<prompt> Cardiac event at the end of isometric relaxation phase:Atrioventricular valves openAtrioventricular valves closesCorresponds to peak of C wave in JVPCorresponds to T wave in ECG  <response>: Isometric relaxation - Semilunar valves have closed. - AV valves yet to open In isometric relaxation ventricular muscle continues to relax without change in ventricular volume Intraventricular pressure decreases back to the diastolic levels AV valves open JVP correlation to cardiac cycle A wave: Atrial contraction C wave: Beginning of ventricular contraction bulging of AV valves back towards atria V wave: Towards end of ventricular contraction X wave: Ventricular contraction Y wave: Atrial emptying tricuspid valve opens 