Abnormal spirometry after the Fontan procedure is common and associated with impaired aerobic capacity

Abstract

Impaired exercise capacity is common after the Fontan procedure and is attributed to cardiovascular limits. The Fontan circulation, however, is also distinctively vulnerable to unfavorable lung mechanics. This study aimed to define the prevalence and physiological relevance of pulmonary dysfunction in patients with Fontan physiology. We analyzed data from the Pediatric Heart Network Fontan Cross-Sectional Study to assess the prevalence and pattern of abnormal spirometry in Fontan patients (6-18 yr old) and investigated the relationship between low forced vital capacity (FVC) and maximum exercise variables, including peak O2 consumption (Vo2peak), among those who demonstrated adequate effort (n = 260). Average ages at the time of exercise testing and Fontan completion were 13.2 ± 3.0 and 3.5 ± 2.2 yr old, respectively. Aerobic capacity was reduced (Vo2peak: 67.3 ± 15.6% predicted). FVC averaged 79.0 ± 14.8% predicted, with 45.8% having a FVC less then the lower limit of normal. Only 7.8% demonstrated obstructive spirometry. Patients with low FVC had lower Vo2peak (64.4 ± 15.9% vs. 69.7 ± 14.9% predicted, P < 0.01); low FVC independently predicted lower Vo2peak after adjusting for relevant covariates. Among those with Vo2peak < 80% predicted (n = 204/260), 22.5% demonstrated a pulmonary mechanical contribution to exercise limitation (breathing reserve < 20%). Those with both low FVC and ventilatory inefficiency (minute ventilation/CO2 production > 40) had markedly reduced Vo2peak (61.5 ± 15.3% vs. 72.0 ± 14.9% predicted, P < 0.01) and a higher prevalence of pulmonary mechanical limit compared with patients with normal FVC and efficient ventilation (36.1% vs. 4.8%). In conclusion, abnormal FVC is common in young patients after the Fontan procedure and is independently associated with reduced exercise capacity. A large subset has a pathologically low breathing reserve, consistent with a pulmonary mechanical contribution to exercise limitation.

Inspiratory Muscle Training Is Associated With Improved Inspiratory Muscle Strength, Resting Cardiac Output, and the Ventilatory Efficiency of Exercise in Patients With a Fontan Circulation

“…In a study of 52 adult atriopulmonary Fontan patients (mean age: 26.5 years [range: 18–45 years]; mean age at Fontan: 17.5 years [range: 5–36 years]), Fredriksen et al reported a percentage of predicted forced vital capacity (FVC) of 77% with much lower baseline exercise capacity (maximum VO 2 of 15.9 mL/kg per minute) than in our study . Opotowsky et al, in a study of 260 young Fontan patients (aged 13.2±3.0 years, 57 extracardiac conduit, 152 lateral tunnel, and 43 atriopulmonary connection) reported a percentage of predicted FVC of 79±14.8%, with FVC correlating with peak VO2 . Ohuchi et al, in a study of 101 younger Fontan patients (aged 13.6±4.6 years, 29 atriopulmonary type, and 72 lateral tunnel or extracardiac conduit) found lung function closer to that in our cohort (percentage of predicted FVC: 80±20%) .…”

Exercise Oscillatory Ventilation in Patients With Fontan Physiology

“…We have previously shown, in another sample of patients with Fontan circulation, that both low FVC and high V E /VCO 2 are associated with lower peak VO 2 . 30 In this study, EOV was associated with younger age and, likely as a consequence of this, smaller body size. This may be because of ongoing maturation of ventilatory regulation through adolescence.…”

Exercise testing and spirometry as predictors of mortality in congenital heart disease: Contrasting Fontan physiology with repaired tetralogy of Fallot

“…Few previous studies have examined the relationship between spirometric measurements and mortality in Fontan patients. Abnormal spirometry is reported to be common among patients who have had Fontan surgery, and is independently related to reduced exercise capacity . Furthermore, in a study exploring the relationship between exercise oscillatory ventilation and mortality in Fontan patients, FVC was found to be a strong univariable predictor of mortality .…”