The patient's position should be supine.
This case presents an example of a pansystolic murmur usually associated with mitral regurgitation.
The murmur 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.
In the anatomy video, observe the enlarged left ventricle and left atrium and turbulent flow from the left ventricle into the left atrium, creating the murmur.