Murmur Fundamentals
PRETEST 
1. How does turbulent blood flow produce murmurs?
2. What are the seven characteristics used to describe murmurs?
3. What is the six-point graded scale?
4. What is a murmur’s configuration?
TURBULENT BLOOD FLOW
Whereas heart sounds are produced by brief vibrations that correspond to the beginning and end of systole, murmurs are produced by a prolonged series of vibrations that occurs during systole, diastole, or both. These vibrations result from turbulent blood flow.
Several clinically significant conditions—such as blood flowing at a high velocity through a partially obstructed opening, blood flowing from a higher-pressure chamber to a lower-pressure one, or any combination of these—can cause turbulent blood flow.
AGE ISSUEInnocent murmurs, such as Still’s murmur, are commonly heard in young children; they typically disappear in puberty. Pathognomonic heart murmurs in infants and young children usually result from congenital heart disease, such as atrial and ventricular septal defects. Other murmurs heard in pediatric patients can be acquired, such as with rheumatic heart disease.
CHARACTERISTICS
Murmurs, like other heart sounds, are described by their audible characteristics identified during auscultation. The terms used to describe a specific characteristic are determined primarily by the volume and speed of the jet of blood as it moves through the heart.
The seven characteristics used to describe murmurs are location, intensity, duration, pitch, quality, timing, and configuration.
AUSCULTATION TIPInitially, learn to identify the location and timing of murmurs. As your auscultation techniques improve, try to identify the intensity, duration, pitch, quality, and configuration.
AGE ISSUEWhen listening to heart sounds in the pediatric patient, take into account that exercise, crying, fever, and position changes can accentuate murmurs.
Location
A murmur’s location is the anatomic area on the chest wall where the murmur is heard best and is usually also the murmur’s point of maximum intensity. This area usually correlates with the underlying location of the valve that’s responsible for producing the murmur. For example, an aortic stenosis murmur is usually heard best near the heart’s base over the aortic area, whereas a mitral regurgitation murmur is usually heard best near the heart’s apex over the mitral area.
The murmur’s sounds may also be transmitted to the chamber or vessel where the turbulent blood flow occurs. This phenomenon, known as radiation, occurs because the direction of blood flow determines sound transmission. Murmurs radiate in either a forward or a backward direction.
Intensity
Intensity refers to a murmur’s loudness. It’s influenced by many factors, including body weight. For example, because the transmission of heart sounds to the chest wall is affected by chest wall thickness and by certain diseases, heart sounds and murmurs are usually louder in thin individuals and fainter in obese individuals. They’re also fainter in patients with emphysema.
Hyperdynamic states, decreased blood viscosity, increased pressure gradients across valves, larger jets of blood, and faster heart rates may also increase a murmur’s intensity. Murmurs are less intense in hypodynamic states and in patients with an elevated hematocrit.
Documenting intensity
Document a murmur’s intensity using a uniform method. Most health care professionals use a six-point graded scale, with 1 being the faintest intensity and 6 being the loudest. A grade 1 murmur is faint, may be heard intermittently, and is barely heard through the stethoscope. A grade 2 murmur is also faint but is usually heard as soon as the stethoscope is placed on the chest wall. A grade 3 murmur is easily heard and is described as moderately loud. A grade 4 murmur is loud and is usually associated with a palpable vibration known as a thrill. It may also radiate in the direction of blood flow. A grade 5 murmur is loud enough to be heard with only an edge of the stethoscope touching the chest wall; it’s almost always accompanied by a thrill and radiation. A grade 6 murmur is so loud that it can be heard with the stethoscope close to, but not touching, the chest wall; it’s always accompanied by a thrill, and it radiates to distant structures. Both grade 5 and 6 may even be heard without the aid of a stethoscope.
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