Impairments in Pulmonary Function in Fontan Patients: Their Causes and Consequences

Abstract

Patients with a Fontan circulation lack a sub-pulmonary ventricle with pulmonary blood flow passively redirected to the lungs. In the Fontan circulation, ventilation has a significant influence on pulmonary blood flow and cardiac output both at rest and with exercise. Children and adults with a Fontan circulation have abnormalities in lung function. In particular, restrictive ventilatory patterns, as measured by spirometry, and impaired gas transfer, as measured by the diffusing capacity of carbon monoxide, have been frequently observed. These abnormalities in lung function are associated with reduced exercise capacity and quality of life. Moderate to severe impairment in lung volumes is independently associated with reduced survival in adults with congenital heart disease. Skeletal and inspiratory muscle weakness has also been reported in patients with a Fontan circulation, with the prospect of improving respiratory muscle function through exercise training programs. In this review, we will present data on cardiopulmonary interactions in the Fontan circulation, the prevalence and severity of impaired lung function, and respiratory muscle function in this population. We will discuss potential causes for and consequence of respiratory impairments, and their impact on exercise capacity and longer-term Fontan outcome. We aim to shed light on possible strategies to reduce morbidity by improving respiratory function in this growing population of patients.

Lung Function in Fontan Patients Over a Ten-Year Period: Is the Fontan Circulation Impairing Lung Development?

“…Studies investigating lung function in Fontan patients are limited, but it seems evident that impaired lung function is common [ 10 , 11 , 13 , 14 , 28 ]. In our study, we observed a restrictive lung pattern and a severely reduced DLCO and DLNO in both PFT-I and PFT-II, consistent with previous reports [ 29 ]. To our knowledge, no previous longitudinal studies are available for comparison of the development of lung function over time in Fontan patients.…”

“…The exact pathophysiology behind the impaired lung function in Fontan patients remains unclear, but several concepts are discussed in a 2022 review by Laohachai and Ayers [ 29 ]. The negative impact of a non-pulsatile pulmonary flow on lung function is the most discussed theory.…”

“…In the review by Laohachai and Ayers, it is further discussed whether an abnormal pulmonary flow can cause an impaired development of the alveoli as the patients grow [ 29 ]. Alterations in the pulmonary vasculature in Fontan patients begin in utero, as a result of the congenital heart malformation [ 5 ].…”

Possible effects of left pulmonary artery stenting in single ventricle patients on bronchial area, lung volume and lung function

“…In the Fontan circulation, a preserved inspiratory function is more important than in other patients ( 16 ). In contrast to biventricular circulation, in Fontan patients, inspiration represents the main driving force for atrial and ventricular filling and therefore the most critical component for cardiac output at rest and during exercise, whereas myocardial contraction acts as a pump for forward flow ( 3 , 16 ). A restrictive pattern of lung function is frequently found in Fontan patients ( 13 , 14 ) and has been described to correlate with reduced exercise capacity and quality of life ( 15 , 16 ).…”

“…In contrast to biventricular circulation, in Fontan patients, inspiration represents the main driving force for atrial and ventricular filling and therefore the most critical component for cardiac output at rest and during exercise, whereas myocardial contraction acts as a pump for forward flow ( 3 , 16 ). A restrictive pattern of lung function is frequently found in Fontan patients ( 13 , 14 ) and has been described to correlate with reduced exercise capacity and quality of life ( 15 , 16 ). In our study, we found a similarly high prevalence of restrictive lung disease, with up to 33% of patients with pathologically diminished FVC.…”