Four dimensional flow analysis of complex congenital heart disease

In children born with a transposition of the great arteries the aorta arises
from the morphologic right ventricle and the pulmonary artery arises from the
morphologic left ventricle. The right ventricle pumps oxygen-poor blood from
the body into the aorta and to the rest of the body, while the left ventricle
pumps oxygen-rich blood coming from the lungs back into the pulmonary artery
and to the lungs. This means that, apart from the lungs, there is no supply of
oxygen-rich blood to any other organ in the body.

With an arterial switch operation the aorta and pulmonary artery are connected
to the 'correct' ventricles. This surgical technique has been performed in
Utrecht since 1977. The surgery greatly improves the survival of patients with
a transposition of the great arteries. Nonetheless, as they grow older, many
patients experience complications. The most common being narrowing of the
pulmonary artery and its branches. Often (re)intervention is required. The
different underlying pathophysiological processes of these complications is
known, However, the effects on the right ventricular function, exercise
capacity and lung capicity are still unknown.

The novel, four-dimensional flow cardiac magnetic resonance (4D-flow CMR)
technique allows for a more comprehensive evaluation of the pulmonary artery
flow, including the site of possible stenosis. 4D Flow CMR provides a
non-invasive method for the qualitative and quantitative characterization of
blood flow and can be used to derive advanced hemodynamic measures without
radiation burden.

We want to qualify and quantify the blood flow in the arterial switch
circulation using 4D-flow CMR and investigate whether there is a relationship
between abnormal blood flow and clinical outcomes such as right ventricular
function, lung function, and exercise capacity.

To determine whether 4D-flow CMR volume measurements are superior to 2D-PC CMR
volume measurements by comparing the intra-class correlation between 2D-PC flow
CMR stroke volume measurements in the MPA and multi-slice volumetric RV flow
volume to the intra-class correlation between 4D-flow CMR stroke volume
measurements in the MPA to multi-slice volumetric RV flow volume.

The secondary objective is to explore the predictive value of 4D-flow
measurements for clinical outcomes such as right ventricular function, exercise
capacity and lung function.

A cross-sectional observational study

Participants < 16 years of age:
All diagnostic tests that will be performed are regular follow up
investigations. 4D-flow and exercise measurements during CMR are done purely
for research purposes. The extra MRI measurements will extend the CMR duration
with approximately 10-15 minutes . We will try to plan all three tests on one
day.

Participants > 16 years of age:
The echocardiography will be performed as a regular follow up investigation.
The CMR and cardiopulmonary exercise test can be performed solely for the
study. Both the CMR and the cardiopulmonary exercise test have a duration of
approximately one hour. We will plan these investigations on one day, to
minimize patient burden. The 4D-flow CMR measurements have no additional risk.
The risk of an adverse reaction to the CMR contrast is irrelevant for the
study, since administration of contrast will only be done if the treating
clinician orders it and not for study purposes. In very rare cases, ventricular
tachycardia can develop during cardiopulmonary exercise testing.