Who Should Have a Fetal Heart Scan

Published on 07/06/2015 by admin

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2 Who Should Have a Fetal Heart Scan

Lisa K. Hornberger

I. GENERAL INFORMATION AND BACKGROUND

A. Level I or second trimester obstetric ultrasound

1. General fetal anatomical ultrasound exam is performed in the majority of low-risk pregnancies at 18 to 22 weeks of gestation to screen for congenital anomalies.

2. Personnel responsible include obstetricians, radiologists, and sonographers.

B. Level II or specialized fetal anatomical ultrasound

1. Specialized ultrasound is performed when an anomaly is suspected on the basis of history or biochemical abnormalities or when the results of either the limited or standard scan suggest the presence of fetal pathology.

2. Specialized ultrasound is performed by obstetricians, perinatologists, radiologists, and sonographers who have additional expertise in obstetric ultrasound.

C. Fetal echocardiography

1. Two-dimensional and Doppler echocardiographic evaluation includes detailed assessment of the cardiac anatomy, blood flow, heart rate and rhythm, and heart function.

2. Fetal echo is performed in pregnancies at risk for or with suspected structural, functional, or rhythm-related fetal heart disease.

3. Responsible personnel include:

a. Pediatric cardiologists with expertise in fetal and pediatric echocardiography.

    (1) They are knowledgeable about the nuances of congenital heart disease, including the medical and surgical outcomes.
    (2) They are knowledgeable about structural, functional, and rhythm-related fetal heart disease.

b. Obstetrics or radiology personnel with training in fetal echocardiography but with assistance from pediatric cardiologists for interpretation of the findings and prenatal counseling.

II. INDICATIONS

Indications for fetal echocardiography can be divided into three categories: maternal, fetal, and familial.

A Maternal indications

1. Maternal metabolic disorders.

a. Type 1 or 2 diabetes mellitus (preconception).

    (1) Reported incidence is twofold to fivefold higher than that of the general population.
    (2) Presence of fetal heart disease is not consistently linked to maternal hemoglobin A1c.
    (3) Major structural defects include such conditions as (but not limited to):
       (a) D-Transposition of the great arteries.
       (b) Hypoplastic left heart syndrome.
       (c) Tetralogy of Fallot.
       (d) Pulmonary atresia.
       (e) Tricuspid atresia.
    (4) Hypertrophic cardiomyopathy.
       (a) Hypertrophic cardiomyopathy typically does not evolve until late in gestation.
       (b) It is not itself an indication for fetal echocardiography because most affected infants are clinically well after birth and the pathology regresses spontaneously after birth.

b. Phenylketonuria.

    (1) Risk of defects is 14%, particularly with phenylalanine levels greater than 600 μmol/L up to 8 weeks’ gestation.
    (2) Specific lesions.
       (a) Left heart obstruction.
       (b) Tetralogy of Fallot.

2. Maternal congenital (or familial) heart disease.

a. Congenital heart disease: Risk depends upon the specific lesion (Table 2-1) but in general ranges from 5% to 13%.

b. Cardiomyopathy.

    (1) Risk depends upon the type of inheritance and age at presentation.
    (2) Most patients present in adolescence and are not identified prenatally.

3. Maternal autoimmune disease, specifically those associated with anti-Ro or anti-La autoantibodies (4%-25% risk in affected women).

a. Fetal atrioventricular heart block typically appears after 17 weeks’ gestation in a mother with autoantibodies and with or without clinical autoimmune disease.

b. Fetal cardiomyopathy with endocardial fibroelastosis.

4. Exposure to teratogens such as:

a. Alcohol: Atrial and ventricular septal defects.

b. Valproic acid.

    (1) Atrial and ventricular septal defects.
    (2) Aortic and pulmonary valve obstruction.
    (3) Coarctation of the aorta.

c. Vitamin A derivatives: Conotruncal abnormalities.

d. Lithium: Ebstein’s anomaly of the tricuspid valve.

TABLE 2-1

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B. Fetal indications

1. Obstetric ultrasound suggesting fetal heart disease.

a. Structural cardiac pathology is the indication that has been shown to provide the highest yield for true fetal structural cardiac pathology, which provides support for the critical importance of obstetric ultrasound screening.

b. Functional pathology.

    (1) Pregnancies at risk for fetal cardiovascular compromise.
       (a) Twin-twin transfusion syndrome (recipient twin).
       (b) Maternal infection associated with fetal myocarditis or cardiomyopathy (examples below).

         i. Coxsackievirus.
         ii. Cytomegalovirus.
         iii. Parvovirus.

       (c) High-output states.

         i. Fetal arteriovenous malformations (e.g., sacrococcygeal teratoma, vein of Galen aneurysm, placental chorioangioma).
         ii. Agenesis of the ductus venosus.
         iii. Fetal anemia.

    (2) Other risks.
       (a) Hydrops fetalis.
       (b) Polyhydramnios is a relative risk given that it can be associated with increased atrial pressures and atrial dilation.

c. Fetal dysrhythmia.

    (1) Ectopy.
    (2) Bradycardia.
    (3) Tachycardia.

2. Obstetric ultrasound suggesting fetal extracardiac disease.

a. Structural pathology involving other organ systems.

    (1) Renal dysgenesis.
    (2) Central nervous system pathology.
       (a) Dandy-Walker malformation.
       (b) Hydrocephalus.
       (c) Agenesis of the corpus callosum.
    (3) Omphalocele carries a 20% to 30% risk for both cardiac pathology and aneuploidy.
       (a) Ventricular and atrial septal defects.
       (b) Tetralogy of Fallot.
    (4) Diaphragmatic hernia: 15% to 25%.
    (5) Duodenal atresia.
    (6) Esophageal atresia or tracheoesophageal fistula.

b. Increased nuchal translucency in the first trimester, with a normal or abnormal karyotype.

    (1) Risk of aneuploidy.
    (2) Risk of fetal heart disease in the absence of aneuploidy is 3% to 6% overall.
    (3) The risk of aneuploidy and of heart disease without aneuploidy exponentially increases with increased nuchal thickness. The risk is up to 15% when thickness is greater than the 99th percentile for gestational age.

c. Findings suggesting chromosomal abnormality or aneuploidy or documented abnormal fetal karyotype.

    (1) Trisomy 21; however, 50% do not have structural heart disease, and many have structural heart disease that may be difficult to identify prenatally.
       (a) Ventricular and atrial septal defect.
       (b) Atrioventricular septal defect.
    (2) Trisomy 18.
       (a) Atrial and ventricular septal defects.
       (b) Dysplastic atrioventricular and semilunar valves.
       (c) Tetralogy of Fallot.
       (d) Double-outlet right ventricle with mitral atresia or stenosis.
    (3) Trisomy 13.
       (a) Atrial and ventricular septal defects.
       (b) Atrioventricular septal defect.
       (c) Tetralogy of Fallot.
    (4) Turner’s syndrome: Risk of left heart obstructive lesions.
       (a) Bicuspid aortic valve coarctation of the aorta.
       (b) Aortic valve stenosis.
       (c) Hypoplastic left heart syndrome.

C. Familial indications

1. Paternal congenital heart disease (see Table 2-1).

2. Mendelian syndromes.

a. Holt–Oram syndrome (autosomal dominant).

    (1) Atrial and ventricular septal defects.
    (2) The TBX5 gene is also associated with hypoplastic left heart syndrome.

b. DiGeorge’s syndrome (22q11.2 deletion, autosomal dominant): Conotruncal cardiovascular pathology (examples below).

    (1) Tetralogy of Fallot.
    (2) Truncus arteriosus.
    (3) Interrupted aortic arch type B.

c. Noonan’s syndrome (autosomal dominant).

    (1) Dysplastic pulmonary valve.
    (2) Pulmonary stenosis.
    (3) Hypertrophic cardiomyopathy.

d. Williams’ syndrome (autosomal dominant).

    (1) Supravalvular aortic stenosis.
    (2) Peripheral pulmonary artery stenosis.

e. Ellis–van Creveld syndrome (autosomal recessive).

    (1) Atrial and ventricular septal defects.
    (2) Atrioventricular septal defect.

f. Familial cardiomyopathy is the most common. Inheritance is autosomal dominant for both hypertrophic and dilated forms.

III. TAKE-HOME MESSAGE

A. Indications

1. Fetal echocardiography is indicated for pregnancies at risk for structural, functional, and rhythm-related fetal heart disease.

2. Indications for fetal echocardiography can be classified as maternal, fetal, and familial

3. The indication with the greatest positive yield is a finding of suspected fetal heart disease at routine fetal or obstetric ultrasound.

B. Diagnosis

Routine obstetric ultrasound screening is critical in the prenatal detection of fetal and congenital heart disease.

REFERENCES

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Ardinger RH. Genetic counseling in congenital heart disease. Pediatr Ann. 1997;26:99-104.

Boughman JA, Berg K, Astemborski JA, et al. Familial risks of congenital heart defect assessed in a population based epidemiologic study. Am J Med Gen. 1987;26:839-849.

Burn J, Brennan P, Little J, et al. Recurrence risks in offspring of adults with major heart defects: Results from first cohort of British collaborative study. Lancet. 1998;351:311-316.

Copel JA, Pilu G, Kleinman CS. Congenital heart disease and extracardiac anomalies: Associations and indications for fetal echocardiography. Am J Obstet Gynecol. 1986;154:1121-1124.

Digilio MC, Marino B, Giannotti A, et al. Recurrence risk figures for isolated tetralogy of Fallot after screening for 22q11 microdeletion. J Med Gen. 1997;34:188-190.

Gladman G, McCrindle BW, Boutin C, Smallhorn JF. Fetal echocardiographic screening of diabetic pregnancies for congenital heart disease. Am J Perinatol. 1997;14(2):59-62.

Gladman G, Silverman ED, Law YM, et al. Fetal echocardiographic screening of pregnancies of mothers with anti-Ro and/or anti-La antibodies. Am J Perinatol. 2002;19(2):73-80.

Hyett J, Perdu M, Sharland G, et al. Using fetal nuchal translucency to screen for major congenital cardiac defects at 10-14 weeks of gestation: Population based cohort study. BMJ. 1999;318:81-85.

McAuliffe FM, Hornberger LK, Winsor S, et al. Fetal cardiac defects and increased nuchal translucency thickness: A prospective study. Am J Obstet Gynecol. 2004;191(4):1486-1490.

Nicolaides KH, Brizot ML, Snijders RJM. Fetal nuchal translucency thickness: Ultrasound screening for fetal trisomy in the first trimester of pregnancy. Br J Obstet Gynaecol. 1994;101:782-786.

Nora JJ. From generational studies to a multilevel genetic–environmental interaction. J Am Coll Cardiol. 1994;23:1468-1471.

Nora JJ, Nora AH. Update on counseling the family with a first degree relative with a congenital heart defect. Am J Med Gen. 1988;29:137-142.

Rouse B, Azen C, Koch R, et al. Maternal Phenylketonuria Collaborative Study (MPKUCS) offspring: Facial anomalies, malformations, and early neurological sequelae. Am J Med Genet. 1997;69(1):89-95.

Souka AP, Krampl E, Bakalis S, et al. Outcome of pregnancy in chromosomally normal fetuses with increased nuchal translucency in the first trimester. Ultrasound Obstet Gynecol. 2001;18:9-17.

Tennstedt C, Chaoui R, Korner H, Dietel M. Spectrum of congenital heart defects and extracardiac malformations associated with chromosomal abnormalities: results of a seven year necropsy study. Heart. 1999;82:34-39.

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