What is an Electrocardiogram?
An electrocardiogram (EKG or ECG) is a simple, quick, painless test that records the electrical activity of your heart. Every time your heart beats, an electrical signal travels through the heart, causing it to contract and pump blood. An EKG captures these electrical signals and displays them as waves on a graph.
This test is one of the most common heart tests and is often part of routine physical exams. It provides valuable information about your heart's rhythm, rate, and overall health. EKGs can detect a variety of heart conditions, from minor irregularities to life-threatening problems.
Types of EKG Tests
Several types of EKG tests are available, depending on what information your doctor needs:
Common Types
- Resting EKG: The standard test performed while you lie still, taking only a few minutes
- Holter Monitor: A portable EKG device worn for 24-48 hours to record your heart rhythm during daily activities
- Event Monitor: Similar to a Holter monitor but worn for weeks or months, recording only when you activate it or when it detects abnormal rhythms
- Stress EKG: Performed during exercise to see how your heart responds to physical activity
- Signal-Averaged EKG: A more detailed analysis used to detect subtle rhythm problems
Why You Might Need This Test
Doctors order EKGs for many reasons, including:
- To investigate symptoms like chest pain, palpitations, or shortness of breath
- To check for irregular heartbeats (arrhythmias)
- To determine if heart disease is causing symptoms
- To evaluate how well heart medications or pacemakers are working
- To check heart health before surgery
- To monitor changes in heart conditions over time
- To detect a heart attack (current or previous)
- To assess heart damage from conditions like high blood pressure
- As part of routine health screenings, especially for people with risk factors
- To check for electrolyte imbalances that can affect the heart
- To evaluate the effects of certain medications on the heart
Preparing for Your EKG
Preparation for a resting EKG is minimal and straightforward:
- No fasting or special diet is required
- Continue taking your regular medications unless told otherwise
- Avoid applying lotions, oils, or powder to your chest on the day of the test
- Wear comfortable clothing with easy access to your chest, arms, and legs
- Let your doctor know about all medications and supplements you're taking
- Inform your doctor if you're allergic to adhesive or tape
- Try to stay calm and relax—anxiety can affect your heart rate
What to Expect During the Test
A resting EKG is quick, easy, and completely painless. Here's what typically happens:
The Procedure
- Duration: The entire process takes about 5-10 minutes, with the actual recording lasting only a few seconds
- Position: You'll lie flat on an exam table
- Skin preparation: The technician may clean and slightly rub your skin where electrodes will be placed
- Electrode placement: Small sticky patches (electrodes) are attached to your chest, arms, and legs—usually 10-12 electrodes total
- No chest hair: If you have chest hair, a small area may need to be shaved for better electrode contact
- Stay still: You'll need to lie very still and breathe normally during the recording
- No talking: You may be asked not to talk during the test
- Recording: The machine records your heart's electrical activity for several seconds
- Completion: Electrodes are removed, and the test is complete
After the Test
After an EKG, you can immediately resume all normal activities. There are no side effects or recovery time needed. You may have some minor skin irritation where the electrodes were placed, which should go away quickly.
Your doctor will review the EKG tracing and discuss the results with you, either immediately or at a follow-up appointment. The EKG provides instant results, so in emergency situations, doctors can interpret it right away.
Understanding Your Results
An EKG provides information about several aspects of your heart's function:
- Heart rate: Whether your heart beats too fast, too slow, or at a normal rate
- Heart rhythm: Whether your heartbeat is regular or irregular
- Heart attack: Signs of current or past heart attack
- Blood flow: Whether blood flow to the heart is reduced
- Heart enlargement: Whether heart chambers are enlarged or thickened
- Electrolyte problems: Abnormal levels of potassium, calcium, or magnesium
- Medication effects: How certain medications are affecting your heart
- Electrical conduction: How well electrical signals travel through the heart
Interpreting Results
Normal results mean your heart's electrical activity appears regular and normal. Abnormal results don't always mean you have a serious heart problem—many factors can affect an EKG, and your doctor will consider your symptoms and medical history when interpreting results.
What EKG Can Detect
While EKGs are very useful, it's important to understand their capabilities and limitations. An EKG can detect:
- Heart attacks (current and previous)
- Arrhythmias (irregular heart rhythms)
- Heart enlargement
- Poor blood flow to the heart muscle
- Electrolyte imbalances
EKG Limitations
However, an EKG cannot:
- Predict future heart attacks
- Detect all heart problems—some conditions only show symptoms intermittently
- Assess how well heart valves are working
- Show blockages in coronary arteries unless they're causing active problems
When Additional Testing Is Needed
If your EKG is normal but you have symptoms, your doctor may recommend additional tests like a stress test, echocardiogram, or Holter monitor for a more complete evaluation.
Common EKG Findings
Some common abnormalities that may be found on an EKG include:
- Sinus tachycardia: Fast heart rate (over 100 beats per minute at rest)
- Sinus bradycardia: Slow heart rate (under 60 beats per minute)
- Atrial fibrillation: Irregular, often rapid heart rhythm
- Premature beats: Extra heartbeats that occur earlier than normal
- Bundle branch block: Delay in electrical signal conduction
- ST-segment changes: May indicate heart attack or reduced blood flow
Understanding Your Findings
Your doctor will explain what any abnormal findings mean for your specific situation and whether treatment is needed.
Safety and Risks
An EKG is completely safe with no risks. The test only records electrical activity—it doesn't send electricity through your body. There's no risk of electric shock. The only potential minor issue is slight skin irritation from the adhesive electrodes, which resolves quickly.
Even people with pacemakers or implantable defibrillators can safely have EKGs. The test is safe for people of all ages, including newborns and elderly patients.