Pathophysiology and treatment of alveolar-capillary dysfunction in chronic heart failure

Heart failure increases the resistance to gas transfer across the alveolar-capillary membrane. Disruption of the alveolar anatomical configuration and impairment of cellular pathways involved in the fluid-flux regulation and gas-exchange efficiency (i.e., 'stress failure' of the alveolar-capillary membrane) has been well characterized in different experimental settings of vascular-capillary injury. In heart failure, the appreciation of the pathophysiologic relevance of alveolar stress failure continues to grow. Alveolar-capillary membrane conductance and capillary blood volume are the subcomponents of lung-diffusion capacity. An alveolar-capillary membrane conductance reduction with a trend of capillary blood volume to increase and with consequent impairment of gas exchange, are typical of the heart-failure syndrome. Alveolar-capillary membrane conductance abnormalities have been shown to reflect the underlying lung-tissue damage, to bring an independent prognostic information and to play a significant role in the pathogenesis of exercise limitation and ventilatory abnormalities. This review focuses on the current knowledge on this topic.