Types of murmurs
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heart murmurs systolic diastolic continuous classification auscultation Merck Manual
Heart murmurs are turbulent blood-flow sounds. They are classified mainly by timing in the cardiac cycle:
| Type | Timing | Common causes / examples |
|---|---|---|
| Systolic murmurs | Between S1 and S2 | Ejection systolic: aortic stenosis, pulmonary stenosis, hypertrophic cardiomyopathy, innocent flow murmur. Pansystolic (holosystolic): mitral regurgitation, tricuspid regurgitation, ventricular septal defect. Late systolic: mitral valve prolapse. |
| Diastolic murmurs | Between S2 and S1 | Early decrescendo: aortic regurgitation, pulmonary regurgitation. Mid-diastolic rumble: mitral stenosis, tricuspid stenosis. Presystolic accentuation may occur in mitral stenosis when sinus rhythm is present. |
| Continuous murmurs | Persist through systole and diastole, crossing S2 | Patent ductus arteriosus, arteriovenous fistula, ruptured sinus of Valsalva. The classic PDA murmur is “machinery-like.” |
Other useful descriptors:
- Site: aortic area, pulmonary area, tricuspid area, mitral apex.
- Radiation: aortic stenosis often radiates to carotids; mitral regurgitation to axilla.
- Shape: crescendo-decrescendo, plateau, decrescendo.
- Pitch/quality: harsh, blowing, rumbling, musical.
- Intensity: systolic murmurs are graded I/VI to VI/VI. Grade IV or more has a palpable thrill.
- Response to maneuvers: right-sided murmurs usually become louder with inspiration; most murmurs decrease on standing/Valsalva, whereas hypertrophic cardiomyopathy and mitral valve prolapse typically become louder.
High-yield rule: systolic murmurs may be innocent or pathological; diastolic and continuous murmurs should be considered pathological until evaluated. This is consistent with the Merck auscultation reference.
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