Foetal heart monitor uses magnetism to identify abnormal heart
14 November 2013
A device that records the natural magnetic activity of the heart
of foetuses can help identify abnormal heart rhythms in unborn
It was used in a study to document the electrical aspects of a
condition called 'long QT syndrome' in the womb, which is a common
cause of sudden death in infants and stillbirth.
The research has been published in the American Heart Association
The study is the first to document the electrophysiological
characteristics of foetal long QT syndrome and to evaluate the
diagnostic accuracy of the magnetic EKG, or magnetocardiogram, in a
sizable population of at-risk foetuses.
“Until now, physicians were unable to diagnose a serious heart
condition known as long QT syndrome until after birth,” said Ronald
T. Wakai, PhD, principal investigator of the study and a professor
of medical physics at the University of Wisconsin School of Medicine
and Public Health in Madison.
“Our study shows that you can diagnose
the condition in utero and identify which foetuses are most likely
to have life-threatening arrhythmia. We also showed that once
detected the arrhythmia can be effectively treated in utero.”
Long QT syndrome is present in about one in every 2,000 births
and accounts for about 10% of sudden infant deaths and
unexplained stillbirths, Wakai said. It’s also a leading cause of
sudden death in children and young adults. Long QT predisposes the
heart to develop a potentially lethal heart rhythm, but foetuses can
be successfully treated if the rhythm is identified.
Using the magnetic EKG, the researchers diagnosed long QT in the
womb with 89% accuracy.
The researchers evaluated 30 pregnancies in 1996-2012 in
Wisconsin and at two locations in Japan. They chose patients based
on a family history of long QT syndrome, unexplained death of a
sibling in infancy or childhood, or a suspicious foetal heart
rhythm. They then collected data positioning a probe on the mother’s
abdomen as early as midway through the pregnancy.
Long QT syndrome was diagnosed in 21 of the foetuses. Six of the
foetuses had dangerous heart rhythms and one was delivered early
after ominous rhythms were noted.
Magnetic EKGs will be put into practical use in the
“not-too-distant future,” but an accurate and complete family
history remains the most critical aspect of diagnosing long QT
syndrome, Wakai said.
Ronald T. Wakai, Ph.D et al, In Utero Diagnosis of Long QT
Syndrome by Magnetocardiography. Circulation. DOI: