Heart murmur classification
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Heart murmurs can be classified by seven different characteristics such as their "quality" (blowing, harsh, rumbling, musical), their "pitch" (high, low, or medium), their "intensity" or loudness, their "timing" in the heart cycle (diastolic or systolic), their "shape" or the variation in their intensity over time, their "location" or spot where they are heard best, their "radiation" or where the sound is transmitted to. An example would be classification of a murmur as "a harsh, rough, low pitched 3/6 systolic ejection murmur at the right upper sternal border that radiates to the carotids" which is consistent with aortic stenosis.
Quality
The quality of a murmur can be characterized as
- Blowing: Mitral regurgitation often has this quality
- Harsh: Aortic stenosis may have this quality
- Rumbling: Mitral stenosis may have this quality
- Musical
Pitch
The pitch of a murmur is either low, medium or high. Low pitched murmurs are best heard with the bell of the stethoscope while high pitched sounds are best heard with the diaphragm of the stethoscope.
Intensity
- Timing: Whether the murmur is a systolic or diastolic murmur. There is seldom any difficulty distinguishing between systole and diastole, because systole is considerably shorter at normal heart rates. At rapid heart rates, the examiner can usually time the murmur by simultaneous palpation of the lower right carotid artery or can rely on the fact that the S2 is usually the louder sound at the base. Once S2 is identified, murmurs can be located properly in the cardiac cycle as systolic or diastolic. The inching technique, popularized by Harvey and Levine, consists of slowly moving the stethoscope down from the base to the apex while repeatedly fixing the cardiac cycle in mind, using S2 as a reference point. In sinus tachycardia, carotid sinus pressure can temporarily slow the rate and make it possible to differentiate systole from diastole.
- Shape: Shape refers to the intensity over time; murmurs can be crescendo (increasing), decrescendo (diminishing), crescendo-decrescendo (increasing-decreasing or diamond shaped) and plateau (unchanged in intensity).
- Location: 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 to 5th left intercostal spaces, and 5th mid-clavicular intercostal space.
- Radiation: 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.
Timing of Murmur
The timing of heart murmurs can be broadly classified as either diastolic or systolic [1].
- Diastolic heart murmurs are not normal, while systolic heart murmurs may be normal or abnormal,
- Diastolic murmurs always require further evaluation,
- Systolic murmurs are most often benign, and are due to rapid flow rates,
- Systolic murmurs are not normal when accompanied by a heave.
Intensity of Murmur
Intensity refers to the loudness of the murmur, and it is graded on a scale from 0-6/6, with 6 being the loudest. [2]
| Gradations of Murmurs | 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 | Murmur is very loud, with palpable thrill. |
| Grade 5 | Murmur is extremely loud, with palpable thrill, and can be heard if only the edge of the stethoscope is in contact with the skin, but cannot be heard if the stethoscope is removed from the skin. |
| Grade 6 | Murmur is exceptionally loud, with palpable thrill, and can be heard with the stethoscope just removed from contact with the chest. |
Systolic thrills usually are associated with murmurs of grade 4 or louder. Systolic murmurs of grade 3 or more in intensity are usually hemodynamically significant. [3]
References
- ↑ Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:104-105 ISBN 140510368X
- ↑ Freeman AR, Levine SA. Clinical significance of systolic murmurs: study of 1000 consecutive "noncardiac" cases. Ann Intern Med. 1933, 6: 1371–85.
- ↑ Norton P, O'Rourke RA. Cardiac murmurs (Goldman L, Braunwald E, eds. Cardiology for the Primary Physician). 2nd ed. Philadelphia PA Saunders, 2003: 151-68