What is the management approach for a pregnant patient with an S3 or S4 (third or fourth heart sound) murmur or splitting?

Management of S3 or S4 Heart Sounds and Splitting During Pregnancy

Third and fourth heart sounds (S3 and S4) and splitting of heart sounds are normal physiological findings during pregnancy and typically do not require specific management unless associated with underlying cardiac pathology.

Normal Cardiovascular Changes in Pregnancy

During pregnancy, several cardiovascular adaptations occur that can produce normal heart sounds that might be concerning in non-pregnant patients:

• Third heart sounds (S3) are present in most pregnant women due to increased blood volume and cardiac output 1
• Physiologic splitting of S2 is common and may widen or appear fixed during later stages of pregnancy 1
• Soft grade 1-2 midsystolic murmurs along the mid to upper left sternal edge are frequent findings 1
• The precordial impulse becomes hyperkinetic, and the first heart sound may be louder with prominent splitting 1

Diagnostic Approach

When evaluating heart sounds during pregnancy:

1. Determine if findings are physiologic vs. pathologic:

   • Normal findings: Isolated S3, physiologic splitting of S2, soft systolic murmur (grade 1-2/6)
   • Concerning findings: S3 with other signs of heart failure, diastolic murmurs, loud (grade ≥3/6) systolic murmurs

2. Echocardiography indications:

   • Echocardiography is recommended for assessment of changes in hemodynamic severity and LV function in patients with known valvular heart disease during pregnancy (Class I recommendation) 1
   • Diastolic murmurs (not due to cervical venous hum or mammary souffle) warrant echocardiographic evaluation 2
   • Abnormal physical findings such as parasternal lift suggesting right ventricular hypertrophy require assessment 2

3. Distinguish from other sounds:

   • Cervical venous hum: Best appreciated in right supraclavicular fossa, can be obliterated by chin movement toward stethoscope or digital pressure over jugular vein 1
   • Mammary souffle: Systolic or continuous sound over engorged breast, eliminated with firm pressure on stethoscope diaphragm 1

Management Algorithm

1. For physiologic S3, S4, or splitting without other abnormal findings:

   • Reassurance
   • Routine prenatal care
   • No specific cardiac follow-up needed

2. For S3 with signs of heart failure or hemodynamic compromise:

   • Prompt echocardiographic assessment
   • Cardiology consultation
   • Monitor for high-risk conditions (Table 31 in guidelines) 1

3. For new S3 or S4 in patient with known valvular disease:

   • Immediate echocardiographic assessment (Class I recommendation) 1
   • Serial monitoring based on severity:
     • Severe valvular disease: More frequent monitoring
     • Moderate disease: Every 1-2 months during pregnancy
     • Mild disease: Once per trimester

Special Considerations

• Position matters: Inferior vena caval obstruction from a gravid uterus in the supine position can cause hypotension and lightheadedness; symptoms resolve quickly with position change 1
• Murmur intensity changes: Increased blood volume during pregnancy can accentuate murmurs associated with stenotic valve lesions (MS, AS), while regurgitant murmurs (AR, MR) may actually become softer due to lowered systemic vascular resistance 1
• Echocardiographic findings: Normal pregnancy is accompanied by mild ventricular chamber enlargement and physiologic valve regurgitation on Doppler imaging 1

Pitfalls to Avoid

• Over-investigation: Echocardiography is not routinely needed for isolated physiologic heart sounds in the absence of other clinical abnormalities 3
• Under-investigation: Diastolic murmurs are unusual in pregnancy and should always prompt further evaluation 1
• Misinterpretation: Doppler echocardiography is very sensitive and may detect trace or mild valvular regurgitation through structurally normal valves, requiring clinical correlation 2
• Overlooking high-risk conditions: Patients with valvular heart disease may require special attention during pregnancy (see Table 31 in guidelines for high-risk conditions) 1

Remember that the only physical examination finding that reliably excludes severe aortic stenosis is a normally split second heart sound 1, so careful auscultation remains an important clinical skill during pregnancy.