Makindo Medical Notes

Arrhythmias are disturbances of cardiac rhythm ⚡, ranging from benign ectopic beats to life-threatening ventricular fibrillation. They result from disordered impulse generation or conduction, and can cause palpitations, syncope, stroke, heart failure, or sudden cardiac death 💔. Management depends on the type of arrhythmia, its haemodynamic impact, and underlying structural or systemic disease.

🔬 Pathophysiology

• Automaticity: Abnormal pacemaker activity from atrial, nodal, or ventricular tissue.
• Triggered activity: Afterdepolarisations (e.g., in long QT, digoxin toxicity).
• Re-entry circuits: Common mechanism in SVT, atrial flutter, and VT.
• Conduction abnormalities: AV nodal disease, bundle branch block, accessory pathways.
• Systemic contributors: Electrolyte imbalance (K⁺, Mg²⁺, Ca²⁺), ischaemia, hypoxia, drugs, thyroid disease.

⚡ Common Types of Arrhythmia

• Atrial Fibrillation (AF) ❤️: Irregularly irregular rhythm; stroke risk ×5.
• Atrial Flutter 🌀: Macro–re-entry tachycardia, sawtooth ECG pattern.
• Supraventricular Tachycardia (SVT) 🚀: AVNRT/AVRT, abrupt onset palpitations.
• Ventricular Tachycardia (VT) ⚠️: Wide-complex, often post-MI, risk of degeneration to VF.
• Ventricular Fibrillation (VF) 💥: Chaotic rhythm, no cardiac output, requires immediate defibrillation.
• Bradyarrhythmias 🐢: Sinus node dysfunction or AV block; risk of syncope/sudden death.
• Premature Beats 💥: PACs and PVCs, benign if isolated but frequent PVCs may cause cardiomyopathy.

📋 Clinical Assessment

• History: Palpitations, dizziness, syncope, chest pain, breathlessness; triggers (alcohol, caffeine, stress).
• Examination: Irregular/fast/slow pulse; signs of HF, murmurs, thyrotoxicosis.
• ECG: Gold standard for rhythm diagnosis; 12-lead whenever possible.
• Ambulatory monitoring: Holter, event recorder, implantable loop recorder.
• Echocardiography: Defines structural substrate (LV function, valves, atrial size).
• Blood tests: U&E, Mg²⁺, Ca²⁺, TFTs, troponin, digoxin level.

🛡️ Management Principles

Step 1: Assess stability Unstable = shock the patient (cardioversion/defibrillation). Stable = consider drugs, vagal manoeuvres, or elective cardioversion.

❤️ Atrial Fibrillation (AF) / Atrial Flutter

• Acute unstable AF/flutter: Immediate synchronised DC cardioversion (up to 3 attempts).
• Rate control (first-line in most, esp. >65 or minimal symptoms): - Beta-blockers (bisoprolol, metoprolol). - Rate-limiting calcium-channel blockers (diltiazem, verapamil). - Digoxin (less effective in high sympathetic tone; use in sedentary/heart failure). - Target resting HR <110 bpm (lenient control, per RACE II trial).
• Rhythm control (younger, symptomatic, first episode): - Pharmacological cardioversion: flecainide, amiodarone. - Electrical cardioversion (sedation required). - Catheter ablation (increasing role, esp. for paroxysmal AF).
• Anticoagulation: - Assess with CHA₂DS₂-VASc (stroke risk) & HAS-BLED (bleeding risk). - DOACs (apixaban, rivaroxaban, dabigatran, edoxaban) are first-line in UK unless contraindicated. - Warfarin if mechanical valve or severe mitral stenosis. - Anticoagulation reduces stroke risk by 60–70%.

🚀 Supraventricular Tachycardia (SVT)

• Stable acute SVT: Vagal manoeuvres (Valsalva, carotid sinus massage with caution).
• If unsuccessful: IV adenosine 6 mg, then 12 mg if needed (contraindicated in asthma).
• Alternatives: IV verapamil or beta-blockers.
• Recurrent SVT: Electrophysiology study + catheter ablation (curative in >90%).

⚠️ Ventricular Tachycardia (VT)

• Unstable VT: Immediate synchronised cardioversion.
• Pulseless VT: Defibrillation + ALS protocol.
• Stable VT: - IV amiodarone (preferred). - Lidocaine alternative if ischaemic.
• Secondary prevention: ICD implantation (reduces sudden cardiac death by ~50%).
• Adjuncts: Beta-blockers, ablation for recurrent VT storm.

💥 Ventricular Fibrillation (VF)

• Immediate defibrillation (unsynchronised shock).
• CPR until defibrillator ready; survival drops 10% per minute delay.
• Adrenaline every 3–5 min; amiodarone 300 mg after 3rd shock.
• Post-resuscitation: ICD, address reversible causes (4 Hs & 4 Ts).

🐢 Bradyarrhythmias

• Acute symptomatic bradycardia: IV atropine 500 µg (repeat up to 3 mg).
• If ineffective: isoprenaline/adrenaline infusion, transcutaneous pacing.
• Long-term: Permanent pacemaker (sinus node disease, Mobitz II, complete AV block).

🤖 Device Therapy

• Pacemaker: Sinus node dysfunction, AV block, symptomatic bradycardia.
• ICD: Survivors of VF/VT arrest, LVEF ≤35% with ischaemic/non-ischaemic cardiomyopathy.
• Cardiac Resynchronisation Therapy (CRT): HF with LVEF ≤35%, QRS ≥130 ms, symptomatic despite optimal medical therapy.

🩺 Additional Considerations

• Correct reversible causes: Electrolytes, hypoxia, thyroid disease, drugs (QT-prolonging agents).
• Lifestyle: Reduce alcohol, caffeine, stimulants; weight loss and BP control reduce AF burden.
• Special populations: - Post-MI patients → beta-blockers, ACE inhibitors, ICD consideration. - Pregnancy → avoid teratogenic drugs (use labetalol, sotalol; avoid amiodarone if possible).

📊 High-Yield Summary Table

Arrhythmia	ECG Features	Acute Management	Long-Term Management
Atrial Fibrillation ❤️	Irregularly irregular, no P waves	Rate/rhythm control, anticoagulation if unstable → DC cardioversion	Rate vs rhythm strategy; anticoagulation; ablation in selected cases
SVT 🚀	Regular, narrow-complex	Vagal manoeuvres → adenosine → cardioversion	Catheter ablation (curative); beta-blockers/CCBs
Ventricular Tachycardia ⚠️	Wide-complex tachycardia	Unstable → cardioversion; Stable → amiodarone	ICD; beta-blockers; ablation for VT storm
Ventricular Fibrillation 💥	Chaotic, no complexes	Defibrillation + CPR + ALS drugs	ICD; secondary prevention
Bradyarrhythmia 🐢	Slow HR, sinus pauses, AV block	Atropine → pacing if unstable	Permanent pacemaker

📝 Conclusion

Arrhythmia management rests on rapid recognition, assessing haemodynamic stability, and tailoring therapy to the arrhythmia mechanism. Always correct reversible factors, use drugs and devices appropriately, and refer for ablation or ICD when indicated. In AF, stroke prevention through anticoagulation is as vital as rhythm control. In VT/VF, ICDs and defibrillation save lives. Understanding both acute and chronic management is key to safe, evidence-based practice.

Disclaimer: Educational content only. Always follow current ESC, AHA, and Resus Council UK guidelines in clinical practice.