At the end of the isometric relaxation phase
Atrioventricular valves open
Atrioventricular valves close
Corresponds to "C" wave in JVP
Corresponds to T wave in ECG
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 ed/page 539
Cardiovascular system