Cardiopulmonary interaction in heart failure

In heart failure lung dysfunction is frequent and is greater the greater the heart failure severity. It can be evaluated in terms of lung mechanics and gas diffusion. Indeed heart–lung interaction is related to heart dimensions and lung fluid content; furthermore heart–lung interaction is influenced by the body position. Lung diffusion is also altered in patients with chronic heart failure, and a low gas diffusion is associated with a reduced performance. During exercise, heart–lung interaction becomes more evident. Heart failure patients show an abnormal hyperventilation due to a progressively increased respiratory rate, and a lower tidal volume; hyperventilation is due to different causes including enhanced responses from chemo- and metabolo-receptors, increased CO2 production and increased dead space ventilation. Several drugs affect the ventilatory pattern in heart failure patients: ACE-inhibitors and anti-aldosteronic drugs improve lung diffusion and ventilatory efficiency during exercise; beta-blockers reduce exercise-induced hyperventilation. Furthermore, ultrafiltration improves lung mechanics, both at rest and during exercise, through body fluid content reduction.