A heart murmur is an abnormal swishing or whooshing noise that occurs when the heart beats. In order to properly diagnose a heart murmur, there are several aspects of the murmur that must be taken into consideration. Here is a look at how heart murmurs are graded and categorized.
The intensity, or volume, of a heart murmur is graded using the Levine Scale, which rates them from of 1 to 6. 1 refers to a very quiet heart murmur, while a level 6 murmur would be the loudest possible. Innocent heart murmurs, or those that occur in an otherwise healthy individual, generally rank on the lower end of the scale—they are rarely graded above a 3.
Chapter 26 by Martin A Alpert of Clinical Methods: The History, Physical, and Laboratory Examinations breaks down the grading system as follows:
- Grade 1: Very faint and requires some effort to hear
- Grade 2: Still quiet, but obviously present without any special work
- Grade 3: The beginnings of louder murmurs
- Grade 4: Considered to be very loud; palpable thrills usually accompany murmurs at this grade or higher
- Grade 5: So loud it’s audible with only an edge of the stethoscope on the chest
- Grade 6: Murmurs so loud the stethoscope doesn’t have to touch the chest to pick up the sound.
Other aspects of a heart murmur that are crucial to an accurate diagnosis and potential treatment program include frequency (or pitch), quality, duration, configuration (or shape), location, and radiation. Frequency or pitch refers to how high or low the sound is. It directly corresponds to how fast the blood is moving at the spot where the murmur is coming from; faster movement causes a higher pitch, while slower movement causes a lower pitch. Quality is descriptive of what kind of a sound the murmur is. This might be whooping, honking, blowing, squeaking, rumbling, or other tonal adjectives.
Duration refers to which part of the heartbeat the murmur occurs through: murmurs may be systolic (beginning with the first heart sound, or during contraction), diastolic (starting with the second heart sound, or relaxation), or continuous (occurring with both). Each of these must then be defined by their duration—whether it begins with the first heart sound and ends before the second heart sound begins, or continues on through the second heart sound, or further. There are several classifications for duration.
The configuration of a heart murmur refers not to the shape of the heart, but to the shape of the sound of the murmur. This might mean it begins quiet and gets louder (a crescendo), vice versa, or any other configuration of audibility. The location of the murmur is the spot in the heart or chest from which the murmur is the loudest. Because the location may spread over multiple areas, finding an exact point of location can help figure out exactly where the murmur is originating from. The radiation of the heart murmur is essentially which parts of the heart the sound can still be heard from, or where the sound radiates to. This is not applicable to every heart murmur.