First Heart Sound (Markedly Split) Reference Guide

First Heart Sound (Markedly Split)

If the splitting of the first heart sound is large (about 50 milliseconds) it is an indication of an abnormal condition called Right Bundle Branch Block. The splitting is most clearly heard at the tricuspid area. In the mitral valve area, the mitral component is louder. At 50 milliseconds, the splitting of the first heart sound is clearly audible.