What is the treatment for tachycardia in pregnancy?

Treatment of Tachycardia in Pregnancy

For acute tachycardia in pregnancy, begin with vagal maneuvers, followed by IV adenosine if unsuccessful, then IV metoprolol if adenosine fails; proceed immediately to synchronized cardioversion if the patient is hemodynamically unstable. 1, 2, 3

Acute Management Algorithm

Step 1: Assess Hemodynamic Stability

• If hemodynamically unstable (hypotension, altered mental status, chest pain, acute heart failure): Proceed directly to synchronized cardioversion 1, 2
• If hemodynamically stable: Follow stepwise pharmacologic approach 1, 2, 3

Step 2: First-Line Intervention for Stable Patients

Vagal maneuvers should be attempted first 1, 2, 3:

• Valsalva maneuver: Patient bears down against closed glottis for 10-30 seconds, generating at least 30-40 mmHg pressure, performed in supine position 1
• Carotid sinus massage: Apply steady pressure over carotid sinus for 5-10 seconds after confirming absence of bruit 1
• Ice-cold wet towel to face (diving reflex) 1
• These maneuvers only work if the arrhythmia involves the AV node as part of a reentrant circuit 1

Step 3: Second-Line Pharmacologic Treatment

Adenosine IV if vagal maneuvers fail 1, 2, 3:

• Initial dose: 6 mg rapid IV bolus 1
• If ineffective: Up to two subsequent 12 mg doses 1
• Safe up to 24 mg in some cases 1
• Extremely short half-life means minimal fetal exposure 1
• Maternal side effects (chest discomfort, flushing) are transient 1
• Terminates approximately 30% of atrial tachycardias 2

Step 4: Third-Line Pharmacologic Treatment

IV metoprolol or propranolol if adenosine fails or is contraindicated 1, 2, 3:

• Beta-blockers have extensive safety data from decades of use in pregnancy for various maternal conditions 1
• Slow infusion preferred to minimize hypotension risk 1
• Cardioselective beta-blockers (metoprolol) are first-line for prophylaxis 3

Step 5: Electrical Cardioversion

Synchronized cardioversion for hemodynamically unstable patients or when pharmacologic therapy fails 1, 2, 3:

• Safe at all stages of pregnancy 1
• Position electrode pads to direct energy trajectory away from uterus 1
• Perform fetal monitoring during and immediately after cardioversion if time allows 1
• Use same energy dosing as non-pregnant patients 1

Chronic/Prophylactic Management

First-Line Agents

• Digoxin or cardioselective beta-blocker (metoprolol) for rate control and prophylaxis 2
• Beta-blockers are considered first-line for various arrhythmias in pregnancy due to extensive safety data 1

Second-Line Agents

• Sotalol, flecainida, or propafenona if first-line agents fail 2
• Flecainide particularly effective for fetal supraventricular tachycardia with hydrops 4

Critical Contraindications

• Never use AV nodal blocking agents in patients with manifest pre-excitation on resting ECG 2
• Amiodarone should only be used when all other therapies have failed, at lowest effective dose, due to fetotoxic effects including congenital abnormalities 2, 4, 5

Important Timing Considerations

Avoid all medications in first trimester if possible 1:

• Risk of congenital malformations is greatest during first trimester 1
• Beta-blockers may cause intrauterine growth retardation if given in first trimester 4
• Use lowest recommended dose with regular clinical monitoring 1

Special Situations

Atrial Fibrillation/Flutter

• Therapeutic anticoagulation with HBPM or vitamin K antagonists depending on gestational age 2
• Rate control with beta-blockers or digoxin 5
• Electrical cardioversion generally not recommended for focal atrial tachycardia due to high recurrence 2

Ventricular Tachycardia

• IV lidocaine or procainamide for acute termination 5
• Electrical cardioversion if hemodynamically unstable 3
• Rare unless structural heart disease or hyperthyroidism present 2

Refractory Cases

• Catheter ablation should be considered only for drug-resistant, poorly tolerated cases 2
• Preferably performed with zero-fluoroscopy technique 6
• Sometimes delivery of viable fetus is the best therapeutic option 6

Common Pitfalls to Avoid

• Do not routinely discontinue chronic beta-blocker therapy before major surgery or delivery, as this increases risk of rebound ischemia 7
• Do not use beta-blockers alone in pheochromocytoma without alpha-blockade first 7
• Monitor for bradycardia when using metoprolol, especially in patients with first-degree AV block or conduction disorders 7
• Beta-blockers may mask hypoglycemia in diabetic patients, though dizziness and sweating remain 7