Cardiac Murmurs and Auscultation
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Direct answer
Cardiac murmurs are audible turbulence produced by blood flow through stenotic, regurgitant or shunting lesions, and they are described by timing, location, radiation, grade and response to manoeuvres. Levine grading runs from I to VI, with grade VI audible even with the stethoscope lifted from the chest, and a thrill usually accompanies grade IV and above. Systolic murmurs are classed as ejection, pansystolic or late systolic, while diastolic murmurs are classed as early, mid or late.
What you must remember
- Timing: a systolic murmur sits between S1 and S2, a diastolic murmur between S2 and the next S1, and a continuous murmur spans both, as in PDA.
- Ejection systolic: crescendo-decrescendo, typical of aortic and pulmonary stenosis, and of physiological flow murmurs in anaemia, fever or pregnancy.
- Pansystolic: a plateau murmur from mitral regurgitation, tricuspid regurgitation or VSD, starting with S1 and running to S2.
- Late systolic: a mid-to-late systolic murmur of mitral valve prolapse, preceded by a click.
- Early diastolic: a high-pitched decrescendo murmur of aortic regurgitation, best heard sitting forward; the Graham Steell murmur is the pulmonary equivalent.
- Mid-diastolic: the rumble of mitral stenosis with an opening snap, and the Austin Flint murmur of aortic regurgitation.
- Pericardial friction rub: a scratchy sound with up to three components per cycle, changing with posture and breath-holding.
- Manoeuvres: Valsalva and standing increase hypertrophic and prolapse murmurs; squatting and handgrip increase regurgitant and VSD murmurs.
Working through a systolic murmur at the bedside
A 60-year-old man with exertional breathlessness has a harsh crescendo-decrescendo systolic murmur in the aortic area that radiates to the carotids, a slow-rising pulse and a soft second sound.
- Timing and shape: An ejection systolic murmur narrows the differential to flow across the outflow tract or a stenotic valve.
- Location and radiation: The aortic area with carotid radiation points to aortic stenosis rather than hypertrophic cardiomyopathy, which is best heard at the lower left edge.
- The pulse: A slow-rising, small pulse supports severe stenosis, whereas in hypertrophic obstruction the pulse is brisk and bisferiens.
- Manoeuvres: Valsalva reduces the aortic murmur but increases the hypertrophic one.
- Second sound: A soft or single S2 suggests severe disease.
- Investigate: Echocardiography quantifies valve area and gradient, and the decision for valve replacement depends on symptoms, gradient and ventricular function.
A flow murmur from anaemia would differ, with a soft ejection murmur, a normal pulse and a normal second sound.
Where the examiner's murmurs sound alike
Many murmurs sound similar at the bedside, and the examiner tests how the candidate uses timing and manoeuvres to separate them.
- Trap: confusing aortic stenosis with hypertrophic cardiomyopathy Correct: both are ejection systolic murmurs, but aortic stenosis is heard at the right upper sternal border with carotid radiation and HCM at the lower left sternal edge, and Valsalva and the pulse separate them further.
- Trap: mixing up mitral regurgitation and VSD Correct: both are pansystolic, but the VSD murmur is at the lower left sternal edge with a thrill, while the mitral regurgitation murmur radiates to the axilla.
- Trap: mistaking the Austin Flint murmur for mitral stenosis Correct: an opening snap and a loud first sound point to mitral disease, whereas the Austin Flint murmur is a mid-diastolic rumble of aortic regurgitation.
- Trap: calling every ejection murmur pathological Correct: the physiological flow murmur of anaemia, fever or pregnancy is soft, with a normal pulse and second sound.
Frequently asked questions
What does Levine grading of murmurs mean?
Levine grading ranks murmur intensity from grade I, barely audible, to grade VI, audible with the stethoscope lifted off the chest. A thrill is usually present at grade IV and above.
Which manoeuvres change the murmur of hypertrophic cardiomyopathy?
The murmur of hypertrophic cardiomyopathy increases with standing and Valsalva, and decreases with squatting and handgrip. These manoeuvres help separate it from aortic stenosis, where Valsalva reduces the murmur.
How does an Austin Flint murmur differ from mitral stenosis?
The Austin Flint murmur is a low-pitched mid-diastolic rumble of aortic regurgitation. It lacks the opening snap and loud first sound that accompany the rumble of mitral stenosis.
What is a pericardial friction rub?
A pericardial friction rub is a scratchy, superficial sound with up to three components per cycle. It changes with posture and breathing, and it signals pericardial inflammation.
What does a soft ejection systolic murmur with a normal pulse suggest?
A soft ejection systolic flow murmur with a normal pulse and normal second sound suggests a physiological cause such as anaemia, fever or pregnancy. Structural disease is less likely when these features are present.