How are murmurs managed in pregnancy?

Management of Murmurs in Pregnancy

Murmurs in pregnancy should be evaluated based on their characteristics, with physiologic murmurs requiring reassurance only, while diastolic murmurs and loud systolic murmurs (grade ≥3/6) warrant echocardiographic evaluation regardless of symptoms. 1

Physiologic Changes and Murmurs in Pregnancy

Pregnancy causes significant cardiovascular changes that can produce or alter heart murmurs:

• 50% increase in blood volume and cardiac output by mid-pregnancy 1
• Increased heart rate (10-20 beats/minute) and stroke volume 1
• Decreased systemic vascular resistance 1

These hemodynamic changes commonly produce:

1. Soft grade 1-2/6 midsystolic murmur along the mid to upper left sternal edge (most common finding) 2, 1
2. Cervical venous hum in right supraclavicular fossa (can be eliminated by turning chin toward stethoscope) 1
3. Mammary souffle over engorged breast (eliminated with firm pressure on stethoscope) 1

Evaluation Algorithm for Murmurs in Pregnancy

Step 1: Characterize the Murmur

• Timing: Systolic vs. diastolic
• Intensity: Grade 1-6/6
• Location: Left sternal edge, apex, etc.
• Response to maneuvers: Position changes, Valsalva

Step 2: Determine Need for Further Evaluation

Echocardiography is indicated for:

• All diastolic murmurs (virtually always pathological) 2, 1
• Systolic murmurs grade ≥3/6 2
• Any murmur with associated symptoms (dyspnea, syncope, chest pain) 2
• Holosystolic or late systolic murmurs at apex or left sternal edge 2
• Murmurs with abnormal physical findings (widely split S2, ejection sounds) 2

Echocardiography is NOT necessary for:

• Isolated soft (grade 1-2/6) midsystolic murmurs without symptoms or other abnormal findings 2, 3
• Cervical venous hum or mammary souffle (benign findings) 2

Effects of Pregnancy on Existing Murmurs

Pregnancy can alter the intensity of pre-existing murmurs:

• Stenotic lesions (mitral stenosis, aortic stenosis): Murmurs become louder due to increased blood volume and cardiac output 2, 1
• Regurgitant lesions (mitral regurgitation, aortic regurgitation): Murmurs may become softer or inaudible due to decreased systemic vascular resistance 2, 1

High-Risk Valvular Lesions in Pregnancy

Special attention should be given to these high-risk conditions:

1. Severe aortic stenosis (with or without symptoms)
2. Aortic regurgitation with NYHA class III-IV symptoms
3. Mitral stenosis with NYHA class II-IV symptoms
4. Mitral regurgitation with NYHA class III-IV symptoms
5. Valve disease with severe pulmonary hypertension
6. Valve disease with severe LV dysfunction (EF <0.40)
7. Mechanical prosthetic valves requiring anticoagulation
8. Marfan syndrome with or without aortic regurgitation 2

Management Approach

For Physiologic Murmurs:

• Reassurance and routine prenatal care
• No specific cardiac follow-up needed 1

For Pathologic Murmurs:

• Echocardiographic assessment
• Cardiology consultation
• Serial monitoring based on severity 1
• For high-risk lesions: consider specialized care at centers with expertise in managing cardiac disease in pregnancy 2

Common Pitfalls to Avoid

1. Over-investigation: Echocardiography is not necessary for all murmurs in pregnancy, particularly isolated soft systolic murmurs without other abnormal findings 3

2. Under-investigation: Diastolic murmurs are virtually always pathological and require evaluation regardless of symptoms 2, 4

3. Misinterpretation: Normal findings in pregnancy include physiologic S3, mild ventricular chamber enlargement, and physiologic valve regurgitation on Doppler imaging 1

4. Position-related symptoms: Remember that supine position can cause inferior vena caval compression by the gravid uterus, leading to hypotension - use left lateral positioning when evaluating pregnant women 1

By following this systematic approach to evaluating murmurs in pregnancy, clinicians can appropriately distinguish between benign physiologic findings and potentially serious cardiac conditions requiring intervention.