Respiratory Effects on Fontan Circulation During Rest and Exercise Using Real-Time Cardiac Magnetic Resonance Imaging

• Type of Material: Article
• Authors: Zhenglun Wei, Georgia Institute of Technology & Emory University; Kevin K. Whitehead, Georgia Institute of Technology & Emory University; Reza H. Khiabani, Children’s Hospital of Philadelphia; Michael Tree, Georgia Institute of Technology & Emory University; Elaine Tang, Georgia Institute of Technology & Emory University; Stephen M Paridon, Georgia Institute of Technology & Emory University; Mark A. Fogel, Children’s Hospital of Philadelphia; Ajit Yoganathan, Emory University
• Language: English
• Date: 2016-05-01
• Publisher: Elsevier
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2016 The Society of Thoracic Surgeons.
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1016/j.athoracsur.2015.11.011
• Title of Journal or Parent Work: Annals of Thoracic Surgery
• ISSN: 0003-4975
• Volume: 101
• Issue: 5
• Start Page: 1818
• End Page: 1826
• Grant/Funding Information: This study was supported by the National Heart, Lung, and Blood Institute Grants HL67622, HL098252, and HL089647.
• Keywords: SUBDIAPHRAGMATIC VENOUS HEMODYNAMICS; Cardiac & Cardiovascular Systems; Life Sciences & Biomedicine; FLOW; Cardiovascular System & Cardiology; Respiratory System; Surgery; TOTAL CAVOPULMONARY CONNECTION; Science & Technology
• Research Categories: Health Sciences, Medicine and Surgery; Health Sciences, Radiology

Abstract

Background It is known that respiration modulates cavopulmonary flows, but little data compare mean flows under breath-holding and free-breathing conditions to isolate the respiratory effects and effects of exercise on the respiratory modulation. Methods Real-time phase-contrast magnetic resonance combined with a novel method to track respiration on the same image acquisition was used to investigate respiratory effects on Fontan caval and aortic flows under breath-holding, free-breathing, and exercise conditions. Respiratory phasicity indices that were based on beat-averaged flow were used to quantify the respiratory effect. Results Flow during inspiration was substantially higher than expiration under the free-breathing and exercise conditions for both inferior vena cava (inspiration/expiration: 1.6 ± 0.5 and 1.8 ± 0.5, respectively) and superior vena cava (inspiration/expiration: 1.9 ± 0.6 and 2.6 ± 2.0, respectively). Changes from rest to exercise in the respiratory phasicity index for these vessels further showed the impact of respiration. Total systemic venous flow showed no significant statistical difference between the breath-holding and free-breathing conditions. In addition, no substantial difference was found between the descending aorta and inferior vena cava mean flows under either resting or exercise conditions. Conclusions This study demonstrated that inferior vena cava and superior vena cava flow time variance is dominated by respiratory effects, which can be detected by the respiratory phasicity index. However, the minimal respiration influence on net flow validates the routine use of breath-holding techniques to measure mean flows in Fontan patients. Moreover, the mean flows in the inferior vena cava and descending aorta are interchangeable.