Changes in the lungs in heart failure

In acute heart failure the high pressure in pulmonary veins causes a series of pathological changes in the lungs:

• interstitial fluid causes stiffening of the lungs and increases the work of breathing
• oedema of the walls of airways may cause non-asthmatic airways obstruction
• oedema of alveolar walls may impede gaseous exchange
• frank fluid in the alveoli results in gross hypoxaemia and lung crepitations

In the well-diuresed patient with chronic heart failure there are no gross changes in lung structure or function. There may be increased fatiguability of respiratory muscles.