Auscultogram from normal and abnormal heart sounds
Murmurs are extra heart sounds that are produced as a result of turbulent blood flow that is sufficient to produce audible noise. Most murmurs can only be heard with the assistance of a stethoscope ("on auscultation").
A functional murmur or "physiologic murmur" is a heart murmur that is primarily due to physiologic conditions outside the heart, as opposed to structural defects in the heart itself. Functional murmurs may be benign (an "innocent murmur"), mildly troublesome, or serious.
Murmurs may also be the result of various problems, such as narrowing or leaking of valves, or the presence of abnormal passages through which blood flows in or near the heart. Such murmurs, known as pathologic murmurs, should be evaluated by an expert.
Murmurs can be classified by seven different characteristics: timing, shape, location, radiation, intensity, pitch and quality.
- Timing refers to whether the murmur is a systolic or diastolic murmur.
- Shape refers to the intensity over time; murmurs can be crescendo, decrescendo or crescendo-decrescendo.
- Location refers to where the heart murmur is usually auscultated best. There are six places on the anterior chest to listen for heart murmurs; each of the locations roughly corresponds to a specific part of the heart. The first five of the six locations are adjacent to the sternum. The six locations are:
- the 2nd right intercostal space
- the 2nd to 5th left intercostal spaces
- the 5th mid-clavicular intercostal space.
- Radiation refers to where the sound of the murmur radiates. The general rule of thumb is that the sound radiates in the direction of the blood flow.
- Intensity refers to the loudness of the murmur, and is graded on a scale from 0-6/6.
- Pitch can be low, medium or high and is determined by whether it can be auscultated best with the bell or diaphragm of a stethoscope.
- Quality refers to unusual characteristics of a murmur, such as blowing, harsh, rumbling or musical.
Grading of murmurs
|Grading of Murmurs|
|Grade 1||Very faint|
|Grade 3||Heard all over the precordium|
|Grade 4||Loud, with palpable thrill (i.e. a tremor or vibration felt on palpation)|
|Grade 5||Very loud, with thrill. May be heard when stethoscope is partly off the chest.|
|Grade 6||Very loud, with thrill. May be heard with stethoscope entirely off the chest.|
Interventions that change murmur sounds
- Inhalation will increase the amount of blood filling into the right ventricle, thereby prolonging ejection time. This will affect the closure of the pulmonary valve. This finding, also called Carvallo's Maneuver,has been found by studies to have a sensitivity of 100% and a specificity of 80% to 88% in detecting murmurs originating in the right heart.
- abrupt standing
- valsalva maneuver. One study found the valsalva maneuver to have a sensitivity of 65%, specificity of 96% in detecting Hypertrophic obstructive cardiomyopathy (HOCM).
- hand grip
- post ectopic potentiation
- amyl nitrite
- positioning of the patient. ie. positioning patients in the left lateral position will allow a murmur in the mitral valve area to be more pronounced.
Examples of anatomic source of murmur
- Stenosis of Bicuspid aortic valve
- Symptoms tend to present between 40 and 70 years of age.
- Stenosis of Tricuspid Aortic Valve
- Symptoms more likely to present after 80 years of age.
- Hypertrophic subaortic stenosis
- Symptoms are a harsh murmur in mid-systole, often accompanied by S4, Brisk Bifid Carotid upstroke. Murmur increases with standing and valsalva maneuver.
- Ventral septal defect
- Symptoms are holosystolic, heard best at left lower sternal border.
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- Information on heart murmurs in children from Seattle Children's Heart Center
- Heart Murmurs in Pediatric Patients
- The Auscultation Assistant Provides recordings of heart murmurs.
- Easy Auscultation Provides a library of sounds, text, waveforms and animations for over 50 murmurs and abnormalities.
- heart murmur at Dorland's Medical Dictionary
- continuous murmur at Dorland's Medical Dictionary
- "Murmur: characteristics". LifeHugger. Retrieved 2009-09-23.
- "Medline Plus Medical Dictionary, definition of "cardiac thrill"".
- Lembo N, Dell'Italia L, Crawford M, O'Rourke R (1988). "Bedside diagnosis of systolic murmurs". N Engl J Med. 318 (24): 1572–8. doi:10.1056/NEJM198806163182404. PMID 2897627.
- Maisel A, Atwood J, Goldberger A (1984). "Hepatojugular reflux: useful in the bedside diagnosis of tricuspid regurgitation". Ann Intern Med. 101 (6): 781–2. PMID 6497192.