Congenital anomalies are the leading cause of infant death and congenital heart diseases accounts for 30 to 50 percent of these deaths. As the major cause of the largest single category of mortality, the identification and management of fetal cardiac abnormalities is of paramount importance. Population screening studies have shown that congenital heart disease occurs in 5/1000 to 8/1000 newborns, with about one-half causing major disease and one-half causing minor disease. Fetal echocardiography is a reasonably accurate investigation for the detection of such anomalies. The prospective parents, obstetricians and cardiologists should have some basic concepts about this extremely useful tool.
Indications for fetal echocardiography:
The common indications are divided into three categories: 1. familial 2.maternal 3.fetal. Each is elaborated below
1. Familial risk factors
●First or second degree relatives with congenital heart disease (eg, the fetus’ siblings, parents, and grandparents)
●Syndromes including congenital heart disease (eg, Noonan, tuberous sclerosis, Holt-Oram, velocardiofacial [DiGeorge] syndrome)
2. Maternal risk factors
●Maternal congenital heart disease
●Cardiac teratogen medications (e.g., lithium, methotrexate, thalidomide, drugs for seizure, isotretinoin, paroxetine, warfarin)
●Maternal medical illness (e.g., diabetes, phenylketonuria, anti Ro/SSA or anti La/SSB antibodies)
●Exposure to prostaglandin synthetase inhibitors (can cause premature closure of the ductus arteriosus in the third trimester)
●Rubella infection in the first trimester
●In vitro fertilization
3. Fetal risk factors
●Suspected cardiac anomaly during basic sonogram
●Abnormal fetal situs
●Increased nuchal translucency at 11 to 14 weeks of gestation
●Monochorionic twins, with or without twin-twin transfusion syndrome
What is the timing of fetal echocardiogram?
Usually between 18 to 22 weeks
How accurate is fetal echocardiography for detection of cardiac anomalies?
Studies suggest widely variable sensitivity of fetal echo ranging from 0 to 80%. A reasonable figure would be an accuracy of 40%.
How fetal echocardiography changes the outcome?
Any cardiac anomaly should be properly explained to the parents. Though parents are less interested to know the exact anatomical details of the cardiac problem. What is more important for them is the short-, mid- and long-term prognosis of the child. Also information about place of child birth, and method to be used like- normal labour, LSCS etc. Though fetal cardiac interventions have been tried , they are far from being of routine use in near future.
For doctors it is important to explain the prognosis in clear terms. One study showed that cardiac anomalies which were amenable to biventricular repair had better outcome than single ventricle physiology (Ultrasound Obstet Gynecol. 1997 Oct;10(4):237-41. PMID 9383873)
Referral to a maternal-fetal medicine specialist, pediatric cardiologist, geneticist, and/or neonatologist to discuss prognosis, obstetrical and neonatal management, and options is recommended.
The following interventions are recommended when a fetal cardiac anomaly is suspected:
•Full fetal echocardiography to evaluate cardiac structure and function, arterial and venous flow, and rhythm.
•Detailed scanning of the fetal anatomy to look for associated anomalies, particularly involving the digits and bones.
•Thorough family history to evaluate for familial abnormalities or syndromes.
•Thorough maternal medical history to identify chronic medical disorders, viral illnesses, or medications which are potential teratogens.
•Fetal karyotype, with screening for deletion in 22q11.2 when conotruncal anomalies are present
•Referral to a maternal-fetal medicine specialist, pediatric cardiologist, geneticist, and/or neonatologist to discuss prognosis, obstetrical and neonatal management, and options.
•Delivery at an institution that can provide neonatal cardiac care, if needed.
Dr. Anupam Jena