<prompt> At the end of the isometric relaxation phaseAtrioventricular valves openAtrioventricular valves closeCorresponds to C wave in JVPCorresponds to T wave in ECG  <response>: At the end of Isovolumetric relaxation, the intraventricular pressures drop to less than the atrial pressure resulting in the opening of Atrioventricular valves Ref : Ganong 25th edpage 539 