Auscultogram from normal and abnormal heart sounds
Murmurs are pathologic 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 are benign (an "innocent murmur").
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 left 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 according to the Levine scale, from 1 to 6:
- The murmur is only audible on listening carefully for some time.
- The murmur is faint but immediately audible on placing the stethoscope on the chest.
- A loud murmur readily audible but with no palpable thrill.
- A loud murmur with a palpable thrill.
- A loud murmur with a palpable thrill. The murmur is so loud that it is audible with only the rim of the stethoscope touching the chest.
- A loud murmur with a palpable thrill. The murmur is audible with the stethoscope not touching the chest but lifted just off it.
- Pitch may 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.
A mnemonic to remember what characteristics to look for when listening to murmurs is SCRIPT: Site, Configuration (shape), Radiation, Intensity, Pitch and quality, and Timing in the cardiac cycle.
The use of two simple mnemonics may help differentiate systolic and diastolic murmurs; PASS and PAID. Pulmonary and aortic stenoses are systolic while pulmonary and aortic insufficiencies (regurgitation) are diastolic. Mitral and tricuspid defects are opposite.
Interventions that change murmur sounds
- Inhalation leads to drop in intrathoracic pressure, which increases the capacity of pulmonary circulation, 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. specifically positive Carvallo's sign describes the increase in intensity of a tricuspid regurgitation murmur with inspiration.
- abrupt standing
- Squatting, by increasing preload
- Handgrip maneuver, by increasing afterload
- Valsalva maneuver. One study found the Valsalva maneuver to have a sensitivity of 65%, specificity of 96% in detecting hypertrophic obstructive cardiomyopathy (HOCM). Both standing and Valsalva maneuver will decrease venous return and subsequently decrease left ventricular filling, resulting in an increase in the loudness of the murmur of hypertrophic cardiomyopathy, since outflow obstruction is increased by decreasing preload. Alternatively, squatting increases systemic vascular resistance, increasing afterload and helping to hold the obstuction in a more open configuration, decreasing the murmur. Maximum handgrip exercise also results in a increased loudness of the murmur.
- post ectopic potentiation
- amyl nitrite
- positioning of the patient. That is, putting 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.
- Ventricular septal defect, rooster sounds
- Symptoms are holosystolic, heard best at left lower sternal border.
Murmur Types and Disease Associations
- Continuous Machinery Murmur, at the left upper sternal border
- Classic for a patent ductus arteriosus, and in serious cases associated with poor feeding, failure to thrive and respiratory distress. Other examination findings may include widened pulse pressures and bounding pulses.
- Systolic Murmur loudest below the left scapula
- Classic for a coarctation of the aorta which is often seen in Turner's Syndrome, (gonadal dysgenesis), an X-linked disorder with a part missing of the X-chromosome. Other findings of this murmur is radio-femoral delay, and different blood pressures in the upper and lower extremities.
- Harsh holosystolic murmur at the left lower sternal border
- Classic for a ventricular septal defect. It is in these children that the delayed-onset cyanotic heart disease occurs known as Eisenmenger syndrome, which is a reversal of the left-to-right heart shunt as the right ventricle hypertrophies, causing a right-to-left shunt and resulting cyanosis.
- Widely split fixed S2 and systolic ejection murmur at the left upper sternal border
- Classically due to a patent foramen ovale or atrial septal defect, which is lack of closure of the foramen ovale. This produces a left-to-right shunt initially, thus does not produce cyanosis, but causes pulmonary hypertension. Longstanding uncorrected atrial septal defects can also result in Eisenmenger's syndrome with resultant cyanosis.
Cooing dove murmur
The cooing dove murmur is a cardiac murmur with a musical quality (high pitched - hence the name) and is associated with aortic valve regurgitation. It is a diastolic murmur which can be heard over the mid-precordium.
- "heart murmur" at Dorland's Medical Dictionary
- "continuous murmur" at Dorland's Medical Dictionary
- "Heart murmur: characteristics". LifeHugger. Retrieved 2009-09-23.
- Orient JM. "Chapter 17: The Heart". Sapira's Art & Science of Bedside Diagnosis (4th ed.). Philadelphia: Wolters Kluwers Health. p. 339. ISBN 978-1-60547-411-3.
- Freeman AR, Levine SA (1933). "Clinical significance of systolic murmurs: Study of 1000 consecutive "noncardiac" cases.". Ann Intern Med 6: 1371–1379.
- "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.
- Harrison's Internal Medicine 17th, chapter 5, "Disorders of the cardiovascular system," question 32, self assessment and board review
- Harrison's Internal Medicine 17th, chapter 5, "Disorders of the cardiovascular system," question 86-87, self assessment and board review
- Information on heart murmurs in children from Seattle Children's Heart Center
- Heart Murmurs in Pediatric Patients
- Lehrer, Steven. Understanding Pediatric Heart Sounds. Elsevier 2002.
- Hanifin, Christopher. Heart Sounds: A Cardiac Auscultation Primer. CreateSpace, 2010
- Texas Heart Institute Scroll down to listen to heart murmurs.
- The Auscultation Assistant Provides recordings of heart murmurs.
- Heart murmurs in children information for parents.