By Dr Haifa Abdul Latiff, National Heart Institute (IJN) Senior Consultant Paediatric Cardiologist
While pregnancy can be a relatively smooth journey for some women, there are instances when this is not the case especially when the unborn child detected to have structural defects or abnormality. These abnormalities are known as congenital anomalies.
The most common congenital anomaly is congenital heart defects.
National Heart Institute (IJN) Senior Consultant Paediatric Cardiologist Dr Haifa Abdul Latiff said about one in 100 babies are born with congenital heart disease (CHD). From this, two per cent of them have a critical lesion.
“Babies with critical heart defects may become very sick within 24 to 48 hours with difficulty in breathing or become severely blue,” she said.
“Without a timely lifesaving intervention, the baby may succumb or develop severe brain damage.” The congenital heart defects can be detected in-utero by a fetal echocardiogram.
What is fetal echocardiogram?
It is an ultrasound examination with a special probe to image the fetal heart. During the examination, the doctor will evaluate the fetal heart structures, function and heart rhythm.
“Although the fetal heart development completes around 11th week gestation, a good image of fetal heart can only be seen clearly around 18 to 20 weeks gestation using a good ultrasound machine,” she said.
“It should be performed by a trained maternal fetal specialist or a paediatric cardiologist.”
Advantages of having fetal echocardiogram
In most instances, fetal echocardiogram will detect the presence of congenital heart defect in the baby before he or she is born. This will allow the doctor to identify babies who may require a special attention after delivery.
These include anticipation and intervention of potential problems related to the heart defect and prevent serious complications to the baby, she added.
“It is also important to strategise the delivery plans,” she said. These include the location, timing and mode of delivery besides organising medical support that is needed after birth. “A joint collaboration with obstetricians, neonatologist and paediatric cardiologist can be organised before the baby is born.”
“An early referral and transfer of the baby to a cardiac centre for early intervention can be arranged whenever required.” She added another advantage of having fetal echocardiogram was the affected family can be counselled to help them understand the nature of the cardiac lesion and possible complications after birth.
“During the counselling sesson, the doctor will explain about the type and estimated timing treatment that might be required after birth. The outlook of the baby will also be discussed.
“This will help the parents to understand and prepare themselves mentally in taking care of a baby with CHD.”
She said that a fetal echocardiogram was also necessary in a condition where fetuses with a severe form of abnormal cardiac rhythm either when the fetal heart beat is too fast (more than 180/min) or too slow (less than 100/min). “Certain abnormal cardiac rhythm can be treated by giving medications to the mother.”
“Although catheter intervention can be performed in utero in some cardiac centres in developed countries, it is not widely available as it carries a high risk of fetal demise.”
Who should have fetal echocardiogram?
She added that ideally all pregnant mothers should have a detail baby scan to screen for a normal heart. However due to some constraints, in Malaysia only mothers with high risk of having a baby with CHD is referred for fetal echocardiogram.
These include mothers with diabetes, twin pregnancy, had in utero fertilisation, taken certain drugs (for example for epilepsy) or had high fever during the early trimester.
It also applies for those who have family members or close relatives with congenital heart disease or a fetus with chomosome or syndromic abnormality (for example Down’s sydrome) will also increase the risk of congenital heart defect.
Risks and frequency of test
Dr Haifa emphasised that the fetal echocardiogram was a very safe and risk free procedure. “It is non-invasive and does not involve radiation,” she said.
In terms of preparing for test, Dr Haifa said nothing special was required. “It would be helpful if the examination performed with full bladder. Mothers are advised to drink water and try to avoid passing urine just before the test.”
She added that the test should be repeated at least once between 32 and 36 weeks to assess the progress of the lesion for those with critical lesions that could potentially progress in utero. “For a simple lesion with no risk of progression in severity like a hole in the heart, a repeat test is not necessary.”
Limitations and challenges
She said that a fetal echocardiogram could be quite challenging as the fetus moves very frequently during examination. “The image of the fetus’s heart can be obscured by the fetal bony structures,” she added. “The quality of image may be poor in an obese mother.
The examination takes 30 minutes to one hour depending on the complexity of the cardiac lesion.” She added that fetal echocardiogram requires special skills and should only be performed by a trained maternal fetal specialist or a paediatrick cardiologist.
Right after the test, the patient together with their partner or family member will counselled about findings or result of examination. The expected type of treatment required, short and long-term outlook of the cardiac defect would be also discussed.
A written report of fetal echocardiogram findings as well as recommendations for delivery and post-delivery management will be given to the referring obstetrician.