What is the management approach for a pregnant woman with a short PR interval, specifically in conditions like Wolff-Parkinson-White (WPW) syndrome?

Management of Short PR Interval During Pregnancy: Focus on Wolff-Parkinson-White Syndrome

Pregnant women with a short PR interval, particularly those with Wolff-Parkinson-White (WPW) syndrome, require close monitoring by a specialized cardio-obstetrics team with prompt investigation if symptoms of palpitations or presyncope develop. 1

Understanding Short PR Interval in Pregnancy

A short PR interval on ECG (less than 120 ms) with a delta wave indicates the presence of an accessory pathway between the atria and ventricles, bypassing the normal conduction system. This is the hallmark of WPW syndrome, which can lead to:

• Supraventricular tachycardias (SVTs)
• Atrial fibrillation with rapid ventricular response
• Risk of sudden cardiac death in rare cases

Risk Assessment

The risk stratification for pregnant women with WPW syndrome should include:

1. Symptom evaluation:

   • History of palpitations, dizziness, syncope
   • Frequency and duration of tachycardia episodes

2. ECG characteristics:

   • Presence of delta wave
   • PR interval duration
   • QRS complex morphology

3. Associated conditions:

   • Ebstein's anomaly (common association) 1
   • Other congenital heart defects
   • Family history of sudden death

Management Algorithm

Preconception

For women with known WPW syndrome planning pregnancy:

• Consider catheter ablation of the accessory pathway before pregnancy if symptomatic
• Risk stratification with electrophysiology study if indicated

During Pregnancy

1. Asymptomatic patients with incidental short PR interval:

   • Regular cardiac monitoring
   • Patient education about warning symptoms
   • No specific treatment required

2. For symptomatic patients:

   a) First-line management for acute SVT:

   • Vagal maneuvers
   • IV adenosine if vagal maneuvers fail
   • β-blockers are considered relatively safe in pregnancy 1

   b) For recurrent symptomatic episodes:

   • Oral β-blockers (metoprolol, propranolol) for prevention
   • Avoid digoxin in patients with WPW as it may accelerate conduction through the accessory pathway

   c) For atrial fibrillation with rapid conduction:

   • IV procainamide or IV amiodarone in emergency situations
   • Immediate DC cardioversion if hemodynamically unstable

3. For refractory cases:

   • Catheter ablation can be considered during pregnancy (preferably in second trimester) with appropriate shielding to minimize radiation exposure

Delivery Planning

• Vaginal delivery is preferred in stable patients
• Continuous cardiac monitoring during labor and delivery
• Epidural anesthesia is generally well-tolerated
• Avoid medications that may precipitate arrhythmias
• Have emergency medications and defibrillator readily available

Special Considerations

1. Ebstein's anomaly: WPW syndrome is commonly associated with Ebstein's anomaly, which may complicate pregnancy management 1

2. Risk of transmission: Counsel patients about the potential genetic risk to offspring

3. Fetal monitoring: Regular fetal assessment is essential, particularly if maternal arrhythmias occur

4. Postpartum period: Increased vigilance as hemodynamic changes during this period may trigger arrhythmias

Potential Pitfalls

1. Misdiagnosis: Short PR interval may be misinterpreted as normal variant or other conditions

2. Inappropriate medication: Avoid drugs that enhance conduction through the accessory pathway (digoxin, verapamil, diltiazem)

3. Underestimating risk: Even previously asymptomatic patients can develop significant arrhythmias during pregnancy due to hemodynamic changes

4. Delayed intervention: Failure to promptly address symptomatic arrhythmias can lead to maternal and fetal compromise

Follow-up Recommendations

• Monthly cardiac evaluation during pregnancy
• ECG at each visit
• Prompt evaluation for any new symptoms
• Consider 24-hour Holter monitoring if symptoms suggest intermittent arrhythmias

By following this structured approach to management, the risks associated with short PR interval and WPW syndrome during pregnancy can be effectively minimized, optimizing both maternal and fetal outcomes.