Normal Heart Sounds Innocent Murmur Lesson Waveform Anatomy play pause Table of Contents 1First and Second Heart Sounds - Normal and Unsplit 2First Heart Sound (Minimally Split) 3Second Heart Sound - Physiologically Split #1 4Third Heart Sound - Physiologic 5Innocent Murmur 6Exercise - Heart Rate 120 Practice Quiz This video is an animation of Innocent Murmur A#22 (lesson# 5) within course number 5. This is an example of an innocent murmur.This type of murmur is seen with non-cardiac conditions such as pregnancy, hyperthyroidism, exercise and anemia. When these are treated appropriately the systolic murmur disappears.The murmur is heard in early systole, is of short duration and has a frequency range of 120 hz to 250 hz. It is best auscultated in the pulmonic area and increases in intensity with inspiration. It can be heard with either the bell or diaphragm.In this example S1 and S2 are normal. Diastole is silent.The short duration and mid-range frequency characterize an innocent murmur.