Heart sounds are generated by the turbulence in blood flow due to the closing of heart valves. These sounds are best perceived slightly away from the valves, where the blood flow disseminates the sound.
Auscultation is the process of listening to these internal body sounds using a stethoscope. The heart produces four types of sounds, but only two—S1 and S2—can usually be heard with a stethoscope.
S1, also known as the "lub" sound, is caused by the closure of atrioventricular (A-V) valves at the start of ventricular systole. It is characteristically louder and longer. S2, the "dub" sound, occurs due to the closure of semilunar valves at the beginning of ventricular diastole.
The other two sounds, S3 and S4, are usually inaudible and result from blood turbulence during ventricular filling and atrial systole.
Heart sounds offer insights into the heart's mechanical functioning. A heart murmur is an abnormal sound heard before, between, or after normal heart sounds, or it may mask them. In children, particularly between 2 and 4 years old, murmurs are common and usually harmless, often disappearing with growth. These are known as innocent or physiologic murmurs. However, in adults, murmurs typically signify a valve disorder. Stenosis is when the heart valve doesn't fully open or is too narrow, disrupting normal blood flow. Incompetence, on the other hand, occurs when the valve doesn't fully close, leading to a backflow or regurgitation of blood. Both conditions can cause distinctive murmurs, aiding in their diagnosis.
Heart sounds are mainly produced when valve closures cause turbulence in the blood.
These are best heard at chest locations slightly away from the valves as the blood disperses the sound.
Auscultation is listening to the body's internal sounds using a stethoscope.
The heart produces four types of sounds, but only two are audible with a stethoscope.
The first sound, S1, or the lubb sound, is caused by the closure of the AV valves when ventricular systole starts. It is louder and longer than other heart sounds.
S2, or the dupp sound, is due to the closure of the semilunar valves at the start of ventricular diastole.
The inaudible S3 and S4 are due to blood turbulence during ventricular filling and atrial systole.
Murmurs are abnormal heart sounds frequently observed in children and older people but can be pathological in adults.
An incompetent valve that fails to close completely is heard as a swishing sound on the stethoscope.
In contrast, a stenotic valve does not open completely, resulting in a rumbling sound.
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