timing of sounds and events in the cardiac cycle

Last reviewed 01/2018

• first sound: closure of AV valves, indicates the beginning of ventricular systole
• ejection sound:
• systolic ejection click: this is an early systolic high pitched sound heard over the aortic area - may occur in cases of congenital sclerosis where the aortic valve remains mobile
• non-ejection systolic click: high pitched sound heard during systle and best heard over the mitral area; may occur in mitral valve prolapse
• second sound: closure of semilunar valves, marks the beginning of diastole, which is generally longer than systole
• opening snap: opening of abnormal AV valves; occurs at a variable distance after the second sound
• third sound: ventricular filling (beginning); mid - diastolic heart sound
• fourth sound: ventricular filling with atrial contraction; late diastolic heart sound