I33.9: Acute endocarditis, unspecified

The inner membrane of your heart is inflamed.

The heart is composed of a thick muscle layer and a thin membrane in the heart interior. An external sac, the pericardium, surrounds the heart. This sac consists of a tight membrane. The thin, inner membrane of your heart is inflamed. This usually affects the heart’s valves. The heart’s valves may then become leaky.

There are 4 valves in the heart. These valves ensure that the blood flows in the right direction. So they have to close tightly. They also have to open up fully so that the blood can be properly pumped out of the heart.

Inflammation of the heart can cause one to feel unwell, and have a high temperature or chest pain, for example.

Additional indicator

On medical documents, the ICD code is often appended by letters that indicate the diagnostic certainty or the affected side of the body.

  • G: Confirmed diagnosis
  • V: Tentative diagnosis
  • Z: Condition after
  • A: Excluded diagnosis
  • L: Left
  • R: Right
  • B: Both sides

Further information


This information is not intended for self-diagnosis and does not replace professional medical advice from a doctor. If you find an ICD code on a personal medical document, please also note the additional indicator used for diagnostic confidence.
Your doctor will assist you with any health-related questions and explain the ICD diagnosis code to you in a direct consultation if necessary.


Provided by the non-profit organization “Was hab’ ich?” gemeinnützige GmbH on behalf of the Federal Ministry of Health (BMG).