What are the treatment options for cardiac arrhythmia?

Treatment Options for Cardiac Arrhythmias

The treatment of cardiac arrhythmias must be tailored to the specific type of arrhythmia, with pharmacological interventions administered intravenously for life-threatening cases and appropriate monitoring in a controlled environment. 1

Initial Assessment and Management

• Determine if the patient has a pulse and assess hemodynamic stability, checking for adverse signs such as low blood pressure, chest pain, heart failure, or high heart rate 2
• For life-threatening arrhythmias, administer drugs intravenously, always followed by a 20 ml saline bolus to aid delivery to the central circulation 1
• When no venous access is possible, drugs (particularly adrenaline) may be delivered via the endotracheal route in double or triple doses 1

Treatment of Ventricular Arrhythmias

Ventricular Fibrillation (VF)/Pulseless Ventricular Tachycardia (VT)

• Early defibrillation is the primary intervention, with pharmacological treatment considered secondary 1
• For refractory VF/pulseless VT (after 12 DC shocks with appropriate advanced life support), consider antiarrhythmic drugs 1
• Magnesium may be effective for VF/VT, particularly when associated with acute myocardial infarction (8 mmol bolus followed by 2.5 mmol/h infusion) 1

Sustained Ventricular Tachycardia

• For unstable VT with pulse, immediate synchronized DC cardioversion is recommended (100J, 200J, 360J) with prior sedation if the patient is conscious 1, 2
• For stable VT:
  • Lidocaine (lignocaine) is the first-choice antiarrhythmic, given intravenously at 50 mg over 2 minutes, repeated every 5 minutes to a total dose of 200 mg, followed by maintenance infusion at 2 mg/min 1, 2
  • Amiodarone is indicated for VT refractory to lidocaine, given at 5 mg/kg (300 mg) over one hour for stable patients, or over 15 minutes in life-threatening situations 1, 2
  • Bretylium can be used for refractory VT that doesn't respond to other agents (5 mg/kg diluted with 100 ml dextrose, with a possible further dose of 10 mg/kg) 1

Treatment of Supraventricular Arrhythmias

Supraventricular Tachycardia (SVT)

• For hemodynamically unstable patients (hypotensive, in heart failure, experiencing angina, or heart rate >200 beats/min), sedate and treat with cardioversion 1
• For stable patients:
  • First try vagal maneuvers (Valsalva maneuver or unilateral carotid artery pressure if no carotid bruit) 1
  • Adenosine is the drug of choice for AV nodal re-entrant tachyarrhythmias (3 mg rapid bolus with saline flush, then 6 mg if no effect after 1-2 minutes, maximum 12 mg) 1
  • Verapamil (5-10 mg over 60 seconds) can be used for definite SVT but is contraindicated if β-blockers have been taken or in SVTs associated with Wolff-Parkinson-White syndrome 1

Atrial Fibrillation (AF)

• Two main treatment strategies exist: rate control and rhythm control 3
• Rate control is the preferred management option in most patients 4
  • Options include beta-blockers, verapamil, diltiazem, and digoxin 5, 6
  • Current recommendation for strict rate control is a resting heart rate <80 beats per minute, though more lenient control (<110 beats/min) may be acceptable 4
• Rhythm control is an option for patients with persistent symptoms despite rate control 4
  • Amiodarone, disopyramide, flecainide, quinidine, and sotalol can prevent relapse after electrical cardioversion 5
  • Amiodarone is more effective than sotalol and propafenone in restoring and maintaining sinus rhythm 5
• Anticoagulation therapy is essential with both rate and rhythm control strategies to prevent stroke 4

Treatment of Bradyarrhythmias

• Transient bradycardias are common in acute myocardial infarction, particularly inferior MI 1
• For bradycardia <40 beats/min or associated with signs of cardiac failure or type II heart block, treat initially with atropine (0.5 mg up to 3 mg, titrated according to heart rate response) 1
• For patients with pauses >3 seconds, Mobitz type II heart block, type II heart block with anterior MI, or previous asystole, prepare immediately for temporary cardiac pacing 1

Important Considerations and Precautions

• Adenosine must be given in a monitored environment (e.g., critical care unit or emergency department) as it can cause transient complete heart block 1
• Adenosine should not be routinely used in asthmatic patients due to risk of bronchospasm 1
• Verapamil is contraindicated if β-blockers have been taken due to risk of profound bradycardia and hypotension 1
• Verapamil should not be used for SVTs associated with Wolff-Parkinson-White syndrome as it may precipitate VT/VF 1
• Most antiarrhythmic drugs depress myocardial contractility and require careful monitoring, especially in hemodynamically compromised patients 1