Atrial flutter

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⚠️ Important: Class I & III antiarrhythmics ❌ should NOT be given until the ventricular rate is controlled with digoxin, beta-blockers, or calcium channel blockers. These drugs can slow atrial flutter → risk of dangerous 1:1 conduction ⚡. ✅ Catheter ablation (targeting the re-entrant circuit) = >90% success in preventing recurrence.

ℹ️ About Atrial Flutter

• ⚡ Atrial rate: 280–350 bpm.
• 🧐 Suspect flutter if ventricular rate ~150 bpm, especially with no accessory pathway.
• 🔄 Frequently alternates with atrial fibrillation (AF–flutter).

🧬 Aetiology

• 🔁 Macro-reentrant arrhythmia, usually in the right atrium.
• Can occur in normal hearts or with underlying cardiac/systemic disease.
• Risk factors: prior AF, HTN, CAD, valvular heart disease.

📈 ECG Appearances

🔎 ECG Findings

• 🪚 Sawtooth pattern (best in II, III, aVF).
• 1️⃣:1️⃣ AV conduction → 300 bpm 🚨 (rare, life-threatening).
• 2️⃣:1️⃣ block → 150 bpm (most common).
• 3️⃣:1️⃣ → 100 bpm | 4️⃣:1️⃣ → 75 bpm.
• 👂 Carotid massage or adenosine can unmask flutter waves.

📊 Types

• Type I (Typical): 🔁 Circuit around tricuspid annulus (cavo-tricuspid isthmus).
• Type II (Atypical): Non-isthmus dependent, often post-surgery/ablation.

🩺 Causes

• Idiopathic, PE, ASD, IHD, HTN, cardiomyopathy.
• COPD, post-cardiac surgery, pericarditis.
• Thyrotoxicosis, alcohol intoxication 🍺 (“holiday heart”).

🤒 Clinical Presentation

• 😐 Asymptomatic if rate well controlled.
• Palpitations, fatigue, SOB, dizziness, lightheadedness.
• 🚨 Severe: haemodynamic collapse, syncope, heart failure.

🔬 Investigations

• 🧪 Bloods: FBC, U&E, TFTs, CRP, troponin, BNP.
• 📈 ECG: Classic sawtooth pattern. Adenosine may help unmask.
• 🩻 Echo: LV function, atrial size, valve disease.
• 📟 Holter: Intermittent flutter detection.

🛠️ Management

• ⚡ Synchronized DC cardioversion: First-line if unstable.
• 🎛️ Rate control: β-blockers, CCBs, or digoxin.
• 🔄 Rhythm control: Amiodarone/flecainide (⚠️ only with AV nodal blocker to avoid 1:1).
• 🔥 Catheter ablation: Gold standard, >90% success.
• 🛡️ Anticoagulation: Use CHA₂DS₂-VASc to guide.
• 🌱 Lifestyle: limit alcohol, treat COPD, thyroid disease, HTN.

🚫 Contraindicated Drugs

• Class I (flecainide, propafenone): ❌ Risk of 1:1 conduction → ventricular rates up to 300 bpm.
• Class III (amiodarone, sotalol): ❌ Same risk if AV node not blocked.

⚠️ Use With Caution

• 💊 β-blockers: Good for rate control, but may cause bradycardia/hypotension if overdosed.
• 💊 Non-DHP CCBs (verapamil, diltiazem): Avoid in systolic HF due to negative inotropy.

📚 References

• Atrial Flutter, Typical & Atypical: A Review
• 2019 AHA/ACC/HRS Guidelines for Atrial Arrhythmias

🩺 Case 1 - Symptomatic Atrial Flutter

A 66-year-old man presents with palpitations and mild breathlessness. Pulse is regular at 150 bpm. ECG shows a “saw-tooth” baseline pattern in the inferior leads with atrial rate around 300 and ventricular rate 150 (2:1 block). Management: ⚡ Rate control with beta-blocker or diltiazem; rhythm control often considered as flutter responds well to DC cardioversion or catheter ablation. Anticoagulation according to CHA₂DS₂-VASc. Avoid: ❌ Using digoxin alone in young/active patients (less effective for exertional rate control). Avoid class IC drugs (flecainide) if structural heart disease present.

🩺 Case 2 - Atrial Flutter in Heart Failure

A 78-year-old woman with known dilated cardiomyopathy presents with worsening ankle swelling, breathlessness, and palpitations. Pulse is 120 bpm and irregularly regular. ECG shows atrial flutter with variable block. Management: 💊 Careful rate control (digoxin may be useful in HF), diuretics for congestion, anticoagulation as indicated. Consider catheter ablation for definitive therapy if recurrent. Avoid: ❌ Verapamil or diltiazem in decompensated HF (negative inotropy). Avoid delaying anticoagulation - stroke risk similar to AF.