Article Text
Abstract
Objectives Although a life-preserving surgery for children with single ventricle physiology, the Fontan palliation is associated with striking morbidity and mortality with advancing age. Our primary objective was to evaluate the impact of non-invasive, external, thoraco-abdominal ventilation on pulmonary blood flow (PBF) and cardiac output (CO) as measured by cardiovascular magnetic resonance (CMR) imaging in adult Fontan subjects.
Methods Adults with a dominant left ventricle post-Fontan palliation (lateral tunnel or extracardiac connections) and healthy controls matched by sex and age were studied. We evaluated vascular flows using phase-contrast CMR imaging during unassisted breathing, negative pressure ventilation (NPV) and biphasic ventilation (BPV). Measurements were made within target vessels (aorta, pulmonary arteries, vena cavae and Fontan circuit) at baseline and during each ventilation mode.
Results Ten Fontan subjects (50% male, 24.5 years (IQR 20.8–34.0)) and 10 matched controls were studied. Changes in PBF and CO, respectively, were greater following BPV as compared with NPV. In subjects during NPV, PBF increased by 8% (Δ0.20 L/min/m2 (0.10–0.53), p=0.011) while CO did not change significantly (Δ0.17 L/min/m2 (−0.11–0.23), p=0.432); during BPV, PBF increased by 25% (Δ0.61 L/min/m2 (0.20–0.84), p=0.002) and CO increased by 16% (Δ0.47 L/min/m2 (0.21–0.71), p=0.010). Following BPV, change in PBF and CO were both significantly higher in subjects versus controls (0.61 L/min/m2 (0.2–0.84) vs −0.27 L/min/m2 (−0.55–0.13), p=0.001; and 0.47 L/min/m2 (0.21–0.71) vs 0.07 L/min/m2 (−0.47–0.33), p=0.034, respectively).
Conclusion External ventilation acutely augments PBF and CO in adult Fontan subjects. Confirmation of these findings in larger populations with longer duration of ventilation and extended follow-up will be required to determine sustainability of haemodynamic effects.
- advanced cardiac imaging
- cardiac imaging and diagnostics
- cardiac magnetic resonance (CMR) imaging
- congenital heart disease surgery
- Fontan physiology
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Footnotes
Twitter @charla789, @DrRachelWald
PC and GRK contributed equally.
Contributors PC and RW were responsible for conception, design of the study and obtaining funding. PC, GRK and S-JY contributed to subject recruitment and data acquisition. GRK analysed the CMR studies. KY and KH contributed to statistical analysis. All authors made substantial contributions to analysis and interpretation of data. PC, GRK and RW drafted the manuscript. All authors critically revised and reviewed the manuscript. All authors read and approved the final manuscript. PC, GRK and RW agreed to be responsible for the overall content as guarantors. The corresponding author has the right to grant on behalf of all authors and does grant on behalf of all authors, an exclusive licence (or non-exclusive for government employees) on a worldwide basis to the BMJ Publishing Group Ltd (BMJPGL) and its licensees to permit this article (if accepted) to be published in Heart editions and any other BMJPGL products to exploit all subsidiary rights.
Funding PC and RW were recipients of grant support from the Peter Munk Cardiac Centre Innovation Committee.
Competing interests None declared.
Patient and public involvement Patients and/or the public were not involved in the design, conduct, reporting or dissemination plans of this research.
Patient consent for publication Not required.
Ethics approval This prospective study received approval from institutional research ethics boards (Toronto General Hospital and SickKids) as well as Health Canada.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available on reasonable request.