title: 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.
authors.affiliation: Department of Cardiology, Boston Children's Hospital, Boston, Massachusetts; Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts; alexander.opotowsky@chboston.org.
authors.forename: Alexander R
authors.initials: AR
authors.lastname: Opotowsky
authors.affiliation: Department of Cardiology, Boston Children's Hospital, Boston, Massachusetts; Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts;
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Landzberg
authors.affiliation: Department of Pediatrics, Division of Cardiology, Medical College of Wisconsin, Milwaukee, Wisconsin;
authors.forename: Michael G
authors.initials: MG
authors.lastname: Earing
authors.affiliation: Department of Cardiology, Boston Children's Hospital, Boston, Massachusetts; Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts;
authors.forename: Fred M
authors.initials: FM
authors.lastname: Wu
authors.affiliation: Department of Cardiology, Boston Children's Hospital, Boston, Massachusetts;
authors.forename: John K
authors.initials: JK
authors.lastname: Triedman
authors.affiliation: Department of Medicine, Division of Respiratory Diseases, Boston Children's Hospital, Boston, Massachusetts; and.
authors.forename: Alicia
authors.initials: A
authors.lastname: Casey
authors.affiliation: Department of Medicine, Division of Respiratory Diseases, Boston Children's Hospital, Boston, Massachusetts; and.
authors.forename: Dawn A
authors.initials: DA
authors.lastname: Ericson
authors.affiliation: Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts;
authors.forename: David
authors.initials: D
authors.lastname: Systrom
authors.affiliation: Division of Cardiology, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Paridon
authors.affiliation: Department of Cardiology, Boston Children's Hospital, Boston, Massachusetts;
authors.forename: Jonathan
authors.initials: J
authors.lastname: Rhodes
mesh_terms: D000293:Adolescent; D002648:Child; D015444:Exercise; D005080:Exercise Test / Q000706:statistics & numerical data*; D017079:Exercise Tolerance; D005260:Female; D018729:Fontan Procedure / Q000009:adverse effects*; D006801:Humans; D008297:Male; D015995:Prevalence; D012120:Respiration Disorders / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology*; D013147:Spirometry / Q000706:statistics & numerical data*; D016896:Treatment Outcome; D014481:United States
keywords: Fontan procedure; congenital heart disease; exercise physiology; pulmonary; pulmonary heart disease