Systolic Murmurs Mitral Regurgitation Lesson Waveform Anatomy play pause Table of Contents 1Innocent Murmur 2Aortic Sclerosis (Musical Murmur) 3Aortic Stenosis -Mild 4Aortic Stenosis - Severe #2 5Mitral Regurgitation 6Mitral Valve Prolapse (Click with Late Systolic Murmur) 7Hypertrophic Cardiomyopathy Practice Quiz This video is an animation of Mitral Regurgitation A#26 (lesson# 5) within course number 5. The murmur of mitral regurgitation is a mid-frequency, rectangular murmur taking up all of systole. S1 is normal. S2 is single.There is a third heart sound gallop in diastole.Both the left ventricle and the left atrium are enlarged. The murmur is caused by turbulent flow through the incompetent mitral valve leaflets into the left atrium.