Heart Murmurs

How to Cite This Chapter: Ibrahim O, Sibbald M, Szczeklik W, Leśniak W. Heart Murmurs. McMaster Textbook of Internal Medicine. Kraków: Medycyna Praktyczna. https://empendium.com/mcmtextbook/chapter/B31.I.1.107.2. Accessed May 29, 2023.
Last Updated: December 14, 2020
Last Reviewed: April 10, 2021
Chapter Information

A heart murmur occurs when laminar blood flow becomes turbulent due to:

1) Increased flow through a normal valve or vessel (in patients with hyperdynamic circulation).

2) Flow through a stenotic valve or inflow of blood into a dilated vessel (eg, in aortic aneurysms).

3) Backflow caused by valvular regurgitation.

4) Passage through an abnormal communication (eg, in ventricular septal defects).

On examination, establish the following characteristics of the murmur: area where it is the loudest (areas of auscultation: see Figure 1.15-1), systolic versus diastolic, intensity, radiation, character, and factors increasing and decreasing the loudness (dynamic auscultation). Right-sided murmurs become louder with inspiration.

The intensity of a heart murmur is graded on the Levine scale of 1 to 6:

1) Grade 1 murmur: The softest of audible murmurs; it can only be heard with significant attention.

2) Grade 2 murmur: Soft but audible immediately on placing the stethoscope on the chest.

3) Grade 3 murmur: Intermediate intensity, easily audible, similar to that of breath sounds.

4) Grade 4 murmur: Loud and accompanied by a palpable thrill.

5) Grade 5 murmur: Similar to the grade 4 murmur but loud enough to be heard with only the edge of the stethoscope touching the chest.

6) Grade 6 murmur: Audible with the stethoscope off the chest.

Note that hemodynamic changes associated with murmurs are complex, and valvular lesions may present atypically in unique circumstances and when combined with other cardiovascular abnormalities. Classic features of common murmurs: Table 1.15-1.


Table 1.15-1. Features of the most frequent cardiac murmurs


Loudest location and radiation


Dynamic auscultation maneuvers


Systolic murmurs


Right upper sternal border; AS radiating to carotids or clavicles is more severe

Crescendo-decrescendo (ejection)

Increases with release phase of Valsalvaa and squatting, decreases with strain phase of Valsalva and standing

Syncope, angina; pulsus parvus et tardus; brachioradial and carotid-apical delay; later-peaking AS and AS with absent A2 or reverse splitting S2 are more severe

Hypertrophic obstructive cardiomyopathy

Left sternal border

Crescendo-decrescendo (ejection)

Increases with strain phase of Valsalva and standing, decreases with release phase of Valsalva and squatting

Family history of sudden cardiac death or syncope; arrhythmia; MR

Physiologic “flow” murmurs

Can vary depending on underlying cause, generally upper sternal border (aortic and pulmonic outflow tracts); unlike severe AS, these do not radiate

Crescendo-decrescendo (ejection)

Often diminish with standing and Valsalva strain phase

High output states (eg, anemia, fever, pregnancy, thyrotoxicosis); ASD can cause flow murmur due to increased output through pulmonic valve


Apex radiating to axilla, but sternal and posterior radiation possible depending on affected leaflet

Typically pansystolic, although may be early, mid-, or late systolic depending on cause and chronicity

May be increased by handgrip or squatting and decreased by standing

Findings of LV volume overload if chronic (S3 and laterally displaced, sustained, high-amplitude apical impulse)

Mitral valve prolapse

Apex with variable radiation depending on affected leaflet

Midsystolic ejection click followed by “pansystolic”-type murmur

Decreased by handgrip and squatting, increased by Valsalva strain phase and standing; click/murmur occurs later with preload increases, earlier with decreased preload

Elevated risk of sudden cardiac death, infective endocarditis, potentially stroke/TIA and arrhythmia

Tricuspid regurgitation

Lower left sternal border

Pansystolic, although may vary due to cause and chronicity

Increases with inspiration

Large c-v waves in jugular veins, pulsatile liver, ascites, peripheral edema, features of pulmonary hypertension (loud P2, RV heave). Can be caused by pacemaker in RV

Ventricular septal defect

Left sternal border with variable radiation


May be augmented by handgrip

May have palpable thrill or RV heave from left-right shunt

Diastolic murmurs

Mitral stenosis

Over apex, heard best in left lateral decubitus position

Opening snap followed by rumbling diastolic murmur

Augmented by exercise

History of rheumatic heart disease, features of PH, atrial fibrillation

Aortic regurgitation

Over left sternal border with patient leaning forward holding end-expiration

Early diastolic “blowing” decrescendo murmur; late diastolic murmur called a “flint murmur” may be also present

Augmented by handgrip

Connective tissue disorders, bicuspid valve aortopathy; peripheral signs include wide pulse pressure, Corrigan pulse,b Duroziez sign,c Traube sign,d Hill sign,e Austin Flint murmurf

a The Valsalva maneuver is performed by forcible exhalation against a closed glottis. The strain phase of the maneuver is the time of maximum expiration; this is a preload-reducing maneuver. The majority of heart murmurs become softer at this point, with the exception of those caused by hypertrophic cardiomyopathy with left ventricular outflow tract obstruction and mitral valve prolapse.

b Corrigan pulse (water-hammer pulse) refers to a rapidly rising and falling pulse. It is often seen at the carotid but can be accentuated at the brachial or radial pulse by raising the arm.

c Duroziez sign refers to a systolic and diastolic murmur heard over the femoral artery when it is compressed.

d Traube sign (pistol shot) refers to loud systolic and diastolic sounds when auscultating the femoral artery.

e Hill sign refers to a popliteal systolic blood pressure >20 mm Hg higher than the brachial.

f The Austin Flint murmur is a low-pitched diastolic murmur occurring in mid-late diastole from functional mitral valve obstruction related to the aortic regurgitation jet directed towards the mitral leaflets.

AS, aortic stenosis; ASD, atrial septal defect; LV, left ventricle; MR, mitral regurgitation; PH, pulmonary hypertension; RV, right ventricle; TIA, transient ischemic attack.

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