title: Functional status, heart rate, and rhythm abnormalities in 521 Fontan patients 6 to 18 years of age.
abstract: OBJECTIVE
  Our objective was to determine the relationship between functional outcome and abnormalities of heart rate and rhythm after the Fontan operation.
  
  
  METHODS
  The National Heart, Lung, and Blood Institute Pediatric Heart Network conducted a cross-sectional analysis of patients who had undergone a Fontan procedure at the 7 network centers. Analysis was based on 521 patients with an electrocardiogram (n = 509) and/or bicycle exercise test (n = 404). The Child Health Questionnaire parent report and the oxygen consumption at the anaerobic threshold were used as markers of functional outcome.
  
  
  RESULTS
  Various Fontan procedures had been performed: intracardiac lateral tunnel (59%), atriopulmonary connection (14%), extracardiac later tunnel (13%), and extracardiac conduit (11%). Prior volume unloading surgery was performed in 389 patients: bidirectional Glenn (70%) and hemi-Fontan (26%). A history of atrial tachycardia was noted in 9.6% of patients and 13.1% of patients had a pacemaker. Lower resting heart rate and higher peak heart rate were each weakly associated with better functional status, as defined by higher anaerobic threshold (R = -0.18, P = .004, and R = 0.16, P = .007, respectively) and higher Child Health scores for physical functioning (R = -0.18, P < .001, and R = 0.17, P = .002, respectively). Higher anaerobic threshold was also independently associated with younger age and an abnormal P-axis. Resting bradycardia was not associated with anaerobic threshold or Child Health scores.
  
  
  CONCLUSIONS
  In pediatric patients (6-18 years) after the Fontan procedure, a lower resting heart rate and a higher peak heart rate are each independently associated with better physical function as measured by anaerobic threshold and Child Health scores. However, these correlations are weak, suggesting that other, nonrhythm and nonrate, factors may have a greater impact on the functional outcome of pediatric patients after the Fontan operation.
authors.affiliation: Medical University of South Carolina, Charleston, SC, USA. Ablaufox@nshs.edu
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Blaufox
authors.forename: Lynn A
authors.initials: LA
authors.lastname: Sleeper
authors.forename: David J
authors.initials: DJ
authors.lastname: Bradley
authors.forename: Roger E
authors.initials: RE
authors.lastname: Breitbart
authors.forename: Allan
authors.initials: A
authors.lastname: Hordof
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Kanter
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Stephenson
authors.forename: Mario
authors.initials: M
authors.lastname: Stylianou
authors.forename: Victoria L
authors.initials: VL
authors.lastname: Vetter
authors.forename: J Philip
authors.initials: JP
authors.lastname: Saul
mesh_terms: D000293:Adolescent; D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use; D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control; D002648:Child; D003430:Cross-Sectional Studies; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D018729:Fontan Procedure / Q000706:statistics & numerical data*; D006304:Health Status; D006339:Heart Rate; D006801:Humans; D008297:Male; D010101:Oxygen Consumption; D011183:Postoperative Complications / Q000453:epidemiology*; D012086:Reoperation; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology; D016276:Ventricular Function
chemical_list: D000319:Adrenergic beta-Antagonists; D000889:Anti-Arrhythmia Agents