title: Cardiac rest and reserve function in patients with Fontan circulation.
abstract: OBJECTIVE
  In the present study, we systematically tested cardiac rest and reserve function in patients with Fontan physiology to check for inherent limitations of this circulation.
  
  
  BACKGROUND
  Details of the mechanisms of cardiac performance that could account for adverse outcome after Fontan surgery are not well understood.
  
  
  METHODS
  The subjects were 17 Fontan patients with good functional status (Fontan group) and 20 patients with normal two-ventricle circulation (control group). We examined baseline ventricular contractility, diastolic function, and loading factors, and examined changes in those parameters in response to increased heart rate (HR) due to atrial pacing and in response to beta-adrenergic stimulation, using ventricular pressure-area relationships during preload reduction.
  
  
  RESULTS
  At baseline, the Fontan patients exhibited minimal abnormality of cardiac properties, but the significant increase in afterload resulted in decreased cardiac index. In addition, Fontan circulation was associated with limited inotropic response and worsening of diastolic filling with increased HR, leading to decreased systolic pressure and elevation of central venous pressure at higher HRs (p < 0.05 vs. control). Furthermore, beta-adrenergic reserve was markedly decreased in the Fontan group, compared with controls, owing to limited preload reserve rather than limited contractile reserve.
  
  
  CONCLUSIONS
  Because normal ventricular-vascular interaction and augmentation of cardiac performance during increased HR and adrenergic stimulation are important for maintaining cardiac output and exercise capacity, the present results may have important implications for the mechanisms underlying adverse outcome after Fontan surgery. Thus, improvement of long-term prognosis of patients after Fontan surgery requires the development of medical interventions that can overcome such limitations inherent in Fontan circulation.
authors.affiliation: Department of Pediatric Cardiology and Cardiovascular Surgery, Saitama Medical School Hospital, Iruma-Gun, Saitama, Japan. hsenzaki@saitama-med.ac.jp
authors.forename: Hideaki
authors.initials: H
authors.lastname: Senzaki
authors.forename: Satoshi
authors.initials: S
authors.lastname: Masutani
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Ishido
authors.forename: Mio
authors.initials: M
authors.lastname: Taketazu
authors.forename: Toshiki
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Nozomu
authors.initials: N
authors.lastname: Sasaki
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Asano
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Katogi
authors.forename: Shunei
authors.initials: S
authors.lastname: Kyo
authors.forename: Yuji
authors.initials: Y
authors.lastname: Yokote
mesh_terms: D002648:Child; D003326:Coronary Circulation; D018729:Fontan Procedure; D006321:Heart / Q000502:physiology*; D006339:Heart Rate; D006801:Humans