• An ECG primarily detects electrical activity and cannot directly visualize structural abnormalities, such as valvular heart disease or congenital heart defects.
• It may not capture intermittent or transient arrhythmias or ischemic episodes that occur outside of the brief recording period.
• Some ECG changes can be non-specific and may not clearly indicate a specific cardiac condition, requiring further testing for a definitive diagnosis.
• The quality of the ECG recording can be influenced by the skill and experience of the technician performing the test and the proper placement of electrodes.
• External factors such as patient movement, poor electrode contact, or electrical interference can introduce artifacts that complicate the interpretation of the ECG.
• Certain ECG findings can be normal variants and may not necessarily indicate pathology, potentially leading to overdiagnosis or unnecessary further testing.
• While an ECG can detect current abnormalities, it cannot reliably predict future cardiac events or diseases.
• Factors such as obesity, large breast tissue, or chronic obstructive pulmonary disease (COPD) can affect the quality and accuracy of ECG readings.

ECG vs. EKG

ECG and EKG are terms that refer to the same diagnostic test, the electrocardiogram. ECG is derived from the English term "electrocardiogram," while EKG comes from the German "Elektrokardiogramm." Both terms are used interchangeably and serve to record the electrical activity of the heart, helping healthcare providers diagnose and monitor heart conditions. Despite the different abbreviations, the test and its function remain identical.