What are the causes of oedema in congestive heart failure?

Answer 1

Oedema with congestive heart failure typically occurs when there has been right sided heart failure. Left sided HF can, however, often also lead to right sided heart failure. Basically, when RSHF occurs, the ventricle is not contracting with the same strength that it once used to. Overtime, this causes the backflow of blood from the right ventricle, artrium and into the vessels supplying this structure. This backflow causes increased pressure of blood in the vessels which are bringing blood to the heart. So, you get what is called 'increased capillary hydrostatic pressure' which just means increased pressure within the peripheral capillaries due to increased blood backflow. This causes transudate formation - some of the plasma from the capillaries is pushed out and into the interstitial spaces (spaces within the cells). This causes increased build up of fluid within the interstitial spaces and therefore oedema.