COMMON STRUCTURAL ABNORMALITIES / FETAL ABNORMALITIES

TETRALOGY OF FALLOT

Tetralogy of fallot is one of the most common forms of cyanotic congenital heart disease and is found in about 1 in 3600 live births and accounts for 3% to 7% of infants with congenital heart disease. It associated with some of the cardiac abnormalities, such as tight sided aortic arch, patent foramen ovale and left superior vena cava. It is also associated with chromosomal abnormalities with the rate of 30% of tetralogy of fallot cases.

EBSTEIN SYNDROME

Ebstein anomaly is a rare heart defect that's present at birth. Ebstein anomaly is the abnormality on the tricuspid valve of the heart caused to the “atrialized” portion of the right ventricle formed. It is associated with obstruction of the right ventricular outflow tract and atria septal defects. The prognosis is poor.

DOUBLE OUTLET RIGHT VENTRICLE

Double outlet right ventricle is a type of ventriculoarterial connection in which both great vessels arise either entirely or predominantly from the right ventricle. It is associated with pulmonary stenosis, pulmonary stenosis, transposition of the great arteries. Another heart condition, ventricular septal defect (VSD), always occurs with double outlet right ventricle. This is a hole in the tissue wall (septum) that normally separates the right and left ventricles. The prognosis is generally poor.

TRANSPOSITION OF GREAT ARTERIES

Transposition of the great arteries is a serious but rare heart, in which the two main arteries leaving the heart are reversed (transposed). Although some factors, such as genetics, rubella or other viral illnesses during pregnancy, maternal age over 40, or maternal diabetes, may increase the risk of this condition, in most cases the cause is unknown. There are 2 types of TGA. Complete transposition of the great arteries (D-TGA) and congenitally corrected transposition of the great arteries (cc-TGA). This is a common cardiac malformation with atrioventricular concordance and ventriculoarterial discordance. VSDs and pulmonary stenosis are the two most common associated cardiac findings with D-TGA. Transposition of the great arteries is usually detected either prenatally or within the first hours to weeks of life.

EDWARDS SYNDROME

Edward syndrome is also called as Trisomy 18. It is a genetic disorder in babies that causes severe disability which is caused by the presence of a third copy of all or part of chromosome 18. It occurs in around 1 in 3,000 to 5,000 live births. Babies born with condition usually do not survive for much longer than a week. Only 5 to10% of babies born with trisomy 18 live past their first birthday, and they often have severe mental disabilities. Edwards syndrome is much more common in female. Babies with Edwards syndrome will have low birth weight, small head and jaw, an unusual-looking face and head, unusual hands and feet with overlapping fingers and webbed toes, problems with feeding, breathing, seeing and hearing. It can be associated with heart defects (eg. Ventricular septal defect, tetralogy of Fallot and Double outlet right ventricle), musculoskeletal anomalies, urinary tract anomalies and brain anomalies (eg. Dandy-walker syndrome, holoprosencephaly).

DOWN SYNDROME

Down syndrome is also called as Trisomy 21. It is a genetic disorder in babied that causes mild to serious physical and mental developmental delays and disabilities which is caused by the presence of an extra copy of their 21st chromosome. This extra chromosome causes problems as the brain and physical features develop. It occurred about 1 in 1000 - 1100 live births. Ultrasound finding will show thicken nuchal translucency in the 1st trimester. Soft markers associated with Down syndrome which can be seen at 1st trimester are absent nasal bone, abnormal ductus venosus flow and abnormal tricuspid flow. Soft markers associated with Down syndrome which can be see at 2nd trimester are increase nuchal fold thickness, absent or hypoplastic nasal bone, short femur and humer, echogenic bowel, intracardiac echogenic foci, mild renal pelvis dilatation and mild ventriculomegaly. Major abnormalities associated with Down syndrome are cardiac defects (eg, Atrioventricular septal defect, Ventricular septal defect and Tetralogy of Fallot), gastrointestinal anomalies(eg. Duodenal atresia, esophageal atresia and omphalocele). Down syndrome can have many effects, and it’s different for each person. Babies with Down syndrome tend to have certain physical features in common, eg. Small ears, flat nose, short neck, eyes slant up at the outer corner, protruding tongue.

PATAU SYNDROME

Patau syndrome is also called as trisomy 13. It is a syndrome caused by a chromosomal abnormality, in which three copies of chromosome 13 in each cell in the body instead of the usual two copies. It happens when cells divide abnormally during reproduction, and create extra genetic material on chromosome 13. The extra genetic material disrupts the normal course of development, causing the characteristic features of trisomy 13 for severe mental and physical problems. The incidence of trisomy 13 is about 1 in 16,000 newborns. Most babies born with it don’t live past their first month or year. But some can survive for years. This syndrome is a chromosomal condition associated with severe intellectual disability and physical abnormalities in many parts of the body. Babies born with trisomy 13 often have a low birthweight, brain-structure problems, and it can affect their facial development as well. Other birth defects of Patau syndrome include cleft lip and palate, polydactyly, clenched hands, low-set ears and small head.

HOLOPROSENCEPHALY

Holoprosencephaly is an abnormality of brain development in which the brain doesn't properly divide into the right and left hemispheres. The incidence of holoprosencephaly is 1 in 1,300 fetuses at 12 weeks’ gestation and 1 in 10,000 births. There are 4 types of holoprosencephaly: alobar, semilobar, lobar and syntelencephaly. Alobar is the most severe. The condition can also affect development of the head and face. The most severely affected people have one central eye (cyclopia) and a tubular nasal structure (proboscis) located above the eye. Lobar holoprosencephaly is detectable at >18 weeks gestation, but the other three types can be detected at the 11-13 weeks scan. The prognosis of Alobar and semilobar are usually lethal within the first year of life. And for lobar fetus, life expectancy may be normal but usually with severe developmental delay and visual impairment.