Herztöne
Herztöne, also known as heart sounds, are the noises generated by the heart valves closing during the cardiac cycle. These sounds are typically described as "lub-dub" and are fundamental to the physical examination of the cardiovascular system. The first heart sound, or S1, occurs at the beginning of ventricular systole and is caused by the closure of the atrioventricular valves, the mitral and tricuspid valves. The second heart sound, or S2, marks the beginning of ventricular diastole and is due to the closure of the semilunar valves, the aortic and pulmonary valves.
Variations in the intensity, duration, and timing of these sounds, as well as the presence of additional