The importance of the muscle and ventilatory blood pumps during exercise in patients without a subpulmonary ventricle (fontan operation)

Keri M. Shafer, Jorge A. Garcia, Tony G Babb, David E Fixler, Colby R. Ayers, Benjamin D Levine

Research output: Contribution to journalArticle

53 Scopus citations

Abstract

Objectives: The aim of this study was to determine the relative contribution of the muscle and ventilatory pumps to stroke volume in patients without a subpulmonic ventricle. Background: In patients with Fontan circulation, it is unclear how venous return is augmented to increase stroke volume and cardiac output during exercise. Methods: Cardiac output (acetylene rebreathing), heart rate (electrocardiography), oxygen uptake (Douglas bag technique), and ventilation were measured in 9 patients age 15.8 ± 6 years at 6.1 ± 1.8 years after Fontan operation and 8 matched controls. Data were obtained at rest, after 3 min of steady-state exercise (Ex) on a cycle ergometer at 50% of individual working capacity, during unloaded cycling at 0 W (muscle pump alone), during unloaded cycling with isocapnic hyperpnea (muscle and ventilatory pump), during Ex plus an inspiratory load of 12.8 ± 1.5 cm water, and during Ex plus an expiratory load of 12.8 ± 1.6 cm water. Results: In Fontan patients, the largest increases in stroke volume and stroke volume index were during zero-resistance cycling. An additional increase with submaximal exercise occurred in controls only. During Ex plus expiratory load, stroke volume indexes were reduced to baseline, non-exercise levels in Fontan patients, without significant changes in controls. Conclusions: With Fontan circulation increases in cardiac output and stroke volume during Ex were due to the muscle pump, with a small additional contribution by the ventilatory pump. An increase in intrathoracic pressure played a deleterious role in Fontan circulation by decreasing systemic venous return and stroke volume.

Original languageEnglish (US)
Pages (from-to)2115-2121
Number of pages7
JournalJournal of the American College of Cardiology
Volume60
Issue number20
DOIs
StatePublished - Nov 13 2012

Keywords

  • Fontan
  • cardiac output
  • exercise physiology
  • muscle pump
  • ventilatory pump

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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