Key result
In patient-specific physical Fontan models, pulsatile flow resulted in a significantly different oscillatory shear index compared to steady flow (p=0.003).
Why the study?
Complications occur in Fontan patients due to abnormal blood flow dynamics, but in vivo physiological flow modulation and MRI resolution limitations hinder experimental investigation of factors impairing cardiovascular health.
Does pulsatile or high flow alter flow dynamics in patient-specific Fontan models compared to steady or low flow?
Does pulsatile or high flow alter flow dynamics in patient-specific Fontan models compared to steady or low flow?
p-value: p=0.003
In vitro patient-specific Fontan models demonstrate that pulsatile flow significantly alters oscillatory shear index compared to steady flow, and high-resolution PIV provides flow information unobtainable with 4D flow MRI alone.
Pulsatile flow may alter shear dynamics in Fontan circulation; leaves open need for in vivo validation before clinical modeling changes.
The Fontan procedure is a successful palliation for single ventricle defect. Yet, a number of complications still occur in Fontan patients due to abnormal blood flow dynamics, necessitating improved flow analysis and treatment methods. Phase-contrast magnetic resonance imaging (MRI) has emerged as a suitable method for such flow analysis. However, limitations on altering physiological blood flow conditions in the patient while in the MRI bore inhibit experimental investigation of a variety of factors that contribute to impaired cardiovascular health in these patients. Furthermore, resolution and flow regime limitations in phase contrast (PC) MRI pose a challenge for accurate and consistent flow characterization. In this study, patient-specific physical models were created based on nine Fontan geometries and MRI experiments mimicking low- and high-flow conditions, as well as steady and pulsatile flow, were conducted. Additionally, a particle image velocimetry (PIV)-compatible Fontan model was created and flow was analyzed with PIV, arterial spin labeling (ASL), and four-dimensional (4D) flow MRI. Differences, though nonstatistically significant, were observed between flow conditions and between patient-specific models. Large between-model variation supported the need for further improvement for patient-specific modeling on each unique Fontan anatomical configuration. Furthermore, high-resolution PIV and flow-tracking ASL data provided flow information that was not obtainable with 4D flow MRI alone.
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Rutkowski et al. (2019) studied Single ventricle defect with Fontan connection (n=9). Pulsatile flow and high flow conditions vs. Steady flow and low flow conditions was evaluated on Oscillatory shear index (p=0.003). In patient-specific physical Fontan models, pulsatile flow resulted in a significantly different oscillatory shear index compared to steady flow (p=0.003).
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