Cardiology
Arrhythmias
Cardiology

Arrhythmias

AFib, AVB, SVT, VT, WPW, torsades.

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◆Atrial fibrillation

  • •Rate control first-line: beta-blocker OR non-DHP CCB (diltiazem/verapamil if asthma/COPD)
  • •Unstable (hypotension/AMS/chest pain/shock): synchronized cardioversion
  • •Stroke prevention: CHA₂DS₂-VASc ≥2 (M) or ≥3 (F) → DOAC (apixaban, rivaroxaban)
  • •Warfarin for mechanical valves or severe MS
  • •Young + AFib + weight loss + palpitations → check TSH (hyperthyroidism)

◆AV blocks

  • •1st degree (PR >200): asymptomatic = reassurance
  • •Mobitz I (progressive lengthening): usually no pacemaker
  • •Mobitz II + 3rd degree: pacemaker
  • •Inferior MI + complete AV dissociation: temporary pacemaker (often resolves)

◆SVT (narrow QRS)

  • •Stable regular: vagal maneuvers → adenosine 6 mg, then 12 mg
  • •Irregular (AFib/aflutter): rate control
  • •Unstable: synchronized cardioversion

◆VT (wide QRS)

  • •Stable VT: IV amiodarone or lidocaine
  • •Unstable VT: synchronized cardioversion
  • •Pulseless VT/VF: defibrillation + ACLS
  • •Wide QRS in older patient with CAD = assume VT
  • •Old MI + sudden syncope = ventricular arrhythmia (scar-related re-entry)

◆Torsades de pointes

  • •Polymorphic VT + prolonged QT
  • •Triggers: macrolides, fluoroquinolones, methadone, haloperidol, TCAs, antiarrhythmics, hypoK/Mg/Ca
  • •Treat: IV magnesium (even if Mg normal)
  • •Unstable → defibrillate

◆WPW

  • •Delta wave + short PR + wide QRS at baseline
  • •AFib in WPW: AVOID AV nodal blockers (BB, CCB, digoxin, adenosine) → procainamide or ibutilide; cardiovert if unstable
  • •Definitive: catheter ablation of accessory pathway

◆Sinus bradycardia

  • •Symptomatic: atropine first
  • •BB overdose: IV glucagon (↑cAMP independent of BB)
  • •CCB overdose: IV calcium + glucagon
  • •Digoxin toxicity: digoxin immune Fab
  • •Refractory: transcutaneous → transvenous pacing
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