heart contraction measurement mitral valve closure to opening time 2014-08-18T12:19:05Z JSMITH MV co Measurement of the length of time between the closing of the mitral valve (the dual-flap valve in the heart that controls blood flow between the left atrium and the left ventricle) at the end of ventricular filling (that is, after atrial contraction) and its opening at the beginning of the next round of ventricular filling.