💓 Men's Health
ECG (Electrocardiogram) Explained
What an ECG shows, what to expect, and how to understand basic results
An electrocardiogram (ECG or EKG) is a painless, non-invasive test that records the electrical activity of the heart. Small electrodes are attached to the chest, arms, and legs — the ECG machine records 12 'views' of the heart's electrical system, showing each heartbeat's rate, rhythm, and the sequence of electrical activation through different heart chambers. In Nigeria, ECG is available at most secondary and tertiary hospitals and is increasingly available at private clinics. It is essential for diagnosing heart attacks, arrhythmias, hypertensive heart disease, and conduction problems.
Signs and Symptoms
✓ ECG ordered for: chest pain, palpitations, breathlessness, dizziness, blackouts, before surgery, monitoring known heart conditions, hypertension follow-up, drug monitoring (some medications prolong the QT interval)
✓ The test takes 5–10 minutes. Lie still — movement creates artefact
✓ No preparation required. Remove jewellery from wrists. Chest hair may need to be shaved for electrode contact
When to Seek Help
Chest pain with ECG changesST elevation in multiple leads = STEMI (heart attack) — needs emergency treatment within 90 minutes
ECG shows very fast or very slow rate with symptomsHeart rate > 150 or < 40 with symptoms = haemodynamic compromise — needs emergency evaluation
Prolonged QT interval (> 450ms men, > 470ms women)Risk of life-threatening arrhythmia (Torsades de Pointes). Review medications — many drugs prolong QT
Atrial fibrillation detectedIrregularly irregular rhythm — may need anticoagulation to prevent stroke
New left bundle branch block (LBBB) with chest painTreat as STEMI equivalent — emergency
Tests & Diagnosis
🧪 Heart rate
Normal 60–100 bpm. Fast (tachycardia > 100 bpm) = anxiety, pain, dehydration, fever, anaemia, hyperthyroidism, arrhythmia. Slow (bradycardia < 60 bpm) = athletic, hypothyroidism, heart block, beta-blockers
🧪 Rhythm
Regular vs. irregular. Irregularly irregular rhythm = atrial fibrillation (AF) — most common sustained arrhythmia, significant stroke risk. Regularly irregular = ectopic beats (often benign)
🧪 P wave
Represents atrial activation. Absent P waves = atrial fibrillation. Abnormal P wave shape = atrial enlargement (hypertension, valve disease)
🧪 PR interval
Normal 120–200ms. Prolonged PR (> 200ms) = first-degree heart block (benign in isolation, may be drug-related). Very short PR = pre-excitation (WPW syndrome — risk of fast arrhythmias)
🧪 QRS complex
Represents ventricular (main pumping chamber) activation. Normal < 120ms. Wide QRS (≥ 120ms) = bundle branch block, ventricular ectopic beats, hyperkalaemia
🧪 ST segment
Most clinically important. ST elevation = heart attack (STEMI) or pericarditis. ST depression = ischaemia (angina, NSTEMI), digoxin effect. Normal ST = isoelectric (flat)
🧪 QT interval
Normal 350–450ms. Prolonged QT = risk of fatal arrhythmia. Caused by electrolyte imbalance (low potassium, magnesium), drugs (antipsychotics, antihistamines, certain antibiotics like erythromycin), congenital long QT syndrome
🧪 Left ventricular hypertrophy (LVH)
Tall QRS voltages in specific leads — sign of the heart working harder than normal. Most common cause in Nigeria: long-standing untreated hypertension. Indicates organ damage from hypertension
Frequently Asked Questions
My ECG was normal — does that mean my heart is healthy?
A normal resting ECG is reassuring but does not exclude all heart problems. Exercise ECG (stress test), echocardiogram (heart ultrasound), or coronary CT angiogram may be needed depending on your symptoms and risk factors. A normal ECG during chest pain does not rule out angina or even a heart attack (approximately 15% of NSTEMIs have a normal initial ECG).
What does 'left ventricular hypertrophy' on my ECG mean?
It means the muscle of your heart's main pumping chamber has thickened — most commonly from years of high blood pressure making the heart work harder. It is an important warning sign: it means hypertension has already caused organ damage and blood pressure control needs to be more aggressive. Treatment can partly reverse LVH.
Is an ECG painful?
No. The electrodes simply stick to the skin and measure electrical signals — no electricity is passed through the body. The test is completely painless. The only discomfort is removing electrode stickers from chest hair.
How often should I have an ECG?
There is no recommended routine ECG interval for healthy people without symptoms. ECG is indicated when you have cardiac symptoms (palpitations, chest pain, dizziness, blackouts), before surgery, when starting medications that affect cardiac conduction, and as part of follow-up for known heart disease or hypertension with suspected LVH.