What is the management approach for a soft systolic murmur over the left sternal edge (LSE) in pregnancy?

Management of Soft Systolic Murmur Over Left Sternal Edge in Pregnancy

A soft grade 1-2 midsystolic murmur at the left sternal edge is a normal physiologic finding in pregnancy and typically requires no further workup in an asymptomatic patient with an otherwise normal cardiac examination. 1, 2

Physiologic Basis

The hemodynamic changes of normal pregnancy create benign flow murmurs in most pregnant women:

• Increased blood volume (50% increase) and cardiac output produce turbulent flow across normal cardiac structures, generating soft systolic murmurs heard best at the mid to upper left sternal edge 1, 2
• These murmurs are typically grade 1-2/6 in intensity, midsystolic in timing, and represent physiologic flow rather than structural heart disease 1, 2
• Other normal cardiovascular findings in pregnancy include hyperkinetic precordial impulse, louder S1 with prominent splitting, physiologically split S2 (may appear fixed in late pregnancy), and S3 gallops present in most patients 1, 2

When Echocardiography is NOT Needed

Echocardiography is not necessary for asymptomatic patients with soft (grade 1-2) midsystolic murmurs and otherwise normal physical findings, particularly in younger patients 1

This approach is supported by research showing that echocardiography does not substantially alter management in pregnant patients with isolated soft systolic murmurs at the left sternal edge without other clinical abnormalities 3

When Echocardiography IS Indicated

Obtain echocardiography if ANY of the following features are present:

Murmur Characteristics Requiring Evaluation

• Any diastolic murmur (excluding cervical venous hum or mammary souffle) 1, 2
• Holosystolic or late systolic murmurs at the apex or left sternal edge 1
• Grade 3 or louder midsystolic murmurs 1
• Murmurs that increase with Valsalva maneuver or standing, or decrease with squatting (suggests hypertrophic cardiomyopathy or mitral valve prolapse) 1
• Murmurs that increase during transient arterial occlusion or sustained handgrip (suggests mitral regurgitation or ventricular septal defect) 1

Clinical Features Requiring Evaluation

• Symptoms: dyspnea beyond normal pregnancy, chest pain, syncope, palpitations, or signs of heart failure 1, 2
• Abnormal physical findings: widely split S2, systolic ejection clicks, abnormal carotid pulses, or evidence of ventricular dysfunction 1
• History of structural heart disease, previous rheumatic fever, congenital heart disease, or family history of cardiomyopathy 1
• NYHA class II or higher symptoms 1

Common Pitfall to Avoid

Do not confuse normal pregnancy findings with pathology:

• Continuous murmurs in pregnancy are usually benign (cervical venous hum or mammary souffle) and can be distinguished by specific maneuvers 1
• Cervical venous hum: heard in right supraclavicular fossa, obliterated by chin movement toward stethoscope or digital pressure on ipsilateral jugular vein 1
• Mammary souffle: heard over engorged breast, obliterated by firm stethoscope pressure, attenuates when standing 1

High-Risk Conditions Requiring Specialized Management

If echocardiography reveals significant pathology, the following conditions carry high maternal and/or fetal risk and require cardio-obstetrics team involvement 1:

• Severe aortic stenosis (with or without symptoms)
• Moderate-to-severe mitral stenosis with NYHA class II-IV symptoms
• Severe pulmonary hypertension (>75% of systemic pressures)
• Left ventricular dysfunction (ejection fraction <0.40)
• Mechanical prosthetic valves requiring anticoagulation
• Marfan syndrome

Follow-Up Strategy

For confirmed physiologic murmurs:

• No specific cardiac follow-up required beyond routine prenatal care 3
• Reassess if new symptoms develop 2

For identified structural disease:

• Follow-up frequency depends on severity: monthly to bimonthly for moderate-severe lesions 1
• Delivery planning should involve cardio-obstetrics team for significant valvular disease 1