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Human Fetal Blood Flow Quantification with Magnetic Resonance Imaging and Motion Compensation
Published on: January 7, 2021
Magnetic Resonance Imaging Assessment of Blood Flow Distribution in Fenestrated and Completed Fontan Circulation with
Pablo Caro-Dominguez1, Rajiv Chaturvedi2, Govind Chavhan1
1Department of Diagnostic Imaging, The Hospital for Sick Children, University of Toronto, Toronto, Canada.
Insights
Magnetic resonance imaging (MRI) reveals reduced abdominal flow in patients with Fontan circulation. This is linked to decreased cardiac output or collateral diversion, impacting organ perfusion.
Area of Science:
- Cardiovascular Imaging
- Pediatric Cardiology
- Hemodynamics
Background:
- Fontan circulation is a complex surgical palliation for single-ventricle congenital heart defects.
- Understanding regional blood flow distribution is crucial for managing patients with Fontan physiology.
- Previous studies have not fully elucidated the detailed flow patterns in different Fontan configurations.
Purpose of the Study:
- To investigate and characterize regional blood flow distribution in children with Fontan circulation using magnetic resonance imaging (MRI).
- To compare flow volumes in thoracic and abdominal arteries and veins against healthy controls.
- To identify factors contributing to altered flow patterns in different Fontan types.
Main Methods:
- Retrospective analysis of MRI data from 39 children with Fontan circulation.
- Patients categorized into fenestrated (Group 1) and completed (Groups 2 & 3) Fontan circulation groups, with variations in anesthesia use.
- Flow volumes measured across major thoracic and abdominal vessels and compared to reference ranges from healthy individuals.
Main Results:
- Reduced abdominal flow was observed in both fenestrated and completed Fontan groups compared to controls.
- Fenestrated Fontan circulation (Group 1) showed normal cardiac output but flow diversion to aortopulmonary collaterals.
- Completed Fontan circulation (Group 3) demonstrated decreased cardiac output and significantly reduced superior mesenteric and portal venous flows.
Conclusions:
- Fontan circulation is associated with significantly reduced abdominal blood flow.
- Altered flow dynamics in Fontan patients stem from either reduced cardiac output and portal venous return or diversion of flow to collateral vessels.
- These findings highlight the hemodynamic challenges in Fontan physiology and the need for tailored management strategies.
Objective:
To investigate the regional flow distribution in patients with Fontan circulation by using magnetic resonance imaging (MRI).
Materials And Methods:
We identified 39 children (18 females and 21 males; mean age, 9.3 years; age range, 3.3-17.0 years) with Fontan circulation in whom flow volumes across the thoracic and abdominal arteries and veins were measured by using MRI. The patients were divided into three groups: fenestrated Fontan circulation group with MRI performed under general anesthesia (GA) (Group 1, 15 patients; average age, 5.9 years), completed Fontan circulation group with MRI performed under GA (Group 2, 6 patients; average age, 8.7 years), and completed Fontan circulation group with MRI performed without GA (Group 3, 18 patients; average age, 12.5 years). The patient data were compared with the reference ranges in healthy controls.
Results:
In comparison with the controls, Group 1 showed normal cardiac output (3.92 ± 0.40 vs. 3.72 ± 0.69 L/min/m², p = 0.30), while Group 3 showed decreased cardiac output (3.24 ± 0.71 vs. 3.96 ± 0.64 L/min/m², p = 0.003). Groups 1 and 3 showed reduced abdominal flow (1.21 ± 0.28 vs. 2.37 ± 0.45 L/min/m², p < 0.001 and 1.89 ± 0.39 vs. 2.64 ± 0.38 L/min/m², p < 0.001, respectively), which was mainly due to the diversion of the cardiac output to the aortopulmonary collaterals in Group 1 and the reduced cardiac output in Group 3. Superior mesenteric and portal venous flows were more severely reduced in Group 3 than in Group 1 (ratios between the flow volumes of the patients and healthy controls was 0.26 and 0.37 in Group 3 and 0.63 and 0.53 in Group 1, respectively). Hepatic arterial flow was decreased in Group 1 (0.11 ± 0.22 vs. 0.34 ± 0.38 L/min/m², p = 0.04) and markedly increased in Group 3 (0.38 ± 0.22 vs. -0.08 ± 0.29 L/min/m², p < 0.0001). Group 2 showed a mixture of the patterns seen in Groups 1 and 3.
Conclusion:
Fontan circulation is associated with reduced abdominal flow, which can be attributed to reduced cardiac output and portal venous return in completed Fontan circulation, and diversion of the cardiac output to the aortopulmonary collaterals in fenestrated Fontan circulation.
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