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