Validation of echocardiographic features in foetuses

The congenital long-QT syndrome (LQTS) is an inheritable cardiac arrhythmia
disorder and is associated with sudden cardiac death (SCD) due to malignant
ventricular arrhythmias. When LQTS presents in utero or during the first week
of life, the prognosis may be poor. Timely appropriate therapy can manage
foetal arrhythmias and reverse foetal heart failure and thus early diagnosis
may be lifesaving even in the perinatal period. The foetal echocardiogram is
the main diagnostic tool for evaluating foetal arrhythmias providing accurate
information about the atrial and ventricular contractions that indirectly
reflect the P-wave and QRS-complex. Currently echocardiography cannot assess a
derivative of the QT-interval. In order to improve the role of the foetal
echocardiogram in the diagnosis of LQTS, mechanical parameters that
theoretically would be the correlation of the cardiac repolarization have been
studied. Mechanical abnormalities in the contraction and relaxation pattern in
adult and paediatric LQTS-patients were found and could be used for the
diagnosis and risk-stratification in LQTS. These abnormalities can be detected
with echocardiographic Doppler tracings and colour Tissue Doppler Imaging
(cTDI). Follow up studies found that LVIRT and the myocardial contraction
duration were prolonged in LQTS-foetuses and had a high distinctive character
for the diagnosis of LQTS and a strong correlation with the QT-interval.
However, establishment of normal ranges of the LVIRT and myocardial contraction
duration in healthy foetuses is needed. Furthermore, these previous results
should be validated in a larger cohort of LQTS foetuses.

To establish normal reference values for the foetal LVIRT and myocardial
contraction duration using respectively echocardiographic Doppler tracings and
cTDI at a foetal age around 20, 28 and 30 weeks* gestation. These reference
values will be compared with foetuses with postnatally confirmed LQTS.

This is a prospective observational cohort study.

In this echocardiogram Doppler tracings and cTDI recordings will be obtained
around week 20, 28 and 30 weeks* gestation. In order to do this, patients will
be asked to come to the Academic Medical Center in Amsterdam for three
additional times. This study does not have an advantage for the participating
patients. However, these additional examinations will be performed by a
paediatric cardiologist who will first confirm that the foetus has a normal
heart. This knowledge could be of emotional benefit to the mother. Should an
abnormality be detected the normal management of that problem will be
initiated. Women who are pregnant with a foetus with a 50% risk of LQTS will be
asked to come to the hospital for two extra visits.