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[Physiology](https://durgical.com/en/physiology/) · [Cardiovascular](https://durgical.com/en/physiology/#s-cardio)

# Murmurs and the hemodynamics of valve disease

- Mechanism
- Exam priority: medium

A murmur is the sound of blood flowing turbulently through a narrow valve, a valve that does not close, or an abnormal opening.

Updated 2026-11-01

**See it in 3D:** [Mitral anterior leaflet](https://durgical.com/en/anatomy/anterior-leaflet-of-left-atrioventricular-valve/) · [Aortic non-coronary cusp](https://durgical.com/en/anatomy/non-coronary-leaflet-of-aortic-valve/) · [Chordae tendineae](https://durgical.com/en/anatomy/chordae-tendineae-of-right-atrioventricular-valve/) · [Interventricular septum](https://durgical.com/en/anatomy/interventricular-septum/) · [Left ventricle](https://durgical.com/en/anatomy/left-ventricle/)

## Key points

- Systolic: aortic stenosis (ejection, crescendo–decrescendo, radiates to the carotids), mitral regurgitation (holosystolic, radiates to the axilla) and VSD (holosystolic at the lower left sternal border).
- Diastolic: aortic regurgitation (early decrescendo, left sternal border) and mitral stenosis (opening snap and rumble).
- Raising afterload (handgrip, squatting) makes mitral regurgitation, aortic regurgitation and VSD louder.
- Lowering preload (Valsalva, standing) softens most murmurs, except hypertrophic obstructive cardiomyopathy and mitral prolapse (the click comes earlier).
- In Colombia rheumatic heart disease is still the leading cause of mitral stenosis in young adults.

## What it is

Blood flows silently while flow stays laminar. When it races through a narrow opening or leaks back through an incompetent valve, it turns turbulent and vibrates: that is the murmur. When in the cycle it sounds tells you which valve fails and whether it is stenosis or regurgitation.

## How it works, step by step

- Flow turns turbulent when the Reynolds number rises: high velocity, a narrow orifice, thin blood (anemia).
- Turbulence vibrates the walls and the chest; the stethoscope hears it as a murmur.
- Stenosis: the chamber needs more pressure to force blood through; a pressure gradient appears across the valve.
- Regurgitation: part of the volume goes back to the chamber it came from and adds to the next filling (volume overload).
- Pressure overload causes concentric hypertrophy; volume overload causes dilation with eccentric hypertrophy.
- Over time left atrial pressure rises, the lungs congest and atrial fibrillation may appear.

### Cardiac cycle (Wiggers diagram)

**HR** 75/min **Cycle** 800 ms **Systole** ≈ 300 ms **SV** 70 mL **EF** 58%

Tap a number (phase), a dot (valve) or a sound.

1 Atrial systole · 2 Isovolumetric contraction · 3 Rapid ejection · 4 Reduced ejection · 5 Isovolumetric relaxation · 6 Rapid filling · 7 Diastasis (slow filling).

MC mitral closure · AO aortic opening · AC aortic closure · MO mitral opening.

- Aorta
- Left ventricle (LV)
- Left atrium (LA)
- LV volume
- ECG
- S1 and S2
- Ventricular systole
- Ventricular diastole
- Valve events (MC, AO, AC, MO)

Find S1 and S2: anything between them is systolic; after S2, diastolic.

### Left-ventricular pressure–volume loop

**EDV** 115 mL **ESV** 51 mL **SV** 64 mL **EF** 56% **ESP** 206 mmHg **LV peak** ≈ 222 mmHg

#### Aortic stenosis

Aortic stenosis: the LV must build a very high systolic pressure to push through the narrow valve (the aorta sees much less); the loop is tall, SV tends to fall and concentric hypertrophy stiffens filling.

Tap a corner of the loop (MC, AO, AC, MO) to see the valve event.

- Current loop
- Normal loop
- ESPVR (contractility, Ees)
- EDPVR (passive filling)
- Ea (arterial afterload)
- Stroke volume (SV)

Compare aortic stenosis with the mitral and aortic regurgitation presets.

## Classic murmurs (where and why)

| Lesion | Timing | Best heard | Key hemodynamics |
| --- | --- | --- | --- |
| [Aortic stenosis](https://durgical.com/en/conditions/aortic-valve-stenosis/) | Midsystolic ejection | 2nd right intercostal space, radiates to carotids | LV–aorta gradient; weak, late pulse; concentric hypertrophy |
| [Aortic regurgitation](https://durgical.com/en/conditions/aortic-regurgitation/) | Early diastolic decrescendo | Left sternal border | Wide pulse pressure; large stroke volume; LV dilation |
| [Mitral regurgitation](https://durgical.com/en/conditions/mitral-regurgitation/) | Holosystolic | Apex, radiates to axilla | No true isovolumetric phase; large left atrium |
| [Mitral stenosis](https://durgical.com/en/conditions/rheumatic-heart-disease/) | Opening snap and diastolic rumble | Apex, left lateral decubitus | LA–LV gradient; large atrium; pulmonary congestion |
| [Ventricular septal defect](https://durgical.com/en/conditions/ventricular-septal-defect/) | Holosystolic | Lower left sternal border | Left-to-right shunt; small defects sound louder |

## Clinical notes

- A diastolic murmur is always pathological; a soft systolic one in a healthy child or a pregnant woman may be a high-flow functional murmur.
- In aortic stenosis the triad of angina, syncope and dyspnea marks severe disease.
- Rheumatic fever after streptococcal pharyngitis damages the mitral valve most of all.

## Memory aid

"Opens badly, stenosis; closes badly, regurgitation": the first sounds when the valve should be open, the second when it should be shut.

## Test yourself

Think of the answer, then tap the question to see it.

## Why does aortic stenosis cause a systolic murmur and aortic regurgitation a diastolic one?

The aortic valve should be open in systole (stenosis obstructs forward flow) and closed in diastole (regurgitation lets blood fall back from the aorta into the ventricle).

## What happens to a mitral regurgitation murmur when the patient squeezes both hands hard?

It gets louder: handgrip raises afterload, so blood finds it easier to go back into the left atrium than out into the aorta.

## Why does chronic aortic regurgitation widen the pulse pressure?

The ventricle ejects a large volume (high systolic) and blood runs back in diastole (low diastolic).

## Why can a small VSD be louder than a large one?

A small hole keeps a high pressure gradient between the ventricles and a fast, turbulent jet; in a large defect the pressures equalize and the jet slows.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/physiology/murmurs-and-the-hemodynamics-of-valve-disease/)

## See it in 3D

The structures of Durgical's 3D anatomy where it happens.

- [Mitral anterior leaflet](https://durgical.com/en/anatomy/anterior-leaflet-of-left-atrioventricular-valve/)
- [Aortic non-coronary cusp](https://durgical.com/en/anatomy/non-coronary-leaflet-of-aortic-valve/)
- [Chordae tendineae](https://durgical.com/en/anatomy/chordae-tendineae-of-right-atrioventricular-valve/)
- [Interventricular septum](https://durgical.com/en/anatomy/interventricular-septum/)
- [Left ventricle](https://durgical.com/en/anatomy/left-ventricle/)

## Related topics

- [Heart sounds and where they come from](https://durgical.com/en/physiology/heart-sounds-and-where-they-come-from/)
- [The cardiac cycle](https://durgical.com/en/physiology/the-cardiac-cycle/)
- [The ventricular pressure–volume loop](https://durgical.com/en/physiology/the-ventricular-pressure-volume-loop/)
- [Flow, pressure and resistance: Poiseuille and turbulent flow](https://durgical.com/en/physiology/flow-pressure-and-resistance-poiseuille-and-turbulent-flow/)
- [Physiology of congenital shunts](https://durgical.com/en/physiology/physiology-of-congenital-shunts/)

## Related conditions

- [Aortic Valve Stenosis](https://durgical.com/en/conditions/aortic-valve-stenosis/)
- [Aortic regurgitation](https://durgical.com/en/conditions/aortic-regurgitation/)
- [Mitral regurgitation](https://durgical.com/en/conditions/mitral-regurgitation/)
- [Rheumatic heart disease](https://durgical.com/en/conditions/rheumatic-heart-disease/)
- [Ventricular septal defect](https://durgical.com/en/conditions/ventricular-septal-defect/)
- [Infective endocarditis](https://durgical.com/en/conditions/infective-endocarditis/)

[← All of physiology](https://durgical.com/en/physiology/)

Educational physiology content; not a diagnostic or treatment guide and no substitute for a health professional's advice. Values are approximate references. No doses are given.

Sources: [19.3 Cardiac Cycle](https://openstax.org/books/anatomy-and-physiology-2e/pages/19-3-cardiac-cycle) (OpenStax (Rice University), 2022); [Aortic Stenosis](https://www.ncbi.nlm.nih.gov/books/NBK557628/) (StatPearls (NCBI Bookshelf), 2024); [Mitral Regurgitation](https://www.ncbi.nlm.nih.gov/books/NBK553135/) (StatPearls (NCBI Bookshelf), 2026); [Rheumatic Heart Disease](https://www.ncbi.nlm.nih.gov/books/NBK538286/) (StatPearls (NCBI Bookshelf), 2023); Hall JE. Guyton and Hall Textbook of Medical Physiology, 13th ed. (ch. 23). Reference book used to check facts; its text and figures are not reproduced (Elsevier, 2016).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/physiology/murmurs-and-the-hemodynamics-of-valve-disease/