How should I evaluate and manage a patient who has a heart murmur discovered on physical examination?

Evaluation and Management of Heart Murmurs

Immediate Decision: Does This Murmur Require Echocardiography?

All diastolic murmurs, continuous murmurs, holosystolic murmurs, and late systolic murmurs require echocardiography—these are virtually always pathologic and demand immediate evaluation. 1, 2, 3

High-Risk Murmurs Requiring Urgent Echocardiography

Proceed directly to echocardiography if ANY of the following are present:

Murmur Characteristics:

• Any diastolic murmur (always pathologic) 1, 2
• Any continuous murmur (except venous hums and mammary souffles) 1, 2
• Holosystolic/pansystolic murmur 2, 3
• Late systolic murmur 2, 3
• Grade 3 or louder midsystolic murmur 2, 3
• Murmur with ejection clicks 2, 3
• Murmur radiating to neck or back 2, 3
• Any murmur difficult to characterize on examination 4

Associated Clinical Findings:

• Symptoms: syncope, angina, heart failure, dyspnea, thromboembolism 2, 3
• Fever with new murmur (suspect endocarditis) 1, 2, 3
• Abnormal cardiac findings: displaced/hyperdynamic apex, abnormal S2 (fixed splitting, soft/absent A2, reversed splitting), S3 gallop, pulmonary rales 1, 3
• Abnormal pulses: slow-rising diminished pulse (parvus et tardus), bounding pulses 1
• Abnormal ECG or chest X-ray findings 2

Systolic Murmurs: The Critical Distinction

For midsystolic murmurs in asymptomatic patients, use dynamic auscultation to differentiate innocent from pathologic:

Dynamic Maneuvers to Characterize Murmurs

Respiration:

• Right-sided murmurs increase with inspiration 1
• Left-sided murmurs louder during expiration 1

Valsalva Maneuver:

• Most murmurs decrease in intensity 1
• Hypertrophic cardiomyopathy becomes much louder (critical red flag) 1
• Mitral valve prolapse becomes longer and louder 1

Handgrip Exercise:

• Increases murmurs of mitral regurgitation, ventricular septal defect, and aortic regurgitation 1
• Increases flow murmurs across stenotic valves 1

Positional Changes (Standing):

• Innocent murmurs typically decrease or remain unchanged 2
• Hypertrophic cardiomyopathy murmur increases 1

When Systolic Murmurs Can Be Observed Without Echocardiography

Only if ALL of the following criteria are met:

• Grade 1-2 intensity 2
• Midsystolic timing (not holosystolic or late systolic) 2, 3
• Normal S2 intensity and splitting 2
• No ejection clicks 2
• No radiation to neck or back 2
• Asymptomatic patient 2, 3
• Normal cardiac examination otherwise 2
• Experienced examiner confident in identifying innocent murmur 4

Common pitfall: Do not assume a "quiet" systolic murmur is benign—even grade 2/6 holosystolic murmurs can represent severe chronic mitral regurgitation. 3 Difficulty characterizing the murmur is itself an indication for echocardiography. 4

Special Clinical Scenarios

Murmur with Anemia

• Anemia commonly causes functional systolic ejection murmurs (grade 1-2, left sternal border) due to increased cardiac output 2
• Still perform echocardiography to evaluate the murmur 2
• Treat underlying anemia with complete blood count, iron studies, and appropriate iron replacement 2
• Reassess murmur after anemia correction—functional murmurs should diminish or resolve 2
• Persistence after anemia treatment indicates structural heart disease 2

Suspected Infective Endocarditis

• Right heart murmur at lower left sternal border in injection drug user with fever, petechiae, Osler's nodes, and Janeway lesions suggests tricuspid regurgitation from endocarditis 1
• Requires immediate echocardiography 2, 3

Fixed Splitting of S2

• Grade 2/6 midsystolic murmur in pulmonic area with fixed splitting during inspiration and expiration suggests atrial septal defect 1
• Requires echocardiography 1

Role of Ancillary Testing

ECG and Chest X-ray:

• Not routinely needed for all murmurs 2, 5
• Can be obtained if immediately available but should not delay echocardiography 2, 3
• Abnormal findings (ventricular hypertrophy, chamber enlargement, pulmonary congestion) mandate echocardiography 2, 3

Echocardiography provides definitive assessment:

• Valve morphology and function 4, 2
• Chamber size and wall thickness 4, 2
• Ventricular function 4, 2
• Pulmonary artery pressures 4, 2

Cardiac catheterization:

• Not necessary for most patients with diagnostic echocardiograms 2
• Reserved for discrepancies between echocardiographic and clinical findings 2

Pediatric Considerations

In children, the same principles apply with additional considerations:

• Neonatal heart murmurs are more likely to represent structural heart disease and require echocardiography 6
• Family history of sudden cardiac death or congenital heart disease increases likelihood of pathology 6
• Red flags in children: holosystolic or diastolic murmur, grade 3 or higher, harsh quality, abnormal S2, maximal intensity at upper left sternal border, systolic click, increased intensity when standing 6
• Referral to pediatric cardiologist recommended when specific innocent murmur cannot be confidently identified 6, 7