This site is intended for healthcare professionals

Go to /sign-in page

You can view 5 more pages before signing in

Loud first (1st) heart sound

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

A loud first heart sound occurs when the leaflets are wide open at the end of ventricular diastole and shut forcefully at the beginning of ventricular systole.

Possible causes of a loud first heart sound include:

  • late atrioventricular closure
    • this occurs when there is rapid flow at the end of diastole e.g. mitral stenosis, the short diastole of tachycardic states and left to right shunts
    • where the P-R interval is less than 0.12 s. This situation results in an opened valve that is not closed at the time of ventricular contraction.

Hence:

  • atrial fibrillation
  • short diastole - tachycardia
  • atrial premature beat
  • mitral stenosis where high left atrial pressure delays mitral valve closure

Related pages

Create an account to add page annotations

Annotations allow you to add information to this page that would be handy to have on hand during a consultation. E.g. a website or number. This information will always show when you visit this page.