Sydänääniä

Sydänääniä refers to the sounds produced by the heart during the cardiac cycle. These sounds are primarily generated by the closure of heart valves. The normal heart sounds are typically described as "lub-dub".

The first heart sound, or "lub," is caused by the closure of the atrioventricular valves, namely the mitral and tricuspid valves. This closure occurs at the beginning of ventricular systole, when the ventricles contract and push blood into the aorta and pulmonary artery. The "lub" sound is generally longer and lower in pitch than the second heart sound.

The second heart sound, or "dub," is produced by the closure of the semilunar valves, the aortic and pulmonary valves. This closure happens at the end of ventricular systole, as the ventricles begin to relax. The "dub" sound is typically shorter and higher in pitch.

Variations or additional sounds can sometimes be heard. A third heart sound, or S3, can occur in early diastole due to rapid ventricular filling. A fourth heart sound, or S4, can occur in late diastole just before the first heart sound, caused by atrial contraction pushing blood into a stiff ventricle. These extra sounds, if present, can indicate underlying cardiac conditions.

Listening to heart sounds with a stethoscope is a fundamental part of a physical examination. Physicians use auscultation to assess heart function and detect abnormalities. The timing, loudness, and presence of any extra sounds can provide valuable diagnostic information about valvular heart disease, heart failure, and other cardiovascular issues. The interpretation of heart sounds requires training and experience.