A Personal Account
Some people live their whole lives not knowing they carry the genetic mutation for Long QT syndrome (LQT). Others discover they have inherited this genetic mutation after they or one of their family members have symptoms of fainting spells, seizures, or cardiac arrest. For KC, a 28 year old woman, the diagnosis came as a surprise: She had no previous knowledge of LQTS prior to her diagnosis 10 years ago. Yes, she had a history of seizures for which she was being treated, but it wasn’t until age 18, that she had two cardiac arrests and was found to have a prolonged QT interval on ECG. She spent multiple days in a coma, and underwent placement of a defibrillator. Genetic testing was not available at that time, so her specific LQTS mutation was not known. In addition, she was adopted, so she was unaware if anyone else in her family also had LQTS.
For the next 10 years she was treated with metoprolol and did well. Then she became pregnant with her first child. Knowing the risk was 50%, she feared her child would also have LQTS. She was told there was no way of knowing until the child was born, so very little additional testing was conducted. Happily, her son, who was born at term, was not affected.
Fast forward two years: KC became pregnant a second time, this time with a girl. Unlike with her first pregnancy, this time she was evaluated by a perinatal cardiologist who specialized in fetal arrhythmias. During her monthly fetal echocardiograms, it was noted that the fetal heart rates was somewhat slower than normal. However, no other arrhythmias were found. Because the fetus had a 50% risk of long QT syndrome, at the suggestion of the perinatal cardiologist, KC agreed to undergo a fetal magnetocardiogram: a non-invasive test assessing fetal heart rhythms and conduction (pictured below, right). There are only a few centers in the country that perform fetal magnetocardiography: one is Madison, Wisconsin.
An fMCG utilizes a biomagnetometer known as a Superconducting Quantum Interference Device, or SQUID that resides in a magnetically shielded room the size of a large closet (see photo). The test causes no distress to the mother or the fetus, and also involves an ultrasound machine to locate the position of the fetus and an electrocardiogram (ECG) attached to the mother’s abdomen and thighs. The biomagnetometer is positioned over the mother’s abdomen. The entire process took about two hours and as stated by KC, “the only difficult part of the whole fMCG experience was the drive to Madison”!
The results of the magnetocardiogram were critical to the next 8 weeks of the pregnancy, as the fMCG detected not only a very prolonged QT interval, but several unexpected and short episodes of Torsades de pointes (TdP) that had not been seen during multiple fetal echocardiograms. It was hard for KC to receive the news, but she concentrated on the positive: Long QT syndrome had been diagnosed before any harm had come to her fetus, and her birth and postnatal care could be planned. The beta adrenergic blocking agent she was taking was changed to propranolol, and she was given high dose magnesium. Both crossed the placenta to help to treat Torsades in her daughter.
In early June, at 39 weeks of gestation, KC happily welcomed her baby girl. Because her daughter’s TdP was controlled by the medications she was taking, KC did not need a cesarean-section delivery. Her daughter was immediately started on medication, and after an early brief run of TdP, did very well. Genetic testing has confirmed that mother and daughter shared the same LQT 2 mutation.
After almost 2 months of close monitoring in the Neonatal Intensive Care Unit, KC’s daughter is ready to come home. She will be on medications, and an external defibrillator will be close by. Almost daily, KC thinks about the potential arrhythmias that may affect her daughter. However, she does not live her life in fear; instead, she focuses on educating those around her about LQTS. She feels that with timely diagnosis and treatment the outcome of LQTS can be improved both before and after birth.
Carolyn A. Sullivan, MSN, AC-PNP
Perinatal Cardiology Coordinator
Advocate Heart Institute for Children