The first heart sound, or S1, is the "lub" of a normal heartbeat. It's a high-pitched sound that occurs at the beginning of systole—when the heart pumps blood out of the heart into the lungs or body.

Midsystolic murmurs — also known as systolic ejection murmurs, or SEM — include the murmurs of aortic stenosis, pulmonic stenosis, hypertrophic obstructive cardiomyopathy and atrial septal defects. A ...

IT IS possible that the existence of the heart sounds was known to Hippocrates 1 and even that he made use of his knowledge for diagnostic purposes, but William Harvey 2 seems to have been the first ...