Heart Murmurs: Etiologies, Classification, and Clinical Significance

A heart murmur is an audible vibration from turbulent blood flow. Not all murmurs indicate disease.

Classification

• Timing: Systolic (most common), diastolic, continuous.
• Grade (Levine 1–6): Intensity. Grade ≥3 or diastolic/continuous = usually pathologic.
• Quality/Configuration: Crescendo-decrescendo (ejection), holosystolic (regurgitant), decrescendo (diastolic), machinery (continuous).
• Location/Radiation: Aortic (RUSB), Pulmonic (LUSB), Tricuspid (LLSB), Mitral (apex).

Common Causes

Category	Examples	Murmur Type
Valvular	Aortic stenosis, Mitral regurgitation, Mitral valve prolapse, Aortic regurgitation, Tricuspid regurgitation	Systolic ejection, Holosystolic, Late systolic, Diastolic decrescendo, Holosystolic
Congenital	VSD, ASD, PDA, PS, AS, Coarctation	Holosystolic (VSD), Fixed split S2 (ASD), Continuous machinery (PDA)
Functional/Innocent	Still's murmur (children), Pregnancy, Anemia, Hyperthyroidism, Fever, High output states	Soft, systolic ejection, grade 1–2, normal S2, no clicks
Other	HOCM (dynamic LVOTO), MVP, Pulmonary hypertension (Graham Steell), Aortic dissection	Variable

Evaluation

History, exam (dynamic maneuvers: Valsalva, squatting, handgrip), ECG, Echo (gold standard). Innocent murmurs need no restriction. Pathologic murmurs require etiology-specific management (surveillance, medication, intervention).