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Infants and children with genetic syndromes frequently have associated cardiovascular abnormalities. It is important to recognize the cardiovascular anomalies associated with these genetic syndromes, as they account for significant morbidity and mortality. In this chapter, important genetic syndromes that are associated with cardiovascular manifestations are presented successively and include:

  • Down syndrome.

  • Turner syndrome.

  • DiGeorge syndrome.

  • Williams syndrome.

  • Marfan syndrome.

The focus of this chapter is on the cardiovascular abnormalities. For further clinical information on these genetic syndromes, please refer to Chapters 216, DiGeorge Syndrome; 221, Down Syndrome; 222 Turner Syndrome; and 223, Marfan Syndrome.

Down Syndrome

Patient story

A 35-week premature infant of a 42-year-old mother is delivered due to premature labor. A prior fetal echocardiogram showed an atrio-ventricular (AV) canal defect. The patient’s mother had denied amniocentesis and chromosomal testing during pregnancy. Post-natal examination of the infant reveals simian creases, macroglossia and sandal gap toe. The diagnosis of Down syndrome is made clinically and the diagnosis of AV canal defect is confirmed on echocardiogram (Figure 47-1). Surgery to repair the AV canal defect was scheduled at 3 to 6 months of age.


Apical four chamber view of a complete atrio-ventricular canal defect in an infant on echocardiogram. Note the atrial and ventricular septal defects (red and blue arrows respectively). The common atrioventricular valve (green arrows) sits in a horizontal plane along the atrioventricular groove which is characteristic of this defect. (Used with permission from Peter Aziz, MD.)


Down syndrome (Trisomy 21) is associated with a significant risk of congenital heart disease. Every infant with Down syndrome must be evaluated for the presence of congenital heart disease.


Trisomy 21


  • Cardiovascular malformations are found in 40 to 50 percent of individuals with Down syndrome.1

Etiology and Pathophysiology

  • A spectrum of endocardial cushion defects is common in Down syndrome and its prevalence is higher in patients with Down syndrome compared to that of general population.

  • The most common cardiac anomalies associated with Down syndrome include common AV canal, ventricular septal defect (VSD), tetralogy of Fallot and patent ductus arteriosus.

Risk factors

  • Advanced maternal age.


  • The diagnosis of Down syndrome is frequently made antenatally with first trimester screening lab tests and ultrasound appearance of increased nuchal cord thickness.

  • Diagnosis is often confirmed by chromosomal analysis from amniocentesis.

  • Antenatal diagnosis of cardiac defects in Down syndrome fetuses is accomplished by fetal echocardiography in the second trimester.

  • Newborn infants with AV canal defects are typically asymptomatic. They typically ...

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