Heart murmur
From Wikipedia, the free encyclopedia
| ICD-10 | R01. |
|---|---|
| ICD-9 | 785.2-785.3 |
| DiseasesDB | 29151 |
| MedlinePlus | 003266 |
| MeSH | D006337 |
Murmurs are abnormal heart sounds[1] that are produced as a result of turbulent blood flow which is sufficient to produce audible noise. This most commonly results from narrowing or leaking of valves or the presence of abnormal passages through which blood flows in or near the heart. Murmurs are not usually part of the normal cardiac physiology and thus warrant further investigations. However, they sometimes result from harmless flow characteristics of no clinical significance.
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[edit] Classification
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 auscultated best. There are 6 places on the anterior chest to listen for heart murmurs; the first five out of six are adjacent to the sternum. Each of these locations roughly correspond to a specific part of the heart. The locations are: 2nd right intercostal space, 2nd - 5th left intercostal spaces, and 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.
- The pitch of a murmur is low, medium or high and is determined by whether it can be auscultated best with the bell or diaphragm of a stethoscope.
- Some examples of the quality of a murmur are: blowing, harsh, rumbling and musical.
[edit] Continuous murmurs
Heart murmurs are most frequently organized by timing, into systolic heart murmurs and diastolic heart murmurs. However, continuous murmurs can not be directly placed into either category.[2]
These murmurs are due to blood flow from a high pressure chamber or vessel to a lower pressure system.
Patent ductus arteriosus. PDA is an abnormal connection between the aorta and the pulmonary artery, which normally should be closed in infancy. Since aortic pressure is higher than pulmonary pressure, a continuous murmur occurs, which is often described as a machinery murmur, or Gibson's murmur.
Aortopulmonary window.
shunts. Usually a left to right shunt through a small atrial septal defect in the presence of mitral valve obstruction.
[edit] Gradations of Murmurs
| Gradations of Murmurs | |
|---|---|
| Grade | Description |
| Grade 1 | Very faint, heard only after listener has "tuned in"; may not be heard in all positions. |
| Grade 2 | Quiet, but heard immediately after placing the stethoscope on the chest.. |
| Grade 3 | Moderately loud. |
| Grade 4 | Loud, with palpable thrill (ie, a tremor or vibration felt on palpation)[3] |
| 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. |
[edit] Interventions that change murmur sounds
- inspiration 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 [4] [5].
- abrupt standing
- squatting
- valsalva maneuver. One study found the valsalva maneuver to have a sensitivity of 65%, specificity of 96% in detecting Hypertrophic obstructive cardiomyopathy (HOCM) [4].
- hand grip
- post ectopic potentiation
- amyl nitrite
- methoxamine
- positioning of the patient. ie. positioning patients in the left lateral position will allow a murmur in the mitral area to be more pronounced.
[edit] See also
[edit] References
- ^ heart murmur at Dorland's Medical Dictionary
- ^ continuous murmur at Dorland's Medical Dictionary
- ^ "Medline Plus Medical Dictionary, definition of "cardiac thrill"".
- ^ a b Lembo N, Dell'Italia L, Crawford M, O'Rourke R (1988). "Bedside diagnosis of systolic murmurs". N Engl J Med 318 (24): 1572–8. 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.
[edit] External links
- 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.
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