Heart sounds

Heart sounds are what health professionals listen to in any basic diagnostic examination of a patient’s heart. Because the heart, as a blood pump, actually makes noises, listening carefully to that noise is the most efficient and effective way to detect basic problems. The familiar process in which an attending professional, such as a doctor or nurse, uses a stethoscope to listen to the heart is in fact a complex interaction that demands a very careful and precise ear, as different inflections of the heart’s basic beating can direct immediate problem diagnosis or help detect long-term conditions.

Given the short time frame of an individual heartbeat, listening to a heart may seem an inexact and even subjective sort of analysis. Yet with practice a physician can clearly and precisely hear where the heart is functioning efficiently and where there may be problems. Because the entire body depends on the regulation of blood flow from the heart, listening to heart sounds is a standard protocol for health professionals in all areas of medical diagnosis, from paramedics and first responders to nurses and doctors of all kinds.

Background

Ironically, heart disease is both the leading cause of death worldwide and among the most treatable conditions. Cardiovascular disease can reflect both genetics and lifestyle choices, and it affects people of all kinds. Because detecting heart irregularities—that is, listening for rate of beat, type of beat, and intensity of beat—is critical in early detection of patients at risk, the science and technology of auscultation, or listening to internal sounds of bodily organs, has grown to be one of the most sophisticated protocols in diagnostic medicine. Auscultation involves training one’s ear to recognize both normal and irregular sounds and sound patterns. This is a difficult task, considering that a stethoscope picks up all body sounds, not just those of the heart, and that sounds change significantly depending on stethoscope placement.

The heart has four valves: pulmonary, aortic, mitral, and tricuspid. Blood being pumped into and out of the heart relies on the effective cooperation of these four parts, which each make distinct noises. A health professional performing auscultation listens for particular elements of the heartbeat, typically using a specialized stethoscope—the traditional stethoscope with the bell and diaphragm requires redundant examination and can lead to fuzzy diagnoses—which is moved to different positions to focus on each valve and their sounds. In some cases, particularly first-responder situations in which medical equipment may not be present, the listener may hold their ear directly to the patient’s body. Additionally, advanced technology, such as the Doppler ultrasound, provide other forms of computerized auscultation that can complement traditional listening methods.

Overview

The standard heartbeat takes less than a second to occur. That requires health professionals to have very precise listening skills and the ability to sort out the elements of the heart’s operations. Therefore heart sounds are classified in a standard system to help listeners focus and differentiate normal and abnormal sounds. Cardiac diagnosticians separate the main sounds into first, second, third, and fourth heart sounds, represented by a capital letter "S" and the associated number. S1 and S2 refer to the first and second sounds of a standard, healthy heart—the tick and the tock, also called "lub and dub" or "lup and dup."

To the trained ear, the first heart sound is slightly louder, slightly greater. It is produced by the cooperation of the mitral and tricuspid valves (together known as the atrioventricular valves). S1 can be further broken down into the sounds produced by each valve, known as M1 and T1. In a functioning heart, the second heart sound is slightly less emphatic. It is produced by the action of the aortic and pulmonary valves (together known as the semilunar valves). S2 can also be broken down into separate parts for each valve: A2 and P2. The synchronization of A2 and P2 can become offset, a condition known as split S2; this can be normal in some cases, particularly in young patients, but can also be a sign of abnormality. Other abnormalities of the first and second heart sounds (too loud, too soft, or highly varied in intensity) are warning signs of various heart conditions.

The second and third heart sounds—S3 and S4—are not always present, and therefore help reveal particular problems with the heart’s operations if detected. In many cases these extra heart sounds are defined as irregular or pathological. In S3 the standard two heart sounds are complicated by a third, offbeat, low-frequency sound, causing a "gallop" pattern. The cardiac field has a range of word patterns to clarify this sound cadence: for instance, "lub-dub-bub," "Kentucky," or "slosh-ing-in." S3 is caused by higher heart pressure and rate of flow, which is a symptom of congestive heart failure and some other conditions, though it can be normal in children and young adults as the heart grows.

S4 is another low-frequency sound that causes a gallop pattern, with the extra sound coming between S1 and S2. This is often remembered through similar cadences such as "belub dup," "Tennessee" or "a-stiff-wall," the latter of which also hints at the sound’s cause—a pressure wave generated by a stiff ventricle. This may be caused by conditions including hypertension, cardiomyopathy, and aortic stenosis. While S3 in adults often requires immediate surgical attention, S4 usually indicates that the patient must make long-term adjustments in lifestyle—most notably diet and exercise—in order to bring the heart’s actions back to normal.

Beyond the four primary heart sounds, auscultation can also detect a variety of other atypical acoustic events. The names of these sounds, including murmurs, snaps, rubs, and clicks, might appear to be inexact, but a skilled listener can recognize each as distinct and understand their implications for heart health. In this way heart sounds help direct the specific protocols of cardiac care.

Bibliography

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