- Oral presentation
- Open Access
Respiratory pulsations affect fontan connection power loss: using real time velocity mapping to improve the accuracy of computational simulations
© Tang et al; licensee BioMed Central Ltd. 2015
- Published: 3 February 2015
- Computational Fluid Dynamic
- Pulsatility Index
- Average Flow Rate
- Flow Waveform
- Computational Fluid Dynamic Result
Total cavopulmonary connection (TCPC) hemodynamics has been hypothesized to be associated with long-term complications in single ventricle heart defect patients. Breath-holding or averaged free-breathing segmented phase contrast magnetic resonance imaging (PC-MRI) has been commonly used for the boundary conditions in numerical simulations to evaluate TCPC hemodynamics. However, the impact of ignoring respiration in the evaluation is not fully understood.
Nine patients with TCPC were included. Real-time PC-MRI images were acquired under resting free-breathing (FB) and breath-holding (BH) conditions at superior and inferior vena cava (SVC and IVC). Patient specific 3D TCPC anatomies were reconstructed from transverse CMR images. Computational fluid dynamics (CFD) simulations were performed using caval flow waveforms derived from real-time PC-MRI as inlet boundary conditions. A Windkessel three-element model was applied at the outlets to model the downstream vasculature. Average flow rates and pulsatility indices ([maximum-minimum]/average flow rate) under these two conditions throughout the duration of one respiratory cycle were compared. TCPC power loss was quantified and qualitative flow structure within the TCPC was compared between FB and BH conditions. Lagrangian particle tracking was performed for both conditions to quantify particle washout time.
Connection power loss of Patient 1 evaluated using FB and BH flow conditions
IVC vessel flow (L/min)
SVC vessel flow (L/min)
Average power loss (mW)
(i) Using time-averaged flow
(ii) Using pulsatile flow
% Increase from (i) to (ii)
Particle washout time*
Despite minimal impact on net flows, respiration has considerable impact on TCPC hemodynamics. Vessel flow waveforms acquired with FB condition have higher flow pulsatility. This translates into qualitative differences in flow structure within the connection, and increases in TCPC power loss. The importance of respiratory effects is highlighted, and potential error of calculation of energy dissipation by using BH acquisitions is demonstrated.
NIH R01 HL098252-01.
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