Adenosine for supraventricular tachycardia, amiodarone broadly, digoxin for rate control
Expansion
Supraventricular tachycardia: vagal manoeuvres, then adenosine 6 mg then 12 mg. Causes a transient sense of impending doom and flushing. Contraindicated in asthma; potentiated by dipyridamole and blocked by theophylline.
Atrial fibrillation
- Rate control first line for most: beta blocker or rate-limiting calcium channel blocker; digoxin for sedentary patients or heart failure
- Rhythm control: flecainide (only if no structural heart disease, since it is proarrhythmic after infarction), amiodarone if structural disease
- Anticoagulation based on CHA2DS2-VASc, independent of the rate or rhythm strategy
Ventricular tachycardia: amiodarone; lidocaine as an alternative.
Amiodarone toxicity is extensive and worth knowing as a list: thyroid (both directions), pulmonary fibrosis, hepatitis, corneal microdeposits, slate-grey skin discolouration, photosensitivity, peripheral neuropathy, and a half-life of about 50 days. It is also a potent enzyme inhibitor, raising digoxin and warfarin levels.
Torsades de pointes is treated with magnesium, and any QT-prolonging drug must be stopped.