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Cardiac Murmurs:
Published on Patient Care Online (http://www.patientcareonline.com)
Cardiac Murmurs:
March 01, 2004 | Atrial Fibrillation [1], Anemia [2], Hypertension [3]
ABSTRACT: The auscultatory features of heart murmurs-intensity, frequency, quality,
configuration, timing, duration, and radiation-can help identify a variety of cardiac
disorders. Systolic ejection murmurs have a crescendo-decrescendo configuration. These
include innocent murmurs and those associated with aortic stenosis and hypertrophic
cardiomyopathy. Systolic murmurs associated with retrograde flow from a high-pressure
chamber to a low-pressure chamber usually have a holosystolic configuration. Examples
of holosystolic murmurs include mitral regurgitation, tricuspid regurgitation, and the
murmur associated with a ventricular septal defect. Diastolic murmurs include
regurgitant murmurs, such as the decrescendo murmur of aortic regurgitation, and filling
murmurs, such as the presystolic rumble of mitral stenosis, which is preceded by an
opening snap. The murmur associated with patent ductus arteriosus is continuous.
Despite impressive recent advances in noninvasive cardiac testing, the physical examination
remains the cornerstone of any cardiac evaluation. Auscultation of the heart can provide important
clues to the diagnosis of valvular heart disease, congestive heart failure, congenital heart lesions,
and other cardiac abnormalities.
Here I provide a concise guide to the distinguishing auscultatory features of common heart murmurs
(Table). I also review the relationship between these findings and specific cardiac problems.
AUSCULTATION OF MURMURS: A BRIEF REVIEW
For best results, minimize ambient noise during auscultation and use a stethoscope equipped with a
dia- phragm and a bell. The diaphragm detects high-frequency sounds, such as systolic ejection
murmurs, while the bell detects low-frequency sounds, such as the rumble of mitral stenosis.
Use a systematic approach when listening to the heart.1 First, auscultate at the right upper sternal
border, next at the left upper sternal border; then proceed down the left sternal border. The final
point of auscultation is the apex. The reverse sequence is also appropriate. Each point of
auscultation correlates with one of the cardiac valves (Figure 1).
If you have difficulty in distinguishing between the first and second heart sounds at the apex, listen
carefully at the left upper sternal border, where the second heart sound splits on inspiration and is
usually louder than the first. Then, while keeping your focus on the rhythm of the heart, move the
stethoscope slowly toward the lower left sternal border. This process is known as "inching."2
Descriptions of heart murmurs include identification of the following features:
Intensity.
Frequency.
Quality.
Configuration.
Timing.
Duration.
Location and radiation.
Intensity (loudness). This is graded on a 6-point scale. Grade 1 murmurs are very faint and heard
only after you focus on the sound. Grade 2 murmurs are faint but heard as soon as you place the
stethoscope on the precordium. Grade 3 murmurs are moderately loud. Grade 4 murmurs are loud.
Grade 5 murmurs are very loud and can be heard with the stethoscope partly off the precordium.
Grade 6 murmurs can be heard with the stethoscope slightlyoff the precordium.
Frequency. Murmurs are described as high-pitched (eg, the murmur of aortic regurgitation) or
low-pitched (eg, the rumble of mitral stenosis).
Quality. A description of the quality of the sound heard helps further identify a murmur. For
example, the murmur of mitral stenosis is frequently described as a rumble, and that of mitral
regurgitation as "blowing."
Configuration, timing, and duration. These features are best described by means of diagrams.
For example, a diagram of the murmur of aortic stenosis-a crescendo-decrescendo murmur-depicts
its configuration as a diamond shape (Figure 2). Although a few murmurs are continuous, most
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Cardiac Murmurs:
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murmurs are either systolic or diastolic. A diagram of the murmur of mitral prolapse-a late systolic
murmur-uses a line graph to show when, relative to S1 and S2, the murmur begins.
Location and radiation. Murmurs associated with valvular stenosis are most audible at the point of
auscultation that correlates with the affected cardiac valve (see Figure 1). The murmur of aortic
stenosis is heard best at the second right intercostal space parasternally. The murmur of pulmonary
stenosis is most audible at the second or third intercostal space parasternally. The murmur of
tricuspid stenosis is heard best along the lower left sternal border. Finally, the murmur of mitral
stenosis is most audible at the apex.
Murmurs of regurgitation can radiate far from the point of origin. The murmur of aortic regurgitation
originates over the aortic area but radiates to the apex. The murmur of mitral regurgitation
originates at the apex and radiates to the axilla.
SYSTOLIC MURMURS
Systolic ejection murmurs. These are described as crescendo- decrescendo murmurs; their
intensity peaks in early or mid systole(see Figure 2). Ejection murmurs result from some type of
outflow obstruction. Important causes include aortic stenosis, pulmonary stenosis, and hypertrophic
obstructive cardiomyopathy. Systolic ejection murmurs can also occur in conditions of high cardiac
output, such as anemia and thyrotoxicosis.
Innocent murmur.This is the most common murmur in school-aged children.3 The innocent murmur
is a crescendo-decrescendo early systolic murmur that isheard best at the left lower sternal border.
The murmur does not radiate and is usually grade 1 or 2. Although there is some controversy about
the origin of innocent murmurs, one widely held opinion is that they result from turbulent blood flow
generated by left ventricular ejection of blood. When an innocent murmur is heard in an older
patient, evaluate for anemia, which causes high cardiac output and can thus generate a flow
murmur.
Aortic stenosis. The murmur of mildaortic stenosis is an ejection murmur that peaks early in systole.
It is harsh in quality and medium-pitched. It is heard best at the second right intercostal space and
often radiates to the neck. As the severity of the stenosis worsens, the murmur peaks later in
systole, and the A2 component of the second heart sound decreases in intensity and is delayed. This
delay results in paradoxical (reversed) splitting of S2 and the merging of A2 and P2 on inspiration
(Figure 3). Causes of aortic stenosis include congenital bicuspid aortic valve, rheumatic fever, and
aortic sclerosis.
Hypertrophic cardiomyopathy.This condition leads to outflow obstruction at mid systole, as the mitral
valve approximates the hypertrophied septum; the obstruction produces turbulent ejection of blood
from the left ventricle. The resulting murmur is harsh and is heard best at the left lower sternal
border. It typically becomes louder when the Valsalva maneuver is performed (because this
maneuver worsens the obstruction by decreasing venous return and making the left ventricle
smaller).4
Atrial septal defect. This produces left-to-right shunting in the atria, which in turn causes increased
filling of the right ventricle and consequently, increased flow across the pulmonic valve. The
increased flow producesa systolic ejection murmur that is heard best at the left sternal border across
the pulmonic valve area. With large atrial septal defects, there is also excess blood flow across the
tricuspid valve, which results in a mid-diastolic murmur at the left lower sternal border.3 S2 is widely
split and fixed.
Holosystolic murmurs. Holosystolic (pansystolic) murmurs (see Figure 2) result from retrograde
flow out of a high-pressure chamber into a low-pressure chamber. Common causes of holosystolic
murmurs include mitral insufficiency, tricuspid insufficiency, and ventricular septal defect.
Mitral regurgitation.The murmur of mitral regurgitation is generated when blood regurgitates from
the left ventricle into the left atrium. This holosystolic murmur is a blowing sound that is heard best
at the apex and radiates to the axilla. The first heart sound is often soft. Causes of mitral
regurgitation include infective endocarditis, degenerative valvular disease (mitral valve prolapse),
and rheumatic heart disease. If mitral valve prolapse is the cause, there may be a mid-systolic click
followed by a late systolic murmur.
Tricuspid regurgitation.The murmur of tricuspid regurgitation is a holosystolic murmur of medium
pitch that is heard best at the left lower sternal border and that may radiate to the right side of the
sternum. The most common cause of tricuspid regurgitation is right ventricular failure, which results
in chamber dilation and consequent enlargement of the tricuspid orifice.
Ventricular septal defect.This congenital lesion results in a persistent opening of the interventricular
septum that allows blood to pass from the high-pressure left ventricle into the low-pressure right
ventricle.5 The resulting murmur is a holosystolic murmur heard best along the left lower sternal
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border. When loud, it is harsh.
DIASTOLIC MURMURS
Diastolic regurgitant murmurs, which include aortic regurgitation murmurs and pulmonic valve
regurgitation murmurs, result from retrograde flow across an incompetent valve. Diastolic filling
murmurs, such as the murmur of mitral stenosis, result from turbulent flow across a valve (typically
the mitral or tricuspid valve).
Aortic regurgitation. The murmur associated with aortic insufficiency occurs when the aortic valve
fails to close completely and blood regurgitates from the aorta back into the left ventricle. It is a
high-pitched decrescendo murmur that is heard best along the left lower sternal border and
sternum.(Figure 4).
Two other murmurs may be associated with aortic regurgitation. The first of these is a systolic
ejection murmur that results when volume overload of the left ventricle causes increased flow across
the aortic valve. The second associated murmur is the Austin Flint murmur, a low-pitched
mid-diastolic sound that is heard at the apex. Austin Flint murmurs are generated by impingement of
the regurgitant flow on the anterior leaflet of the mitral valve.
Mitral stenosis. The murmur associated with mitral stenosis is a low-pitched diastolic rumbling
sound with presystolic accentuation; it is usually preceded by an opening snap just after S2 (see
Figure 4). The murmur is located at the apex and is heard best with the bell. Rheumatic heart
disease is the most common underlying cause.
CONTINUOUS MURMURS
Continuous murmurs begin in systole and continue through diastole. A classic example of a
continuous murmur is that associated with patent ductus arteriosus. The murmur is caused by a
continuous high-pressure shunt-blood flowing from the aorta through the patent ductus and into the
pulmonary artery, during both systole and diastole. The murmur is heard over the second left
intercostal space and is described as a continuous, rough, "machinery-type" sound.3 n
References:
REFERENCES:
1. Karnath B, Thornton W. Auscultation of the heart. Hosp Physician. 2002;38:39-43.
2. Harvey WP. Cardiac pearls. Dis Mon. 1994;40: 41-113.
3. Engle MA. Heart sounds and murmurs in diagnosis of heart disease. Pediatr Ann. 1981;10:84-93.
4. Stapleton J. Manipulating cardiac murmurs. Chest. 1982;81:135-136.
5. Moodie DS. Diagnosis and management of congenital heart disease in the adult. Cardiol Rev.
2001;9: 276-281.
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[3] http://www.patientcareonline.com/hypertension
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