Lesson Objectives:

• Differentiate between tachyarrhythmias and bradyarrhythmias.

• Identify life-threatening arrhythmias and their acute management.

• Review the use of antiarrhythmic drugs, cardioversion, and pacemakers.

Tachyarrhythmias: Supraventricular vs. Ventricular

🔹 Supraventricular Tachycardias (SVT)
✔️ Atrial fibrillation (AFib):

• ECG: Irregularly irregular rhythm, no P waves.

• Management:

  • Rate control: Beta-blockers (metoprolol), CCBs (diltiazem).

  • Rhythm control: Antiarrhythmics (amiodarone, flecainide).

  • Stroke prevention: CHA₂DS₂-VASc score for anticoagulation (DOACs, warfarin).

✔️ Atrial flutter:

• ECG: Sawtooth pattern.

• Treatment: Similar to AFib (rate vs. rhythm control).

✔️ Paroxysmal SVT (PSVT):

• ECG: Narrow QRS, regular, fast (~150-250 bpm).

• Management: Vagal maneuvers → Adenosine (6mg IV push) → Beta-blockers/CCBs.

🔹 Ventricular Arrhythmias
✔️ Ventricular tachycardia (VT):

• Sustained (>30 sec) or nonsustained.

• Stable VT: IV amiodarone or procainamide.

• Unstable VT: Synchronized cardioversion.

✔️ Torsades de Pointes (TdP):

• ECG: Polymorphic VT with prolonged QT.

• Treatment: IV magnesium sulfate, defibrillation if unstable.

✔️ Ventricular fibrillation (VFib):

• ECG: Chaotic, irregular rhythm, no pulse.

• Treatment: Immediate defibrillation (unsynchronized shock) + CPR.

Bradyarrhythmias & Conduction Blocks

🔹 Sinus Bradycardia:

• HR <60 bpm, common in athletes, beta-blocker use.

• Symptomatic? Give atropine (0.5 mg IV) or consider pacing.

🔹 AV Blocks:
✔️ 1st-degree AV block: PR >200ms, benign.
✔️ 2nd-degree Mobitz I (Wenckebach): Progressive PR prolongation → dropped beat. Usually benign.
✔️ 2nd-degree Mobitz II: Sudden dropped QRS, no PR prolongation – may progress to complete block, needs pacemaker.
✔️ 3rd-degree AV block: Complete dissociation between P waves & QRS. Requires permanent pacemaker.