title: Ventricular afterload and ventricular work in fontan circulation: comparison with normal two-ventricle circulation and single-ventricle circulation with blalock-taussig shunts.
abstract: BACKGROUND
  Recent studies have indicated that there are inherent limitations associated with Fontan physiology. However, there have been no quantitative analyses of the effects of right heart bypass on ventricular afterload, hydraulic power, and resultant overall hemodynamics. Methods and Results- During routine cardiac catheterization, aortic impedance and ventricular hydraulic power were determined, both at rest and under increased ventricular work induced by dobutamine, in 17 patients with Fontan circulation, 15 patients with a single ventricle whose pulmonary circulation was maintained only by Blalock-Taussig shunts, and 13 patients who had normal 2-ventricle circulation. Both vascular resistance (nonpulsatile load on the ventricle) and pulsatile components of ventricular afterload (represented by low-frequency impedance) were significantly higher in the Fontan group than in the other groups (P<0.01), and this was associated with decreased cardiac output in the Fontan patients. In addition, hydraulic power cost per unit forward flow was 40% lower in the 2-ventricle circulation than in the single-ventricle circulation, suggesting lower ventricular efficiency in single-ventricle circulation attributable to the lack of a pulmonary ventricle. Furthermore, in the Fontan group, beta-adrenergic reserve was markedly decreased because of a limited preload reserve.
  
  
  CONCLUSIONS
  Fontan physiology is associated with disadvantageous ventricular power and afterload profiles and has limited ventricular reserve capacity. Thus, to improve the long-term prognosis of patients after Fontan surgery, future research should be conducted into medical interventions that can overcome these limitations inherent in Fontan circulation.
authors.affiliation: Department of Pediatric Cardiology, Saitama Medical School Hospital, Saitama, National Children's Hospital, Tokyo, 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: Jun
authors.initials: J
authors.lastname: Kobayashi
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: Shunei
authors.initials: S
authors.lastname: Kyo
authors.forename: Yuji
authors.initials: Y
authors.lastname: Yokote
authors.forename: Akira
authors.initials: A
authors.lastname: Ishizawa
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000714:Anastomosis, Surgical; D002307:Cardiography, Impedance; D002675:Child, Preschool; D003326:Coronary Circulation; D004280:Dobutamine / Q000494:pharmacology; D018729:Fontan Procedure; D006330:Heart Defects, Congenital / Q000503:physiopathology / Q000601:surgery*; D006352:Heart Ventricles / Q000503:physiopathology*; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D007700:Kinetics; D011652:Pulmonary Circulation; D011673:Pulsatile Flow; D014655:Vascular Resistance
chemical_list: D000318:Adrenergic beta-Agonists; D004280:Dobutamine