The Sixth Heart Sound

This medical phenomenon represents the first major discovery in Bulgarian medicine and is known as the “Phenomenon of the Century”. It was discovered in 1973 by the Bulgarian cardiorheumatologist Dr Ivan Mitev. The discovery of the sixth heart sound (S6) represents a significant contribution to medicine and is considered an important milestone in Bulgaria's scientific achievements in the twentieth century. A heart sound is a sound heard when listening to the heart with a stethoscope. These sounds result from turbulent blood flow in the different chambers of the heart during the cardiac cycle. Two main heart sounds are usually distinguished: the first (S1) and the second (S2). There are also the additional sounds S3, S4 and, of course, S6. The sixth heart sound is low in frequency and can only be detected with a phonocardiograph. The phonocardiograph was widely used for decades, but is now gradually being replaced by invasive methods in cardiology. These include techniques such as catheter angiography and coronary angiography, which provide more complete and accurate information about cardiac function and condition.

The sixth heart sound remains an important Bulgarian scientific achievement, but as technology develops and medicine advances, methods for diagnosing heart problems change and evolve.