Heart murmurs and dynamic manoeuvres, from preload and afterload
A murmur follows the flow: manoeuvres that change preload or afterload change how much blood crosses the lesion. Hypertrophic obstructive cardiomyopathy is the exception that flips the rule.
Chapters (9)
Predict how Valsalva, squatting, handgrip, leg raise and inspiration change the intensity of common murmurs by altering preload and afterload.
The short version
- Every bedside manoeuvre changes preload, afterload or both, and a murmur follows the flow across the lesion: more blood, louder; less blood, softer.
- Preload falls with the strain phase of Valsalva and with standing up, and rises with squatting and passive leg raise; sustained handgrip raises afterload; inspiration increases venous return to the right heart.
- Valsalva and standing soften aortic stenosis, mitral regurgitation and ventricular septal defect; squatting makes aortic stenosis louder.
- Handgrip makes mitral regurgitation and ventricular septal defect louder and barely changes aortic stenosis; inspiration makes right-sided murmurs louder.
- Hypertrophic obstructive cardiomyopathy is the exception: a smaller ventricle worsens the obstruction, so Valsalva and standing make it louder, and squatting, leg raise and handgrip make it softer.
Heart murmurs and dynamic manoeuvres: same heart, same valve
A 58-year-old woman has a loud murmur at the apex. She is asked to squeeze a rubber ball for 30 seconds, and the murmur gets louder. Then she bears down, and it fades. The heart and the valve are the same throughout, so what changed?
The answer is the loading conditions. Dynamic manoeuvres change preload and afterload in a controlled way at the bedside, and the murmur responds. This lesson shows how to predict that response using only those two ideas.[1][3]
Preload, afterload and the four groups of manoeuvres
A murmur is the sound of turbulent flow across a valve or defect. Preload is how full the ventricle is before it contracts, and afterload is the pressure it pushes against. Both come from the pressure–volume loop lessons.
Every manoeuvre moves one or both. They fall into four groups:
| Group | Manoeuvre | Why |
|---|---|---|
| Preload down | Strain phase of Valsalva | High chest pressure squeezes venous return |
| Preload down | Standing up (from squatting) | Blood pools in the legs |
| Preload up | Squatting; passive leg raise | Leg blood is sent back to the heart |
| Afterload up | Sustained handgrip | Arterial pressure rises |
| Right-heart filling up | Inspiration | Breathing in pulls more blood into the right heart |
These effects on preload and afterload are the same in all three sources.[1][2][3]
The default rule: a murmur follows the flow
More blood across the lesion makes the murmur louder; less blood makes it softer. Applying that rule to each manoeuvre:
- Valsalva and standing: preload falls, so less blood crosses the valve. Aortic stenosis, mitral regurgitation and ventricular septal defect all get softer.[2][3]
- Squatting: more blood returns, so the aortic stenosis murmur gets louder.[3][4]
- Handgrip: this one changes afterload. Higher resistance to forward flow pushes more blood backward through a leaking mitral valve, or through a hole in the septum, so the murmurs of mitral regurgitation and ventricular septal defect get louder. Aortic stenosis barely changes, which is why handgrip separates it from mitral regurgitation.[1][2][3]
- Inspiration: breathing in pulls more blood into the right heart. Right-sided murmurs, such as tricuspid regurgitation, get louder; left-sided murmurs do not change much.[2][6]
| Lesion | Valsalva / standing | Squatting | Handgrip | Inspiration |
|---|---|---|---|---|
| Aortic stenosis | Softer | Louder | Little change | Little change |
| Mitral regurgitation | Softer | Louder | Little change | |
| Ventricular septal defect | Softer | Louder | ||
| Tricuspid regurgitation | Louder | |||
| Hypertrophic obstructive cardiomyopathy | Louder | Softer | Softer |
The twist: hypertrophic obstructive cardiomyopathy and prolapse
In hypertrophic obstructive cardiomyopathy (HOCM), the murmur comes from obstruction in the outflow of the left ventricle. A smaller, emptier ventricle makes that obstruction worse.[4][5]
So the rule flips. Valsalva and standing make the murmur louder, while squatting, leg raise and handgrip make it softer.[1][3][5]
Mitral valve prolapse follows the same logic. A smaller ventricle moves the click earlier in systole, and the murmur gets longer.[1][2]
Worked example: predicting one manoeuvre
A 64-year-old man has a harsh systolic murmur at the right upper sternal border, from aortic stenosis. He stands up from a squat. What happens to the murmur?
- Standing up from squatting: preload falls.
- Less blood returns, so less flow crosses the aortic valve.
- The murmur follows the flow: it gets softer.
Practice question
Original · USMLE styleA 22-year-old man is evaluated for light-headedness during basketball practice. He has no chest pain or syncope. Blood pressure is 122/76 mm Hg and heart rate is 70/min. Cardiac examination shows a harsh systolic murmur at the left lower sternal border. The murmur becomes louder during the strain phase of the Valsalva manoeuvre and softer when he squats. The intensity does not change with inspiration.
Common questions
How do dynamic manoeuvres change heart murmurs?
They change preload or afterload, which changes how much blood crosses the lesion. Most murmurs follow the flow: more blood makes them louder, less blood makes them softer.
What does handgrip do to a murmur?
Sustained handgrip raises afterload. It makes the murmurs of mitral regurgitation and ventricular septal defect louder and barely changes aortic stenosis, so it helps tell aortic stenosis from mitral regurgitation.
Why does inspiration make some murmurs louder?
Breathing in pulls more blood into the right heart, so right-sided murmurs such as tricuspid regurgitation get louder. Left-sided murmurs do not change much.
Why is hypertrophic obstructive cardiomyopathy different from other murmurs?
Its murmur comes from outflow obstruction, and a smaller, emptier ventricle makes the obstruction worse. It therefore gets louder with Valsalva and standing, and softer with squatting, leg raise and handgrip.
Transcript
Read the full narration, by chapter644 words
0:00Same heart, same valve: what changed the murmur?
A 58-year-old woman has a loud murmur at the apex. The doctor asks her to squeeze a rubber ball for 30 seconds, and the murmur gets louder. Then she bears down, and it fades. Same heart, same valve. So what changed? Today: predict how Valsalva, standing, squatting, leg raise, handgrip and inspiration change a murmur, using only preload and afterload.
0:27Preload and afterload in one minute
Last time we timed the heart sounds. A murmur is the sound of turbulent flow across a valve or defect. From the pressure-volume loops: preload is how full the ventricle is before it contracts, and afterload is the pressure it pushes against. Every bedside manoeuvre moves one or both.
0:46Four groups of manoeuvres
Four groups. Preload down: the strain phase of Valsalva, because high chest pressure squeezes venous return, and standing up, because blood pools in the legs. Preload up: squatting and passive leg raise, which send leg blood back to the heart. Afterload up: sustained handgrip, which raises arterial pressure. And inspiration, which pulls blood into the right heart. The default rule: a murmur follows the flow. More blood across the lesion, louder. Less blood, softer.
1:22Applying the rule: Valsalva, squatting, handgrip, inspiration
Let's apply it. Valsalva and standing first. Preload falls, so less blood crosses the valve. Aortic stenosis, mitral regurgitation and ventricular septal defect all get softer. Now squatting. More blood returns, so the aortic stenosis murmur gets louder. Handgrip is different, because it changes afterload. Higher resistance to forward flow pushes more blood backward through a leaking mitral valve, or through a hole in the septum. So the murmurs of mitral regurgitation and ventricular septal defect get louder. Aortic stenosis barely changes, which is why handgrip separates it from mitral regurgitation. Last, inspiration. Breathing in pulls more blood into the right heart. Right-sided murmurs, like tricuspid regurgitation, get louder. Left-sided murmurs do not change much.
2:19The twist: hypertrophic obstructive cardiomyopathy and prolapse
Now the twist. In hypertrophic obstructive cardiomyopathy, the murmur comes from obstruction in the outflow of the left ventricle. A smaller, emptier ventricle makes that obstruction worse. So the rule flips: Valsalva and standing make it louder, while squatting, leg raise and handgrip make it softer. Mitral valve prolapse follows the same logic. A smaller ventricle moves the click earlier in systole, and the murmur gets longer. Remember: most murmurs fall when preload falls. Hypertrophic cardiomyopathy gets louder, and prolapse gets longer.
2:58Worked example
Let's predict one. A 64-year-old man has a harsh systolic murmur at the right upper sternal border. He stands up from a squat. Preload falls, flow across the aortic valve falls, and the murmur gets softer. One rule, applied to the lesion.
3:15Practice question
Your turn. A 22-year-old man has light-headedness during basketball practice. Blood pressure is 122 over 76, and heart rate is 70. There is a harsh systolic murmur at the left lower sternal border. It gets louder in the strain phase of Valsalva and softer when he squats. It does not change with inspiration. Which murmur is most likely? A, aortic stenosis. B, mitral regurgitation. C, ventricular septal defect. D, hypertrophic obstructive cardiomyopathy. E, tricuspid regurgitation. Pause here and decide.
3:59Why each option is right or wrong
A is out: aortic stenosis gets softer with Valsalva, because less blood crosses the valve, and louder with squatting. B is out: mitral regurgitation also gets softer when preload falls. C is out: a ventricular septal defect gets softer with Valsalva, and louder with handgrip. E is out: tricuspid regurgitation is right-sided, so it would get louder with inspiration. So the answer is D: less filling makes the obstruction worse, so the murmur gets louder with Valsalva and softer with squatting.
4:37Recap and next lesson
Three things to keep. One: preload down, from Valsalva or standing, softens most murmurs. Preload up, from squatting, makes aortic stenosis louder. Two: handgrip raises afterload and makes mitral regurgitation and ventricular septal defect louder. Inspiration makes right-sided murmurs louder. Three: hypertrophic cardiomyopathy is the exception, louder when the ventricle is small. Next up: hypertrophic cardiomyopathy against aortic stenosis at the bedside.
Sources
Numbers in the text, e.g. [1], point here- Healio, Learn the Heart: Dynamic Auscultation. healio.com/cardiology/learn-the-heart/cardiology-review/topic-reviews/dynamic-auscultation
- Eko Health: Dynamic Auscultation Maneuvers. ekohealth.com/blogs/education/dynamic-auscultation-maneuvers
- StatPearls: Physiology, Cardiovascular Murmurs (NBK525958). ncbi.nlm.nih.gov/sites/books/NBK525958/
- medschool.co: Dynamic Manoeuvres. medschool.co/exam/cardio/dynamic-manoeuvres
- Hypertrophic cardiomyopathy review, PMC7154317. pmc.ncbi.nlm.nih.gov/articles/PMC7154317
- Rivero-Carvallo sign, historical article, PMC6652362. pmc.ncbi.nlm.nih.gov/articles/PMC6652362
The practice question is original and its patient is synthetic. Every fact is checked against the sources above in independent accuracy reviews. Always follow your local guidelines and your own laboratory’s ranges.
Image credits. All diagrams, charts and handwriting are drawn in code (original). No AI-generated anatomy. Thumbnail plate: Servier Medical Art (smart.servier.com), "Heart (sagittal overview)", licensed under CC BY 4.0, recoloured and resized. Previous: EP 01 · Heart Sounds: S1 to S4 and Splitting · Next: EP 03 · HOCM vs Aortic Stenosis at the Bedside
Corrections. None so far. Spotted an error? Email info@medservatory.com with the lesson code MS-S1-CARD-011.
For exam study only, not medical advice. Read the medical disclaimer.
In this series
Playlist on YouTube- EP 01S2 splitting and heart sounds S1–S4, explained5:26
- EP 02Heart murmurs and dynamic manoeuvres, from preload and afterload5:15
- EP 03HOCM vs aortic stenosis murmur: telling them apart at the bedside5:31
- EP 04Ventricular action potential: phases 0 to 4 and their ion currents5:15
- EP 05SA node pacemaker potential: phase 4 sets the heart rate5:17
- EP 06ECG waves and intervals: what P, PR, QRS, ST and QT mean5:29