What is the workup for a fetus diagnosed with mitral valve regurgitation at 20 weeks gestation?

Workup for Fetal Mitral Valve Regurgitation at 20 Weeks Gestation

A fetus diagnosed with mitral valve regurgitation at 20 weeks gestation should be referred to a tertiary care center with a dedicated Heart Valve Team for comprehensive fetal echocardiography and serial monitoring to assess for signs of hemodynamic compromise. 1

Initial Comprehensive Fetal Echocardiography

Fetal echocardiography is the cornerstone of evaluation and should include:

• Assessment of mitral valve anatomy and function:

  • Quantification of regurgitation severity using color and pulsed Doppler 1
  • Measurement of ventricular dimensions, wall thickness, and valve annuli with comparison to gestational age norms (z-scores) 1
  • Evaluation of other valvular structures for associated abnormalities

• Hemodynamic assessment:

  • Cardiothoracic ratio (normal: 0.25-0.35 using area, <0.5 using circumference) 1
  • Ventricular wall fractional shortening (normal >28%) 1
  • Myocardial performance index (Tei index) for global ventricular function 1
  • Atrioventricular inflow and ductus venosus Doppler patterns 1
  • Assessment for retrograde flow in the aortic isthmus 1

• Evaluation for high-risk features:

  • Left atrial dilation 2
  • Restrictive atrial septum 2
  • Ascending aortic Z-score (values <-1.3 associated with worse outcomes) 2
  • Presence of hydrops fetalis 1, 2
  • Associated cardiac defects, particularly aortic valve stenosis or atresia 2

Risk Stratification

Based on the initial assessment, risk stratification should be performed:

1. High-risk features requiring more intensive monitoring:

   • Moderate to severe mitral regurgitation with left atrial dilation
   • Restrictive atrial septum
   • Small ascending aorta (Z-score <-1.3)
   • Presence of hydrops
   • Associated cardiac defects (particularly aortic valve stenosis/atresia)

2. Moderate risk features:

   • Moderate mitral regurgitation without left atrial dilation
   • Normal atrial septum
   • Normal ascending aorta size

Serial Monitoring Protocol

• High-risk fetuses:

  • Fetal echocardiography every 2-4 weeks 1
  • Consider calculation of the Cardiovascular Profile Score (CVPS) at each visit 1
  • Monitor for development of hydrops, worsening regurgitation, or ventricular dysfunction

• Moderate-risk fetuses:

  • Fetal echocardiography every 4 weeks 1
  • More frequent monitoring if progression is noted

Multidisciplinary Management

• Heart Valve Team involvement:

  • Maternal-fetal medicine specialist
  • Pediatric cardiologist with expertise in fetal echocardiography
  • Pediatric cardiac surgeon
  • Neonatologist
  • Genetic counselor (for associated genetic syndromes)

• Genetic evaluation:

  • Consider amniocentesis if not already performed
  • Chromosomal microarray analysis
  • Evaluation for associated syndromes

Delivery Planning

• Timing and mode of delivery:

  • Plan for delivery at a tertiary care center with pediatric cardiac capabilities
  • Vaginal delivery may be considered for cases without severe hemodynamic compromise 1
  • Cesarean section should be considered for fetuses with severe hemodynamic compromise 1

• Immediate postnatal evaluation:

  • Echocardiography within 24 hours of birth
  • Assessment for progression of regurgitation (occurs in approximately 22% of cases) 3

Counseling Points

• Mortality risk is significant with moderate to severe mitral regurgitation in the fetus (discharge mortality reported at 55% in one study) 2
• Risk is substantially higher with:
  • Left atrial dilation
  • Restrictive atrial septum
  • Smaller ascending aorta
  • Associated cardiac defects, particularly aortic valve abnormalities 2

Potential Interventions

• Fetal cardiac intervention:
  • May be considered in select cases, particularly with associated aortic stenosis 2
  • Should only be performed at specialized centers with expertise in fetal cardiac intervention
  • Discharge mortality with fetal cardiac intervention was 38% in one study 2

Important Caveats

• Avoid ACE inhibitors and ARBs in the pregnant mother as these are contraindicated due to fetal toxicity 1
• The period between 20-28 weeks appears to be the safest for any potential interventions if required 1
• Isolated congenital mitral regurgitation is uncommon; thorough evaluation for associated cardiac defects is essential 4
• In approximately 60% of cases, congenital mitral valve anomalies occur with other cardiac lesions 4