Heart sounds
| Heart sound | Cardiac cycle phase | Cause | Possible pathology |
|---|---|---|---|
| First (S1) | Start of ventricular systole | Closure of mitral and tricuspid (atrioventricular) valves | Loud S1 with opening snap - Mitral stenosis |
| Second (S2) | Start of ventricular diastole | Closure of aortic and pulmonary (semilunar) valves | Soft S2 - |
| Third (S3) | During ventricular diastole | Blood striking left ventricle during passive ventricular filling | Ventricular dilatation |
| Fourth (S4) | Late ventricular diastole Atrial systole |
Blood striking the left ventricle during active ventricular filling (atrial systole) | Aortic stenosis HOCM |
during diastole
- end diastolic pressure 4-7mmHg
- end diastolic volume 120ml
- semilunar valves closed, AV valves open
- 80-90% passive ventricular filling