What is the management for a pregnant patient in the 2nd trimester with Supraventricular Tachycardia (SVT)?

Management of SVT in Pregnant Patients During the Second Trimester

For pregnant patients in the second trimester with supraventricular tachycardia (SVT), the first-line treatment should be vagal maneuvers, followed by adenosine if necessary, with beta-blockers or cardioversion reserved for refractory cases. 1, 2

Acute Management Algorithm

First-Line Interventions:

• Vagal maneuvers should be performed with the patient in the supine position as the initial intervention 2, 1
  • Valsalva maneuver: Patient bears down against closed glottis for 10-30 seconds (equivalent to 30-40 mmHg) 2
  • Carotid sinus massage: Apply steady pressure over carotid sinus for 5-10 seconds after confirming absence of bruits 2
  • Cold stimulus: Applying an ice-cold, wet towel to the face 2
  • Note: Valsalva is more successful than carotid sinus massage 2, 1
  • Avoid eyeball pressure as it is potentially dangerous 2, 1

Second-Line Interventions (if vagal maneuvers fail):

• Adenosine is the first-line pharmacological option 2
  • Initial dose: 6 mg rapid IV bolus
  • If ineffective, up to 2 subsequent doses of 12 mg may be administered 2, 1
  • Considered safe during pregnancy due to its short half-life 2, 1
  • Maternal side effects (chest discomfort, flushing) are typically transient 2

Third-Line Interventions:

• Intravenous beta-blockers when adenosine is ineffective or contraindicated 2

  • Metoprolol or propranolol are reasonable options 2
  • Generally considered safe during the second trimester 2
  • Administer as slow infusion to minimize risk of hypotension 2

• Intravenous verapamil may be considered when adenosine and beta-blockers are ineffective or contraindicated 2

  • Higher risk of maternal hypotension compared to adenosine 2
  • Has been used successfully in the third trimester 3

• Intravenous procainamide may be reasonable for acute treatment 2

  • Considered relatively safe for short-term therapy 2

For Hemodynamically Unstable Patients:

• Synchronized cardioversion is recommended 2
  • Safe at all stages of pregnancy 2, 1
  • Apply electrode pads to direct energy trajectory away from uterus 2
  • Fetal monitoring during and after cardioversion is recommended 2
  • Energy dosing should be the same as in non-pregnant patients 2

Ongoing Management Options

Pharmacological Options:

• Metoprolol is a first-line agent for prophylactic therapy 2

  • Class I recommendation with level B evidence 2
  • Extensive safety data from treating various maternal conditions 2

• Propranolol is a reasonable alternative 2

  • Class IIa recommendation with level B evidence 2
  • Generally considered safe in the second trimester 2

• Digoxin is another first-line option 2

  • Class I recommendation with level C evidence 2
  • Long track record of safety during pregnancy 4

• Other options that may be considered include: 2

  • Flecainide (with AV-nodal blocking agents) 2
  • Sotalol 2
  • Propafenone (with AV-nodal blocking agents) 2
  • Verapamil 2

Interventional Options:

• Catheter ablation may be reasonable in pregnant patients with highly symptomatic, recurrent, drug-refractory SVT 2
  • Class IIb recommendation with level C evidence 2
  • Efforts should be made to minimize radiation exposure 2
  • Non-fluoroscopic ablation has been shown to definitively resolve SVT without recurrence 5

Important Considerations and Cautions

• Avoid amiodarone during pregnancy (Class III recommendation) due to potential fetal harm 2
• Avoid atenolol during pregnancy (Class III recommendation) due to risk of intrauterine growth retardation 2
• Flecainide should not be used in patients with significant ventricular dysfunction 2
• In patients with mild symptoms and structurally normal hearts, reassurance without treatment may be sufficient 2
• Antiarrhythmic drugs should only be used if symptoms are intolerable or if tachycardia causes hemodynamic compromise 2
• Use the lowest recommended dose of medications with regular monitoring of clinical response 2, 1
• Physiological changes during pregnancy (increased cardiac output, blood volume, decreased serum protein concentration) can affect drug pharmacokinetics 2

By following this algorithm, clinicians can effectively manage SVT in pregnant patients during the second trimester while minimizing risks to both mother and fetus.