# Four-Dimensional Flow in Fontan Patients: Advanced Haemodynamic Assessment

## TL;DR

This paper reviews how 4D Flow MRI helps assess blood flow in Fontan patients, improving understanding of their complex heart condition.

## Contribution

The paper provides a focused review on the application of 4D Flow MRI in Fontan physiology and its role in advanced hemodynamic assessment.

## Key findings

- 4D Flow MRI allows detailed 3D blood flow measurement in Fontan patients.
- The technique enables assessment of advanced hemodynamic parameters relevant to Fontan physiology.
- 4D Flow MRI is used for image-based simulations to better understand Fontan pathophysiology.

## Abstract

Staged palliation with the creation of a Fontan circulation is the standard surgical approach in patients with a single ventricle. The Fontan circulation is a complex circuit that is associated with various complications that may present early or later in life and can limit life quality and expectancy. In this context, a good understanding of the Fontan physiology is important to improve outcomes for single-ventricle patients. Cardiovascular magnetic resonance (CMR) is recommended for the long-term follow-up of Fontan patients, as it provides functional and haemodynamic information. Four-dimensional (4D) Flow MRI is a time-resolved, three-dimensional, velocity-encoded cardiovascular magnetic resonance technique that is increasingly used in Fontan patients because it not only enables measuring blood flow within a three-dimensional (3D) volume, but also allows for assessing more advanced haemodynamic parameters that may help in understanding the Fontan physiology and pathophysiology. Furthermore, 4D Flow is used for image-based simulations using computational fluid dynamics. In this review, we provide an overview of the use of cardiovascular magnetic resonance flow assessment, with a focus on four-dimensional flow (‘4D Flow’).