How does heart failure relate to pulmonary congestion?

Heart failure is a condition characterized by the heart's inability to pump blood effectively, leading to a range of physiological changes. One of the significant consequences of heart failure, particularly left-sided heart failure, is pulmonary congestion. This occurs because the weakened heart cannot efficiently move blood out of the left ventricle and into systemic circulation, causing blood to back up into the pulmonary veins.

As pressure builds in the pulmonary circulation, fluid is pushed out of the capillaries into the interstitial spaces and alveoli of the lungs, which results in pulmonary congestion. This fluid accumulation can cause symptoms such as shortness of breath and decreased oxygen exchange, notably worsening respiratory function. Hence, the correct understanding of the relationship between heart failure and pulmonary congestion is that heart failure leads to fluid accumulation in the lungs.