Prenatal diagnosis of a long QT syndrome by fetal magnetocardiography in an unshielded bedside environment.

OBJECTIVE

The potentially life threatening long QT syndrome should be diagnosed during pregnancy to improve perinatal care.

METHODS

A patient with a family history for a hereditary long QT syndrome presented at 30 weeks of her first pregnancy with fetal bradycardia and a narrow oscillation bandwidth on cardiotocography without structural abnormalities of the fetal heart. Fetal magnetocardiography was performed with a prototype biomagnetometer/gradiometer device in a magnetically unshielded environment. The cardiac time intervals were determined in the averaged PQRST complex.

RESULTS

The QT time and the frequency-corrected QTc showed a marked prolongation to 380 ms and 0.52 s, respectively. The findings were confirmed in the postnatal electrocardiogram after spontaneous term delivery in a perinatal center. The causative mutation on chromosome 11 had been passed on to the newborn from his mother.

CONCLUSION

Bedside fetal magnetocardiography revealed the exact diagnosis of the long QT syndrome in a period of the gestation when the fetus was electrically isolated by the vernix caseosa that hinders electrocardiography. To patients at risk of fetal cardiac abnormalities, magnetocardiography can be offered as a non-invasive diagnostic bedside procedure. The diagnosis should trigger closer surveillance and delivery in a perinatal center.