Makindo Medical Notes

💡 ECGs for the MLA Medical students should be able to recognise key ECG patterns in acute and chronic disease, linking them to underlying pathology and urgent management steps.

❤️ Acute Coronary Syndromes

• STEMI: Localised ST elevation in ≥2 contiguous leads ± reciprocal ST depression.
• NSTEMI/Unstable angina: ST depression, T-wave inversion, or normal ECG with symptoms.
• Hyperacute T waves: Earliest sign of MI, tall peaked T-waves before ST elevation.
• Old MI: Pathological Q waves (deep, >40 ms wide).

⚡ Arrhythmias

• Atrial fibrillation (AF): Irregularly irregular rhythm, absent P waves, fibrillatory baseline.
• Atrial flutter: Saw-tooth flutter waves, often with 2:1 block (ventricular rate ~150).
• Supraventricular tachycardia (SVT): Narrow complex tachycardia, regular, often no visible P waves.
• Ventricular tachycardia (VT): Broad complex tachycardia, regular, “capture/fusion” beats.
• Ventricular fibrillation (VF): Chaotic irregular waveform, no organised complexes — cardiac arrest rhythm.
• Torsades de pointes: Polymorphic VT with twisting QRS axis; associated with prolonged QT.

⏱️ Conduction Blocks

• First-degree AV block: PR >200 ms, every P followed by QRS.
• Second-degree AV block Mobitz I (Wenckebach): Progressive PR lengthening → dropped beat.
• Second-degree AV block Mobitz II: Intermittent dropped QRS with fixed PR — risk of complete block.
• Third-degree (complete) heart block: No relation between P waves and QRS; escape rhythm.
• Bundle branch blocks: – LBBB: “WiLLiaM” — W in V1, M in V6. – RBBB: “MaRRoW” — M in V1, W in V6.

🧪 Electrolyte & Drug Effects

• Hyperkalaemia: Tall tented T waves, flattened P waves, widened QRS → sine wave (pre-terminal).
• Hypokalaemia: U waves, flattened T waves, prolonged QT.
• Digoxin effect: Down-sloping ST depression (“reverse tick”), flattened T waves.

🩺 Other Must-Know Patterns

• Pericarditis: Widespread concave ST elevation + PR depression.
• STEMI mimics: LBBB, LVH strain pattern, pericarditis.
• Wolff–Parkinson–White (WPW): Short PR, delta wave, widened QRS.
• Long QT syndrome: QTc >440 ms (men) / >460 ms (women).
• Pulmonary embolism: S1Q3T3 pattern (rare, non-specific); sinus tachycardia most common finding.

⚠️ Red Flag ECGs in Exams

• STEMI → immediate reperfusion (PCI/thrombolysis).
• VT/VF → cardiac arrest protocols (defibrillation).
• Complete heart block with syncope → pacing needed.
• Hyperkalaemia with ECG changes → IV calcium, urgent treatment.
• Torsades de pointes → IV magnesium, stop QT-prolonging drugs.

📚 Teaching Pearls

• Always read ECGs systematically: Rate, Rhythm, Axis, Intervals, Morphology, ST/T changes.
• In MLA exams, you’re often asked: “What is the diagnosis?” or “What is the next step in management?”.
• Focus on life-threatening and common patterns, not rare syndromes.