Document Detail

Mechanisms of systemic adaptation to univentricular Fontan conversion.
MedLine Citation:
PMID:  20483432     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: After univentricular Fontan conversion, systemic venous pressure serves as the sole driving force for transpulmonary blood flow. Consequently, systemic venous return is markedly altered and ventricular filling is subnormal. The mechanisms and time course of systemic adaptation to Fontan conversion are incompletely understood. We hypothesized that acute elevation in systemic venous pressure induces an adaptive response similar to conversion to a univentricular Fontan circulation.
METHODS: Adjustable vessel occluders were placed around the superior and inferior vena cavae in juvenile sheep. After 1-week recovery, occluders were tightened to acutely increase and maintain systemic venous pressure at 15 mm Hg (n = 6), simulating 1-stage Fontan conversion. Control animals (n = 4) received identical surgery, but venous pressure was not manipulated.
RESULTS: Cardiac index decreased significantly (3.9 ± 1.0 mL/min/m(2) to 2.7 ± 0.7 mL/min/m(2), P < .001) and then normalized to control at 2 weeks. Circulating blood volume increased (100 ± 9.4 mL/kg vs 85.5 ± 8.4 mL/kg, P = .034) as a persistent response. Cardiac reserve improved and was not different from control by week 3. Resting heart rate decreased in both groups. Oxygen extraction (arteriovenous oxygen difference) and neurohormonal mediators increased transiently and then normalized by week 2.
CONCLUSIONS: Adaptation to global elevation in systemic venous pressure to Fontan levels is complete within 2 weeks. Increased blood volume and reduced heart rate are persistent responses. Increased oxygen extraction and neurohormonal up-regulation are temporary responses that normalize with recovery of cardiac output. With improved physiologic understanding of systemic adaptation to Fontan conversion, approaches to single-ventricle palliation can be more objectively assessed and optimized.
Cynthia D Myers; Kimberly Ballman; Lindsay E Riegle; Kelly D Mattix; Kenneth Litwak; Mark D Rodefeld
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2010-05-18
Journal Detail:
Title:  The Journal of thoracic and cardiovascular surgery     Volume:  140     ISSN:  1097-685X     ISO Abbreviation:  J. Thorac. Cardiovasc. Surg.     Publication Date:  2010 Oct 
Date Detail:
Created Date:  2010-09-20     Completed Date:  2010-10-11     Revised Date:  2013-05-29    
Medline Journal Info:
Nlm Unique ID:  0376343     Medline TA:  J Thorac Cardiovasc Surg     Country:  United States    
Other Details:
Languages:  eng     Pagination:  850-6, 856.e1-6     Citation Subset:  AIM; IM    
Copyright Information:
Copyright © 2010 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.
Department of Surgery, Section of Cardiothoracic Surgery, the James Whitcomb Riley Hospital for Children, Indiana University School of Medicine, Indianapolis, Ind, USA.
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MeSH Terms
Adaptation, Physiological
Blood Volume
Cardiac Output
Fontan Procedure*
Heart Rate
Heart Ventricles / physiopathology*
Hormones / blood
Time Factors
Venous Pressure*
Ventricular Function*
Grant Support
Reg. No./Substance:

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